Development of a multiplex immunochromatographic strip test and ultrasensitive electrochemical immunosensor for...

This research proposes two methods for hepatitis B diagnosis including rapid testing and electrochemical assay. For the first method, a multiplex hepatitis B test strip was fabricated to serve as a rapid test for hepatitis B screening. It was developed to simultaneously test three essential serological markers of hepatitis B virus infection including hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (Anti-HBs) and hepatitis B core antibody (Anti-HBc). Gold nanoparticles (GNPs) were used as the signal generator on the test strip. Furthermore, a part of a paper network was incorporated on the strip for the gold-silver enhancement process. This paper network helped in decreasing the analysis time of enhancement and makes the enhancement process easier for rapid testing. The developed test strip was specific for each serological marker. The detection limits of HBsAg, Anti-HBs and Anti-HBc were obtained at 0.5, 0.3 and 0.1 μg mL^-1, respectively. For the second method, electrochemical impedance spectroscopy (EIS) was applied for HBsAg detection. This method was proposed for quantitative hepatitis B detection. Anti-HBs antibodies were immobilized on a carbon screen printed electrode (SPCE) via the N-ethyl-N'-(3-(dimethylamino)propyl)carbo-diimide/N-hydroxy succinimide (EDC/NHS) couple reaction which reacted with the carboxyl group of the BSA cross-linked film on the electrode. The electrode modification process was characterized by EIS. A linear relationship between delta charge transfer resistance (ΔRct) and HBsAg concentration was obtained in the range of 5-3000 ng mL^-1 with a detection limit of 2.1 ng mL^-1. This work is appropriate for quantitative analysis because it is a simple and low-cost method to implement as the SPCE is disposable. Therefore, we hope that this research will be useful to improve hepatitis B detection in the future.