OXYGEN-TRANSPORT CHARACTERISTICS OF REFUNCTIONALIZED FLUOROPOLYMERIC MEMBRANES AND THEIR APPLICATION IN THE DESIGN OF BIOSENSORS BASED UPONTHE CLARK-TYPE OXYGEN PROBE

Surface refunctionalized fluoropolymer membranes were applied in the d esign of whole cell and enzyme biosensors based on the Clark-type oxyg en sensor, Fluoropolymer membranes (poly(hexafluoropropylene-co-tetraf luoroethylene) (FEP)) were treated using a recently developed procedur e that employs a hydrogen/methanol vapor radio frequency glow discharg e plasma to introduce hydroxyl functionality into the polymer backbone in a controlled fashion. Hydroxylated materials were aminated by trea tment with (gamma-aminopropyl)triethoxysilane (APTES). The surface ami ne groups served as attachment sites for whole cells and enzymes. Init ial work measured the permeability and diffusion coefficients for oxyg en in hydroxylated, aminated, and base (nonmodified) FEP membranes, Re functionalized membranes retained the oxygen permeability and diffusio n characteristics of the base fluoropolymer. Subsequent experiments in vestigated the response of biosensors constructed using aminated FEP a s the gas-permeable membrane of a Clark-type oxygen sensor. The respir ation of NB2a neuroblastoma cells was recorded following cell attachme nt to the membrane through natural growth processes. In a quiet soluti on, the response of the oxygen sensor decreased by similar to 40% in t he presence of a monolayer of respiring cells. Sensor response slowly returned to baseline after the cells were exposed to millimolar levels of sodium azide. The response of an enzyme electrode, constructed by linking glucose oxidase and albumin to free amine sites of aminated FE P, is also demonstrated. The calibration curve for glucose was linear over a concentration range between 0.1 and 6.5 mM, and the sensor resp onse reached a steady state within about 60 s of exposure to glucose.