Auto-reduction of Au(III) on Fe-Doped, Pyrrolic-N-Modified nanoporous carbon derived from ZIF-8 for the electrochemical immunosensing of CA-125

Abstract

Ovarian cancer (OC) is associated with high late mortality owing to hidden symptoms in the early stages and limited screening measurements. Therefore, it is urgent to develop a highly efficient label-free immunosensor for targeting cancer antigens. In this study, we developed a gold-loaded iron-doped nanoporous carbon (denoted as Au@Fe-NC) as an ideal substrate for cancer antigen detection with high specificity and sensitivity. First, an Fe, N-doped nanoporous carbon (Fe-NC) material was synthesized by carbonizing a Fe-doped metal-organic framework at 900 °C under continuous nitrogen flow. The resultant Fe-NC contains pyrrolic-N, which facilitates the auto-reduction of Au3+ to Au⁰ without requiring an external reducing agent. Thus, the Au@Fe-NC was spontaneously formed by mixing an aqueous HAuCl₄ solution with Fe-NC. The immunosensor developed using Au@Fe-NC exhibits outstanding stability as well as high sensitivity to carbohydrate antigen 125 (CA-125), a tumor marker, presenting a linear dynamic range of 0.1 pg mL−1 to 1 µg mL−1 and a detection limit of 0.1 pg mL−1. The proposed Au@Fe-NC-based immunosensor has the ability to detect CA-125 in human serum samples and is a promising material for OC diagnosis.