Study On The Preparation And Performance Of Porous Drug Loaded Hydroxylapatite Bone Scaffold

Nowadays,due to the prolongation of average life expectancy and the diversification of lifestyles,various bone tissue disorders begin to threaten the health of people of different ages more and more.The artificial bone scaffold not only has good biological adaptability,can provide differentiation and proliferation of osteoblasts,but also can load functional drugs and bioactive substances to solve the complications often associated with bone graft surgery and plant Into the body after the bone regeneration and other issues,has become the best alternative to traditional bone graft materials.This topic prepared a composite drug-loaded bone scaffold,and its basic properties and biological properties were studied.Polylactic acid glycolic acid(PLGA)loaded microspheres were prepared by double emulsion method.The effect of preparation parameters such as PLGA concentration and emulsifying speed on the morphology and drug loading properties of microspheres was investigated.The optimum preparation parameters were as follows: PLGA concentration 30 mg/m L,colostrum emulsification speed 10000 r/min,double emulsion emulsification speed 3000 r/min.The colostrum emulsification speed is the main factor that affects the particle size and drug loading performance of PLGA.The PLGA concentration mainly affects the particle size and drug loading rate of the microspheres,while the rotation speed of the coagulant emulsion will only have a little effect on entrapment efficiency.Nano-hydroxyapatite powders were prepared by chemical co-precipitation method.The phase purity and surface morphologies of the prepared hydroxyapatite powders were investigated by X-ray diffraction and scanning electron microscopy.The sintering parameters of porous hydroxyapatite bone scaffolds was determined by thermogravimetric analysis.After sintering,the relationship between mechanical properties,porosity and other characteristics and ratio of powders to pore-forming agent was studied.The optimal mass fraction of pore-forming agent was 40%,and the values for the compressive modulus and compressive yield strength were 1.06 MPa and 43 MPa,respectively.The hydroxyapatite bone scaffold prepared within this parameter was soaked in dispersion with the drug-loaded microsphere for direct adsorption and immobilization.It can be confirmed that the porous scaffold had a certain immobility on the microsphere.However,there is a clear burst phenomenon in the drug release.Porous hydroxyapatite bone scaffold and PLGA drug loaded microspheres were compounded with sodium carboxymethylcellulose as crosslinking agent.Compared with the drug-loaded bone scaffolds with directly adsorpted microspheres,the burst phenomenon was significantly weakened and the release of the drug sustained for more than 2 weeks in vitro drug release test.After passing the same in vitro release time,there were more PLGA microspheres remained on the drug-loaded bone scaffold with the addition of the crosslinking agent,indicating that the addition of the crosslinking agent can significantly improve the binding strength between the drug-loaded microspheres and the porous scaffold,and enhance its drug release capacity.Through the antibacterial test and osteoblast culture,the best antibacterial property and osteogenic ability was obtained for the porous drug-loaded composite scaffold with 1% concentration of cross-linking agent.This method brings about the integrated effect of drug loading and promoting bone growth.