Characterisation of a two-phase hydrogel system for a potential wound healing application

In this chapter, a two-phase hydrogel was prepared by physically imbedding a xerogel in the core of a cryogel that was freeze thawed. The cryogels were prepared with poly vinyl alcohol (PVA) and poly acrylic acid (PAA) while the xerogels were prepared by UV polymerisation of 1-vinyl-2-pyrrolidinone (NVP), acrylic acid (AA) and various percentages of ibuprofen sodium salt. The mechanical properties were determined by parallel plate rheometry and the thermal properties were determined by differential scanning calorimetry (DSC). The results indicated that the hydrogels containing increasing amounts of PAA are significantly stiffer than those synthesised using PVP alone at test temperatures between 30 and 80 °C. Differential scanning calorimetry (DSC) analysis suggested that thermal transitions occur at temperatures that may make these hydrogels useful as temperature sensitive drug delivery systems. The chemical structure of the hydrogels was confirmed by means of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), while swelling experiments in distilled water indicate that the swelling of the gels is temperature dependent. In all cases, drug dissolution analysis showed that the active agent was released at a slower rate from hydrogels that contained acrylic acid. 2010 by Nova Science Publishers, Inc. All rights reserved.