Protein and polyelectrolyte layer-by-layer films: Assembly and electron transfer

Abstract: A layer-by-layer deposition technique for assembly of the three-dimensional bioelectrochemical systems, with potential applications such as sensing layers in biosensors or catalytic organisations in biofuel cells, was addressed in this thesis. Several investigations were carried out to understand and control multilayer films formation on planar surfaces, using electrochemical and ellipsometrical methods. Synthetic and natural/biological polymers were used as building blocks in layer-by-layer films construction. Redox enzymes, such as peroxidases and "blue" multicopper oxidases, were incorporated into multilayer assemblies to provide layers with the catalytic functions. Bioelectrocatalytic activity of the enzymes in the layer structures was evaluated by measuring direct and mediated electron transfer rates between the enzymes and assembly supporting electrodes. In order to enhance direct electron transfer properties of the enzymes in layer-by layer films, gold nanoparticles and carbon nanotubes were used for nanowiring of the redox enzymes. It was shown that layer-by-layer deposition techniques enable controlled assembly of nanoparticle-enzyme conjugates on the electrode surfaces. This provided a possibility for evaluating kinetic and thermodynamic characteristics of the heterogeneous electron transfer between the redox enzymes and gold nanoparticles.