Abstract

Single-molecule studies are revolutionizing broad areas of science in general and the studies of molecular motors in particular. The pioneering experiments with optical traps focused on the traditional motors myosin and kinesin, which have step sizes of 8 and 5 nm, respectively. Traditionally, optical-trapping experiments have been limited to net motions greater than 1 nm. Yet, a variety of important biological motions occur on even smaller distance scales. In particular, DNA-based molecular motors take steps as small as 0.34 nm or 1 base pair (bp). In the last few years, a number of key technical advances have improved the resolution of optical traps to 0.1 nm. These advances include use of He as a buffer gas to reduce laser pointing noise, dual-beam optical-trapping assays to decouple the assays from mechanical perturbations, novel trapping geometries to improve mechanical sensitivity, and differential detection to increase spatio -temporal resolution. These technical advances along with their biological applications will be highlighted. I will conclude with recent advances in active reduction of laser noise and mechanical vibration that bring base-pair resolution (and increased force precision) to the most widely used single- molecule assays, those coupled to surfaces.

© 2009 IEEE