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Abstract
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). The functionalization 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. A linear 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 × 10(1)-5 × 10(4) CFU mL(-1) with a limit of detection 5 × 10(1)CFU
mL(-1). The present 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.