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Singh S, Chowdhury P, Ghosh A, Nara S. Virtual screening of truncated single stranded DNA aptamers for Staphylococcal enterotoxin type A. J Biomol Struct Dyn 2023; 41:11862-11871. [PMID: 36597903 DOI: 10.1080/07391102.2022.2164057] [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: 08/29/2022] [Accepted: 12/24/2022] [Indexed: 01/05/2023]
Abstract
Single stranded DNA (ssDNA)/RNA aptamers, are screened through the labor intensive, iterative Systematic Evolution of Ligand by Exponential Enrichment process (SELEX) method. Complete sequence of screened aptamers never interacts with target or participates in final structure. Hence, in silico tools can be used to redesign a short length aptamer from previously reported aptamers which can have high affinity and specificity to the target. This approach is fast, cost effective, and less laborious than in vitro SELEX towards finding an aptamer sequence with better affinity with the target. Here, Staphylococcal enterotoxin type A (SEA) was used as target. A total of nine aptamers reported for different Staphylococcal food poisoning (SFP) enterotoxins were used as a starting pool. The aptamers were variously truncations and thoroughly analyzed through in silico methods. Three truncated aptamers namely AptSEA1.4, AptSEA2.4 and AptSEA8.4 were found to show higher affinity with target SEA. The computational data was also validated with DOT BLOT assay complemented with image analysis. These results also confirmed that the % specific binding and the dissociation constant (Kd) of truncated aptamers AptSEA1.4, AptSEA2.4 and AptSEA8.4 was better than their original counterparts. The truncated aptamers showed great promise to be used as a capture reagent in developing a sensitive assay for detection of SEA.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Smriti Singh
- Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, Uttar Pradesh, India
| | - Papia Chowdhury
- Department of Physics and Material Science, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, India
| | - Arabinda Ghosh
- Microbiology Division, Department of Botany, Guwahati University, Guwahati, Assam, India
| | - Seema Nara
- Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, Uttar Pradesh, India
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2
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Nikam PS, Palachandra S, Kingston JJ. In vitro selection and characterization of ssDNA aptamers by cross-over SELEX and its application for detection of S. Typhimurium. Anal Biochem 2022; 656:114884. [DOI: 10.1016/j.ab.2022.114884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 08/10/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022]
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3
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Kohlberger M, Gadermaier G. SELEX: Critical factors and optimization strategies for successful aptamer selection. Biotechnol Appl Biochem 2022; 69:1771-1792. [PMID: 34427974 PMCID: PMC9788027 DOI: 10.1002/bab.2244] [Citation(s) in RCA: 77] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 08/22/2021] [Indexed: 12/30/2022]
Abstract
Within the last decade, the application range of aptamers in biochemistry and medicine has expanded rapidly. More than just a replacement for antibodies, these intrinsically structured RNA- or DNA-oligonucleotides show great potential for utilization in diagnostics, specific drug delivery, and treatment of certain medical conditions. However, what is analyzed less frequently is the process of aptamer identification known as systematic evolution of ligands by exponential enrichment (SELEX) and the functional mechanisms that lie at its core. SELEX involves numerous singular processes, each of which contributes to the success or failure of aptamer generation. In this review, critical steps during aptamer selection are discussed in-depth, and specific problems are presented along with potential solutions. The discussed aspects include the size and molecule type of the selected target, the nature and stringency of the selection process, the amplification step with its possible PCR bias, the efficient regeneration of RNA or single-stranded DNA, and the different sequencing procedures and screening assays currently available. Finally, useful quality control steps and their role within SELEX are presented. By understanding the mechanisms through which aptamer selection is influenced, the design of more efficient SELEX procedures leading to a higher success rate in aptamer identification is enabled.
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Affiliation(s)
- Michael Kohlberger
- Department of BiosciencesParis Lodron University SalzburgSalzburgAustria,Christian Doppler Laboratory for Biosimilar CharacterizationParis Lodron University SalzburgSalzburgAustria
| | - Gabriele Gadermaier
- Department of BiosciencesParis Lodron University SalzburgSalzburgAustria,Christian Doppler Laboratory for Biosimilar CharacterizationParis Lodron University SalzburgSalzburgAustria
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4
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Banu K, Mondal B, Rai B, Monica N, Hanumegowda R. Prospects for the application of aptamer based assay platforms in pathogen detection. Biocybern Biomed Eng 2022. [DOI: 10.1016/j.bbe.2022.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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5
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Lavu PS, Mondal B, Ramlal S. Selection and Characterization of Cell Surface Specific Aptamer and Development of Fluorescence Assay for Detection of Shigella flexneri from Water Samples. J Fluoresc 2021; 31:685-693. [PMID: 33582948 DOI: 10.1007/s10895-021-02691-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/25/2021] [Indexed: 10/22/2022]
Abstract
The present study demonstrates, development of ssDNA aptamers against whole cell of S. flexneri employing a whole bacterium-based Systemic Evolution of Ligands by Exponential Enrichment (SELEX). After ten rounds of SELEX, cell surface specific aptamer pool was cloned, sequenced and divided based on sequence similarities and secondary structure. Binding affinity of FITC labelled aptamer from different group were carried out by flow cytometry analysis. The dissociation constant (Kd) values for specific and higher binder were evaluated to range from 144 to 329 nM. Six high binding aptamers with lower dissociation constant was chosen for selectivity study. Aptamer SHI 23, SHI 37 and SHI 42 showed higher selectivity towards S. flexneri in comparison with other related bacteria. Further applicability of selected aptamer was proven by fluorescence assay for convenience detection of target cell from spiked water sample and natural contaminated water samples. Altogether, aptamer generated in this study can be alternative DNA ligands for detection of S. flexneri compared to available ligands.
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Affiliation(s)
- Padma Sudharani Lavu
- Microbiology Division, Defence Food Research Laboratory, Siddharthanagar, Mysore, Karnataka, 570011, India
| | - Bhairab Mondal
- Microbiology Division, Defence Food Research Laboratory, Siddharthanagar, Mysore, Karnataka, 570011, India
| | - Shylaja Ramlal
- Microbiology Division, Defence Food Research Laboratory, Siddharthanagar, Mysore, Karnataka, 570011, India.
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Yi J, Xiao W, Li G, Wu P, He Y, Chen C, He Y, Ding P, Kai T. The research of aptamer biosensor technologies for detection of microorganism. Appl Microbiol Biotechnol 2020; 104:9877-9890. [PMID: 33047168 DOI: 10.1007/s00253-020-10940-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 09/27/2020] [Accepted: 10/01/2020] [Indexed: 12/21/2022]
Abstract
The activities and transmissions of microorganisms are closely related to human, and all kinds of diseases caused by pathogenic microorganisms have attracted attention in the world and brought many challenges to human health and public health. The traditional microbial detection technologies have characteristics of longer detection cycle and complicated processes, therefore, which can no longer meet the detection requirements in the field of public health. At present, it is the focus to develop and design a novel, rapid, and simple microbial detection method in the field of public health. Herein, this article summarized the development of aptamer biosensor technologies for detection of microorganism in the aspect of bacteria, viruses, and toxins in detail, including optical aptamer sensors such as fluorometry and colorimetry, electrochemical aptamer sensors, and other technologies combined with aptamer. KEY POINTS: • Aptamer biosensor is a good platform for microbial detection. • Aptamer biosensors include optical sensors and electrochemical sensors. • Aptamer sensors have been widely used in the detection of bacteria, viruses, and other microorganisms.
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Affiliation(s)
- Jiecan Yi
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China.,School of Public Health, Changsha Medical University, Changsha, 410219, Hunan, China
| | - Wen Xiao
- Hunan Institute of Food Quality Supervision Inspection and Research, Changsha, 410000, Hunan, China
| | - Guiyin Li
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, 541014, Guangxi, China
| | - Pian Wu
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Yayuan He
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Cuimei Chen
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Yafei He
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Ping Ding
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China.
| | - Tianhan Kai
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410078, Hunan, China.
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Mojarad AE, Gargaria SLM. Aptamer-nanobody based ELASA for detection of Vibrio cholerae O1. IRANIAN JOURNAL OF MICROBIOLOGY 2020; 12:263-272. [PMID: 32994896 PMCID: PMC7502147 DOI: 10.18502/ijm.v12i4.3928] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background and Objectives In recent years, the prevalence of diseases caused by Vibrio spp. is increasing in the world, and among them species, Vibrio cholerae is the most important Vibrio associated with pandemic and epidemic cholera outbreaks. Therefore, the development of a reliable method for early and accurate detection of V. cholerae for management of diseases is a real need. Aptamers with the ability to detect targets with high specificity and accuracy can be one of the candidates used for the whole cell and thereby V. cholerae detection. Materials and Methods In this research high-affinity DNA aptamers against with two major serotypes of Inaba (ATCC 39315) and Ogawa (clinical sample) were selected from DNA aptamer library through 12 rounds of Systematic Evolution of Ligands by Exponential (SELEX) enrichment procedure using live cells as a target which monitored with flow cytometry. Results The binding efficiency and dissociation constant of the isolated aptamers V.ch47 and V.ch27 were 56.4%, 53.3% and 15.404 ± 4.776 pM, 20.186 ± 3.655 pM, respectively. A sandwich Enzyme-linked aptamer sorbent assay (ELASA) was developed with the biotinylated V.ch47 aptamer and our previously developed nanobody anti-Lipopolysaccharides (LPS). We optimized this system with V. cholerae O1 and analyzed their cross reactivity with close physiological bacteria. The threshold of detection was obtained 104 CFU/ml in the sandwich ELASA process. Conclusion Our results showed that the sandwich ELASA is sensitive enough for the rapid detection of V. cholerae from other bacteria.
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Cui F, Sun J, de Dieu Habimana J, Yang X, Ji J, Zhang Y, Lei H, Li Z, Zheng J, Fan M, Sun X. Ultrasensitive Fluorometric Angling Determination of Staphylococcus aureus in Vitro and Fluorescence Imaging in Vivo Using Carbon Dots with Full-Color Emission. Anal Chem 2019; 91:14681-14690. [PMID: 31617347 DOI: 10.1021/acs.analchem.9b03916] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rapid, accurate, and safe screening of foodborne pathogenic bacteria is essential to effectively control and prevent outbreaks of foodborne illness. Fluorescent sensors constructed from carbon dots (CDs) and nanomaterial-based quenchers have provided an innovative method for screening of pathogenic bacteria. Herein, an ultrasensitive magnetic fluorescence aptasensor was designed for separation and detection of Staphylococcus aureus (S. aureus). Multicolor fluorescent CDs with a long fluorescent lifetime (6.73 ns) and high fluorescence stability were synthesized using a facile hydrothermal approach and modified cDNA as a highly sensitive fluorescent probe. CD fluorescence was quenched by Fe3O4 + aptamer via fluorescence resonance energy transfer (FRET). Under optimal conditions, the FRET-based aptasensor can detect S. aureus accompanied by a wide linear range of 50-107 CFU·mL-1 and a detection limit of 8 CFU·mL-1. Compared with other standard methods, this method was faster and more convenient, and the entire test was finished within 30 min. The capability of the aptasensor was simultaneously investigated on food samples. Additionally, the developed CDs exhibited excellent biocompatibility and were thus applied as fluorescent probes for bioimaging both in vitro and in vivo. This new platform provided an excellent application of the CDs for detecting and bioimaging pathogenic bacteria.
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Affiliation(s)
- Fangchao Cui
- School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, Synergetic Innovation Center of Food Safety and Nutrition , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Jiadi Sun
- School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, Synergetic Innovation Center of Food Safety and Nutrition , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Jean de Dieu Habimana
- School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, Synergetic Innovation Center of Food Safety and Nutrition , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Xingxing Yang
- School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, Synergetic Innovation Center of Food Safety and Nutrition , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Jian Ji
- School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, Synergetic Innovation Center of Food Safety and Nutrition , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Yinzhi Zhang
- School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, Synergetic Innovation Center of Food Safety and Nutrition , Jiangnan University , Wuxi , Jiangsu 214122 , China
| | - Hongtao Lei
- Key Laboratory of Food Quality and Safety of Guangdong Province, College of Food Science , South China Agricultural University , Guangzhou 510642 , China
| | - Zaijun Li
- School of Chemical and Material Engineering , Jiangnan University , Wuxi 214122 , China
| | - Jiayu Zheng
- National Quality Supervision & Testing Center for Organic Food , Baoying 225800 , China
| | - Minghong Fan
- National Quality Supervision & Testing Center for Organic Food , Baoying 225800 , China
| | - Xiulan Sun
- School of Food Science, State Key Laboratory of Food Science and Technology, National Engineering Research Center for Functional Foods, Synergetic Innovation Center of Food Safety and Nutrition , Jiangnan University , Wuxi , Jiangsu 214122 , China
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9
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Yi J, Wu P, Li G, Xiao W, Li L, He Y, He Y, Ding P, Chen C. A composite prepared from carboxymethyl chitosan and aptamer-modified gold nanoparticles for the colorimetric determination of Salmonella typhimurium. Mikrochim Acta 2019; 186:711. [PMID: 31650251 DOI: 10.1007/s00604-019-3827-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 09/14/2019] [Indexed: 11/27/2022]
Abstract
An aptamer-based assay is described for the determination of Salmonella typhimurium (S. typh). Carboxymethyl chitosan was loaded with amino-modified aptamer against S. typh, and then adsorbed on gold nanoparticles by electrostatic interaction to form a composite that acts as the molecular recognition element. In the presence of S. typh, it will be bound by the aptamer, and this changes the structure of the recognition element. On addition of salt solution, the gold nanoparticles agglomerate so that the color of the solution changes from red to blue. S. typh can be detected via measurement of the absorbance at 550 nm. Absorbance increases linearly with the logarithm of the S. typh concentration in the range from 100 to 109 cfu·mL-1. The limit of detection is 16 cfu·mL-1. The specificity and practicability of the assay were evaluated. The recoveries of S. typh from spiked milk samples are between 92.4 and 97.2%. The analytical results are basically consistent with those of a plate counting method. Graphical abstract Schematic representation of the colorimetric assay for Salmonella typhimuium (S. typh) using carboxymethyl chitosan (CMCS)-aptamer (Apt)-gold nanoparticles (AuNPs) composites.
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Affiliation(s)
- Jiecan Yi
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Pian Wu
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Guiyin Li
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, 541014, Guangxi, China
| | - Wen Xiao
- Hunan Institute of Food Quality Supervision Inspection and Research, Changsha, 410000, Hunan, China
| | - Lei Li
- Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, China
| | - Yayuan He
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Yafei He
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China
| | - Ping Ding
- Xiang Ya School of Public Health, Central South University, Changsha, 410078, Hunan, China.
| | - Cuimei Chen
- School of Public Health, Xiangnan University, Chenzhou, 423000, Hunan, China.
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Komarova N, Kuznetsov A. Inside the Black Box: What Makes SELEX Better? Molecules 2019; 24:E3598. [PMID: 31591283 PMCID: PMC6804172 DOI: 10.3390/molecules24193598] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 10/04/2019] [Accepted: 10/04/2019] [Indexed: 02/07/2023] Open
Abstract
Aptamers are small oligonucleotides that are capable of binding specifically to a target, with impressive potential for analysis, diagnostics, and therapeutics applications. Aptamers are isolated from large nucleic acid combinatorial libraries using an iterative selection process called SELEX (Systematic Evolution of Ligands by EXponential enrichment). Since being implemented 30 years ago, the SELEX protocol has undergone many modifications and improvements, but it remains a laborious, time-consuming, and costly method, and the results are not always successful. Each step in the aptamer selection protocol can influence its results. This review discusses key technical points of the SELEX procedure and their influence on the outcome of aptamer selection.
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Affiliation(s)
- Natalia Komarova
- Scientific-Manufacturing Complex Technological Centre, 1-7 Shokin Square, Zelenograd, Moscow 124498, Russia.
| | - Alexander Kuznetsov
- Scientific-Manufacturing Complex Technological Centre, 1-7 Shokin Square, Zelenograd, Moscow 124498, Russia.
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Mondal B, N B, Ramlal S, Kingston J. Colorimetric DNAzyme Biosensor for Convenience Detection of Enterotoxin B Harboring Staphylococcus aureus from Food Samples. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:1516-1522. [PMID: 29350529 DOI: 10.1021/acs.jafc.7b04820] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In the present study, a colorimetric DNAzymes biosensor strategy was devised in combination with immunomagnetic separation for rapid and easy detection of enterotoxin B harboring Staphylococcus aureus from food and clinical samples. The method employs immunocapture of S. aureus and amplification of seb gene by DNAzyme complementary sequence integrated forward primer and with specific reverse primer. The DNAzyme sequence integrated dsDNA PCR products when treated with hemin and TMB (3,3',5,5'-tetramethylbenzidine) in the presence of H2O2 produce colorimetric signal. A linear relationship of optical signal with the initial template of seb was obtained which could be monitored by visually or spectrophotrometrically for qualitative and quantitative detection. The limit of detection for the assay was approximately 102 CFU/mL of seb gene harboring target. This method is convenient compared to gel based and ELISA systems. Further, spiking studies and analysis on natural samples emphasized the robustness and applicability of developed method. Altogether, the established assay could be a reliable alternative, low-cost, viable detection tool for the routine investigation of seb from food and clinical sources.
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Affiliation(s)
- Bhairab Mondal
- Defence Food Research Laboratory , Microbiology Division, Siddarthanagar, Mysore, Karnataka 570011, India
| | - Bhavanashri N
- Defence Food Research Laboratory , Microbiology Division, Siddarthanagar, Mysore, Karnataka 570011, India
| | - Shylaja Ramlal
- Defence Food Research Laboratory , Microbiology Division, Siddarthanagar, Mysore, Karnataka 570011, India
| | - Joseph Kingston
- Defence Food Research Laboratory , Microbiology Division, Siddarthanagar, Mysore, Karnataka 570011, India
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12
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Mondal B, Ramlal S, Lavu PS, N B, Kingston J. Highly Sensitive Colorimetric Biosensor for Staphylococcal Enterotoxin B by a Label-Free Aptamer and Gold Nanoparticles. Front Microbiol 2018; 9:179. [PMID: 29487580 PMCID: PMC5816949 DOI: 10.3389/fmicb.2018.00179] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 01/25/2018] [Indexed: 11/20/2022] Open
Abstract
A simple, sensitive and selective colorimetric biosensor for the detection of Staphylococcal enterotoxin B (SEB) was developed using SEB-binding aptamer (SEB2) as recognition element and unmodified gold nanoparticles (AuNPs) as colorimetric probes. The assay is based on color change from red to purple due to conformational change of aptamer in the presence of SEB, and the phenomenon of salt-induced AuNPs aggregation which could be monitored by naked eye or UV–vis spectrometer. Results showed that the AuNPs can effectively differentiate the SEB induced conformational change of the aptamer in the presence of a given high salt concentration. A linear response in the range of 50 μg/mL to 0.5 ng/mL of SEB concentration was obtained. The assay was highly specific to SEB as compared to other related toxins. The limit of detection (LOD) of SEB achieved within few minutes was 50 ng/mL visually and spectrometric method improved it to 0.5 ng/mL. Robustness of the assay was tested in artificially spiked milk samples and cross-checked using in house developed sandwich ELISA (IgY as capturing and SEB specific monoclonal as revealing antibody) and PCR. This colorimetric assay could be a suitable alternative over existing methods during biological emergencies due to its simplicity, sensitive and cost effectiveness.
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Affiliation(s)
- Bhairab Mondal
- Microbiology Division, Defence Food Research Laboratory, Mysore, India
| | - Shylaja Ramlal
- Microbiology Division, Defence Food Research Laboratory, Mysore, India
| | - Padma S Lavu
- Microbiology Division, Defence Food Research Laboratory, Mysore, India
| | - Bhavanashri N
- Microbiology Division, Defence Food Research Laboratory, Mysore, India
| | - Joseph Kingston
- Microbiology Division, Defence Food Research Laboratory, Mysore, India
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13
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Ramlal S, Mondal B, Lavu PS, N B, Kingston J. Capture and detection of Staphylococcus aureus with dual labeled aptamers to cell surface components. Int J Food Microbiol 2017; 265:74-83. [PMID: 29132030 DOI: 10.1016/j.ijfoodmicro.2017.11.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/22/2017] [Accepted: 11/04/2017] [Indexed: 11/18/2022]
Abstract
In the present study, a high throughput whole cell SELEX method has been applied successfully in selecting specific aptamers against whole cells of Staphylococcus aureus, a potent food poisoning bacterium. A total ten rounds of SELEX and three rounds of intermittent counter SELEX, was performed to obtain specific aptamers. Obtained oligonucleotide pool were cloned, sequenced and then grouped into different families based on their primary sequence homology and secondary structure similarity. FITC labeled sequences from different families were selected for further characterization via flow cytometry analysis. The dissociation constant (Kd) values of specific and higher binders ranged from 34 to 128nM. Binding assays to assess the selectivity of aptamer RAB10, RAB 20, RAB 28 and RAB 35 demonstrated high affinity against S. aureus and low binding affinity for other bacteria. To demonstrate the potential use of the aptamer a sensitive dual labeled sandwich detection system was developed using aptamer RAB10 and RAB 35 with a detection limit of 102CFU/mL. Furthermore detection from mixed cell population and spiked sample emphasized the robustness as well as applicability of the developed method. Altogether, the established assay could be a reliable detection tool for the routine investigation of Staphylococcus aureus in samples from food and clinical sources.
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Affiliation(s)
- Shylaja Ramlal
- Microbiology Division, Defence Food Research Laboratory, Siddarthanagar, Mysore, Karnataka 570011, India.
| | - Bhairab Mondal
- Microbiology Division, Defence Food Research Laboratory, Siddarthanagar, Mysore, Karnataka 570011, India
| | - Padma Sudharani Lavu
- Microbiology Division, Defence Food Research Laboratory, Siddarthanagar, Mysore, Karnataka 570011, India
| | - Bhavanashri N
- Microbiology Division, Defence Food Research Laboratory, Siddarthanagar, Mysore, Karnataka 570011, India
| | - Joseph Kingston
- Microbiology Division, Defence Food Research Laboratory, Siddarthanagar, Mysore, Karnataka 570011, India
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14
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Sharma TK, Bruno JG, Dhiman A. ABCs of DNA aptamer and related assay development. Biotechnol Adv 2017; 35:275-301. [PMID: 28108354 DOI: 10.1016/j.biotechadv.2017.01.003] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/19/2016] [Accepted: 01/17/2017] [Indexed: 12/14/2022]
Abstract
This review is intended to guide the novice in aptamer research and development to understand virtually all of the aptamer development options and currently available assay modalities. Aptamer development topics range from discussions of basic and advanced versions of Systematic Evolution of Ligands by EXponential Enrichment (SELEX) and SELEX variations involving incorporation of exotic unnatural nucleotides to expand library diversity for even greater aptamer affinity and specificity to improved next generation methods of DNA sequencing, screening and tracking aptamer development throughout the SELEX process and characterization of lead aptamer candidates. Aptamer assay development topics include descriptions of various colorimetric and fluorescent assays in microplates or on membranes including homogeneous beacon and multiplexed Fluorescence Resonance Energy Transfer (FRET) assays. Finally, a discussion of the potential for marketing successful aptamer-based assays or test kits is included.
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Affiliation(s)
- Tarun Kumar Sharma
- Center for Biodesign and Diagnostics, Translational Health Science and Technology Institute, Faridabad, Haryana 121001, India; AptaBharat Innovation Private Limited, Translational Health Science and Technology Institute Incubator, Haryana 121001, India.
| | - John G Bruno
- Operational Technologies Corporation, 4100 NW Loop 410, Suite, 230, San Antonio, TX 78229, USA..
| | - Abhijeet Dhiman
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi 110029, India.; Faculty of Pharmacy, Uttarakhand Technical University, Dehradun 248007, Uttarakhand, India
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15
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Setlem K, Mondal B, Ramlal S, Kingston J. Immuno Affinity SELEX for Simple, Rapid, and Cost-Effective Aptamer Enrichment and Identification against Aflatoxin B1. Front Microbiol 2016; 7:1909. [PMID: 27990137 PMCID: PMC5130984 DOI: 10.3389/fmicb.2016.01909] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/15/2016] [Indexed: 01/01/2023] Open
Abstract
Aflatoxins are naturally occurring mycotoxins that contaminate food and agro commodities, leading to acute and chronic health conditions in human and animals. In the present work, an attempt was made to generate high-affinity single stranded DNA aptamers that specifically bind to Aflatoxin B1 (AFB1) by a modified Systemic Evolution of Ligands by Exponential Enrichment (SELEX) procedure with the aid of Immunoaffinity columns. Ten rounds of SELEX and alternating three counter SELEX rounds with a cocktail of related and other mycotoxins were performed to enhance the specificity. Resultant 105 aptamers were clustered into 12 groups according to their primary sequence homology. Candidates with lowest Gibbs free energy (dG value) and unique stem loop structures were selected for further characterization. Aptamers, AFLA5, AFLA53, and AFLA71 exhibiting lower Kd values (50.45 ± 11.06, 48.29 ± 9.45, and 85.02 ± 25.74 nM) were chosen for development of ELONA and determination of purification ability of toxin. The detection limit (LOD) of AFLA5 and AFLA71 was 20 and 40 ng/ml, respectively. HPLC analysis implied that selected aptamers were able to recover and quantify 82.2 to 96.21% (LOQ – 53.74 ng) and 78.3 to 94.22% (LOQ – 66.75 ng) of AFB1 from spiked corn samples, respectively. These findings indicate, immunoaffinity based SELEX can pave an alternative approach to screen aptamers against mycotoxin detection and purification.
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Affiliation(s)
- Keerthana Setlem
- Microbiology Division, Defence Food Research Laboratory Mysore, India
| | - Bhairab Mondal
- Microbiology Division, Defence Food Research Laboratory Mysore, India
| | - Shylaja Ramlal
- Microbiology Division, Defence Food Research Laboratory Mysore, India
| | - Joseph Kingston
- Microbiology Division, Defence Food Research Laboratory Mysore, India
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Alfavian H, Mousavi Gargari SL, Rasoulinejad S, Medhat A. Development of a DNA aptamer that binds specifically to group A Streptococcus serotype M3. Can J Microbiol 2016; 63:160-168. [PMID: 28121169 DOI: 10.1139/cjm-2016-0495] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Group A streptococcus (GAS) is an important Gram-positive pathogen that causes various human diseases ranging from peripheral lesions to invasive infections. The M protein is one of the main virulence factors present on the cell surface and is associated with invasive GAS infections. Compared with other M types, serotype M3 has a predominant role in lethal infections and demonstrates epidemic behaviors, including streptococcal toxic shock syndrome, bacteremia, and necrotizing fasciitis. Traditional methods for M typing are time-consuming, tedious, contradictory, and generally restricted to reference laboratories. Therefore, development of a new M-typing technique is needed. Aptamers with the ability to detect their target with a high degree of accuracy and specificity can be ideal candidates for specific M-typing of Streptococcus pyogenes. In this study DNA aptamers with a high binding affinity towards S. pyogenes serotype M3 were selected through 12 iterative rounds of the Systematic Evolution of Ligands by EXponential (SELEX) enrichment procedure using live cells as a target. We monitored the progress of the SELEX procedure by flow cytometry analysis. Of several aptamer sequences analyzed, 12L18A showed the highest binding efficiency towards S. pyogenes type M3, with an apparent dissociation constant (Kd) of 7.47 ± 1.72 pmol/L being the lowest. Therefore the isolated aptamer can be used in any tool, such as a biosensor, for the detection of S. pyogenes and can be used in the development of a novel M-typing system.
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Affiliation(s)
- Hanif Alfavian
- a Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran
| | | | - Samaneh Rasoulinejad
- a Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran
| | - Arvin Medhat
- b GENEXIR Biopharma, a knowledge-based company at Pasteur Institute of Iran Health Technology Park, Tehran, Iran
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Lavu PSR, Mondal B, Ramlal S, Murali HS, Batra HV. Selection and Characterization of Aptamers Using a Modified Whole Cell Bacterium SELEX for the Detection of Salmonella enterica Serovar Typhimurium. ACS COMBINATORIAL SCIENCE 2016; 18:292-301. [PMID: 27070414 DOI: 10.1021/acscombsci.5b00123] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This study describes the selection of single-stranded DNA (ssDNA) aptamers against Salmonella enterica serovar Typhimurium using a modified whole cell systematic evolution of ligands by exponential enrichment (whole cell SELEX). For evolving specific aptamers, ten rounds of selection to live Salmonella cells, alternating with negative selection against a cocktail of related pathogens, were performed. The resulting highly enriched oligonucleotide pools were sequenced and clustered into eight groups based on primary sequence homology and predicted secondary structure similarity. Fifteen sequences from different groups were selected for further characterization. The binding affinity and specificity of aptamers were determined by fluorescence binding assays. Aptamers (SAL 28, SAL 11, and SAL 26) with dissociation constants of 195 ± 46, 184 ± 43, and 123 ± 23 nM were used to develop a nanogold-based colorimetric detection method and a sedimentation assay. The former showed a better sensitivity limit of 10(2) CFU/mL using aptamer SAL 26. This approach should enable further refinement of diagnostic methods for the detection of Salmonella enterica serovar Typhimurium and of other microbial pathogens.
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Affiliation(s)
| | - Bhairab Mondal
- Defence Food Research Laboratory (DFRL), Mysore 570011, India
| | - Shylaja Ramlal
- Defence Food Research Laboratory (DFRL), Mysore 570011, India
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Rasoulinejad S, Gargari SLM. Aptamer-nanobody based ELASA for specific detection of Acinetobacter baumannii isolates. J Biotechnol 2016; 231:46-54. [PMID: 27234880 DOI: 10.1016/j.jbiotec.2016.05.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/12/2016] [Accepted: 05/19/2016] [Indexed: 11/26/2022]
Abstract
Acinetobacter baumannii has turned into an important threat in nosocomial outbreak infections and multidrug resistance leading to high mortality rates in the 21st century. In recent years its mortality has increased by 15% which in part could be due to lack of a rapid and sensitive diagnostic test. In this work we introduced a new detection test for A. baumannii with two highly specific aptamer and nanobody molecules. High binding affinity DNA oligonucleotide aptamers toward A. baumannii were selected through 12 rounds of whole cell System Evolution of Ligands by EXponential enrichment process (SELEX). The SELEX procedures was monitored by flow cytometry. The dissociation constant and binding efficiency of the selected aptamer Aci49 was 7.547±1:353pM and 47.50%, respectively. A sandwich enzyme linked aptamer sorbent assay (ELASA) was designed with the biotinylated Aci49 aptamer and our previously developed nanobody against biofilm associated protein (Bap). The assay system was optimized with A. baumannii (ATCC 19606) and 47 clinical isolates of A. baumannii were tested. The threshold of detection in sandwich ELASA process was10(3) CFU/ml. The sensitivity of test toward the clinical isolates was 95.47%. Our results reveal that the sandwich ELASA is sensitive and specific enough for the rapid detection of A. baumannii from clinical isolates.
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