Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
Biomacromolecules. 2012 Sep 10;13(9):2624-33. doi: 10.1021/bm300848c. Epub 2012 Aug 3.
Amphiphilic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) copolymers, also known as poloxamers, have broad biomembrane activities. To illustrate the nature of these activities, (1)H Overhauser dynamic nuclear polarization NMR spectroscopy was employed to sensitively detect polymer-lipid membrane interactions through the modulation of local hydration dynamics in lipid membranes. Our study shows P188, the most hydrophilic poloxamer that is a known membrane sealant, weakly adsorbs on the membrane surface, yet effectively retards membrane hydration dynamics. Contrarily, P181, the most hydrophobic poloxamer that is a known membrane permeabilizer, initially embeds at lipid headgroups and enhances intrabilayer water diffusivity. Unprecedented resolution for differentiating weak surface adsorption versus translocation of polymers to membranes is obtained by probing local water diffusivity in lipid bilayer systems. Our results illustrate that the relative hydrophilic/hydrophobic ratio of the polymer dictates its functions. These findings gleaned from local hydration dynamics are well supported by a thermodynamics study presented in the accompanying paper (Wang, J.-Y.; Marks, J. M.; Lee, K. Y. C. Biomacromolecules, 2012, DOI: 10.1021/bm300847x).
两亲性聚（环氧乙烷）-聚（环氧丙烷）-聚（环氧乙烷）共聚物，也称为泊洛沙姆，具有广泛的生物膜活性。为了说明这些活性的本质，（1）H 过相关动核极化 NMR 光谱被用来通过调制脂质膜中的局部水动力学来灵敏地检测聚合物-脂质膜相互作用。我们的研究表明，P188，最亲水的泊洛沙姆，是一种已知的膜密封剂，在膜表面上弱吸附，但有效地延缓了膜水合动力学。相反，P181，最疏水的泊洛沙姆，是一种已知的膜通透剂，最初嵌入脂质头部基团并增强层间水扩散率。通过探测脂质双层系统中的局部水扩散率，获得了区分聚合物对膜的弱表面吸附与易位的前所未有的分辨率。我们的结果表明，聚合物的相对亲水/疏水比决定了其功能。这些从局部水合动力学中得出的发现得到了伴随论文（Wang，J.-Y.；Marks，J. M.；Lee，K. Y. C.）中热力学研究的很好支持。生物大分子，2012 年，DOI：10.1021/bm300847x）。
