【作者】 原霞；

【导师】 王飞镝；

【作者基本信息】 广东工业大学 ， 化学工程， 2012， 硕士

【摘要】 大豆蛋白是一种优质的天然聚合物原料,它既有营养性,也具备良好的功能性。埃洛石纳米管(halloysite nanotubes,简称HNTs)是一种天然的多壁纳米管状的硅酸盐纳米材料,具有良好的分散性,与聚合物制成复合材料,可使聚合物具有更好的结构和性能。与大豆蛋白一样,埃洛石也是取自天然的、无毒的天然材料。用埃洛石与天然蛋白质作用,制备复合凝胶材料,是改善蛋白质功能,获得无污染、无毒性复合材料的重要方向。本文以大豆分离蛋白质(SPI)为反应原料,与埃洛石纳米管(HNTs)复合,适当添加戊二醛(GTA)交联剂,制备出SPI-HNTs纳米复合凝胶材料。研究了SPI-HNTs纳米复合凝胶材料的溶胀性能(SR)和破裂强度(RS)。结果表明：当温度为65℃、pH值为1、m(HNTs):m(SPI)为1：20,GTA%为0.6时,凝胶的平衡溶胀率(SR)最大为13.35g/g；考察了无机盐NaCl对于凝胶的平衡溶胀率的影响,结果发现,NaCl浓度从0.001mo1/L增至0.5mo1/L,凝胶溶胀率从15.81g/g降为5.81g/g。不同的干燥方式对复合凝胶平衡溶胀率也有显著的影响,研究发现,红外干燥方式制得的凝胶溶胀率最佳。凝胶的破裂强度RS受m(HNTs):m(SPI)、GTA%(即GTA%=m(GTA)/m(SPI+HNTs))等因素的影响,m(HNTs):m(SPI)一定程度增大有利于破裂强度的增大,原因与HNTs和SPI分子链上极性键有关,体系内部的相互作用力得到调整,使分子链变得规整,但是HNTs用量过大,反而使凝胶的RS降低,有可能是SPI分子链被吸附于HNTs纳米管的表面,使SPI分子链运动受到抑制,形成的凝胶网络承受力减弱。用综合热重分析仪(TG)和扫描电子显微镜(SEM)对HNTs-SPI纳米复合凝胶材料的热稳定性和断面形貌进行了研究。TG结果显示纯大豆分离蛋白质凝胶的失重为50%时的温度是371.95℃,而HNTs-SPI纳米复合凝胶是393.16℃,反映出复合凝胶材料的热稳定性高于纯大豆蛋白凝胶。SEM图像可见,纯SPI凝胶细微结构为均相,添加HNTs的凝胶呈两相分布状态,HNTs以单管形式均一的分散在SPI基体中,结构的细腻程度与m(HNTs):m(SPI)有关。经过红外干燥的凝胶断面要比经鼓风干燥、真空干燥的更加平整。对凝胶的流变性进行了研究,并讨论了化学交联剂戊二醛(GTA)的添加和HNTs含量对凝胶流变性的影响结果显示,加入GTA的化学交联型SPI-HNTs纳米复合凝胶的弹性模量(G’)要明显的高于未加入GTA的SPI-HNTs纳米复合凝胶,而损耗角正切值(tanδ)小于未加入GTA的SPI-HNTs纳米复合凝胶,这说明GTA交联作用增强了凝胶网络的抗宏观应变能力；m(HNTs)的变化也影响凝胶的储能模量(G’)和损耗角正切值(tanδ),反映出适量的HNTs调整了SPI和HNTs的分子内和分子间作用力。通过SPI-HNTs纳米复合凝胶与合成的无化学交联剂的SPI-HNTs纳米复合物流变性能对比和FTIR分析,揭示了埃洛石与大豆分离蛋白质分子形成了复合氢键,建立了次级交联网络。采用药物溶液浸泡物理吸附法,制备HNTs-SPI纳米复合凝胶载药凝胶。探讨了载药凝胶体外释放性能,结果发现：在不同的pH(为1.7、4.4、7.2)缓冲液中,凝胶的释药行为总体上表现为先快后慢,酸性介质(pH为1.7、4.4)中累积释药率大于近中性介质(pH为7.2);不同浓度的氯己定溶液制的载药凝胶累积释药率随m(HNTs):m(SPI)的增大而减小,这与HNTs纳米管本身的结构性质有关,被吸附于埃洛石纳米管内的氯已定分子中的亚氨基与埃洛石管内的羟基可形成氢键作用,阻碍药物释放出来对药物释放;当n(HNTs)保持一定范围,载药凝胶累积释药率随氯己定溶液浓度的增大而降低,即低浓度的氯已定溶液制备的载药凝胶更容易释放吸附的药物。更多还原

【Abstract】 Soybean protein is a kind of important plant protein resources, and its applications in food and medicine not only depend on its nutrition, but also rely on its function. Halloysite nanotubes are a kind of aluminosilicate clays with hollow nanotubular structure mined from natural deposits, and own a good dispersion property in polymer materials. Halloysite nanotubes are also non-toxic natural materials as soybean protein. At present, the research on halloysite nanotubes added as compositing agent in polymer(such as protein) to prepare functional gel material is an important direction.SPI-HNTs nano composited gel materials were prepared by compositing soy protein(SPI) with halloysite nanotubes(HNTs), cross-linking with glutaraldehyde(GTA). The swelling property and rupture strength of SPI-HNTs nano composited gel materials were researched. The results show that:the highest equilibrium swelling ratio (SR) of the gel is13.35g/g at65℃,when pH value is11, m (HNTs):m (SPI) is1:20, GTA%is0.6respectively. The equilibrium swelling ratio (SR) was effected by the inorganic salt. The equilibrium swelling ratio (SR) is from15.81g/g to5.81g/g when the concentration of NaCl was from0.001mol/L to0.5mol/L. Different drying methods have a significant effect on swelling ratio of gel. Equilibrium swelling ratio of gels by infrared drying is the highest. Rupture strength(RS) of gel is effected by m(HNTs):m(SPI) and GTA%(GTA%=m(GTA)/m(SPI+HNTs)) and so on. Rupture strength(RS) increase with increase of m (HNTs):m (SPI). It may be relevant to polar bond between HNTs and SPI, and internal forces of gel system was adjusted which made the molecular chain become neat. However, increasing of m(HNTs) making RS of gel reduced. The reason is that SPI molecular chain is adsorbed on the surface of HNTs nanotube, and make the SPI molecular chain movement restrained, hydrogel network endurance abating.SPI-HNTs nano composited gel were charaterized by TG and SEM. The TG result showed that50%weight loss of pure soybean protein gel is observed at371.95℃, while50%weight loss of SPI-HNTs nano composited gel is at393.16℃. Addition of HNTs improved the thermal stability of composited gel. The picture of SEM showed that pure soy protein gel present a uniform single-phase structure; composited gel added with a few amount of HNTs present a two-phase distribution structure, and HNTs nanotubes dispersed in the matrix of SPI uniformly; the fine structure showed a little different at different ratio of m(HNTs):m (SPI). The section morphology of gel after infrared drying was more smooth than that after the drum wind drying and vacuum drying.The rheological properties of the gel were investigated, and the effect of chemical crosslinking agent glutaraldehyde (GTA) and the amount of HNTs on the rheological properties of gels were also discussed. The result showed elastic modulus (G’) of GTA crosslinked SPI-HNTs gel was higher than that of SPI-HNTs compound without GTA. While tangent loss angle (tan δ) of GTA crosslinked SPI-HNTs gel was less than that of SPI-HNTs compound without GTA; the reason is that crosslinking function of GTA enhancing the anti-macro strain of gels networks; the amount of HNTs in gels also affect the elastic modulus (G’) and tangent loss angle(tanδ), because the appropriate amount of HNTs added adjusted the interaction intro-and between SPI and HNTs molecules. By comparing the rheological properties and FTIR spectrum of SPI-HNTs nano compound without GTA crosslinking and with GTA crosslinking, the results showed that the the composited hydrogen bonding is formed and the secondary network is established between halloysite nanotubes and soybean protein.The SPI-HNTs nano composited gel with drug-loaded was obtained in physical absorption method by immersing in the drug solution. The drug-released properties of the gels were discussed. The results show that the accumulative release ratio(CR) of the gel is fast in the first,then slow in different buffer(pH1.7, pH4.4and pH7.2), and the accumulative release ratio (CR) was higher in acid medium(pH1.7and pH4.4) than in pH7.2buffer; the accumulative release ratio (CR) of gels with drug-loaded which are obtained in different CHI) concentration decrease with increase of m(HNTs):m(SPI).This may be relevant with the structure of halloysite nanotube itself, because strong the hydrogen bonding interaction was produced between CHD and hydroxyl in the tubes of HNTs. The strong interaction obstructs CHD to be released. The accumulative release ratio (CR) decreases with increase of CHD concentration. It explain that the SPI-HNTs nano composited gels with drug-loaded which are prepared in low concentration of CHD are more easy to release the medicine.更多还原