Development of a Capacitive Immunosensor for Detection of Escherichia coli O157:H7

Abstract

A sensitive immunosensor based on capacitive measurement was developed for rapid detection of Escherichia coli O157:H7. The immunosensor was established on a gold surface. Anti-E. coli O157:H7 antibodies were immobilized onto the gold surface through adsorption of self-assembled monolayers. The specific binding between E. coli O157:H7 cells and anti-E. coli O157:H7 antobodies resulted in capacitance changes which was directly detected by electrochemical instrument. The experimental results indicated that capacitance change was correlated with E. coli O157:H7 concentration. Using capacitance measurement, detection limit of 102 cfu/mL was obtained. A linear relationship range between the capacitance change and the logarithm of E. coli O157:H7 concentration was found. Cyclic voltammetry was also employed as a confirmation method to follow the stepwise assembly of the systems. This research demonstrated that the capacitive immunosenor had potential to be an alternative rapid and specific technology for the detection of pathogenic bacteria.