Immunosensor for detection of Legionella pneumophila based on imaging ellipsometry

An immunosensor based on imaging ellipsometry as detection method was developed for the detection of Legionella pneumophila. Sequential depositions of 11-mercaptoundecanoic acid (11-MUA), protein G, and the monoclonal antibody against L. pneumophila (Mab) on gold surface were confirmed via surface plasmon resonance (SPR). Also, the cross-sensitivity of the Mab against several pathogens including Escherichia coli O157:H7, Salmonella spp. and Yersinia spp. was investigated using the SPR. The immunosensor for detection of L. pneumophila was fabricated by injecting protein G solution using the micro-arrayer and immobilizing the Mab on it. Imaging ellipsometry was used for detection of binding of L. pneumophila to the Mab layer. Ellipsometric images of the protein spots on the substrate according to binding of L. pneumophila with various concentrations were acquired, and the mean optical intensities of them were calculated using the image process software. The low detection limit was about 103 CFU/ml.