Dendrimer supported electrochemical immunosensor for the detection of cholera toxin in water

Generation 2 poly (propylene imine) dendrimer (PPI) and gold nanoparticles (AuNP) were electro-co-deposited on a glassy carbon electrode and used as a platform for the development of an electrochemical immunosensor for the detection of cholera toxin in water. The immunosensor was prepared by the immobilisation of a probe anti-cholera toxin on a PPI-AuNP composite modified carbon electrode for 2 h at 38 °C and subsequently blocked by bovine serum albumin (BSA) to minimize nonspecific binding. Square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) were used for the interrogation of the immunosensor at each stage of preparation. The biosensor was responsive to the toxin over a concentration range of 10^-7 g mL^-1 to 10^-12 g mL^-1 and their SWV and EIS were used to plot the calibration curve with a correlation of 0.9945 for SWV and 0.9966 for EIS. A detection limit of 7.2x10^-13 g mL^-1 and 4.2x10^-13 g mL^-1 were calculated from the square wave voltammetric and electrochemical impedance spectroscopy measurement respectively. The biosensor exhibited good stability over a period of seven days when stored at 4 °C temperature.