While the liquid–liquid phase separation (LLPS) process in proteins has been studied in great detail, it has not been widely explored how the associated protein hydration changes during the process and how crucial its role is in the process itself. In this contribution, we experimentally explore the alteration of lysozyme hydration during its LLPS process using attenuated total reflection (ATR)-FTIR spectroscopy in the THz frequency region (1.5–21 THz). Additionally, we explore the role of excipients (l-arginine, sucrose, bovine albumin (BSA), and ubiquitin (Ubi)) in regulating the process and found that, while sucrose stabilizes the LLPS, BSA inhibits it. The effect of Arg in the LLPS is subtle, and that of Ubi is concentration dependent. We made a detailed analysis of the hydration profile of Lys in the presence of these excipients and observe that a change in hydration in terms of H-bond making/breaking is a definite signature regulating the process.

Polymer/surfactant composites have emerged as a subject of interest for their diverse applications. The improved solution properties in polymer/surfactant composites have been correlated to the formation of premicellar surfactant aggregate-polymer complexes (PS) at a surfactant concentration well below their critical micelle concentrations. Using different physicochemical and spectroscopic techniques here we have studied PS formed by hydroxypropyl cellulose, a nonionic-biocompatible polymer, and alkyl sulfate surfactants of different tail lengths. Our study shows that an increase in surfactant tail length eases PS formation and enhances PS-induced polymer cross-linking and, correspondingly, solution viscosity. PS consisting of shorter tail surfactants and those with longer tail surfactants differ microscopically as the former offers more polar interior than the later as evidenced from fluorescence measurements. Our study establishes that shorter tail surfactants intend to stay loosely packed inside PS and allow larger water penetration, which creates a relatively polar hydrophobic core compared to the PS with longer tail surfactants. The stronger packing of PS with longer tail surfactants is an outcome of favorable interaction between polymer polar groups and surfactant headgroups, which further creates strongly hydrogen-bonded water in their hydration shell.

Using terahertz spectroscopy, we established the alteration of the collective hydration of water during the fibrillation process (native → intermediate → fibril) of a model protein bovine serum albumin.

Cholesterol is known to modify the phase behavior of model lipid membranes as it makes phospholipid bilayer more structured. Simulation results have shown that addition of cholesterol allows more bulk...

Cells are crowded with various cosolutes including salts, osmolytes, nucleic acids, peptides and proteins.