Preparation And Drug Release Mechanisms Of CS/β-TCP Composite Microspheres Loaded Drug

Among bone defect repaired procedure, it is an inevitable problem that infection leading to repaired failure for the bone doctors. Not only patients would suffer from pain again but also got mad in spirit. The infection generally was happened owing to no clearly disinfection or implant brought in. To prevent bone defection from infection, oral antibiotic was suggested by doctors which will create an issue——hurt people’s organ and no security. In this article an novel drug-loading vancomycin (Van) CS/β-TCP composite microspheres was prepared, which is purpose for reduce infection in bone repaired.Chitosan (CS) and β-tricalcium phosphate ((3-TCP) were applied widely in bone defect repaired scaffolds and drug controlled-released system for their excellent biocompatibility, nontoxic and good biocompatibility. The CS/β-TCP microspheres were prepared using water-in-oil (w/o) emulsion cross-linking method. This method had some advantages of sustain technique, operating handy, low equipment required, suitability of lab and factory. The CS/β-TCP composite microspheres were observed by scanning electron microscopy (SEM). It can be concluded that all microspheres were of a good spherical shape and size distribution concentrated. The loading efficiency of Van in CS/β-TCP microspheres can be30%at most, encapsulation efficiency be90%detected by Ultraviolet-Visible absorption Spectra (UV). The in vitro release property was detected with simulated body fluid (SBF)37C℃and release curves illustrated that vancomycin release4weeks longest.Van loaded in CS/β-TCP microspheres mechanism was discovered by Fourier transform infrared spectroscopy (FTIR). The results showed that amide exist inside of Van and CS molecules which cross link with glutaraldehyde. Van was enfolded in net matrix cross-linked by CS. It is believed that Van molecule is larger than CS and interspace hindrance larger too, meanwhile amide density smaller than CS, which leaded to Van cross-linking slower than CS molecule with glutaraldehyde. Some of Van may cross-link incompletely and some would be encapsulated in CS/β-TCP microspheres though physical attraction.In vitro Van release mechanism was study by SEM mainly. and the release curves were imitated with release kinetics equation. The results illustrate that Van release into SBF depended on dissolved-diffusion and swollen-diffusion mechanism. At first, when CS/β-TCP microspheres contacted with SBF solutions, Van existed in surface of microspheres by physical absorption microspheres were dissolved. And then, water molecules permeated into microspheres inside though micro tubing on the surface of microspheres and Van inside dissolved, uncross-linked initially which was faster than CS. CS/β-TCP microspheres began to swell after water permeating inside and some microspheres would split at the thin shell for water swollen. Van and CS dissolved constantly from shell to core. Because CS dissolute in water solution, dissolved CS would form gel film holding Van bake inside which got control-release function at the end of release. The release curves were imitated that at the first bursting stage release curves was in line with Highchi equation, and at the end control-release stage corresponded with first order kinetics equation. Drug delivery matrix fabrication would be guided and release property be improved by studying on release kinetics.