Voltammetric Biosensor Based on Silver Nanowires and Tyrosinase for the Electrochemical Detection of Catechol

Abstract

An enzymatic electrochemical biosensor for catechol detection based on silver nanowires (AgNWs), has been developed. The employment of AgNWs was essential to improve the electron transfer in comparison with that offered by an ITO substrate. AgNWs’ electrocatalytic properties and high affinity with biomolecules make them desirable for constructing biosensors. Combining nanomaterials with enzymes reduces insulating effects, due to the high-efficient electrical activity from the active site of the enzyme to the electrode. Moreover, the employment of these proteins increases the specificity of the sensor. Among the variety of processes available to synthesize AgNWs [1,2], polyol process has been selected, because of the simplicity and reliability it offers. The employed method consisted in a silver precursor (AgNO3) reduction in presence of Ethylene glycol as a solvent and polyvynilpyrrolidone, which is a surfactant that facilitates the AgNWs dispersion. The developed biosensor results from the immobilization of tyrosinase (TYR) on the top of the AgNWs deposited by spin coating in a different concentration ratio. FTIR, UV-vis, DRX and AFM have confirmed the proposed structure and cyclic voltammetry has shown the amplification caused by the combination of the nanomaterial and the enzyme in the film denoting their excellent performance, sensitivity and reproducibility. Moreover it has been demonstrated that the concentration of AgNWs employed in the development of the biosensors is crucial in terms of reproducibility, in addition to being excellent electronic mediators. Figure 1. Voltametric response of ITO-Tyr (red) and ITO-AgNWs-TYR (black) onto ITO surface to 10-4M catechol in phosphate buffer 10-2M. [1] Xu, L. et al. Anal. Methods 7, 5649-5653 (2015), [2] Kumar-Krishnan, S. et al. RSC Adv. 6, 20102–20108 (2016) Acknowledgments: Financial support by MINECO and FEDER (RTI2018-097990-B-100 and BES-2016-077825) and the Junta de Castilla y León-FEDER (VA-275P18) is gratefully acknowledged. Figure 1