Synthesis of AgInS₂ quantum dots for metronidazole detection in eggs using a fluorescence-quenched probe

Metronidazole (MNZ) is a type of nitroimidazole antibiotic widely used in livestock feed. The extensive use, overuse, and misuse of MNZ have resulted in high levels of MNZ residues in animal products, posing serious health risks to people. Based on the effective fluorescence quenching capability of MNZ, a highly precise technique characterized by low-cost materials, low detection limit, and simple operational procedure was established to detect MNZ in eggs by modulating the fluorescence produced by AgInS₂ quantum dots (AIS QDs). The performance of the prepared sample was outstanding as the linear range was 0.25–80.00 μg/mL with a detection limit (LOD) of 0.166 μg/mL and R² = 0.9996, having an average recovery of MNZ in egg white ranged from 94.88 % to 102.39 %. This detection method has the advantages of a wide detection range, high sensitivity, high accuracy, excellent selectivity, and simple operability, and it can be used to detect MNZ in eggs after further study. The fluorescence quenching mechanism of AIS QDs by MNZ is speculated as a dynamic quenching mechanism of light-induced electron transfer.