He Chuan, Zhou Xia, Yao Chun-li, Xu Feng
Guang Pu Xue Yu Guang Pu Fen Xi. 2015 Sep;35(9):2553-7.
Confocal Raman microspectroscopy (CRM) represents a powerful technique that can provide insights into topochemistry in lignocellulosic biomass cell wall. In this work, CRM was used to explore the impact of dilute acid (DA) pretreatment on the topochemistry of lignin and hydroxycinnamic acid (HCA) in the-fiber cell walls of Miscanthus × giganteus internode. Raman spectra extracted from different morphological regions of untreated fiber cell walls indicated the heterogeneous concentration of lignin and HCA. There is a companied trend between them, that is, regions where there is the higher lignin concentration have the higher concentration of HCA. When treated with DA, it was found that the intensity of 1600 cm(-1) (lignin) and 1170 cm(-1) (HCA) were decreased, which could be contributed to the partially removal of lignin and HCA. The removal rate in different morphological areas followed the decreasing order: secondary cell wall (SW) > compound middle lamella (CML) > cell corner middle lamella (CCML). The increase of the Raman band intensity ratio (1170/1600) indicated the preferential removal of lignin in the SW and CML as a result of DA pretreatment, while the constant of the ratio meant there is no preference between lignin and HCA in the CCML. The research will provide the deep understanding of the topochemistry of lignin and HCA at sub-cellular level during DA pretreatment, meanwhile, it also expands the application of Raman spectra in the research area of plant cell wall.
共聚焦拉曼显微光谱（CRM）是一种强大的技术，可用于深入了解木质纤维素生物质细胞壁的表面化学。在本研究中，利用CRM探究了稀酸（DA）预处理对芒草茎节纤维细胞壁中木质素和羟基肉桂酸（HCA）表面化学的影响。从未处理的纤维细胞壁不同形态区域提取的拉曼光谱表明木质素和HCA的浓度存在异质性。它们之间存在一种伴随趋势，即木质素浓度较高的区域HCA浓度也较高。用DA处理后，发现1600 cm⁻¹（木质素）和1170 cm⁻¹（HCA）处的强度降低，这可能是由于木质素和HCA被部分去除。不同形态区域的去除率顺序为：次生细胞壁（SW）＞复合中层（CML）＞细胞角隅中层（CCML）。拉曼带强度比（1170/1600）的增加表明DA预处理导致SW和CML中木质素被优先去除，而该比值不变意味着CCML中木质素和HCA之间没有优先去除情况。该研究将有助于在亚细胞水平深入了解DA预处理过程中木质素和HCA的表面化学，同时也拓展了拉曼光谱在植物细胞壁研究领域的应用。
