Bimetallic nano-structured glucose sensing electrode composed of copper atoms deposited on gold nanoparticles

We describe the preparation and sensing capabilities of a bimetallic electrode consisting of copper atoms deposited on gold nanoparticles (GNPs). The electrode was obtained by first constructing a GNP template on the surface of a glassy carbon electrode by exploiting the hydrogen-bonding interactions between pyridine groups on the surface of the GNPs and the carboxy groups of poly (acrylic acid). GNPs (60 nm in diameter) were homogeneously and densely deposited in the template (as revealed by scanning electron microscopy). The electro-deposition of copper ad-atoms on GNPs occurred at an underpotential and was proven by electrochemical techniques. The presence of GNPs in the template accelerated the deposition at low potential due to its beneficial effect on the rate of electron transfer. The new electrode was studied for its response to glucose. Highly stable and reproducible catalytic activity towards glucose oxidation is observed and attributed to the synergistic catalytic effect of the copper atoms on the surface of the GNPs. The detection limit is as low as 50 nM (at a signal-to-noise ratio of 3), and the response is between 200 nM and 10 mM of glucose.