Cellulose chirality

纤维素手性

• 批准号: RGPIN-2014-04448
• 负责人: Gray, Derek
• 金额: $ 2.19万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=587815
• 关键词: Cellulose; chirality

There has been a renaissance in cellulose research, based on its ubiquitous structural role in the plant cell wall, its value as an abundant, renewable, carbon-neutral and non-toxic material that contributes to the strength of wood, paper, textiles and nanocomposites. We plan to focus on one neglected cellulose property, namely its chirality. The chirality is expressed over several length scales. Of course, the individual glucose units contain chiral carbon centres, but at longer length scales, this chirality also influences the crystalline structure of cellulose, and the superstructure of plant cell walls, pulp fibres, paper and wood. One aspect of the renaissance has been the world-wide interest in various forms of nanocellulose (a field where our research has garnered a lot of recognition this year). But there remain several untapped areas of research at larger length scales that we would like to address in this proposal. Over the years, we have observed, for the first time, the chiral structure and response of several cellulosic materials. We plan to focus on two particular observations. First, we found that ordered colloidal suspensions of cellulose nanocrystals form a left-handed chiral nematic structure, implying that there is some chiral interaction between the rod-like nanocrystals. We and others have speculated about the nature of this interaction, but experimental evidence is lacking. We hope to apply AFM force measurements to address this problem directly. Choice of cellulose samples and instrument geometries will be the key variables. Second, we’ve isolated for the first time a right-handed coiled cellulose-based structure from the petioles (leaf-stems) of many plants. Whether the handedness is a function of the chiral interactions of cellulose microfibrils, or is a result of biosynthetic pathways (or both) is unclear. In any case, the observed structures would seem to play a role in water transport through the plant vascular system. While the vascular system of plants has been extensively investigated, many questions on this key natural process remain. We would like to examine the significance of our preliminary observations on petiole structure and function from a physico-chemical viewpoint.

纤维素研究出现了复兴，这是基于其在植物细胞壁中普遍存在的结构作用，以及其作为丰富、可再生、碳中性和无毒材料的价值，有助于提高木材、纸张、纺织品和纳米复合材料的强度我们计划关注一个被忽视的纤维素特性，即它的手性。当然，单个葡萄糖单元包含手性碳中心，但长度更长。除了鳞片之外，这种手性还影响纤维素的晶体结构以及植物细胞壁、纸浆纤维、纸张和木材的上层结构，复兴的一个方面是全世界对各种形式的纳米纤维素的兴趣（我们研究的领域。今年获得了很多认可），但我们希望在本提案中讨论一些尚未开发的更大规模的研究领域。 多年来，我们首次观察到了几种纤维素材料的手性结构和响应，我们计划重点关注两个特定的观察结果，首先，我们发现纤维素纳米晶体的有序胶体悬浮液形成左手性向列。结构，这意味着棒状纳米晶体之间存在一些手性相互作用，我们和其他人推测了这种相互作用的性质，但缺乏实验证据，我们希望应用 AFM 力。直接解决这个问题的测量方法选择纤维素样品和仪器几何形状将是关键变量。 其次，我们首次从许多植物的叶柄（叶茎）中分离出右旋卷曲纤维素结构，该结构是否是纤维素微纤维手性相互作用的函数，或者是纤维素微纤维手性相互作用的结果。无论如何，观察到的结构似乎在植物维管系统的水运输中发挥作用，虽然植物的维管系统已得到特别研究，但关于这一关键的许多问题。我们想从物理化学的角度来检验我们对叶柄结构和功能的初步观察的意义。