Preparation and characterization of macroporous Poly(N-isopropylacrylamide) hydrogels for the controlled release of proteins

Macroporous, temperature-sensitive poly(N-isopropylacrylamide) (PNIPA-Am) hydrogels were synthesized with poly(ethylene glycol)s (PEGS; molecular weight = 2000-6000) as the pore-forming agents. The influence of the molecular weight and PEG content on the responsive kinetics of these macroporous hydrogels was investigated. The PEG-modified PNIPAAm hydrogels were characterized by the swelling ratio, deswelling-reswelling kinetics, Fourier transform infrared, and differential scanning calorimetry. The morphology of these hydrogels was analyzed with scanning electron microscopy. The prepared macroporous hydrogels exhibited some unique proper-ties in comparison with the gels with low molecular weight PEGS (molecular weight < 2000) as the pore-forming agents. In addition, a preliminary study on the controlled release of bovine serum albumin from these macroporous hydrogels was carried out. (C) 2002 Wiley Periodicals, Inc.