%0 Journal Article %1 axial %A Mack, A H %A Schlingman, D J %A Regan, L %A Mochrie, S G %D 2012 %J Rev Sci Instrum %K phage %N 10 %P 103106-103106 %R 10.1063/1.4757862 %T Practical axial optical trapping %U http://www.ncbi.nlm.nih.gov/pubmed/23126750 %V 83 %X We describe a new method for calibrating optical trapping measurements in which tension is applied in the direction of the laser beam to a molecule tethered between a surface and an optically trapped bead. Specifically, we present a generally-applicable procedure for converting from the measured scattering intensity and the measured stage displacement to applied tension and bead-coverslip separation, using measurements of the light intensity scattered from an untethered, trapped bead. Our calibration accounts for a number of effects, including aberrations and the interference of forward-reflected bead-scattered light with the trapping beam. To demonstrate the accuracy of our method, we show measurements of the DNA force-versus-extension relation using a range of laser intensities, and show that these measurements match the expected extensible wormlike-chain (WLC) behavior. Finally, we also demonstrate a force-clamp, in which the tension in a tether is held fixed while the extension varies as a result of molecular events.

@article{axial, abstract = {We describe a new method for calibrating optical trapping measurements in which tension is applied in the direction of the laser beam to a molecule tethered between a surface and an optically trapped bead. Specifically, we present a generally-applicable procedure for converting from the measured scattering intensity and the measured stage displacement to applied tension and bead-coverslip separation, using measurements of the light intensity scattered from an untethered, trapped bead. Our calibration accounts for a number of effects, including aberrations and the interference of forward-reflected bead-scattered light with the trapping beam. To demonstrate the accuracy of our method, we show measurements of the DNA force-versus-extension relation using a range of laser intensities, and show that these measurements match the expected extensible wormlike-chain (WLC) behavior. Finally, we also demonstrate a force-clamp, in which the tension in a tether is held fixed while the extension varies as a result of molecular events.}, added-at = {2014-02-24T12:22:14.000+0100}, author = {Mack, A H and Schlingman, D J and Regan, L and Mochrie, S G}, biburl = {https://www.bibsonomy.org/bibtex/28ef447bdaff5da09d1dc32a3006e9a32/ross_mck}, description = {Practical axial optical trapping. [Rev Sci Instrum. 2012] - PubMed - NCBI}, doi = {10.1063/1.4757862}, interhash = {71a4875ac4cdfffaca6436423296c603}, intrahash = {8ef447bdaff5da09d1dc32a3006e9a32}, journal = {Rev Sci Instrum}, keywords = {phage}, month = oct, number = 10, pages = {103106-103106}, pmid = {23126750}, timestamp = {2014-02-24T12:22:14.000+0100}, title = {Practical axial optical trapping}, url = {http://www.ncbi.nlm.nih.gov/pubmed/23126750}, volume = 83, year = 2012 }