Preparation And Characterization Of Chitosan/MMT Microspheres

The drug-loaded microspheres made by biodegradable polymer possess broad prospects for application as drug-carrier in medical field. Chitosan(CS) can be utilized as a new kind of drug-carrier, for its good biodegradability, biocompatibility and nontoxic, Montmorillonite (MMT), a kind of typical layered silicate minerals, having good biocompatibility,non-toxic and side effects, has been widely used in medicine fields. MMT modified chitosan microspheres can improve it's swelling performance and mechanical properties, avoiding the drug release process of microspheres in the "burst release" effectively and improving the release effect. Aspirin(ASP),is widely used as antipyretic, analgesic and anti-inflammatory drugs, which prossess a short half-life, but a stimulating effect on the stomach, It's necessary to make sustained-release preparation, to extend the duration of drug efficacy.A series of chitosan microspheres was prepared by emulsion cross-linked polymeization with chitosan as monomer and glutaraldehyde as cross-linking agent. The preparation of chitosan microspheres was optimized by utilized orthogonal analysis. The montmorillonite was modified used the cetyltrimethylammonium bromide (CTAB) and two kinds of different molecular weight chitosan. Chitosan/montmorillonite composite microspheres were prepared. The microspheres size and distribution, the swelling properties of microspheres were characterized. The drug-loaded composite microspheres were prepared. The encapsulation efficiency, drug release rate and the performance of drug release were tested. The main contents and conclusions are as follows:(1) The best process conditions of chitosan microspheres preparation obtained by quadrature analysis are:the concentration of acetic acid 3%, the ratio of water-oil 1:3, the content of span 80 50 mg/L;the content of glutaraldehyde 14.58 mg/L. The chitosan microspheres prepared by emulsion cross-linked have relatively narrow effective average particle size and the particle size distribute range from 500 nm to 700 nm. Chitosan microspheres reached the swelling equilibrium within 30 min nearly, the equilibrium swelling rate was higher in acidic solution;(2) The layer spacing of montmorillonite modified by CTAB increases from 1.46 nm to 1.92 nm, the layer spacing of MMT modified by LCS increased to 1.91 nm; The introduction of modified MMT made the effective size of chitosan microspheres smaller, the modification effect of MMT could also affect the microsphere size; The introduction of modified MMT makes the initial swelling rate and the equilibrium swelling ratio of chitosan decreased. The content of MMT and the modification effect of MMT have an impact on the swelling properties.(3) The rate of microspheres and the drug encapsulation efficiency decreased with the clay content increases. The initial release rate and the maximum amount of drug released of chitosan/MMT decreased with the content of MMT induced increased. The initial releasing of microspheres complied with swelling controlled mechanism, the later behavior of microspheres complies with diffusion controlled mechanism.