Quantitative detection of chloramphenicol residue in fish based on SERS aptasensor coupled with magnetic separation

Chloramphenicol (CAP) is a widely used antibiotic in aquaculture. However, its improper use and the resulting residues in fish have become a significant concern for human health. Conventional methods for quantifying CAP are complex and expensive, leading to the need for more efficient and sensitive techniques. In this study, both CAP aptamer and sulfhydryl (SH) complementary DNA strand (SH-cDNA) were bound to gold and silver core–shell nanoparticles (Ag@Au CSNPs) and core–shell magnetic nanoparticles (Fe3O4@Au MNPs) via Au-S covalent bonding and were used as SERS signal probes and capture probes, respectively. The principle of aptamer competitive recognition was applied to achieve the quantitative detection of CAP in fish. The capture probe and the signal probe generated strong signals by complementary hybridization in the absence of CAP in the detection system. In the presence of CAP, the CAP aptamer bonded to the CAP, and the signal probe was separated from the capture probe, resulting in a linear decrease in SERS signal intensity. Consequently, there was a strong inverse relationship between SERS intensity and the logarithm of CAP concentration, ranging from 10-5 to 10-1 µg·mL−1 (R2 = 0.9974). The limit of detection (LOD) was as low as 16 pg·mL−1. The established method exhibited strong selectivity, anti-interference, reproducibility, and stability.