Label-Free Electrochemical Immunosensor Based on One-Step\nElectrochemical Deposition of AuNP-RGO Nanocomposites for Detection\nof Endometriosis Marker CA 125

Endometriosis\nis the third most prominent gynecological disorder.\nCancer antigen 125 (CA 125) is the primary serum marker used for late-stage\nendometriosis diagnosis and management. Herein, we developed a label-free\nimmunosensor for electrochemical detection of CA 125 for endometriosis\nblood serum samples. The sensor was fabricated by one-step electrochemical\ndeposition of highly conductive gold nanoparticles (AuNPs) and reduced\ngraphene oxide (RGO) nanocomposite, via one-step electrochemical deposition.\nThis method involved in situ reduction of HAuCl3 and graphene\noxide and increased electrocatalytic performance. Different analytical\ntechniques confirmed the morphology and structure of the AuNP/RGO\nnanocomposite. In addition, the antibody (Ab) was immobilized on the\nmodified electrode surface through the self-assembly monolayer. The\nsquare wave voltammetry method has been utilized to measure the interaction\nof Ab and antigen (Ag). The as-fabricated sensor demonstrates a dynamic\nlinear range of 0.0001 → 300 U mL–1 and lower\nlimit of detection is 0.000042 U mL–1 toward CA125\ndetection. The developed sensor provides acceptable stability, high\nselectivity, and reproducibility. The proposed immunosensor has been\napplied to the CA 125 detection in endometriosis patient blood samples,\nand the results confirm the reliability of the as-fabricated sensor\nthat is further associated with the standard ELISA analysis. The AuNP/RGO-based\nsensor can be used as an excellent tool for future prospective clinical\ndiagnostics applications.