Biomedical Engineering Reference
In-Depth Information
(a)
0.4
(a)
0.2
0.2 nA
0
10 s
0.2
(b)
(b)
0
50
100
O
2
•
/(nM min
1
)
FIGURE 6.14
(Left panel) Amperometric responses of the Cu, Zn-SOD/Cys/Au/CFME to successive
xanthine injection at applied potentials of (a)
250 mV and (b)
150 mV in O
2
-saturated 0.10 M phosphate
buffer (pH 7.4) containing 0.002 U XOD. (Right panel) Calibration curves for O
2
•
at (a)
250 mV, and
(b)
150 mV. (Reprinted from [158], with permission from Elsevier.)
6.5 CONCLUDING REMARKS AND OTHER DIRECTIONS
Electrochemical biosensors, especially those based on superoxide dismutases, are very
competent for real-time monitoring of O
2
•
production and consumption in biological
systems and would pave a facile, but direct, approach to physiological and pathologi-
cal processes related with ROS and to free radical chemistry. SODs, enzymes specifi c
for O
2
•
dismutation, are considered to be the best choice among all the enzymes
employed for construction of O
2
•
biosensors because of their great catalytic activity
and high specifi city and realizable direct electron transfer properties. These properties
substantially endow the as-prepared SOD-based third-generation O
2
•
biosensors with
excellent analytical properties, such as high sensitivity and selectivity, rapid response
time, and good linearity with nanomolar detection limit. Moreover, the SOD-based
third-generation O
2
•
biosensors could be miniaturized to meet the requirements of
in-vivo
measurements. The excellent properties of the electrochemical O
2
•
biosensors
substantially offer them great potential for real-time monitoring of O
2
•
in biological
tissues, such as brain tissues, which will be the challenge for the future.
6.6 ACKNOWLEDGMENTS
We gratefully acknowledge the fi nancial support from National Natural Science
Foundation of China (Grant Nos 20375043, 20435030, and 20575071 for LM),
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