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Bacteria chose to stick or not based on mechanical stiffness

The above images show bacteria colonies on thin film coatings of vastly different mechanical stiffness. The mechanical stiffness increases by about two orders of magnitude in the following order: blue-to-yellow-to-red (color added for effect). For the least stiff coatings (blue), a significant reduction in colony density was observed. Out of many possible factors, only mechanical stiffness was found to correlate positively with changing colony density.

Hospital and community acquired bacterial infections continue to be a major health concern around the world. As a result, there is a clear need for better bacteria-resistant coatings that can be easily applied to a range of medical devices, implants and other surfaces to control and, if possible, prevent microbe accumulation. Unfortunately, many of the critical factors controlling the attachment and spreading of bacteria on surfaces are not well understood.

The Rubner and Van Vliet groups of the MIT MRSEC have discovered a previously overlooked factor that should be considered in the design of anti-bacterial coatings. They have found that the mechanical stiffness of a hydrated thin film coating can be manipulated to reduce significantly the number of bacteria colonies attached to a surface. This new understanding, coupled with existing strategies for creating anti-microbial coatings could provide a powerful new weapon against these often deadly infections.

This work is a result of a collaboration enabled by a seed grant within the MRSEC program.

The research was primarily funded by the NSF MRSEC Program (award DMR-02-13282).

Substrata Mechanical Stiffness Can Regulate Adhesion of Viable Bacteria
J.A. Lichter, M.T. Thompson, M. Delgadillo, T. Nishikawa, M.F. Rubner, and K.J. Van Vliet, Biomacromolecules 9, 1571, 2008.

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