| Escherichia coli O157:H7 is one of highly harmful food-borne disease-caused bacteria, for the probability of epidemic outbreak and the danger of infection. It is in dire need of a rapid and accurate method for E.coli O157:H7 detection. This research investigated the mass response characteristic of QCM for detection of E.coli Ol 57: H7. Four different immobilization methods were used to immobilize the monoclonal antibody onto a 8MHz AT-cut quartz crystal's surface, and two analytical procedures namely dip-and-dry and flow injection methods were used to detect E.coli O157.H7. The binding of target bacteria onto the immobilized antibody decreased the sensor's resonant frequency, and the frequency shift was correlated to the bacterial concentration. The biosensor was characterized with high sensitivity, relatively rapid and reliable analysis.Main contents and results were as follows:Firstly, four types of antibody immobilization methods included silanized layer, MPA self-assembled monolayer (SAM), PEI polymer membrane and Protein A were applied in this study. And learned the frequency shift from chemical reaction on the electrode's surface by dip-and-dry and flow injection methods. The results showed that the Protein A-based antibody immobilization method and flow injection method offered the best ways to provide a sensitive fast and reproducible detection results.Secondly, the effects of concentration of protein A and antibody on the frequency shift were also discussed. The results showed that the best protein A concentration was 0.50mg/mL, and the best antibody concentration was 1.0mg/mL.Thirdly, the immunosensor could detect E.coli O157:H7 with a detection limit of 7.33×10~3CFU/mL, in a range of 7.33×10~3CFU/mL to 7.33×10~8CFU/mL. The system was quite specific to E.coli Ol57: H7 and applicable for repetitive use after a regeneration step employing NaOH, HC1 and Piranha reagent.
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