title: Modulation of collagen by addition of Hofmeister salts.
abstract: Collagen can be modified by addition of chaotropic or kosmotropic salts of the reversed Hofmeister series. Hence, telopeptide-poor collagen type I was suspended in H2SO4 (pH 2) and 0.05-0.5 M KCl and KNO3 (chaotropes), as well as KI and KSCN (kosmotropes). Rheological parameters, including storage and loss modulus, intrinsic viscosity, and critical overlap concentration, were assessed and the microstructure was characterized by applying confocal laser scanning microscopy and scanning electron microscopy. The addition of up to 0.1 M KCl and 0.05 M KNO3 increased the intrinsic viscosity from 1.22 to 1.51 L/g without salt to a maximal value of 1.74 L/g and decreased the critical overlap concentration from 0.66 to 0.82 g/L to a minimal value of 0.57 g/L. Higher salt concentrations increased the collagen-collagen interactions due to ions withdrawing the water from the collagen molecules. Hence, 0.1 M KSCN delivered the largest structures with the highest structure factor, area value and the highest critical overlap concentration with 17.6 L/g. Overall, 0.5 M salt led to salting out, with chaotropes forming fine precipitates and kosmotropes leading to elastic three-dimensional networks. The study demonstrated that collagen entanglement and microstructure depend strongly on the ionic strength and type of salt.
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Anja Maria
authors.initials: AM
authors.lastname: Oechsle
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Landenberger
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Gibis
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Stefan Björn
authors.initials: SB
authors.lastname: Irmscher
authors.affiliation: Department of Food Process Engineering and Food Powders, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kohlus
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany. Electronic address: j.weiss@uni-hohenheim.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D024042:Collagen Type I / Q000737:chemistry* / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000737:chemistry; D011189:Potassium Chloride / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D011193:Potassium Iodide / Q000737:chemistry; D066329:Protein Aggregates; D012492:Salts / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry; D013861:Thiocyanates; D014783:Viscosity
chemical_list: D024042:Collagen Type I; D009566:Nitrates; D017680:Potassium Compounds; D066329:Protein Aggregates; D012492:Salts; D013464:Sulfuric Acids; D013861:Thiocyanates; D011193:Potassium Iodide; D011189:Potassium Chloride; C023844:potassium nitrate; C009941:potassium thiocyanate
keywords: Bovine telopeptide-poor collagen type I; Lyotropic series; Microstructure