7712
2014
2014
eng
1847
1858
12
postprint
The Royal Society of Chemistry
Cambridge
1
2015-05-22
2014-11-26
--
Non-universal tracer diffusion in crowded media of non-inert obstacles
We study the diffusion of a tracer particle, which moves in continuum space between a lattice of excluded volume, immobile non-inert obstacles. In particular, we analyse how the strength of the tracer–obstacle interactions and the volume occupancy of the crowders alter the diffusive motion of the tracer. From the details of partitioning of the tracer diffusion modes between trapping states when bound to obstacles and bulk diffusion, we examine the degree of localisation of the tracer in the lattice of crowders. We study the properties of the tracer diffusion in terms of the ensemble and time averaged mean squared displacements, the trapping time distributions, the amplitude variation of the time averaged mean squared displacements, and the non-Gaussianity parameter of the diffusing tracer. We conclude that tracer–obstacle adsorption and binding triggers a transient anomalous diffusion. From a very narrow spread of recorded individual time averaged trajectories we exclude continuous type random walk processes as the underlying physical model of the tracer diffusion in our system. For moderate tracer–crowder attraction the motion is found to be fully ergodic, while at stronger attraction strength a transient disparity between ensemble and time averaged mean squared displacements occurs. We also put our results into perspective with findings from experimental single-particle tracking and simulations of the diffusion of tagged tracers in dense crowded suspensions. Our results have implications for the diffusion, transport, and spreading of chemical components in highly crowded environments inside living cells and other structured liquids.
urn:nbn:de:kobv:517-opus4-77128
online registration
Au-006431
Phys. Chem. Chem. Phys., 2015,17, 1847-1858. - DOI: 10.1039/C4CP03599B
<a href="http://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/7711">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
Surya K. Ghosh
Andrey G. Cherstvy
Ralf Metzler
Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
186
eng
uncontrolled
escence correlation spectroscopy
eng
uncontrolled
single-particle tracking
eng
uncontrolled
anomalous diffusion
eng
uncontrolled
living cells
eng
uncontrolled
physiological consequences
eng
uncontrolled
langevin equation
eng
uncontrolled
infection pathway
eng
uncontrolled
excluded volume
eng
uncontrolled
brownian-motion
eng
uncontrolled
random-walks
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
Open Access
https://publishup.uni-potsdam.de/files/7712/pmnr186.pdf
9446
2013
2013
eng
20220
20235
postprint
1
--
2013-09-09
--
Population splitting, trapping, and non-ergodicity in heterogeneous diffusion processes
We consider diffusion processes with a spatially varying diffusivity giving rise to anomalous diffusion. Such heterogeneous diffusion processes are analysed for the cases of exponential, power-law, and logarithmic dependencies of the diffusion coefficient on the particle position. Combining analytical approaches with stochastic simulations, we show that the functional form of the space-dependent diffusion coefficient and the initial conditions of the diffusing particles are vital for their statistical and ergodic properties. In all three cases a weak ergodicity breaking between the time and ensemble averaged mean squared displacements is observed. We also demonstrate a population splitting of the time averaged traces into fast and slow diffusers for the case of exponential variation of the diffusivity as well as a particle trapping in the case of the logarithmic diffusivity. Our analysis is complemented by the quantitative study of the space coverage, the diffusive spreading of the probability density, as well as the survival probability.
urn:nbn:de:kobv:517-opus4-94468
online registration
Phys. Chem. Chem. Phys. (2013) Nr. 15, S. 20220-20235. DOI: 10.1039/C3CP53056F
Keine Nutzungslizenz vergeben - es gilt das deutsche Urheberrecht
Andrey G. Cherstvy
Ralf Metzler
Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
236
eng
uncontrolled
anomalous diffusion
eng
uncontrolled
disordered media
eng
uncontrolled
fractional dynamics
eng
uncontrolled
infection pathway
eng
uncontrolled
inhomogeneous-media
eng
uncontrolled
intracellular-transport
eng
uncontrolled
langevin equation
eng
uncontrolled
living cells
eng
uncontrolled
random-walks
eng
uncontrolled
single-particle tracking
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
Open Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/9446/pmnr236_online.pdf
7402
2014
2014
eng
1591
1601
11
168
postprint
1
2015-03-20
2014-01-02
--
Particle invasion, survival, and non-ergodicity in 2D diffusion processes with space-dependent diffusivity
We study the thermal Markovian diffusion of tracer particles in a 2D medium with spatially varying diffusivity D(r), mimicking recently measured, heterogeneous maps of the apparent diffusion coefficient in biological cells. For this heterogeneous diffusion process (HDP) we analyse the mean squared displacement (MSD) of the tracer particles, the time averaged MSD, the spatial probability density function, and the first passage time dynamics from the cell boundary to the nucleus. Moreover we examine the non-ergodic properties of this process which are important for the correct physical interpretation of time averages of observables obtained from single particle tracking experiments. From extensive computer simulations of the 2D stochastic Langevin equation we present an in-depth study of this HDP. In particular, we find that the MSDs along the radial and azimuthal directions in a circular domain obey anomalous and Brownian scaling, respectively. We demonstrate that the time averaged MSD stays linear as a function of the lag time and the system thus reveals a weak ergodicity breaking. Our results will enable one to rationalise the diffusive motion of larger tracer particles such as viruses or submicron beads in biological cells.
urn:nbn:de:kobv:517-opus4-74021
online registration
Au-006605
Soft Matter, 2014, 10, S. 1591-1601 - DOI: 10.1039/c3sm52846d
<a href="http://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/7400">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
Andrey G. Cherstvy
Aleksei V. Chechkin
Ralf Metzler
Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
paper 168
eng
uncontrolled
adenoassociated virus
eng
uncontrolled
anomalous diffusion
eng
uncontrolled
cytoplasm
eng
uncontrolled
endosomal escape
eng
uncontrolled
escherichia-coli
eng
uncontrolled
infection pathway
eng
uncontrolled
intracellular-transport
eng
uncontrolled
living cells
eng
uncontrolled
models
eng
uncontrolled
trafficking
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
Open Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/7402/pmnr168.pdf