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Biophysical Society, Biophysical Journal, 1(110), p. 44-50

DOI: 10.1016/j.bpj.2015.11.028

Biophysical Society, Biophysical Journal, 2(111), p. 463

DOI: 10.1016/j.bpj.2016.07.007



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Optical Pushing: A Tool for Parallelized Biomolecule Manipulation

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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The ability to measure and manipulate single molecules has greatly advanced the field of biophysics. Yet, the addition of more single-molecule tools that enable one to measure in a parallel fashion is important to diversify the questions that can be addressed. Here we present optical pushing (OP), a single-molecule technique that is used to exert forces on many individual biomolecules tethered to microspheres using a single collimated laser beam. Forces ranging from a few femtoNewtons to several picoNewtons can be applied with a submillisecond response time. To determine forces exerted on the tethered particles by the laser, we analyzed their measured Brownian motion using, to our knowledge, a newly derived analytical model and numerical simulations. In the model, Brownian rotation of the microspheres is taken into account, which proved to be a critical component to correctly determine the applied forces. We used our OP technique to map the energy landscape of the protein-induced looping dynamics of DNA. OP can be used to apply loading rates in the range of 10(-4)-10(6) pN/s to many molecules at the same time, which makes it a tool suitable for dynamic force spectroscopy.