Tuning the self-assembly of EO-PO block copolymers and quercetin solubilization in the presence of some common pharmacuetical excipients: A comparative study on a linear triblock and a starblock copolymer

Here we report, the effect of biologically important additives such as glucose, glycine, sodium chloride, urea and ethanol on the clouding and micellar behaviour of two commercially available ethylene oxide-propylene oxide (EO-PO) block copolymers (one linear triblock, Pluronic (R) P104 and other branched, starblock Tetronic (R) T1304) in aqueous environment. The cloud point (CP), viscosity, and dynamic light scattering (DLS) were measured. The solubilization of poorly water soluble drug, quercetin (QN) was also checked for the copolymer micelles in the presence of these additives using UV-visible spectroscopy. These additives depending upon their structure either decrease or increase CP and hydrodynamic diameter (Dh). Salt, glucose and glycine favoured micellization while urea and ethanol showed opposite behaviour. Markedly enhanced solubilization of QN was observed by the copolymer micelles which further improved in the presence of salt, glucose and glycine but decreased in the presence of ethanol and urea. The conclusions derived from this work will be highly useful in optimizing the performance of the copolymers in different pharmaceutical applications and in drug delivery systems as drug carriers. (C) 2017 Elsevier B.V. All rights reserved.