Research

The Valentine Research Group employs state-of-the-art nanoscale manipulation and measurement techniques to probe diverse biological materials on length scales from that of single proteins (a few nanometers) to that of entire cells (~ 100 microns or more). This highly interdisciplinary work lies at the intersection of engineering, physics, biology and chemistry.

Our primary interest lies in understanding how forces are generated and transmitted in living materials, and how these forces control cellular outcomes. Understanding the mechanical properties of the cytoskeleton, a dynamic protein polymer network that forms the foundation of cellular architecture, is essential to this goal. The cytoskeleton gives cells strength, while enabling them to crawl, change shape and divide, and it forms the tracks upon which force-generating motor proteins move.

To investigate the biophysical and biochemical basis of cellular mechanics, we use a wide variety of experimental techniques, including: high-precision optical trapping to probe single molecules of motor and crosslinking proteins; micromechanical manipulation of cytoskeletal networks that are reconstituted from purified components or assembled in cell extracts; and advanced fluorescence imaging of the self-assembly of large protein complexes. 

To extend this work to cells and tissues, we have developed a suite of high-force, low-cost magnetic tweezers devices that enable precise manipulation of living materials and are compatible with a wide range of imaging modalities. We are also developing novel methods of measuring interaction and deformation forces within living cells, and are developing new classes of man-made materials that capture the extraordinary properties of living systems, including the ability to respond to stimuli, move, and heal.