Department of Chemistry, Beckman Institute and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
Bioresour Technol. 2010 Jul;101(14):5578-85. doi: 10.1016/j.biortech.2010.01.136. Epub 2010 Feb 19.
Efforts to further the potential of the large perennial grass Miscanthusxgiganteus as a biofuel feedstock would be aided by the ability to image the chemical species present during the fuel production process. Toward this end, two mass spectrometry imaging (MSI) approaches have been investigated here-laser desorption/ionization mass spectrometry (LDI-MS) and secondary ion mass spectrometry (SIMS). As a first step, cross sections of Miscanthus were subjected to a variety of sample preparation methods to optimize conditions for MSI. For LDI-MS, a thin metal coating (2 nm thick Au) provided high quality signals of saccharide-related ions. The traditional matrix-assisted laser desorption/ionization matrix, 2,5-dihydroxybenzoic acid, also showed high efficiency for the desorption of saccharide-related ions. In contrast, with alpha-cyano-4-hydroxycinnamic acid matrix, these ions were nearly absent in the mass spectra. Direct laser ablation of untreated Miscanthus sections was also performed. High resolution images, where the fine structure of the vascular bundle could be clearly visualized, were obtained using SIMS. Although coating the sections with a nanometer thick Au layer can greatly enhance the quality of SIMS images, the coating had limited effect on secondary ion signal enhancement. Using the optimized mass spectrometry approaches described here, information on the spatial distribution of several saccharides was obtained.
若能在燃料生产过程中对化学物质进行成像，将有助于进一步挖掘大刍草（Miscanthus x giganteus）作为生物燃料原料的潜力。为此，本研究调查了两种质谱成像（MSI）方法——激光解吸/电离质谱（LDI-MS）和二次离子质谱（SIMS）。作为第一步，对大刍草的横截面进行了各种样品制备方法处理，以优化 MSI 的条件。对于 LDI-MS，薄的金属涂层（2nm 厚的 Au）提供了高质量的糖相关离子信号。传统的基质辅助激光解吸/电离基质 2,5-二羟基苯甲酸，也显示出对糖相关离子解吸的高效率。相比之下，用 α-氰基-4-羟基肉桂酸基质时，这些离子在质谱中几乎不存在。还对未经处理的大刍草切片进行了直接激光烧蚀。使用 SIMS 获得了高分辨率图像，其中可以清楚地观察到维管束的精细结构。尽管用纳米厚的 Au 层涂覆切片可以大大提高 SIMS 图像的质量，但涂层对二次离子信号增强的影响有限。使用这里描述的优化质谱方法，获得了几种糖的空间分布信息。
