Preparation and application on a kind of immobilization method of anti-diphtheria for potentiometric immunosensor modified colloidal Au and polyvinyl butyral as matrixes

In this paper, two technologies named as the self-assembled technique and the opposite-charged adsorption are combined for a novel immobilization of diphtheria antibody (anti-Diph) molecules applied to an immunosensor for detecting diphtheria antigen (Diph). Anti-Diph was immobilized successfully on nanometer-sized Au colloid particles associated with polyvinyl butyral on a platinum electrode surface, and was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized anti-diphtheria was shown to keep its biological activity well and exhibited direct electrochemical behavior toward Diph. The factors influencing the performance of the resulting immunosensor were studied in detail. The resulting immunosensor exhibited fast potentiometric response (<3 min) and the linear range was from 24 to 1280 ng mL−1 with a detection limit of 7.8 ng mL−1. Moreover, the studied immunosensor exhibited high sensitivity and long-term stability. The response mechanism of immuosensors was also preliminarily studied using AC impedance.