Incremental changes in anisotropy induce incremental changes in the material properties of electrospun scaffolds

Electrospinning can be used to selectively process a variety of natural and synthetic polymers into highly porous scaffolds composed of nano-to-m diameter fibers. This process shows great potential as a gateway to the development of physiologically relevant tissue engineering scaffolds. In this study, we examine how incremental changes in fiber alignment modulate the material properties of a model scaffold. We prepared electrospun scaffolds of gelatin composed of varying fiber diameters and degrees of anisotropy. The scaffolds were cut into a series of "dog-bone" shaped samples in the longitudinal, perpendicular and transverse orientations and the relative degree of fiber alignment, as measured by the fast Fourier transform (FFT) method, was determined for each sample. We measured peak stress, peak strain and the modulus of elasticity as a function of fiber diameter and scaffold anisotropy. Fiber alignment was the variable most closely associated with the regulation of peak stress, peak strain and modulus of elasticity. Incremental changes, as judged by the FFT method, in the proportion of fibers that were aligned along a specific axis induced incremental changes in peak stress in the model scaffolds. These results underscore the critical role that scaffold anisotropy plays in establishing the material properties of an electrospun tissue engineering scaffold and the native extracellular matrix. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.