Fluorescent aptasensor for the determination of Salmonella typhimurium based on a graphene oxide platform

We report on an aptamer with high affinity against Salmonella typhimurium (S. typhimurium) and selected from an enriched oligonucleotide pool by a whole-cell SELEX process in a method for the fluorimetric determination of S. typhimurium using a graphene oxide platform. In the absence of target, the fluorescence was fairly weak as result of the FAM-labeled aptamer adjacent to graphene oxide. If, however, the fluorophore is released from the graphene oxide due to the formation of the target/aptamer complexes, fluorescence intensity is substantially increased. Under the optimum conditions, the assay displays a linear response to bacteria in the concentration range from 1 × 103 to 1 × 108 CFU·mL−1, with a detection limit of 100 CFU·mL−1. The method is selective in that fluorescence is not much enhanced in case of other bacteria. This aptasensor displays higher sensitivity and selectivity than others and is believed to possess a large potential with respect to the rapid detection of bacteria.