毛竹纤维微纤丝取向的原子力显微镜观察

Visualization of cellulose microfibrils of Moso bamboo fibers with atomic force microscopy

为了观察到竹纤维不同壁层微纤丝的取向,该文利用原子力显微镜对毛竹纤维的微纤丝取向进行了高分辨观察。采用了两种样品制备方式,一是化学离析后纤维,用于观察竹纤维表层的微纤丝取向;二是经过脱木素处理后的弦切片(厚度为30μm),用于观察竹纤维细胞腔内壁的微纤丝取向。结果表明,毛竹纤维初生壁微纤丝呈无序排列,但其细胞腔内壁的微纤丝相对纤维长轴则几乎垂直排列,这种排列模式与木材细胞对应壁层微纤丝的排列模式相似。同时,还观察到某些壁层的微纤丝呈高度定向排列,但拍摄到这类图像的几率较小。该研究证实,利用原子力显微镜可以实现对竹纤维微纤丝取向的高分辩观察,并且样品制备远较透射电镜简单,可操作性强。

Atomic force microscope was used to investigate the arrangement of cellulose microfibrils （CMF） in Moso bamboo （Phyllostachys pubescens ） fibers. Two methods of sample preparation were used here for different purposes. The first method was chemical maceration with a mixture of hydrogen peroxide and glacial acetic acid, the fibers obtained through which were suitable for observing the orientation of CMF in the primary wall. The other method was to prepare tangential mierotomed sections with an approximate thickness of 30 μm. This method was used to investigate the arrangement of CMF in the inner wall of cell cavity of bamboo fibers. The results indicate that the CMF are randomly oriented in the primary wall while nearly vertical to the long axis of fibers in the inner wall of cell cavity,which is similar to the arrangement of CMF in the corresponding layer of wood fibers. Meanwhile, the highly oriented arrangement of CMF is also observed in a certain layer of bamboo fibers, though it is incapable of determining which layer it is in this study. The pilot investigation demonstrates that AFM is a powerful tool for the high-resolution observation of CMF in bamboo fibers, meanwhile, it has the advantages of simple procedure of sample preparation and easy operation compared to the traditional transmission electron microscopy.