STRUCTURAL AND MECHANISTIC FEATURES OF CYTOCHROME CD1 NITRITE REDUCTASE

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A quasi-reagentless point-of-care test for nitrite and unaffected by oxygen and cyanide

Publication . Monteiro, Tiago; Gomes, Sara; Jubete, Elena; Añorga, Larraitz; Silveira, Célia M.; Almeida, Maria Gabriela; UCIBIO - Applied Molecular Biosciences Unit; DCV - Departamento de Ciências da Vida; Molecular, Structural and Cellular Microbiology (MOSTMICRO); Instituto de Tecnologia Química e Biológica António Xavier (ITQB); Nature Publishing Group

The ubiquitous nitrite is a major analyte in the management of human health and environmental risks. The current analytical methods are complex techniques that do not fulfil the need for simple, robust and low-cost tools for on-site monitoring. Electrochemical reductase-based biosensors are presented as a powerful alternative, due to their good analytical performance and miniaturization potential. However, their real-world application is limited by the need of anoxic working conditions, and the standard oxygen removal strategies are incompatible with point-of-care measurements. Instead, a bienzymatic oxygen scavenger system comprising glucose oxidase and catalase can be used to promote anoxic conditions in aired environments. Herein, carbon screen-printed electrodes were modified with cytochrome c nitrite reductase together with glucose oxidase and catalase, so that nitrite cathodic detection could be performed by cyclic voltammetry under ambient air. The resulting biosensor displayed good linear response to the analyte (2–200 µM, sensitivity of 326 ± 5 mA M −1 cm −2 at −0.8 V; 0.8–150 µM, sensitivity of 511 ± 11 mA M −1 cm −2 at −0.5 V), while being free from oxygen interference and stable up to 1 month. Furthermore, the biosensor’s catalytic response was unaffected by the presence of cyanide, a well-known inhibitor of heme-enzymes.

2019-12-01Artigo científico

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SFRH/BPD/79566/2011