Characterization of analyte transport over time through implantable biosensor membranes using microdialysis

A microdialysis method for monitoring permeability changes of implanted biosensor membranes was demonstrated in vivo. Glucose diffusion through three different hollow fiber membranes (polyethersulfone (PES), polyacrylonitrile (PAN), polycarbonate (PC)) was assessed over 8 days in rat subcutaneous tissue. There was a 77% decrease of transport through the implanted PES membranes after two days; whereas decreases in PAN and PC were significantly smaller (36% and 26%). Application of a microdialysis transport model indicated the average tissue resistance to glucose transport increased by a factor of 6 causing glucose flux into the microdialysis probes to go down over the 8 day implantation time. Histological analysis and scanning electron micrographs (SEM) show evidence of biofouling and tissue changes that would cause such decreases. The data presented provides an in vivo validation for application of microdialysis to study changes in glucose transport and a quantification of tissue resistance over time around implanted membranes.