An electrochemical immunosensor based on MXene-GQD/AuNPs for the detection of trace amounts of CA-125 as specific tracer of ovarian cancer.

An electrochemical immunoassay system was developed to detect CA-125 using a glassy carbon electrode (GCE) modified with MXene, graphene quantum dots (GQDs), and gold nanoparticles (AuNPs). The combined MXene-GQD/AuNPs modification displayed advantageous electrochemical properties due to the synergistic effects of MXene, GQDs, and AuNPs. The MXene-GQD composite in the modified layer provided strong mechanical properties and a large specific surface area. Furthermore, the presence of AuNPs significantly improved conductivity and facilitated the binding of anti-CA-125 on the modified GCE, thereby enhancing sensitivity. Various analytical techniques such as FE-SEM and EDS were utilized to investigate the structural and morphological characteristics as well as the elemental composition. The performance of the developed immunosensor was assessed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), square wave voltammetry (SWV), and differential pulse voltammetry (DPV). Under optimized conditions in a working potential range of -0.2 to 0.6 V (vs. Ag/AgCl), the sensitivity, linear range (LR), limit of detection (LOD), and correlation coefficient (R 2 ) were determined to be 315.250 µA pU.mL -1 /cm 2 , 0.1 to 1 nU/mL, 0.075 nU/mL, and 0.9855, respectively. The detection of CA-125 in real samples was investigated using the developed immunoassay platform, demonstrating satisfactory results including excellent selectivity and reproducibility.