An unforeseen feature of water as a biological fluid is demonstrated. Hyaluronan, a highly hydrated natural biopolymer, has an impact on the structure of water molecules in its extended hydration shells.

In this work, we explored the extended hydration shell structure of hyaluronan in aqueous solutions . Hyaluronan is a highly hydrated biopolymer found in the extracelular environment, such as synovial fluid between joints. Angle-resolved fs-ESHS measurements and nonlinear optical modeling show that hyaluronan behaves like a flexible chain surrounded by extended shells of orientationally correlated water. The spatial extent of the hydration shell is determined via temperature-dependent measurements and can reach up to 475 nm. (read more…)

Cationic Hofmeister series on the ion – macromolecule interactions is finally making sense!

In a recent collaborative work, the molecular mechanism of the interactions between macromolecules and Hofmeister cations is elucidated. Although all metal cations are on average depleted from the macromolecule/water interface, more strongly hydrated metal cations (Ca2+, Mg2+) are able to locally accumulate around the amide oxygen. Such weakly favorable interactions aided partially offset of the salting-out effect. Surprisingly, the cations approach the interface together with chloride counter anions as solvent-shared ion pairs. (read more…)

A new article on exploring the surface propensity of molecular ions in ionic liquid mixtures.

In this study, in collaboration with Suzer Lab, we have demonstrated the surface propensity of TFSI anion over BF4 anion in mixture of ionic liquids. We have developed a new methodology including measurements of angle-resolved X-Ray photoelectron spectroscopy and contact angle along with a signal attenuated modeling to report on the specific surface enrichment of different species in liquid mixtures. This new multi-instrumental method is applicable to various liquid systems. (Read more)

Dr. Okur is awarded the Marie-Curie Fellowship grant.

Dr. Okur has been awarded the Marie Sklodowska-Curie Action (MSCA) Individual Fellowship grant for two years. This is the 9th such grant awarded to a researcher at Bilkent.

Dr. Okur has proposed to elucidate chemical processes occurring at biological surfaces by probing the adjacent interfacial water molecules using nonlinear optical techniques. While the leading scientific approach to investigating biological surfaces has been incorporating dye molecules to probe their optical response, Dr. Okur has adapted an alternative, non-invasive approach: employing water molecules as a probe to report on the chemical processes at these biosurfaces. The underlying motivation is that biological surfaces, being naturally bathed in aqueous solutions, are always in contact with the adjacent water molecules; such a method can thus be applied to almost all biosurfaces.