Fiber Angle and Aspect Ratio Influence the Shear Mechanics of Electrospun Nanofibrous Scaffolds

Fibrocartilages, including the meniscus of the knee and annulus fibrosus (AF) of the intervertebral disc, are dense connective tissues with an organized collagenous structure that play critical roles in motion and load transmission across joints. Proper mechanical function of these tissues is dependent on their structure and composition, both of which are compromised with degeneration. Tissue engineering strategies present a promising alternative to current treatments. Aligned electrospun scaffolds show promise for tissue engineering of fibrous soft tissues due to their ability to direct cell alignment and matrix deposition [1]. Furthermore, this matrix deposition results in constructs with near-native tensile properties. However, the large multi-directional forces experienced by these tissues in vivo requires that engineered constructs resist considerable shear and compressive loads as well. Unfortunately, shear properties of electrospun scaffolds are not well established. Simple shear is an appealing testing configuration because the application of tensile prestrain allows for combined fiber stretch and shear as occurs in situ. However, due to possible strain field heterogeneity, proper analysis of strain distributions must be performed [2]. The objective of this study was to quantify the effects of fiber orientation and sample aspect ratio on the shear properties of aligned electrospun scaffolds.