Transport properties of pHEMA membranes for optical glucose affinity sensors

Crosslinked poly(2-hydroxyethyl methacrylate) (pHEMA) membranes, in flat sheet and tubular forms, were prepared and evaluated as candidates to be used in conjunction with optical glucose affinity assays for potential transdermal glucose detection. Permeation experiments were performed in vitro with creatinine (113 Da) and IgG-Fab fragment (50 kDa) through pHEMA membranes with varying amounts of the crosslinker ethylene glycol dimethacrylate (EGDMA). Increasing the amount of crosslinker decreases the water content with the expected decrease in creatinine permeability and increase in selectivity for creatinine over the protein. Membranes prepared with 4% EGDMA (mol/mol monomer) demonstrated substantially better selectivity than 1000 MWCO dialysis membranes. Tubular membranes were implanted subcutaneously in rats to determine the host response. Membrane clarity and integrity were maintained for the duration of the 6 week implantation, with minimal (∼40 μm thick) fibrotic capsule formation on the external surface.