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Proceedings Paper

Conformational mechanics of stimulus-responsive polypeptides
Author(s): Alexei Valiaev; Robert L. Clark; Ashutosh Chilkoti; Stefan Zauscher
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Paper Abstract

Stimulus-responsive polymers and polypeptides (SRPs) experience a significant entropic response when exposed to an environemental stimulus, such as a change in temperature. This phase transition directly affects polymer conformation and can potentially be harnessed for force generation in actuation devices on nano- and micro-scales. While interfacial applications of SRPs have been prototypically demonstrated, a systematic investigation of the phase transition behavior at the solid-liquid interface and on the single-molecule level is lacking. In this paper we present results from force-spectroscopy measurements probing the force-extension and conformational behavior of one SRP, elastin-like polypeptides (ELP), below and above their transition temperature. The results indicate that there is no signficant difference in the force extension behavior at intermediate and large extensions, but the behavior is dramatically different at small extensions. Results also demonstrated that above the phase transition temperature large, unspecific adhesion forces often gave way to constant force steps upon extension, indicating a collapsed, potentially entangled, hydrophobic state of the ELP. The extension behavior below the phase transition temperature, however, closely followed that of random polymer coil, without any significant unspecific adhesion forces. The excellent fit of a simple extended freely jointed chain model to the data at intermediate and large extension suggests that the ELP is in a random conformational state without significant secondary structure. Forces associated with a phase transition therefore arise likely from entropic conformational changes associated with a hydrophobic collapse.

Paper Details

Date Published: 13 August 2003
PDF: 10 pages
Proc. SPIE 5053, Smart Structures and Materials 2003: Active Materials: Behavior and Mechanics, (13 August 2003); doi: 10.1117/12.484700
Show Author Affiliations
Alexei Valiaev, Duke Univ. (United States)
Robert L. Clark, Duke Univ. (United States)
Ctr. for Biologically Inspired Materials and Materials Systems (United States)
Ashutosh Chilkoti, Duke Univ. (United States)
Ctr. for Biologically Inspired Materials and Materials Systems (United States)
Stefan Zauscher, Duke Univ. (United States)
Ctr. for Biologically Inspired Materials and Materials Systems (United States)


Published in SPIE Proceedings Vol. 5053:
Smart Structures and Materials 2003: Active Materials: Behavior and Mechanics
Dimitris C. Lagoudas, Editor(s)

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