Colorimetric determination of Salmonella typhimurium based on aptamer recognition

A sensitive method for the colorimetric determination of Salmonella typhimurium (S. typhimurium) was developed based on aptamer recognition and gold nanoparticles. First, a biotinylated specific aptamer for S. typhimurium was immobilized on avidin-coated microplate wells. Then, target bacteria, a biotinylated aptamer and avidin-catalase were successively introduced into the microplate wells. Finally, hydrogen peroxide and freshly prepared gold(III) chloride trihydrate were added, and the absorbance of the reaction product was measured with a plate reader. Under optimized conditions, there was a linear relationship between the absorbance (A550 nm) and the concentration of S. typhimurium over the range of 101 to 106 cfu mL−1 (R2 = 0.9920), with a detection limit of 10 cfu mL−1. This simple rapid method provided a promising tool for on-site screening of S. typhimurium in raw chicken samples.