聚酰胺胺树形分子的叶酸修饰及其表征

聚酰胺胺（Polyamidoamine，PAMAM）树形分子是一种广泛用于药物载体和基因载体研究的合成大分子．由于肿瘤细胞表面具有大量表达的叶酸受体，在树形分子末端接枝上叶酸分子可以增强该化合物的肿瘤靶向性．通过发散法合成了0到4代乙二胺为核的聚酰胺胺树形分子并进行叶酸接枝修饰．利用红外光谱及紫外-可见光谱分析，对所得到的树形分子-叶酸化合物进行了结构表征．结果表明：以吡啶作为催化剂叶酸接枝效果较好，通过与叶酸紫外吸收标准曲线对比计算，零代树形分子-叶酸共轭化合物的平均接枝率约为31％，一代至四代树形分子-叶酸共轭化合物的平均接枝率分别为28％、36％、15％和10％．

Synthesis and characterization of folic acid-modified polyamidoamine dendrimers

Polyamidoamine （PAMAM） dendrimers are synthetic molecules which are now widely used as vectors in drugs delivery and gene transfer research. Since folic acid （FA） receptor is over-expressed on the surface of tumor cells, the tumor-targeting effect of dendrimers can be improved though grafting folic acid at the terminal of the dendrimer molecules. Ethylenediamine-core PAMAM dendrimers with generation 0 through 4 were synthesized using divergent strategy, and folic acid molecules were grafted onto the dendrimer surface. The obtained dendrimer-FA compounds were characterized by FT-IR and UV-vis spectra. The results show that pyridine is a good catalyst for the folic acid grafting. The grafting ratio of G0-PAMAM-FA is about 31% and the ratios for the grafted G0-G4 PAMAM dendrimers are 28%, 36%, 15% and 10% respectively.