A novel DNA quantum dots/aptamer-modified gold nanoparticles probe for detection of Salmonella typhimurium by fluorescent immunoassay

A novel self-assembled core-shell structure fluorescent probe (DNA-QDs/AuNPs, DQA) was constructed for the first time by integrating gold nanoparticles (AuNPs) and DNA quantum dots (DNA-QDs), which can combine with the immunomagnetic separation (IMS) to test for the levels of Salmonella typhimurium (S. typhi). Based on the polyethyleneimine (PEI)-coated AuNPs, the DQA probe can simplify the tedious process of modifying the probe by aptamers and amplify the fluorescence signal by electrostatic adsorption of a large amount of DNA-QDs. The S. typhi can be successfully detected with a broad range from 10 cfu mL−1 to 1.0 × 107 cfu mL-1 with the limit detection (LOD) of 13.6 cfu mL−1. Moreover, the obtained DQA probe exhibits high specificity and stability detection. Due to the convenient and rapid synthesis of the DQA probe, it will be suitable for ordinary technicians in the detecting of S. typhi conveniently and effectively.