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Geleta GS. A colorimetric aptasensor based on gold nanoparticles for detection of microbial toxins: an alternative approach to conventional methods. Anal Bioanal Chem 2022; 414:7103-7122. [PMID: 35902394 DOI: 10.1007/s00216-022-04227-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 07/06/2022] [Accepted: 07/08/2022] [Indexed: 11/01/2022]
Abstract
Frequent contamination of foods with microbial toxins produced by microorganisms such as bacteria, fungi, and algae represents an increasing public health problem that requires the development of quick and easy tools to detect them at trace levels. Recently, it has been found that colorimetric detection methods may replace traditional methods in the field because of their ease of use, quick response, ease of manufacture, low cost, and naked-eye visibility. Therefore, it is suitable for fieldwork, especially for work in remote areas of the world. However, the development of colorimetric detection methods with low detection limits is a challenge that limits their wide applicability in the detection of food contaminants. To address these challenges, nanomaterial-based transduction systems are used to construct colorimetric biosensors. For example, gold nanoparticles (AuNPs) provide an excellent platform for the development of colorimetric biosensors because they offer the advantages of easy synthesis, biocompatibility, advanced surface functionality, and adjustable physicochemical properties. The selectivity of the colorimetric biosensor can be achieved by the combination of aptamers and gold nanoparticles, which provides an unprecedented opportunity to detect microbial toxins. Compared to antibodies, aptamers have significant advantages in the analysis of microbial toxins due to their smaller size, higher binding affinity, reproducible chemical synthesis and modification, stability, and specificity. Two colorimetric mechanisms for the detection of microbial toxins based on AuNPs have been described. First, sensors that use the localized surface plasmon resonance (LSPR) phenomenon of gold nanoparticles can exhibit very strong colors in the visible range because of changes caused by aggregation or disaggregation. Second, the detection mechanism of AuNPs is based on their enzyme mimetic properties and it is possible to construct a colorimetric biosensor based on the 3,3',5,5'-tetramethylbenzidine/Hydrogen peroxide, TMB/H2O2 reaction to detect microbial toxins. Therefore, this review summarizes the recent applications of AuNP-based colorimetric aptasensors for detecting microbial toxins, including bacterial toxins, fungal toxins, and algal toxins focusing on selectivity, sensitivity, and practicality. Finally, the most important current challenges in this field and future research opportunities are discussed.
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Affiliation(s)
- Girma Salale Geleta
- Department of Chemistry, College of Natural Sciences, Salale University, P.O. Box 245, Oromia, Fiche, Ethiopia.
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Ajala S, Muraleedharan Jalajamony H, Nair M, Marimuthu P, Fernandez RE. Comparing machine learning and deep learning regression frameworks for accurate prediction of dielectrophoretic force. Sci Rep 2022; 12:11971. [PMID: 35831342 PMCID: PMC9279499 DOI: 10.1038/s41598-022-16114-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 07/05/2022] [Indexed: 11/09/2022] Open
Abstract
An intelligent sensing framework using Machine Learning (ML) and Deep Learning (DL) architectures to precisely quantify dielectrophoretic force invoked on microparticles in a textile electrode-based DEP sensing device is reported. The prediction accuracy and generalization ability of the framework was validated using experimental results. Images of pearl chain alignment at varying input voltages were used to build deep regression models using modified ML and CNN architectures that can correlate pearl chain alignment patterns of Saccharomyces cerevisiae(yeast) cells and polystyrene microbeads to DEP force. Various ML models such as K-Nearest Neighbor, Support Vector Machine, Random Forest, Neural Networks, and Linear Regression along with DL models such as Convolutional Neural Network (CNN) architectures of AlexNet, ResNet-50, MobileNetV2, and GoogLeNet have been analyzed in order to build an effective regression framework to estimate the force induced on yeast cells and microbeads. The efficiencies of the models were evaluated using Mean Absolute Error, Mean Absolute Relative, Mean Squared Error, R-squared, and Root Mean Square Error (RMSE) as evaluation metrics. ResNet-50 with RMSPROP gave the best performance, with a validation RMSE of 0.0918 on yeast cells while AlexNet with ADAM optimizer gave the best performance, with a validation RMSE of 0.1745 on microbeads. This provides a baseline for further studies in the application of deep learning in DEP aided Lab-on-Chip devices.
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Affiliation(s)
- Sunday Ajala
- Department of Engineering, Norfolk State University, Norfolk, USA
| | | | - Midhun Nair
- APJ Abdul Kalam Technological University, Thiruvananthapuram, India
| | - Pradeep Marimuthu
- Rajeev Gandhi College of Engineering and Technology, Puducherry, India
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Deep-Learning Based Estimation of Dielectrophoretic Force. MICROMACHINES 2021; 13:mi13010041. [PMID: 35056207 PMCID: PMC8779967 DOI: 10.3390/mi13010041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/24/2021] [Accepted: 12/26/2021] [Indexed: 11/22/2022]
Abstract
The ability to accurately quantify dielectrophoretic (DEP) force is critical in the development of high-efficiency microfluidic systems. This is the first reported work that combines a textile electrode-based DEP sensing system with deep learning in order to estimate the DEP forces invoked on microparticles. We demonstrate how our deep learning model can process micrographs of pearl chains of polystyrene (PS) microbeads to estimate the DEP forces experienced. Numerous images obtained from our experiments at varying input voltages were preprocessed and used to train three deep convolutional neural networks, namely AlexNet, MobileNetV2, and VGG19. The performances of all the models was tested for their validation accuracies. Models were also tested with adversarial images to evaluate performance in terms of classification accuracy and resilience as a result of noise, image blur, and contrast changes. The results indicated that our method is robust under unfavorable real-world settings, demonstrating that it can be used for the direct estimation of dielectrophoretic force in point-of-care settings.
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Hobbs RJ, Thomas CA, Halliwell J, Gwenin CD. Rapid Detection of Botulinum Neurotoxins-A Review. Toxins (Basel) 2019; 11:E418. [PMID: 31319550 PMCID: PMC6669533 DOI: 10.3390/toxins11070418] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/15/2019] [Accepted: 07/15/2019] [Indexed: 12/13/2022] Open
Abstract
A toxin is a poisonous substance produced within living cells or organisms. One of the most potent groups of toxins currently known are the Botulinum Neurotoxins (BoNTs). These are so deadly that as little as 62 ng could kill an average human; to put this into context that is approximately 200,000 × less than the weight of a grain of sand. The extreme toxicity of BoNTs leads to the need for methods of determining their concentration at very low levels of sensitivity. Currently the mouse bioassay is the most widely used detection method monitoring the activity of the toxin; however, this assay is not only lengthy, it also has both cost and ethical issues due to the use of live animals. This review focuses on detection methods both existing and emerging that remove the need for the use of animals and will look at three areas; speed of detection, sensitivity of detection and finally cost. The assays will have wide reaching interest, ranging from the pharmaceutical/clinical industry for production quality management or as a point of care sensor in suspected cases of botulism, the food industry as a quality control measure, to the military, detecting BoNT that has been potentially used as a bio warfare agent.
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Affiliation(s)
- Robert J Hobbs
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Carol A Thomas
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Jennifer Halliwell
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK
| | - Christopher D Gwenin
- Applied Research in Chemistry and Health (ARCH) Research Group, School of Natural Sciences, Bangor University, Bangor, Gwynedd, Wales LL57 2UW, UK.
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Eivazzadeh-Keihan R, Pashazadeh-Panahi P, Baradaran B, Guardia MDL, Hejazi M, Sohrabi H, Mokhtarzadeh A, Maleki A. Recent progress in optical and electrochemical biosensors for sensing of Clostridium botulinum neurotoxin. Trends Analyt Chem 2018. [DOI: 10.1016/j.trac.2018.03.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Reddy PN, Srirama K, Dirisala VR. An Update on Clinical Burden, Diagnostic Tools, and Therapeutic Options of Staphylococcus aureus. Infect Dis (Lond) 2017; 10:1179916117703999. [PMID: 28579798 PMCID: PMC5443039 DOI: 10.1177/1179916117703999] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 03/18/2017] [Indexed: 12/26/2022] Open
Abstract
Staphylococcus aureus is an important pathogen responsible for a variety of diseases ranging from mild skin and soft tissue infections, food poisoning to highly serious diseases such as osteomyelitis, endocarditis, and toxic shock syndrome. Proper diagnosis of pathogen and virulence factors is important for providing timely intervention in the therapy. Owing to the invasive nature of infections and the limited treatment options due to rampant spread of antibiotic-resistant strains, the trend for development of vaccines and antibody therapy is increasing at rapid rate than development of new antibiotics. In this article, we have discussed elaborately about the host-pathogen interactions, clinical burden due to S aureus infections, status of diagnostic tools, and treatment options in terms of prophylaxis and therapy.
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Low-Cost Charged-Coupled Device (CCD) Based Detectors for Shiga Toxins Activity Analysis. Methods Mol Biol 2017. [PMID: 28281260 DOI: 10.1007/978-1-4939-6848-0_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
To improve food safety there is a need to develop simple, low-cost sensitive devices for detection of food-borne pathogens and their toxins. We describe a simple, low-cost webcam-based detector which can be used for various optical detection modalities, including fluorescence, chemiluminescence, densitometry, and colorimetric assays. The portable battery-operated CCD-based detection system consists of four modules: (1) a webcam to measure and record light emission, (2) a sample plate to perform assays, (3) a light emitting diode (LED) for illumination, and (4) a portable computer to acquire and analyze images. To demonstrate the technology, we used a cell based assay for fluorescence detection of the activity of the food borne Shiga toxin type 2 (Stx2), differentiating between biologically active toxin and inactive toxin which is not a risk. The assay is based on Shiga toxin inhibition of cell protein synthesis measured through inhibition of the green fluorescent protein (GFP). In this assay, GFP emits light at 509 nm when excited with a blue LED equipped with a filter at 486 nm. The emitted light is then detected with a green filter at 535 nm. Toxin activity is measured through a reduction in the 509 nm emission. In this system the level of detection (LOD) for Stx2 was 0.1 pg/ml, similar to the LOD of commercial fluorometers. These results demonstrate the utility and potential of low cost detectors for toxin activity. This approach could be readily adapted to the detection of other food-borne toxins.
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Taitt CR, Anderson GP, Ligler FS. Evanescent wave fluorescence biosensors: Advances of the last decade. Biosens Bioelectron 2016; 76:103-12. [PMID: 26232145 PMCID: PMC5012222 DOI: 10.1016/j.bios.2015.07.040] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/15/2015] [Accepted: 07/18/2015] [Indexed: 12/12/2022]
Abstract
Biosensor development has been a highly dynamic field of research and has progressed rapidly over the past two decades. The advances have accompanied the breakthroughs in molecular biology, nanomaterial sciences, and most importantly computers and electronics. The subfield of evanescent wave fluorescence biosensors has also matured dramatically during this time. Fundamentally, this review builds on our earlier 2005 review. While a brief mention of seminal early work will be included, this current review will focus on new technological developments as well as technology commercialized in just the last decade. Evanescent wave biosensors have found a wide array applications ranging from clinical diagnostics to biodefense to food testing; advances in those applications and more are described herein.
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Affiliation(s)
- Chris Rowe Taitt
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375-5348, USA
| | - George P Anderson
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375-5348, USA
| | - Frances S Ligler
- UNC-Chapel Hill and NC State University Department of Biomedical Engineering, 911 Oval Drive, Raleigh, NC 27695-7115, USA.
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Saravanan P, Rajaseger G, Eric YPH, Moochhala S. Botulinum Toxin: Present Knowledge and Threats. BIOLOGICAL TOXINS AND BIOTERRORISM 2015. [DOI: 10.1007/978-94-007-5869-8_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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10
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Gel pad array chip for high throughput and multi-analyte microbead-based immunoassays. Biosens Bioelectron 2014; 66:370-8. [PMID: 25463645 DOI: 10.1016/j.bios.2014.10.083] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 09/17/2014] [Accepted: 10/09/2014] [Indexed: 11/20/2022]
Abstract
We present here a gel pad array chip for high-throughput and multi-analyte microbead-based immunoassays. The chip is fabricated by photo-patterning of two polymeric gels, polyacrylamide gel and polyethylene glycol (PEG) gel, on a glass slide. The resulting chip consists of 40 polyacrylamide gel pad array units for the immobilization of microbeads and each gel pad array is surrounded with a PEG micropillar ring to confine the samples within the microarray. As a proof of concept, this chip was tested for quantitative immunoassays for two model cancer markers, human chorionic gonadotropin (hCG) and prostate specific antigen (PSA), in serum samples. Detection limits below the physiological threshold level for cancer diagnosis were achieved with good inter- and intra-chip reproducibility. Moreover, by using spatial encoded microbeads, simultaneous detection of both hCG and PSA on each gel pad array is achieved with single filter fluorescence imaging. This gel pad array chip is easy to use, easy to fabricate with low cost materials and minimal equipment and reusable. It could be a useful tool for common biolabs to customize their own microbead array for multi-analyte immunoassays.
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12
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Sachdeva A, Singh AK, Sharma SK. An electrochemiluminescence assay for the detection of bio threat agents in selected food matrices and in the screening of Clostridium botulinum outbreak strains associated with type A botulism. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2014; 94:707-712. [PMID: 23873138 DOI: 10.1002/jsfa.6310] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 05/02/2013] [Accepted: 07/19/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Specific screening methods for complex food matrices are needed that enable unambiguous and sensitive detection of bio threat agents (BTAs) such as Bacillus anthracis spores and microbial toxins (e.g. staphylococcal enterotoxin B (SEB) and clostridial botulinum neurotoxins (BoNTs)). The present study describes an image-based 96-well Meso Scale Discovery (MSD) electrochemiluminescence (ECL) assay for simultaneous detection of BTAs in dairy milk products. RESULTS The limit of detection of this ECL assay is 40 pg mL⁻¹ for BoNT/A complex, 10 pg mL⁻¹ for SEB and 40000 CFU mL⁻¹ for Bacillus anthracis spores in dairy milk products. The ECL assay was successfully applied to screen type A Clostridium botulinum outbreak strains. CONCLUSION The results of the study indicate that this ECL assay is very sensitive, rapid (<6 h) and multiplex in nature. The ECL assay has potential for use as an in vitro screening method for BTAs over other comparable immunoassays.
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Affiliation(s)
- Amita Sachdeva
- Division of Microbiology, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, 5100 Paint Branch Parkway, College Park, MD, 20740, USA
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Rasooly A, Kostov Y, Bruck HA. Charged-coupled device (CCD) detectors for Lab-on-a Chip (LOC) optical analysis. Methods Mol Biol 2013; 949:365-385. [PMID: 23329454 DOI: 10.1007/978-1-62703-134-9_23] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A critical element of any Lab-on-a-Chip (LOC) is a detector; among the many detection approaches, optical detection is very widely used for biodetection. One challenge for advancing the development of LOC for biodetection has been to enhance the portability and lower the cost for Point-of-Care diagnostics, which has the potential to enhance the quality of healthcare delivery for underserved populations and for global health. We describe a simple and relatively low cost charged-coupled device (CCD)-based detector that can be integrated with a conventional microtiter plate or a portable LOC assay for various optical detection modalities including fluorescence, chemiluminescence, densitometry, and colorimetric assays. In general, the portable battery-operated CCD-based detection system consists of four modules: (1) a cooled CCD digital camera to monitor light emission, (2) a LOC or microtiter plate to perform assays, (3) a light source to illuminate the assay (such as electroluminescence (EL) or light emitting diode (LED)), and (4) a portable computer to acquire and analyze images. The configuration of the fluorescence detector presented here was designed to measure fluorogenic excitation at 490 nm and to monitor emission at 523 nm used for FITC detection.The LOC used for this detection system was fabricated with laminated object manufacturing (LOM) technology, and was designed to detection activity of botulinum neurotoxin serotype A (BoNT-A) using a fluorogenic peptide substrate (SNAP-25) for botulinum neurotoxin serotype A (BoNT-A) labeled with FITC. The limit of detection (LOD) for the CCD detector is 0.5 nM (25 ng/ml). The portable system is small and is powered by a 12 V source. The modular detector was designed with easily interchangeable LEDs, ELs, filters, lenses, and LOC, and can be used and adapted for a wide variety of densitometry, florescence and colorimetric assays.
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Affiliation(s)
- Avraham Rasooly
- Division of Biology, Office of Science and Engineering, FDA Center for Devices and Radiological Health (CDRH), Silver Spring, MD, USA.
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Kirsch J, Siltanen C, Zhou Q, Revzin A, Simonian A. Biosensor technology: recent advances in threat agent detection and medicine. Chem Soc Rev 2013; 42:8733-68. [DOI: 10.1039/c3cs60141b] [Citation(s) in RCA: 313] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Narsaiah K, Jha SN, Bhardwaj R, Sharma R, Kumar R. Optical biosensors for food quality and safety assurance-a review. JOURNAL OF FOOD SCIENCE AND TECHNOLOGY 2012; 49:383-406. [PMID: 23904648 PMCID: PMC3550887 DOI: 10.1007/s13197-011-0437-6] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 06/08/2011] [Accepted: 06/14/2011] [Indexed: 01/18/2023]
Abstract
Food quality and safety is a scientific discipline describing handling, preparation and storage of food in ways that prevent food borne illness. Food serves as a growth medium for microorganisms that can be pathogenic or cause food spoilage. Therefore, it is imperative to have stringent laws and standards for the preparation, packaging and transportation of food. The conventional methods for detection of food contamination based on culturing, colony counting, chromatography and immunoassay are tedious and time consuming while biosensors have overcome some of these disadvantages. There is growing interest in biosensors due to high specificity, convenience and quick response. Optical biosensors show greater potential for the detection of pathogens, pesticide and drug residues, hygiene monitoring, heavy metals and other toxic substances in the food to check whether it is safe for consumption or not. This review focuses on optical biosensors, the recent developments in the associated instrumentation with emphasis on fiber optic and surface plasmon resonance (SPR) based biosensors for detecting a range of analytes in food samples, the major advantages and challenges associated with optical biosensors. It also briefly covers the different methods employed for the immobilization of bio-molecules used in developing biosensors.
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Affiliation(s)
- K. Narsaiah
- Agricultural Structures and Environmental Control Division, Central Institute of Post-harvest Engineering and Technology, Ludhiana, 141004 India
| | - Shyam Narayan Jha
- Agricultural Structures and Environmental Control Division, Central Institute of Post-harvest Engineering and Technology, Ludhiana, 141004 India
| | - Rishi Bhardwaj
- Agricultural Structures and Environmental Control Division, Central Institute of Post-harvest Engineering and Technology, Ludhiana, 141004 India
| | - Rajiv Sharma
- Agricultural Structures and Environmental Control Division, Central Institute of Post-harvest Engineering and Technology, Ludhiana, 141004 India
| | - Ramesh Kumar
- Agricultural Structures and Environmental Control Division, Central Institute of Post-harvest Engineering and Technology, Ludhiana, 141004 India
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Singh AK, Stanker LH, Sharma SK. Botulinum neurotoxin: where are we with detection technologies? Crit Rev Microbiol 2012; 39:43-56. [PMID: 22676403 DOI: 10.3109/1040841x.2012.691457] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Because of its high toxicity, botulinum neurotoxin (BoNT) poses a significant risk to humans and it represents a possible biological warfare agent. Nevertheless, BoNT serotypes A and B are considered an effective treatment for a variety of neurological disorders. The growing applicability of BoNT as a drug, and its potential use as a biological threat agent, highlight the urgent need to develop sensitive detection assays and therapeutic counter measures. In the last decade, significant progress has been made in BoNT detection technologies but none have fully replaced the mouse lethality assay, the current "gold standard". Recently, new advances in robotics and the availability of new reagents have allowed development of methods for rapid toxin analysis. These technologies while promising need further refinement.
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Affiliation(s)
- Ajay K Singh
- Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD 20740, USA
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Agrawal R, Singh PK, Sharma SK, Kamboj DV, Goel AK, Singh L. Highly Expressed Recombinant SEB for Antibody Production and Development of Immunodetection System. Indian J Microbiol 2012; 52:191-6. [PMID: 23729881 PMCID: PMC3386450 DOI: 10.1007/s12088-011-0173-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 03/08/2011] [Indexed: 10/18/2022] Open
Abstract
Staphylococcal enterotoxins (SEs) are the second most common causal agents of food poisoning throughout the world. Staphylococcal enterotoxin B (SEB) is one of the most potent and a listed biological warfare agent. Therefore, its quick, accurate and sensitive detection is of paramount importance. But availability of sensitive and specific antibodies against SEB is the major bottleneck in the development of an immunodetection system. Therefore, in the present study seb gene was cloned and expressed in a heterologous host resulting in a yield of 92 mg pure toxin per litre of culture broth after Ni-NTA affinity purification. Antibodies raised against the recombinant toxin did not cross react with related enterotoxins and organisms that can gain access in the food. Further, a sandwich ELISA was developed to detect SEB after extraction from artificially spiked food samples like milk, orange juice, skim milk and khoya. The sandwich ELISA was able to detect SEB in the range of 0.25 to 0.49 ng/ml or g of food. The detection system developed in the present study is at least as specific and sensitive as other commercially available kits which use monoclonal antibodies.
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Affiliation(s)
- Ranu Agrawal
- Defence Research & Development Establishment, Gwalior, Madhya Pradesh India
| | - Pawan Kumar Singh
- Defence Research & Development Establishment, Gwalior, Madhya Pradesh India
| | | | - D. V. Kamboj
- Defence Research & Development Establishment, Gwalior, Madhya Pradesh India
| | - Ajay Kumar Goel
- Defence Research & Development Establishment, Gwalior, Madhya Pradesh India
| | - Lokendra Singh
- Defence Research & Development Establishment, Gwalior, Madhya Pradesh India
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A bioanalytical platform for simultaneous detection and quantification of biological toxins. SENSORS 2012; 12:2324-39. [PMID: 22438766 PMCID: PMC3304168 DOI: 10.3390/s120202324] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 02/09/2012] [Accepted: 02/20/2012] [Indexed: 12/17/2022]
Abstract
Prevalent incidents support the notion that toxins, produced by bacteria, fungi, plants or animals are increasingly responsible for food poisoning or intoxication. Owing to their high toxicity some toxins are also regarded as potential biological warfare agents. Accordingly, control, detection and neutralization of toxic substances are a considerable economic burden to food safety, health care and military biodefense. The present contribution describes a new versatile instrument and related procedures for array-based simultaneous detection of bacterial and plant toxins using a bioanalytical platform which combines the specificity of covalently immobilized capture probes with a dedicated instrumentation and immuno-based microarray analytics. The bioanalytical platform consists of a microstructured polymer slide serving both as support of printed arrays and as incubation chamber. The platform further includes an easy-to-operate instrument for simultaneous slide processing at selectable assay temperature. Cy5 coupled streptavidin is used as unifying fluorescent tracer. Fluorescence image analysis and signal quantitation allow determination of the toxin's identity and concentration. The system's performance has been investigated by immunological detection of Botulinum Neurotoxin type A (BoNT/A), Staphylococcal enterotoxin B (SEB), and the plant toxin ricin. Toxins were detectable at levels as low as 0.5-1 ng · mL(-1) in buffer or in raw milk.
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Dorner MB, Schulz KM, Kull S, Dorner BG. Complexity of Botulinum Neurotoxins: Challenges for Detection Technology. Curr Top Microbiol Immunol 2012. [DOI: 10.1007/978-3-662-45790-0_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Optimizing two-color semiconductor nanocrystal immunoassays in single well microtiter plate formats. SENSORS 2011; 11:7879-91. [PMID: 22164051 PMCID: PMC3231742 DOI: 10.3390/s110807879] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 07/29/2011] [Accepted: 08/01/2011] [Indexed: 11/16/2022]
Abstract
The simultaneous detection of two analytes, chicken IgY (IgG) and Staphylococcal enterotoxin B (SEB), in the single well of a 96-well plate is demonstrated using luminescent semiconductor quantum dot nanocrystal (NC) tracers. The NC-labeled antibodies were prepared via sulfhydryl-reactive chemistry using a facile protocol that took <3 h. Dose response curves for each target were evaluated in a single immunoassay format and compared to Cy5, a fluorophore commonly used in fluorescent immunoassays, and found to be equivalent. Immunoassays were then performed in a duplex format, demonstrating multiplex detection in a single well with limits of detection equivalent to the single assay format: 9.8 ng/mL chicken IgG and 7.8 ng/mL SEB.
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Yang M, Bruck HA, Kostov Y, Rasooly A. Biological semiconductor based on electrical percolation. Anal Chem 2010; 82:3567-72. [PMID: 20361741 DOI: 10.1021/ac902644z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have developed a novel biological semiconductor (BSC) based on electrical percolation through a multilayer three-dimensional carbon nanotube-antibody bionanocomposite network, which can measure biological interactions directly and electronically. In electrical percolation, the passage of current through the conductive network is dependent upon the continuity of the network. Molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. A BSC is fabricated by immobilizing a prefunctionalized single-walled carbon nanotubes (SWNTs)-antibody bionanocomposite directly on a poly(methyl methacrylate) (PMMA) surface (also known as plexiglass or acrylic). We used the BSC for direct (label-free) electronic measurements of antibody-antigen binding, showing that, at slightly above the electrical percolation threshold of the network, binding of a specific antigen dramatically increases the electrical resistance. Using anti-staphylococcal enterotoxin B (SEB) IgG as a "gate" and SEB as an "actuator", we demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/mL. The new BSCs may permit assembly of multiple sensors on the same chip to create "biological central processing units (CPUs)" with multiple BSC elements, capable of processing and sorting out information on multiple analytes simultaneously.
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Affiliation(s)
- Minghui Yang
- Center for Advanced Sensor Technology, University of Maryland, Baltimore County, Maryland 21250, USA
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Yang M, Sun S, Bruck HA, Kostov Y, Rasooly A. Electrical percolation-based biosensor for real-time direct detection of staphylococcal enterotoxin B (SEB). Biosens Bioelectron 2010; 25:2573-8. [PMID: 20447819 PMCID: PMC2996829 DOI: 10.1016/j.bios.2010.04.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 04/14/2010] [Accepted: 04/15/2010] [Indexed: 11/20/2022]
Abstract
Electrical percolation-based biosensing is a new technology. This is the first report of an electrical percolation-based biosensor for real-time detection. The label-free biosensor is based on electrical percolation through a single-walled carbon nanotubes (SWNTs)-antibody complex that forms a network functioning as a "Biological Semiconductor" (BSC). The conductivity of a BSC is directly related to the number of contacts facilitated by the antibody-antigen "connectors" within the SWNT network. BSCs are fabricated by immobilizing a pre-functionalized SWNTs-antibody complex directly on a poly(methyl methacrylate) (PMMA) and polycarbonate (PC) surface. Each BSC is connected via silver electrodes to a computerized ohmmeter, thereby enabling a continuous electronic measurement of molecular interactions (e.g. antibody-antigen binding) via the change in resistance. Using anti-staphylococcal enterotoxin B (SEB) IgG to functionalize the BSC, we demonstrate that the biosensor was able to detect SEB at concentrations as low as 5 ng/mL at a signal to baseline (S/B) ratio of 2. Such measurements were performed on the chip in wet conditions. The actuation of the chip by SEB is immediate, permitting real-time signal measurements. In addition to this "direct" label-free detection mode, a secondary antibody can be used to "label" the target molecule bound to the BSC in a manner analogous to an immunological sandwich "indirect" detection-type assay. Although a secondary antibody is not needed for direct detection, the indirect mode of detection may be useful as an additional measurement to verify or amplify signals from direct detection in clinical, food safety and other critical assays. The BSC was used to measure SEB both in buffer and in milk, a complex matrix, demonstrating the potential of electrical percolation-based biosensors for real-time label-free multi-analyte detection in clinical and complex samples. Assembly of BSCs is simple enough that multiple sensors can be fabricated on the same chip, thereby creating "Biological Central Processing Units (BCPUs)" capable of parallel processing and sorting out information on multiple analytes simultaneously which may be used for complex analysis and for point of care diagnostics.
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Affiliation(s)
- Minghui Yang
- Center for Advanced Sensor Technology, University of Maryland Baltimore County, MD 21250
- School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China
| | - Steven Sun
- Center for Advanced Sensor Technology, University of Maryland Baltimore County, MD 21250
- Division of Biology, Office of Science and Engineering, FDA, Silver Spring, MD 20993
| | - Hugh Alan Bruck
- University of Maryland College Park (UMCP), College Park MD 20742
| | - Yordan Kostov
- Center for Advanced Sensor Technology, University of Maryland Baltimore County, MD 21250
| | - Avraham Rasooly
- Division of Biology, Office of Science and Engineering, FDA, Silver Spring, MD 20993
- National Cancer Institute, Bethesda, MD 20892
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Soto CM, Ratna BR. Virus hybrids as nanomaterials for biotechnology. Curr Opin Biotechnol 2010; 21:426-38. [PMID: 20688511 DOI: 10.1016/j.copbio.2010.07.004] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 07/06/2010] [Accepted: 07/06/2010] [Indexed: 12/24/2022]
Abstract
The current review describes advances in the field of bionanotechnology in which viruses are used to fabricate nanomaterials. Viruses are introduced as protein cages, scaffolds, and templates for the production of biohybrid nanostructured materials where organic and inorganic molecules are incorporated in a precise and a controlled fashion. Genetic engineering enables the insertion or replacement of selected amino acids on virus capsids for uses from bioconjugation to crystal growth. The variety of nanomaterials generated in rod-like and spherical viruses is highlighted for tobacco mosaic virus (TMV), M13 bacteriophage, cowpea chlorotic mottle virus (CCMV), and cowpea mosaic virus (CPMV). Functional biohybrid nanomaterials find applications in biosensing, memory devices, nanocircuits, light-harvesting systems, and nanobatteries.
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Affiliation(s)
- Carissa M Soto
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375, USA.
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24
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Llama-derived single-domain antibodies for the detection of botulinum A neurotoxin. Anal Bioanal Chem 2010; 398:339-48. [PMID: 20582697 DOI: 10.1007/s00216-010-3905-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 06/03/2010] [Accepted: 06/07/2010] [Indexed: 01/28/2023]
Abstract
Single-domain antibodies (sdAb) specific for botulinum neurotoxin serotype A (BoNT A) were selected from an immune llama phage display library derived from a llama that was immunized with BoNT A toxoid. The constructed phage library was panned using two methods: panning on plates coated with BoNT A toxoid (BoNT A Td) and BoNT A complex toxoid (BoNT Ac Td) and panning on microspheres coupled to BoNT A Td and BoNT A toxin (BoNT A Tx). Both panning methods selected for binders that had identical sequences, suggesting that panning on toxoided material may be as effective as panning on bead-immobilized toxin for isolating specific binders. All of the isolated binders tested were observed to recognize bead-immobilized BoNT A Tx in direct binding assays, and showed very little cross-reactivity towards other BoNT serotypes and unrelated protein. Sandwich assays that incorporated selected sdAb as capture and tracer elements demonstrated that all of the sdAb were able to recognize soluble ("live") BoNT A Tx and BoNT Ac Tx with virtually no cross-reactivity with other BoNT serotypes. The isolated sdAb did not exhibit the high degree of thermal stability often associated with these reagents; after the first heating cycle most of the binding activity was lost, but the portion of the protein that did refold and recover antigen-binding activity showed only minimal loss on subsequent heating and cooling cycles. The binding kinetics of selected binders, assessed by both an equilibrium fluid array assay as well as surface plasmon resonance (SPR) using toxoided material, gave dissociation constants (K(D)) in the range 2.2 x 10(-11) to 1.6 x 10(-10) M. These high-affinity binders may prove beneficial to the development of recombinant reagents for the rapid detection of BoNT A, particularly in field screening and monitoring applications.
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Lian W, Wu D, Lim DV, Jin S. Sensitive detection of multiplex toxins using antibody microarray. Anal Biochem 2010; 401:271-9. [DOI: 10.1016/j.ab.2010.02.040] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 02/03/2010] [Accepted: 02/25/2010] [Indexed: 11/28/2022]
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Multiplexed magnetic microsphere immunoassays for detection of pathogens in foods. ACTA ACUST UNITED AC 2010; 4:73-81. [PMID: 20953301 DOI: 10.1007/s11694-010-9097-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Foodstuffs have traditionally been challenging matrices for conducting immunoassays. Proteins, carbohydrates, and other macromolecules present in food matrices may interfere with both immunoassays and PCR-based tests, and removal of particulate matter may also prove challenging prior to analyses. This has been found true when testing for bacterial contamination of foods using the standard polystyrene microspheres utilized with Luminex flow cytometers. Luminex MagPlex microspheres are encoded with the same dyes as standard xMAP microspheres, but have superparamagnetic properties to aid in preparation of samples in complex matrices. In this work, we present results demonstrating use of MagPlex for sample preparation and identification of bacteria and a toxin spiked into a variety of food samples. Fluorescence-coded MagPlex microsphere sets coated with antibodies for Salmonella, Campylobacter, Escherichia coli, Listeria, and staphylococcal enterotoxin B (SEB) were used to capture these bacteria and toxin from spiked foodstuffs and then evaluated by the Luminex system in a multiplex format; spiked foods included apple juice, green pepper, tomato, ground beef, alfalfa sprouts, milk, lettuce, spinach, and chicken washes. Although MagPlex microspheres facilitated recovery of the microspheres and targets from the complex matrices, assay sensitivity was sometimes inhibited by up to one to three orders of magnitude; for example the detection limits E. coli spiked into apple juice or milk increased 100-fold, from 1000 to 100,000 cfu/mL. Thus, while the magnetic and fluorescent properties of the Luminex MagPlex microspheres allow for rapid, multiplexed testing for bacterial contamination in typically problematic food matrices, our data demonstrate that achieving desired limits of detection is still a challenge.
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Sun S, Francis J, Sapsford KE, Kostov Y, Rasooly A. Multi-wavelength Spatial LED illumination based detector for in vitro detection of Botulinum Neurotoxin A Activity. SENSORS AND ACTUATORS. B, CHEMICAL 2010; 146:297-306. [PMID: 20498728 PMCID: PMC2874159 DOI: 10.1016/j.snb.2010.02.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A portable and rapid detection system for the activity analysis of Botulinum Neurotoxins (BoNT) is needed for food safety and bio-security applications. To improve BoNT activity detection, a previously designed portable charge-coupled device (CCD) based detector was modified and equipped with a higher intensity more versatile multi-wavelength spatial light-emitting diode (LED) illumination, a faster CCD detector and the capability to simultaneously detect 30 samples. A FITC/DABCYL Förster Resonance Energy Transfer (FRET)-labeled peptide substrate (SNAP-25), with BoNT-A target cleavage site sequence was used to measure BoNT-A light chain (LcA) activity through the FITC fluorescence increase that occurs upon peptide substrate cleavage. For fluorescence excitation, a multi-wavelength spatial LED illuminator was used and compared to our previous electroluminescent (EL) strips. The LED illuminator was equipped with blue, green, red and white LEDs, covering a spectrum of 450-680 nm (red 610-650 nm, green 492-550 nm, blue 450-495 nm, and white LED 440-680 nm). In terms of light intensity, the blue LED was found to be ~80 fold higher than the previously used blue EL strips. When measuring the activity of LcA the CCD detector limit of detection (LOD) was found to be 0.08 nM LcA for both the blue LED (2 s exposure) and the blue EL (which require ≥60 s exposure) while the limits of quantitation (LOQ) is about 1 nM. The LOD for white LED was higher at 1.4 nM while the white EL was not used for the assay due to a high variable background. Unlike the weaker intensity EL illumination the high intensity LED illumination enabled shorter exposure times and allowed multi-wavelength illumination without the need to physically change the excitation strip, thus making spectrum excitation of multiple fluorophores possible increasing the versatility of the detector platform for a variety of optical detection assays.
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Affiliation(s)
- Steven Sun
- Division of Biology, Office of Science and Engineering Laboratories, FDA, Silver Spring, MD 20993, USA
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Wojciechowski J, Danley D, Cooper J, Yazvenko N, Taitt CR. Multiplexed electrochemical detection of Yersinia pestis and staphylococcal enterotoxin B using an antibody microarray. SENSORS (BASEL, SWITZERLAND) 2010; 10:3351-62. [PMID: 22319302 PMCID: PMC3274223 DOI: 10.3390/s100403351] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 02/28/2010] [Accepted: 03/26/2010] [Indexed: 11/24/2022]
Abstract
The CombiMatrix antibody microarray is a versatile, sensitive detection platform based on the generation and transduction of electrochemical signals following antigen binding to surface antibodies. The sensor chip described herein is comprised of microelectrodes coupled to an adjacent bio-friendly matrix coated with antibodies to the biological pathogens Yersinia pestis and Bacillus anthracis, and the bacterial toxin staphylococcal enterotoxin B (SEB). Using this system, we were able to detect SEB and inactivated Y. pestis individually as well as in two-plex assays at concentrations as low as 5 pg/mL and 10(6) CFU/mL, respectively. We also introduce super avidin-biotin system (SABS) as a viable and effective means to enhance assay signal responses and lower detection limits. Together these technologies represent substantial advances in point-of-care and point-of-use detection applications.
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Affiliation(s)
- Jason Wojciechowski
- Center for Bio, Molecular Science and Engineering, Bld. 30, US Naval Research Laboratory, 4555 Overlook Ave. SW, Washington DC 20376, USA; E-Mail:
| | - David Danley
- CombiMatrix Corporation, 6500 Harbour Heights Pkwy., Suite #303, Mukilteo, WA 98275, USA; E-Mails: (D.D.); (J.C.); (N.Y.)
| | - John Cooper
- CombiMatrix Corporation, 6500 Harbour Heights Pkwy., Suite #303, Mukilteo, WA 98275, USA; E-Mails: (D.D.); (J.C.); (N.Y.)
| | - Nina Yazvenko
- CombiMatrix Corporation, 6500 Harbour Heights Pkwy., Suite #303, Mukilteo, WA 98275, USA; E-Mails: (D.D.); (J.C.); (N.Y.)
| | - Chris Rowe Taitt
- Center for Bio, Molecular Science and Engineering, Bld. 30, US Naval Research Laboratory, 4555 Overlook Ave. SW, Washington DC 20376, USA; E-Mail:
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Pellett S, Tepp WH, Toth SI, Johnson EA. Comparison of the primary rat spinal cord cell (RSC) assay and the mouse bioassay for botulinum neurotoxin type A potency determination. J Pharmacol Toxicol Methods 2010; 61:304-10. [PMID: 20100585 DOI: 10.1016/j.vascn.2010.01.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/15/2010] [Accepted: 01/15/2010] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Botulinum neurotoxin (BoNT) type A is increasingly used in humans for pharmaceutical and cosmetic purposes. Currently, the standard assay used to determine potency of clinical samples, and the only assay approved by the FDA, is the in vivo mouse bioassay (MBA). However, due to several drawbacks of this assay (relatively large error, high cost, no standardization, requirement of high technical expertise, and use of large numbers of mice), there is an increasing need to replace this assay. A cell-based assay using primary rat spinal cord cells (RSC assay) has been previously reported to sensitively detect purified botulinum neurotoxin type A, and requires all biological properties of the toxin for detection. METHODS This study presents data on quantitative detection of potency of purified BoNT/A by a cell-based assay, using primary rat spinal cord cells (RSC assay). The sensitivity and error rate of the RSC assay was directly compared to the currently used mouse bioassay by repeated testing of the same purified BoNT/A sample by both assays. In addition, the potency of several samples of purified BoNT/A of unknown activity was determined in parallel by RSC assay and MBA. RESULTS The results indicate sensitivity of the RSC assay similar to the mouse bioassay, high reproducibility, and a lower error rate than the mouse bioassay. Direct comparison of potency determination of several purified BoNT/A samples by RSC assay and MBA resulted in very similar values, indicating very good correlation. DISCUSSION These data support the use of a cell-based assay for potency determination of purified BoNT/A as an alternative to the mouse bioassay.
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Affiliation(s)
- Sabine Pellett
- Department of Bacteriology, University of Wisconsin, Madison, Madison, WI 53706, USA
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Abstract
Sensitive and rapid detection of botulinum neurotoxins (BoNTs), the most poisonous substances known to date, is essential for studies of medical applications of BoNTs and detection of poisoned food, as well as for response to potential bioterrorist threats. Currently, the most common method of BoNT detection is the mouse bioassay. While this assay is sensitive, it is slow, quite expensive, has limited throughput and requires sacrificing animals. Herein, we discuss and compare recently developed alternative in vitro detection methods and assess their ability to supplement or replace the mouse bioassay in the analysis of complex matrix samples.
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Affiliation(s)
- Petr Čapek
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA;
| | - Tobin J. Dickerson
- Department of Chemistry and Worm Institute for Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
- Author to whom correspondence should be addressed; ; Tel.: +1-858-784-2522; Fax: +1-858-784-2590
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Čapek P, Dickerson TJ. Sensing the deadliest toxin: technologies for botulinum neurotoxin detection. Toxins (Basel) 2010; 2:24-53. [PMID: 22069545 PMCID: PMC3206617 DOI: 10.3390/toxins2020024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 12/17/2009] [Accepted: 12/22/2009] [Indexed: 11/16/2022] Open
Abstract
Sensitive and rapid detection of botulinum neurotoxins (BoNTs), the most poisonous substances known to date, is essential for studies of medical applications of BoNTs and detection of poisoned food, as well as for response to potential bioterrorist threats. Currently, the most common method of BoNT detection is the mouse bioassay. While this assay is sensitive, it is slow, quite expensive, has limited throughput and requires sacrificing animals. Herein, we discuss and compare recently developed alternative in vitro detection methods and assess their ability to supplement or replace the mouse bioassay in the analysis of complex matrix samples.
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Affiliation(s)
- Petr Čapek
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA;
| | - Tobin J. Dickerson
- Department of Chemistry and Worm Institute for Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Anderson GP, Liu JL, Hale ML, Bernstein RD, Moore M, Swain MD, Goldman ER. Development of antiricin single domain antibodies toward detection and therapeutic reagents. Anal Chem 2009; 80:9604-11. [PMID: 19072267 DOI: 10.1021/ac8019398] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single domain antibodies (sdAb) that bind ricin with high affinity and specificity were selected from a phage display library derived from the mRNA of heavy chain antibodies obtained from lymphocytes of immunized llamas. The sdAb were found to recognize three distinct epitopes on ricin. Representative sdAb were demonstrated to function as both capture and tracer elements in fluid array immunoassays, a limit of detection of 1.6 ng/mL was obtained. One sdAb pair in particular was found to be highly specific for ricin. While polyclonal antibodies cross react strongly with RCA120, the sdAb pair had minimal cross reactivity. In addition, the binders were found to be thermal stable, regaining their ricin binding activity following heating to 85 degrees C for an hour. Cycles of thermally induced unfolding of the sdAb and their subsequent refolding upon cooling was monitored by circular dichroism. As several of the sdAb were observed to bind to ricin's A chain, cell free translation assays were performed to monitor the ability of the sdAbs to inhibit ricin's biological activity. One of the sdAb (C8) was particularly effective and blocked ricin's biological activity with an effectiveness equal to that of a mouse antiricin antibody. These results indicate that antiricin sdAb have great potential for both diagnostic and therapeutic applications.
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Affiliation(s)
- George P Anderson
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
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Ozanich RM, Bruckner-Lea CJ, Warner MG, Miller K, Antolick KC, Marks JD, Lou J, Grate JW. Rapid multiplexed flow cytometric assay for botulinum neurotoxin detection using an automated fluidic microbead-trapping flow cell for enhanced sensitivity. Anal Chem 2009; 81:5783-93. [PMID: 19530657 DOI: 10.1021/ac9006914] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A bead-based sandwich immunoassay for botulinum neurotoxin serotype A (BoNT/A) has been developed and demonstrated using a recombinant 50 kDa fragment (BoNT/A-HC-fragment) of the BoNT/A heavy chain (BoNT/A-HC) as a structurally valid simulant. Three different anti-BoNT/A antibodies were attached to three different fluorescent dye encoded flow cytometry beads for multiplexing. The assay was conducted in two formats: a manual microcentrifuge tube format and an automated fluidic system format. Flow cytometry detection was used for both formats. The fluidic system used a novel microbead-trapping flow cell to capture antibody-coupled beads with subsequent sequential perfusion of sample, wash, dye-labeled reporter antibody, and final wash solutions. After the reaction period, the beads were collected for analysis by flow cytometry. Sandwich assays performed on the fluidic system gave median fluorescence intensity signals on the flow cytometer that were 2-4 times higher than assays performed manually in the same amount of time. Limits of detection were estimated at 1 pM (approximately 50 pg/mL for BoNT/A-HC-fragment) for the 15 min fluidic assay in buffer.
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Affiliation(s)
- Richard M Ozanich
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
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Yang M, Kostov Y, Bruck HA, Rasooly A. Gold nanoparticle-based enhanced chemiluminescence immunosensor for detection of Staphylococcal Enterotoxin B (SEB) in food. Int J Food Microbiol 2009; 133:265-71. [PMID: 19540011 DOI: 10.1016/j.ijfoodmicro.2009.05.029] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 05/26/2009] [Accepted: 05/27/2009] [Indexed: 10/20/2022]
Abstract
Staphylococcal enterotoxins (SEs) are major cause of foodborne diseases, so sensitive detection (<1 ng/ml) methods are needed for SE detection in food. The surface area, geometric and physical properties of gold nanoparticles make them well-suited for enhancing interactions with biological molecules in assays. To take advantage of the properties of gold nanoparticles for immunodetection, we have developed a gold nanoparticle-based enhanced chemiluminescence (ECL) immunosensor for detection of Staphylococcal Enterotoxin B (SEB) in food. Anti-SEB primary antibodies were immobilized onto a gold nanoparticle surface through physical adsorption and then the antibody-gold nanoparticle mixture was immobilized onto a polycarbonate surface. SEB was detected by a "sandwich-type" ELISA assay on the polycarbonate surface with a secondary antibody and ECL detection. The signal from ECL was read using a point-of-care detector based on a cooled charge-coupled device (CCD) sensor or a plate reader. The system was used to test for SEB in buffer and various foods (mushrooms, tomatoes, and baby food meat). The limit of detection was found to be approximately 0.01 ng/mL, which is approximately 10 times more sensitive than traditional ELISA. The gold nanoparticles were relatively easy to use for antibody immobilization because of their physical adsorption mechanism; no other reagents were required for immobilization. The use of our simple and inexpensive detector combined with the gold nanoparticle-based ECL method described here is adaptable to simplify and increase sensitivity of any immunological assay and for point-of-care diagnostics.
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Affiliation(s)
- Minghui Yang
- Center for Advanced Sensor Technology, University of Maryland Baltimore County, MD 21250, USA
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Wojciechowski JR, Shriver-Lake LC, Yamaguchi MY, Füreder E, Pieler R, Schamesberger M, Winder C, Prall HJ, Sonnleitner M, Ligler FS. Organic Photodiodes for Biosensor Miniaturization. Anal Chem 2009; 81:3455-61. [DOI: 10.1021/ac8027323] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jason R. Wojciechowski
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Lisa C. Shriver-Lake
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Mariko Y. Yamaguchi
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Erwin Füreder
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Roland Pieler
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Martin Schamesberger
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Christoph Winder
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Hans Jürgen Prall
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Max Sonnleitner
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
| | - Frances S. Ligler
- Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, and NanoIdent Technologies AG, Untere Donaulande 21-25, A-4020 Linz, Austria
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Sapsford KE, Francis J, Sun S, Kostov Y, Rasooly A. Miniaturized 96-well ELISA chips for staphylococcal enterotoxin B detection using portable colorimetric detector. Anal Bioanal Chem 2009; 394:499-505. [PMID: 19290511 DOI: 10.1007/s00216-009-2730-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 02/20/2009] [Accepted: 02/23/2009] [Indexed: 10/21/2022]
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Grate JW, Warner MG, Ozanich RM, Miller KD, Colburn HA, Dockendorff B, Antolick KC, Anheier NC, Lind MA, Lou J, Marks JD, Bruckner-Lea CJ. Renewable surface fluorescence sandwich immunoassay biosensor for rapid sensitive botulinum toxin detection in an automated fluidic format. Analyst 2009; 134:987-96. [PMID: 19381395 DOI: 10.1039/b900794f] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A renewable surface biosensor for rapid detection of botulinum neurotoxin serotype A is described based on fluidic automation of a fluorescence sandwich immunoassay, using a recombinant protein fragment of the toxin heavy chain ( approximately 50 kDa) as a structurally valid simulant. Monoclonal antibodies AR4 and RAZ1 bind to separate non-overlapping epitopes of the full botulinum holotoxin ( approximately 150 kDa). Both of the targeted epitopes are located on the recombinant fragment. The AR4 antibody was covalently bound to Sepharose beads and used as the capture antibody. A rotating rod flow cell was used to capture these beads delivered as a suspension by a sequential injection flow system, creating a 3.6 microL column. After perfusing the bead column with sample and washing away the matrix, the column was perfused with Alexa 647 dye-labeled RAZ1 antibody as the reporter. Optical fibers coupled to the rotating rod flow cell at a 90 degrees angle to one another delivered excitation light from a HeNe laser (633 nm) using one fiber and collected fluorescent emission light for detection with the other. After each measurement, the used Sepharose beads are released and replaced with fresh beads. In a rapid screening approach to sample analysis, the toxin simulant was detected to concentrations of 10 pM in less than 20 minutes using this system.
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Affiliation(s)
- Jay W Grate
- Pacific Northwest National Laboratory, P. O. Box 999, Richland, WA 99352, USA
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39
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Golden JP, Sapsford KE. Fluoroimmunoassays using the NRL array biosensor. Methods Mol Biol 2009; 503:273-292. [PMID: 19151947 DOI: 10.1007/978-1-60327-567-5_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Array-based biosensor technology offers the user the ability to detect and quantify multiple targets in multiple samples simultaneously (Analytical Sciences 23:5-10, 2007). The NRL Array Biosensor has been developed with the aim of creating a system for sensitive, rapid, on-site screening for multiple targets of interest. This system is fluorescence-based, using evanescent illumination of a waveguide, and has demonstrated the use of both sandwich and competitive immunoassays for the detection of both high and low molecular weight targets, respectively. The current portable, automated system has demonstrated detection of a wide variety of analytes ranging from simple chemical compounds to entire bacterial cells, with applications in food safety, disease diagnosis, homeland security and environmental monitoring.
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Affiliation(s)
- Joel P Golden
- Center for Bio/Molecular Science & Engineering, US Naval Research Laboratory, Washington, DC, USA
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40
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Kostov Y, Sergeev N, Wilson S, Herold KE, Rasooly A. A simple portable electroluminescence illumination-based CCD detector. Methods Mol Biol 2009; 503:259-72. [PMID: 19151946 DOI: 10.1007/978-1-60327-567-5_14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this chapter we describe a simple and relatively inexpensive Electroluminescence (EL) illumination and charged-coupled device (CCD) camera (EL-CCD) based detector for monitoring fluorescence and colorimetric assays. The portable battery-operated fluorescence detector includes an EL panel for fluoro-genic excitation at 490 nm, a cooled CCD digital camera to monitor emission at 523 nm, filters and a close up lens. The detector system is controlled by a laptop computer for camera operation, image acquisition and analysis. The system was tested using a fluorogenic peptide substrate (SNAP-25) for botulinum neurotoxin serotype A (BoNT-A) labeled with FITC. The level of detection of the system was found to be 1.25 nM of the peptide, similar to the detection level of a commercial photomultipler-based plate fluorometer. The multichannel EL-CCD was used with an assay plate capable of testing nine samples simultaneously in 1 min at this detection level. The portable system is small and is operated by a 12 V source. The modular detector was designed with easily interchangeable ELs, filters and lenses and can be used and adapted for a wide variety of fluorescence and colorimetric assays, fluorescence labels and assay formats.
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Affiliation(s)
- Yordan Kostov
- Center for Advanced Sensor Technology, University of Maryland Baltimore County, Baltimore, MD, USA
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41
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Shriver-Lake LC, Charles PT, Taitt CR. Immobilization of biomolecules onto silica and silica-based surfaces for use in planar array biosensors. Methods Mol Biol 2009; 504:419-440. [PMID: 19159109 DOI: 10.1007/978-1-60327-569-9_23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Several methods are described in which a biological recognition molecule--a critical element in any biosensor--is immobilized onto a silica or silica-based sensing substrate. Although several variations are described, the methods for covalent immobilization share a common theme and are generally composed of three steps: modification of the surface to add specific functional groups (using appropriate silanes or an amine or carboxyl-containing hydrogel), covalent attachment of a crosslinker through one of its reactive moieties, and finally, covalent linking of the biomolecule (recognition element) to the remaining reactive moiety of the crosslinker. One final method is presented in which the surface is modified with a highly hydrophobic silane and a glycolipid recognition element immobilized, essentially irreversibly, by hydrophobic interactions. All of the methods described have been successfully used to immobilize biological recognition molecules onto sensing surfaces, with full functionality in biosensor-binding assays.
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Affiliation(s)
- Lisa C Shriver-Lake
- Center for Bio/Molecular Science & Engineering, US Naval Research Laboratory, Washington, DC, USA
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Labib M, Hedström M, Amin M, Mattiasson B. A capacitive biosensor for detection of staphylococcal enterotoxin B. Anal Bioanal Chem 2008; 393:1539-44. [DOI: 10.1007/s00216-008-2559-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 11/06/2008] [Accepted: 12/01/2008] [Indexed: 10/21/2022]
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Taitt CR, Shriver-Lake LC, Ngundi MM, Ligler FS. Array Biosensor for Toxin Detection: Continued Advances. SENSORS 2008; 8:8361-8377. [PMID: 27873991 PMCID: PMC3791022 DOI: 10.3390/s8128361] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 11/26/2008] [Accepted: 12/09/2008] [Indexed: 11/17/2022]
Abstract
The following review focuses on progress made in the last five years with the NRL Array Biosensor, a portable instrument for rapid and simultaneous detection of multiple targets. Since 2003, the Array Biosensor has been automated and miniaturized for operation at the point-of-use. The Array Biosensor has also been used to demonstrate (1) quantitative immunoassays against an expanded number of toxins and toxin indicators in food and clinical fluids, and (2) the efficacy of semi-selective molecules as alternative recognition moieties. Blind trials, with unknown samples in a variety of matrices, have demonstrated the versatility, sensitivity, and reliability of the automated system.
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Affiliation(s)
- Chris Rowe Taitt
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Code 6900, Washington, DC 20375-5348, USA.
| | - Lisa C Shriver-Lake
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Code 6900, Washington, DC 20375-5348, USA.
| | - Miriam M Ngundi
- Food and Drug Administration, N29 RM418 HFM-434, 8800 Rockville Pike, Bethesda, MD 20892, USA.
| | - Frances S Ligler
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Code 6900, Washington, DC 20375-5348, USA.
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Yang M, Kostov Y, Bruck HA, Rasooly A. Carbon nanotubes with enhanced chemiluminescence immunoassay for CCD-based detection of Staphylococcal enterotoxin B in food. Anal Chem 2008; 80:8532-7. [PMID: 18855418 PMCID: PMC2845180 DOI: 10.1021/ac801418n] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enhanced chemiluminescence (ECL) detection can significantly enhance the sensitivity of immunoassays but often requires expensive and complex detectors. The need for these detectors limits broader use of ECL in immunoassay applications. To make ECL more practical for immunoassays, we utilize a simple cooled charge-coupled device (CCD) detector combined with carbon nanotubes (CNTs) for primary antibody immobilization to develop a simple and portable point-of-care immunosensor. This combination of ECL, CNT, and CCD detector technologies is used to improve the detection of Staphylococcal enterotoxin B (SEB) in food. Anti-SEB primary antibodies were immobilized onto the CNT surface, and the antibody-nanotube mixture was immobilized onto a polycarbonate surface. SEB was then detected by an ELISA assay on the CNT-polycarbonate surface with an ECL assay. SEB in buffer, soy milk, apple juice, and meat baby food was assayed with a LOD of 0.01 ng/mL using our CCD detector, a level similar to the detection limit obtained with a fluorometric detector when using the CNTs. This level is far more sensitive than the conventional ELISA, which has a LOD of approximately 1 ng/mL. Our simple, versatile, and inexpensive point-of-care immunosensor combined with the CNT-ECL immunoassay method described in this work can also be used to simplify and increase sensitivity for many other types of diagnostics and detection assays.
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Affiliation(s)
| | | | | | - Avraham Rasooly
- To whom correspondence should be addressed. Mail: NIH/NCI, 6130 Executive Blvd. EPN, Room 6035A, Rockville, MD 20852. Phone: (301) 402-4185. Fax: (301) 402-7819.
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Seidel M, Niessner R. Automated analytical microarrays: a critical review. Anal Bioanal Chem 2008; 391:1521-44. [PMID: 18504563 PMCID: PMC7080066 DOI: 10.1007/s00216-008-2039-3] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 02/25/2008] [Accepted: 02/28/2008] [Indexed: 11/24/2022]
Abstract
Microarrays provide a powerful analytical tool for the simultaneous detection of multiple analytes in a single experiment. The specific affinity reaction of nucleic acids (hybridization) and antibodies towards antigens is the most common bioanalytical method for generating multiplexed quantitative results. Nucleic acid-based analysis is restricted to the detection of cells and viruses. Antibodies are more universal biomolecular receptors that selectively bind small molecules such as pesticides, small toxins, and pharmaceuticals and to biopolymers (e.g. toxins, allergens) and complex biological structures like bacterial cells and viruses. By producing an appropriate antibody, the corresponding antigenic analyte can be detected on a multiplexed immunoanalytical microarray. Food and water analysis along with clinical diagnostics constitute potential application fields for multiplexed analysis. Diverse fluorescence, chemiluminescence, electrochemical, and label-free microarray readout systems have been developed in the last decade. Some of them are constructed as flow-through microarrays by combination with a fluidic system. Microarrays have the potential to become widely accepted as a system for analytical applications, provided that robust and validated results on fully automated platforms are successfully generated. This review gives an overview of the current research on microarrays with the focus on automated systems and quantitative multiplexed applications.
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Affiliation(s)
- Michael Seidel
- Chair for Analytical Chemistry and Institute of Hydrochemistry, Technische Universität München, Marchioninistrasse 17, 81377, München, Germany.
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A fluorescence detection platform using spatial electroluminescent excitation for measuring botulinum neurotoxin A activity. Biosens Bioelectron 2008; 24:618-25. [PMID: 18644709 DOI: 10.1016/j.bios.2008.06.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 04/23/2008] [Accepted: 06/04/2008] [Indexed: 11/22/2022]
Abstract
Current biodetection illumination technologies (laser, LED, tungsten lamp, etc.) are based on spot illumination with additional optics required when spatial excitation is required. Herein we describe a new approach of spatial illumination based on electroluminescence (EL) semiconductor strips available in several wavelengths, greatly simplifying the biosensor design by eliminating the need for additional optics. This work combines EL excitation with charge-coupled device (CCD) based detection (EL-CCD detector) of fluorescence for developing a simple portable detector for botulinum neurotoxin A (BoTN-A) activity analysis. A Förster Resonance Energy Transfer (FRET) activity assay for BoTN-A was used to both characterize and optimize the EL-CCD detector. The system consists of two modules: (1) the detection module which houses the CCD camera and emission filters, and (2) the excitation and sample module, containing the EL strip, the excitation filter and the 9-well sample chip. The FRET activity assay used in this study utilized a FITC/DABCYL-SNAP-25 peptide substrate in which cleavage of the substrate by BoTN-A, or its light chain derivative (LcA), produced an increase in fluorescence emission. EL-CCD detector measured limits of detection (LODs) were similar to those measured using a standard fluorescent plate reader with valves between 0.625 and 1.25 nM (31-62 ng/ml) for LcA and 0.313 nM (45 ng/ml) for the full toxin, BoTN-A. As far as the authors are aware this is the first demonstration of phosphor-based EL strips being used for the spatial illumination/excitation of a surface, coupled with CCD for point of care detection.
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Soto CM, Martin BD, Sapsford KE, Blum AS, Ratna BR. Toward single molecule detection of staphylococcal enterotoxin B: mobile sandwich immunoassay on gliding microtubules. Anal Chem 2008; 80:5433-40. [PMID: 18543949 DOI: 10.1021/ac800541x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An immunoassay based on gliding microtubules (MTs) is described for the detection of staphylococcal enterotoxin B. Detection is performed in a sandwich immunoassay format. Gliding microtubules carry the antigen-specific "capture" antibody, and bound analyte is detected using a fluorescent viral scaffold as the tracer. A detailed modification scheme for the MTs postpolymerization is described along with corresponding quantification by fluorescence spectroscopy. The resultant antibody-MTs maintain their morphology and gliding capabilities. We report a limit of detection down to 0.5 ng/mL during active transport in a 30 min assay time and down to 1 ng/mL on static surfaces. This study demonstrates the kinesin/MT-mediated capture, transport, and detection of the biowarfare agent SEB in a microfluidic format.
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Affiliation(s)
- Carissa M Soto
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA.
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49
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Detection of Staphylococcus enterotoxin B using fluorescent immunoliposomes as label for immunochromatographic testing. Anal Biochem 2008; 377:182-8. [DOI: 10.1016/j.ab.2008.02.032] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 02/27/2008] [Accepted: 02/28/2008] [Indexed: 11/21/2022]
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50
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