Orientation of semiflexible biopolymers in a magnetic field

A theory is presented to explain the stretching and orientation of a semifl exible chain such as the biopolymeric filamentous actin and deoxyribonuclei c acid in a magnetic field. Both dilute and concentrated solutions are cons idered. The theory predicts the requirement of a high magnetic field to ach ieve a high degree of orientation in a dilute solution. The experimental va lue of the order parameter for a dilute, polydisperse F-actin solution has been compared with the theoretical value. On the other hand, a molecular fi eld (nematic liquid crystal) which exists in a concentrated solution can ac hieve the same effects of stretching and orientation and can be assisted by a magnetic field. Sources of diamagnetic anisotropy in biopolymers have be en cited, (C) 2000 John Wiley & Sons, Inc.