title: A Model for the Transient Subdiffusive Behavior of Particles in Mucus.
abstract: In this study we have applied a model to explain the reported subdiffusion of particles in mucus, based on the measured mean squared displacements (MSD). The model considers Brownian diffusion of particles in a confined geometry, made from permeable membranes. The applied model predicts a normal diffusive behavior at very short and long time lags, as observed in several experiments. In between these timescales, we find that the "subdiffusive" regime is only a transient effect, MSD∝τα,α<1. The only parameters in the model are the diffusion-coefficients at the limits of very short and long times, and the distance between the permeable membranes L. Our numerical results are in agreement with published experimental data for realistic assumptions of these parameters. Finally, we show that only particles with a diameter less than 40 nm are able to pass through a mucus layer by passive Brownian motion.
authors.affiliation: Faculty of Engineering, Department of Applied Mathematics, University of Applied Sciences, Saarbrücken, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Ernst
authors.affiliation: Department of Experimental Physics, Saarland University, Saarbrücken, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: John
authors.affiliation: Faculty of Engineering, Department of Applied Mathematics, University of Applied Sciences, Saarbrücken, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Guenther
authors.affiliation: Department of Experimental Physics, Saarland University, Saarbrücken, Germany; Physics and Materials Science Research Unit, University of Luxembourg, Luxembourg, Luxembourg.
authors.forename: Christian
authors.initials: C
authors.lastname: Wagner
authors.affiliation: Department of Biopharmaceutics and Pharmaceutical Technology, Saarland University, Saarbrücken, Germany.
authors.forename: Ulrich F
authors.initials: UF
authors.lastname: Schaefer
authors.affiliation: Department of Biopharmaceutics and Pharmaceutical Technology, Saarland University, Saarbrücken, Germany; Helmholtz Institute for Pharmaceutical Research Saarland, Saarland University, Saarbrücken, Germany. Electronic address: Claus-Michael.Lehr@helmholtz-hzi.de.
authors.forename: Claus-Michael
authors.initials: CM
authors.lastname: Lehr
mesh_terms: D003550:Cystic Fibrosis / Q000378:metabolism; D004058:Diffusion; D006801:Humans; D008168:Lung / Q000378:metabolism; D008954:Models, Biological; D009068:Movement; D009093:Mucus / Q000378:metabolism*; D053758:Nanoparticles / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry / Q000378:metabolism; D013183:Sputum / Q000378:metabolism
chemical_list: D011092:Polyethylene Glycols