Aptamer-AuNP-conjugated carboxymethyl chitosan-functionalized graphene oxide for colorimetric identification of Salmonella typhimurium.

Abstract

Anovel aptamer-AuNP-conjugated carboxymethyl chitosan-functionalized graphene oxide (CMC/GO@Apt-Au NP) probe was for the first timedeveloped for the determination of Salmonella typhimurium (S. typhimurium). Owing to the conformational change of the aptamers in the presence of S. typhimurium, the Au NPs, which were pre-adsorbed on the aptamers through van der Waals forces, were released into the solution phase and induced the color change of the solution. As a result, S. typhimurium ranging from 102 to 107CFU/mL was successfully identified using the designed assay with a limit of detection (LOD) of 10CFU/mL. This low detection level allowed the sensitive recognition of S. typhimurium in milk samples within 40min without sample pretreatment, a conclusion that agreed well with the traditional plate counting method. The developed method not only provides a rapid way for the determination of S. typhimurium with simplicity and sensitivity but also shows potential universality in the quantification of other pathogenic microorganisms.