Screen-Printed Carbon Electrodes Modified by Rhodium Dioxide and Glucose Dehydrogenase

Abstract

The described glucose biosensor is based on a screen-printed carbon electrode (SPCE) modified by rhodium dioxide, which functions as a mediator. The electrode is further modified by the enzyme glucose dehydrogenase, which is immobilized on the electrode's surface through electropolymerization with m-phenylenediamine. The enzyme biosensor was optimized and tested in model glucose samples. The biosensor showed a linear range of 500–5000 mg L−1 of glucose with a detection limit of 210 mg L−1 (established as 3σ) and response time of 39 s. When compared with similar glucose biosensors based on glucose oxidase, the main advantage is that neither ascorbic and uric acids nor paracetamol interfere measurements with this biosensor at selected potentials.

Simple and Rapid Determination of Ethanol Content in Beer Using an Amperometric Biosensor

“…As reported previously [26,27], attention needs to be paid to execute the immobilization correctly when dehydrogenases are to be used. Not only enzymes, but also their cofactors (NAD + or NADP + ) are water-soluble.…”

“…Plotting the current response against the input potential, it was observed [27] that oxidation starts at around +0.2 V, and with increasing potential the response increases too [27]. No catalytic activity was observed in the potential range of −0.05 to +0.15 V, which implies that, to determine ethanol, an appropriate potential should be chosen in the range of +0.2 to +0.6 V. As shown [26], possible interfering species (both ascorbic and uric acids) are electroactive if the potential of +0.5 V is applied but their responses are negligible at potentials from −0.2 to +0.45 V. Formerly, effects of flow rate and pH were also studied [26]. At optimum conditions (batch volume, 200 µL; input potential, +0.25 V; flow rate, 0.6 mL•min −1 ), a calibration dependence of the biosensor response to ethanol was studied.…”

“…A screen-printed carbon electrode (SPCE) was used as a support for a biosensor, which was prepared similarly as described previously: carbon ink (0.095 g, Gwent C50905D1, Pontypool, UK) and rhodium dioxide (0.05 g) were thoroughly mixed and subsequently sonicated; the mixture was used for screen-printing to obtain a SPCE/RhO2 support [26] on which the enzyme was immobilized. Measurements were performed by direct current amperometry in both flow injection and batch arrangements.…”

“…Measurements were performed by direct current amperometry in both flow injection and batch arrangements. All operational variables (i.e., applied potential, pH and flow rate) were optimized [26,27]. It should be noted that all of the prepared and used biosensors were stored in the fridge to keep their long term stability; their activities retained constant even after 60 injections, and that no loss of the original responses occurred after three weeks of measurements.…”

“…In addition, its stability in flow injection analytical procedures was absolutely satisfactory. Subsequently, we reported on screen-printed biosensors modified by RhO2 and dehydrogenases [26,27], and determination of ethanol in alcoholic drinks like wine, vodka and whisky was also tested [27]. This biosensor worked even at low input potentials, where other easily oxidable or reducible molecules often present in real samples did not contribute to resulting amperometric signals.…”