Diffusion and segmental dynamics of rodlike molecules by fluorescence correlation spectroscopy

Abstract

The dynamics of weakly bending polymers is analyzed on the basis of a Gaussian semiflexible chain model and the fluorescence correlation spectroscopy (FCS) correlation function is determined. Particular attention is paid to the influence of the rotational motion on the decay of the FCS correlation function. An analytical expression for the correlation function is derived, from which the averaged segmental mean square displacement can be determined independent of any specific model for the polymer dynamics. The theoretical analysis exhibits a strong dependence of the correlation function on the rotational motion for semiflexible polymers with typical lengths and persistence lengths of actin filaments or fd viruses. Hence, FCS allows for a measurement of the rotational motion of such semiflexible polymers. The theoretical results agree well with experimental measurements on actin filaments and confirm the importance of large relaxation times.

Conformational and dynamical properties of semiflexible polymers in the presence of active noise

“…2(b). At low Pe, we find the well-know dependence τ n /τ 1 ∼ (2n − 1) −4 valid for passive semiflexible polymers [52,56,60]. With increasing Pe, the ratio τ n /τ 1 shifts to larger values, and for Pe 50 the small-mode-number relaxation times 050001-4 .…”

“…Figure 4 displays MSDs of flexible and semiflexible polymers. For passive polymers, we find the well-known Rouse dependence √ t for flexible polymers [59] and the dependence t 3/4 for semiflexible polymers [56,61,62] at t/τ 1 1. In the presence of activity, the diffusivity is significantly enhanced, as already noted before [23,41,63].…”

Conformations, hydrodynamic interactions, and instabilities of sedimenting semiflexible filaments

“…with the persistence length l p . [26,27] In the following, we will neglect the bond term, i.e., the term with the second derivative and focus on bending stiffness only. The expansion…”

Polymer Dynamics, Fluorescence Correlation Spectroscopy, and the Limits of Optical Resolution

“…In a recent paper, Shusterman et al [6] introduced an analysis method for FCS data, which they used to analyze the nanoscale conformational dynamics of single-and double-stranded DNA, reporting Zimm instead of Rouse dynamics for the studied molecules. This finding has spurred considerable theoretical work in an effort to explain this unexpected result [7][8][9]. Meanwhile, the analysis method of Shusterman et al has found widespread application in FCSbased studies of polymer dynamics Ref.…”