Effect of humidity and benign solvent composition on electrospinning of collagen nanofibrous sheets

This study investigated the effects of relative humidity (RH; 30% and 60%) and the presence of an environmentally benign solvent consisting of 20 x phosphate-buffered saline/ethanol (1:1, 1:1.3, and 1:1.5 ratios) on the fabrication of collagen nanofibrous sheets. The sheets formed nanofibers without beads in the 1:1.5 solvent at 30% RH. The wettability of the crosslinked sheets was roughness-dependent. Wettability increased with ethanol content at 30% RH but decreased at 60% RH. The stability of the collagen structure increased with higher ethanol content, and nanofibers in the 1:1.5 solvent showed full recovery of the diffraction pattern of pristine collagen after crosslinking. Isolated adipose tissue-derived stem cells (ADSCs) cultured on nanofibrous sheets showed good attachment at 1 week. However, because of nanofiber degradation, attachment was non-existent (1:1) or reduced (1:1.3) at 60% RH at 8 weeks. These results demonstrate that ethanol content influences the structural stability of collagen and that both humidity and ethanol content affect the morphological characteristics of collagen nanofibers and cell attachment to nanofibrous sheets. (C) 2016 Elsevier B.V. All rights reserved.