Development of a novel electrokinetically driven microfluidic immunoassay for the detection of Helicobacter pylori

A novel microchip-based electrokinetically driven immunoassay was developed in this study. The microchip was made of poly(dimethylsiloxane) (PDMS)/glass using photolithography and replica molding. The immunoreaction was between the anti-Helicobacter pylori antibody and the bacterial protein antigen immobilized on the wall of the microchannel. The conditions for antigen immobilization were optimized by adjusting the plasma treatment time. By varying the concentration of blocking buffer, a buffer containing 5% (w/v) bovine serum albumin (BSA) was shown to effectively minimize non-specific binding. Rhodamine-labeled secondary antibody was employed for signal generation. The dependence of the fluorescence signal on the concentrations of both the coating antigen and the primary antibody was obtained. The detection limits for both the coating antigen and the primary antibody are 1 ng/μL. The immunoassay only took 30 min when used to detect antibody. The microchips could be prepared and stored at 4 °C for at least 10 days before the immunoassay was performed. With further development on automatic control and detection strategy, this microfluidic immunoassay technique has a potential for point-of-care analysis.