Development of a self-cleaning sensor membrane for implantable biosensors

Fibrous tissue encapsulation may slow the diffusion of the target analyte to an implanted sensor and compromise the optical signal. Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels are thermoresponsive, exhibiting temperature-modulated swelling behavior that could be used to prevent biofouling. Unfortunately, PNIPAAm hydrogels are limited by poor mechanical strength. In this Study, a unique thermoresponsive nanocomposite hydrogel was developed to create a mechanically robust Self-cleaning sensor membrane for implantable biosensors. This hydrogel was prepared by the photochemical cure of all aqueous solution of NIPAAm and copoly(dimethylsiloxane/ methylvinylsiloxane) colloidal nanoparticles (similar to 219 nm). At temperatures above the volume phase transition temperature (VPTT) of approximately 33-34 degrees C, the hydrogel des-wells and becomes hydrophobic, whereas lowering the temperature below the VPTT causes the hydrogel to swell and become hydrophilic. The potential of this material to minimize biofouling via temperature-modulation while maintaining sensor viability was investigated using glucose as a target analyte. PNIPAAm composite hydrogels with and without poration were compared to a pure PNIPAAm hydrogel and a nonthermoresponsive poly (ethylene glycol) (PEG) hydrogel. Poration led to a substantial increase in diffusion. Cycling the temperature of the nanocomposite hydrogels around the VPTT caused significant detachment of GFP-H2B 3T3 fibroblast cells. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 90A: 695-701,2009