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A chitosan (CS)/hydroxyapatite (HAP) nanohybrid scaffold with high porosity and homogeneous nanostructure was fabricated through a bionic treatment combined with thermally-induced phase separation. The nano-HAP particles were formed in situ in the scaffold at room temperature instead of mechanically mixing the powders with the polymer component. The scaffold was macroporous with a pore size of about 100-136 microm. The nano-sized HAP particles with diameters of 90-200 nm were scattered homogeneously in the interactively connective pores. Both the improvement of the compressive modulus and yield strength of the scaffolds showed that the in situ nano-HAP particles reinforced the microstructure of the scaffold. The in vitro bioactivity study carried out in simulated body fluid (SBF) indicated good mineralization activity. The crystallization phenomenon suggested that the nano-HAP particles have positive impacts on directing apatite crystallization in the scaffold and led to the good bioactivity of the nanohybrid scaffold.

In this study the chitosan/collagen/icariin composite scaffolds for nerve regeneration were produced by blending and crosslinking chitosan with collagen and icariin. The microstructure of the composite scaffolds was observed by scanning electron microscopy. 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide and attachment assays were conducted, respectively, to investigate the biocompatibility of the scaffolds. Cell cultural tests showed that the channel-structured porous scaffolds acted as a positive factor to support connective nerve cell growth. After culture, cells showed a clear flow trend to move close to the composite scaffolds in culture solution, arranging in spiral-like, and aligned parallel to the orientation of the channel structure on the surface of scaffolds. When compared to pure chitosan and chitosan/collagen scaffolds, Schwann cells and PC12 cells on the chitosan/collagen/icariin composite scaffolds exhibited the greatest proliferation and longest average neurite length. These results suggested that the chitosan/collagen/icariin composite scaffolds are potential cell carriers in nerve tissue engineering.

Owing to the unique characters of the hybrid scaffold components, a novel biodegradable porous composite scaffold was prepared. The nano hydroxyapatite (HAP) (73~136 nm) was crystallized in situ on the organic polyelectrolyte complex matrix through a biomimetic method. The polyelectrolyte complex composed of chitosan and hyaluronic acid had strong impacts on the formation of the nano HAP and directed in situ crystallization of the nano HAP as template. The in situ nano HAP reduced the interfacial energy and presented nano intensifier to the nano hybrid scaffold. Meanwhile, the scaffold kept high porosity.

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