An ultrasensitive tool exploiting hydration dynamics to decipher weak lipid membrane–polymer interactions

• Published in: Journal of magnetic resonance (1997) 2012-02, Vol.215, p.115-119
• Main Authors: Cheng, Chi-Yuan, Wang, Jia-Yu, Kausik, Ravinath, Lee, Ka Yee C., Han, Songi
• Format: Article
• Language: English
• Subjects: Algorithms; Dynamic nuclear polarization; Electromagnetic Fields; Electron Spin Resonance Spectroscopy; Electrons; Fluorescent Dyes; Hydration dynamics; Hyperpolarization; Lipid Bilayers - chemistry; Membranes, Artificial; Overhauser effect; Phospholipids - chemistry; Poloxamer; Polyethylene Glycols - chemistry; Polymers; Polymer–lipid interaction; Polypropylenes - chemistry; Protons; Scattering, Radiation; Water - chemistry; X-Rays
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2011.12.004

[Display omitted] ► Modulation of interfacial hydration dynamics can report on molecular interactions. ► Unraveling weak molecular interactions by Overhauser DNP with site-specificity. ► No changes in structures/dynamics of participating molecules upon their interactions. We introduce a newly developed tool, 1H Overhauser Dynamic Nuclear Polarization (ODNP), to sensitively explore weak macromolecular interactions by site-specifically probing the modulation of the translational dynamics of hydration water at the interaction interface, in the full presence of bulk water. Here, ODNP is employed on an illustrative example of a membrane-active triblock copolymer, poloxamer 188 (P188), which is known to restore the integrity of structurally compromised cell membranes. We observe a distinct change in the translational dynamics of the hydration layer interacting with the lipid membrane surface and the bilayer-interior as P188 is added to a solution of lipid vesicles, but no measurable changes in the dynamics or structure of the lipid membranes. This study shows that hydration water is an integral constituent of a lipid membrane system, and demonstrates for the first time that the modulation of its translational diffusivity can sensitively report on weak polymer–membrane interactions, as well as mediate essential lipid membrane functions. ODNP holds much promise as a unique tool to unravel molecular interactions at interfaces even in the presence of bulk water under ambient conditions.