A membrane that limits biofouling is critical to extend the lifetime and efficacy of implanted glucose biosensors. When cycled above and below its volume phase transition temperature (VPTT, ~33 °C), poly(N-isopropylacrylamide) (PNIPAAm) hydrogels undergo deswelling and reswelling, respectively. This process is known to effectively remove adhered proteins and cultured cells in vitro. We propose that a PNIPAAm-based hydrogel membrane could control biofouling in vivo via a “self-cleaning” mechanism induced by thermal cycling. This approach is feasible if the membrane can be designed with rapid deswelling/swelling kinetics for efficient cell release, adequate mechanical properties for implantation and also sufficient glucose diffusion. In this work, several parameters were explored to achieve these properties including, incorporation of polysiloxane nanoparticles, a double network hydrogel matrix design and incorporation of an electrostatic or zwitterionic comonomer. The impact of these design variables on key membrane properties were assessed, including: deswelling/reswelling behavior (gravimetric and differential scanning calorimetry - DSC), morphology (SEM) and modulus & strength (compression tests). Thermally-driven in vitro cell release and a pre-clinical pilot study demonstrated encouraging results in terms of membrane self-cleaning behavior.

Thermoresponsive hydrogels as self-cleaning membranes for implanted glucose biosensors

254th National Meeting (2017)

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