title: Quantification of Interfibrillar Shear Stress in Aligned Soft Collagenous Tissues via Notch Tension Testing.
abstract: The mechanical function of soft collagenous tissues is largely determined by their hierarchical organization of collagen molecules. While collagen fibrils are believed to be discontinuous and transfer load through shearing of the interfibrillar matrix, interfibrillar shear stresses have never been quantified. Scaling traditional shear testing procedures down to the fibrillar length scale is impractical and would introduce substantial artifacts. Here, through the use of a novel microscopic variation of notch tension testing, we explicitly demonstrate the existence of interfibrillar shear stresses within tendon fascicles and provide the first measurement of their magnitude. Axial stress gradients along the sample length generated by notch tension testing were measured and used to calculate a value of 32 kPa for the interfibrillar shear stress. This estimate is comparable to the interfibrillar shear stress predicted by previous multiscale modeling of tendon fascicles, which supports the hypothesis that fibrils are discontinuous and transmit load through interfibrillar shear. This information regarding the structure-function relationships of tendon and other soft collagenous tissues is necessary to identify potential causes for tissue impairment with degeneration and provide the foundation for developing regenerative repair strategies or engineering biomaterials for tissue replacement.
authors.affiliation: Department of Bioengineering. University of Pennsylvania, 240 Skirkanich Hall, 210 South 33rd St, Philadelphia, PA 19104.
authors.forename: Spencer E
authors.initials: SE
authors.lastname: Szczesny
authors.affiliation: Delaware Biotechnology Institute, 15 Innovation Way, Suite 117, Newark, DE 19716.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Caplan
authors.affiliation: Carl Zeiss Microscopy, One Zeiss Drive, Thornwood, NY 10594.
authors.forename: Pal
authors.initials: P
authors.lastname: Pedersen
authors.affiliation: Department of Biomedical Engineering, University of Delaware, 161 Colburn Lab, 150 Academy Street, Newark, DE 19716.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Elliott
mesh_terms: D000818:Animals; D003094:Collagen; D005109:Extracellular Matrix; D005780:Gelatin; D051381:Rats; D033081:Shear Strength; D013314:Stress, Mechanical; D013710:Tendons
chemical_list: D005780:Gelatin; D003094:Collagen