An electrochemiluminescence immunosensor with double co-reaction accelerators based on Ag3PO4@EuPO4-AgNP for detecting squamous cell carcinoma antigen

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 (Ag 3 PO 4 ) nanoparticles were modified on the surface of EuPO 4 nanowires to improve their poor dispersibility/solubility. At the same time, EuPO 4 was used as a co-reaction accelerator to catalyze S 2 O 8 2− to produce more intermediates (SO 4 •− ), significantly enhancing the ECL signal of Ag 3 PO 4 . Ag nanoparticles (AgNP) modified on Ag 3 PO 4 @EuPO 4 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. Graphical Abstract