Exchange and Microviscosity of Dynamic Nanocompartments

TL;DR

This paper uses ESR to investigate the dynamics of water within reverse micelles, revealing how confinement and thermodynamic transitions influence water behavior at different temperatures, with implications for nanomaterials and biological systems.

Contribution

It introduces a novel ESR-based approach to separately probe interfacial and core water dynamics in reverse micelles, advancing understanding of confined water behavior under various conditions.

Findings

Thermodynamic transitions significantly affect water stability in RMs.

Different spin probes reveal distinct dynamics at interfaces and cores.

Insights into nucleation and ice growth in confined water environments.

Abstract

RMs (reverse micelles) provide a controlled system for studying the unique structural and dynamic behaviors of confined water, thus gaining a general insight into the behavior or water under confinement and at interfaces. This study employs ESR (Electron Spin Resonance) to study the dynamics inside RMs and capitalizes on the fact that different preparations of RMs can precisely manipulate both the size of water pools as well as whether or not different pools can come into contact. A small spin label moiety, less than a half nanometer in size tumbles in solution, offering insight into the rotational diffusion from room temperature down to deeply super-cooled temperatures. Two different spin probes can separately probe the dynamics of the interfacial layer vs. those at the core of the reverse micelle. The results provide critical insights into how thermodynamic transitions affect the stability and behavior of water in confined spaces, enhancing the understanding of nucleation and ice crystal growth, as well as the broader understanding of confined water's role in various chemical and biological systems. The ability to more precisely understand and control reaction dynamics and thermodynamics inside confined aqueous systems across a broad range of temperatures will prove useful to fields ranging from biophysics to the development of new nano-materials.