Abstract: [Objective] Cellulose microfibril aggregate is the main component of bamboo cell wall which is important to study. However, bamboo cell wall is too hard to prepare the sample, and the technology with high resolution is not enough. Therefore, it is very different to study the cellulose micrifibril aggregates in bamboo cell wall.[Method] Bamboo strips were delignified by chemical treatment before being immersed in resin. Then the delignified bamboo cell wall was cut and polished by diamond knife which was ready for observing with an atomic force microscopy(AFM). The cellulose microfbril aggregates in bamboo fiber and parenchyma cell wall were investigated by Tapping Mode using an AFM.[Result] Height images and phase images were obtained by observing the prepared bamboo samples with an AFM.There were polylamellate structures in both fiber and parenchyma cell wall which changed according to the position in the vascular bundle. The amount of high bright material changed in different position of each layer was calculated by observing the phase images in one vascular bundle. Besides, the high bright material between the neighbor layers was more than other place; the size of high bright materials was similar in fiber cell wall, but different in parenchyma cell wall.[Conclusion] The Tapping Mode in AFM is an effective method to observe bamboo cell wall with pre-treatment which can not only get the image chosen before but also can get the information both on polylamellate structure and on cellulose microfibril aggregates in each cell wall layer. Cellulose microfibril aggregates distributed randomly in the cross section of both fiber and parenchyma cell wall. The amount of cellulose microfibril aggregates was various in different layers of bamboo fiber cell wall. Cellulose micrifibril aggregates in fiber cell wall were obviously higher in the edge of each layer than that in the middle place, which was more obvious in the parenchyma cell wall. The size of cellulose microfibril aggregate was almost the same in fiber cell wall, but different in parenchyma cell wall.

Key words: AFM, bamboo, cell wall, microfibril aggregate