Comparative Study on Protein-RichElectrospun Fibersfor in Vitro Applications

Electrospinning is the leading technology to fabricate fibrous scaffolds that mimic the architecture of the extracellular matrix of natural tissues.In order to improve the biological response, a consolidated trend involves the blending of synthetic polymers with natural proteins to form protein-rich fibersthatincludeselected biochemical cues able tomore actively support in vitro cell interaction. In this study, we compared protein-richfibers fabricated via electrospinning by the blending of poly?-caprolactone (PCL) with three different proteins, i.e., gelatin, zein,and keratin, respectively. We demonstratedthat the peculiar features of theproteins used significantly influence the morphological properties, in terms of fibersize and distribution. Moreover, keratin drastically enhances the fiberhydrophilicity(water contact angle equal to 44.3°±3.9°)with positive effects on cell interaction, as confirmed by the higher proliferation of human mesenchymal stem cells (hMSC)until 7 days.By contrast, gelatinand zeinnot equally contribute to the fiber wettability (water contact angles equal to 95.2° ±1.2°and76.3° ±4.0°,respectively)due to morphologicalconstraints,i.e., broaderfiber diameter distribution ascribable to thenon-homogeneous presence of the proteinalong the fibers,or chemical constrains,i.e., large amount of non-polar aminoacids.Accordingtoin vitro experimental studies, which includedSEM and confocal microscopy analyses and vitality assay,we concludedthatkeratinis the mostpromising proteinto be combinedwith PCLfor the fabrication of biologically instructivefibers for in vitroapplications.