Visualization of higher structures of lignin by TOF-SIMS

木质素在植物细胞壁中的分布是不均匀的，无论是在浓度和结构上，即使在同一植物中，取决于细胞类型和细胞壁定位。因此，需要在形态和分子水平上对木质素进行进一步研究。显微镜研究已被用来观察细胞壁中完整木质素的化学结构。例如，SEM-或TEM-EDXA，与木质部细胞的溴化、具有木质素的特定结构的选择性放射性标记的显微放射自显影2 -5）和UV/VTS显微光谱学的组合已用于此目的。这些技术提供了高分辨率的形态学信息;然而，详细的化学信息是有限的。近年来，各种免疫标记的木质素的定位被报道，这为在超微结构水平上原位化学分析这些结构提供了一个新的方向。飞行时间二次离子质谱（TOF-SIMS）是一种方便的技术，可以提供固体样品表面的化学信息。利用质谱和二次离子图像可以确定样品表面组分的组成和分布。本研究将飞行时间二次离子质谱应用于木材细胞壁的非降解分析。利用飞行时间二次离子质谱（TOF-SIMS）研究了树木木质部木质素的结构。在飞行时间二次离子质谱分析，松树和山毛榉粉碎木材木质素（MWLs）产生了一些二次离子含有愈创木基或胡萝卜素核。用苯丙氨酸-d 7处理的木兰木质部产生的图像显示了氘标记物在木质部表面的定位.这些结果表明，飞行时间-二次离子质谱分析适用于无定形生物聚合物木质素，因此可用于方便地评估木材和纸浆的质量。该方法可进一步应用于木质素等生物聚合物的生物合成研究。

Lignin in plant cell walls is distributed heterogeneously, both in concentration and structure, even in the same plant, depending upon the cell type and cell wall localization. Further studies of lignin both at the morphological and molecular levels are therefore required. Microscopic studies have been utilized to observe the chemical structure of intact lignin in cell walls. For example, SEM- or TEM-EDXA, with the combination of bromination of xylem cells, microautoradiography with selective radiolabeling of specific structures of lignin2-5) and UV/VTS microspectroscopies have been used for this purpose. These techniques provide high-resolution morphological information ; however detailed chemical information is limited. Recently, the localization of various immunolabeled lignins was reported, showing a new direction for the chemical analysis of these structures at the ultrastructural level in situ.TOF-SIMS (time-of-flight secondary ion mass spectrometry) is a convenient technique providing chemical information on solid sample surfaces. The mass spectrum and secondary ion images can be used to determine the composition and distribution of the sample surface constituents.In this study, TOF-SIMS is applied to the non-degradative analysis of wood cell walls. The structure of tree xylem ligfiin was investigated by TOF-SIMS. On TOF-SIMS analysis, pine and beech milled wood lignins (MWLs) produced some secondary ions containing guaiacyl or syringyl nuclei. Magnolia xylem, fed with phenylalanine-d7, produced an image showing the localization of thedeuterium-label on the xylem surface.These results indicate that TOF-SIMS analysis is applicable to the amorphous biopolymer lignin, and is therefore useful for convenient estimations of wood and pulp quality. This method can be further applied to the study of the biosynthesis of biopolymers such as lignin.