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Xu S, Lee I, Kwon SJ, Kim E, Nevo L, Straight L, Murata H, Matyjaszewski K, Dordick JS. Split fluorescent protein-mediated multimerization of cell wall binding domain for highly sensitive and selective bacterial detection. N Biotechnol 2024; 82:54-64. [PMID: 38750815 DOI: 10.1016/j.nbt.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 04/22/2024] [Accepted: 05/08/2024] [Indexed: 05/18/2024]
Abstract
Cell wall peptidoglycan binding domains (CBDs) of cell lytic enzymes, including bacteriocins, autolysins and bacteriophage endolysins, enable highly selective bacterial binding, and thus, have potential as biorecognition molecules for nondestructive bacterial detection. Here, a novel design for a self-complementing split fluorescent protein (FP) complex is proposed, where a multimeric FP chain fused with specific CBDs ((FP-CBD)n) is assembled inside the cell, to improve sensitivity by enhancing the signal generated upon Staphylococcus aureus or Bacillus anthracis binding. Flow cytometry shows enhanced fluorescence on the cell surface with increasing FP stoichiometry and surface plasmon resonance reveals nanomolar binding affinity to isolated peptidoglycan. The breadth of function of these complexes is demonstrated through the use of CBD modularity and the ability to attach enzymatic detection modalities. Horseradish peroxidase-coupled (FP-CBD)n complexes generate a catalytic amplification, with the degree of amplification increasing as a function of FP length, reaching a limit of detection (LOD) of 103 cells/droplet (approximately 0.1 ng S. aureus or B. anthracis) within 15 min on a polystyrene surface. These fusion proteins can be multiplexed for simultaneous detection. Multimeric split FP-CBD fusions enable use as a biorecognition molecule with enhanced signal for use in bacterial biosensing platforms.
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Affiliation(s)
- Shirley Xu
- Department of Chemical and Biological Engineering, and Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA
| | - Inseon Lee
- Department of Chemical and Biological Engineering, and Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA
| | - Seok-Joon Kwon
- Department of Chemical and Biological Engineering, and Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA
| | - Eunsol Kim
- Department of Chemical and Biological Engineering, and Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA
| | - Liv Nevo
- Department of Chemical and Biological Engineering, and Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA
| | - Lorelli Straight
- Department of Biology, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA
| | - Hironobu Murata
- Department of Chemistry, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA, USA
| | | | - Jonathan S Dordick
- Department of Chemical and Biological Engineering, and Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA; Department of Biology, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY, USA.
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2
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Lu H, Ni SQ. Review on sterilization techniques, and the application potential of phage lyase and lyase immobilization in fighting drug-resistant bacteria. J Mater Chem B 2024; 12:3317-3335. [PMID: 38380677 DOI: 10.1039/d3tb02366d] [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: 02/22/2024]
Abstract
Many human health problems and property losses caused by pathogenic contamination cannot be underestimated. Bactericidal techniques have been extensively studied to address this issue of public health and economy. Bacterial resistance develops as a result of the extensive use of single or multiple but persistent usage of sterilizing drugs, and the emergence of super-resistant bacteria brings new challenges. Therefore, it is crucial to control pathogen contamination by applying innovative and effective sterilization techniques. As organisms that exist in nature and can specifically kill bacteria, phages have become the focus as an alternative to antibacterial agents. Furthermore, phage-encoded lyases are proteins that play important roles in phage sterilization. The in vitro sterilization of phage lyase has been developed as a novel biosterilization technique to reduce bacterial resistance and is more environmentally friendly than conventional sterilization treatments. For the shortcomings of enzyme applications, this review discusses the enzyme immobilization methods and the application potential of immobilized lyases for sterilization. Although some techniques provide effective solutions, immobilized lyase sterilization technology has been proven to be a more effective innovation for efficient pathogen killing and reducing bacterial resistance. We hope that this review can provide new insights for the development of sterilization techniques.
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Affiliation(s)
- Han Lu
- School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China.
| | - Shou-Qing Ni
- School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China.
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3
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Zha J, Li J, Su Z, Akimbekov N, Wu X. Lysostaphin: Engineering and Potentiation toward Better Applications. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:11441-11457. [PMID: 36082619 DOI: 10.1021/acs.jafc.2c03459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Lysostaphin is a potent bacteriolytic enzyme with endopeptidase activity against the common pathogen Staphylococcus aureus. By digesting the pentaglycine crossbridge in the cell wall peptidoglycan of S. aureus including the methicillin-resistant strains, lysostaphin initiates rapid lysis of planktonic and sessile cells (biofilms) and has great potential for use in agriculture, food industries, and pharmaceutical industries. In the past few decades, there have been tremendous efforts in potentiating lysostaphin for better applications in these fields, including engineering of the enzyme for higher potency and lower immunogenicity with longer-lasting effects, formulation and immobilization of the enzyme for higher stability and better durability, and recombinant expression for low-cost industrial production and in situ biocontrol. These achievements are extensively reviewed in this article focusing on applications in disease control, food preservation, surface decontamination, and pathogen detection. In addition, some basic properties of lysostaphin that have been controversial and only elucidated recently are summarized, including the substrate-binding properties, the number of zinc-binding sites, the substrate range, and the cleavage site in the pentaglycine crossbridge. Resistance to lysostaphin is also highlighted with a focus on various mechanisms. This article is concluded with a discussion on the limitations and future perspectives for the actual applications of lysostaphin.
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Affiliation(s)
- Jian Zha
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Jingyuan Li
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Zheng Su
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Nuraly Akimbekov
- Department of Biotechnology, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan
| | - Xia Wu
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
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4
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Costa SP, Nogueira CL, Cunha AP, Lisac A, Carvalho CM. Potential of bacteriophage proteins as recognition molecules for pathogen detection. Crit Rev Biotechnol 2022:1-18. [PMID: 35848817 DOI: 10.1080/07388551.2022.2071671] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Bacterial pathogens are leading causes of infections with high mortality worldwide having a great impact on healthcare systems and the food industry. Gold standard methods for bacterial detection mainly rely on culture-based technologies and biochemical tests which are laborious and time-consuming. Regardless of several developments in existing methods, the goal of achieving high sensitivity and specificity, as well as a low detection limit, remains unaccomplished. In past years, various biorecognition elements, such as antibodies, enzymes, aptamers, or nucleic acids, have been widely used, being crucial for the pathogens detection in different complex matrices. However, these molecules are usually associated with high detection limits, demand laborious and costly production, and usually present cross-reactivity. (Bacterio)phage-encoded proteins, especially the receptor binding proteins (RBPs) and cell-wall binding domains (CBDs) of endolysins, are responsible for the phage binding to the bacterial surface receptors in different stages of the phage lytic cycle. Due to their remarkable properties, such as high specificity, sensitivity, stability, and ability to be easily engineered, they are appointed as excellent candidates to replace conventional recognition molecules, thereby contributing to the improvement of the detection methods. Moreover, they offer several possibilities of application in a variety of detection systems, such as magnetic, optical, and electrochemical. Herein we provide a review of phage-derived bacterial binding proteins, namely the RBPs and CBDs, with the prospect to be employed as recognition elements for bacteria. Moreover, we summarize and discuss the various existing methods based on these proteins for the detection of nosocomial and foodborne pathogens.
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Affiliation(s)
- Susana P Costa
- Centre of Biological Engineering, University of Minho, Braga, Portugal.,International Iberian Nanotechnology Laboratory, Braga, Portugal.,Instituto de Engenharia de Sistemas e Computadores-Microsistemas e Nanotecnologias (INESC MN), IN-Institute of Nanoscience and Nanotechnolnology, Lisbon, Portugal
| | - Catarina L Nogueira
- International Iberian Nanotechnology Laboratory, Braga, Portugal.,Instituto de Engenharia de Sistemas e Computadores-Microsistemas e Nanotecnologias (INESC MN), IN-Institute of Nanoscience and Nanotechnolnology, Lisbon, Portugal
| | - Alexandra P Cunha
- Centre of Biological Engineering, University of Minho, Braga, Portugal.,International Iberian Nanotechnology Laboratory, Braga, Portugal
| | - Ana Lisac
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
| | - Carla M Carvalho
- International Iberian Nanotechnology Laboratory, Braga, Portugal
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5
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Rahman MU, Wang W, Sun Q, Shah JA, Li C, Sun Y, Li Y, Zhang B, Chen W, Wang S. Endolysin, a Promising Solution against Antimicrobial Resistance. Antibiotics (Basel) 2021; 10:1277. [PMID: 34827215 PMCID: PMC8614784 DOI: 10.3390/antibiotics10111277] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/14/2021] [Accepted: 10/16/2021] [Indexed: 12/24/2022] Open
Abstract
Antimicrobial resistance (AMR) is a global crisis for human public health which threatens the effective prevention and control of ever-increasing infectious diseases. The advent of pandrug-resistant bacteria makes most, if not all, available antibiotics invalid. Meanwhile, the pipeline of novel antibiotics development stagnates, which prompts scientists and pharmacists to develop unconventional antimicrobials. Bacteriophage-derived endolysins are cell wall hydrolases which could hydrolyze the peptidoglycan layer from within and outside of bacterial pathogens. With high specificity, rapid action, high efficiency, and low risk of resistance development, endolysins are believed to be among the best alternative therapeutic agents to treat multidrug resistant (MDR) bacteria. As of now, endolysins have been applied to diverse aspects. In this review, we comprehensively introduce the structures and activities of endolysins and summarize the latest application progress of recombinant endolysins in the fields of medical treatment, pathogen diagnosis, food safety, and agriculture.
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Affiliation(s)
- Mujeeb ur Rahman
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China; (M.u.R.); (Q.S.); (C.L.); (Y.S.); (Y.L.)
| | - Weixiao Wang
- Clinical Research Center, The Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing 210003, China;
| | - Qingqing Sun
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China; (M.u.R.); (Q.S.); (C.L.); (Y.S.); (Y.L.)
| | - Junaid Ali Shah
- College of Life Sciences, Jilin University, Changchun 130012, China;
| | - Chao Li
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China; (M.u.R.); (Q.S.); (C.L.); (Y.S.); (Y.L.)
| | - Yanmei Sun
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China; (M.u.R.); (Q.S.); (C.L.); (Y.S.); (Y.L.)
| | - Yuanrui Li
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China; (M.u.R.); (Q.S.); (C.L.); (Y.S.); (Y.L.)
| | - Bailing Zhang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China;
| | - Wei Chen
- Clinical Research Center, The Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing 210003, China;
| | - Shiwei Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi’an 710069, China; (M.u.R.); (Q.S.); (C.L.); (Y.S.); (Y.L.)
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6
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Cunha AP, Henriques R, Cardoso S, Freitas PP, Carvalho CM. Rapid and multiplex detection of nosocomial pathogens on a phage-based magnetoresistive lab-on-chip platform. Biotechnol Bioeng 2021; 118:3164-3174. [PMID: 34037981 DOI: 10.1002/bit.27841] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/06/2021] [Accepted: 05/16/2021] [Indexed: 11/11/2022]
Abstract
Nosocomial or hospital-acquired infections (HAIs) have a major impact on mortality worldwide. Enterococcus and Staphylococcus are among the leading causes of HAIs and thus are important pathogens to control mainly due to their increased antibiotic resistance. The gold-standard diagnostic methods for HAIs are time-consuming, which hinders timely and adequate treatment. Therefore, the development of fast and accurate diagnostic tools is an urgent demand. In this study, we combined the sensitivity of magnetoresistive (MR) sensors, the portability of a lab-on-chip platform, and the specificity of phage receptor binding proteins (RBPs) as probes for the rapid and multiplex detection of Enterococcus and Staphylococcus. For this, bacterial cells were firstly labelled with magnetic nanoparticles (MNPs) functionalized with RBPs and then measured on the MR sensors. The results indicate that the RBP-MNPS provided a specific individual and simultaneous capture of more than 70% of Enterococcus and Staphylococcus cells. Moreover, high signals from the MR sensors were obtained for these samples, providing the detection of both pathogens at low concentrations (10 CFU/ml) in less than 2 h. Overall, the lab-on-chip MR platform herein presented holds great potential to be used as a point-of-care for the rapid, sensitive and specific multiplex diagnosis of bacterial infections.
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Affiliation(s)
- Alexandra P Cunha
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal.,Centre of Biological Engineering (CEB), University of Minho, Braga, Portugal
| | - Raquel Henriques
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC MN) and IN - Institute of Nanoscience and Nanotechnology, Lisbon, Portugal
| | - Susana Cardoso
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC MN) and IN - Institute of Nanoscience and Nanotechnology, Lisbon, Portugal
| | - Paulo P Freitas
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal.,Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC MN) and IN - Institute of Nanoscience and Nanotechnology, Lisbon, Portugal
| | - Carla M Carvalho
- International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
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7
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Wu X, Han J, Gong G, Koffas MAG, Zha J. Wall teichoic acids: physiology and applications. FEMS Microbiol Rev 2020; 45:6019871. [DOI: 10.1093/femsre/fuaa064] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 12/01/2020] [Indexed: 12/21/2022] Open
Abstract
ABSTRACT
Wall teichoic acids (WTAs) are charged glycopolymers containing phosphodiester-linked polyol units and represent one of the major components of Gram-positive cell envelope. WTAs have important physiological functions in cell division, gene transfer, surface adhesion, drug resistance and biofilm formation, and are critical virulence factors and vital determinants in mediating cell interaction with and tolerance to environmental factors. Here, we first briefly introduce WTA structure, biosynthesis and its regulation, and then summarize in detail four major physiological roles played by WTAs, i.e. WTA-mediated resistance to antimicrobials, virulence to mammalian cells, interaction with bacteriolytic enzymes and regulation of cell metabolism. We also review the applications of WTAs in these fields that are closely related to the human society, including antibacterial drug discovery targeting WTA biosynthesis, development of vaccines and antibodies regarding WTA-mediated pathogenicity, specific and sensitive detection of pathogens in food using WTAs as a surface epitope and regulation of WTA-related pathways for efficient microbial production of useful compounds. We also point out major problems remaining in these fields, and discuss some possible directions in the future exploration of WTA physiology and applications.
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Affiliation(s)
- Xia Wu
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Jing Han
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Guoli Gong
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Mattheos A G Koffas
- Center for Biotechnology and Interdisciplinary Studies, Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Jian Zha
- School of Food and Biological Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
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8
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Characterization of medical relevant anaerobic microorganisms by isothermal microcalorimetry. Anaerobe 2020; 66:102282. [PMID: 33017653 DOI: 10.1016/j.anaerobe.2020.102282] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 09/27/2020] [Accepted: 10/01/2020] [Indexed: 12/20/2022]
Abstract
Detection of anaerobe bacteria by culture methods requires appropriate media, special growth conditions, additional detection techniques and it typically takes several days. Therefore, anaerobes are often missed in patient specimens under routine culture conditions. Microcalorimetry may provide a simple and accurate real-time method for faster and better detection of anaerobes. An isothermal calorimeter which detect minimal changes of temperature over time was used for the calorimetric experiments. In order to find optimal growth conditions, seven reference or clinical strains of medical relevant anaerobe bacteria were tested under different circumstances. First, the strains were tested with different growth media. After determining the optimal medium for each strain, the gas phase was modified by adding 3 mL or 4 mL medium, to evaluate growth under conditions with less oxygen. Cooked Meat Medium was best supporting growth of the tested strains, including Cutibacterium acnes, Fusobacterium nucleatum, Finegoldia magna, Parvimonas micra, Bacteroides fragilis and Actinomyces odontolyticus, followed by thioglycolate. The best medium to detect Clostridioides difficile was H-Medium. All tested strains showed better growth in 4 mL medium than in 3 mL. The detection time ranged between 10 and 72 h. Our results demonstrated that the sensitivity and the detection time of anaerobe bacteria can be improved by isothermal calorimetry with optimization of growth conditions. Therefore, calorimetric detection, a practical, quick and easy-to-do method, has the potential to replace current microbiological methods.
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9
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Opportunities for broadening the application of cell wall lytic enzymes. Appl Microbiol Biotechnol 2020; 104:9019-9040. [DOI: 10.1007/s00253-020-10862-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 08/14/2020] [Accepted: 08/26/2020] [Indexed: 01/21/2023]
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10
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Huo B, Hu Y, Gao Z, Li G. Recent advances on functional nucleic acid-based biosensors for detection of food contaminants. Talanta 2020; 222:121565. [PMID: 33167261 DOI: 10.1016/j.talanta.2020.121565] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 02/06/2023]
Abstract
It has seen increasing development of reliable, robust, and flexible biosensors for rapid food-safety analysis in the past few decades. Recently, functional nucleic acid-based biosensors have attracted attention because of their programmability, bottom-up characteristics, and structural switches. However, few systematic reviews devoted to categorizing the potential of DNA nanostructures and devices were found for detecting food contaminants. Hence, the applications of functional nucleic acid-based biosensors were reviewed for analyzing food contaminants, including foodborne pathogen bacteria, biotoxins, heavy metals, and et al. In addition to categorizing the various biosensors, multiple signal readout strategies, such as optical, electrochemical, and mass-based signals were also examined. Finally, the future changes and potential opportunities, as well as practical applications of functional nucleic acid-based biosensors were discussed.
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Affiliation(s)
- Bingyang Huo
- School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, China
| | - Yuling Hu
- School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, China
| | - Zhixian Gao
- Tianjin Key Laboratory of Risk Assessment and Control Technology for Environment and Food Safety, Tianjin Institute of Environmental and Operational Medicine, Tianjin, 300050, China
| | - Gongke Li
- School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, China.
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11
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Huang F, Xue L, Zhang H, Guo R, Li Y, Liao M, Wang M, Lin J. An enzyme-free biosensor for sensitive detection of Salmonella using curcumin as signal reporter and click chemistry for signal amplification. Am J Cancer Res 2018; 8:6263-6273. [PMID: 30613296 PMCID: PMC6299696 DOI: 10.7150/thno.29025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/17/2018] [Indexed: 01/08/2023] Open
Abstract
In this study, an enzyme-free biosensor was developed for sensitive and specific detection of Salmonella typhimurium (S. typhimurium) using curcumin (CUR) as signal reporter and 1,2,4,5-tetrazine (Tz)-trans-cyclooctene (TCO) click chemistry for signal amplification. Methods: Nanoparticles composed of CUR and bovine serum albumin (BSA) were formulated and reacted with Tz and TCO to form Tz-TCO-CUR conjugates through Tz-TCO click chemistry. Then, the Tz-TCO-CUR conjugates were functionalized with polyclonal antibodies (pAbs) against S. typhimurium to form CUR-TCO-Tz-pAb conjugates. Magnetic nanoparticles (MNPs) conjugated with monoclonal antibodies (mAbs) against S. typhimurium through streptavidin-biotin binding were used to specifically and efficiently separate S. typhimurium from the background by magnetic separation. CUR-TCO-Tz-pAb conjugates were reacted with the magnetic bacteria to form CUR-Tz-TCO bacteria. Finally, CUR was released quickly from the CUR-Tz-TCO bacteria in the presence of NaOH, and the color change was measured at the characteristic wavelength of 468 nm for bacteria quantification. Results: A linear relationship between absorbance at 468 nm and concentration of S. typhimurium from 102 to 106 CFU/mL was found. The lower detection limit was calculated to be as low as 50 CFU/mL and the mean recovery was 107.47% for S. typhimurium in spiked chicken samples. Conclusion: This biosensor has the potential for practical applications in the detection of foodborne pathogens.
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