摘要
近红外线-傅里叶转化换光谱-拉曼光谱微分显微术可以用作成像,并不断确定对亚麻(Linum usitatissimum L)原茎组织中化学成份分布的位置。大约80μm的亚麻原茎截面,冷冻后再逐渐缓暖,并在相对湿度85%的条件下养生均衡3h;然后,将试样置于具有金色反射镜的显微镜载玻片上,并盖上盖玻片上。对所选用的组织截面,每次成像摄影利用约为185mW的集焦激光,所使用的拉曼光谱漂移范围是在16cm-1的3600-300cm-1,用256-512扫描,采用能控制显微镜自动运转的微机以收集50～150μm区域、垂直空间6～10μm步进式的图像立位,并将数码照相机拍摄的相片转化为可见的照片,每次成像数据的收集需要6～10h。化学视图是根据特定光谱区域内的面积积分而产生的。化学视图从组织细胞方式上,显示了亚麻化学成分中所有主要组成的位置。在CH脂肪质延伸区域的2850cm-1上有一个削尖的凸肩,它说明在角质层/薄壁组织上,明显地有蜡质存在。围绕在1600cm-1上的光带是由于芳族链延伸的振动形成的;证明在木芯组织上有木质素,以及在薄壁组织上有色素。围绕在1175-1050cm-1上的光带,是由于COC重原子的混合式的振动形成的;它说明在纤维细胞中聚集了最大量的碳水化合物,以及在木芯组织中很明显地只有较少的碳水化合物。此外,围绕在870-800,515-476以及400-360cm-1上的光带,表明了在薄壁柔软组织中有果胶、其他非纤维素性的聚糖和纤维素的存在。
Near-infrared-Fourier-transform-Raman（NIR-FT-Raman）microscopy was employed to image and subsequently produce in situ maps of the distribution of chemical components in flax（Linum usitatissimum L. ）stem tissue.Thick（-80 μm）cross-sections of flax were cryotomed,thawed,equilibrated at 85% RH for 3h and sealed under cover glasses on gold-mirrored microscope slides.Spectra for each image pixel were collected from selected tissue sections over the Raman shifted region 3600-300 cm^-1 at 16cm^-1 with 256-512 scans and employing 185 mW of focused laser power at the sample.A computer controlled automated-microscope stage was used to collect area maps of 50-150μm in rectangular dimensions in 6-10 n steps and register them to the visible images that were captured using a CCD camera.Data collection required 8-10 h per image. Chemical profiles were produced from area integrations of specffie spectral regions.The chemical profiles showed the location of all of the major components of flax by anatomical cell type.A sharp shoulder at 2850 cm^-1,in the CH stretch region provided evidence of waxes in the cuticular/epidermal tissue. The bands occurring around 1500 cm^-1,due to aromatic ring stretching vibrations,gave evidence of lignin in core tissue and pigments in epidermal tissue.Bands occurring between 1175-1050 cm^-1,due to COC heavy atom mixed mode vibrations,showed the greatest concentration of carbohydrate in fiber cells with lesser （hut significant）amounts indicated in core tissue.In addition,bands occurring between 870-800,515-476 and 400-360 cm^-1 gave specific evidence for the presence of pectins,other non-cellulosic polysaccharides and cellulose, respectively,in parenchyma tissue.Published by Elsevier Science B.V.
