Transport study of macromolecules through microporous poly(2-hydroxyethyl methacrylate) sponges

Drug transport through polymeric membranes is an important consideration in designing drug delivery systems using polymer matrices. In this study, the transport properties of macroporous sponges formed from poly(2-hydroxyethyl methacrylate) (PHEMA) have been studied. In addition to the in vitro study of insulin release from the PHEMA sponges, the permeation of glucose and macromolecules, such as fluorescein-labelled dextrans, albumin and immunoglobulin G (IgG), through the PHEMA sponges has been investigated. The results suggest that glucose and insulin travel freely through PHEMA sponges and IgG transport is minimized. The microstructure of the PHEMA networks have been characterized using scanning electron microscopy (SEM), in which the PHEMA sponges were observed to contain a multitude of pores and water channels in the porous structure. A biocompatibility study was performed by implanting the sponges into rats for one year. From histological evaluation of the explanted sponges, we observed that all sponges implanted had no effects on the surrounding tissues. In addition, the appearance of the ingrowth of foreign body granulation tissue with neovascularization was also observed. These results indicate that it may be possible to use PHEMA sponges for an implantable device, which controls drug transport.