Berlin 2005 – scientific programme
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AKB: Biologische Physik
AKB 50: Imaging and Microscopy
AKB 50.5: Talk
Monday, March 7, 2005, 17:00–17:15, TU H2013
Imaging of molecular interactions with Photonic Force Microscopy — •Alexander Rohrbach1, Ernst Stelzer1, Holger Kress1, and Nils Becker2 — 1European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg — 2Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden
Molecular interactions are controlled by the thermal environment of the binding partners. The resulting energy fluctuations offer a broad spectrum of orientations, distances and kinetics to the molecules enabling an optimal interaction. This concept is exploited in photonic force microscopy: An optically trapped probe fluctuates in its position as a function of the trapping parameters and the probes local environment. The probe position can be tracked interferometrically in the MHz range with a precision of 1 - 5 nm in three dimensions. The fluctuations are altered by external enthalpic or entropic forces acting on the probe. These interactions can be visualized by recording the particles three-dimensional trajectories, resulting in an interaction profile with nm resolution. Two applications illustrate the potential of this technique: single molecule experiments with the protein Myosin II to determine its nano-mechanics; and experiments resolving the temporal and spatial binding of particles to macrophage membranes.