Effect of Polyethylene Glycol on Bis(2-hydroxyethyl) terephthalate-Based Polyurethane/Alginate pH-Sensitive Blend for Oral Protein Delivery

Abstract

Polyurethanes (PUs) are synthesized by reacting two polyols, namely bis(2-hydroxyethyl) terephthalate (BHET) and polyethylene glycol (PEG), taken in four different ratios and hexamethylene diisocyanate, where the polyol content is slightly higher than the stoichiometrically required amount. BHET is obtained by the glycolysis of polyethylene terephthalate waste. The synthesized PUs are blended with sodium alginate in the ratio of 7:3 and then cross-linked by calcium chloride to get a pH-sensitive protein (bovine serum albumin, BSA) carrier. X-ray diffraction patterns of different PU compositions indicate the presence of amorphous phase. The hydroxyl value of OH-terminated PUs is found to be increasing with increasing amount of PEG in the composition. PEGylated PU shows higher water uptake and protection against hemolysis with a rising amount of PEG in the PU. Fourier transform infrared spectroscopy of the blend shows characteristic peaks for both PU and alginate distinctly, indicating good dispersion of both the polymers. pH responsive swelling behavior in different pH media corresponding to the gastrointestinal tract (pH 1.2 and 7.4) is investigated for all the prepared blends. The minimum degree of swelling is observed for PU with the maximum amount PEG at pH 1.2, whereas the degree of swelling of the same PU significantly increased at pH 7.4. BSA encapsulation efficiency of the blends increases with an increase in PEG content in the PU and varies within the range of 88-99%. The release profile of BSA at pH 7.4 is found to be similar as observed in the swelling study. © 2015 Wiley Periodicals, Inc.