Department of Chemical and Biomolecular Engineering and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
Bioresour Technol. 2010 Jul;101(13):4919-25. doi: 10.1016/j.biortech.2009.10.096. Epub 2009 Dec 21.
Confocal raman microscopy has been used to monitor the structural and chemical changes upon NaOH treatment of Miscanthus x giganteus, a potential energy crop and a model lignocellulosic material. Longitudinal and transversal-section images of the parenchyma cells in raw miscanthus samples reveal that lignin and cellulose are collocated in the cell wall and that a globular structure, composed predominantly of hemicellulose and lignin is associated with the interior cell wall. NaOH treatment results in the complete removal of lignin at long processing time but leaves the cellulose largely undisturbed as evidenced by the lack of conversion from type I to type II cellulose. Depth profiling images of partially processed (short exposure time) parenchyma cells reveal that lignin is removed preferentially from the interior surface of the cell wall as indicated by the anisotropic distribution of lignin and cellulose across the cell wall in partially processed samples. These spatially resolved chemical changes are important, because they illustrate how even simple pre-processing protocols can develop complex molecular profiles by differential rates of attack on the major components of the cell wall.
共聚焦拉曼显微镜被用于监测碱处理芒草（一种有潜力的能源作物和木质纤维素模型材料）过程中的结构和化学变化。对原芒草样品的薄壁细胞进行的纵向和横向切片图像显示，木质素和纤维素共同存在于细胞壁中，而一个主要由半纤维素和木质素组成的球状结构与细胞壁内部相关联。NaOH 处理在较长的处理时间内导致木质素完全去除，但纤维素基本不受影响，这可从纤维素 I 型向纤维素 II 型的转化缺失得到证明。对部分处理（短暴露时间）的薄壁细胞的深度分布图像显示，木质素优先从细胞壁的内表面去除，这可从部分处理样品中横跨细胞壁的木质素和纤维素的各向异性分布看出。这些空间分辨的化学变化很重要，因为它们说明了即使是简单的预处理方案也可以通过细胞壁主要成分的不同攻击速率来发展出复杂的分子谱。
