Carbon nanotube-modified biocatalytic microelectrodes with multiscale porosity

Macropores were introduced into nanotube matrices via polystyrene bead templates, and the resulting matrix was applied to carbon fiber microelectrodes as a porous medium for immobilization of enzymatic biocatalysts. The macropores were found to increase the electrochemically active surface area by twofold at a nominal polystyrene mass fraction of 73%. The modified electrodes were further coated with biocatalyst hydrogel comprising glucose oxidase, redox polymer, and crosslinker to create a glucose oxidizing bioanode. Glucose oxidation current density also increased two fold after introduction of the macropores. Focused ion beam cut cross-sections reveal complete adsorption of the enzyme-hydrogel matrix into the CNT layer. This templating technique is a promising approach to the maximization of surface area and transport in bioelectrodes.