Self-Diffusion of a Semiflexible Polypeptide in a Magnetically Aligned Liquid Crystalline Phase

Abstract

The tracer self-diffusion coefficient of semiflexible poly(γ-benzyl-α,L-glutamate) with a length of ∼160 nm and a diameter of ∼1.6 nm is determined by fluorescence photobleaching recovery in the magnetically aligned liquid crystalline phase. The rate of diffusion in the direction of molecular alignment declines with concentration in the liquid crystalline phase, while the rate perpendicular to the direction of molecular alignment remains approximately constant. At concentrations just sufficient to sustain the liquid crystalline phase, the parallel diffusion exceeds the perpendicular diffusion by a factor of almost 5. This ratio declines to as little as 2 at higher concentrations. Comparisons are made with previous studies on other systems ranging from rigid virus particles to small mesogens.

Keywords:

• Polymer liquid crystal
• anisotropic diffusion
• semiflexible polypeptides

Acknowledgment

This material is based upon work supported by the National Science Foundation under Grants 0606117 and 1005707 (DMR).

Notes

Comprehensive information about pyridine (CAS Number 110-86-1) appears in The Beilstein Handbook (System Number 3051: vol 20, p. 181; 1st supplement, Vol. 20, p. 54; 2nd supplement, Vol. 20, p. 96, 4th supplement, Vol. 20, p. 2205).