Preparation of Controlled-release PLA Microspheres Loading Methylsulfonylmethane and Its Biological Activity

Polylactic acid (PLA) microspheres carrying methylsulfonylmethane (MSM) were prepared by membrane emulsification. The effects of membrane pore size, stirring speed and MSM concentration on microspheres morphology, size, drug loading and in vitro release, as well as cell biological activity were studied using environmental scanning electron microscope(ESEM), inductively coupled plasma atomic emission spectrometer( ICP-AES), in vitro culture of MC3T3-E1 cell and 3-(4,5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide(MTT) method. The study will provide references for the study of the long-acting release agent of MSM. The results showed that the drug-loaded microspheres prepared with membrane emulsification were typical spherical with smooth surface and the internal porous structure. The size and morphology of the microspheres could be affected by membrane pore size, stirring speed and MSM concentration. The drug-loaded microspheres prepared with the membrane pore size of 5.1 mu m and a stirring speed of 500 r/min were more uniform in size than others. When the mass fraction of MSM solution was 8.6%, the drug loading of microspheres could be up to 77.43%. The in vitro release rate of MSM could be sped up when the membrane pore size was reduced and the MSM concentration was increased, but the initial burst release for all samples was not obvious, and it reached up to 89.2% after 10 d. The cell experiments showed that cell proliferation of MC3T3-E1 was improved at 7 d cell culture using MSM-loaded microspheres with the membrane pore size of 5.1 mu m and MSM mass fraction of 8.6%. The research indicates that the PLA/MSM drug-loaded microspheres has good controlled release characteristics and biological activity, which can be used as a long-acting release formulation of MSM for the treatment of osteoarthritis and application in bone and cartilage tissue engineering.