Biomimetic Fabrication And Biocompatibility Study Of Emulsion-templated Hybrid Scaffolds Used For Bone Repair

Here,we were devoted to preparing the biomaterials used for bone defects.Considering the problem of dissolution and coexistence of the natural and synthetic polymers,emulsion template combined with organic-inorganic hybrid technology were used in this study.In recent years,these strategies have provided an attractive strategy for preparation of the porous bio-materials,especially the porous bio-scaffolds used for bone repair and replacement.The main contents and results of this study are as follows:1.Preparation and characterization of the nano hydroxyapatite(nHAP)stabilized oil-in-water(O/W)micro/nano hybrid biomimetic scaffolds.Here,the aqueous solution of carboxymethyl chitosan(CMCS)was acted as the water phase,the dichloromethane solution of PLGA was acted as the oil phase,nHAP particles were used as effective emulsifiers to produce stable O/W emulsions.Meanwhile,glutaraldehyde was added to fix emulsion templates.The nHAP/CMCS/PLGA scaffolds were fabricated by emulsification,solvent evaporation and freeze-drying.FTIR,XRD and SEM showed that glutaraldehyde was successfully reacted with CMCS,the prepared scaffolds possessed highly interconnected pore structures,PLGA microspheres and nHAP particles were evenly dispersed on the surface of the scaffolds.The results of TG-DSC showed that the scaffolds were of good thermal stability.With the increase of nHAP,the pore density of the scaffolds increased,the mechanical properties also enhanced,while the porosity and swelling rate together with the degradation rate were reduced.We loaded icariin(ICA)into the scaffolds to study the drug release properties,result showed that with the increase of nHAP,ICA showed a burst release in the early stage and a sustained release in the later stage.The scaffolds also showed good biological activity when soaked in simulated body fluid(SBF),and excellent blood compatibility when evaluated by hemolysis tested.The key point is that the scaffolds had good biocompatibility,which could not only promote the cell adhesion,proliferation and differentiation,but also provide appropriate space and mechanical properties for bone tissue regeneration,2.Preparation and characterization of the abalone shell particles(AS)stabilized oil-in-water(O/W)micro/nano hybrid biomimetic scaffolds.In this section,the scaffolds were prepared by oil-in-water(O/W),the water phase was composed of carboxymethyl chitosan(CMCS)and collagen(Col),and the oil phase was composed of PLGA,and AS were acted as the hydrophilic emulsifiers,glutaraldehyde was used as cross-linking agent to fix emulsion templates.The AS/CMCS/Col/PLGA scaffolds were prepared by emulsification,solvent evaporation and freeze-drying.Whereafter,a series of characterizations were made to study the properties of the scaffolds.FTIR,XRD and SEM showed that glutaraldehyde was successfully reacted with CMCS and Col,AS were mainly composed of CaCO3,and with the increase of the Col,the micro-morphology and the structural of pores were turned poor.Thus,the scaffolds with interconnected pores and uniform pore size were studied further.SEM showed that PLGA microspheres and AS particles were evenly dispersed on the surface of the scaffolds.TG-DSC indicated that the scaffolds had good thermal stability.With the increase of AS,the density of the pores increased,the mechanical properties also increased.However,the porosity,swelling rate and degradation rate were decreased,which was conducive to nutrient transmission and mechanical support for tissue repair and regeneration.Studies of in vitro mineralization and blood compatibility showed that the scaffolds had good biological activity and blood compatibility.We also studied the in vitro biocompatibility of the scaffolds when co-cultured with osteoblasts,which showed strong vitality and differentiation ability.In summery,moderate AS and Col can not only improve the physicochemical properties,but also enhance the biocompatibility,especially the S3 and C+S3.In conclusion,the two oil-in-water(O/W)micro/nano hybrid biomimetic scaffolds all had good biocompatibility,and they all could improve the adhesion of the osteoblasts.These results indicate that they are promising candidates for bone repair in the filed of regenerative medicine.