Biomedical Engineering Reference
In-Depth Information
suitable for human blood serum. By applying a Nai on membrane on the
sensor, its durability increased considerably and the linear range could be
extended to 1,000 μM at the expense of an increased response time from
6.25 s to less than 9 s. h e sensor response was unaf ected by normal con-
centrations of common interferences such as ascorbic acid, glucose, and
urea. Since the sensor was low cost with appreciable reproducibility, it may
of er an easy extension to on-spot clinical diagnosis. It was also considered
as convenient to assemble into portable chip-based sensing devices suit-
able for unskilled users.
Same authors also developed other highly sensitive and stable poten-
tiometric uric acid sensors based on highly-oriented single-crystal hex-
agonal ZnONTs fabricated on the surface of gold coated glass substrate in
an aqueous solution [40]. h e prepared ZnONTs arrays were further used
as a working electrode to fabricate an enzyme-based uric acid biosensor
through immobilizing uricase enzyme by physical adsorption method in
conjunction with a Nai on membrane (Figure 1.8). h e electrochemical
response of the developed sensor is found to be linear over a relatively wide
logarithmic concentration range from 500 nM to 1,500 μM, with a sensi-
tivity of ~68 mV decade
-1
, a LOD of 500 nM, a fast response time ( 7 s),
good selectivity, reproducibility, good anti-interference performance to
pH
meter
Uricase
C
5
H
4
N
4
O
3
(Uric acid) + O
2
+ 2H
2
O
C
6
H
6
N
4
O
3
(Allantoin) + CO
2
+ H
2
O
Uric asid solution
Figure 1.8
Schematic diagram of the uric acid sensing setup using ZnO enzyme as
working electrode and Ag/AgCl as reference electrode, with possible electrochemical
reaction near the working electrode. (Reprinted with permission from [40]; Copyright ©
2011 Simplex Academic Publishers).
