Kaneko Tatsuo, Okajima Maiko K
Energy and Environmental Area, Graduate School of Advanced Science and Technology, Japan Advanced Institute of Science and Technology.
Yakugaku Zasshi. 2018;138(4):489-496. doi: 10.1248/yakushi.17-00201-1.
Cyanobacteria fix carbon dioxide and nitrogen from the atmosphere using solar energy to produce various biomolecules, and thus are regarded as ultimately ecological microreactors. Sacran is a cyanobacterial polysaccharide with a very high molecular weight of 29 Mg/mol, which is extracted from Aphanothece sacrum cyanobacterium mass-cultivated in freshwater environments such as river or spring. Sacran is a water-soluble heteropolysaccharide comprising more than 6 kinds of sugar residues and contains 12% sulfate anionic groups and 27% carboxyls. Sacran has a super-absorbent function of water, which can retain 6000 mL for 1 g specimen, due to very long hydrating chains. The value is much higher than hyaluronic acid or conventional super-absorbent polymers. Sacran exhibits self-orienting behavior in dilute solution at a concentration range over 0.25 wt%, which is quite low when compared with conventional liquid crystalline polysaccharides. Mesogenic helical chains of sacrans have extremely high aspect ratios of 1600 for highly persistent lengths of 32 micrometer. Through the liquid crystallinity, sacran solution shows a shear-thinning behavior and the solution spread over a substrate such as biological skin very efficiently to create a thin layer. Applied on atopic dermatitis skin sacran solution exerts excellent moisturizing effect and anti-itching action.
蓝细菌利用太阳能固定大气中的二氧化碳和氮，以产生各种生物分子，因此被视为最终的生态微反应器。Sacran是一种分子量非常高，达29兆克/摩尔的蓝细菌多糖，它是从在河流或泉水等淡水环境中大规模培养的聚球藻中提取的。Sacran是一种水溶性杂多糖，包含6种以上的糖残基，含有12%的硫酸阴离子基团和27%的羧基。由于水合链非常长，Sacran具有超强的吸水功能，1克样品可保留6000毫升水。该值远高于透明质酸或传统的高吸水性聚合物。Sacran在浓度超过0.25 wt%的稀溶液中表现出自取向行为，与传统的液晶多糖相比，这一浓度相当低。Sacran的介晶螺旋链具有极高的长径比，达到1600，持久长度为32微米。通过液晶性，Sacran溶液表现出剪切变稀行为，并且溶液能非常有效地铺展在诸如生物皮肤等基质上以形成薄层。将Sacran溶液应用于特应性皮炎皮肤，具有出色的保湿效果和止痒作用。
