Iran Researchers Produce New Biosensor To Detect Hepatitis B

Tehran, May 14, IRNA - Tehran University researchers have produced an immunosensor for detecting hepatitis B surface antigen. Hedayatollah Qourchian, a member of the Institute of Biochemistry and Biophysics affiliated with the university, said a simple, rapid and label-free capacitive based immuno-biosensor was developed for detecting hepatitis B surface antigen (HBsAg). Two planar gold electrodes were used as capacitor plates. The surfaces of the electrodes were covered by an insulating molecular layer. Then, the primary anti-HBsAg was immobilized on the insulating layer. After the addition of HBsAg, the distance between the plates and also the average surface area of the plates changed. The alteration of these factors led to a change in capacitance that could be used as an indicator of the antibody–antigen interaction. In order to improve the sensitivity of the method, gold nanoparticles were attached to a secondary antibody. Due to the relatively large size of the particles, the thickness of the dielectric layer and capacitance changed remarkably. Therefore, the detection limit was improved to about 10 ng ml−1. Hepatitis B is an infectious illness of the liver caused by the hepatitis B virus that affects hominoidea, including humans. The virus is transmitted by exposure to infectious blood, while viral DNA has been detected in the saliva, tears, and urine of chronic carriers.