Design and Characterization of a PVLA-PEG-PVLA Thermosensitive and Biodegradable Hydrogel.

A set of poly(δ-valerolactone--d,l-lactide)--poly(ethylene glycol)--poly(δ-valerolactone--d,l-lactide) (PVLA-PEG-PVLA) triblock copolymers was synthesized and the solution properties were characterized using rheology, cryo-TEM, cryo-SEM, SANS, and degradation studies. This polymer self-assembles into a low viscosity fluid with flowerlike spherical micelles in water at room temperature and transforms into a wormlike morphology upon heating, accompanied by gelation. At even higher temperatures syneresis is observed. At physiological temperature (37 °C) the hydrogel's average pore size is around 600 nm. The PVLA-PEG-PVLA gel degrades in about 45 days in cell media, making this unique hydrogel a promising candidate for biomedical applications.