Gas sensor for 4-ethylguaiacol detection based on tyrosinase enzymatic activity in a deep eutectic solvent

The use of environmentally friendly, cost-effective and biodegradable deep eutectic solvents (DESs) as nonaqueous solvents and electrolytes offers a promising avenue for enhancing enzymatic sensors and extending their applicability to the gas phase. In this study, an assembly is presented that includes a paper crown modified with tyrosinase enzyme, soaked in a DES and positioned on a disposable screen-printed carbon electrode. The paper crown contacts the outer edge of the carbon disk working electrode, as well as the peripheral counter and reference electrodes. This assembly yields a portable and disposable electrochemical platform, effortlessly immobilising DESs onto a porous and economical supporting material like paper. Moreover, the entire configuration resulted in a sensitive, rapidly responsive, membrane-free gas sensor whose response time depended exclusively on the enzymatic reaction. The electroanalytical capabilities of this setup were evaluated through voltammetric and amperometric determinations of phenols in synthetic and real wine samples. The proposed gas enzymatic sensor demonstrated excellent analytical performance for detecting phenolic compounds, offering fast measurement times, simple operation, high sensitivity, wide linear range and good repeatability.