Selective fluorescence detection of divalent and trivalent metal ions with functionalized lipid membranes
作者:Jennifer L. Pincus、Chunyang Jin、Wenjian Huang、Hollie K. Jacobs、Aravamudan S. Gopalan、Yujiang Song、John A. Shelnutt、Darryl Y. Sasaki
DOI:10.1039/b501631b
日期:——
A series of functionalized lipid membranes were shown to respond selectively to Fe3+, Cr3+, Cu2+, and Fe2+ with a distinctive change in bilayer fluorescence. The optical response is due to a change in the aggregational state of functionalized, pyrene-labeled lipids as they recognize and bind to the metal ion. Two new lipids are introduced with 2,2′-bipyridine (PSBiPy) and N-methylamide (PSMA) headgroups. These functionalized lipids, along with two other lipids having hydroxyl (PSOH) and iminodiacetic acid (PSIDA) headgroups, were incorporated into bilayers of distearylphosphatidylcholine (DSPC) producing materials that exhibited an excellent range of sensitivity for the metal ions at low pH. At neutral pH the metal ion sensitivities were lost for PSOH and PSMA while the sensitivity and selectivity for Cu2+ increased for PSBiPy. In addition to optical sensing, the bilayers also can undergo restructuring of the membrane architecture. Dynamic light scattering and transmission electron microscope images show that for the majority of the bilayers, metal ion addition caused only aggregation of the vesicles. However, for the PSBiPy/DSPC membranes extraordinary square-shaped assemblies of planar bilayers formed in the presence of 100 µM Cu2+.
一系列功能化脂质膜对 Fe3+、Cr3+、Cu2+ 和 Fe2+ 有选择性响应,双层荧光发生明显变化。光学响应是由于功能化、芘标记的脂质识别并与金属离子结合时聚集状态的变化所致。引入了两种具有 2,2'-联吡啶 (PSBiPy) 和 N-甲基酰胺 (PSMA) 头基的新脂质。这些功能化脂质与其他两种具有羟基 (PSOH) 和亚氨基二乙酸 (PSIDA) 头基的脂质一起被掺入二硬脂酰磷脂酰胆碱 (DSPC) 双层中,生成的材料在低 pH 下对金属离子表现出优异的敏感性。在中性 pH 值下,PSOH 和 PSMA 的金属离子敏感性丧失,而 PSBiPy 对 Cu2+ 的敏感性和选择性增加。除了光学传感之外,双层膜还可以进行膜结构的重组。动态光散射和透射电子显微镜图像显示,对于大多数双层,金属离子的添加仅引起囊泡聚集。然而,对于 PSBiPy/DSPC 膜,在 100 µM Cu2+ 存在下形成了平面双层的非凡方形组件。