香草醛交联的壳聚糖微囊的制备及表征

Preparation and Characterization of Chitosan Microcapsules Crosslinked by Vanillin

将壳聚糖溶液分散于葵花籽油中,以Span-80为乳化剂,搅拌形成油包水乳液,加入香草醛的丙酮溶液进行交联,得到微囊.扫描电镜显示微囊呈圆整的球形,表面致密,内部有空隙.FT-IR光谱和XRD光谱证实壳聚糖的氨基与香草醛的醛基的交联作用和丙酮的脱水作用是壳聚糖液滴固化成形的原因.以萘普生为模型药物制备了载药微囊.结果表明,壳聚糖的脱乙酰度增加,粘均分子量减小,香草醛的用量增加,则微囊的产量、包封率和载药率增加,而药物的释放速率减小.脱乙酰度为96.3%、粘均分子量60.5万的壳聚糖,以醛基/氨基为3.75:1(摩尔比)与香草醛交联制得的载有萘普生的微囊,在含有0.5g/L溶菌酶的模拟结肠环境的释放介质中在10h内可完全释放药物.

Chitosan microcapsules crosslinked with vanillin were prepared by emulsification-crosslinking method. After the chitosan aqueous phase was emulsified into the sunflower oil containing Span-80 as emulsifier by stirring to obtain microdroplets, vanillin solution was added to crosslink the microdroplets. Acetone, the optimal solvent of vanillin, was chosen by comparing the formation and shape of chitosan microcapsules. SEM photographs showed that chitosan microcapsules were spherical and had compact surface and interstitial inner structure. FT-IR and XRD spectra showed that the formation mechanism of chitosan microcapsules was due to the crosslinking reaction between amino groups from chitosan and aldehyde groups in vanillin and the dehydration of chitosan microdroplets by acetone. The influence of the degree of deacetylation （DD） and viscosity-averaged molecular weight （My） of chitosan and the amount of vanillin on the properties of the chitosan microcapsules was investigated. It was found that the yield and naproxen content of microcapsules and naproxen loading efficiency increased, while the rate of drug release in vitro decreased, with the increase of the DD and My of chitosan and the amount of vanillin. Chitosan microcapsules prepared with chitosan （DD=96.3%, Mv=6.05×10^5） and vanillin of which the ratio of aldehyde group to amino group is 3.75：1 can be released completely in the pH 5.6 buffer containing 0.5 g/L lysozyme simulating the environment of colon.