Phone (Lab): 401-863-1405
email: jun_he@brown.edu

• Nanjing University (1997-2001) B.S.
• Nanjing University (2001-2004) M.S.

F-actin Network Dynamics

F-actin is a semi-flexible macromolecule. Above a few tenths of a percent in volume fraction, F-actin solution undergoes an isotropic (I) to nematic (N) phase transition. By tracking fluorescently labeled F-actin in a network of unlabeled filaments, we studied the diffusion behavior of F-actin across the I-N phase transition and found an abnormal slowdown of longitudinal diffusion after the system enters nematic phase. In contrast, for an ordinary liquid crystalline I-N phase transition, there is an abrupt increase of longitudinal diffusion coefficient at the transition point. We attribute this counter-intuitive phenomenon to counter ion condensation induced reduced repulsion or possible weak attraction between filaments.

• He, J., Viamontes, J., Tang, J. X.,
  Counterion-Induced Abnormal Slowdown of F-Actin Diffusion across the Isotropic-to-Nematic Phase Transition
  Phys. Rev. Lett. 99, 068103 (2007) (PDF)