Optical detection of pathogens using protein chip

Optical detection method based protein chips for detection of the various pathogens such as Escherichia coli O157:H7, Salmonella typhimurium, Yersinia enterocolitica, and Legionella pneumophila in contaminated environment were developed. In order to endow the orientation of antibody molecules on solid surface, protein G was introduced. Gold (Au) surface was modified with 11-mercaptoundecanoic acid (11-MUA) and the protein G was immobilized on the Au surface. And the spots of different antibodies against pathogens (E. coli O157:H7, S. typhimurium, Y. enterocolitica, and L. pneumophila) on protein G of Au surface were arrayed using a microarrayer. The responses of the various pathogens such as E. coli O157:H7, S. typhimurium, Y. enterocolitica, and L. pneumophila to the protein chip was investigated by surface plasmon resonance (SPR), fluorescence microscopy and imaging ellipsometry (IE). The lowest detection limit of the fluorescence based protein chip was 10(2) CFU/mL and the protein chip using IE could successfully detect the pathogens in concentrations varying from 10(3) to 10(7) CFU/mL.