Polydopamine-Templated Hydroxyapatite Reinforced Polycaprolactone Composite Nanofibers with Enhanced Cytocompatibility and Osteogenesis for Bone Tissue Engineering

Nanohydroxyapatite (HA) synthesized by biomimetic strategy is a promising nanomaterial as bone substitute due to its physicochemical features similar to those of natural nanocrystal in bone tissue. Inspired by mussel adhesive chemistry, a novel nano-HA was synthesized in our work by employing polydopamine (pDA) as template under weak alkaline condition. Subsequently, the as-prepared pDA-templated HA (tHA) was introduced into polycaprolactone (PCL) matrix via coelectrospinning, and a bioactive tHA/PCL composite nanofiber scaffold was developed targeted at bone regeneration application. Our research showed that tHA reinforced PCL composite nanofibers exhibited favorable cytocompatibility at given concentration of tHA (0-10 w.t%). Compared to pure PCL and traditional nano-HA enriched PCL (HA/PCL) composite nanofibers, enhanced cell adhesion, spreading and proliferation of human mesenchymal stem cells (hMSCs) were observed on tHA/PCL composite nanofibers on account of the contribution of pDA present in tHA. More importantly, tHA nanoparticles exposed on the surface of composite nanofibers could further promote osteogenesis of hMSCs in vitro even in the absence of osteogenesis soluble inducing factors when compared to traditional HA/PCL scaffolds, which was supported by in vivo test as well according to the histological analysis. Overall, our study demonstrated that the developed tHA/PCL composite nanofibers with enhanced cytocompatibility and osteogenic capacity hold great potential as scaffolds for bone tissue engineering.