A spectroscopic study of the self-association and inter-molecular aggregation behaviour of pH-responsive poly(L-lysine iso-phthalamide)
A spectroscopic study of the self-association and inter-molecular aggregation behaviour of pH-responsive poly(L-lysine iso-phthalamide)
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DOI：
10.1016/j.polymer.2006.02.059
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发表时间：
2006-04-05
期刊：
影响因子：
4.6
通讯作者：
Kaminski, CF
中科院分区：
文献类型：
--
作者：
Dai, XW;Eccleston, ME;Kaminski, CF
在pH值和浓度范围内的水溶液中，研究了一系列两亲性聚（l -赖氨酸异邻苯二胺）聚合物的pH介导的分子内结合和分子间聚集。这些新型生物反应性两亲性聚合物的预期功能是通过l -赖氨酸部分沿聚合物主链结合垂坠的亲水羧基来实现的，通过异邻苯二甲酸部分引入一定程度的疏水性来平衡。在响应性聚合物骨架中加入低水平的双功能Cy3（聚Cy3）和/或Cy5染料（聚Cy3/5或聚Cy5）共单体，可以使用光学光谱技术的组合来详细探测pH介导的疏水关联。稳态荧光光谱和荧光寿命测量显示，聚cy3在pH值为4.5时发生了构象转变。因此，在低于临界pH值时，聚合物坍塌成紧凑的球状结构（超螺旋），使荧光团分子彼此靠近。这导致在单荧光团系统（聚cy3）的荧光强度和荧光寿命显著降低，并伴有最大发射波长的红移。观察到发射最大值的红移和荧光寿命随着聚合物浓度的增加而增强，表明聚合物聚集体的形成。在含有聚cy3（供体）和聚Cy5（受体）的单荧光团和含有聚cy3（供体）/Cy5（受体）的双荧光团的混合物中测量荧光共振能量转移（FRET），以区分分子内与分子间的结合。结果的相关性，相对于潜在的体内应用（药物输送和生物诊断）进行了讨论。(c) 2006 Elsevier Ltd.版权所有。
The pH mediated intra-molecular association and inter-molecular aggregation of a rang of amphiphilic poly(L-lysine iso-phthalamide) polymers have been investigated in aqueous solution over a range of pH values and concentrations. The desired functionality of these novel bioresponsive amphiphilic polymers was achieved by incorporating pendant hydrophilic carboxyl groups along the polymer backbone, via the L-lysine moiety, balanced by a degree of hydrophobicity introduced via the iso-phthaloyl moiety. Incorporation of low levels of bis-functional Cy3 (poly-Cy3) and/or Cy5 dye (poly-Cy3/5 or poly-Cy5) co-monomers in the responsive polymer backbone allowed detailed probing of the pH mediated hydrophobic association using a combination of optical spectroscopic techniques. Both steady-state fluorescence spectroscopy and fluorescence lifetime measurements of poly-Cy3 revealed a conformational transition at pH 4.5. Thus, below a critical pH the polymer collapsed into a compact globular structure (hypercoil) bringing the fluorophore molecules into close proximity with one another. This resulted in a dramatic reduction in fluorescence intensity and fluorescent lifetime in the single fluorophore systems (poly-Cy3) accompanied by a red shift in the maximum emission wavelength. Observed redshifts in the emission maxima and enhancements of fluorescent lifetimes with increasing polymer concentration suggested the formation of polymer aggregates. Fluorescence resonance energy transfer (FRET) was measured in mixtures of single fluorophore containing poly-Cy3 (donor) and poly-Cy5 (acceptor) and dual fluorophore containing poly-Cy3 (donor)/Cy5 (acceptor) in an effort to distinguish between intra-molecular versus inter-molecular association. The relevance of the results with respect to potential in vivo applications (drug delivery and biodiagnostics) is discussed. (c) 2006 Elsevier Ltd. All rights reserved.