Capture efficiency of Escherichia coli in fimbriae-mediated immunoimmobilization

Capturing pathogens on a sensor surface is one of the most important steps in the design of a biosensor. The efficiency of a biosensor at capturing pathogens has direct bearing on its sensitivity. In this work we investigated the capturing of Escherichia coli on substrates modified with antibodies targeting different types of fimbriae: K88ab (F4), K88ac (F4), K99 (F5), 987P (F6), F41, and CFA/I. The results suggest that all these fimbriae can be used for the efficient immobilization of living E. coli cells. The immobilization efficiency was affected by the purity and clone type of the antibody and the fimbriae expression level of the bacteria. For a specific fimbriae type, a higher immobilization efficiency was often observed with the monoclonal antibodies. Immunoimmobilization was utilized in an antibody microarray immersed in a mixed culture of pathogens to demonstrate the rapid and simultaneous label-free detection of multiple pathogens within less than 1 h using a single test. The capture rate of living pathogens exceeds a single bacterium per 100 × 100 μm(2) area per 0.5 h of incubation for a bulk concentration of 10(5) cfu/mL.