Enhancement of the peroxidase-like activity of aptamers modified gold nanoclusters by bacteria for colorimetric detection of Salmonella typhimurium

A colorimetric aptasensor was developed for selective and sensitive detection of Salmonella typhimurium ( S. typhimurium ) based on the enhancement of bacteria for the peroxidase-like activity of dual aptamers modified bovine serum albumin stabilized-gold nanoclusters ( [email protected] ). Micro-sized bacteria was found to be able to capture [email protected] and 3,3′,5,5′-tetramethylbenzidine (TMB), thus promoting the proximity of [email protected] to TMB and greatly increasing the local concentrations of the enzyme-mimetic nanoparticles and their substrate. As a result, addition of bacteria promoted the formation of blue products in the catalytic system, which was utilized to achieve bacteria detection by colorimetry . The parameters influencing the colorimetric aptasensor were optimized by an orthogonal test. Under the selected conditions, the aptasensor exhibited a wide linear response to S. typhimurium in the concentration range of 10 1 –10 6  cfu mL −1 with a detection limit as low as 1 cfu mL −1 . The feasibility of the aptasensor was verified by successful detection of S. typhimurium in egg samples with recoveries in the range of 92.4%–110%.