Hydrophobically modified poly(vinyl alcohol) and boric acid-containing monoolein cubic phase as a glucose-responsive vehicle

Abstract

Glucose-responsive monoolein (MO) cubic phase was prepared by including hydrophobically modified poly(vinyl alcohol) (HmPVA) and boric acid in its water channels. The covalent attachment of hexanoyl chloride (a hydrophobic modifier) to PVA was confirmed by 1H NMR and FT-IR spectroscopy. The viscosity of HmPVA/boric acid mixture solution (0.5% (HmPVA w/v)) in water/DMSO(1:1, v/v) increased significantly when the boric acid concentration increased to 3.2% (w/v). The viscosity of the HmPVA/boric acid mixture solution (0.5% (w/v)/0.8% (w/v)) decreased markedly when the glucose concentration increased to 400mg/dL. The interfacial tension in the plateau region of HmPVA solution, about 42dyn/cm, was lower than that of PVA solution, about 43dyn/cm, suggesting that HmPVA was more surface-active than PVA. According to the polarized optical microscopy, the phase transition temperature was found to be about 49.8°C. The release degree of amaranth (a dye) loaded in MO cubic phase containing HmPVA and boric acid was higher at a higher glucose concentration in the range of 0mg/dL⿿400mg/dL.