• Laccase;
  • Colloidal gold particles;
  • Carbon black;
  • Oxygen reduction;
  • Enzyme immobilization


Functional composites of carbon and gold nanoparticles create a hierarchical architecture that facilitates high enzyme loading. Subsequent immobilization of the multicopper oxidase, Trametes versciolor laccase, was optimal with dithiobis- (succinimidyl propionate), due to the formation of thiol bonds between the protein molecules and gold. The immobilized laccase catalyzed oxygen reduction, with an onset potential of ∼0.6 V (vs. Ag/AgCl), indicated effective orientation of the enzyme redox center to enable direct electron transport between enzyme and the composite electrode. Current densities in half-cell configurations provide scalable outputs of 50–80 µA/cm2 with the optimized electrode design. The methodology herein describes a rapid, facile preparation of gold-decorated carbon composite materials for use as electrode scaffolds that can be integrated into a range of bioelectronic devices.