Point-of-care testing: a disposable label-free electrochemical CA125 and HE4 immunosensors for early detection of ovarian cancer.

Cancer antigen 125 (CA125) and human epididymal secretory protein 4 (HE4) are critical biomarkers for ovarian cancer diagnosis and progression monitoring; therefore, sensitive determination of their levels in body fluids is crucial. In recent study, label-free CA125 and HE4 immunosensors were prepared using disposable screen-printed carbon electrodes modified with reduced graphene oxide, polythionine, and gold nanoparticles for the sensitive, fast, and practical determination of CA125 and HE4. Differential pulse voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy methods were used for the electrochemical determination of antigens in four different linear ranges (1-100 pg mL, 0.01-10 ng mL, 10-50 ng mL and 50-500 ng mL). High sensitivity, low limit of detection, and limit of quantification were obtained for each linear range with a correlation coefficient above 0.99. The application stability of CA125 and HE4 immunosensors was determined as 60 days, and the storage stability was determined as 16 weeks. Immunosensors showed high selectivity in nine different antigen mixtures. The reusability of the immunosensors has been tested up to 9 cycles. The Risk of Ovarian Malignancy Algorithm score% values were calculated using the concentration of CA125 and HE4 in the blood serum and evaluated in terms of ovarian cancer risk. For the point-of-care testing, CA125 and HE4 levels at pg mL concentration were measured in blood serum samples using the developed immunosensors and a hand-held electrochemical reader in approximately 20-30 s, and high recoveries were obtained. These disposable label-free immunosensors are user-friendly and can be used in point-of-care tests for rapid and practical detection of CA125 and HE4 with high selectivity, sensitivity, and repeatability.