Label-free visual biosensor based on cascade amplification for the detection of Salmonella.

摘要: Abstract 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 label-free, cascade amplification visualization biosensor for sensitive and rapid detection enterica subsp. serovar typhimurium based on RDTG principle (recombinase polymerase (RPA), duplex-specific enzyme (DSN) cleavage, terminal deoxynucleotidyl transferase (TdT) extension G-quadruplexes output). Following DNA extraction spp., first step in construction involved recognition nucleic acids, carried out by RPA, to achieve signal within 10 min. This RPA product was then specifically cleaved DSN produce large number small double-stranded (dsDNA) products with 3′-OH 15 min second amplification. Thereafter, TdT employed empower these dsDNA extend long G-rich single-stranded DNAs (ssDNAs) 20 min, thus realizing third increase. These ssDNA displayed color change that could be directly observed through naked eye adding H2O2/3,3′,5,5′-tetramethylbenzidine (TMB). The spp. has several advantages, including low limit 6 cfu/mL. It isothermal-free instrument, simple operate, time less than 1.5 h. Furthermore, it can visually characterized quantified microplate reader detect food environmental samples, broad application prospects.