Designing a Capacitive Immunosensor for Detection of Hepatitis B Surface Antigen

摘要

A capacitive immunosensor for monitoring capacitance changes due to hepatitis B surface antigen (HBsAg) was designed. There are three factors affecting capacitive biosensors: surface area, distance between the capacitor electrodes and dielectric constant of the material between the electrodes. Our results indicate that the presence of HBsAg mostly affects the surface area of the capacitors and causes an increase in the capacitance. This method is simple, fast, low-cost, and the experiments were devoted to improvement of its accuracy and limit of detection. The results were achieved by developing a sandwich type immunoassay capacitor by using gold nanoparticles as amplifiers. The experiments were also conducted on accuracy enhancement by monitoring each step of the immunochemical reactions in real-time with new advanced optical methods and by using different designs of electrodes and magnetic nanoparticles.