由酪蛋白胶束的超级组装制备纳米或微米粒子研究

Casein can self assemble into core-shell micelles in aqueous media, and the shell consists of hydrophilic chains with a lot of functional groups with charges, which opens a window to prepare functional materials by starting from casein. Lately, when Zn2+ or Cu2+ is added to casein/ammonia aqueous solution, and then heated to above 100 C, hierarchically architectured ZnO or CuO microparticles are obtained. The microparticles with dimensions ranging from 600 nm-2.5 μm are built of 30-50 nm nanoparticles. If casein and Cu2+ are dissolved together in dilute HCl solution, and then reducing agent is added, nano-wires and nano-particles can be been prepared. For the monovalent Ag+, no micro but only nano particles are obtained under identical condition either in alkali or acidic casein solution. The results indicate that casein micelles play a key role to induce the formation of nano and/or microparticles. Therefore, it is planned to investigate which types of micelles of casein are formed under different environmental conditions such as different pH, temperature and ionic strengths. The main experimental methods which will be applied in this context are light scattering and viscometry, where intrinsic viscosities will be determined by means of a new evaluation procedure (which can also be applied for polyelectrolytes in the absence of extra salt). Then, the bindings of casein micelles with mono- and multivalent metal ions, such as Ag+, Cu+, Zn2+, Cu2+, Al3+ and Cr3+, will be studied in order to learn the formation of super assembly of casein micelles. Following, the casein micelle templated nano- or micro-scale super-assemblies will be prepared by conversion of the micelle-surface neighboured metal ions into metal oxide or pure metal. Finally we plan to investigate the suitability of the hierarchically architectured ZnO microparticles in field of the dye-sensitized solar cells.

酪蛋白在水中自组装成为纳米尺度的胶束，胶束表面分子链含有大量官能团，为其功能化应用提供了可能。前期研究结果发现，将Zn2+或Cu2+加入酪蛋白氨水溶液中，经加热后得到由30-50 nm微粒构建的600 nm-2.5 μm的多级结构ZnO或CuO微球；将Cu2+加入酸性酪蛋白溶液中，经还原反应得到纳米线；将Ag+加入酸性或碱性酪蛋白溶液中，反应后却总得到银纳米粒子。以上结果说明，酪蛋白起到了纳米粒子形成及进一步生长形成多级结构材料的关键性调控作用。为此，本项目拟采用我们新近建立的聚电解质特性粘数测定方法，研究影响酪蛋白胶束形态的控制因素，尤其是研究不同价态金属离子与酪蛋白的结合作用，掌握多价态金属离子存在下酪蛋白胶束的超级组装行为；掌握酪蛋白胶束及其超级聚集体诱导上述纳米或微米多级结构的形成机理，构建制备多级结构材料的新方法；并开展多级结构ZnO微球作为染料敏化太阳能电池电极材料的应用研究。

按照“项目计划书”和“项目申报书”中所述计划和内容，较好地完成了本项目的研究工作。（1）采用聚电解质粘度测定新方法较为详细研究了酪蛋白的粘度行为。通过对数粘度对聚合物浓度作图，由曲线的起始斜率可获得聚电解质的特性粘数，这首次采用这种新方法研究球状蛋白质或聚集体胶束的溶液性质；该方法也适用于不带电高分子体系。研究发现酪蛋白、牛血清白蛋白、聚苯乙烯磺酸钠等聚电解质在外加盐存在下特性粘数降低，但球状蛋白或酪蛋白胶束的降低较链式聚电解质小，这是由于球状蛋白质分子或胶束内的水分子被排除出来引起尺度降低占主导作用所致。（2）以酪蛋白胶束、壳聚糖、海藻酸钠、纤维素分子为基础，制备了多级结构ZnO、磁性壳聚糖纳米复合物、超细Fe3O4纳米粒子、离子印记凝胶、纳米纤维素诱导有机小分子或高分子取向结晶，构建了一系列纳米材料制备的新方法；对所得材料进行了详细表征并探索了它们的应用前景；由此说明，天然高分子富含各类功能基团，对它们的改性和利用能制备高值化的各类功能材料。（3）通过在沉淀剂蒸气气氛中挥发聚合物溶液溶剂的蒸气诱导相分离法，制备了具有多孔且超疏水性的三维网络涂层膜材料，发现其孔性能与超疏水性受聚合物的构象、溶剂和沉淀剂类型、以及它们的扩散速度调控；另外，以这种三维多孔材料为模板，通过在制备体系加入无机纳米材料或前驱体，制备了多种石墨烯基复合材料如Cu2O/rGO、MoS2/rGO、C/TiO2/rGO等，详细表征了它们的结构与性能，发现最终材料优良吸附和电化学性能等的关键是该三维多孔材料模板提供的多孔结构，石墨烯能提供高导电性能，其它无机纳米材料提供预期的各种功能。（4）在本项目支持下，已正式发表论文9篇、已接受待发表1篇，已投稿和修改中论文6篇，正整理拟投稿论文3篇；获授权发明专利5件、已申发和公开发明专利2件；开展相关学术交流与合作，包括在国际学术会议报告7篇次，国内会议报告3篇次。