Molecularly imprinted electrochemical sensor for the point-of-care detection of a breast cancer biomarker (CA 15-3)

•Construction of an electrochemical sensor for breast cancer monitoring.•Preparation of a molecularly imprinted polymer selective to CA 15-3 protein.•The sensor is simple to fabricate, easy to operate and shows good performance. The incidence of breast cancer has been increasing over the years. To control and monitor this disease several tumor biomarkers have been proposed for early diagnosis, patient follow-up and/or treatment guidance. The only serum breast cancer biomarker in current use is the cancer antigen 15-3 (CA 15-3). In this work a molecularly imprinted polymer (MIP)-based electrochemical (voltammetric) sensor to monitor breast cancer was developed, based on direct surface imprinting of CA 15-3 on a screen-printed gold electrode (Au-SPE). The imprinting was performed in two steps: (1) adsorption of CA 15-3 on the surface of the Au-SPE and (2) electropolymerization of 2-aminophenol around the adsorbed protein. After extraction of the imprinted protein voltammetric analysis was conducted using hexacyanoferrate(II/III) as redox probe, measuring the signals before and after protein binding. The sensor was characterized by voltammetric techniques and electrochemical impedance spectroscopy, and the analytical responses of imprinted and non-imprinted polymer sensors were studied. A linear relationship between the peak current intensity of the redox probe and the logarithm of CA 15-3 concentration was established between 5 and 50UmL−1, achieving a limit of detection of 1.5UmL−1. The prepared MIP-sensor provides fast (15min) analysis and is cheap, easy to prepare, disposable and could easily be integrated in small portable point-of care devices.