Effect Of Drug-Loaded Polylactic Acid Microspheres On Bone Cement

Polylactic acid has the advantages of good biocompatibility,degradability and adjustable physical and chemical properties.The combination of drug loaded polylactic acid microspheres and PMMA bone cement can build a local drug loading system that can repair bone defects after surgery and continue to play its role,and can provide a new means of orthopedic treatment.Firstly,the optimal preparation conditions of pla microspheres were obtained by response surface methodology.the drug loaded pla microspheres with high drug loading and encapsulation efficiency were successfully prepared by emulsion solvent evaporation method.The effects of the dosage of rifampicin on the physicochemical properties of PLA microspheres were studied in detail.Finally,the drug loaded microspheres were added to PMMA bone cement to prepare PMMA bone cement composites that can slowly release drugs.In this paper,drug loaded polylactic acid microspheres were characterized by a series of tests such as particle size,SEM,infrared,in vitro release,and antibacterial experiments.The curing time,SEM,infrared,XRD,BET,compressive strength,and dynamic mechanical properties of drug loaded microspheres composite bone cement were studied in detail,and their in vitro drug release and antibacterial activities were evaluated.The results showed that the appearance of PLA microspheres with different rifampicin dosage was spherical and the surface of the microspheres was porous.With the increase of rifampicin dosage,the particle size,drug loading,encapsulation efficiency and in vitro release of polylactic acid microspheres gradually increased.The particle size of polylactic acid microspheres with the dosage of 100 mg rifampicin reached 27.02 um,the drug loading and encapsulation efficiency reached 34.60% and 40.59% respectively,and the in vitro release rate reached 71.20%,with the best bacteriostatic effect.At the same time,the study on the influence of polylactic acid microspheres with different drug loads on the properties of bone cement showed that the drug loaded polylactic acid microspheres were uniformly dispersed in PMMA bone cement,FTIR and XRD analysis did not find the displacement of the characteristic peak,and no new absorption peak appeared,indicating that no new chemical bond was formed in the process of compounding bone cement with polylactic acid microspheres with different drug loads,and the hydration reaction of PMMA bone cement was not changed.With the increase of drug loaded PLA microspheres,the porosity of PMMA bone cement increased,the curing time prolonged,and the mechanical properties decreased.The curing time of 30% RPMs PMMA composites is up to 90 min,and the compressive strength is 1.81 MPa.In addition,DMA results showed that the glass transition temperature was the highest,the rigidity strength decreased,the flexibility increased,and the antibacterial activity was the best.