Abstract
Animal cells from the Vero lineage and MRC5 human cells were checked for their capacity to catalyse the electrochemical oxygen reduction reaction (ORR). The Vero cells needed 72 hours' incubation to induce ORR catalysis. The cyclic voltammetry curves were clearly modified by the presence of the cells with a shift of ORR of 50 mV towards positive potentials and the appearance of a limiting current (59 μA.cm-2). The MRC5 cells induced considerable ORR catalysis after only 4 h of incubation with a potential shift of 110 mV but with large experimental deviation. A longer incubation time, of 24 h, made the results more reproducible with a potential shift of 90 mV. The presence of carbon nanotubes on the electrode surface or pre-treatment with foetal bovine serum or poly-D-lysine did not change the results. These data are the first demonstrations of the capability of animal and human cells to catalyse electrochemical ORR. The discussion of the possible mechanisms suggests that these pioneering observations could pave the way for electrochemical biosensors able to characterize the protective system of cells against oxidative stress and its sensitivity to external agents.
Highlights
Dissolved oxygen tends to reduce spontaneously on contact with the surface of conductive materials
Many studies have aimed to decipher the mechanisms of oxygen reduction reaction (ORR) microbial catalysis [3]
In 2005, the topic saw a strong revival due to the discovery that ORR microbial catalysis can be exploited to design the cathodes of fuel cells [4,5]
Summary
Dissolved oxygen tends to reduce spontaneously on contact with the surface of conductive materials This spontaneous oxygen reduction reaction (ORR) is very slow at the surface of common carbon-based materials and non-noble metallic materials. Slow, it can still be an effective driver of the corrosion of metallic materials [1]. In 2005, the topic saw a strong revival due to the discovery that ORR microbial catalysis can be exploited to design the cathodes of fuel cells [4,5] In this context, many studies have demonstrated the capacity of various microbial biofilms to catalyse electrochemical ORR in very efficient ways [3,6]. Two different types of microbial ORR catalysis can be distinguished, as detailed below
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