Poly(o-phenylenediamine) ultra-thin polymer-film composite membranes for enzyme electrodes

An ultra-thin poly(o-phenylenediamine) film composite membrane has been used as the outer covering barrier in an amperometric glucose oxidase enzyme electrode. The composite membrane was formed via the electropolymerisation of o-phenylenediamine dihydrochloride at a gold sputter-coated porous polycarbonate membrane. Homogeneous poly(o-phenylenediamine) films of approximately 30 nm thickness acted as an effective diffusional barrier and were supported by the underlying host gold-coated polycarbonate membrane. Oxygen and glucose permeability coefficients were determined using diffusion chamber apparatus. Composite membranes of this type were also found to offer some permselective screening of anionic interferent solutes such as ascorbate. On exposure to whole blood, a 30% signal drift with time was observed over a period of 1 h; after this time responses remained almost stable. Whole blood glucose determinations compared with standard hospital laboratory analyses showed a close correlation (r2=0.92).