Turn-Off Fluorescent Sensor Based on 3-Aminophenylboronic Acid-Modified CdSe/ZnS Quantum Dots for Specific Detection of γ-Hexachlorocyclohexane (Lindane)

Herein, a highly selective and sensitive fluorescent sensing system is developed for the accurate quantitative determination of γ-Hexachlorocyclohexane (γ-HCH, Lindane). With carboxyl-functionalized CdSe/ZnS core–shell quantum dots (QDs) as the substrate, 3-Aminophenylboronic acid (3-APBA) is covalently conjugated onto the quantum dot surface via an amidation reaction. Systematic characterizations are used to confirm the successful fabrication of the CdSe/ZnS-COOH@3-APBA fluorescent probe, which exhibits excellent luminescence properties and superior colloidal dispersion stability. Under optimal experimental conditions, an increased γ-HCH concentration induces gradual attenuation of the probe fluorescence intensity. A favorable linear correlation is achieved within 10–140 nM, and the limit of detection is 2.62 nM. Mechanistic studies reveal that γ-HCH binds to 3-APBA on the probe surface via halogen bonding to form non-fluorescent ground-state association complexes, thereby triggering static quenching of the probe. This method can effectively distinguish α-, β-, and δ-hexachlorocyclohexane isomers. With the merits of simple operation, high sensitivity, excellent stability, and strong anti-interference capability, it provides a new strategy for the rapid screening and accurate quantification of γ-HCH residues in environmental and food matrices.