缩醛化葡聚糖的制备及其酸响应性

Preparation and Acid-Sensitivity of Acetalized-Dextrans

通过缩醛键将正丁基、异丁基、环己基、叔丁基等疏水基团分别引入到葡聚糖主链上,制备了一系列酸敏感性缩醛化葡聚糖。通过核磁分析、紫外-可见光谱测试了缩醛化葡聚糖的结构和酸响应性。结果表明,制得的缩醛化葡聚糖具有相同羟基取代度,且全部为非环状缩醛结构,其酸响应性与缩醛β位的碳原子有关,正丁基修饰的葡聚糖需要更低的pH才能水解,叔丁基修饰的葡聚糖具有更灵敏的酸响应性。

Acid-sensitive acetalized-dextrans had great potential in the field of biomedical applications. However, the influence of substituent group on the acid-sensitivity of acetalized-dextrans was unclear. Herein, a series of acid sensitive acetalized-dextrans were prepared by decorating the dextran backbone with different hydrophocic groups, such as n-butyl,isobutyl, cyclohexyl, or tert-butyl, through the reaction of vinyl ethers with dextran by using pyridinium 4-toluenesulfonate as a catalyst. The structures of these acetalized-dextrans were confirmed by nuclear magnetic resonance(NMR) and Fourier transform infrared spectroscopy(FT-IR), and the hydrolysis products were determined by NMR. The acetalized-dextrans were prepared in a similar hydroxyl substitution degree and all the acetalized groups had a noncyclic structure. The substitution degrees of the n-butyl-decorated, isobutyl-decorated, cyclohexyl-decorated and tert-butyl-decorated dextrans were 49.0%,49.0%, 49.9%, 50.0%, respectively. The acid-sensitivity of these acetalized-dextrans was studied using UV-Vis spectrometry by dispersing acetalized-dextrans into water with different pH values and measuring the transmittance at different time points.The acid-sensitivity of acetalized-dextrans was depended on the type of the β carbon on the acetalized group. The n-butyldecorated dextran required a relatively lower pH to hydrolyze than others, while the tert-butyl-decorated dextran possessed the highest acid-sensitivity among the obtained acetalized-dextrans. This work offered a simple way to adjust the acid sensitivity of acetalized-dextrans by adjusting the type of β carbon on the acetalized group.