Biomedical Engineering Reference
In-Depth Information
Figure 1.2
SEM images of as-prepared porous nanosheet-based ZnO microspheres
with low (let ) and high magnii cation (right). (Reprinted with permission from [19];
Copyright © 2008 Elsevier).
metalloenzymes. h e prepared mediator-free third-generation biosensor
displayed good sensitivity and reproducibility for the detection of H
2
O
2
and
NaNO
2
, with wide linear ranges (1-410 and 10-2700 μM, respectively), low
LODs, fast responses and good long-term stability. h e entrapped hemo-
globin exhibited high peroxidase-like activity for the catalytic reduction of
H
2
O
2
with a K
M
app
of 143 μM. h e nanosheet-based ZnO was described as
a promising matrix for the fabrication of direct electrochemical biosensors
applicable in biomedical detection and environmental analysis.
An amperometric H
2
O
2
biosensor based on l owerlike ZnO-gold
nanoparticles (GNPs)-Nai on nanocomposite has been developed [43].
h e l owerlike ZnO-GNPs showed a synergistic ef ect, while the ZnO-
GNPs-Nai on-HRP modii ed GCE promoted the direct electron transfer
of HRP immobilized in the i lm ef ectively, giving an enhanced electro-
catalytic activity towards the reduction H
2
O
2
. h e calculated K
M
app
was 1.76
mM, which is much lower than that reported previously, indicating a high
catalytic activity of HRP. h e catalysis currents increased linearly with the
H
2
O
2
concentration in a wide range from 1.5×10
−5
to 1.1×10
−3
M, and a
LOD of 9.0×10
−6
M was obtained, demonstrating that the formed i lm pro-
vided a favorable microenvironment for the enzyme to retain its activity.
Moreover, the modii ed electrode displayed a rapid response to H
2
O
2
and
possessed good stability and reproducibility.
An amperometric biosensor for H
2
O
2
based on layer-by-layer immo-
bilized HRP on ZnONRs was developed by Gu
et al.
[44]. h e ZnONRs
were fabricated on a gold wire end coated by a thin layer of Zn-Au alloy
to improve the nucleation for growth of ZnO nanostructures and the
