Gap-enhance Raman tags (GERTs) competitive immunoassay based Raman imaging for the quantitative detection of trace florfenicol in milk

Surface Enhanced Raman Spectroscopy (SERS) is a highly sensitive detection method, however, it is still challenging to directly detect florfenicol due to its low Raman activity. To solve this problem, we present a novel sensor for selective detection of florfenicol residue in milk using gap-enhance Raman tags (GERTs) competitive immunoassay. In this nanosensor, Raman reporters 4-mercaptobenzoic acid (4MBA) were embedded in the 1 nm gap of Au core-gap-Au shell nanoparticles, which can protect 4MBA molecules from unwanted external environments and provide a high enhancement. The parameters affecting the detection sensitivity were discussed and optimized. The limit detection of florfenicol in milk can reach 0.1 μg/kg. To evaluate the performance of GERTs immunoassay, [email protected] tags immunoassay was conducted and the results were compared. Moreover, Raman mapping was investigated to improve the quantitative prediction model with R 2 of 0.981 achieved, by eliminating the signal fluctuations caused by the inhomogeneous distribution of GERTs.