Formation of poly(epsilon-caprolactone)-embedded bioactive nanoparticles/collagen hierarchical scaffolds with the designed and customized porous structures

The biodegradable and bioactive bioscaffolds with suitable hierarchical structure, customized shape, and mechanical performance have great potential for biomedical applications especially in tissue engineering field. However, controllable and facile preparation of the related porous scaffolds remains obvious challenge. In this study, poly(epsilon-caprolactone) (PCL)-embedded hydroxyapatite (HAP) nanoparticles/collagen hierarchical scaffolds are facilely prepared basing on 3D printing of the pre-crosslinked oil in water type Pickering high internal phase emulsion (HIPE) hydrogel. To be specific, in the HAP nanoparticle stabilized Pickering HIPEs, the aqueous phase contains collagen and genipin, and the oil phase is dichloromethane solution of PCL. After the pre-crosslinking of aqueous phase, the prepared Pickering HIPE turns into emulsion hydrogel with high viscosity and shear thinning characteristics, which can be individually printed and then freeze dried to produce hierarchical scaffolds with the designed structures. The related multiscale pore structures are composed of mm-scale macropores and mu m-scale micropores, and the related porosity is higher than 84%. Increasing PCL content obviously enhances the compression stress of scaffolds, particularly the compressive stress of porous scaffold prepared with PCL content of 14 w/v% is about 9 times as large as that of porous scaffold without PCL. The results of in vitro mineralization and cell culture assay show that the porous scaffolds have favorable apatite formation ability and biocompatibility. Thus, the prepared hierarchical scaffolds with the designed structures, customized shape and adjustable performance are promising potential applications in bone tissue engineering.