Amperometric ethanol biosensor based on poly(vinyl alcohol)–multiwalled carbon nanotube–alcohol dehydrogenase biocomposite

A novel amperometric ethanol biosensor was constructed using alcohol dehydrogenase (ADH) physically immobilized within poly(vinyl alcohol)–multiwalled carbon nanotube (PVA–MWCNT) composite obtained by a freezing–thawing process. It comprises a MWCNT conduit, a PVA binder, and an ADH function. The measurement of ethanol is based on the signal produced by β-nicotinamide adenine dinucleotide (NADH), the product of the enzymatic reaction. The homogeneity of the resulting biocomposite film was characterized by atomic force microscopy (AFM). The performance of the PVA–MWCNT–ADH biocomposite modified glassy carbon electrode was evaluated using cyclic voltammetry and amperometry in the presence of NADH and in the presence of ethanol. The ethanol content in standard solutions was determined and a sensitivity of 196 nA mM−1, a linear range up to 1.5 mM, and a response time of about 8 s were obtained. These characteristics allowed its application for direct detection of ethanol in alcoholic beverages: beer, red wine, and spirit.