Influence of Hofmeister anions on structural and thermal properties of a starch-protein-lipid nanoparticle.

A self-assembled soluble nanoparticle, composed of common food biopolymers (carbohydrate, protein) and lipid, was previously reported by our laboratory. Although carrying capacity of valuable small molecules was demonstrated, physical functional properties are also important. Given the stabilization or destabilization characteristics of Hofmeister anion on macromolecular structures, mainly on proteins, here, we investigated the effects of different sodium salts composed of different Hofmeister anions on the structural and thermal properties of these self-assembled nanoparticles for improved functionalities. The salts were added into the mixture that was prepared in a diluted system during nanoparticle formation. Increased concentration of kosmotropic anions, in contrast to the chaotropic anion tested, resulted in nanoparticles with higher molar mass, hydrodynamic radius, and molecular density with more compact arrangement. The nanoparticles produced in presence of kosmotropic anions dissociated at higher temperatures and required higher enthalpies compared to the control sample. Spherical nanoparticles were formed for the kosmotropes with shear thinning behavior, contrary to rod-like nanoparticles for the chaotrope with near-Newtonian behavior. These findings help to gain an understanding of the effect of altering environmental conditions on the nanoparticles with an aim of producing desired structures for applications.

Solubility enhancement of hydrophobic compounds by cosolvents: role of solute hydrophobicity on the solubilization effect.

Drug solubilization is an important aspect of drug development. We investigate the relationship between solute hydrophobicity on the solubilization properties of water-cosolvent mixtures. The solubilization in water-cosolvent mixtures of seven chemically unrelated drugs was determined. The set of solutes included hydrocortisone, sulfanilamide, acetophenetidine, benzocaine, indomethacin, thymol and ibuprofen. Two sets of water-cosolvent mixtures were used in the study. A group of polar cosolvents consisting of three aliphatic alcohols, and a group of the less polar cosolvents NMP, tetraglycol and labrasol. The hydrophobicity of the drug has a direct impact on the solubilization obtained in the water-cosolvent mixtures. However, the role of hydrophobicity is different in the case of the polar cosolvents compared with the less polar ones. In polar cosolvents, the solubilization behavior is typical of polarity match, where the collective trend of solubility enhancement decreases as the activity coefficient of the solute in the solvent mixture increases. The result is a linear profile comprising the combined data of all solutes and all solvents. On the other hand, while the less polar cosolvents exhibit greater positive deviations from the log-linear cosolvency model, the collective solubility enhancement in these systems exhibits no readily discernible pattern. However, by taking into account the hydrophobicity of the solutes, a systematic effect becomes clearly apparent. In this case, the hydrophobicity of the solute demarcates its region in the solubilization profile.