SOD-based electrochemical biosensors for

SCHEME 2 Schematic illustration of analytical mechanism of (a) first-, (b) second-, and (c) third-generation 02 biosensors. Note that the reactions shown in (b) and (c) are bi-directional since SODs are enzymes specifically catalyzing the O2 dismutation, i.e. oxidation into O2 and reduction into H2O2. 

Electrochemical Sensors, Biosensors and Their Biomedical Applications 

On the basis of the direct electron transfer properties of SODs at the SAM-modifled Au electrodes as described in the previous section, Ohsaka et al. have developed SOD-based third-generation 02 biosensors by immobilizing SODs 

Homogeneous Catalytic O2 Disproportionation Heterogeneous Catalytic O2 Disproportionation 

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To fulfill both the requirement of CFME for the practical applications and the necessity of Au substrate to assemble so-called promoters to construct the third-generation biosensor, Tian el al. have combined the electrochemical deposition of Au nanoparticles (Au-NPs) onto carbon fiber microelectrodes with the self-assembly of a monolayer on these Au-NPs to facilitate the direct electron transfer of SOD at the carbon fiber microelectrode. The strategy enabled a third-generation amperometric 02 biosensor to be readily fabricated on the carbon fiber microelectrode. This CFME-based biosensor is envisaged to have great potential for (he detection of 02" in biological systems [158],... 

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