Label-free visual biosensor based on cascade amplification for the detection of Salmonella.
Salmonella is a widely distributed, extremely harmful bacteria, the presence of which requires confirmation via an on-site visual biosensor. In this study, we constructed a label-free, cascade amplification visualization biosensor for the sensitive and rapid detection of Salmonella enterica subsp. enterica serovar typhimurium based on the RDTG principle (recombinase polymerase amplification (RPA), duplex-specific enzyme (DSN) cleavage, terminal deoxynucleotidyl transferase (TdT) extension and G-quadruplexes output). Following DNA extraction of Salmonella spp., the first step in the construction involved the recognition and amplification of nucleic acids, carried out by RPA, to achieve the first signal amplification within 10 min. This RPA product was then specifically cleaved by DSN to produce a large number of small double-stranded DNA (dsDNA) products with 3'-OH within 15 min to achieve the second signal amplification. Thereafter, TdT was employed to empower these small 3'-OH dsDNA products to extend and produce a large number of long G-rich single-stranded DNAs (ssDNAs) within 20 min, thus realizing the third signal increase. These long G-rich ssDNA products displayed a color change that could be directly observed through the naked eye by adding H2O2/3,3',5,5'-tetramethylbenzidine (TMB). The RDTG biosensor for the detection of Salmonella spp. has several advantages, including a low limit of 6 cfu/mL. It is an isothermal-free instrument, simple to operate, with a rapid detection time of less than 1.5 h. Furthermore, it can be visually characterized and quantified by a microplate reader to detect Salmonella spp., in food and environmental samples, and it has broad application prospects.
['Zhang|Yuan|Y|', 'Tian|Jingjing|J|', 'Li|Kai|K|', 'Tian|Hongtao|H|', 'Xu|Wentao|W|']
D015373:Bacterial Typing Techniques D001560:Benzidines D015374:Biosensing Techniques D004253:DNA Nucleotidylexotransferase D004269:DNA, Bacterial D004277:DNA, Single-Stranded D005506:Food Contamination D005516:Food Microbiology D054856:G-Quadruplexes D006861:Hydrogen Peroxide D057230:Limit of Detection D021141:Nucleic Acid Amplification Techniques D045522:Recombinases D012475:Salmonella D012680:Sensitivity and Specificity D015014:Yogurt
Visual biosensor Cascade amplification Salmonella Recombinase polymerase amplification (RPA) Terminal deoxynucleotidyl transferase (TdT) Duplex-specific nuclease (DSN)