A sensitive electrochemical immunosensor for the detection of squamous cell carcinoma antigen by using PtAu nanoparticles loaded on TiO2 colloidal spheres as labels

Abstract

A sensitive sandwich-type electrochemical immunosensor for detection of squamous cell carcinoma antigen (SCCA) was developed by using PtAu nanoparticles loaded on TiO₂ colloidal spheres (PtAu/TiO₂) as secondary-antibody (Ab₂) labels. In this work, nitrogen-doped graphene sheets (N-GS) and chitosan (CS) were applied to modify the glassy carbon electrode (GCE) surface. Then the SCCA primary antibody (Ab₁), SCCA and PtAu/TiO₂-Ab₂ were sequentially modified onto the electrode surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the preparation process of the immunosensor and the amperometric response of the immunosensor for catalyzing hydrogen peroxide (H₂O₂) reduction was also recorded. Under optimal conditions, the immunosensor exhibited a wide linear response to SCCA ranging from 0.001 ng mL⁻¹ to 15 ng mL⁻¹, with a low detection limit of 0.3 pg mL⁻¹. The proposed immunosensor displayed good reproducibility, high sensitivity, and acceptable stability. Therefore, this method has potential application for clinical immunoassays of other biomolecules.