High-performance electrochemical aptasensor for CA 125 based on CuNP-decorated reduced graphene oxide

This study presents the development of an electrochemical aptasensor for the detection of cancer antigen 125 (CA 125), an important biomarker for ovarian cancer. The aptasensor was developed based on a nanocomposite of copper nanoparticles (CuNPs) decorated on reduced graphene oxide (rGO) by direct current (DC) magnetron sputtering. This design enhances electron transfer and provides a large surface area for immobilization of the aptamer. The CA 125-specific aptamer was covalently conjugated to the modified electrode, allowing for selective and label-free detection. Differential pulse voltammetry was used to record the electrochemical signal. Oxidation of the CuNPs generates an electrochemical signal, while immobilization of the aptamer and subsequent incubation with CA 125 lead to a considerable decrease in this response. The variation in the oxidation peak current of CuNPs, observed with and without CA 125, serves as a reliable analytical signal for the quantification of CA 125 concentration. The proposed aptasensor demonstrates a wide linear concentration range (0.1-400.0 U mL^-1) for CA 125 detection, with a low detection limit of 1.6 × 10^-2 U mL^-1. Furthermore, the aptasensor exhibited excellent applicability in both patient and healthy human serum samples, making it a promising tool for early cancer diagnosis and point-of-care testing.