Optimum Copper-Palladium Catalyst from a Combinatorial Library for Sensitive Non-Enzymatic Glucose Sensors

The optimum activity for glucose electrocatalytic oxidation was found by screening along a large spread co-sputtered combinatorial copper-palladium library (2.6 at.% to 39.2 at.% Pd) in neutral media using flow-type scanning droplet cell microscopy (FT-SDCM). The elemental composition and the surface topography were characterized along the compositional spread using energy dispersive X-ray spectroscopy (EDX), as well as atomic force microscopy (AFM). The study proves that the entire range of alloys can be implemented in glucose detection. The highest catalytic effect was obtained at a Pd content of 8.2 at.% (E-SHE = 0.58 V) with a current density value of 7.33 mA cm(-2). The suitability for being used as quantitative and qualitative glucose sensor was demonstrated. The calibration performed in phosphate buffer solution containing different amounts of glucose revealed two linear regions with different sensitivities towards the quantitative glucose detection. The highest sensitivity was determined in the range of 0-25 mM glucose, which is indicated by an increase of 81.2 mu A cm(-2) mM(-1), normalized to the stepwise increase of 1 mM glucose. Also, a good long-term stability, reproducibility (relative standard deviation similar to 5%), as well as the selective sensitivity to glucose oxidation were demonstrated by performing measurements in the presence of other compounds found in blood (e.g., ascorbic acid and uric acid).