FIG. 2.

H. pylori and E. coli O157:H7 antigen detection in PDMS microchannels with the RLS nanoparticles as the readout for the heterogeneous immunoassay. Bacterial protein lysates were passively adsorbed onto PDMS microchannels. Polyclonal biotinylated H. pylori and E. coli O157:H7 antibodies were used as primary antibodies (1° Abs), and a goat polyclonal antibiotin antibody-functionalized RLS nanoparticle was used as the secondary antibody. Dark-field microscopy was used for image acquisition. (A) H. pylori lysates were used as positive control antigens, while L. rhamnosus strain R011 and coating buffer alone were used as negative controls. The biotinylated anti-H. pylori antibody was used as a positive control primary antibody, while a nonbiotinylated anti-H. pylori antibody (DAKO) and normal rabbit IgG were used as negative controls. (B) E. coli O157:H7 lysates were used as positive control antigens, whereas L. rhamnosus R011 and coating buffer alone were used as negative controls. Biotinylated anti-E. coli O157:H7 antibody was used as a positive control primary antibody, while a nonbiotinylated anti-E. coli O157:H7 antibody (Kirkegaard & Perry Laboratories [KPL]) and goat serum were used as negative controls.