Electrochemical Detection of Hg(II) Using EASA-Derived Glutathione-Modified Mesoporous Silica Films

Mercury contamination threatens aquatic ecosystems and human health because of its toxicity, persistence, and potential for bioaccumulation. This study investigated an electrochemically assisted self-assembly (EASA)-derived glutathione-modified thiol-functionalized mesoporous silica film on a fluorine-doped tin oxide (FTO) electrode as a proof-of-concept interface for Hg(II) detection. Films containing 5–15 mol% (3-mercaptopropyl)trimethoxysilane (MPTMS) were evaluated using charged redox probes, and the 10 mol% composition produced the highest electrochemical response. FTIR analysis supported silica-network formation and the retention of glutathione-associated functional groups. Under the selected conditions of pH 5.0, a deposition potential of −0.70 V, and a deposition time of 5 min, the MSF-GSH/FTO electrode exhibited a linear response from 5 to 60 µM Hg(II), with an estimated calibration-based detection limit of 4.27 µM. Resolved oxidation peaks were observed for Hg, Pb, and Cd in a mixed-metal solution. The interface combines direct EASA film formation, thiol incorporation, and post-deposition glutathione modification; however, further sensitivity improvement, replication, stability testing, and real-sample validation are required.