Design and application of a highly selective and sensitive fluorescent probe for continuous detection of Cu²⁺ and GSH...

Optimal levels of Cu²⁺ are essential for the proper functioning of organisms, while excessive quantities lead to significant detrimental effects. In this study, a Schiff base fluorescent probe XSF based on 3-aminobenzo[b]thiophene-2-carboxylate was been successfully designed and synthesized. The synthesis pathway of XSF is highly convenient, enabling the detection of Cu²⁺ through a dual channel mechanism involving fluorescence quenching and colorimetric response. It exhibits exceptional sensitivity with an extremely low detection limit (2.91 × 10^-7 M), rapid response kinetics (less than 10 s), and applicability within a pH range of 3-9. The fluorescence quenching of XSF by Cu²⁺ was reasonably explained using techniques such as ¹H NMR and DFT calculations. In addition, satisfactory recovery rates were achieved in the detection of Cu²⁺ in actual samples such as drinking water, ginger, and chocolate. The visual detection method was successfully applied to real samples including cellophane noodles and towels, and XSF test papers were prepared, fully demonstrating the potential of XSF for practical testing applications. The XSF-Cu²⁺ system demonstrates high sensitivity in the detection of GSH (LOD = 8.73 × 10^-7 M) and exhibits a remarkable enhancement in fluorescence response. XSF has successfully demonstrated its application in the detection of Cu²⁺ and GSH within cells, thus highlighting its potential as a promising tool in the field of biology.