Berlin 2008 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Posters I

BP 7.34: Poster

Monday, February 25, 2008, 17:00–19:30, Poster A

Localized heating effects in optical tweezers investigated using ionic currents through nanopores — •Jan Henning Peters and Ulrich Felix Keyser — Institut für Experimentelle Physik I, Universität Leipzig

Optical tweezers are a powerful and widely used experimental tool in biological physics including single molecule investigations. The strongly focused laser-beam in such a setup can reach power densities in the order of 10⁸ W/cm² that cause significant heating exceeding 10K per Watt of incident laser power for a 1064nm-Laser ([1],[2]). As the reaction constants of biomolecules are temperature dependent, heating effects should be considered in biophysical experiments.

The ionic current through a nanopore depends on the local temperature in a well-defined manner and hence can be used for temperature measurements with high spatial resolution [1]. We compare experiments using nanopores with numerical finite element calculations and investigate the dependence of heating effects on parameters like geometry and thermal conductivity of water and nanopore material. We were able to confirm earlier findings as the logarithmic dependence of the maximal temperature on the size of the system [2] and also gain a more detailed insight into the temperature distribution found in optical tweezers.

[1] U. Keyser, et al., Nano Letters Vol. 5 No. 11 2253-2256

[2] E. Peterman, et al., Biophys. Journal Vol. 84, 1308-1316