UCLA

Thin films of Nafion, p-phenylenediamine (PPD) and crosslinked choline oxidase (ChOx) were coated onto a Pt rotating disk electrode (RDE). A MSR electrode rotator with a three-electrode system was used to evaluate the mass transport properties of hydrogen peroxide (H2O2) within these thin films at room temperature. Diffusion coefficients of H2O2 within Nafion, PPD and crosslinked ChOx were obtained from Koutecky-Levich analysis. The obtained values are (2.4 � 0.2) � 10-7 cm2/s for Nafion, (1.7 � 0.3) � 10-8 cm2/s for PPD and (2.9 � 0.3) � 10-6 cm2/s for crosslinked ChOx using a simple diffusion model. An extensive comparison of the results to many reported in the literature suggests good agreement. These diffusion coefficient estimates provide good parameter values for mathematical models of thin-film coated biosensors that require Nafion and PPD coatings for permselectivity.