A programmable recirculating device for surface modification, antibody immobilization and bacteria detection of a QCM biosensor

Escherichia coli O157:H7 is one of the most dangerous foodborne pathogens causing serious illness. Rapid and sensitive methods are urgently needed for detecting this bacterium to ensure food safety. The objective of this research was to develop a recirculating device for surface modification, antibody immobilization and bacteria detection of quartz crystal microbalance (QCM) biosensor and evaluate it for detection of E. coli O157:H7. The QCM biosensor was fabricated by self-assembling of Protein A and affinity-purified anti-E. coli O157:H7 antibodies immobilized on the gold electrode. The device consisted of a peristaltic pump, two microelectric multi-position valves and tubings. The system was controlled by a laptop and could run automatically with the use of a developed software program. Compared to the static mode of conventional immobilization of Protein A and antibody, the device was able to recirculate the reagents through the QCM flow cell with optimum protocols under continuous flow mode condition. Cells of the target bacteria were introduced into the QCM flow cell and recirculated to be captured by the antibodies immobilized on the gold electrode. This dynamic method was proven more efficient for immobilization of Protein A and antibodies in terms of time, surface coverage, agent reuse, and consistency. The results of this study showed that this rescirculating device was effective in capture of E. coli O157:H7 cells from large volume of samples.;Key Word: E. coli O157:H7, recirculation, biosensor, bacteria detection...