Oxygen biosensor based on bilirubin oxidase immobilized on a nanostructured gold electrode

• Gold nanoparticle modified electrodes support diazonium–thiol mixed monolayers.
• Bilirubin oxidase was immobilized on its surface in direct electron transfer regime.
• First-ever BOx DET-based O2-biosensor works in a linear range of 6–300 μM.
• The biosensor performs in presence of inhibitors typical for physiological fluids.

Gold disk electrodes modified with gold nanoparticles have been used as a scaffold for the covalent immobilization of bilirubin oxidase. The nanostructured bioelectrodes were tested as mediator-less biosensors for oxygen in a buffer that mimics the content and the composition of human physiological fluids. Chronoamperometry measurements showed a detection limit towards oxygen of 6 ± 1 μM with a linear range of 6-300 μM, i.e. exceeding usual physiological ranges of oxygen in human tissues and fluids. The biosensor presented is the first ever-reported oxygen amperometric biosensor based on direct electron transfer of bilirubin oxidase.