A salt-free zero-charged aqueous onion-phase enhances the solubility of fullerene C60 in water.
A salt-free zero-charged aqueous onion-phase enhances the solubility of fullerene C60 in water.
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DOI：
10.1021/jp054637m
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发表时间：
2006-01
期刊：
影响因子：
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通讯作者：
Hongguang Li;Xiang-feng Jia;Yi Li;Xingwang Shi;J. Hao
中科院分区：
文献类型：
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作者：
Hongguang Li;Xiang-feng Jia;Yi Li;Xingwang Shi;J. Hao
由无盐的零电荷阳离子和阴离子（阴阳离子）表面活性剂十四烷基三甲基氢氧化铵（TTAOH）/月桂酸（LA）/H2O的混合物制备洋葱相（多层囊泡相或L α相）。H+和OH-抗衡离子形成水（TTAOH + LA -> TTAL + H2O），使溶液不含盐。洋葱相溶液具有新的性质，包括低电导率，低渗透压和阳离子和阴离子表面活性剂之间的静电排斥，因为没有盐。通过冷冻断裂透射电子显微镜（FF-TEM）测量，球形多层囊泡的平均半径为250 nm，最大层间距离为，即，疏水双层和水层的厚度通过小角X射线散射（SAXS）计算为约52 nm。在这种无盐零电荷的水洋葱相中，可以溶解非常疏水的C60富勒烯。作为典型的结果，0.588 mg.mL（-1）（约0.82 mmol.L（-1））C60已成功地溶解到50 mmol.L（-1）阴阳离子表面活性剂的阳离子相水溶液中。富勒烯与TTAL的重量比计算为约1：40。通过使用不同的样品制备路线，研究了C60在无盐阴阳离子洋葱相溶液中的增溶作用，并使用各种技术来表征这些囊泡系统，有或没有封装的C60。在C60溶解后，洋葱相溶液的颜色从略带蓝色变为黄色或棕色。1H和13 C NMR测量表明C60分子位于疏水层中，即，在TTAL洋葱相的疏水层的中心位置[ω-CH 3和δ-（CH 2）x]。无盐的零电荷的阴阳离子囊泡水溶液是提高C60在水溶液中的溶解度的良好候选者，并且可以拓宽富勒烯的功能以在生物学、医学和材料中具有新的潜在应用。希望我们的方法也可以扩展到在水溶液中溶解功能化的碳纳米管。
An onion-phase (multilamellar vesicular phase or Lalpha-phase) was prepared from salt-free zero-charged cationic and anionic (catanionic) surfactant mixtures of tetradecyltrimethylammonium hydroxide (TTAOH)/lauric acid (LA)/H2O. The H+ and OH- counterions form water (TTAOH + LA --> TTAL + H2O), leaving the solution salt free. The onion-phase solution has novel properties including low conductivity, low osmotic pressure and unscreened electrostatic repulsions between cationic and anionic surfactants because of the absence of salt. The spherical multilamellar vesicles have an average 250 nm radius as measured by freeze-fracture transmission electron microscopy (FF-TEM) and the maximum interlayer distance, i.e., the thickness of the hydrophobic bilayer and the water layer, was calculated to be around 52 nm by small-angle X-ray scattering (SAXS). Extremely hydrophobic C60 fullerene can be solubilized in this salt-free zero-charged aqueous onion-phase. As a typical result, 0.588 mg.mL(-1) (approximately 0.82 mmol.L(-1)) C60 has been successfully solubilized into a 50 mmol.L(-1) catanionic surfactant onion-phase aqueous solution. The weight ratio of fullerene to TTAL is calculated to be around 1:40. Solubilization of C60 in the salt-free catanionic onion-phase solution was investigated by using different sample preparation routes, and a variety of techniques were used to characterize these vesicular systems with or without encapsulated C60. The onion-phase solution changed color from slightly bluish to yellow or brown after C60 was solubilized. 1H and 13C NMR measurements indicated that the C60 molecules are located in the hydrophobic layers, i.e., in the central positions [omega-CH3 and delta-(CH2)x] of the hydrophobic layers of the TTAL onion-phase. Salt-free zero-charged catanionic vesicular aqueous solutions are good candidates for enhancing the solubility of C60 in aqueous solutions and may broaden the functionality of fullerenes to new potential applications in biology, medicine, and materials. Hopefully, our method can also be extended to solubilize functionalized carbon nanotubes in aqueous solutions.