木质素磁性纳米颗粒的构建机制及应用研究

The crisis of resources shortage changes more and more serious in China. Expanding the application of lignin, realizing its scale-utilization, is an important way to alleviate the crisis. Currently, the use of lignin is mainly in low-value, which is a waste of this renewable resource. Up to now, there is no report that lignin is used as magnetic materials. In order to promote the extra-value application of lignin, innovative research is launched on the synthesis mechanism and the application of lignin magnetic nanoparticles. In this project, the main driving force of the combination between lignin and Fe3O4 nanoparticles is studied with AFM firstly, in order to reveal the factors affecting the particle size of lignin magnetic nanoparticles. Then the control mechanism of the particle size, the surface charge and the surface functional groups of lignin magnetic nanoparticles is constructed through the synergy of the lignin structure and the solution conditions. Based on the above research, lignin magnetic nanoparticles with the particle size range of 50~200 nm are prepared under the optimized process. Furthermore, the performance of these magnetic nanoparticles in the fields of adsorption separation, enzyme immobilization and targeting pharmaceutical is evaluated. At the same time, to establish the relationship between the structure and the performance of the magnetic nanoparticles, the mechanism of the surface charge, the surface groups and the particle size on the performance of the nanoparticles is explored. The main driving force of the formation of lignin magnetic nanoparticles, as well as the control mechanism of the surface charge and the surface functional groups of lignin magnetic nanoparticles, is the key scientific issue required to be addressed in this project. The completion of this project will open up new application field for lignin, increase its extra-value, and finally contribute to the strategic objectives of the social sustainable development.

我国面临资源短缺的危机。扩大木质素用途，实现资源化利用，是缓解资源短缺的重要途径。目前木质素以低值利用为主，尚未有用作磁性材料的报道。为了提高木质素的应用附加值，本项目围绕木质素磁性纳米颗粒的制备与应用展开研究。项目以木质素为主要原料，首先利用AFM研究木质素与Fe3O4纳米粒子结合的主要驱动力，通过木质素结构与溶液条件协同，构建木质素磁性纳米颗粒粒径、表面电荷、表面官能团的控制机制，优化工艺，制备粒径范围为50~200 nm的木质素磁性纳米颗粒。进一步探索木质素磁性纳米颗粒在吸附分离、酶固定化、靶向药物领域的应用性能，揭示表面电荷、表面官能团、颗粒形貌对应用性能的作用机理，建立木质素磁性纳米颗粒的构效关系。其中，阐明木质素结合Fe3O4纳米粒子的主要驱动力，构建木质素纳米颗粒表面电荷密度及官能团的控制机制是项目要解决的关键科学问题。本项目将为木质素开拓高值应用领域，促进社会可持续发展。

积极利用可再生资源是人类社会可持续发展的必然选择，而资源短缺已成为制约我国经济可持续发展的重大战略问题。.木质素是地球上含量仅次于纤维素的生物质资源，但目前其商业化利用率不足10%，大部分被焚烧丢弃。寻找木质素高附加值利用的途径，是实现我国可持续发展战略目标的迫切需求。.本项目的主要研究内容包括利用AFM探讨木质素与Fe3O4结合力、木质素磁性纳米颗粒的制备及表征、揭示木质素磁性纳米颗粒在不同领域的应用性能及构效关系三部分内容。项目的主要研究结果如下：.(1) Fe3O4和木质素之间主要靠静电吸引、氢键和范德华力结合。pH=4.8时，Fe3O4和木质素磺酸盐主要依靠静电吸引结合。pH=6.8时，静电吸引力显著减弱，此时Fe3O4与木质素之间的结合力主要是氢键和范德华力。.(2) 以氨水作为沉淀剂和亚铁盐与铁盐混和溶液、碱木质素溶液一起反应可制备纳米级木质素基碳磁性纳米颗粒。该纳米颗粒平均粒径为73.9nm，表面具有丰富的孔径为11.9nm的介孔。优化的条件下，该纳米颗粒对甲基橙的吸附率随用量的增加而增大。而随吸附温度的升高，吸附率及吸附容量则均降低。吸附反应基本在120~180min内达到平衡，符合伪二级动力学模型方程，且为放热熵减的自发过程。.(3) 季铵化木质素与Fe3O4的前驱体可反应生成pH响应型木质素基磁性纳米粒子。优化条件下，该磁性纳米粒子对纤维素酶的固定化率达到55.52%。当pH=6.8时，纤维素酶的最大脱附率为68.27%，相对酶活可保留80%。.(4) 采用反相乳液交联法对胺化木质素ALS与磁性Fe3O4进行复合可制备磁性纳米药物载体ALS/Fe3O4，该载体的粒径分布在68.7~229.8nm之间。载药粒子对阿霉素的平均载药量为12.41%。pH=4时，阿霉素的释放量为45.10%；pH=7.4时，药物释放量为20.93%。.本项目将木质素与磁性粒子结合，赋予木质素磁性特征，并应用在吸附分离、酶固定化、靶向医疗等领域。项目不仅可显著提高木质素应用附加值，实现其资源化利用，而且对缓解资源短缺矛盾，促进我国可持续发展战略目标实现都具有重要的科学意义和社会价值。