AFM, CLSM and EIS characterization of the immobilization of antibodies on indium–tin oxide electrode and their capture of Legionella pneumophila

The microscopic surface molecular structures and properties of monoclonal anti-Legionella pneumophila antibodies on an indium–tin oxide (ITO) electrode surface were studied to elaborate an electrochemical immunosensor for Legionella pneumophila detection. A monoclonal anti-Legionella pneumophila antibody (MAb) has been immobilized onto an ITO electrode via covalent chemical bonds between antibodies amino-group and the ring of (3-Glycidoxypropyl) trimethoxysilane (GPTMS). nctionalization of the immunosensor was characterized by atomic force microscopy (AFM), water contact angle measurement, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of [Fe(CN)6]3−/4− as a redox probe. Specific binding of Legionella pneumophila sgp 1 cells onto the antibody-modified ITO electrode was shown by confocal laser scanning microscopy (CLSM) imaging and EIS. AFM images evidenced the dense and relatively homogeneous morphology on the ITO surface. The formation of the complex epoxysilane-antibodies acting as barriers for the electron transfer between the electrode surface and the redox species in the solution induced a significant increase in the charge transfer resistance (Rct) compared to all the electric elements. ar relationship between the change in charge transfer resistance (ΔRct=Rct after immunoreactions – Rct control) and the logarithmic concentration value of L. pneumophila was observed in the range of 5×101–5×104 CFU mL−1 with a limit of detection 5×101 CFU mL−1. esent study has demonstrated the successful deposition of an anti-L. pneumophila antibodies on an indium–tin oxide surface, opening its subsequent use as immuno-captor for the specific detection of L. pneumophila in environmental samples.