Kathryn Simpson

Kathryn defended her PhD thesis in January, 2004. She now works as a medical writer for Medtronic Sofamor Danek. Her webpage while at Rice is provided below:

Quantification of Staphylococcal Adhesion Using Optical Tweezers
Biofilm formation, a common cause of medical device failure, initially results from bacterial adhesion to an adsorbed layer of extracellular matrix (ECM) proteins on the implant surface.  Molecules called microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) on the surface of bacterial cells mediate this adhesion.  Because an early step in biofilm development is the binding of bacteria to an adsorbed protein layer, developing a greater understanding of the interactions between MSCRAMMs and their ligands can lead to improved methods of preventing bacterial adhesion or removing adherent bacteria.  The objective of my project is to use optical tweezers to characterize various aspects of MSCRAMM-related staphylococcal adhesion to surfaces coated with extracellular matrix proteins. 

Optical tweezers, which are based on Maxwell's theory of radiation pressure, use a highly focused laser beam to exert force on microscopic objects.  To study bacterial adhesion, we use optical tweezers to detach bacterial cells from polymer microspheres coated with ECM proteins.  We can then determine the amount of force required for this detachment.  The process of adhesion and detachment is illustrated in the micrographs to the right.
Kathryn Simpson
The bacterium is trapped (A) and held against a coated microsphere for 10 seconds (B).  The trapping power is increased to initiate the detachment process (C), and finally the cell completely detaches from the microsphere (D).
Copyright ©2002
Photomedicine and Biomedical Photonics Lab
Maintained by Brian Pikkula   
 Last Update: July, 2002