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Liang L, Qin F, Wang S, Wu J, Li R, Wang Z, Ren M, Liu D, Wang D, Astruc D. Overview of the materials design and sensing strategies of nanopore devices. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214998] [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: 12/28/2022]
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Chen P, Sun Z, Wang J, Liu X, Bai Y, Chen J, Liu A, Qiao F, Chen Y, Yuan C, Sha J, Zhang J, Xu LQ, Li J. Portable nanopore-sequencing technology: Trends in development and applications. Front Microbiol 2023; 14:1043967. [PMID: 36819021 PMCID: PMC9929578 DOI: 10.3389/fmicb.2023.1043967] [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] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 01/03/2023] [Indexed: 02/04/2023] Open
Abstract
Sequencing technology is the most commonly used technology in molecular biology research and an essential pillar for the development and applications of molecular biology. Since 1977, when the first generation of sequencing technology opened the door to interpreting the genetic code, sequencing technology has been developing for three generations. It has applications in all aspects of life and scientific research, such as disease diagnosis, drug target discovery, pathological research, species protection, and SARS-CoV-2 detection. However, the first- and second-generation sequencing technology relied on fluorescence detection systems and DNA polymerization enzyme systems, which increased the cost of sequencing technology and limited its scope of applications. The third-generation sequencing technology performs PCR-free and single-molecule sequencing, but it still depends on the fluorescence detection device. To break through these limitations, researchers have made arduous efforts to develop a new advanced portable sequencing technology represented by nanopore sequencing. Nanopore technology has the advantages of small size and convenient portability, independent of biochemical reagents, and direct reading using physical methods. This paper reviews the research and development process of nanopore sequencing technology (NST) from the laboratory to commercially viable tools; discusses the main types of nanopore sequencing technologies and their various applications in solving a wide range of real-world problems. In addition, the paper collates the analysis tools necessary for performing different processing tasks in nanopore sequencing. Finally, we highlight the challenges of NST and its future research and application directions.
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Affiliation(s)
- Pin Chen
- Key Laboratory of DGHD, MOE, School of Life Science and Technology, Southeast University, Nanjing, China
| | - Zepeng Sun
- China Mobile (Chengdu) Industrial Research Institute, Chengdu, China
| | - Jiawei Wang
- School of Computer Science and Technology, Southeast University, Nanjing, China
| | - Xinlong Liu
- China Mobile (Chengdu) Industrial Research Institute, Chengdu, China
| | - Yun Bai
- Key Laboratory of DGHD, MOE, School of Life Science and Technology, Southeast University, Nanjing, China
| | - Jiang Chen
- Key Laboratory of DGHD, MOE, School of Life Science and Technology, Southeast University, Nanjing, China
| | - Anna Liu
- Key Laboratory of DGHD, MOE, School of Life Science and Technology, Southeast University, Nanjing, China
| | - Feng Qiao
- China Mobile (Chengdu) Industrial Research Institute, Chengdu, China
| | - Yang Chen
- Key Laboratory of DGHD, MOE, School of Life Science and Technology, Southeast University, Nanjing, China
| | - Chenyan Yuan
- Clinical Laboratory, Southeast University Zhongda Hospital, Nanjing, China
| | - Jingjie Sha
- School of Mechanical Engineering, Southeast University, Nanjing, China
| | - Jinghui Zhang
- School of Computer Science and Technology, Southeast University, Nanjing, China
| | - Li-Qun Xu
- China Mobile (Chengdu) Industrial Research Institute, Chengdu, China,*Correspondence: Li-Qun Xu, ✉
| | - Jian Li
- Key Laboratory of DGHD, MOE, School of Life Science and Technology, Southeast University, Nanjing, China,Jian Li, ✉
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Leong IW, Kishimoto S, Tsutsui M, Taniguchi M. Interference of electrochemical ion diffusion in nanopore sensing. iScience 2022; 25:105073. [PMID: 36147952 PMCID: PMC9485904 DOI: 10.1016/j.isci.2022.105073] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/06/2022] [Accepted: 08/30/2022] [Indexed: 11/14/2022] Open
Abstract
Stable and fast-responding ionic current is a prerequisite for reliable measurements of small objects with a nanopore. Here, we report on the interference of ion diffusion kinetics at liquid-electrode interfaces in nanopore sensing. Using platinum as electrodes, we observed a slow and large decrease in the ionic current through a nanopore in a salt solution suggestive of the considerable influence of the growing impedance at the liquid-metal interfaces via Cottrell diffusion. When detecting nanoparticles, the resistive pulses became weaker following the steady increase in the resistance at the partially polarizable electrodes. The interfacial impedance was also demonstrated to couple with the nanopore chip capacitance thereby degraded the temporal resolution of the ionic current measurements in a time-varying manner. These findings can be useful for choosing the suitable size and material of electrodes for the single-particle and -molecule analyses by ionic current. Ag/AgCl electrodes enable reliable resistive pulse detections of nanoparticles Pt electrodes induce ionic current decay by time via the Cottrell diffusion Cottrell diffusion deteriorates the nanopore sensor temporal resolution
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Affiliation(s)
- Iat Wai Leong
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Shohei Kishimoto
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
| | - Masateru Taniguchi
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
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4
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Abstract
Tuning capture rates and translocation time of analytes in solid-state nanopores are one of the major challenges for their use in detecting and analyzing individual nanoscale objects via ionic current measurements. Here, we report on the use of salt gradient for the fine control of capture-to-translocation dynamics in 300 nm sized SiNx nanopores. We demonstrated a decrease up to a factor of 3 in the electrophoretic speed of nanoparticles at the pore exit along with an over 3-fold increase in particle detection efficiency by subjecting a 5-fold ion concentration difference across the dielectric membrane. The improvement in the sensor performance was elucidated to be a result of the salt-gradient-mediated electric field and electroosmotic flow asymmetry at nanochannel orifices. The present findings can be used to enhance nanopore sensing capability for detecting biomolecules such as amyloids and proteins.
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Affiliation(s)
- Iat Wai Leong
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Kazumichi Yokota
- National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa 761-0395, Japan
| | - Masateru Taniguchi
- The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
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5
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Abstract
Nanopore technology holds great promise for a wide range of applications such as biomedical sensing, chemical detection, desalination, and energy conversion. For sensing performed in electrolytes in particular, abundant information about the translocating analytes is hidden in the fluctuating monitoring ionic current contributed from interactions between the analytes and the nanopore. Such ionic currents are inevitably affected by noise; hence, signal processing is an inseparable component of sensing in order to identify the hidden features in the signals and to analyze them. This Guide starts from untangling the signal processing flow and categorizing the various algorithms developed to extracting the useful information. By sorting the algorithms under Machine Learning (ML)-based versus non-ML-based, their underlying architectures and properties are systematically evaluated. For each category, the development tactics and features of the algorithms with implementation examples are discussed by referring to their common signal processing flow graphically summarized in a chart and by highlighting their key issues tabulated for clear comparison. How to get started with building up an ML-based algorithm is subsequently presented. The specific properties of the ML-based algorithms are then discussed in terms of learning strategy, performance evaluation, experimental repeatability and reliability, data preparation, and data utilization strategy. This Guide is concluded by outlining strategies and considerations for prospect algorithms.
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Affiliation(s)
- Chenyu Wen
- Division
of Solid-State Electronics, Department of Electrical Engineering, Uppsala University, SE-751 03 Uppsala, Sweden
| | - Dario Dematties
- Instituto
de Ciencias Humanas, Sociales y Ambientales, CONICET Mendoza Technological Scientific Center, Mendoza M5500, Argentina
| | - Shi-Li Zhang
- Division
of Solid-State Electronics, Department of Electrical Engineering, Uppsala University, SE-751 03 Uppsala, Sweden
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6
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Kishimoto S, Tsutsui M, Yokota K, Taniguchi M. Inertial focusing and zeta potential measurements of single-nanoparticles using octet-nanochannels. Lab Chip 2021; 21:3076-3085. [PMID: 34195745 DOI: 10.1039/d1lc00239b] [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] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Capture-to-translocation dynamics control is an important issue for single-particle and -molecule analyses by resistive pulse waveforms. Here, we report on regulated motions for accurate zeta-potential assessments of single nanoscale objects passing through an octet-nanochannel. We observed ionic spike signals consisting of eight consecutive sub-pulses signifying the ion blockage at the eight sensing zones in series upon electrophoretic translocation of individual nanoparticles. We find an exponential decrease to saturation of the channel-to-channel translocation duration as a nanobead moves forward, reflecting the more restricted radial motion degrees of freedom via inertial effects at the downstream side of the octet channel. This finding enabled a protocol for single-nanoparticle zeta potential estimation impervious to the uncertainty stemming from the stochastic nature of the translocation dynamics. The multi-channel approach presented in this study may be used as a useful tool for analyzing particles and molecules of variable sizes.
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Affiliation(s)
- Shohei Kishimoto
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
| | - Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
| | - Kazumichi Yokota
- National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa 761-0395, Japan
| | - Masateru Taniguchi
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
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Abstract
The advent of single-molecule probing techniques has revolutionized the biomedical and life science fields and has spurred the development of a new class of labs-on-chip based on powerful biosensors. Nanopores represent one of the most recent and most promising single molecule sensing paradigms that is seeing increased chip-scale integration for improved convenience and performance. Due to their physical structure, nanopores are highly sensitive, require low sample volume, and offer label-free, amplification-free, high-throughput real-time detection and identification of biomolecules. Over the last 25 years, nanopores have been extensively employed to detect a variety of biomolecules with a growing range of applicatons ranging from nucleic acid sequencing to ultrasensitive diagnostics to single-molecule biophysics. Nanopores, in particular those in solid-state membranes, also have the potential for integration with other technologies such as optics, plasmonics, microfluidics, and optofluidics to perform more complex tasks for an ever-expanding demand. A number of breakthrough results using integrated nanopore platforms have already been reported, and more can be expected as nanopores remain the focus of innovative research and are finding their way into commercial instruments. This review provides an overview of different aspects and challenges of nanopore technology with a focus on chip-scale integration of solid-state nanopores for biosensing and bioanalytical applications.
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Affiliation(s)
- Mahmudur Rahman
- School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064 USA. and Dhaka University of Engineering & Technology, Gazipur, Bangladesh
| | | | - Aaron Hawkins
- ECEn Department, Brigham Young University, 459 Clyde Building, Provo, UT, 84602 USA
| | - Holger Schmidt
- School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064 USA.
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Martínez-Rodríguez F, Limones-González JE, Mendoza-Almanza B, Esparza-Ibarra EL, Gallegos-Flores PI, Ayala-Luján JL, Godina-González S, Salinas E, Mendoza-Almanza G. Understanding Cervical Cancer through Proteomics. Cells 2021; 10:1854. [PMID: 34440623 PMCID: PMC8391734 DOI: 10.3390/cells10081854] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/05/2021] [Accepted: 07/20/2021] [Indexed: 12/17/2022] Open
Abstract
Cancer is one of the leading public health issues worldwide, and the number of cancer patients increases every day. Particularly, cervical cancer (CC) is still the second leading cause of cancer death in women from developing countries. Thus, it is essential to deepen our knowledge about the molecular pathogenesis of CC and propose new therapeutic targets and new methods to diagnose this disease in its early stages. Differential expression analysis using high-throughput techniques applied to biological samples allows determining the physiological state of normal cells and the changes produced by cancer development. The cluster of differential molecular profiles in the genome, the transcriptome, or the proteome is analyzed in the disease, and it is called the molecular signature of cancer. Proteomic analysis of biological samples of patients with different grades of cervical intraepithelial neoplasia (CIN) and CC has served to elucidate the pathways involved in the development and progression of cancer and identify cervical proteins associated with CC. However, several cervical carcinogenesis mechanisms are still unclear. Detecting pathologies in their earliest stages can significantly improve a patient's survival rate, prognosis, and recurrence. The present review is an update on the proteomic study of CC.
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Affiliation(s)
- Fátima Martínez-Rodríguez
- Microbiology Department, Basic Science Center, Autonomous University of Aguascalientes, Aguascalientes 20100, Mexico;
| | | | - Brenda Mendoza-Almanza
- Academic Unit of Biological Sciences, Autonomous University of Zacatecas, Zacatecas 98068, Mexico; (B.M.-A.); (E.L.E.-I.); (P.I.G.-F.)
| | - Edgar L. Esparza-Ibarra
- Academic Unit of Biological Sciences, Autonomous University of Zacatecas, Zacatecas 98068, Mexico; (B.M.-A.); (E.L.E.-I.); (P.I.G.-F.)
| | - Perla I. Gallegos-Flores
- Academic Unit of Biological Sciences, Autonomous University of Zacatecas, Zacatecas 98068, Mexico; (B.M.-A.); (E.L.E.-I.); (P.I.G.-F.)
| | - Jorge L. Ayala-Luján
- Academic Unit of Chemical Sciences, Autonomous University of Zacatecas, Zacatecas 98160, Mexico; (J.L.A.-L.); (S.G.-G.)
| | - Susana Godina-González
- Academic Unit of Chemical Sciences, Autonomous University of Zacatecas, Zacatecas 98160, Mexico; (J.L.A.-L.); (S.G.-G.)
| | - Eva Salinas
- Microbiology Department, Basic Science Center, Autonomous University of Aguascalientes, Aguascalientes 20100, Mexico;
| | - Gretel Mendoza-Almanza
- Master in Biomedical Sciences, Autonomous University of Zacatecas, Zacatecas 98160, Mexico;
- National Council of Science and Technology, Autonomous University of Zacatecas, Zacatecas 98000, Mexico
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Tsutsui M, Takaai T, Yokota K, Kawai T, Washio T. Deep Learning-Enhanced Nanopore Sensing of Single-Nanoparticle Translocation Dynamics. Small Methods 2021; 5:e2100191. [PMID: 34928002 DOI: 10.1002/smtd.202100191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/17/2021] [Indexed: 06/14/2023]
Abstract
Noise is ubiquitous in real space that hinders detection of minute yet important signals in electrical sensors. Here, the authors report on a deep learning approach for denoising ionic current in resistive pulse sensing. Electrophoretically-driven translocation motions of single-nanoparticles in a nano-corrugated nanopore are detected. The noise is reduced by a convolutional auto-encoding neural network, designed to iteratively compare and minimize differences between a pair of waveforms via a gradient descent optimization. This denoising in a high-dimensional feature space is demonstrated to allow detection of the corrugation-derived wavy signals that cannot be identified in the raw curves nor after digital processing in frequency domains under the given noise floor, thereby enabled in-situ tracking to electrokinetic analysis of fast-moving single- and double-nanoparticles. The ability of the unlabeled learning to remove noise without compromising temporal resolution may be useful in solid-state nanopore sensing of protein structure and polynucleotide sequence.
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Affiliation(s)
- Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
| | - Takayuki Takaai
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
| | - Kazumichi Yokota
- National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa, 761-0395, Japan
| | - Tomoji Kawai
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
| | - Takashi Washio
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
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10
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Hayashida T, Tsutsui M, Murayama S, Nakada T, Taniguchi M. Dielectric Coatings for Resistive Pulse Sensing Using Solid-State Pores. ACS Appl Mater Interfaces 2021; 13:10632-10638. [PMID: 33595287 DOI: 10.1021/acsami.0c22548] [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] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The present study reports on the systematic characterization of the effectiveness of dielectric coating to tailor capture-to-translocation dynamics of single particles in solid-state pores. We covered the surface of SiNx membranes with SiO2, HfO2, Al2O3, TiO2, or ZnO, which allowed us to change the ζ-potential at the pore wall, reflecting the isoelectric points of these coating materials. Resistive pulse measurements of negatively charged polystyrene beads elucidated more facile electrophoretic capture of the particles and slower translocation motions in the channel under more negative electric potential at the oxide surface. These findings provide a guide to engineer pore wall surface for optimizing the translocation dynamics for efficient sensing of particles and molecules.
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Affiliation(s)
- Tomoki Hayashida
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Sanae Murayama
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Tomoko Nakada
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Masateru Taniguchi
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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Arima A, Tsutsui M, Washio T, Baba Y, Kawai T. Solid-State Nanopore Platform Integrated with Machine Learning for Digital Diagnosis of Virus Infection. Anal Chem 2020; 93:215-227. [PMID: 33251802 DOI: 10.1021/acs.analchem.0c04353] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Akihide Arima
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Takashi Washio
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Yoshinobu Baba
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.,Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.,Institute of Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, Anagawa 4-9-1, Inage-ku, Chiba 263-8555, Japan
| | - Tomoji Kawai
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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Hattori S, Sekido R, Leong IW, Tsutsui M, Arima A, Tanaka M, Yokota K, Washio T, Kawai T, Okochi M. Machine learning-driven electronic identifications of single pathogenic bacteria. Sci Rep 2020; 10:15525. [PMID: 32968098 DOI: 10.1038/s41598-020-72508-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 09/02/2020] [Indexed: 11/28/2022] Open
Abstract
A rapid method for screening pathogens can revolutionize health care by enabling infection control through medication before symptom. Here we report on label-free single-cell identifications of clinically-important pathogenic bacteria by using a polymer-integrated low thickness-to-diameter aspect ratio pore and machine learning-driven resistive pulse analyses. A high-spatiotemporal resolution of this electrical sensor enabled to observe galvanotactic response intrinsic to the microbes during their translocation. We demonstrated discrimination of the cellular motility via signal pattern classifications in a high-dimensional feature space. As the detection-to-decision can be completed within milliseconds, the present technique may be used for real-time screening of pathogenic bacteria for environmental and medical applications.
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Abstract
Dynamic motions of materials in liquid present a wealth of information concerning their physical properties. While fluorescence microscopy has been widely utilized for single-particle observations, the method cannot be used for characterizing fast motions of nanoscale objects due to the limited spatiotemporal resolution. Here, we report on a nanostructure strategy for nanoscale tracking of single nanoparticles. We fabricated a straight conduit in a SiO2 layer on a Si wafer with lithographically defined 30 nm-sized protrusions formed on the side walls. We performed resistive pulse measurements at a 1 MHz sampling rate wherein we found n-stepped current traces signifying n number of nanoparticles moving concurrently inside the nanochannel. Ensemble average of the ionic current signals revealed a peculiar feature reflecting the slightly stronger ion blockage at the nanoconstrictions between the protrusions, thereby proving the ability of nano-corrugation as physical gates to signify the precise positions of objects inside the nanofluidic channel. This in situ tracking approach elucidated steady-state motions of the nanoparticles moving at a constant speed under the counter-balanced electrophoretic and viscous drag forces, which also allowed estimations of their surface charge densities. The present method can be utilized as a speedometer for nanoscale objects of virtually any size as long as they are able to be put through the sensing zones with potential applications for single-molecule time-of-flight mass spectrometry.
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Affiliation(s)
- Makusu Tsutsui
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Kazumichi Yokota
- National Institute of Advanced Industrial Science and Technology, Takamatsu, Kagawa 761-0395, Japan
| | - Yuhui He
- Huazhong University of Science and Technology, Wuhan 430074, China
| | - Takashi Washio
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Tomoji Kawai
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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