The Preparation Of Chitosan Crosslinked Microsphere

Microspheres is one of the important direction of current research of drug preparation.Microspheres can reduce the degradation rate of drug and improve the stability of the drug.A single crosslinking agent has good slow release preparation of microspheres,but it can't effectively controlled release.5-Fluorouracil loaded microspheres were prepared by genipin and vanillin complex crosslinking agent in this paper.The release ratio of microspheres was controlled by adjusting the ratio of crosslinking agent.In our study,the preparation of microspheres for single crosslinking agent was first screened.On the basis of this condition,the optimal conditions for the preparation of microspheres were determined.Finally,5-fluorouracil was added to prepare the drug-loaded microspheres.The maximum loading capacity of microspheres was of 2.97%and the encapsulation effciendy was of 20.27% by determination with HPLC.The prepared microspheres were characterized by SEM to show a good dispersibility and uniform particle size distribution with a range of about 10-20 ?m.FT-IR spectra showed that genipin and vanillin were both cross-linked to chitosan.Study of swelling properties showed that the microspheres prepared with different ratio of crosslinking agent had different swelling ratios resulting in that the microspheres prepared by different proportion had different release ratios.XRD analysis of prepared microspheres showed that successful cross linking of microspheres.The results of DSC-TGA confirmed that5-fluorouracil is in the microsphere and the stability of 5-fluorouracil is improved.The release ratio of 5-fluorouracil loaded microspheres was studied by reference to the existed national standard.The release result showed that the cumulative release rate of microspheres in pH3.6 buffer solution was of 97.2% and of 94.2% in pH7.4 buffer solution within 24 h.Therefore,the release rate of microspheres can be controlled by adjusting the ratio of complex crosslinking agent.The stability of microspheres under high temperature,high light and high humidity conditions was studied and the result showed that the prepared 5-fluorouracil loaded microspheres had good stability.