NFC-enabling smartphone-based portable amperometric immunosensor for hepatitis B virus detection

[Display omitted] •A smartphone-based electrochemical system operated via Near Field Communication (NFC) was developed for real-time monitoring of Hepatitis B Virus (HBV).•A simple label-free immunoassay was constructed by a portable card-sized electrochemical NFC tag sensor.•The system was able to detect clinically-relevant levels of HBsAg and was validated by standard laboratory tests. A smartphone-controlled electrochemical sensor operated entirely via Near Field Communication (NFC) was used to create a simple label-free immunoassay for detecting Hepatitis B Virus (HBV). The completed system was composed of a card-sized electrochemical NFC tag sensor integrated with a smartphone and antibody-modified electrode sensor. Screen-printed graphene electrodes (SPGE) were modified with gold nanoparticles, increasing high sensitivity while β-cyclodextrin (β-CD) was electropolymerized on the surface to capture antibodies. The modification and immobilization processes were verified by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The NFC-based electrochemical immunosensor was then used to quantify Hepatitis B surface antigen (HBsAg) using amperometric detection by measuring the current from the (Fe(CN)6)3−/4− redox couple before and after addition of HBsAg. The linear calibration curve and limit of detection for HBsAg were found to be 10−200 μg/mL and 0.17 μg/mL, respectively. The sensor was then tested with chronic HBV infected serum samples and the system showed a good correlation with traditional immunoassays. This electrochemical immunosensor has the potential to be an alternative platform for portable, simple, sensitive and selective tools that can readily assess a variety of health indicators using a low-cost sensor system operated from a smartphone.