Drug-loaded Chitosan/Apatite Composites With Multiscale Biomimetic Bone Structure

The multilayer hydrogels with structure similar to that of the outer circumferential lamella and a gap between these hydrogel layers allow cell adhesion and drug delivery. However the poor mechanical property,connectivity and tissue conduction have hinder the application in tissue engineering and drug delivery. We have prepared chitosan/apatite composites with good mechanical property for imitating the structure and components precisely.We have fabricated the chitosan/apatite composite scaffold via commutative soaking. Also the morphology of multilayer hydrogels was o bserved and the effect of apatite component on the layer thickness and porosity was figured out using optical microscope. The microspheres surface was analyzed using SEM and the relationship between the processing parameter and the microporous structure also was determined. The release behavior of rifampicin from bio-inspired chitosan/apatite scaffold was investigated. The drug rifampicin was loaded by physical adsorption and biological mineralization, respectively. The effects of different components of the block layer and multilayer structure on the release behavior was evaluatedThe results show that at the same time, the layer is not influenced by apatite content. The layer thickness decrease with the increased of apatite(4 ~ 22 μm). The drug rifampicin was loaded by physical adsorption and biological mineralization. The release behavior was fitted by Korsmeyer-Peppas and Weibull models(n<0.45,b<0.75) and show that the drug release rate depended on the diffusion in PBS. The drug release behavior with l ong release time and sustained release effect was acquired by biological mineralization. The block layer outside the scaffold and changing the layer arrangement could prolong the drug release time. In addition, the effect of structure parameters(5%~13%) o n sustained release behavior was larger than that of the addition of apatite(1%~5%).The research shows that apatite could not affect the layer number with the same commutative time. The layer thickness of multilayer hydrogels decreased by increasing the apatite components. The chitosan/apatite composite microspheres were prepared through injection, and the size of microsphere increased by increasing apatite components(0.75~1.3mm). The chitosan/apatite composite microspheres with different apatite componen ts following by low temperature process and freeze-drying exhibit interconnected porous structure and also have porous structure after high temperature sintering. A multi-scale, high-porosity(40%~67%) bio-inspired cancellous bone could be fabricated using these chitosan/apatite microspheres.