Aggregates of alginates binding with surfactants of single and twin alkyl chains in aqueous solutions: Fluorescence and dynamic light scattering studies
Aggregates of alginates binding with surfactants of single and twin alkyl chains in aqueous solutions: Fluorescence and dynamic light scattering studies
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水溶液中海藻酸盐与单链和双烷基链表面活性剂结合的聚集体：荧光和动态光散射研究
DOI：
10.1016/j.carbpol.2006.03.012
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发表时间：
2006-10-27
影响因子：
11.2
通讯作者：
Tong, Zhen
中科院分区：
文献类型：
--
作者：
Ren, Biye;Gao, Yiming;Tong, Zhen
天然聚电解质，特别是多糖类，是一类具有多种两亲性的化合物，广泛应用于食品、化妆品和医药等领域。海藻酸盐链含有MM、GG和MG三种二联体序列嵌段，这些残基序列赋予海藻酸盐链不同的刚度。因此，有趣的是，说明化学组成和顺序的海藻酸盐与带正电荷的表面活性剂的聚集的效果。单尾阳离子表面活性剂十二烷基三甲基溴化铵（DTAB）和双尾（Gemini）表面活性剂乙烷二基-1，2-双（十二烷基二甲基溴化铵）（1,2 -2- 1,2）被允许以不同的M/G比（分别为0.6和1.85）结合在海藻酸钠的天然聚阴离子上。利用芘探针的荧光发射和动态光散射研究了相互作用和聚集，以揭示表面活性剂组成和表面活性剂结构的影响。结果表明，Gemini表面活性剂12-2-12与相同尾长的单尾DTAB相比，协同聚集作用更强，而海藻酸钠与相同尾长的Gemini表面活性剂12-2-12和DTAB的结合强度几乎相同。此外，cac几乎不依赖于藻酸盐组合物和M和G序列。动态光散射表明，表面活性剂结合的海藻酸盐链的流体动力学半径Rh总是小于没有绑定。特别地，Rh随表面活性剂浓度表现出两种非常不同的变化趋势。结合12-2-12产生了深最低Rh在相当低的表面活性剂浓度比其CAC，而R-h单调下降，随着DTAB浓度的增加。最小Rh的出现可归因于由于与12-2-12结合而形成的藻酸盐链的发夹状构象。(c)2006爱思唯尔有限公司保留所有权利。
The natural polyelectrolytes, especially polysaccharides, are intensively used in foods, cosmetics, and pharmaceuticals with many amphiphiles. Alginate chain contains three types of dyad sequential blocks as MM, GG, and MG, and these residue sequences endow the alginate chains with different stiffness. It is therefore interesting to illustrate the effect of chemical composition and sequence of alginate on the aggregation with positively charged surfactants. The single-tail cationic surfactant dodecyltrimethyl ammonium bromide (DTAB) and twin-tail (Gemini) surfactant ethanediyl-1,2-bis (dodecyldimethylammoniuin bromide) (12-2-12) were allowed to bind on the natural polyanion of sodium alginate with different M/G ratios (0.6 and 1.85, respectively). The interaction and aggregation were investigated using fluorescence emission of pyrene probes and dynamic light scattering to reveal effects of the polyelectrolyte composition and surfactant structure. The results indicated that the cooperative aggregation was much stronger for the Gemini surfactant 12-2-12 than that for the single-tail DTAB with the same tail length and the binding strength of alginate to the both 12-2-12 and DTAB with the same tail length was almost identical. Also, the cac was almost independent of the alginate composition and M and G sequence. Dynamic light scattering illustrated that the hydrodynamic radius Rh for a surfactant-bound alginate chain was always smaller than that without binding. Particularly, the Rh exhibits two very different change trends with the surfactant concentration. Binding with 12-2-12 produced a deep minimum Rh at quite a lower surfactant concentration than its cac, while R-h monotonically decreased with increasing DTAB concentration. The appearance of the minimum Rh could be attributed to the hairpin-like conformation of the alginate chain formed due to binding with 12-2-12. (c) 2006 Elsevier Ltd. All rights reserved.