Macroscopic porosity generation in outer hydrogel membranes to offset sensitivity loss in implantable glucose sensors

The function of implantable glucose sensor is hindered by post-implantation effects such as biofouling and negative tissue responses both of which lead to permeability reducing fibrous encapsulation. Utilization of drug-eluting composite coatings based on dexamethasone-containing poly (lactic-co-glycolic) acid (PLGA) microspheres and poly (vinyl alcohol) (PVA) hydrogel matrix has been shown to suppress inflammation over a period of 1–3 months. Herein, it is shown that these coatings provide another auxiliary venue to offset the negative effects of protein adsorption through generation of macroscopic porosity following microsphere degradation. Long-term studies in serum have indicated that, while biofouling clogs the microporosity of the hydrogel, it has been offset by the generated macroscopic porosity following microsphere degradation. This resulted in a two-fold recovery in sensor sensitivity as compared to controls. These findings suggest that the use of macroscopic porosity can reduce biofouling-induced sensitivity losses, an approach synergistic with drug-delivery based methodologies to mitigate negative tissue responses.