| Objective:Infected bone defects and chronic osteomyelitis is one of the more common diseases in orthopedics,and the difficulty of clinical treatment is increasing,which often consumes a lot of human,material and financial resources,and there are still cure difficulties,resulting in a great impact on the life and work of patients.SF/VANCO/PLGA/β-TCP composite anti-infection artificial bone scaffolds are an optional protocol for treating infected bone defects and have good application prospects.This study investigated the in vitro biological evaluation of composite scaffolds by constructing composite anti infection artificial bone scaffolds,with a view to provide a new alternative treatment option for the treatment of clinical chronic osteomyelitis.Methods: This experiment consisted of three parts1.Preparation and process optimization of vancomycin hydrochloride loaded PLGA sustained-release microspheres: Vancomycin hydrochloride loaded poly（lactic-co-glycolic acid）（PLGA）sustained-release microspheres were prepared by a double emulsion solvent evaporation method.By using drug loading and encapsulation efficiency as evaluation indexes,the effects of PLGA concentration in oil phase,VANCO concentration in internal water phase,PVA concentration in outer water phase and sodium chloride（Na Cl）concentration in outer water phase on drug loading and encapsulation efficiency of microspheres were investigated.Through the orthogonal test to analyze the results of drug loading（DL）,encapsulation efficiency（EE）,drug loading+encapsulation efficiency,the best preparation process was selected.2.In vitro drug release and antibacterial activity evaluation of silk fibroin coated vancomycin hydrochloride loaded PLGA sustained release microspheres: Based on the best preparation parameters and preparation technology selected in the above experiments,the drug-loaded microspheres were produced in batches.The drug-loaded microspheres were coated with three different concentrations（0.1%,0.5%,1%）of silk fibroin（SF）to delay the initial burst release.The experiments were divided into four groups: 0% SF group,0.1% SF group,0.5% SF group,1% SF group,and the microspheres after coating with different concentrations of SF were evaluated by scanning electron microscope,microspheresize,fourier transform infrared spectroscopy,hydrophilicity,in vitro drug release and in vitro antibacterial activity.3.Construction and in vitro biological evaluation of SF/VANCO/PLGA/β-TCP composite anti-infective artificial bone scaffold: β-TCP artificial bone scaffolds with good porosity and mechanical properties were prepared by 3D printing technology.By compounding the 3D-printed scaffolds with drug-loaded microspheres coated with different concentrations of SF,constructed a composite anti-infective artificial bone scaffold material which not only contains VANCO,but also has certain mechanical properties.The relevant properties of the composite scaffolds were clarified by examining their biomechanics,porosity,degradability,biocompatibility,osteogenic activity in vitro.Results:1.Sustained release PLGA microspheres loaded with vancomycin were successfully prepared by a double emulsion solvent evaporation method,and the optimal preparation process parameters of drug loaded microspheres were selected by orthogonal tests: The mass of VANCO invested in inner aqueous phase was 200 mg（200 mg/ml）,the mass of PLGA invested in oil phase was 400 mg（40 mg/ml）,the PVA concentration in outer aqueous phase was 0.5%（5mg/ml）,and the Na Cl concentration in outer aqueous phase was 1%（10mg/ml）.The microspheres exhibited a final drug loading capacity of 24.11% ± 1.72% and encapsulation efficiency of48.21% ± 3.44%,the mean particle size was 97.59μm ± 0.51μm.The microspheres were white powder in naked eye,round and regular in shape under light microscope and electron microscope.2.The successful coating of SF to the surface of drug loaded microspheres was confirmed by scanning electron microscope and fourier transform infrared spectroscopy,and the effect of 0.1% SF coating on delaying initial burst release was significantly better than that of the control group（0% SF group）（p< 0.05）.3.The SF/VANCO/PLGA/β-TCP composite scaffold was successfully constructed.SF coated drug loaded microspheres were well filled in the pores of each group of scaffolds,and the composite scaffolds of each group had good biomechanical properties,porosity,degradability,biocompatibility and osteogenesis.Among them,the 0.5%SF group composite scaffold exhibited the best biocompatibility and osteogenic activity.Conclusion:The SF/VANCO/PLGA/β-TCP composite anti-infection artificial bone scaffold was successfully constructed.After comprehensive evaluation of the properties and biological activities of the four groups of materials,the composite scaffolds of0.1%SF group showed superior anti-infection ability,good hydrophilicity,mechanical properties,biocompatibility and osteogenic activity,which was an ideal anti-infective artificial bone material.However,the experimental results still need further in vivo animal experiments and clinical experiments to verify. |
