The interaction between biomolecules and ions in aqueous
solutions has a great influence on biological processes [1], and
understanding the behavior of these species is important for
understanding how they function in physiological systems [1].
Furthermore, knowing the thermodynamic properties of biological
systems is important in the engineering and biotechnological
domains. As a biomolecule, urea acts as a protein denaturant and
influences protein folding and protein-DNA binding [2,3]. Also,
urea’s effect on the structure of water has been the subject of
many studies [4]. However, these results are controversial as some
researchers reported that urea is a “structure breaker” [5–7] while
others classify it as a “structure maker” [4]. Density measurements
reveal volume or size effects (entropy) of urea on water. Moreover,
activity and osmotic coefficients directly reflect the molecular
interactions as they contain entropic and enthalpic effects [8]. Urea
and electrolytes are present to a large extent under physiological
conditions. Hence, knowledge about interactions between urea and