In collaboration with the Whitesides group in the chemistry department we intend to investigate E. coli adhesion to man-made surfaces. In particulary, we intend to investigate the adhesion with a self-assembled monlayer (SAM) presenting mannose groups. This is a good model system by which to study polyvalency, and the general area is important because bacterial adherence to surfaces in contact with biological fluids is a persistent problem in medicine. For example, prosthetics and cathers inserted into patients are often sites of bacterial infection, leading to infection and eventual sepcisemia. Studying the basis behind bacterial adhesion will help understand how to deal with this problem, and perhaps polyvalent inhibitors might be an effective tool. Our work in this are may include a collaboratin with Warren Shaw at the Harvard Medical School. We would like to get E. coli (attenuated strains) which display type I fimbriae on their surface which recognize mannose.

In order to measure the adhesion, we intend to use optical tweezers to trap E.coli. The tweezers can then be used to control the collision between the E. coli and a SAM coated surface. The strength of the adhesion can be measured by finding the minimum optical tweezer depth that is sufficient to pull the E. coli away from the surface. The velocity and duration of the collision can be controlled via the tweezers.

In a separate series of experiments that would also involve a collaboration wtih the Whitesides group, we intend to use microfabricated optical waveguides to sort and manipulate cells confined in a microfluidic network.