Camera-based three-dimensional real-time particle tracking at kHz rates and Ångström accuracy.

Alexander Huhle, Daniel Klaue, Hergen Brutzer, Peter Daldrop, Sihwa Joo, Oliver Otto, Ulrich F Keyser, Ralf Seidel

OAI: oai:www.repository.cam.ac.uk:1810/309446 • DOI: 10.17863/CAM.56536

Optical and magnetic tweezers are widely employed to probe the mechanics and activity of individual biomolecular complexes. They rely on micrometre-sized particles to detect molecular conformational changes from the particle position. Real-time particle tracking with Ångström accuracy has so far been only achieved using laser detection through photodiodes. Here we demonstrate that camera-based imaging can provide a similar performance for all three dimensions. Particle imaging at kHz rates is combined, with real-time data processing being accelerated by a graphics-processing unit. For particles that are fixed in the sample cell we can detect 3-Å-sized steps that are introduced by cell translations at rates of 10 Hz, while for DNA-tethered particles 5 Å steps at 1 Hz can be resolved. Moreover, 20 particles can be tracked in parallel with comparable accuracy. Our approach provides a simple and robust way for high-resolution tweezer experiments using multiple particles at a time.

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