Thermoresponsive hydrogels with covalently incorporated trehalose as protein carriers

A series of thermoresponsive hydrogels containing covalently incorporated trehalose, the well-known protein stabilizing disaccharide, was synthesized with the aim to obtain bioprotective carriers for protein release. Smart materials with trehalose present only in cross-links or both in cross-links and as pending moieties, were fabricated by redox-initiated radical copolymerization, with N-isopropylacrylamide used as the main monomer. In order to modify thermoresponsive properties, hydrogels containing more hydrophilic comonomers, acrylamide or N-(2-hydroxyethyl)acrylamide, were also obtained. The susceptibility of the cross-linker to undergo acid-catalyzed hydrolysis was used to disintegrate the polymer network and estimate the composition of the synthesized materials. The properties of hydrogels, which include: swelling capacity, thermoresponsive behavior, rheological characteristic, internal microstructure and the rate of acid-catalyzed degradation, were found to be dependent on both trehalose as well as hydrophilic comonomers. BSA and β-Galactosidase were chosen as model proteins for the release study from obtained hydrogels. The release profiles were shown to vary significantly depending on hydrogel form, the polymer network composition and temperature.