Encapsulation of the quercetin with interpolyelectrolyte complex based on pillar[5]arenes

Abstract

The using of pH-sensitive delivery systems is a promising strategy to significantly improve the pharmacological properties of water-insoluble drugs. Herein, we propose and develop an approach to synthesis of interpolyelectrolyte complexes based on combination of two water-soluble decasubstituted non-toxic pillar[5]arenes for encapsulation poor-soluble quercetin and its subsequent release depending on the pH. Interpolyelectrolytes were obtained by mixing aqueous solutions one of which contained a polycationic (ammonium) and the other - a polyanionic (carboxylate) components. The shape and size evolution of interpolyelectrolytes were studied by dynamic light scattering and transmission electron microscopy. Spherical aggregates with an average diameter of 10 nm are found. The ability to form complexes and associates with quercetin by polycationic and polyanionic macrocycle, as well as an interpolyelectrolyte complex based on them, was studied by electron UV–vis and fluorescence spectroscopy, dynamic light scattering. Interpolyelectrolyte complex more efficiently binds quercetin (pKa 5.13) compared with individual macrocycles due to the greater stability of the associates formed by IPEC. The release of quercetin from the interpolyelectrolyte complex was studied in acidic (pH = 4.00), weakly acidic (pH = 5.00–5.50), neutral (pH = 7.44) and weakly alkaline (pH = 8.15) solutions. It was found the full release of the quercetin without oxidation of flavonoid is observed in the neutral solution. This work provides important guidance for the design of successful delivery systems via optimizing the structure and composition of nanocapsules.