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Wu Y, Shi J, Kippin TE, Plaxco KW. Codeposition Enhances the Performance of Electrochemical Aptamer-Based Sensors. Langmuir 2024; 40:8703-8710. [PMID: 38616608 DOI: 10.1021/acs.langmuir.4c00585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Electrochemical aptamer-based (EAB) sensors, a minimally invasive means of performing high-frequency, real-time measurement of drugs and biomarkers in situ in the body, have traditionally been fabricated by depositing their target-recognizing aptamer onto an interrogating gold electrode using a "sequential" two-step method involving deposition of the thiol-modified oligonucleotide (typically for 1 h) followed by incubation in mercaptohexanol solution (typically overnight) to complete the formation of a stable, self-assembled monolayer. Here we use EAB sensors targeting vancomycin, tryptophan, and phenylalanine to show that "codeposition", a less commonly employed EAB fabrication method in which the thiol-modified aptamer and the mercaptohexanol diluent are deposited on the electrode simultaneously and for as little as 1 h, improves the signal gain (relative change in signal upon the addition of high concentrations of the target) of the vancomycin and tryptophan sensors without significantly reducing their stability. In contrast, the gain of the phenylalanine sensor is effectively identical irrespective of the fabrication approach employed. This sensor, however, appears to employ binding-induced displacement of the redox reporter rather than binding-induced folding as its signal transduction mechanism, suggesting in turn a mechanism for the improvement observed for the other two sensors. Codeposition thus not only provides a more convenient means of fabricating EAB sensors but also can improve their performance.
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Affiliation(s)
- Yuyang Wu
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Jinyuan Shi
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, United States
- Neuroscience Research Institute, University of California, Santa Barbara, California 93106, United States
- Biological Engineering Graduate Program, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Biological Engineering Graduate Program, University of California Santa Barbara, Santa Barbara, California 93106, United States
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2
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Leung KK, Gerson J, Emmons N, Heemstra JM, Kippin TE, Plaxco KW. The Use of Xenonucleic Acids Significantly Reduces theIn Vivo Drift of Electrochemical Aptamer-Based Sensors. Angew Chem Int Ed Engl 2024:e202316678. [PMID: 38500260 DOI: 10.1002/anie.202316678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/09/2024] [Accepted: 03/17/2024] [Indexed: 03/20/2024]
Abstract
Electrochemical aptamer-based sensors support the high-frequency, real-time monitoring of molecules-of-interest in vivo. Achieving this requires methods for correcting the sensor drift seen during in vivo placements. While this correction ensures EAB sensor measurements remain accurate, as drift progresses it reduces the signal-to-noise ratio and precision. Here, we show that enzymatic cleavage of the sensor's target-recognizing DNA aptamer is a major source of this signal loss. To demonstrate this, we deployed a tobramycin-detecting EAB sensor analog fabricated with the DNase-resistant "xenonucleic acid" 2'O-methyl-RNA in a live rat. In contrast to the sensor employing the equivalent DNA aptamer, the 2'O-methyl-RNA aptamer sensor lost very little signal and had improved signal-to-noise. We further characterized the EAB sensor drift using unstructured DNA or 2'O-methyl-RNA oligonucleotides. While the two devices drift similarly in vitro in whole blood, the in vivo drift of the 2'O-methyl-RNA-employing device is less compared to the DNA-employing device. Studies of the electron transfer kinetics suggested that the greater drift of the latter sensor arises due to enzymatic DNA degradation. These findings, coupled with advances in the selection of aptamers employing XNA, suggest a means of improving EAB sensor stability when they are used to perform molecular monitoring in the living body.
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Affiliation(s)
- Kaylyn K Leung
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Nicole Emmons
- Department of Psychological and Brain Sciences, University of California, Santa Barbara
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Jennifer M Heemstra
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara
- Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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3
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Alkhamis O, Canoura J, Wu Y, Emmons NA, Wang Y, Honeywell KM, Plaxco KW, Kippin TE, Xiao Y. High-Affinity Aptamers for In Vitro and In Vivo Cocaine Sensing. J Am Chem Soc 2024; 146:3230-3240. [PMID: 38277259 DOI: 10.1021/jacs.3c11350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
The ability to quantify cocaine in biological fluids is crucial for both the diagnosis of intoxication and overdose in the clinic as well as investigation of the drug's pharmacological and toxicological effects in the laboratory. To this end, we have performed high-stringency in vitro selection to generate DNA aptamers that bind cocaine with nanomolar affinity and clinically relevant specificity, thus representing a dramatic improvement over the current-generation, micromolar-affinity, low-specificity cocaine aptamers. Using these novel aptamers, we then developed two sensors for cocaine detection. The first, an in vitro fluorescent sensor, successfully detects cocaine at clinically relevant levels in 50% human serum without responding significantly to other drugs of abuse, endogenous substances, or a diverse range of therapeutic agents. The second, an electrochemical aptamer-based sensor, supports the real-time, seconds-resolved measurement of cocaine concentrations in vivo in the circulation of live animals. We believe the aptamers and sensors developed here could prove valuable for both point-of-care and on-site clinical cocaine detection as well as fundamental studies of cocaine neuropharmacology.
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Affiliation(s)
- Obtin Alkhamis
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607, United States
| | - Juan Canoura
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607, United States
| | - Yuyang Wu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Nicole A Emmons
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106, United States
| | - Yuting Wang
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106, United States
| | - Kevin M Honeywell
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106, United States
| | - Yi Xiao
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607, United States
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4
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Li S, Dai J, Zhu M, Arroyo-Currás N, Li H, Wang Y, Wang Q, Lou X, Kippin TE, Wang S, Plaxco KW, Li H, Xia F. Implantable Hydrogel-Protective DNA Aptamer-Based Sensor Supports Accurate, Continuous Electrochemical Analysis of Drugs at Multiple Sites in Living Rats. ACS Nano 2023; 17:18525-18538. [PMID: 37703911 DOI: 10.1021/acsnano.3c06520] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The ability to track the levels of specific molecules, such as drugs, metabolites, and biomarkers, in the living body, in real time and for long durations, would improve our understanding of health and our ability to diagnose, treat, and monitor disease. To this end, we are developing electrochemical aptamer-based (EAB) biosensors, a general platform supporting high-frequency, real-time molecular measurements in the living body. Here we report that the use of an agarose hydrogel protective layer for EAB sensors significantly improves their signaling stability when deployed in the complex, highly time-varying environments found in vivo. The improved stability is sufficient that these hydrogel-protected sensors achieved good baseline stability and precision when deployed in situ in the veins, muscles, bladder, or tumors of living rats without the use of the drift correction approaches traditionally required in such placements. Finally, our implantable gel-protective EAB sensors achieved good biocompatibility when deployed in vivo in the living rats without causing any severe inflammation.
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Affiliation(s)
- Shaoguang Li
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Jun Dai
- Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Man Zhu
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Netzahualcóyotl Arroyo-Currás
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Hongxing Li
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Yuanyuan Wang
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Quan Wang
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Xiaoding Lou
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Tod E Kippin
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106, United States
- The Neuroscience Research Institute, University of California, Santa Barbara, California 93106, United States
| | - Shixuan Wang
- Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Kevin W Plaxco
- Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, United States
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California, Santa Barbara, California 93106, United States
- Interdepartmental Program in Biomolecular Science and Engineering, University of California, Santa Barbara, California 93106, United States
| | - Hui Li
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
| | - Fan Xia
- State Key Laboratory of Biogeology Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, People's Republic of China
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5
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McDonough MH, Stocker SL, Kippin T, Meiring W, Plaxco KW. Using seconds-resolved pharmacokinetic datasets to assess pharmacokinetic models encompassing time-varying physiology. Br J Clin Pharmacol 2023; 89:2798-2812. [PMID: 37186478 PMCID: PMC10799768 DOI: 10.1111/bcp.15756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 04/04/2023] [Accepted: 04/10/2023] [Indexed: 05/17/2023] Open
Abstract
AIM Pharmacokinetics have historically been assessed using drug concentration data obtained via blood draws and bench-top analysis. The cumbersome nature of these typically constrains studies to at most a dozen concentration measurements per dosing event. This, in turn, limits our statistical power in the detection of hours-scale, time-varying physiological processes. Given the recent advent of in vivo electrochemical aptamer-based (EAB) sensors, however, we can now obtain hundreds of concentration measurements per administration. Our aim in this paper was to assess the ability of these time-dense datasets to describe time-varying pharmacokinetic models with good statistical significance. METHODS We used seconds-resolved measurements of plasma tobramycin concentrations in rats to statistically compare traditional one- and two-compartmental pharmacokinetic models to new models in which the proportional relationship between a drug's plasma concentration and its elimination rate varies in response to changing kidney function. RESULTS We found that a modified one-compartment model in which the proportionality between the plasma concentration of tobramycin and its elimination rate falls reciprocally with time either meets or is preferred over the standard two-compartment pharmacokinetic model for half of the datasets characterized. When we reduced the impact of the drug's rapid distribution phase on the model, this one-compartment, time-varying model was statistically preferred over the standard one-compartment model for 80% of our datasets. CONCLUSIONS Our results highlight both the impact that simple physiological changes (such as varying kidney function) can have on drug pharmacokinetics and the ability of high-time resolution EAB sensor measurements to identify such impacts.
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Affiliation(s)
- Matthew H. McDonough
- Department of Statistics and Applied Probability, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Sophie L. Stocker
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Camperdown NSW 2006, Sydney, Australia
- St Vincent’s Clinical School, University of New South Wales, Sydney, Australia
| | - Tod Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- The Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Wendy Meiring
- Department of Statistics and Applied Probability, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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6
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Roehrich B, Leung KK, Gerson J, Kippin TE, Plaxco KW, Sepunaru L. Calibration-Free, Seconds-Resolved In Vivo Molecular Measurements using Fourier-Transform Impedance Spectroscopy Interrogation of Electrochemical Aptamer Sensors. ACS Sens 2023; 8:3051-3059. [PMID: 37584531 PMCID: PMC10463274 DOI: 10.1021/acssensors.3c00632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 08/02/2023] [Indexed: 08/17/2023]
Abstract
Electrochemical aptamer-based (EAB) sensors are capable of measuring the concentrations of specific molecules in vivo, in real time, and with a few-second time resolution. For their signal transduction mechanism, these sensors utilize a binding-induced conformational change in their target-recognizing, redox-reporter-modified aptamer to alter the rate of electron transfer between the reporter and the supporting electrode. While a variety of voltammetric techniques have been used to monitor this change in kinetics, they suffer from various drawbacks, including time resolution limited to several seconds and sensor-to-sensor variation that requires calibration to remove. Here, however, we show that the use of fast Fourier transform electrochemical impedance spectroscopy (FFT-EIS) to interrogate EAB sensors leads to improved (here better than 2 s) time resolution and calibration-free operation, even when such sensors are deployed in vivo. To showcase these benefits, we demonstrate the approach's ability to perform real-time molecular measurements in the veins of living rats.
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Affiliation(s)
- Brian Roehrich
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kaylyn K. Leung
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
- Center
for Bioengineering, University of California
Santa Barbara, Santa Barbara, California 93106, United States
| | - Julian Gerson
- Department
of Psychological and Brain Sciences, University
of California, Santa Barbara, California 93106, United States
- Center
for Bioengineering, University of California
Santa Barbara, Santa Barbara, California 93106, United States
| | - Tod E. Kippin
- Department
of Psychological and Brain Sciences, University
of California, Santa Barbara, California 93106, United States
- Department
of Molecular Cellular and Developmental Biology, University of California, Santa
Barbara, California 93106,United States
| | - Kevin W. Plaxco
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
- Center
for Bioengineering, University of California
Santa Barbara, Santa Barbara, California 93106, United States
| | - Lior Sepunaru
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa Barbara, California 93106, United States
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7
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Son K, Uzawa T, Ito Y, Kippin T, Plaxco KW, Fujie T. Survey of oligoethylene glycol-based self-assembled monolayers on electrochemical aptamer-based sensor in biological fluids. Biochem Biophys Res Commun 2023; 668:1-7. [PMID: 37230045 DOI: 10.1016/j.bbrc.2023.05.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 04/26/2023] [Accepted: 05/10/2023] [Indexed: 05/27/2023]
Abstract
The ability to monitor levels of endogenous markers and clearance profiles of drugs and their metabolites can improve the quality of biomedical research and precision with which therapies are individualized. Towards this end, electrochemical aptamer-based (EAB) sensors have been developed that support the real-time monitoring of specific analytes in vivo with clinically relevant specificity and sensitivity. A challenge associated with the in vivo deployment of EAB sensors, however, is how to manage the signal drift which, although correctable, ultimately leads to unacceptably low signal-to-noise ratios, limiting the measurement duration. Motivated by the correction of signal drift, in this paper, we have explored the use of oligoethylene glycol (OEG), a widely employed antifouling coating, to reduce the signal drift in EAB sensors. Counter to expectations, however, when challenged in 37 °C whole blood in vitro, EAB sensors employing OEG-modified self-assembled monolayers exhibit both greater drift and reduced signal gain, compared with those employ a simple, hydroxyl-terminated monolayer. On the other hand, when EAB sensor was prepared with a mix monolayer using MCH and lipoamido OEG 2 alcohol, reduced signal noise was observed compared to the same sensor prepared with MCH presumably due to improved SAM construction. These results suggest broader exploration of antifouling materials will be required to improve the signal drift of EAB sensors.
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Affiliation(s)
- Kon Son
- School of Life Science and Technology, Tokyo Institute of Technology, B-50, Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan; RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Takanori Uzawa
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan; RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Yoshihiro Ito
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan; RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Tod Kippin
- Department of Psychological and Brain Sciences, UCSB, Santa Barbara, CA, 93106, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, UCSB, Santa Barbara, CA, 93106, USA
| | - Toshinori Fujie
- School of Life Science and Technology, Tokyo Institute of Technology, B-50, Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan; RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan; Living Systems Materialogy (LiSM) Research Group, International Research Frontiers Initiative (IRFI), Tokyo Institute of Technology, B-50, Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan.
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8
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Chung J, Plaxco KW, Sepunaru L. Precise Electrochemical Sizing of Individual Electro-Inactive Particles. J Vis Exp 2023. [PMID: 37590554 DOI: 10.3791/65116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023] Open
Abstract
Nanoimpact electrochemistry enables the time-resolved in situ characterization (e.g., size, catalytic activity) of single nanomaterial units, providing a means of elucidating heterogeneities that would be masked in ensemble studies. To implement this technique with redox inactive particles, a solution-phase redox reaction is used to produce a steady-state background current on a disk ultramicroelectrode. When a particle adsorbs onto the electrode, it produces a stepwise reduction in the exposed electrode area, which produces, in turn, a stepwise decrease in the current commensurate with the size of the adsorbing species. Historically, however, nanoimpact electrochemistry has suffered from "edge effects," in which the radial diffusion layer formed at the circumference of the ultramicroelectrodes renders the step size dependent not only on the size of the particle but also on where it lands on the electrode. The introduction of electrocatalytic current generation, however, mitigates the heterogeneity caused by edge effects, thus improving the measurement precision. In this approach, termed "electrocatalytic interruption," a substrate that regenerates the redox probe at the diffusion layer is introduced. This shifts the rate-limiting step of the current generation from diffusion to the homogeneous reaction rate constant, thus reducing flux heterogeneity and increasing the precision of particle sizing by an order of magnitude. The protocol described here explains the set-up and data collection employed in nanoimpact experiments implementing this effect for improved precision in the sizing of redox in-active materials.
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Affiliation(s)
- Julia Chung
- Interdepartmental Program in Biomedical Science and Engineering, University of California at Santa Barbara
| | - Kevin W Plaxco
- Interdepartmental Program in Biomedical Science and Engineering, University of California at Santa Barbara; Department of Chemistry and Biochemistry, University of California at Santa Barbara
| | - Lior Sepunaru
- Department of Chemistry and Biochemistry, University of California at Santa Barbara;
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9
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Friedel M, Werbovetz B, Drexelius A, Watkins Z, Bali A, Plaxco KW, Heikenfeld J. Continuous molecular monitoring of human dermal interstitial fluid with microneedle-enabled electrochemical aptamer sensors. Lab Chip 2023. [PMID: 37395135 DOI: 10.1039/d3lc00210a] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The ability to continually collect diagnostic information from the body during daily activity has revolutionized the monitoring of health and disease. Much of this monitoring, however, has been of physical "vital signs", with the monitoring of molecular markers having been limited to glucose, primarily due to the lack of other medically relevant molecules for which continuous measurements are possible in bodily fluids. Electrochemical aptamer sensors, however, have a recent history of successful in vivo demonstrations in rat animal models. Herein, we present the first report of real-time human molecular data collected using such sensors, successfully demonstrating their ability to measure the concentration of phenylalanine in dermal interstitial fluid after an oral bolus. To achieve this, we used a device that employs three hollow microneedles to couple the interstitial fluid to an ex vivo, phenylalanine-detecting sensor. The resulting architecture achieves good precision over the physiological concentration range and clinically relevant, 20 min lag times. By also demonstrating 90 days dry room-temperature shelf storage, the reported work also reaches another important milestone in moving such sensors to the clinic. While the devices demonstrated are not without remaining challenges, the results at minimum provide a simple method by which aptamer sensors can be quickly moved into human subjects for testing.
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Affiliation(s)
- Mark Friedel
- Novel Devices Laboratory, College of Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA.
| | - Benjamin Werbovetz
- Novel Devices Laboratory, College of Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA.
| | - Amy Drexelius
- Novel Devices Laboratory, College of Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA.
| | - Zach Watkins
- Novel Devices Laboratory, College of Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA.
| | - Ahilya Bali
- Novel Devices Laboratory, College of Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA.
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | - Jason Heikenfeld
- Novel Devices Laboratory, College of Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA.
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10
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Gerson J, Erdal MK, McDonough MH, Ploense KL, Dauphin-Ducharme P, Honeywell KM, Leung KK, Arroyo-Curras N, Gibson JM, Emmons NA, Meiring W, Hespanha JP, Plaxco KW, Kippin TE. High-precision monitoring of and feedback control over drug concentrations in the brains of freely moving rats. Sci Adv 2023; 9:eadg3254. [PMID: 37196087 PMCID: PMC10191434 DOI: 10.1126/sciadv.adg3254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/12/2023] [Indexed: 05/19/2023]
Abstract
Knowledge of drug concentrations in the brains of behaving subjects remains constrained on a number of dimensions, including poor temporal resolution and lack of real-time data. Here, however, we demonstrate the ability of electrochemical aptamer-based sensors to support seconds-resolved, real-time measurements of drug concentrations in the brains of freely moving rats. Specifically, using such sensors, we achieve <4 μM limits of detection and 10-s resolution in the measurement of procaine in the brains of freely moving rats, permitting the determination of the pharmacokinetics and concentration-behavior relations of the drug with high precision for individual subjects. In parallel, we have used closed-loop feedback-controlled drug delivery to hold intracranial procaine levels constant (±10%) for >1.5 hours. These results demonstrate the utility of such sensors in (i) the determination of the site-specific, seconds-resolved neuropharmacokinetics, (ii) enabling the study of individual subject neuropharmacokinetics and concentration-response relations, and (iii) performing high-precision control over intracranial drug levels.
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Affiliation(s)
- Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
- Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106, USA
| | - Murat Kaan Erdal
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - Matthew H. McDonough
- Department of Statistics and Applied Probability, University of California, Santa Barbara, CA 93106, USA
| | - Kyle L. Ploense
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | | | - Kevin M. Honeywell
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
| | - Kaylyn K. Leung
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | - Netzahualcoyotl Arroyo-Curras
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jenny M. Gibson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
| | - Nicole A. Emmons
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
| | - Wendy Meiring
- Department of Statistics and Applied Probability, University of California, Santa Barbara, CA 93106, USA
| | - Joao P. Hespanha
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - Kevin W. Plaxco
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106, USA
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | - Tod E. Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA
- Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
- Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
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11
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Leung KK, Gerson J, Emmons N, Roehrich B, Verrinder E, Fetter LC, Kippin TE, Plaxco KW. A tight squeeze: geometric effects on the performance of three-electrode electrochemical-aptamer based sensors in constrained, in vivo placements. Analyst 2023; 148:1562-1569. [PMID: 36891771 DOI: 10.1039/d2an02096c] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Electrochemical, aptamer-based (EAB) sensors are the first molecular monitoring technology that is (1) based on receptor binding and not the reactivity of the target, rendering it fairly general, and (2) able to support high-frequency, real-time measurements in situ in the living body. To date, EAB-derived in vivo measurements have largely been performed using three electrodes (working, reference, counter) bundled together within a catheter for insertion into the rat jugular. Exploring this architecture, here we show that the placement of these electrodes inside or outside of the lumen of the catheter significantly impacts sensor performance. Specifically, we find that retaining the counter electrode within the catheter increases the resistance between it and the working electrode, increasing the capacitive background. In contrast, extending the counter electrode outside the lumen of the catheter reduces this effect, significantly enhancing the signal-to-noise of intravenous molecular measurements. Exploring counter electrode geometries further, we find that they need not be larger than the working electrode. Putting these observations together, we have developed a new intravenous EAB architecture that achieves improved performance while remaining short enough to safely emplace in the rat jugular. These findings, though explored here with EAB sensors may prove important for the design of many electrochemical biosensors.
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Affiliation(s)
- Kaylyn K Leung
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Nicole Emmons
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Brian Roehrich
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Elsi Verrinder
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Lisa C Fetter
- Biomolecular Sciences and Engineering, University of California, Santa Barbara, California 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA 93106, USA.,Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Biomolecular Sciences and Engineering, University of California, Santa Barbara, California 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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12
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Parolo C, Idili A, Heikenfeld J, Plaxco KW. Conformational-switch biosensors as novel tools to support continuous, real-time molecular monitoring in lab-on-a-chip devices. Lab Chip 2023; 23:1339-1348. [PMID: 36655710 PMCID: PMC10799767 DOI: 10.1039/d2lc00716a] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Recent years have seen continued expansion of the functionality of lab on a chip (LOC) devices. Indeed LOCs now provide scientists and developers with useful and versatile platforms across a myriad of chemical and biological applications. The field still fails, however, to integrate an often important element of bench-top analytics: real-time molecular measurements that can be used to "guide" a chemical response. Here we describe the analytical techniques that could provide LOCs with such real-time molecular monitoring capabilities. It appears to us that, among the approaches that are general (i.e., that are independent of the reactive or optical properties of their targets), sensing strategies relying on binding-induced conformational change of bioreceptors are most likely to succeed in such applications.
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Affiliation(s)
- Claudio Parolo
- Barcelona Institute for Global Health, Hospital Clínic Universitat de Barcelona, 08036, Barcelona, Spain
| | - Andrea Idili
- Department of Chemical Science and Technologies, University of Rome, Tor Vergata, 00133 Rome, Italy
| | - Jason Heikenfeld
- Novel Devices Laboratory, University of Cincinnati, Cincinnati, Ohio, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA.
- Interdepartmental Program in Biomolecular Science and Engineering, University of California Santa Barbara, Santa Barbara, California, USA
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13
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Flatebo C, Conkright WR, Beckner ME, Batchelor RH, Kippin TE, Heikenfeld J, Plaxco KW. Efforts toward the continuous monitoring of molecular markers of performance. J Sci Med Sport 2023:S1440-2440(23)00028-2. [PMID: 36841706 DOI: 10.1016/j.jsams.2023.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 01/04/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023]
Abstract
OBJECTIVES Technologies supporting the continuous, real-time measurement of blood oxygen saturation and plasma glucose levels have improved our ability to monitor performance status. Our ability to monitor other molecular markers of performance, however, including the hormones known to indicate overtraining and general health, has lagged. That is, although a number of other molecular markers of performance status have been identified, we have struggled to develop viable technologies supporting their real-time monitoring in the body. Here we review biosensor approaches that may support such measurements, as well as the molecules potentially of greatest interest to monitor. DESIGN Narrative literature review. METHOD Literature review. RESULTS Significant effort has been made to harness the specificity, affinity, and generalizability of biomolecular recognition in a platform technology supporting continuous in vivo molecular measurements. Most biosensor approaches, however, are either not generalizable to most targets, or fail when challenged in the complex environments found in vivo. Electrochemical aptamer-based sensors, in contrast, are the first technology to simultaneously achieve both of these critical attributes. In an effort to illustrate the potential of this platform technology, we both critically review the literature describing it and briefly survey some of the molecular performance markers we believe will prove advantageous to monitor using it. CONCLUSIONS Electrochemical aptamer-based sensors may be the first truly generalizable technology for monitoring specific molecules in situ in the body and how adaptation of the platform to subcutaneous microneedles will enable the real-time monitoring of performance markers via a wearable, minimally invasive device.
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Affiliation(s)
- Charlotte Flatebo
- Institute for Collaborative Biotechnologies, University of California Santa Barbara, USA
| | | | | | | | - Tod E Kippin
- Neuroscience Research Institute, Department of Psychological and Brain Sciences, University of California Santa Barbara, USA
| | - Jason Heikenfeld
- Biomedical, Electrical, and Chemical Engineering, Director Novel Devices Laboratory, University of Cincinnati, USA
| | - Kevin W Plaxco
- Institute for Collaborative Biotechnologies, University of California Santa Barbara, USA; Department of Chemistry and Biochemistry, Biological Engineering Graduate Program, University of California Santa Barbara, USA.
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14
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Ortega G, Chamorro-Garcia A, Ricci F, Plaxco KW. On the Rational Design of Cooperative Receptors. Annu Rev Biophys 2023; 52:319-337. [PMID: 36737603 DOI: 10.1146/annurev-biophys-091222-082247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cooperativity (homotropic allostery) is the primary mechanism by which evolution steepens the binding curves of biomolecular receptors to produce more responsive input-output behavior in biomolecular systems. Motivated by the ubiquity with which nature employs this effect, over the past 15 years we, together with other groups, have engineered this mechanism into several otherwise noncooperative receptors. These efforts largely aimed to improve the utility of such receptors in artificial biotechnologies, such as synthetic biology and biosensors, but they have also provided the first quantitative, experimental tests of longstanding ideas about the mechanisms underlying cooperativity. In this article, we review the literature on the design of this effect, paying particular attention to the design strategies involved, the extent to which each can be rationally applied to (and optimized for) new receptors, and what each teaches us about the origins and optimization of this important phenomenon. Expected final online publication date for the Annual Review of Biophysics, Volume 52 is May 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Gabriel Ortega
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Derio, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Alejandro Chamorro-Garcia
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA; .,Biological Engineering Graduate Program, University of California, Santa Barbara, California, USA.,Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Rome, Italy
| | - Francesco Ricci
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Rome, Italy
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA; .,Biological Engineering Graduate Program, University of California, Santa Barbara, California, USA
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15
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Chamorro-Garcia A, Gerson J, Flatebo C, Fetter L, Downs AM, Emmons N, Ennis HL, Milosavić N, Yang K, Stojanovic M, Ricci F, Kippin TE, Plaxco KW. Real-Time, Seconds-Resolved Measurements of Plasma Methotrexate In Situ in the Living Body. ACS Sens 2023; 8:150-157. [PMID: 36534756 DOI: 10.1021/acssensors.2c01894] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Dose-limiting toxicity and significant patient-to-patient pharmacokinetic variability often render it difficult to achieve the safe and effective dosing of drugs. This is further compounded by the slow, cumbersome nature of the analytical methods used to monitor patient-specific pharmacokinetics, which inevitably rely on blood draws followed by post-facto laboratory analysis. Motivated by the pressing need for improved "therapeutic drug monitoring", we are developing electrochemical aptamer-based (EAB) sensors, a minimally invasive biosensor architecture that can provide real-time, seconds-resolved measurements of drug levels in situ in the living body. A key advantage of EAB sensors is that they are generalizable to the detection of a wide range of therapeutic agents because they are independent of the chemical or enzymatic reactivity of their targets. Three of the four therapeutic drug classes that have, to date, been shown measurable using in vivo EAB sensors, however, bind to nucleic acids as part of their mode of action, leaving open questions regarding the extent to which the approach can be generalized to therapeutics that do not. Here, we demonstrate real-time, in vivo measurements of plasma methotrexate, an antimetabolite (a mode of action not reliant on DNA binding) chemotherapeutic, following human-relevant dosing in a live rat animal model. By providing hundreds of drug concentration values, the resulting seconds-resolved measurements succeed in defining key pharmacokinetic parameters, including the drug's elimination rate, peak plasma concentration, and exposure (area under the curve), with unprecedented 5 to 10% precision. With this level of precision, we easily identify significant (>2-fold) differences in drug exposure occurring between even healthy rats given the same mass-adjusted methotrexate dose. By providing a real-time, seconds-resolved window into methotrexate pharmacokinetics, such measurements can be used to precisely "individualize" the dosing of this significantly toxic yet vitally important chemotherapeutic.
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Affiliation(s)
- Alejandro Chamorro-Garcia
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Dipartimento di Scienze e Tecnologie Chimiche, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Charlotte Flatebo
- Institute for Collaborative Biotechnologies, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Lisa Fetter
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Alex M Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Nicole Emmons
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Herbert L Ennis
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States
| | - Nenad Milosavić
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States
| | - Kyungae Yang
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States
| | - Milan Stojanovic
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University New York, New York, New York 10032, United States.,Department of Biomedical Engineering and Systems Biology, Columbia University New York, New York, New York 10032, United States
| | - Francesco Ricci
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Tod E Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Biological Engineering Graduate Program, University of California Santa Barbara, Santa Barbara, California 93106, United States
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16
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Wu Y, Ranallo S, Del Grosso E, Chamoro-Garcia A, Ennis HL, Milosavić N, Yang K, Kippin T, Ricci F, Stojanovic M, Plaxco KW. Using Spectroscopy to Guide the Adaptation of Aptamers into Electrochemical Aptamer-Based Sensors. Bioconjug Chem 2023; 34:124-132. [PMID: 36044602 PMCID: PMC10799766 DOI: 10.1021/acs.bioconjchem.2c00275] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Electrochemical aptamer-based (EAB) sensors utilize the binding-induced conformational change of an electrode-attached, redox-reporter-modified aptamer to transduce target recognition into an easily measurable electrochemical output. Because this signal transduction mechanism is single-step and rapidly reversible, EAB sensors support high-frequency, real-time molecular measurements, and because it recapitulates the reagentless, conformation-linked signaling seen in vivo among naturally occurring receptors, EAB sensors are selective enough to work in the complex, time-varying environments found in the living body. The fabrication of EAB sensors, however, requires that their target-recognizing aptamer be modified such that (1) it undergoes the necessary binding-induced conformational change and (2) that the thermodynamics of this "conformational switch" are tuned to ensure that they reflect an acceptable trade-off between affinity and signal gain. That is, even if an "as-selected" aptamer achieves useful affinity and specificity, it may fail when adapted to the EAB platform because it lacks the binding-induced conformational change required to support EAB signaling. In this paper we reveal the spectroscopy-guided approaches we use to modify aptamers such that they support the necessary binding-induced conformational change. Specifically, using newly reported aptamers, we demonstrate the systematic design of EAB sensors achieving clinically and physiologically relevant specificity, limits of detection, and dynamic range against the targets methotrexate and tryptophan.
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Affiliation(s)
- Yuyang Wu
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Simona Ranallo
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Chemistry Department, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Erica Del Grosso
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Chemistry Department, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Alejandro Chamoro-Garcia
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Chemistry Department, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Herbert L Ennis
- Department of Medicine, Columbia University, New York, New York 10032, United States
| | - Nenad Milosavić
- Department of Medicine, Columbia University, New York, New York 10032, United States
| | - Kyungae Yang
- Department of Medicine, Columbia University, New York, New York 10032, United States
| | - Tod Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department of Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Francesco Ricci
- Chemistry Department, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
| | - Milan Stojanovic
- Department of Medicine, Columbia University, New York, New York 10032, United States
- Department of Biomedical Engineering and Systems Biology, Columbia University, New York, New York 10032, United States
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Biological Engineering Graduate Program, University of California Santa Barbara, Santa Barbara, California 93106, United States
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17
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Bidinger SL, Keene ST, Han S, Plaxco KW, Malliaras GG, Hasan T. Pulsed transistor operation enables miniaturization of electrochemical aptamer-based sensors. Sci Adv 2022; 8:eadd4111. [PMID: 36383656 PMCID: PMC9668304 DOI: 10.1126/sciadv.add4111] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/28/2022] [Indexed: 06/16/2023]
Abstract
By simultaneously transducing and amplifying, transistors offer advantages over simpler, electrode-based transducers in electrochemical biosensors. However, transistor-based biosensors typically use static (i.e., DC) operation modes that are poorly suited for sensor architectures relying on the modulation of charge transfer kinetics to signal analyte binding. Thus motivated, here, we translate the AC "pulsed potential" approach typically used with electrochemical aptamer-based (EAB) sensors to an organic electrochemical transistor (OECT). Specifically, by applying a linearly sweeping square-wave potential to an aptamer-functionalized gate electrode, we produce current modulation across the transistor channel two orders of magnitude larger than seen for the equivalent, electrode-based biosensor. Unlike traditional EAB sensors, our aptamer-based OECT (AB-OECT) sensors critically maintain output current even with miniaturization. The pulsed transistor operation demonstrated here could be applied generally to sensors relying on kinetics-based signaling, expanding opportunities for noninvasive and high spatial resolution biosensing.
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Affiliation(s)
- Sophia L. Bidinger
- Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Ave., Cambridge CB3 0FA, UK
| | - Scott T. Keene
- Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Ave., Cambridge CB3 0FA, UK
- Department of Physics, University of Cambridge, Cambridge CB3 0FA, UK
| | - Sanggil Han
- Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Ave., Cambridge CB3 0FA, UK
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry and Biological Engineering Program, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - George G. Malliaras
- Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Ave., Cambridge CB3 0FA, UK
| | - Tawfique Hasan
- Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Ave., Cambridge CB3 0FA, UK
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18
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Abstract
The continuous, real-time measurement of specific molecules in situ in the body would greatly improve our ability to understand, diagnose, and treat disease. The vast majority of continuous molecular sensing technologies, however, either (1) rely on the chemical or enzymatic reactivity of their targets, sharply limiting their scope, or (2) have never been shown (and likely will never be shown) to operate in the complex environments found in vivo. Against this background, here we review electrochemical aptamer-based (EAB) sensors, an electrochemical approach to real-time molecular monitoring that has now seen 15 years of academic development. The strengths of the EAB platform are significant: to date it is the only molecular measurement technology that (1) functions independently of the chemical reactivity of its targets, and is thus general, and (2) supports in vivo measurements. Specifically, using EAB sensors we, and others, have already reported the real-time, seconds-resolved measurements of multiple, unrelated drugs and metabolites in situ in the veins and tissues of live animals. Against these strengths, we detail the platform's remaining weaknesses, which include still limited measurement duration (hours, rather than the more desirable days) and the difficulty in obtaining sufficiently high performance aptamers against new targets, before then detailing promising approaches overcoming these hurdles. Finally, we close by exploring the opportunities we believe this potentially revolutionary technology (as well as a few, possibly competing, technologies) will create for both researchers and clinicians.
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Affiliation(s)
- Alex M. Downs
- Sandia National Laboratories, Albuquerque, NM 87106, USA
| | - Kevin W. Plaxco
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA,Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA,Corresponding author:
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19
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Chamorro-Garcia A, Parolo C, Ortega G, Idili A, Green J, Ricci F, Plaxco KW. The sequestration mechanism as a generalizable approach to improve the sensitivity of biosensors and bioassays. Chem Sci 2022; 13:12219-12228. [PMID: 36349092 PMCID: PMC9601244 DOI: 10.1039/d2sc03901j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 09/16/2022] [Indexed: 07/25/2023] Open
Abstract
Biosensors and bioassays, both of which employ proteins and nucleic acids to detect specific molecular targets, have seen significant applications in both biomedical research and clinical practice. This success is largely due to the extraordinary versatility, affinity, and specificity of biomolecular recognition. Nevertheless, these receptors suffer from an inherent limitation: single, saturable binding sites exhibit a hyperbolic relationship (the "Langmuir isotherm") between target concentration and receptor occupancy, which in turn limits the sensitivity of these technologies to small variations in target concentration. To overcome this and generate more responsive biosensors and bioassays, here we have used the sequestration mechanism to improve the steepness of the input/output curves of several bioanalytical methods. As our test bed for this we employed sensors and assays against neutrophil gelatinase-associated lipocalin (NGAL), a kidney biomarker for which enhanced sensitivity will improve the monitoring of kidney injury. Specifically, by introducing sequestration we have improved the responsiveness of an electrochemical aptamer based (EAB) biosensor, and two bioassays, a paper-based "dipstick" assay and an enzyme-linked immunosorbent assay (ELISA). Doing so we have narrowed the dynamic range of these sensors and assays several-fold, thus enhancing their ability to measure small changes in target concentration. Given that introducing sequestration requires only the addition of the appropriate concentration of a high-affinity "depletant," the mechanism appears simple and easily adaptable to tuning the binding properties of the receptors employed in a wide range of biosensors and bioassays.
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Affiliation(s)
- Alejandro Chamorro-Garcia
- Department of Chemistry and Biochemistry University of California Santa Barbara (UCSB) Santa Barbara CA 93106 USA
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica 00133 Rome Italy
| | - Claudio Parolo
- ISGlobal-Barcelona Institute for Global Health Carrer del Rosselló 132 08036 Barcelona Spain
| | - Gabriel Ortega
- Ikerbasque, Basque Foundation for Science 48013 Bilbao Spain
- Precision Medicine and Metabolism Laboratory, CIC BioGUNE, Basque Research and Technology Alliance, Parque Tecnológico de Bizkaia 48160 Derio Spain
| | - Andrea Idili
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica 00133 Rome Italy
| | - Joshua Green
- Department of Chemistry and Biochemistry University of California Santa Barbara (UCSB) Santa Barbara CA 93106 USA
| | - Francesco Ricci
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica 00133 Rome Italy
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry University of California Santa Barbara (UCSB) Santa Barbara CA 93106 USA
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20
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Plaxco KW. Molecular vital signs: wearable technologies for the real-time measurement of molecular markers of health and human performance. J Sci Med Sport 2022. [DOI: 10.1016/j.jsams.2021.11.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Batchelor RH, Plaxco KW. Electrochemical aptamer-based sensors: a platform technology supporting seconds-resolved, real-time molecular monitoring in the living body. J Sci Med Sport 2022. [DOI: 10.1016/j.jsams.2021.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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Downs AM, Gerson J, Leung KK, Honeywell KM, Kippin T, Plaxco KW. Improved calibration of electrochemical aptamer-based sensors. Sci Rep 2022; 12:5535. [PMID: 35365672 PMCID: PMC8976050 DOI: 10.1038/s41598-022-09070-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 02/24/2022] [Indexed: 12/22/2022] Open
Abstract
Electrochemical aptamer-based (EAB) sensors support the real-time, high frequency measurement of pharmaceuticals and metabolites in-situ in the living body, rendering them a potentially powerful technology for both research and clinical applications. Here we explore quantification using EAB sensors, examining the impact of media selection and temperature on measurement performance. Using freshly-collected, undiluted whole blood at body temperature as both our calibration and measurement conditions, we demonstrate accuracy of better than ± 10% for the measurement of our test bed drug, vancomycin. Comparing titrations collected at room and body temperature, we find that matching the temperature of calibration curve collection to the temperature used during measurements improves quantification by reducing differences in sensor gain and binding curve midpoint. We likewise find that, because blood age impacts the sensor response, calibrating in freshly collected blood can improve quantification. Finally, we demonstrate the use of non-blood proxy media to achieve calibration without the need to collect fresh whole blood.
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Affiliation(s)
- Alex M Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kaylyn K Leung
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kevin M Honeywell
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Tod Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,The Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kevin W Plaxco
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA. .,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA. .,Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.
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23
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Ranallo S, Sorrentino D, Delibato E, Ercolani G, Plaxco KW, Ricci F. Back Cover: Protein–Protein Communication Mediated by an Antibody‐Responsive DNA Nanodevice (Angew. Chem. Int. Ed. 12/2022). Angew Chem Int Ed Engl 2022. [DOI: 10.1002/anie.202201863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Simona Ranallo
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Daniela Sorrentino
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Elisabetta Delibato
- Department of Food Safety, Nutrition and Veterinary Public Health Istituto Superiore di Sanità Viale Regina Elena 299 Rome Italy
| | - Gianfranco Ercolani
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Francesco Ricci
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
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24
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Ranallo S, Sorrentino D, Delibato E, Ercolani G, Plaxco KW, Ricci F. Protein–Protein Communication Mediated by an Antibody‐Responsive DNA Nanodevice**. Angew Chem Int Ed Engl 2022; 61:e202115680. [DOI: 10.1002/anie.202115680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Indexed: 11/09/2022]
Affiliation(s)
- Simona Ranallo
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Daniela Sorrentino
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Elisabetta Delibato
- Department of Food Safety, Nutrition and Veterinary Public Health Istituto Superiore di Sanità Viale Regina Elena 299 Rome Italy
| | - Gianfranco Ercolani
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Francesco Ricci
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
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25
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Abstract
Electrochemical aptamer-based (EAB) sensors encompass the only biosensor approach yet reported that is simultaneously: (1) independent of the chemical or enzymatic reactivity of its target, rendering it general; (2) continuous and real-time; and (3) selective enough to deploy in situ in the living body. Consistent with this, in vivo EAB sensors supporting the seconds-resolved, real-time measurement of multiple drugs and metabolites have been reported, suggesting the approach may prove of value in biomedical research and the diagnosis, treatment, and monitoring of disease. However, to apply these devices in long-duration animal models, much less in human patients, requires that they be free of any significant pathogen load. Thus motivated, here we have characterized the compatibility of EAB sensors with standard sterilization and high-level disinfection techniques. Doing so, we find that, while many lead to significant sensor degradation, treatment with CIDEX OPA (0.55% ortho-phthalaldehyde) leads to effective disinfection without causing any detectable loss in sensor performance.
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Affiliation(s)
- Julia Chung
- Interdepartmental Program in Biomedical Science and Engineering, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Lior Sepunaru
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Kevin W. Plaxco
- Interdepartmental Program in Biomedical Science and Engineering, University of California at Santa Barbara, Santa Barbara, California 93106, USA
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, USA
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26
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Ranallo S, Sorrentino D, Delibato E, Ercolani G, Plaxco KW, Ricci F. Rücktitelbild: Protein–Protein Communication Mediated by an Antibody‐Responsive DNA Nanodevice (Angew. Chem. 12/2022). Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202201863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Simona Ranallo
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Daniela Sorrentino
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Elisabetta Delibato
- Department of Food Safety, Nutrition and Veterinary Public Health Istituto Superiore di Sanità Viale Regina Elena 299 Rome Italy
| | - Gianfranco Ercolani
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Francesco Ricci
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
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27
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Ranallo S, Sorrentino D, Delibato E, Ercolani G, Plaxco KW, Ricci F. Protein–Protein Communication Mediated by an Antibody‐Responsive DNA Nanodevice**. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Simona Ranallo
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Daniela Sorrentino
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Elisabetta Delibato
- Department of Food Safety, Nutrition and Veterinary Public Health Istituto Superiore di Sanità Viale Regina Elena 299 Rome Italy
| | - Gianfranco Ercolani
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry University of California, Santa Barbara Santa Barbara CA 93106 USA
| | - Francesco Ricci
- Department of Chemistry University of Rome Tor Vergata Via della Ricerca Scientifica 00133 Rome Italy
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28
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Idili A, Montón H, Medina-Sánchez M, Ibarlucea B, Cuniberti G, Schmidt OG, Plaxco KW, Parolo C. Continuous monitoring of molecular biomarkers in microfluidic devices. Prog Mol Biol Transl Sci 2022; 187:295-333. [PMID: 35094779 DOI: 10.1016/bs.pmbts.2021.07.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The ability to monitor molecular targets is crucial in fields ranging from healthcare to industrial processing to environmental protection. Devices employing biomolecules to achieve this goal are called biosensors. Over the last half century researchers have developed dozens of different biosensor approaches. In this chapter we analyze recent advances in the biosensing field aiming at adapting these to the problem of continuous molecular monitoring in complex sample streams, and how the merging of these sensors with lab-on-a-chip technologies would be beneficial to both. To do so we discuss (1) the components that comprise a biosensor, (2) the challenges associated with continuous molecular monitoring in complex sample streams, (3) how different sensing strategies deal with (or fail to deal with) these challenges, and (4) the implementation of these technologies into lab-on-a-chip architectures.
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Affiliation(s)
- Andrea Idili
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, United States; Department of Chemical Science and Technologies, University of Rome, Tor Vergata, Rome, Italy
| | - Helena Montón
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, United States
| | | | - Bergoi Ibarlucea
- Institute for Materials Science and Max Bergmann Center for Biomaterials, Technische Universität Dresden, Dresden, Germany; Center for Advancing Electronics Dresden (CFAED), Technische Universität Dresden, Dresden, Germany
| | - Gianaurelio Cuniberti
- Institute for Materials Science and Max Bergmann Center for Biomaterials, Technische Universität Dresden, Dresden, Germany; Center for Advancing Electronics Dresden (CFAED), Technische Universität Dresden, Dresden, Germany
| | - Oliver G Schmidt
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Dresden, Germany; Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz, Germany; School of Science, TU Dresden, Dresden, Germany
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, United States; Interdepartmental Program in Biomolecular Science and Engineering University of California, Santa Barbara, CA, United States
| | - Claudio Parolo
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, United States; Barcelona Institute for Global Health (ISGlobal) Hospital Clínic, Barcelona, Spain.
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29
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Dauphin-Ducharme P, Ploense KL, Arroyo-Currás N, Kippin TE, Plaxco KW. Electrochemical Aptamer-Based Sensors: A Platform Approach to High-Frequency Molecular Monitoring In Situ in the Living Body. Methods Mol Biol 2022; 2393:479-492. [PMID: 34837195 DOI: 10.1007/978-1-0716-1803-5_25] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The monitoring of specific molecules in the living body has historically required sample removal (e.g., blood draws, microdialysis) followed by analysis via cumbersome, laboratory-bound processes. Those few exceptions to this rule (e.g., glucose, pyruvate, the monoamines) are monitored using "one-off" technologies reliant on the specific enzymatic or redox reactivity of their targets, and thus not generalizable to the measurement of other targets. In response we have developed in vivo electrochemical aptamer-based (E-AB) sensors, a modular, receptor-based measurement technology that is independent of the chemical reactivity of its targets, and thus has the potential to be generalizable to a wide range of analytes. To further the adoption of this in vivo molecular measurement approach by other researchers and to accelerate its ultimate translation to the clinic, we present here our standard protocols for the fabrication and use of intravenous E-AB sensors.
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Affiliation(s)
| | - Kyle L Ploense
- Center for Bioengineering, UC Santa Barbara, Santa Barbara, CA, USA
| | | | - Tod E Kippin
- Department of Psychological and Brain Sciences, UC Santa Barbara, Santa Barbara, CA, USA.,Department of Molecular Developmental and Cellular Biology, UC Santa Barbara, Santa Barbara, CA, USA.,Neuroscience Research Institute, UC Santa Barbara, Santa Barbara, CA, USA
| | - Kevin W Plaxco
- Center for Bioengineering, UC Santa Barbara, Santa Barbara, CA, USA. .,Department of Chemistry and Biochemistry, UC Santa Barbara, Santa Barbara, CA, USA.
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30
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Chung J, Hertler P, Plaxco KW, Sepunaru L. Catalytic Interruption Mitigates Edge Effects in the Characterization of Heterogeneous, Insulating Nanoparticles. J Am Chem Soc 2021; 143:18888-18898. [PMID: 34735140 DOI: 10.1021/jacs.1c04971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Blocking electrochemistry, a subfield of nanochemistry, enables nondestructive, in situ measurement of the concentration, size, and size heterogeneity of highly dilute, nanometer-scale materials. This approach, in which the adsorptive impact of individual particles on a microelectrode prevents charge exchange with a freely diffusing electroactive redox mediator, has expanded the scope of electrochemistry to the study of redox-inert materials. A limitation, however, remains: inhomogeneous current fluxes associated with enhanced mass transfer occurring at the edges of planar microelectrodes confound the relationship between the size of the impacting particle and the signal it generates. These "edge effects" lead to the overestimation of size heterogeneity and, thus, poor sample characterization. In response, we demonstrate here the ability of catalytic current amplification (EC') to reduce this problem, an effect we term "electrocatalytic interruption". Specifically, we show that the increase in mass transport produced by a coupled chemical reaction significantly mitigates edge effects, returning estimated particle size distributions much closer to those observed using ex situ electron microscopy. In parallel, electrocatalytic interruption enhances the signal observed from individual particles, enabling the detection of particles significantly smaller than is possible via conventional blocking electrochemistry. Finite element simulations indicate that the rapid chemical kinetics created by this approach contributes to the amplification of the electronic signal to restore analytical precision and reliably detect and characterize the heterogeneity of nanoscale electro-inactive materials.
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Affiliation(s)
- Julia Chung
- Interdepartmental Program in Biomolecular Science and Engineering, University of California at Santa Barbara, Santa Barbara, California 93106, United States
| | - Phoebe Hertler
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W Plaxco
- Interdepartmental Program in Biomolecular Science and Engineering, University of California at Santa Barbara, Santa Barbara, California 93106, United States.,Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, United States
| | - Lior Sepunaru
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, United States
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31
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Kang D, Yu J, Xia F, Huang J, Zeng H, Tirrell M, Israelachvili J, Plaxco KW. Nanometer-Scale Force Profiles of Short Single- and Double-Stranded DNA Molecules on a Gold Surface Measured Using a Surface Forces Apparatus. Langmuir 2021; 37:13346-13352. [PMID: 34730362 PMCID: PMC8968159 DOI: 10.1021/acs.langmuir.1c01966] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Using a surface forces apparatus (SFA), we have studied the nanomechanical behavior of short single-stranded and partially and fully double-stranded DNA molecules attached via one end to a self-assembled monolayer on a gold surface. Our results confirm the previously proposed "mushroom-like" polymer structure for surface-attached, single-stranded DNA at low packing density and a "brush-like" structure for the same construct at higher density. At low density we observe a transition to "rigid rod" behavior upon addition of DNA complementary to the surface-attached single strand as the fraction of molecules that are double-stranded increases, with a concomitant increase in the SFA-observed thickness of the monolayer and the characteristic length of the observed repulsive forces. At higher densities, in contrast, this transition is effectively eliminated, presumably because the single-stranded state is already extended in its "brush" state. Taken together, these studies offer insights into the structure and physics of surface-attached short DNAs, providing new guidance for the rational design of DNA-modified functional surfaces.
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Affiliation(s)
- Di Kang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Jing Yu
- School of Materials Science and Engineering, Nanyang Technological University, 639798 Singapore
| | - Fan Xia
- Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Jun Huang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada
| | - Matthew Tirrell
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
- Center for Molecular Engineering, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Jacob Israelachvili
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Interdepartmental Program in Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
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32
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Chamorro-Garcia A, Ortega G, Mariottini D, Green J, Ricci F, Plaxco KW. Switching the aptamer attachment geometry can dramatically alter the signalling and performance of electrochemical aptamer-based sensors. Chem Commun (Camb) 2021; 57:11693-11696. [PMID: 34673866 DOI: 10.1039/d1cc04557a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrochemical aptamer-based (EAB) sensors, composed of an electrode-bound DNA aptamer with a redox reporter on the distal end, offer the promise of high-frequency, real-time molecular measurements in complex sample matrices and even in vivo. Here we assess the extent to which switching the aptamer terminus that is electrode-bound and the one that is redox-reporter-modified affects the performance of these sensors. Using sensors against doxorubicin, cocaine, and vancomycin as our test beds, we find that both signal gain (the relative signal change seen in the presence of a saturating target) and the frequency dependence of gain depend strongly on the attachment orientation, suggesting that this easily investigated variable is a worthwhile parameter to optimize in the design of new EAB sensors.
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Affiliation(s)
- Alejandro Chamorro-Garcia
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica, Rome 00133, Italy
| | - Gabriel Ortega
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Basque Research and Technology Alliance, Parque Tecnológico de Bizkaia, Derio, Spain.,Department of Chemistry and Biochemistry, University of California Santa Barbara (UCSB), Santa Barbara, CA 93106, USA
| | - Davide Mariottini
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica, Rome 00133, Italy
| | - Joshua Green
- Department of Chemistry and Biochemistry, University of California Santa Barbara (UCSB), Santa Barbara, CA 93106, USA
| | - Francesco Ricci
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica, Rome 00133, Italy
| | - Kevin W Plaxco
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA. .,Department of Chemistry and Biochemistry, University of California Santa Barbara (UCSB), Santa Barbara, CA 93106, USA
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33
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Ortega G, Aguilar MA, Gautam BK, Plaxco KW. The effect of charged residue substitutions on the thermodynamics of protein-surface interactions. Protein Sci 2021; 30:2408-2417. [PMID: 34719069 DOI: 10.1002/pro.4215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 01/07/2023]
Abstract
The interactions of proteins with surfaces are important in both biological processes and biotechnologies. In contrast to decades of study regarding the biophysics of proteins in bulk solution, however, our mechanistic understanding of the biophysics of proteins interacting with surfaces remains largely qualitative. In response, we have set to explore quantitatively the thermodynamics of protein-surface interactions. In this work, we explore systematically the role of electrostatics in modulating the interaction between proteins and charged surfaces. In particular, we use electrochemistry to explore the extent to which a macroscopic, hydroxyl-coated surface held at a slightly negative potential affects the folding thermodynamics of surface-attached protein variants with different composition of charged amino acids. Doing so, we find that attachment to the surface generally leads to a net stabilization, presumably due to excluded volume effects that reduce the entropy of the unfolded state. The magnitude of this stabilization, however, is strongly correlated with the charged-residue content of the protein. In particular, we find statistically significant correlations with both the net charge of the protein, with greater negative charge leading to less stabilization by the surface, and with the number of arginines, with more arginines leading to greater stabilization. Such findings refine our understanding of protein-surface interactions, providing in turn a guiding rationale to achieve the functional deposition of proteins on artificial surfaces for implementation in, for example, protein-based biotechnologies.
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Affiliation(s)
- Gabriel Ortega
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California, USA.,Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Basque Research and Technology Alliance, Parque Tecnológico de Bizkaia, Derio, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Bizkaia, Spain
| | - Miguel A Aguilar
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA
| | - Bishal K Gautam
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California, USA
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34
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Leung KK, Downs AM, Ortega G, Kurnik M, Plaxco KW. Elucidating the Mechanisms Underlying the Signal Drift of Electrochemical Aptamer-Based Sensors in Whole Blood. ACS Sens 2021; 6:3340-3347. [PMID: 34491055 DOI: 10.1021/acssensors.1c01183] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The ability to monitor drugs, metabolites, hormones, and other biomarkers in situ in the body would greatly advance both clinical practice and biomedical research. To this end, we are developing electrochemical aptamer-based (EAB) sensors, a platform technology able to perform real-time, in vivo monitoring of specific molecules irrespective of their chemical or enzymatic reactivity. An important obstacle to the deployment of EAB sensors in the challenging environments found in the living body is signal drift, whereby the sensor signal decreases over time. To date, we have demonstrated a number of approaches by which this drift can be corrected sufficiently well to achieve good measurement precision over multihour in vivo deployments. To achieve a much longer in vivo measurement duration, however, will likely require that we understand and address the sources of this effect. In response, here, we have systematically examined the mechanisms underlying the drift seen when EAB sensors and simpler, EAB-like devices are challenged in vitro at 37 °C in whole blood as a proxy for in vivo conditions. Our results demonstrate that electrochemically driven desorption of a self-assembled monolayer and fouling by blood components are the two primary sources of signal loss under these conditions, suggesting targeted approaches to remediating this degradation and thus improving the stability of EAB sensors and other, similar electrochemical biosensor technologies when deployed in the body.
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Affiliation(s)
- Kaylyn K. Leung
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Alex M. Downs
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Gabriel Ortega
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Martin Kurnik
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
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35
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Downs AM, Gerson J, Hossain MN, Ploense K, Pham M, Kraatz HB, Kippin T, Plaxco KW. Nanoporous Gold for the Miniaturization of In Vivo Electrochemical Aptamer-Based Sensors. ACS Sens 2021; 6:2299-2306. [PMID: 34038076 DOI: 10.1021/acssensors.1c00354] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Electrochemical aptamer-based sensors enable real-time molecular measurements in the living body. The spatial resolution of these measurements and ability to perform measurements in targeted locations, however, is limited by the length and width of the device's working electrode. Historically, achieving good signal to noise in the complex, noisy in vivo environment has required working electrode lengths of 3-6 mm. To enable sensor miniaturization, here we have enhanced the signaling current obtained for a sensor of given macroscopic dimensions by increasing its surface area. Specifically, we produced nanoporous gold via an electrochemical alloying/dealloying technique to increase the microscopic surface area of our working electrodes by up to 100-fold. Using this approach, we have miniaturized in vivo electrochemical aptamer-based (EAB) sensors (here using sensors against the antibiotic, vancomycin) by a factor of 6 while retaining sensor signal and response times. Conveniently, the fabrication of nanoporous gold is simple, parallelizable, and compatible with both two- and three-dimensional electrode architectures, suggesting that it may be of value to a range of electrochemical biosensor applications.
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Affiliation(s)
- Alex M. Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - M. Nur Hossain
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Kyle Ploense
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Michael Pham
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Heinz-Bernhard Kraatz
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Tod Kippin
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
- The Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W. Plaxco
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
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36
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Abstract
Current health emergencies have highlighted the need to have rapid, sensitive, and convenient platforms for the detection of specific antibodies. In response, we report here the design of an electrochemical DNA circuit that responds quantitatively to multiple specific antibodies. The approach employs synthetic antigen-conjugated nucleic acid strands that are rationally designed to induce a strand displacement reaction and release a redox reporter-modified strand upon the recognition of a specific target antibody. The approach is sensitive (low nanomolar detection limit), specific (no signal is observed in the presence of non-targeted antibodies), and selective (the platform can be employed in complex media, including 90% serum). The programmable nature of the strand displacement circuit makes it also versatile, and we demonstrate here the detection of five different antibodies, including three of which are clinically relevant. Using different redox reporters, we also show that the antibody-responsive circuit can be multiplexed and responds to different antibodies in the same solution without crosstalk.
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Affiliation(s)
- Sara Bracaglia
- Department of Chemical Science and Technologies, University of Rome, Tor Vergata, 00133 Rome, Italy
| | - Simona Ranallo
- Department of Chemical Science and Technologies, University of Rome, Tor Vergata, 00133 Rome, Italy
- Department of Chemistry and Biochemistry, University of California Santa Barbara, CA93106 Santa Barbara, California, United States
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, CA93106 Santa Barbara, California, United States
| | - Francesco Ricci
- Department of Chemical Science and Technologies, University of Rome, Tor Vergata, 00133 Rome, Italy
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37
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Affiliation(s)
- Kevin J Cash
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO, USA.,Quantitative Biosciences and Engineering Program, Colorado School of Mines, Golden, CO, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA. .,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California, USA.
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38
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Li S, Lin L, Chang X, Si Z, Plaxco KW, Khine M, Li H, Xia F. A wrinkled structure of gold film greatly improves the signaling of electrochemical aptamer-based biosensors. RSC Adv 2021; 11:671-677. [PMID: 35423693 PMCID: PMC8693351 DOI: 10.1039/d0ra09174j] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 11/27/2020] [Indexed: 01/01/2023] Open
Abstract
Electrochemical aptamer-based (E-AB) sensors provide a great opportunity towards the goal of point-of-care and wearable sensing technologies due to their good sensitivity and selectivity. Nevertheless, the output signals from this sensor class remain low when sensors are interrogated via square-wave voltammetry. This low signaling limits the sensor's precision for its capability to detect small changes in target concentrations. To circumvent this, we proposed here the use of a readily shrink-induced, wrinkled Au-coating polyolefin film to immobilize a greater number of DNA probes and thus improve the signaling. Specifically, wrinkled gold film exhibits a 5.5-fold increase of surface area in comparison to the unwrinkled ones. Using these substrates we fabricated a set of E-AB sensors of three biological molecules, including kanamycin, doxorubicin and ATP. We achieved up to 10-fold increase in its current and also good accuracies within ±20% error in the target concentration range across 2 orders of magnitude. A wrinkled gold substrate greatly improves the signaling of electrochemical aptamer-based biosensors, achieving up to 10-fold increase in signals.![]()
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Affiliation(s)
- Shaoguang Li
- Engineering Research Center of Nano-Geomaterials of Ministry of Education
- Faculty of Materials Science and Chemistry
- China University of Geosciences
- Wuhan 430074
- China
| | - Lancy Lin
- Department of Biomedical Engineering
- University of California, Irvine
- Irvine
- USA
| | - Xueman Chang
- Engineering Research Center of Nano-Geomaterials of Ministry of Education
- Faculty of Materials Science and Chemistry
- China University of Geosciences
- Wuhan 430074
- China
| | - Zhixiao Si
- Engineering Research Center of Nano-Geomaterials of Ministry of Education
- Faculty of Materials Science and Chemistry
- China University of Geosciences
- Wuhan 430074
- China
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry
- University of California Santa Barbara
- Santa Barbara
- USA
- Center for Bioengineering
| | - Michelle Khine
- Department of Biomedical Engineering
- University of California, Irvine
- Irvine
- USA
| | - Hui Li
- Engineering Research Center of Nano-Geomaterials of Ministry of Education
- Faculty of Materials Science and Chemistry
- China University of Geosciences
- Wuhan 430074
- China
| | - Fan Xia
- Engineering Research Center of Nano-Geomaterials of Ministry of Education
- Faculty of Materials Science and Chemistry
- China University of Geosciences
- Wuhan 430074
- China
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39
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Downs AM, Gerson J, Ploense KL, Plaxco KW, Dauphin-Ducharme P. Subsecond-Resolved Molecular Measurements Using Electrochemical Phase Interrogation of Aptamer-Based Sensors. Anal Chem 2020; 92:14063-14068. [PMID: 32959647 DOI: 10.1021/acs.analchem.0c03109] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent years have seen the development of a number of biosensor architectures that rely on target binding-induced changes in the rate of electron transfer from an electrode-bound receptor. Most often, the interrogation of these sensors has relied on voltammetric methods, such as square-wave voltammetry, which limit their time resolution to a few seconds. Here, we describe the use of an impedance-based approach, which we have termed electrochemical phase interrogation, as a means of collecting high time resolution measurements with sensors in this class. Specifically, using changes in the electrochemical phase to monitor target binding in an electrochemical-aptamer based (EAB) sensor, we achieve subsecond temporal resolution and multihour stability in measurements performed directly in undiluted whole blood. Electrochemical phase interrogation also offers improved insights into EAB sensors' signaling mechanism. By modeling the interfacial resistance and capacitance using equivalent circuits, we find that the only parameter that is altered by target binding is the charge-transfer resistance. This confirms previous claims that binding-induced changes in electron-transfer kinetics drive signaling in this class of sensors. Considering that a wide range of electrochemical biosensor architectures rely on this signaling mechanism, we believe that electrochemical phase interrogation may prove generalizable toward subsecond measurements of molecular targets.
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Affiliation(s)
- Alex M Downs
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Julian Gerson
- Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kyle L Ploense
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado 80309, United States
| | - Kevin W Plaxco
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States.,Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
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40
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Ortega G, Kurnik M, Gautam BK, Plaxco KW. Attachment of Proteins to a Hydroxyl-Terminated Surface Eliminates the Stabilizing Effects of Polyols. J Am Chem Soc 2020; 142:15349-15354. [PMID: 32786756 DOI: 10.1021/jacs.0c05719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The physics of proteins interacting with surfaces can differ significantly from those seen when the same proteins are free in bulk solution. As an example, we describe here the extent to which site-specific attachment to a chemically well-defined macroscopic surface alters the ability of several stabilizing and destabilizing cosolutes to modulate protein folding thermodynamics. We determined this via guanidinium denaturations performed in the presence of varying concentrations of cosolutes when proteins were either site-specifically attached to self-assembled monolayers on gold or free in bulk solution. Doing this we found that the extent to which guanidinium (a destabilizing Hofmeister cation), sulfate (a stabilizing Hofmeister anion), and urea (a neutral denaturant) alter the folding free energy remains indistinguishable whether proteins are surface-attached or free in bulk solution. In sharp contrast, however, neutral osmolytes sucrose and glycerol, which significantly stabilize proteins in bulk solution, do not measurably affect their stability when they are attached to a hydroxyl-terminated surface. In contrast, we recovered bulk solution-like stabilization when the attachment surface was instead carboxyl-terminated. It thus appears that chemistry-specific surface interactions can dramatically alter the way in which biomolecules interact with other components of the system.
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Affiliation(s)
- Gabriel Ortega
- Department of Chemistry and Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106, United States.,Center for Bioengineering, University of California-Santa Barbara, Santa Barbara, California 93106, United States
| | - Martin Kurnik
- Department of Chemistry and Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106, United States.,Center for Bioengineering, University of California-Santa Barbara, Santa Barbara, California 93106, United States
| | - Bishal K Gautam
- Department of Chemistry and Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106, United States.,Center for Bioengineering, University of California-Santa Barbara, Santa Barbara, California 93106, United States
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41
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Kurnik M, Pang EZ, Plaxco KW. An Electrochemical Biosensor Architecture Based on Protein Folding Supports Direct Real‐Time Measurements in Whole Blood. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Martin Kurnik
- Department of Chemistry and Biochemistry University of California Santa Barbara Santa Barbara CA 93106 USA
- Center for Bioengineering University of California Santa Barbara Santa Barbara CA 93106 USA
| | - Eric Z. Pang
- Department of Chemistry and Biochemistry University of California Santa Barbara Santa Barbara CA 93106 USA
- Center for Bioengineering University of California Santa Barbara Santa Barbara CA 93106 USA
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry University of California Santa Barbara Santa Barbara CA 93106 USA
- Center for Bioengineering University of California Santa Barbara Santa Barbara CA 93106 USA
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42
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Kurnik M, Pang EZ, Plaxco KW. An Electrochemical Biosensor Architecture Based on Protein Folding Supports Direct Real-Time Measurements in Whole Blood. Angew Chem Int Ed Engl 2020; 59:18442-18445. [PMID: 32668060 DOI: 10.1002/anie.202007256] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/10/2020] [Indexed: 12/21/2022]
Abstract
The ability to monitor drug and biomarker concentrations in the body with high frequency and in real time would revolutionize our understanding of biology and our capacity to personalize medicine. The few in vivo molecular sensors that currently exist, however, all rely on the specific chemical or enzymatic reactivity of their targets and thus are not generalizable. In response, we demonstrate here an electrochemical sensing architecture based on binding-induced protein folding that is 1) independent of the reactivity of its targets, 2) reagentless, real-time, and with a resolution of seconds, and 3) selective enough to deploy in undiluted bodily fluids. As a proof of principle, we use the SH3 domain from human Fyn kinase to build a sensor that discriminates between the protein's peptide targets and responds rapidly and quantitatively even when challenged in whole blood. The resulting sensor architecture could drastically expand the chemical space accessible to continuous, real-time biosensors.
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Affiliation(s)
- Martin Kurnik
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Eric Z Pang
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.,Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
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43
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Bissonnette S, Del Grosso E, Simon AJ, Plaxco KW, Ricci F, Vallée-Bélisle A. Optimizing the Specificity Window of Biomolecular Receptors Using Structure-Switching and Allostery. ACS Sens 2020; 5:1937-1942. [PMID: 32297508 DOI: 10.1021/acssensors.0c00237] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To ensure maximum specificity (i.e., minimize cross-reactivity with structurally similar analogues of the desired target), most bioassays invoke "stringency", the careful tuning of the conditions employed (e.g., pH, ionic strength, or temperature). Willingness to control assay conditions will fall, however, as quantitative, single-step biosensors begin to replace multistep analytical processes. This is especially true for sensors deployed in vivo, where the tuning of such parameters is not just inconvenient but impossible. In response, we describe here the rational adaptation of two strategies employed by nature to tune the affinity of biomolecular receptors so as to optimize the placement of their specificity "windows" without the need to alter measurement conditions: structure-switching and allosteric control. We quantitatively validate these approaches using two distinct, DNA-based receptors: a simple, linear-chain DNA suitable for detecting a complementary DNA strand and a structurally complex DNA aptamer used for the detection of a small-molecule drug. Using these models, we show that, without altering assay conditions, structure-switching and allostery can tune the concentration range over which a receptor achieves optimal specificity over orders of magnitude, thus optimally matching the specificity window with the range of target concentrations expected to be seen in a given application.
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Affiliation(s)
- Stéphanie Bissonnette
- Laboratory of Biosensors & Nanomachines, Département de Chimie, Département de Biochimie et Médecine Moléculaire, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Erica Del Grosso
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
- Consorzio Interuniversitario Biostrutture e Biosistemi “INBB”, Rome 00136, Italy
| | | | | | - Francesco Ricci
- Dipartimento di Scienze e Tecnologie Chimiche, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
- Consorzio Interuniversitario Biostrutture e Biosistemi “INBB”, Rome 00136, Italy
| | - Alexis Vallée-Bélisle
- Laboratory of Biosensors & Nanomachines, Département de Chimie, Département de Biochimie et Médecine Moléculaire, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada
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44
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Abstract
The ability to monitor protein biomarkers continuously and in real-time would significantly advance the precision of medicine. Current protein-detection techniques, however, including ELISA and lateral flow assays, provide only time-delayed, single-time-point measurements, limiting their ability to guide prompt responses to rapidly evolving, life-threatening conditions. In response, here we present an electrochemical aptamer-based sensor (EAB) that supports high-frequency, real-time biomarker measurements. Specifically, we have developed an electrochemical, aptamer-based (EAB) sensor against Neutrophil Gelatinase-Associated Lipocalin (NGAL), a protein that, if present in urine at levels above a threshold value, is indicative of acute renal/kidney injury (AKI). When deployed inside a urinary catheter, the resulting reagentless, wash-free sensor supports real-time, high-frequency monitoring of clinically relevant NGAL concentrations over the course of hours. By providing an "early warning system", the ability to measure levels of diagnostically relevant proteins such as NGAL in real-time could fundamentally change how we detect, monitor, and treat many important diseases.
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Affiliation(s)
- Claudio Parolo
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Andrea Idili
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Gabriel Ortega
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Andrew Csordas
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Alex Hsu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Netzahualcóyotl Arroyo-Currás
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
| | - Qin Yang
- Aptitude Medical Systems, Inc., Santa Barbara, California 93105, United States
| | | | - Jinpeng Wang
- Aptitude Medical Systems, Inc., Santa Barbara, California 93105, United States
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Interdepartmental Program in Biomolecular Science and Engineering University of California, Santa Barbara, Santa Barbara, California 93106, United States
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45
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Arroyo-Currás N, Sadeia M, Ng AK, Fyodorova Y, Williams N, Afif T, Huang CM, Ogden N, Andresen Eguiluz RC, Su HJ, Castro CE, Plaxco KW, Lukeman PS. An electrochemical biosensor exploiting binding-induced changes in electron transfer of electrode-attached DNA origami to detect hundred nanometer-scale targets. Nanoscale 2020; 12:13907-13911. [PMID: 32578652 DOI: 10.1039/d0nr00952k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The specific detection in clinical samples of analytes with dimensions in the tens to hundreds of nanometers, such as viruses and large proteins, would improve disease diagnosis. Detection of these "mesoscale" analytes (as opposed to their nanoscale components), however, is challenging as it requires the simultaneous binding of multiple recognition sites often spaced over tens of nanometers. In response, we have adapted DNA origami, with its unparalleled customizability to precisely display multiple target-binding sites over the relevant length scale, to an electrochemical biosensor platform. Our proof-of-concept employs triangular origami covalently attached to a gold electrode and functionalized with redox reporters. Electrochemical interrogation of this platform successfully monitors mesoscale, target-binding-induced changes in electron transfer in a manner consistent with coarse-grained molecular dynamics simulations. Our approach enables the specific detection of analytes displaying recognition sites that are separated by ∼40 nm, a spacing significantly greater than that achieved in similar sensor architectures employing either antibodies or aptamers.
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Affiliation(s)
- Netzahualcóyotl Arroyo-Currás
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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46
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Ploense KL, Dauphin-Ducharme P, Arroyo-Curras N, Williams S, Schwarz N, Kippin T, Plaxco KW. Real‐time pharmacokinetic and pharmacodynamic measurements of drugs within the brains of freely behaving rats. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.07174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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47
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Clark PL, Plaxco KW, Sosnick TR. Water as a Good Solvent for Unfolded Proteins: Folding and Collapse are Fundamentally Different. J Mol Biol 2020; 432:2882-2889. [PMID: 32044346 DOI: 10.1016/j.jmb.2020.01.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/28/2020] [Accepted: 01/29/2020] [Indexed: 12/30/2022]
Abstract
The argument that the hydrophobic effect is the primary effect driving the folding of globular proteins is nearly universally accepted (including by the authors). But does this view also imply that water is a "poor" solvent for the unfolded states of these same proteins? Here we argue that the answer is "no," that is, folding to a well-packed, extensively hydrogen-bonded native structure differs fundamentally from the nonspecific chain collapse that defines a poor solvent. Thus, the observation that a protein folds in water does not necessitate that water is a poor solvent for its unfolded state. Indeed, chain-solvent interactions that are marginally more favorable than nonspecific intrachain interactions are beneficial to protein function because they destabilize deleterious misfolded conformations and inter-chain interactions.
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Affiliation(s)
- Patricia L Clark
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA.
| | - Kevin W Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA.
| | - Tobin R Sosnick
- Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA.
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48
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49
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Parolo C, Greenwood AS, Ogden NE, Kang D, Hawes C, Ortega G, Arroyo-Currás N, Plaxco KW. E-DNA scaffold sensors and the reagentless, single-step, measurement of HIV-diagnostic antibodies in human serum. Microsyst Nanoeng 2020; 6:13. [PMID: 34567628 PMCID: PMC8433188 DOI: 10.1038/s41378-019-0119-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 10/28/2019] [Accepted: 11/07/2019] [Indexed: 05/05/2023]
Abstract
The multiplexed, point-of-care measurement of specific antibodies could improve the speed with which diseases are diagnosed and their treatment initiated. To this end, we are developing E-DNA scaffold sensors, which consist of a rigid, nucleic acid "scaffold" attached on one end to an electrode and presenting both a redox reporter and an epitope on the other. In the absence of antibody, the reporter efficiently transfers electrons when interrogated electrochemically. Binding-induced steric hindrance limits movement, reducing electron transfer in a manner that is both easily measured and quantitatively related to target concentration. Previously we have used monoclonal antibodies to explore the analytical performance of E-DNA sensors, showing that they support the rapid, single-step, quantitative detection of multiple antibodies in small volume samples. Here, in contrast, we employ authentic human samples to better explore the platform's clinical potential. Specifically, we developed E-DNA sensors targeting three HIV-specific antibodies and then compared the analytical and clinical performance of these against those of gold standard serological techniques. Doing so we find that, although the multistep amplification of an ELISA leads to a lower detection limits, the clinical sensitivity of ELISAs, E-DNA sensors and lateral-flow dipsticks are indistinguishable across our test set. It thus appears that, by merging the quantitation and multiplexing of ELISAs with the convenience and speed of dipsticks, E-DNA scaffold sensors could significantly improve on current serological practice.
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Affiliation(s)
- Claudio Parolo
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA USA
| | - Ava S. Greenwood
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA USA
| | - Nathan E. Ogden
- Department of Materials, University of California, Santa Barbara, Santa Barbara, CA USA
| | - Di Kang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA USA
| | - Chase Hawes
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA USA
| | - Gabriel Ortega
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA USA
| | | | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA USA
- Interdepartmental Program in Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106 USA
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50
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Idili A, Parolo C, Ortega G, Plaxco KW. Calibration-Free Measurement of Phenylalanine Levels in the Blood Using an Electrochemical Aptamer-Based Sensor Suitable for Point-of-Care Applications. ACS Sens 2019; 4:3227-3233. [PMID: 31789505 PMCID: PMC8097980 DOI: 10.1021/acssensors.9b01703] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
By analogy to the revolution the "home glucose monitor" created in the treatment of diabetes, the availability of a modular, "platform" technology able to measure nearly any metabolite, biomarker, or drug "at-home" in unprocessed, finger-prick volumes of whole blood could revolutionize the monitoring and treatment of disease. Thus motivated, we have adapted here the electrochemical aptamer-based sensing platform to the problem of rapidly and conveniently measuring the level of phenylalanine in the blood, an ability that would aid the monitoring and management of phenylketonuria (PKU). To achieve this, we exploited a previously reported DNA aptamer that recognizes phenylalanine in complex with a rhodium-based "receptor" that improves affinity. We re-engineered this to undergo a large-scale, binding-induced conformational change before modifying it with a methylene blue redox reporter and attaching it to a gold electrode that supports the appropriate electrochemical interrogation. The resultant sensor achieves a useful dynamic range of 90 nM to 7 μM. When challenged with finger-prick-scale sample volumes of the whole blood (diluted 1000-fold to match the sensor's dynamic range), the device achieves the accurate (±20%), calibration-free measurement of blood phenylalanine levels in minutes.
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Affiliation(s)
- Andrea Idili
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Claudio Parolo
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Gabriel Ortega
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Kevin W. Plaxco
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
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