Preparation And Mechanical Properties Of Guided Bone Regeneration Membrane Carried Chitosan Microspheres

Regeneration and repair of bone defects has become an important issue forregenerative medicine research at present. Numerous studies show that guidedbone regeneration membrane (GBR) technology is an effective method to repairbone defects. Ideal GBR membranes meet requirements, such as goodbiocompatibility, bioactivity and osteoconductivity. Meanwhile, it has a certainmechanical strength to resist the invasion of the surrounding fibrous tissue.In this study, we prepared GBR membrane with biocompatible andbiodegradable chitosan (CS). To improve the mechanical strength andosteogenic activity of CS membrane, nano-hydroxyapatite (nHA) and CScomposite microspheres were introduced into CS membrane. It expects to play abarrier role, has good bone conduction, and promotes regeneration of bonedefects.Previous studies always prepared nHA/CS composite microspheres usingthe principle of blending emulsification. In the present study, nHA/CScomposite microspheres were prepared by in situ biomimetic method. Due to thehigh surface activity and large surface area of nHA crystals, we introduced ituniformly into a polymer matrix (CS) and chemical bond with the active groupswas produced. The physical and chemical properties of the compositemicrospheres were investigated by scanning electronic microscopy (SEM),X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and laser particle size analyzer. Theresults indicate that the composite microspheres are spherical with average sizeof8.62μm and dispersed uniformly. Moreover, the nHA crystals are disperseduniformly within composite microspheres and bonded with CS matrix. Thecomposite microspheres have great potential applications in bone tissueengineering and drug delivery system.The GBR membranes containing pure CS microspheres, nHA/CScomposite microspheres fabricated by in situ biomimetic and co-mixing methodwere designed and prepared, respectively. The morphologies and architecturesof the surface and cross-section of the three GBR membranes were investigatedby SEM. The mechanical properties of the membranes were tested usinguniversal electronic testing machine. The results show that, after introduction ofdifferent microspheres, granular protuberances appear on the membrane surface.The microspheres are embedded in the GBR membranes. Cross-sectionalmorphologies show that obvious gaps appear between CS microspheres and CSmatrix. nHA crystals aggregation in co-mixing nHA/CS composite microspheresis adverse to the combination between CS matrix and composite microspheres.nHA/CS composite microspheres fabricated by in situ method integrated tightlywith CS matrix. nHA crystal on the surface of the microspheres can effectivelylink with CS matrix. Tensile tests show that, compared to pure CS membrane,after introduction of different microspheres, the elongation at break of thesamples decreases. Especially, nHA/CS composite microspheres fabricated by insitu biomimetic method reaches5.610.95%. While, the elasticity modulus andultimate strength of the samples carried in situ biomimetic and co-mixingcomposite microspheres improves significantly. The modulus and ultimatestrength of the membranes carried in situ composite microspheres reach766.27220.675and43.3180.951MPa, respectively.