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Updated: Jun 23, 2026

Characterizing Single-Molecule Conformational Changes Under Shear Flow with Fluorescence Microscopy
Published on: January 25, 2020
Microrheology with fluorescence correlation spectroscopy
Silke Rathgeber1, Hans-Josef Beauvisage, Hubert Chevreau
1Max Planck-Institute for Polymer Research, Polymer Physics, 55128 Mainz, Germany. s.rathgeber@mpip-mainz.mpg.de
Abstract:
We show that fluorescence correlation spectroscopy (FCS) using a commercial spectrometer can be applied to passive microrheological (MR) experiments. The method probes the local rheological properties of materials on length scales of the focus dimension of the confocal microscope. For a feasibility study, we performed measurements on a high molecular weight poly(ethylene oxide)-water solution to allow direct comparison of the results to previous studies using diffusing wave spectroscopy, quasielastic light scattering, and particle tracking methods. We were able to detect mean-square center-of-mass displacements ranging from somewhat better than [SYMBOL: SEE TEXT]2(t) approximately 100 nm2 up to above Deltar2(t) approximately 10(6) nm2. Thus, we were able to derive the bulk rheological shear moduli covering more than five decades in frequency (from omega
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