Structural Performance And Biocompatibility Study Of Drug Loaded Medical Porous Magnesium

Porous metal have potentially broad application in the field of biological implant materials.But the method of preparation of porous metal biomaterials still exist some problems,such as complex production process,high cost and difficult precise controlled pore size and porosity.In this paper,using pure magnesium and TA1 titanium wire as raw material and pore-forming agent method,porous magnesium materials with different pore sizes and different porosities were fabricated.The structure characteristics and mechanical properties of the porous magnesium were studied.In order to improve the corrosion resistance,the porous magnesium was treated by different surface treatment way.The corrosion resistance of surface treated porous magnesium was studied in simulated body fluid.In order to prevent postoperative infection,gentamycin sulfate was loaded into the pores of porous magnesium respectively by osmosis method and embedding method.The drug release behaviors of gentamycin sulfate loaded porous magnesium were studied in simulated body fluid.The drug loading capacities,the initial burst release and the effective release time of two drug loaded porous magnesium were contrasted.The biology experiments of porous magnesium were carried out.This study can provide informations for porous magnesium as functional bone repair materials.The pore size and porosity of this porous magnesium can be controlled accurately.The pores in porous magnesium are highly connected.When implanted,the connected pores in porous magnesium can provide channels for bone cell growth and fluid transmission,which is beneficial for prosthesis fixation.The compressive strength of porous magnesium with pore size0.10-0.40 mm and porosity 30%-50%was 60-120MPa,and the elastic modulus was 5-15 GPa.The compressive strength and elastic modulus of porous magnesium reached the level of cortical bone.The corrosion resistance of porous magnesium in Hank's solution is very poor.Fluoride treatment,alkali treatment and micro-arc oxidation treatment can greatly improve the corrosion resistance of porous magnesium.The corrosion resistance time of porous magnesium after fluoride treatment,alkali treatment,micro-arc oxidation treatment were 11 days,6 days and 28 days respectively.After micro-arc oxidation treatment,the corrosion resistance time of porous magnesium with pore size 0.40 mm and porosity 30%reached 44 days.In vitro experiments show that the micro-arc oxidation treatmented porous magnesium has good cytocompatibility and osteoblastic differentiation properties.In vivo experiments show that the porous magnesium exhibited acceptable inflammatory responses and can be degraded and replaced by newly formed bone.The drug loading per unit volume,the amount of drug release at the first 24hours and the effective drug release time of gentamicin sulphate loaded porous magnesium with pore size 0.27-0.40 mm and porosity 30%-50%fabricated by osmose method were respectively 8.5-14.5 mg/cm~3,25%-38%and 7-10 days.The drug loading per unit volume,the amount of drug release at the first 24hours and the effective drug release time of gentamicin sulphate loaded porous magnesium with pore size 0.27-0.40 mm and porosity 30%-50%fabricated by embedding method were respectively 30-50 mg/cm~3,7.3%-9.8%and 21-35days.The drug loading per unit volume of the gentamicin sulphate loaded porous magnesium fabricated by embedding method was more than the gentamicin sulphate loaded porous magnesium fabricated by osmose method.The burst release of the gentamicin sulphate loaded porous magnesium fabricated by embedding method was less than the gentamicin sulphate loaded porous magnesium fabricated by osmose method.The effective drug release time of the gentamicin sulphate loaded porous magnesium fabricated by embedding method was longer than the gentamicin sulphate loaded porous magnesium fabricated by osmose method.The gentamicin sulphate loaded porous magnesium has good antibacterial effect on staphylococcus aureus.