Pectin hydrogels, aerogels, cryogels and xerogels: Influence of drying on structural and release properties

Pectin is an appealing material for biomedical applications because of its biocompatibility, bioactivity, biodegradability as well as its gelling and stabilizing properties. In this work, porous pectin cryogels, aerogels and xerogels were prepared via freeze-drying, sc drying and evaporative drying at 60 degrees C under low vacuum, respectively, starting from the same pectin precursor, a hydrogel. The physico-chemical and structural properties of the porous pectin matrices were investigated and related to the preparation conditions. The release of the model hydrophilic respiratory drug theophylline from all pectin networks, including the hydrogel, was studied and related to the network morphology and erosion profiles. The Korsmeyer-Peppas and Peppas-Sahlin models were used to determine the main physical mechanisms controlling the release. The release of theophylline can be tuned via the mode of pectin crosslinking in the initial hydrogel as well as via the drying method, demonstrating the potential of porous pectin matrices for drug delivery purposes.