Dissolved oxygen amperometric sensor based on layer-by-layer assembly using host-guest supramolecular interactions |
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Authors: | Flavio S. Damos Rita C.S. Luz Auro A. Tanaka Lauro T. Kubota |
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Affiliation: | a Institute of Chemistry, UNICAMP, P.O. Box 6154, 13084-971 Campinas, SP, Brazil b Department of Chemistry, UFVJM, 39100-000 Diamantina, MG, Brazil c Department of Chemistry, UFMA, 65085-040 São Luis, MA, Brazil d Instituto Nacional de Ciência e Tecnologia de Bioanalítica, UNICAMP, P.O. Box 6154, 13084-971 Campinas, SP, Brazil |
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Abstract: | The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using the host-guest binding of a supramolecular complex at a host surface by combining a self-assembled monolayer (SAM) of mono-(6-deoxy-6-mercapto)-β-cyclodextrin (βCDSH), iron (III) tetra-(N-methyl-4-pyridyl)-porphyrin (FeTMPyP) and cyclodextrin-functionalized gold nanoparticles (CDAuNP). The supramolecular modified electrode showed excellent catalytic activity for oxygen reduction. The reduction potential of oxygen was shifted about 200 mV toward less negative values with this modified electrode, presenting a peak current much higher than those observed on a bare gold electrode. Cyclic voltammetry and rotating disk electrode (RDE) experiments indicated that the oxygen reduction reaction involves probably 4-electrons with a rate constant (kobs) of 7 × 104 mol−1 L s−1. A linear response range from 0.2 up to 6.5 mg L−1, with a sensitivity of 5.5 μA L mg−1 (or 77.5 μA cm−2 L mg−1) and a detection limit of 0.02 mg L−1 was obtained with this sensor. The repeatability of the proposed sensor, evaluated in terms of relative standard deviation was 3.0% for 10 measurements of a solution of 6.5 mg L−1 oxygen. |
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Keywords: | Oxygen Electrocatalysis Layer-by-layer assembly Host-guest interface Supramolecular interaction Amperometric sensor |
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