title: Tensile properties of human collagen fibrils and fascicles are insensitive to environmental salts.
abstract: To carry out realistic in vitro mechanical testing on anatomical tissue, a choice has to be made regarding the buffering environment. Therefore, it is important to understand how the environment may influence the measurement to ensure the highest level of accuracy. The most physiologically relevant loading direction of tendon is along its longitudinal axis. Thus, in this study, we focus on the tensile mechanical properties of two hierarchical levels from human patellar tendon, namely: individual collagen fibrils and fascicles. Investigations on collagen fibrils and fascicles were made at pH 7.4 in solutions of phosphate-buffered saline at three different concentrations as well as two HEPES buffered solutions containing NaCl or NaCl + CaCl2. An atomic force microscope technique was used for tensile testing of individual collagen fibrils. Only a slight increase in relative energy dissipation was observed at the highest phosphate-buffered saline concentration for both the fibrils and fascicles, indicating a stabilizing effect of ionic screening, but changes were much less than reported for radial compression. Due to the small magnitude of the effects, the tensile mechanical properties of collagen fibrils and fascicles from the patellar tendon of mature humans are essentially insensitive to environmental salt concentration and composition at physiological pH.
authors.affiliation: Nano-Science Center, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: René B
authors.initials: RB
authors.lastname: Svensson
authors.forename: Tue
authors.initials: T
authors.lastname: Hassenkam
authors.forename: Colin A
authors.initials: CA
authors.lastname: Grant
authors.forename: S Peter
authors.initials: SP
authors.lastname: Magnusson
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology*; D024022:Fibrillar Collagens / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D018625:Microscopy, Atomic Force; D017847:Patellar Ligament / Q000033:anatomy & histology / Q000187:drug effects / Q000648:ultrastructure; D012965:Sodium Chloride / Q000494:pharmacology*; D012996:Solutions; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000187:drug effects
chemical_list: D024022:Fibrillar Collagens; D012996:Solutions; D012965:Sodium Chloride; D002122:Calcium Chloride