Murray S B, Neville A C
School of Biological Sciences, University of Bristol, UK.
Int J Biol Macromol. 1997 Apr;20(2):123-30. doi: 10.1016/s0141-8130(96)01151-8.
The alpha-chitin used in the experiments came from crab shell waste. This was boiled in 3M HC1 to form a colloidal suspension of chitin crystallites. The electrostatic 'cost' surrounding the chitin was then manipulated in two ways. The first was the alteration of the pH of the chitin colloid (Chitin pKa = 6.1). This allowed the charge density on the crystalline rod of chitin to be altered. The second way was to alter the background charge in the environment by adding salt solutions to the colloid. The effect of the treatments was ascertained by measuring the diameter of the spherulites formed in vitro. These spherulites formed via self assembly through a liquid crystalline cholesteric phase. Raising the pH (within limits), resulted in larger spherulites. Raising the background charge also gave larger spherulites (within limits). As such both background charge and charge on the rod can be used to control the self assembly of the cholesteric spherulites. Manipulation of the electrostatic coat of the chitin could be a method of cellular remote control for formation of the helicoid in arthropod cuticle. This would allow the arthropods to set up conditions that aid the self assembly process.
实验中使用的α-甲壳素来自蟹壳废料。将其在3M盐酸中煮沸，形成甲壳素微晶的胶体悬浮液。然后通过两种方式控制甲壳素周围的静电“成本”。第一种是改变甲壳素胶体的pH值（甲壳素的pKa = 6.1）。这使得甲壳素结晶棒上的电荷密度得以改变。第二种方法是通过向胶体中添加盐溶液来改变环境中的背景电荷。通过测量体外形成的球晶直径来确定处理的效果。这些球晶通过液晶胆甾相自组装形成。提高pH值（在一定范围内）会导致形成更大的球晶。提高背景电荷也会产生更大的球晶（在一定范围内）。因此，背景电荷和棒上的电荷都可用于控制胆甾型球晶的自组装。操纵甲壳素的静电涂层可能是节肢动物表皮中螺旋体形成的一种细胞远程控制方法。这将使节肢动物能够设定有助于自组装过程的条件。
