Flow injection enzymatic biosensor for aldehydes based on a Meldola Blue-Ni complex electrochemical mediator
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ORIGINAL PAPER
Flow injection enzymatic biosensor for aldehydes based on a Meldola Blue-Ni complex electrochemical mediator Ana Maria Titoiu 1 & Georgiana Necula-Petrareanu 2 & Diana Visinescu 3 & Valentina Dinca 4 & Anca Bonciu 4,5 & Cristian N. Mihailescu 4 & Cristina Purcarea 2 & Rabah Boukherroub 6 & Sabine Szunerits 6 & Alina Vasilescu 1 Received: 21 March 2020 / Accepted: 4 August 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Carbon nanofibers (CNF) are efficient electrode modifiers in electrochemical biosensors that enhance the electrochemical active area, induce electrocatalytic effect toward the oxidation of the enzymatic cofactor nicotinamide adenine dinucleotide (reduced form, NADH), and enable the quantitative immobilization of enzymes. Combining CNF with efficient and stable mediators radically augments the speed of electron transfer between NADH and solid electrodes and leads to electrochemical sensors characterized by high sensitivity and stability. The main aim of this work was to investigate the performance of a novel mediator for NADH with advantageously low solubility in an electrochemical detector based on a screen-printed CNF electrode as well as its potential in biosensing. Using a mediator, prepared from Meldola Blue and Ni hexamine chloride, a stable and sensitive electrochemical NADH sensor is provided with a detection limit of 0.5 μmol L−1. Further on, covalent immobilization of a recently described aldehyde dehydrogenase from the Antarctic Flavobacterium PL002 strain on the surface of the mediatormodified electrode produced a stable biosensor for the detection of aldehydes. When integrated in a flow injection analysis (FIA) setup with amperometric detection at 0.1 V vs. Ag/AgCl, the measurement of benzaldehyde with a detection limit of 10 μmol L−1 over a linear range of 30–300 μmol L−1 is possible. Determination of trace benzaldehyde impurities in a pharmaceutical excipient was also demonstrated and results compared with a chromatographic method. Keywords Carbon nanofibers . Electrochemical mediator . NADH . Aldehyde dehydrogenase . Flow injection analysis . Benzaldehyde sensing
Introduction Many important biotransformations in biological systems and industrial processes use the enzymatic cofactor recycling
system between nicotinamide adenine dinucleotide (NAD+) and its reduced form NADH based on the following reaction: Substrate þ N ADþ þ H 2 O
dehydrogenase
→
Product þ N ADH þ H þ ð1Þ
Ana Maria Titoiu and Georgiana Necula-Petrareanu contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04477-3) contains supplementary material, which is available to authorized users. * Alina Vasilescu [email protected]
4
National Institute for Laser, Plasma and Radiation Physics (INFLPR), 409 Atomistilor, 077125 Magurele, Romania
1
International Centre of Biodynamics, 1B Intrarea Portocalelor, 060101 Bucharest, Romania
5
Faculty of Physics, University of Bucharest, 077125 Mag
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