Space-oriented immobilization of fully active laccase on PPy-ferromagnetic nanoparticles composite layer

Immobilization of paramagnetic molecule of laccase (Lac) under influence of external magnetic field was performed to enhance catalytic activity of the enzyme. A thin layer of composite containing ferromagnetic nanoparticles: carbon-encapsulated iron nanoparticles (Fe@CNps) embedded in electrochemically polymerised PPy film was used for focusing external magnetic field in a space close to the electrode. It was found that magnetic interactions between paramagnetic centres of macromolecules and Fe@C Nps enhance catalytic performance probably by decreasing the gap between the surface of the electrode and active sides of the enzyme. Catalytic efficiency of immobilized enzyme (laccase separated from the fungus Trametes versicolor) was evaluated by the investigation of its ability to bioelectrocatalytic oxygen reduction. For characterization of the composite layers electrochemical gravimetric techniques, inductively coupled plasma mass spectrometry with laser ablation and scanning electron microscopy have been used. Electrochemical experiments performed in the absence and presence of magnetic field indicated significantly higher activity of enzyme and strong enhancement of oxygen reduction current in presence of external magnetic field. It is clear that proposed method helps to maintain enzyme in its highly electroactive form allowing direct electron transfer (DET) between the electrode and the enzyme.