title: Self-cleaning membrane to extend the lifetime of an implanted glucose biosensor.
abstract: The lifetime and efficacy of a subcutaneously implanted glucose biosensor could be greatly improved by a self-cleaning membrane capable of periodic physical removal of adhered cells associated with the foreign body reaction. Previously, we reported a thermoresponsive double network nanocomposite (DNNC) membrane composed of poly(N-isopropylacrylamide) (PNIPAAm) and embedded polysiloxane nanoparticles. When the membrane was thermally cycled above and below its volume phase transition temperature (VPTT, ~33-35 °C), the associated deswelling and reswelling, respectively, led to in vitro cell release. Herein, this membrane design was tailored to meet the specific demands of a subcutaneously implanted glucose biosensor, and critical functional properties were assessed. First, N-vinylpyrrolidone (NVP) comonomer increased the VPTT to ~38 °C so that the membrane would be swollen and thus more permeable to glucose in the "off-state" (i.e., no heating) while residing in the subcutaneous tissue (~35 °C). Second, glucose diffusion kinetics though the DNNC membrane was experimentally measured in its deswollen and reswollen states. A cylindrical DNNC membrane with dimensions considered suitable for implantation (1.5 × 5 mm, diameter × length) was used to model the glucose diffusion lag time. In addition, the DNNC cylinder was used to observe dimensional changes associated with deswelling and reswelling. Noncytotoxicity was confirmed and self-cleaning was assessed in vitro in terms of thermally driven cell release to confirm the potential of the DNNC membrane to control biofouling.
authors.affiliation: Department of Biomedical Engineering, Texas A&M University , College Station, Texas 77843-3120, United States.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Abraham
authors.forename: Ruochong
authors.initials: R
authors.lastname: Fei
authors.forename: Gerard L
authors.initials: GL
authors.lastname: Coté
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Grunlan
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D057219:Biofouling / Q000517:prevention & control; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000592:standards; D005947:Glucose / Q000032:analysis*; D020100:Hydrogels / Q000737:chemistry; D053761:Nanocomposites / Q000737:chemistry; D044367:Phase Transition; D012833:Siloxanes / Q000737:chemistry; D044366:Transition Temperature
chemical_list: D000180:Acrylic Resins; D020100:Hydrogels; D012833:Siloxanes; C052970:poly-N-isopropylacrylamide; D005947:Glucose