pH-sensitive and bioadhesive poly(β-amino ester)–poly(ethylene glycol)–poly(β-amino ester) triblock copolymer hydrogels with potential for drug delivery in oral mucosal surfaces

A series of novel pH-sensitive triblock copolymers composed of poly(β-amino ester)–poly(ethylene glycol)–poly(β-amino ester) (PAE–PEG–PAE) were synthesized by conjugating poly(β-amino ester) to poly(ethylene glycol). The resulting polymers were characterized by 1H and 13C NMR in CDCl3 and gel permeation chromatography in tetrahydrofuran. The concentrated polymer solutions (30 wt%) exhibited a gel-to-sol transition in the pH range 6.4–7.8. The gel window spanned physiological conditions (37 °C, pH 7.4). After injection into a rat, the copolymer solution (30 wt%) changed to a gel in a short time. This copolymer hydrogel showed bioadhesive properties and in vitro release of lidocaine was controllable.