SKM 2023 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 11: Poster Session I

BP 11.47: Poster

Dienstag, 28. März 2023, 12:30–15:30, P1

Upconversion-nanoparticle optical trapping for ultraresolution motor protein measurements — •Aleksandr Kostarev and Erik Schäffer — Universität Tübingen, ZMBP, Tübingen, Deutschland

Molecular machines are essential for many cellular processes. For example, kinesin motor proteins transport cargo along microtubule cytoskeletal filaments. The stepping and force generation of single motors can be measured using optical tweezers. However, the spatiotemporal resolution achieved with common optical tweezers probes is insufficient to detect fast steps in particular at low forces. To improve the resolution, nanoparticles are required as optical tweezers probes. Upconversion nanoparticles trapped near resonance of their electric susceptibility have the highest reported trapping efficiency and are chemically stable. Yet, they have not been used for biophysical measurements. To use them, we have integrated a near-resonance trapping laser, detector, and laser steering system in an optical tweezers system. Calibration measurements show that the upconversion nanoparticles indeed have a very high trapping efficiency when trapped with a laser near resonance compared to off-resonance trapping. Once functionalized with the motors, trapping experiments will shed light on how weak kinesin motors step and diffuse on microtubules. In the long term, upconversion-nanopartical optical trapping will improve the spatiotemporal resolution of optical tweezers and shed light on the working mechanism of a wide range of molecular machines.