使用高脱乙酰度壳聚糖制备了靶向药物载体-叶酸改性壳聚糖微球。首先通过碱法制备了高脱乙酰度的壳聚糖，采用酸碱滴定法和傅里叶变换红外光谱(FTIR)对其结构进行了表征，结果表明，经脱乙酰化处理后的壳聚糖脱乙酰度高达93.8%。然后以高脱乙酰度壳聚糖制备了叶酸改性壳聚糖，创新性地发现用1∶1的二甲基亚砜和水的混合溶剂可以得到壳聚糖和叶酸反应的均相体系。通过不同的改性方案，得到了不同改性程度的壳聚糖，改性程度分别达到了2.60%、5.10%、8.75%和9.49%。最后用三聚磷酸钠交联制备了叶酸改性壳聚糖微球，并用激光粒度仪系统地分析了三聚磷酸钠和改性壳聚糖的用量比例及浓度对微球的粒径、Zeta 电位的影响。研究发现，随着三聚磷酸钠与改性壳聚糖的比值增大，微球的粒径和 Zeta 电位都增大，当比值增加到一定的程度，微球的粒径会快速增加。对三聚磷酸钠和改性壳聚糖加入浓度的研究，发现浓度的增大将导致粒径的增大和Zeta电位的降低。%In this study,chitosan was used for nano-targeted drug carriers preparation.Firstly,highly deacety-lated chitosan was prepared by alkaline process,and evaluated the degree of deacetylation with acid-base titration and FTIR.The results suggested that the degree of deacetylation of chitosan prepared arrived at 93.80%,basically mee-ting the experiment requirements.Then the folic acid modified chitosan was made using the deacetylated chitosan as raw material.The preliminary experiment gave a clue that the water mixed with DMSO at the rate of 1∶1 offered a homogeneous system for the reaction between folic acid and chitosan.After modification process,the different levels of modified chitosan were obtained,and the value achieved 2.60%,5.10%,8.75% and 9.49%,respectively.Final-ly,sodium tripolyphosphate was utilized as a cross-link agent for the further modification of chitosan.After the prepa-ration of the folic acid modified chitosan nanoparticles,the proportion and concentration of sodium tripolyphosphate and modified chitosan were simultaneously studied,focusing on the nanoparticles size and Zeta potential.It was found that with the increasing ratios of sodium tripolyphosphate and modified chitosan,the particle size and Zeta potential of the nanoparticles increased.By studying the influence of sodium tripolyphosphate and the modified chitosan′s concen-tration,we found that the increasing concentration would lead to the enlarging of particle size and declining of Zeta po-tential.
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