Electrochemiluminescence sensor based on Ag/ZnO nanomaterial-enhanced GPTMS/FeCdS@FeInS for sensitive analysis of CD44.

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@FeInS 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@FeInS/KSO system through efficient generation of SO˙ 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 SO, generating more SO˙, which enhanced the ECL intensity and stability of GPTMS/FeCdS@FeInS under the dual influence of catalysing SO 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 to 100 ng mL and a detection limit of 9.16 fg mL.