A paper-based nanomodified electrochemical biosensor for ethanol detection in beers

Herein, we report the first example of a paper-based screen-printed biosensor for the detection of ethanol in beer samples. Common office paper was adopted to fabricate the analytical device. The properties of this paper-based screen-printed electrode (SPE) were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy, and they were compared with the well-established polyester-based SPEs as well. Paper demonstrated similar properties when compared with polyester, highlighting suitability towards its utilization in sensor development, with the advantages of low cost and simple disposal by incineration. A nanocomposite formed by Carbon Black (CB) and Prussian Blue nanoparticles (PBNPs), namely CB/PBNPs, was utilized as an electrocatalyst to detect the hydrogen peroxide generated by the enzymatic reaction between alcohol oxidase (AOx) and ethanol. After optimizing the analytical parameters, such as pH, enzyme, concentration, and working potential, the developed biosensor allowed a facile quantification of ethanol up to 10 mM (0.058 %vol), with a sensitivity of 9.13 μA/mM cm2 (1574 μA/%vol cm2) and a detection limit equal to 0.52 mM (0.003%vol). These satisfactory performances rendered the realized paper-based biosensor reliable over the analysis of ethanol contained in four different types of beers, including Pilsner, Weiss, Lager, and alcohol-free. The proposed manufacturing approach offers an affordable and sustainable tool for food quality control and for the realization of different electrochemical sensors and biosensors as well.