An electrochemiluminescence immunosensor with double co-reaction accelerators based on Ag₃PO₄@EuPO₄-AgNP for...

This study aimed to design a sandwich electrochemiluminescence (ECL) immunosensor with double co-reaction accelerators for sensitively detecting squamous cell carcinoma antigen (SCCA). First, silver orthophosphate (Ag₃PO₄) nanoparticles were modified on the surface of EuPO₄ nanowires to improve their poor dispersibility/solubility. At the same time, EuPO₄ was used as a co-reaction accelerator to catalyze S₂O₈^2- to produce more intermediates (SO₄^•-), significantly enhancing the ECL signal of Ag₃PO₄. Ag nanoparticles (AgNP) modified on Ag₃PO₄@EuPO₄ composite nanomaterials were used not only as linkers of luminescence groups and biomarkers but also as a co-reaction accelerator to effectively enhance ECL signal. The designed ECL immunosensor displayed several advantages, including good stability and reproducibility. Under the optimal conditions, its linear range in detecting SCCA was 0.0001-50 ng·mL^-1, the detection limit was 25 fg·mL^-1 (S/N = 3), the recovery was 96.6-100.4%, and the relative standard deviation was less than 4.8%. It was successfully applied to detect SCCA in human serum.