Biomedical Engineering Reference
In-Depth Information
CHAPTER 6
Superoxide electrochemical sensors and
biosensors: principles, development
and applications
Lanqun Mao, Yang Tian, and Takeo Ohsaka
6.1 Chemistry and biochemistry of superoxide
6.2 O
2
bioassay: an overview
6.3 O
2
•
electrochemistry and O
2
•
electrochemical sensors
6.4 Electrochemical sensors for O
2
•
6.4.1 Biosensors with enzymes other than SODs
6.4.2 Brief introduction to SODs
6.4.3 Electrochemistry of SODs
6.4.4 SOD-based electrochemical biosensors for O
2
6.4.5 SOD-based micro-sized biosensors for O
2
•
6.5 Concluding remarks and other directions
6.6 Acknowledgments
6.7 References
6.1 CHEMISTRY AND BIOCHEMISTRY OF SUPEROXIDE
Basically, the complete reduction of one molecule of dioxygen to water essentially
requires four electrons and the intermediates in this reduction process mainly include
superoxide radical (O
2
•
), hydrogen peroxide (H
2
O
2
), and hydroxyl radical (
•
OH)
[1, 2], of which H
2
O
2
is the most stable and the only species that could accumulate
appreciably in neutral aqueous media. It has long been recognized as one of the prod-
ucts of the biological reduction of dioxygen and as a possible explanation for the toxic-
ity of dioxygen [3, 4]. In contrast, the radical intermediates of the reduction of dioxygen
including O
2
•
and
•
OH have fl eeting lifetimes under ordinary conditions and thus have
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