毛竹细胞壁纤丝聚集体润胀及溶解原位成像研究

Substantial progress toward the cost-effective processes involved in biomass to fuels is contingent upon fundamental breakthroughs in our current understanding of the complex cell wall ultrastructure in which the cellulose fibril aggregates (CFAs) are embedded in an amorphous matrix of cross-linked hemicelluloses and lignin, collectively known as “natural biomass recalcitrance”. In the present work, atomic force microscopy and in situ confocal Raman microscopy will be used to investigate size, distance, the period of helica twist of CFAs as well as the topochemical correlation between CFAs and matrix polymers in bamboo (Phyllostachys pubescens) cell wall at native state. The swelling mechanism of CFAs and accompanie 3D dynamic dissolution of cell wall components under various swelling systems (NaOH/Urea, Sodium hydroxide, Ionic liquids, N-methylmorpholine-N-oxide (NMMO)) will be explored. Meanwhile, it will elucidate the effect of lignin on CFAs swelling. Furthermore, the enzymatic hydrolysis mechanism of swelled CFAs will be exploited at micro and nano-scale. The findings will provide the theoretical basis and experimental evidence for the design of effectively converting process of bamboo biomass.

生物质原料高效转化为液体燃料很大程度上取决于对其细胞壁天然抗降解屏障（木质素包覆纤丝聚集体交联结构）的理解。本项目拟采用原子力显微镜以及原位共聚焦显微拉曼光谱仪，揭示天然状态下毛竹节间组织不同类型细胞纤丝聚集体的尺寸、间隙、旋转扭曲周期长度及纤丝聚集体与基质聚合物空间分布相关性。探索低温氢氧化钠/尿素、室温氢氧化钠、室温离子液体以及高温N-甲基吗啉-N-氧化物润胀体系下不同类型细胞纤丝聚集体润胀机制及所伴随的细胞壁组分三维动态溶解机制，阐明木质素包覆对纤丝聚集体润胀方式的影响。进一步在微纳尺度上解译不同润胀体系下纤丝聚集体的酶水解机制，其研究结果可为设计竹生物质原料高效转化路径提供理论指导和科学依据。

竹材作为重要的生物质原料高效转化为液体燃料很大程度上取决于对其细胞壁天然抗降解屏障（木质素包 覆纤丝聚集体交联结构）的理解。针对以上问题，本研究在组织、细胞以及亚细胞水平揭示了竹材的复杂性，同时探索了化学预处理对竹材细胞理化性能的影响机制。多尺度显微成像研究发现竹材在组织及细胞水平都存在明显的组分分布、含量及纤丝聚集体取向不均一性。在此研究基础上，硫酸预处理发现了毛竹纤维及薄壁细胞壁主要组分移除的区域选择性，成功制得纤维素纳米晶材料。对比研究了木质素包覆对纤丝聚集体润胀方式的影响，进一步在微纳尺度上解译不同润胀体系下纤丝聚集体的酶水解机制。以上研究结果为设计竹生物质原料高效转化路径提供了理论指导，扩大了天然纤维素基功能材料开发的原料选择范围。