Amphiphilic star block copolymer micelles in saline as effective vehicle for quercetin solubilization

There has been an enormous interest in improving the therapeutic efficacy of hydrophobic flavonoids through enhancement of their bioavailability. A carrier capable to effectively solubilize flavonoids is expected to support the chemical/structural integrity of flavonoid molecule, and hence, its antioxidant properties. In this paper, the effectiveness of saline solutions of an amphiphilic star block ethylene oxide-propylene oxide copolymer (Tetronic (R) T904) has been investigated for solubilizing quercetin (QN). T904 self-assembles in aqueous solution above its critical micellization temperature (CMT) that depends on solution concentration, temperature, pH and presence of salt. We have studied the solubilization of QN in T904 micelles at different temperature, concentration and salt (sodium chloride) concentration using scattering and spectral techniques. Our findings suggest that, at a given temperature, QN solubility is influenced by the concentration of salt and copolymer. When compared to its linear counterparts (the Pluronics (R)), T904 solutions offered superior solubilization. 2D NOESY NMR observations revealed that QN occupied the periphery of the hydrophobic core of micelles. Such an environment can protect the drug against oxidation in aqueous phase. (C) 2021 Elsevier B.V. All rights reserved.