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Carrasco-Acosta M, Garcia-Jimenez P. Development of Multiplex RT qPCR Assays for Simultaneous Detection and Quantification of Faecal Indicator Bacteria in Bathing Recreational Waters. Microorganisms 2024; 12:1223. [PMID: 38930605 PMCID: PMC11205496 DOI: 10.3390/microorganisms12061223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 06/05/2024] [Accepted: 06/14/2024] [Indexed: 06/28/2024] Open
Abstract
In this study, we designed and validated in silico and experimentally a rapid, sensitive, and specific multiplex RT qPCR for the detection and quantification of faecal indicator bacteria (FIB) used as microbiological references in marine bathing water regulations (Escherichia coli and intestinal enterococci). The 16S rRNA gene was used to quantify group-specific enterococci and Escherichia/Shigella and species-specific such as Enterococcus faecalis and E. faecium. Additionally, a ybbW gene encoding allantoin transporter protein was used to detect E. coli. An assessment of marine coastal systems (i.e., marine water and sediment) revealed that intestinal enterococci were the predominant group compared to Escherichia/Shigella. The low contribution of E. faecalis to the intestinal enterococci group was reported. As E. faecalis and E. faecium were reported at low concentrations, it is assumed that other enterococci of faecal origin are contributing to the high gene copy number of this group-specific enterococci. Moreover, low 16S rRNA gene copy numbers with respect to E. faecalis and E. faecium were reported in seawater compared to marine sediment. We conclude that marine sediments can affect the quantification of FIBs included in bathing water regulations. Valuing the quality of the marine coastal system through sediment monitoring is recommended.
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Affiliation(s)
| | - Pilar Garcia-Jimenez
- Department of Biology, Faculty of Marine Sciences, Instituto Universitario de Investigación en Estudios Ambientales y Recursos Naturales i-UNAT, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain;
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Lim J, Zhou S, Baek J, Kim AY, Valera E, Sweedler J, Bashir R. A Blood Drying Process for DNA Amplification. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2307959. [PMID: 37888793 DOI: 10.1002/smll.202307959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Indexed: 10/28/2023]
Abstract
The presence of numerous inhibitors in blood makes their use in nucleic acid amplification techniques difficult. Current methods for extracting and purifying pathogenic DNA from blood involve removal of inhibitors, resulting in low and inconsistent DNA recovery rates. To address this issue, a biphasic method is developed that simultaneously achieves inhibitor inactivation and DNA amplification without the need for a purification step. Inhibitors are physically trapped in the solid-phase dried blood matrix by blood drying, while amplification reagents can move into the solid nano-porous dried blood and initiate the amplification. It is demonstrated that the biphasic method has significant improvement in detection limits for bacteria such as Escherichia coli, Methicillin-resistant Staphylococcus aureus, Methicillin-Sensitive Staphylococcus aureus using loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA). Several factors, such as drying time, sample volume, and material properties are characterized to increase sensitivity and expand the application of the biphasic assay to blood diagnostics. With further automation, this biphasic technique has the potential to be used as a diagnostic platform for the detection of pathogens eliminating lengthy culture steps.
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Affiliation(s)
- Jongwon Lim
- Nick Holonyak Jr. Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Shuaizhen Zhou
- Department of Energy Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Janice Baek
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Alicia Yeaeun Kim
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Enrique Valera
- Nick Holonyak Jr. Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jonathan Sweedler
- Department of Energy Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Rashid Bashir
- Nick Holonyak Jr. Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Biomedical and Translational Science, Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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Li J, Shang MY, Deng SL, Li M, Su N, Ren XD, Sun XG, Li WM, Li YW, Li RX, Huang Q, Lu WP. Development of a novel integrated isothermal amplification system for detection of bacteria-spiked blood samples. AMB Express 2023; 13:135. [PMID: 38019349 PMCID: PMC10686969 DOI: 10.1186/s13568-023-01643-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 11/19/2023] [Indexed: 11/30/2023] Open
Abstract
Bloodstream infection (BSI) caused by bacteria is highly pathogenic and lethal, and easily develops whole-body inflammatory state. Immediate identification of disease-causing bacteria can improve patient prognosis. Traditional testing methods are not only time-consuming, but such tests are limited to laboratories. Recombinase polymerase amplification combined with lateral flow dipstick (RPA-LFD) holds great promise for rapid nucleic acid detection, but the uncapping operation after amplification easily contaminates laboratories. Therefore, the establishment of a more effective integrated isothermal amplification system has become an urgent problem to be solved. In this study, we designed and fabricated a hermetically sealed integrated isothermal amplification system. Combining with this system, a set of RPA-LFD assays for detecting S. aureus, K. peneumoniae, P. aeruginosa, and H. influenza in BSI were established and evaluated. The whole process could be completed in less than 15 min and the results can be visualized by the naked eye. The developed RPA-LFD assays displayed a good sensitivity, and no cross-reactivity was observed in seven similar bacterial genera. The results obtained with 60 clinical samples indicated that the developed RPA-LFD assays had high specifcity and sensitivity for identifying S. aureus, K. peneumoniae, P. aeruginosa, and H. influenza in BSI. In conclusion, our results showed that the developed RPA-LFD assay is an alternative to existing PCR-based methods for detection of S. aureus, K. peneumoniae, P. aeruginosa, and H. influenza in BSI in primary hospitals.
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Affiliation(s)
- Jin Li
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Mei-Yun Shang
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Shao-Li Deng
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Min Li
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Ning Su
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Xiao-Dong Ren
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Xian-Ge Sun
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Wen-Man Li
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Yu-Wei Li
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Ruo-Xu Li
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China
| | - Qing Huang
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China.
| | - Wei-Ping Lu
- Department of Laboratory Medicine, Daping Hospital, Army Medical University (Third Military Medical University), Chongqing, 400042, P.R. China.
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Xesfyngi Y, Georgoutsou-Spyridonos M, Tripathy A, Milionis A, Poulikakos D, Mastellos DC, Tserepi A. A High-Performance Antibacterial Nanostructured ZnO Microfluidic Device for Controlled Bacterial Lysis and DNA Release. Antibiotics (Basel) 2023; 12:1276. [PMID: 37627695 PMCID: PMC10451374 DOI: 10.3390/antibiotics12081276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 08/27/2023] Open
Abstract
In this work, the antibacterial properties of nanostructured zinc oxide (ZnO) surfaces are explored by incorporating them as walls in a simple-to-fabricate microchannel device. Bacterial cell lysis is demonstrated and quantified in such a device, which functions due to the action of its nanostructured ZnO surfaces in contact with the working fluid. To shed light on the mechanism responsible for lysis, E. coli bacteria were incubated in zinc and nanostructured ZnO substrates, as well as the here-investigated ZnO-based microfluidic devices. The unprecedented killing efficiency of E. coli in nanostructured ZnO microchannels, effective after a 15 min incubation, paves the way for the implementation of such microfluidic chips in the disinfection of bacteria-containing solutions. In addition, the DNA release was confirmed by off-chip PCR and UV absorption measurements. The results indicate that the present nanostructured ZnO-based microfluidic chip can, under light, achieve partial inactivation of the released bacterial DNA via reactive oxygen species-mediated oxidative damage. The present device concept can find broader applications in cases where the presence of DNA in a sample is not desirable. Furthermore, the present microchannel device enables, in the dark, efficient release of bacterial DNA for downstream genomic DNA analysis. The demonstrated potential of this antibacterial device for tailored dual functionality in light/dark conditions is the main novel contribution of the present work.
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Affiliation(s)
- Yvonni Xesfyngi
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research (NCSR) “Demokritos”, Patr. Gregoriou E’ and 27 Neapoleos Str., 15341 Aghia Paraskevi, Greece; (Y.X.); (M.G.-S.)
| | - Maria Georgoutsou-Spyridonos
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research (NCSR) “Demokritos”, Patr. Gregoriou E’ and 27 Neapoleos Str., 15341 Aghia Paraskevi, Greece; (Y.X.); (M.G.-S.)
| | - Abinash Tripathy
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; (A.T.); (A.M.); (D.P.)
| | - Athanasios Milionis
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; (A.T.); (A.M.); (D.P.)
| | - Dimos Poulikakos
- Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; (A.T.); (A.M.); (D.P.)
| | - Dimitrios C. Mastellos
- Institute of Nuclear & Radiological Sciences and Technology, Energy & Safety, National Center for Scientific Research (NCSR) “Demokritos”, Patr. Gregoriou E’ and 27 Neapoleos Str., 15341 Aghia Paraskevi, Greece;
| | - Angeliki Tserepi
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research (NCSR) “Demokritos”, Patr. Gregoriou E’ and 27 Neapoleos Str., 15341 Aghia Paraskevi, Greece; (Y.X.); (M.G.-S.)
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Bienes KM, Mao L, Selekon B, Gonofio E, Nakoune E, Wong G, Berthet N. Rapid Detection of the Varicella-Zoster Virus Using a Recombinase-Aided Amplification-Lateral Flow System. Diagnostics (Basel) 2022; 12:diagnostics12122957. [PMID: 36552964 PMCID: PMC9777233 DOI: 10.3390/diagnostics12122957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/05/2022] [Accepted: 11/14/2022] [Indexed: 11/29/2022] Open
Abstract
Varicella-zoster virus (VZV) is the etiological agent of varicella (chickenpox) and herpes zoster (shingles). VZV infections are ubiquitous and highly contagious, and diagnosis is mostly based on the assessment of signs and symptoms. However, monkeypox, an emerging infectious disease caused by the monkeypox virus (MPXV), has clinical manifestations that are similar to those of VZV infections. With the recent monkeypox outbreak in non-endemic regions, VZV infections are likely to be misdiagnosed in the absence of laboratory testing. Considering the lack of accessible diagnostic tests that discriminate VZV from MPXV or other poxviruses, a handy and affordable detection system for VZV is crucial for rapid differential diagnosis. Here, we developed a new detection method for VZV using recombinase-aided amplification technology, combined with the lateral flow system (RAA-LF). Given the prevalence of VZV worldwide, this method can be applied not only to distinguish VZV from other viruses causing rash, but also to foster early detection, contributing substantially to disease control.
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Affiliation(s)
- Kathrina Mae Bienes
- Unit of Discovery and Molecular Characterization of Pathogens, Center for Microbes, Development and Health, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Lingjing Mao
- Unit of Discovery and Molecular Characterization of Pathogens, Center for Microbes, Development and Health, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | | | - Ella Gonofio
- Institut Pasteur of Bangui, Bangui, Central African Republic
| | | | - Gary Wong
- Viral Hemorrhagic Fevers Research Unit, CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
- Correspondence: (G.W.); (N.B.)
| | - Nicolas Berthet
- Unit of Discovery and Molecular Characterization of Pathogens, Center for Microbes, Development and Health, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
- Cellule d’Intervention Biologique d’Urgence, Unité Environnement et Risque Infectieux, Institut Pasteur, 75724 Paris, France
- Correspondence: (G.W.); (N.B.)
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Srisrattakarn A, Panpru P, Tippayawat P, Chanawong A, Tavichakorntrakool R, Daduang J, Wonglakorn L, Lulitanond A. Rapid detection of methicillin-resistant Staphylococcus aureus in positive blood-cultures by recombinase polymerase amplification combined with lateral flow strip. PLoS One 2022; 17:e0270686. [PMID: 35771885 PMCID: PMC9246191 DOI: 10.1371/journal.pone.0270686] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 06/15/2022] [Indexed: 12/26/2022] Open
Abstract
Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), is an important bacterium that causes community and healthcare-related infections throughout the world. However, the current conventional detection methods are time-consuming. We therefore developed and evaluated a recombinase polymerase amplification-lateral flow strip (RPA-LF) approach for detection of MRSA in positive blood-culture samples. Sixty positive blood-cultures from a hospital were tested directly without DNA extraction and purification before the amplification reaction. RPA primers and probes were designed for nuc (encoding thermonuclease) and mecA (encoding penicillin-binding protein 2a) genes to diagnose S. aureus and its methicillin-resistance status. The RPA reaction occurred under isothermal conditions (45°C) within 20 min and a result was provided by the LF strip in a further 5 min at room temperature. The evaluation of RPA-LF using blood-culture samples showed 93.3% (14/15) sensitivity for identifying S. aureus, and no cross-amplification was seen [100% (45/45) specificity]. For detection of methicillin resistance, the RPA-LF test provided 100% (16/16) sensitivity and 97.7% (43/44) specificity. The RPA-LF is rapid, highly sensitive, robust and easy to use. It can be used for direct detection of MRSA with no requirement for special equipment.
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Affiliation(s)
- Arpasiri Srisrattakarn
- Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Pimchanok Panpru
- Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Patcharaporn Tippayawat
- Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Department of Medical Technology, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Aroonwadee Chanawong
- Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Department of Medical Technology, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Ratree Tavichakorntrakool
- Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Department of Medical Technology, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Jureerut Daduang
- Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Department of Medical Technology, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Lumyai Wonglakorn
- Clinical Microbiology Unit, Srinagarind Hospital, Khon Kaen University, Khon Kaen, Thailand
| | - Aroonlug Lulitanond
- Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Department of Medical Technology, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
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Recombinase Polymerase Amplification Combined with Real-Time Fluorescent Probe for Mycoplasma pneumoniae Detection. J Clin Med 2022; 11:jcm11071780. [PMID: 35407388 PMCID: PMC9000086 DOI: 10.3390/jcm11071780] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 02/04/2023] Open
Abstract
Mycoplasma pneumoniae (M. pneumoniae) is one of the major causes of community-acquired pneumonia, accounting for 20-40% of total cases. Rapid and accurate detection of M. pneumoniae is crucial for the diagnosis and rational selection of antibiotics. In this study, we set up a real-time recombinase polymerase amplification (RPA) assay to detect the conserved gene CARDS of M. pneumoniae. The amplification can be finished in 20 min at a wide temperature range from 37-41 °C. The limit of detection of RPA assay was 10 fg per microliter. Cross-reaction with commonly detected respiratory pathogens was not observed using RPA assay. Among clinical sputum samples, the detection rate of RPA assay and real-time PCR assay was 48.4% (92/190) and 46.3% (88/190), respectively (p = 0.68). Therefore, the RPA assay for M. pneumoniae detection is rapid and easy to use and may serve as a promising test for early diagnosis of M. pneumoniae infection.
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Isothermal Recombinase Polymerase Amplification (RPA) of E. coli gDNA in Commercially Fabricated PCB-Based Microfluidic Platforms. MICROMACHINES 2021; 12:mi12111387. [PMID: 34832799 PMCID: PMC8619769 DOI: 10.3390/mi12111387] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 11/04/2021] [Accepted: 11/10/2021] [Indexed: 12/04/2022]
Abstract
Printed circuit board (PCB) technology has been recently proposed as a convenient platform for seamlessly integrating electronics and microfluidics in the same substrate, thus facilitating the introduction of integrated and low-cost microfluidic devices to the market, thanks to the inherent upscaling potential of the PCB industry. Herein, a microfluidic chip, encompassing on PCB both a meandering microchannel and microheaters to accommodate recombinase polymerase amplification (RPA), is designed and commercially fabricated for the first time on PCB. The developed microchip is validated for RPA-based amplification of two E. coli target genes compared to a conventional thermocycler. The RPA performance of the PCB microchip was found to be well-comparable to that of a thermocycler yet with a remarkably lower power consumption (0.6 W). This microchip is intended for seamless integration with biosensors in the same PCB substrate for the development of a point-of-care (POC) molecular diagnostics platform.
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Cai Q, Wang R, Qiao Z, Yang W. Single-digit Salmonella detection with the naked eye using bio-barcode immunoassay coupled with recombinase polymerase amplification and a CRISPR-Cas12a system. Analyst 2021; 146:5271-5279. [PMID: 34355716 DOI: 10.1039/d1an00717c] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The ability to visually detect low numbers of Salmonella in food samples is highly valuable but remains a challenge. Here we present a novel platform for ultrasensitive and visual detection of Salmonella Typhimurium by integrating the bio-barcode immunoassay (BCA), recombinase polymerase amplification (RPA), and CRISPR-Cas12a cleavage in a single reaction system (termed as BCA-RPA-Cas12a). In the system, the target bacteria were separated by immunomagnetic nanoparticles and labeled with numerous barcode AuNPs, which carry abundant bio-barcode DNA molecules to amplify the signal. Afterwards, the bio-barcode DNA molecules were amplified by RPA and subsequently triggered the cleavage activity of Cas12a to generate the fluorescence signal. Due to this triplex signal amplification, the BCA-RPA-Cas12a system can selectively detect Salmonella Typhimurium at the single-digit level with the naked eye under blue light within 60 min. Meanwhile, this novel platform was successfully applied to detect Salmonella Typhimurium in spiked milk samples with a similar sensitivity and satisfactory recovery, indicating its potential application in real samples. Furthermore, in virtue of the versatility of the antibody in the stage of BCA, the BCA-RPA-Cas12a system can be extended to further application in other bacteria detection and food safety monitoring.
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Affiliation(s)
- Qiqi Cai
- College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China.
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