Ultrasensitive bioassay of epitope of Mucin-16 protein (CA 125) in human plasma samples using a novel immunoassay based on silver conductive nano-ink: A new platform in early stage diagnosis of ovarian cancer and efficient management

Abstract Ovarian cancer (OC) is known to be one of the most lethal malignancies associated with women disease. The CA-125 protein is a repetitive epitope of MUC-16, which plays key role in enhancing the proliferation of cancer cells and inhibiting anticancer immune responses. It is the most widely used biomarker for early stage diagnosis of OC. Also it is the only serum marker which currently used in clinical diagnosis. Monitoring of CA-125 protein in the serum sample is also valuable in evaluating the response of ovarian cancer to treatment. In this research, a novel immunoassay based on immobilization of CA-125 antibody on the biointerface of silver nanoparticles modified graphene quantum dots ink (Ag NPs-GQDs) was successfully designed to recognition of CA-125 protein in a human plasma sample. The supplied immunoassay presents the proper ability to detect and determine the amount of CA-125 biomarker in low concentrations of CA-125 biomarker. The proposed immunosensor was employed for the detection of CA-125 using differential pulse voltammetry (DPVs) and square wave voltammetry (SWVs) techniques. The proposed interface leads to enhancement of accessible surface area for immobilizing a high amount of anti-CA-125 antibody, increasing electrical conductivity, boosting stability, catalytic properties and biocompatibility. Under the optimized operating conditions, the low limit of quantitation (LLOQ) for the proposed immunosensor was recorded as 0.01 U/ml, which this evaluation was performed at highly linear range of 0.01–400 U/ml. The proposed immunoassay was successfully applied for the monitoring of CA-125 in unprocessed human plasma samples.