Preparation And Characterization Of Two Hybrid Systems-Magnetic Drug-loaded Microsphere And Self-healing Hydrogel For Bone Repair

The repair and regeneration of osseous tissue defect is still a major medical health problems to solve in clinical.For treatment of bone defect,the therapeutic method most commonly used is autologous bone transplantation,allogeneic bone transplantation and so on.However,autologous transplantation has its limitation such as the lack of donor and additional injury in the donor site,allogeneic transplantation easily causes a series of complications caused by the body's rejection.Drug-loaded microspheres and medical hydrogels have attracted much interest in recent decades for their applications in pharmaceuticals,bone tissue repair and regeneration.Particularly,their organic-inorganic hybrid biomedical materials have drawn a lot of attention.Therefore,according to effective regulatory mechanism of the organic matrix to calcium phosphate rock matrix in bone matrix,we build two major systems for bone repair through the organic-inorganic hybrid technology:the preparation of micro-nano magnetic drug-loaded microsphere through both the biological mechanism of the electromagnetic field to promote tissue regeneration and the biphasic-induced in situ hybrid technology;the synthesis of self-healing hydrogel by dynamic covalent chemistry.The main contents and results of this paper are as follows:1.Preparation and characterization of micro-nano magnetic drug-loaded microsphere.The CS/nHA/Fe3O4-ICA microsphere was fabricated.A series of characterizations in vitro indicated that inorganic Fe3O4 and nHA were in situ crystallized simultaneously and uniformly dispersed in CS matrix,which used CS organic matrix as click sites.ICA had been successfully loaded.Fe3O4 and nHA trigger the self-adjusting of surface morphology,appropriate decrease of swelling and degradation properties,and prolong sustained release behavior.Taken together,it provides the possibility that the microspheres are conducive to being potential novel biomaterial for bone repair.2.Preparation and characterization of self-healing hydrogel.The CaP-GCS-OSA nano-composite hydrogel is prepared by exploiting the reversible Schiff base linkages between OSA and GCS mixed with CaP nanoparticles.The results suggested that hydrogel showes relatively porous structure and the homogeneous deposition of rod-like CaP nanoparticles.Rheology test found that elasticity of R = 0.6 hydrogel is superior and has a complete three-dimensional network structure.Herein,R = 0.6 hydrogel is as the optimal choice,which displays excellent capacity for pH-response,self-healing and injectability.With the increase of R,the hydrophilicity and degradability enhanced gradually,the swelling decreased slightly,the accumulation of drug release increased,and it had the good drug controlled-release.3.Biocompatibility characterization of two organic-inorganic hybrid systems.SD Rat osteoblast cells were used to set up in vitro evaluation model.The cell test results demonstrated that magnetic drug-loaded microspheres had a more excellent biocompatibility than CS/nHA/Fe3O4 microspheres,which could be very conducive to promoting osteoblast proliferation.Moreover,R = 0.6 hydrogel also had good biocompatibility and the ability to promote the proliferation of osteoblast cells.In conclusion,two organic-inorganic hybrid systems have good biocompatibility,and the ability to promote cell proliferation and bone tissue repair.As such,these two hybrid systems were expected to find potential applications as biomedical materials in bone repair.