Stretching a macromolecule in an atomic force microscope: statistical mechanical analysis.
We formulate the proper statistical mechanics to describe the stretching of a macromolecule under a force provided by the cantilever of an atomic force microscope. In the limit of a soft cantilever the generalized ensemble of the coupled molecule/cantilever system reduces to the Gibbs ensemble for an isolated molecule subject to a constant force in which the extension is fluctuating. For a stiff cantilever we obtain the Helmholtz ensemble for an isolated molecule held at a fixed extension with the force fluctuating. Numerical examples are given for poly (ethylene glycol) chains.
Kreuzer
H J
HJ
Department of Physics, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5.
Payne
S H
SH
D055592:Biophysical Phenomena; D001703:Biophysics; D046911:Macromolecular Substances; D018625:Microscopy, Atomic Force / Q000379:methods*; D015233:Models, Statistical; D008962:Models, Theoretical; D013223:Statistics as Topic
D046911:Macromolecular Substances