Biocompatible carbon nanoparticles were successfully produced during the first period of the project and their use has been extended from the initial scope of the study. The first objective aiming to develop a biocompatible interface has been fully reached, thus providing a reliable method to immobilize the carbon nanoparticles onto a polycrystalline gold substrate. The in- depth characterization of the interface was carried out as planned using atomic force microscopy, high-resolution scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis. The rich surface chemistry of the carbon nanoparticles was also exploited to compare the electrochemical response of biomolecules immobilized in an oriented manner onto the gold electrode. The outcome of the project dealing with the electrochemical activity of redox enzymes has been extended to the catalytic hydrogen evolution reaction, using the newly developed carbon interface