Origin of nanomechanical cantilever motion generated from biomolecular interactions

Origin of nanomechanical cantilever motion generated from biomolecular interactions

^*Department of Mechanical Engineering, University of California, Berkeley, CA 94720; ^†Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831; ^‡Department of Pathology, University of Southern California, Los Angeles, CA 90033; and ^§Departments of Chemical Engineering and Chemistry, Materials Science Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720

Edited by Calvin F. Quate, Stanford University, Stanford, CA, and approved November 27, 2000 (received for review August 1, 2000)

Abstract

Generation of nanomechanical cantilever motion from biomolecular interactions can have wide applications, ranging from high-throughput biomolecular detection to bioactuation. Although it has been suggested that such motion is caused by changes in surface stress of a cantilever beam, the origin of the surface-stress change has so far not been elucidated. By using DNA hybridization experiments, we show that the origin of motion lies in the interplay between changes in configurational entropy and intermolecular energetics induced by specific biomolecular interactions. By controlling entropy change during DNA hybridization, the direction of cantilever motion can be manipulated. These thermodynamic principles were also used to explain the origin of motion generated from protein–ligand binding.

Footnotes

↵ ¶ To whom reprint requests should be addressed. E-mail: majumdar{at}me.berkeley.edu.
This paper was submitted directly (Track II) to the PNAS office.
Article published online before print: Proc. Natl. Acad. Sci. USA, 10.1073/pnas.031362498.
Article and publication date are at www.pnas.org/cgi/doi/10.1073/pnas.031362498
Abbreviation:

ssDNA,

single-stranded DNA