【摘要】 通过测定pH3.5、不同NaCl浓度下壳寡糖与果胶复合溶液的浊度及Zeta-电位,分析复合溶液宏观/微观状态及浊度滴定过程,结合壳寡糖/果胶聚电解质复合物红外光谱分析、扫描电镜及透射电镜超微结构观察,探讨了NaCl及其浓度对壳寡糖/果胶静电自组装行为的影响.结果表明:NaCl加入会阻碍壳寡糖与果胶分子之间的静电自组装作用,使pH_c、pH_Ф及pH_prep逐渐降低;pH3.5时,随着NaCl浓度增大,复合溶液浊度分阶段下降,溶液逐渐澄清,所形成的PEC减少,并从网状结构变为微小颗粒,甚至达到纳米级（NaCl浓度30 mmol/L及以上）;NaCl低于10 mmol/L时,果胶分子内静电斥力减小,分子链适当软化并弯曲、折叠后与壳寡糖形成大块微粒,而NaCl浓度进一步增加则造成PEC微粒表面Zeta-电位的绝对值增大,微粒间静电斥力加大,果胶分子柔软且易卷曲,包裹壳寡糖形成更小且更分散的微粒;红外光谱分析发现,NaCl添加不改变果胶和壳寡糖之间的作用方式,但可能会影响其强度;推测了不同浓度NaCl下壳寡糖与果胶的自组装作用模式.更多还原

【Abstract】 Effects of NaCl and its concentration on electrostatic self-assembly behavior between chitooligossacharide and pecin at pH3.5 were investigated, through measuring the turbidity and zeta potential of chitooligassacharide/pecin complex solution, and analyzing macroscopic and microscopic state of complex solution and turbidity titration procedure with the study on analysis of ATR-FTIR spectrum and ultrastructure of polyelectrolyte complex by SEM and TEM. The results show that NaCl will hinder the self-assembly interaction between chitooligossacharide and pectin, and lead to a decrease of pH_c、pH_Ф and pH_prep values. With the increasing of NaCl concentration at pH3.5, the turbidity of complex solution decreases in phases, and the solution gradually became clear. Meanwhile, the amount of PEC formed begin to decrease and PEC become into small even nano-particles（NaCl concentration of 30 mmol/L or more） from networks. When NaCl concentration is below 10 mmol/L, the intermolecular electrostatic repulsion of pectin decreases, and pectin chains became properly flexible and can be rolled and folded to form larger particles with chitooligosaccharide. Further increase of NaCl concentration, however, leads to the increase of zeta potential’s absolute value on the surface of PEC particles and electrostatic repulsion interaction among the particles, which result in a better packing of more flexible and coiled pectins with chitooligosaccharide to form more dispersive and less particles. The ATR-FTIR result of PECs shows that the addition of NaCl doesn’t change the interaction ways but may change the interaction intensity between chitooligosaccharide and pectin. Finally, the modes of self-assembly interaction between chitooligosaccharide and pectin at various NaCl concentrations were predicted.更多还原