title: A foam model highlights the differences of the macro- and microrheology of respiratory horse mucus.
abstract: Native horse mucus is characterized with micro- and macrorheology and compared to hydroxyethylcellulose (HEC) gel as a model. Both systems show comparable viscoelastic properties on the microscale and for the HEC the macrorheology is in good agreement with the microrheology. For the mucus, the viscoelastic moduli on the macroscale are several orders of magnitude larger than on the microscale. Large amplitude oscillatory shear experiments show that the mucus responds nonlinearly at much smaller deformations than HEC. This behavior fosters the assumption that the mucus has a foam like structure on the microscale compared to the typical mesh like structure of the HEC, a model that is supported by cryogenic-scanning-electron-microscopy (CSEM) images. These images allow also to determine the relative amount of volume that is occupied by the pores and the scaffold. Consequently, we can estimate the elastic modulus of the scaffold. We conclude that this particular foam like microstructure should be considered as a key factor for the transport of particulate matter which plays a central role in mucus function with respect to particle penetration.
authors.affiliation: Experimental Physics, Saarland University, Campus, 66123 Saarbrücken, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Gross
authors.affiliation: Biopharmaceutics and Pharmaceutical Technology, Department of Pharmacy, Saarland University, Campus, 66123 Saarbrücken, Germany.
authors.forename: Afra
authors.initials: A
authors.lastname: Torge
authors.affiliation: Biopharmaceutics and Pharmaceutical Technology, Department of Pharmacy, Saarland University, Campus, 66123 Saarbrücken, Germany.
authors.forename: Ulrich F
authors.initials: UF
authors.lastname: Schaefer
authors.affiliation: Biopharmaceutics and Pharmaceutical Technology, Department of Pharmacy, Saarland University, Campus, 66123 Saarbrücken, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Schneider
authors.affiliation: Biopharmaceutics and Pharmaceutical Technology, Department of Pharmacy, Saarland University, Campus, 66123 Saarbrücken, Germany; Department of Drug Delivery, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany.
authors.forename: Claus-Michael
authors.initials: CM
authors.lastname: Lehr
authors.affiliation: Experimental Physics, Saarland University, Campus, 66123 Saarbrücken, Germany; Physics and Materials Science Research Unit, University of Luxembourg, 162a avenue de la Faencerie, L-1511 Luxembourg, Luxembourg. Electronic address: c.wagner@mx.uni-saarland.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Wagner
mesh_terms: D000818:Animals; D002482:Cellulose / Q000031:analogs & derivatives / Q000032:analysis; D055119:Elastic Modulus; D006736:Horses; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D009093:Mucus / Q000502:physiology*; D012137:Respiratory System; D012212:Rheology; D014783:Viscosity
chemical_list: D002482:Cellulose; C002283:hydroxyethylcellulose
keywords: Horse; LAOS; Microrheology; Mucus; Respiratory mucus; SAOS