摘要
由于双亲性聚合物的自组装行为受环境因素的控制，以胆固醇3-半琥珀酸酰氯与氧化葡聚糖反应，得到胆固醇疏水改性葡聚糖聚醛（CMDA），通过改变环境pH值，控制氧化葡聚糖醛基与烯醇基的转变，从而改变CMDA分子间相互作用，以荧光光谱、表面张力和浊度等方法研究分子间作用力的改变对双亲性聚合物自聚集行为的影响．结果表明，CMDA在水中自组装形成纳米自聚集体，在pH=4．0和pH=10．83溶液中CMDA的临界聚集量浓度值分别为0．002mg／mL和0．005mg／mL，比中性环境中的临界聚集量浓度（0．02mg／mL）低了1个数量级．3种pH条件下自聚集体溶液表面张力具有共同的变化趋势，但在酸性与碱性条件下具有更好的表面活性．在很宽的pH范围内（4．4～10．5）溶液浊度保持稳定，而当pH小于4．0时浊度快速增大，并在4．0时达到最高值，动态光散射粒径测试验证了浊度测试结果．
Self-assembly behavior of amphiphilic copolymer is sensitive to environment. In this paper, cholesterol hydrophobic-modified dextran polyaldehyde （CMDA） was synthesized by esterification of dextran polyaldehyde with cholesterol 3-hemissuccinyl chloride. The influence of pH on self-assembly behavior of CMDA was investigated by using fluorescence spectra,surface tension ,turbidity and dynamic light scattering. Since the aldehyde groups can be reversibly converted into enol groups depending on acidity and alkalescence of environment, the inter-and intra-molecule interaction of CMDA can be adjusted by changing the pH of medium, as a result, the self-assembly behavior of CMDA may be altered. The results indicate that CMDA is self-assembled into nanoparticles with different critical aggregation concentrations in water, depending on the pH of medium. Critical aggregation concentrations of CMDA are 0. 002 mg/mL and 0. 005 mg/mL, under pH =4.0 and 10.83, respectively, which are about one order of magnitude lower than neutral condition （ critical aggregation concentration is 0.02 mg/mL）. Surface tension in three pH conditions has the same tendency, but surface activity is better in acidity and alkalescence solutions. Turbidity is stable in a large range of pH values （4.4-10.5） , but it increases quickly when pH is below 4.0, and reaches the highest point at pH = 4.0, dynamic light scattering validates turbidity measurment results.
出处
《天津大学学报》
EI
CAS
CSCD
北大核心
2006年第11期1384-1390,共7页
Journal of Tianjin University(Science and Technology)
基金
国家自然科学基金资助项目(50573056)
关键词
胆固醇疏水改性葡聚糖
自聚集
PH值
表面张力
cholesterol hydrophobic-modified dextran polyaldehyde （CMDA）
self-assembly
pH value
surface tension
