蛋白质与多糖的静电作用是生物体内一个基本医学-化学现象,是实现自组装的主要驱动力,可利用这种非共价作用设计和构筑理想的微结构。以大豆分离蛋白（Soybean Protein Isolates,SPI）和壳聚糖（Chitosan,CS）为原料,采用浊度法考察了...蛋白质与多糖的静电作用是生物体内一个基本医学-化学现象,是实现自组装的主要驱动力,可利用这种非共价作用设计和构筑理想的微结构。以大豆分离蛋白（Soybean Protein Isolates,SPI）和壳聚糖（Chitosan,CS）为原料,采用浊度法考察了配比、溶液p H值、离子强度和温度对SPI与CS在溶液中相互作用的影响。结果显示,由于p H值影响静电作用强度,从而成为影响SPI与CS相互作用的主要因素,其中,当p H值为5.5~6.6时,SPI与CS可以实现有效结合。在较低的离子强度下,有利于形成具有紧凑结构的CS/SPI聚集体,较高离子强度下聚集体发生解离。蛋白质受热发生变性,多肽链上的疏水氨基酸残基暴露在溶液中,导致与壳聚糖链的疏水作用增强。DLS结果显示,CS与SPI自组装形成了分布均一的纳米粒子,变性后的SPI与CS形成的纳米粒子粒径有所增大,分布均一;经戊二醛交联,粒径有所减小。SEM显示,壳聚糖单层膜表面存在龟裂现象,与SPI形成双层膜后龟裂消失;同时,单层膜厚度约为300 nm,双层膜厚度约为500 nm。展开更多
Optical second harmonic generation (SHG) from the copper tetra-tert-butyl phthalocya-nine (CuttbPc) Langmuir-Blodgett (LB) film deposited on a metal-coated glass slide substrate has been investigated. It is considered...Optical second harmonic generation (SHG) from the copper tetra-tert-butyl phthalocya-nine (CuttbPc) Langmuir-Blodgett (LB) film deposited on a metal-coated glass slide substrate has been investigated. It is considered that the symmetry of the CuttbPc molecule may be broken by the space charge-induced electric field (SCIEF) due to the exchanged charges at the CuttbPc LB film/metal interface. A four-layer model is used to explain the nonlinear optical process in the CuttbPc LB film. The thickness dependence, polarized and incident angle dependence of SHG signal from CuttbPc LB films are calculated. The results of calculation show a good agreement with the experimental data. It is shown that electrostatic phenomena at the interface is correlated closely with SHG signal, and the SHG measurement is also a helpful tool for the detection of the space charge field at the interface.展开更多
文摘Optical second harmonic generation (SHG) from the copper tetra-tert-butyl phthalocya-nine (CuttbPc) Langmuir-Blodgett (LB) film deposited on a metal-coated glass slide substrate has been investigated. It is considered that the symmetry of the CuttbPc molecule may be broken by the space charge-induced electric field (SCIEF) due to the exchanged charges at the CuttbPc LB film/metal interface. A four-layer model is used to explain the nonlinear optical process in the CuttbPc LB film. The thickness dependence, polarized and incident angle dependence of SHG signal from CuttbPc LB films are calculated. The results of calculation show a good agreement with the experimental data. It is shown that electrostatic phenomena at the interface is correlated closely with SHG signal, and the SHG measurement is also a helpful tool for the detection of the space charge field at the interface.
