Structure and solvation properties of aqueous sulfobetaine micelles in the presence of organic spin probes: a Molecular Dynamics simulation study

Structural and mechanical-dynamical information on a micelle formed by 72 monomers of N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB 3-12) in water solution have been obtained through Molecular Dynamics simulations. Additional simulations have been carried out to evaluate whether and to what extent the structural features of the micelle are affected by the presence of a spin probe, typically utilized for the experimental characterization of these, rather complex, systems. Results indicate that the micelle shows a spherical shape not heavily influenced by the presence of the probe which only produces a slight volume increase. Further analysis also indicates that the probe, although inducing scarce alterations at the micelle-solvent interface, heavily influences the micelle core which appears less stable (more fluctuating) and less hydrated. Finally, analysis of residence times of water indicate-in line with many previous studies-the presence of a dual population characterized by different interactions with micelle interior.