Electrochemiluminescence sensor based on Ag/ZnO nanomaterial-enhanced GPTMS/FeCdS@FeIn₂S₄ for sensitive analysis of...

Incorporating an additional metal ion into binary metal sulfides to adjust the band gap and carrier mobility, thereby forming ternary metal sulfides, has significant potential in the field of electrochemical luminescence. This research represents the first application of FeCdS@FeIn₂S₄ as an innovative electrochemiluminescence (ECL) emitter. To further enhance the ECL signal, ZIF-8-derived Ag-doped ZnO nanocomposites were engineered as co-reaction accelerators, leveraging their exceptional catalytic activity to enhance the FeCdS@FeIn₂S₄/K₂S₂O₈ system through efficient generation of SO₄˙^- radicals. A novel sandwich-type ECL immunosensor for detecting cell adhesion molecule 44 (CD44) was initially constructed. The biocompatibility of the material was enhanced through epoxy functionalization using 3-glycidyloxypropyltrimethoxysilane (GPTMS). Ag/ZnO served as a catalyst to promote the reduction of S₂O₈^2-, generating more SO₄˙^-, which enhanced the ECL intensity and stability of GPTMS/FeCdS@FeIn₂S₄ under the dual influence of catalysing S₂O₈^2- decomposition and acting as an energy donor. Through the synergistic catalytic effect of Ag, the electrical conductivity and biocompatibility of the composites were enhanced, and the bandgap width of ZnO was reduced, thereby improving the electron transfer capability of Ag/ZnO. The developed immunosensor was utilized to accurately detect CD44, exhibiting a linear range of 10 fg mL^-1 to 100 ng mL^-1 and a detection limit of 9.16 fg mL^-1.