Gold nanoparticles in nonenzymatic electrochemical detection of sugars

A nonenzymatic electrochemical sensor for detection of sugars was prepared by layer-by-layer deposition of gold nanoparticles on thin gold electrodes. The deposition was optimized by using of surface plasmon resonance. Voltammetric investigation and impedance spectroscopy of the sensor was performed. Electrical currents caused by glucose on bare gold electrodes and on gold electrodes coated by immobilized gold nanoparticles were compared. The electrodes with nanoparticles display much higher current of glucose oxidation. The oxidation becomes blocked when the swept electrode potential exceeded +0.25 V, during the back scan an oxidation peak is observed again but at less positive potential. The magnitudes of these current peaks are linearly dependent on the glucose concentration; this dependence can be used as calibration for analytical applications. The limit of detection for glucose is below 0.5 mM, the sensitivity (normalized to the macroscopic electrode surface) is about 160 μA cm^-2 mM^-1. The sensor response is linear till at least 8 mM of glucose concentration.