SERS aptasensor for Salmonella typhimurium detection based on spiny gold nanoparticles

A simple, rapid, selective, and sensitive biosensor was constructed for detection of Salmonella typhimurium (S. typhimurium), based on enhanced Raman intensity using spiny gold nanoparticles (SGNPs). The SGNPs were respectively functionalized with 4-mercaptobenzoic acid (p-MBA, Raman signal molecules) and thiolated S. typhimurium aptamers as SERS nanoprobes. On the other side, the biotinylated aptamer was anchored on the microtiter plate which could realize specific recognition and capture of S. typhimurium. Gradient dilutions of S. typhimurium captured gradient amounts of the SERS nanoprobes. The SERS intensity of p-MBA at 1586 cm−1 was used to successfully measure S. typhimurium (y = 50.6155 + 1044.8341x, R2 = 0.9958) in the range 101 cfu/mL to 105 cfu/mL, with a limit of detection (LOD) of 4 cfu/mL. This method was also used successfully to detect S. typhimurium inoculated into pork samples. This method, using aptamers and the SGNPs-based SERS biosensor may be useful to detect S. typhimurium for food safety analysis and clinical diagnosis.