竹纤维细胞壁多层构造的理化表征

Bamboo resource is one of the most promising alternatives to wood in the world. The characteristic properties of bamboo are determined to a large degree by the multi-lamellate structure, also a big challenge to be figured out, of thick-walled bamboo fibers. The objective of this project is to study the multi-lamellate structure of thick-walled bamboo fibers so as to explore the natural laws about how the cell wall forms, including the following methods: investigate the layers and the thicknesses of cell wall at nano level by using high resolution electron microscope system, such as atomic force microscope (AFM) and transmission electron microscope (TEM), and nano CT imaging system; determine the orientation of microfibrils in each layer and how the microfibril angle (MFA) changes in the cell wall with AFM and laser confocal Raman microscopy; analyze the chemical composition of the cell wall by combining advanced electron microscope system (TEM, confocal laser scanning microscope) with immunofluorescence staining and spectral imaging technology (ultraviolet microscopic spectroscopy); and build a three-dimensional multi-lamellate structure model of thick-walled bamboo fibers using the three-dimensional computer simulation technology. Quantitatively characterizing the nano structure of each layer in cell wall, orientation of microfibrils and distribution of chemical compositions is conducive to further studying the features of multi-lamellate structure of thick-walled bamboo fibers. The outputs will benefit many research fields including bamboo utilization, design and manufacture of biomimetic materials, biomass conversion, nano-cellulose preparation and so on.

竹类资源是最具有发展前景的林木资源之一，竹材细胞壁的多层构造是竹材优良特性的决定因素，也是难以攻克的基础问题。本项目以深入研究竹材细胞壁多层构造为目的，探索胞壁组成内在规律。采用高分辨电子显微镜系统（原子力显微镜、透射电镜）和纳米CT数据成像系统，在纳米尺度上揭示细胞壁的层数和层厚变化；采用原子力显微镜和激光共聚焦拉曼显微技术，确定细胞壁各层微纤丝的取向和微纤丝角的变化规律；利用免疫荧光细胞化学染色联合高分辨电子显微镜系统（透射电镜、激光共聚焦显微镜）和光谱成像技术（紫外显微分光光谱），分析细胞壁化学成分的微区分布；利用计算机三维模拟技术，构建细胞壁多层空间生物结构模型。力求定量表征细胞壁各层的纳米结构、微纤丝取向和化学成分微区分布，进一步认识竹材多壁层的结构特征。研究成果将为竹材的高质利用、材料设计、生物仿生、生物能源转化及纳米纤维素制备等提供科学依据。

竹类资源是最具有发展前景的林木资源之一，竹材细胞壁的多层构造是竹材优良特性的决定因素，也是难以攻克的基础问题。本项目以毛竹纤维为研究对象，从纤维细胞壁的壁层构造、微纤丝排列、化学组分分布等入手，利用现代研究手段和先进方法，深入研究了纤维细胞壁超微构造和物质组成，探索了胞壁组成的内在规律。采用高分辨率透射电镜、偏光成像系统、原子力显微镜等手段揭示了纤维细胞壁宽窄交替的多壁层构造，并解析了细胞壁微纤丝超微结构；采用高分辨率扫描电镜、激光共聚焦拉曼显微成像技术以及液晶偏光显微技术解析了细胞壁不同壁层微纤丝的取向，实现了细胞壁各壁层微纤丝角（MFA）的定量测算；采用激光共聚焦拉曼显微成像技术获得了纤维细胞壁中纤维素、木质素（G、S、H单元）和羟基肉桂酸的微区分布规律，采用高分辨率纳米红外光谱技术得到了纤维细胞壁各层中木聚糖的分布，并发现木质素与木聚糖的分布具有协同性。基于纤维细胞壁精细构造以及微纤丝取向的研究结果，并结合前人的研究成果，提出了成熟毛竹纤维细胞多壁层微纤丝取向模型。该研究促进了对竹子纤维细胞壁精细结构的认识，研究成果将为竹材的高质利用、材料设计、生物仿生、生物能源转化及纳米纤维素制备等提供科学依据。相关研究结果发表于《Annals of Botany》、《Industrial Crops and Products》、《Cellulose》、《Wood & Fiber Science》、《林业科学》等重要学术刊物，并多次在国内外学术会议上进行交流；项目目前共计发表学术论文28篇，其中SCI收录18篇，EI收录2篇；培养博士研究生3名。