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DNA functions only in aqueous environments and adopts different conformations depending on the hydration level. The dynamics of hydration water and hydrated DNA leads to rotating and oscillating dipoles that, in turn, give rise to a strong megahertz to terahertz absorption. Investigating the impact of hydration on DNA dynamics and the spectral features of water molecules influenced by DNA, however, is extremely challenging because of the strong absorption of water in the megahertz to terahertz frequency range. In response, we have employed a high-precision megahertz to terahertz dielectric spectrometer, assisted by molecular dynamics simulations, to investigate the dynamics of water molecules within the hydration shells of DNA as well as the collective vibrational motions of hydrated DNA, which are vital to DNA conformation and functionality. Our results reveal that the dynamics of water molecules in a DNA solution is heterogeneous, exhibiting a hierarchy of four distinct relaxation times ranging from ~8 ps to 1 ns, and the hydration structure of a DNA chain can extend to as far as ~18 A from its surface. The low-frequency collective vibrational modes of hydrated DNA have been identified and found to be sensitive to environmental conditions including temperature and hydration level. The results reveal critical information on hydrated DNA dynamics and DNA-water interfaces, which impact the biochemical functions and reactivity of DNA. 

The self-assembly in aqueous solutions of three quaternary salt-based C 16 -type cationic surfactants with different polar head groups and identical carbon alkyl chain viz. , cetylpyridinium bromide (CPB), cetyltrimethylammonium tosylate (CTAT), and cetyltriphenylphosphonium bromide (CTPPB) in the presence of 1-butanol (BuOH) and 1,4-butanediol (BTD) was investigated using tensiometry, 2D-nuclear Overhauser enhancement spectroscopy (2D-NOESY) and small angle neutron scattering (SANS) techniques. The adsorption parameters and micellar characteristics evaluated at 303.15 K distinctly showed that BuOH promotes the mixed micelle formation while BTD interfered with the micellization phenomenon. The SANS data fitted using an ellipsoid (as derived by Hayter and Penfold using the Ornstein-Zernike equation and the mean spherical approximation) and wormlike micellar models offered an insight into the micelle size/shape and aggregation number ( N agg ) in the examined systems. The evaluated descriptors presented a clear indication of the morphology transition in cationic micelles as induced by the addition of the two alcohols. We also offer an investigation into the acceptable molecular interactions governing the differences in micelle morphologies, using the non-invasive 2D-NOESY technique and molecular modeling. The experimental observations elucidated from computational simulation add novelty to this work. Giving an account to the structural complexity in the three cationic surfactants, the molecular dynamics (MD) simulation was performed for CPB micelles in an aqueous solution of alcohols that highlighted the micelle solvation and structural transition, which is further complemented in terms of critical packing parameter (PP) for the examined systems. 

Biomolecules have been thoroughly investigated in a multitude of solvents historically in order to accentuate or modulate their superlative properties in an array of applications. Ionic liquids have been extensively explored over the last two decades as potential replacements for traditional organic solvents, however, they are sometimes associated with a number of limitations primarily related to cost, convenience, accessibility, and/or sustainability. One potential solvent which is gaining considerable traction in recent years is the so-called deep eutectic solvent which holds a number of striking advantages, including biodegradability, inherently low toxicity, and a facile, low-cost, and solventless preparation from widely available natural feedstocks. In this review, we highlight recent progress and insights into biomolecular behavior within deep eutectic solvent-containing systems, including discussions of their demonstrated utility and prospects for the biostabilization of proteins and nucleic acids, free enzyme and whole-cell biocatalysis, various extraction processes ( e.g. , aqueous biphasic systems, nanosupported separations), drug solubilization, lignocellulose biomass treatment, and targeted therapeutic drug delivery. All indications point to the likelihood that these emerging solvents have the capacity to satisfy the requirements of environmental responsibility while unlocking biomolecular proficiency in established biomedical and biotechnological pursuits as well as a number of academic and industrial ventures not yet explored. 

Biological processes often take place at surfaces of proteins, where the dynamic and structural properties of aqueous solvents are modified. Information about solvent properties including hydration dynamics and structure, and protein collective motions can be obtained by measuring directly the dielectric response in the megahertz to terahertz frequencies of aqueous protein solutions. Due to the strong absorption of water in this frequency range, the experiment is challenging. Our home built dielectric spectrometer using a vector network analyzer together with frequency extenders allows us to perform the experiment in a wide range of frequency from megahertz to terahertz with a high dynamical range up to 120 dB. A detailed investigation of the dielectric response has revealed the hydration structure including the tightly, loosely bound layers and the number of water molecules in each hydration layer. These water molecules relax with different time constants at different temperatures. As a result, the dynamics of hydrated protein is also probed at different temperatures. Understanding the hydration structure and dynamics of lysozyme in biological conditions can explain the enzymatic activities of biomolecules. 

The enzyme Candida Antarctica lipase B (CALB) serves here as a model for understanding connections among hydration layer dynamics, solvation shell structure, and protein surface structure. The structure and dynamics of water molecules in the hydration layer were characterized for regions of the CALB surface, divided around each α-helix, β-sheet, and loop structure. Heterogeneous hydration dynamics were observed around the surface of the enzyme, in line with spectroscopic observations of other proteins. Regional differences in the structure of the biomolecular hydration layer were found to be concomitant with variations in dynamics. In particular, it was seen that regions of higher density exhibit faster water dynamics. This is analogous to the behavior of bulk water, where dynamics (diffusion coefficients) are connected to water structure (density and tetrahedrality) by excess (or pair) entropy, detailed in the Rosenfeld scaling relationship. Additionally, effects of protein surface topology and hydrophobicity on water structure and dynamics were evaluated using multiregression analysis, showing that topology has a somewhat larger effect on hydration layer structure–dynamics. Concave and hydrophobic protein surfaces favor a less dense and more tetrahedral solvation layer, akin to a more ice-like structure, with slower dynamics. Results show that pairwise entropies of local hydration layers, calculated from regional radial distribution functions, scale logarithmically with local hydration dynamics. Thus, the Rosenfeld relationship describes the heterogeneous structure–dynamics of the hydration layer around the enzyme CALB. These findings raise the question of whether this may be a general principle for understanding the structure–dynamics of biomolecular solvation.