Biomedical Engineering Reference
In-Depth Information
conductive AuNPs. Constructed biosensor showed linear response to glucose
concentration ranged from 20 mM to 0.80 mM (with a detection limit of 17 mM)
and has been successfully applied to detect the glucose level in glucose injections.
Glucose sensor used for blood serum based on eggshell membrane and AuNPs
(Zheng et al.
2011
) is mentioned in medicinal applications in medical section
(
Sect. 3.3
).
Even though it pertains to semi-metals, we will also mention a study dealing
with synthesis of semiconductor selenium NPs employing cells of bacteria
Bacillus
subtilis
. Two kinds (spherical, 1D-trigonal) of Se nanomaterial crystals with good
adhesive ability and biocompatibility were employed as enhancing materials for
hydrogen peroxide (H
2
O
2
) horseradish peroxidase biosensor, with the detection
limit 8 × 10
−8
M (for H
2
O
2
concentration). Different types of Se crystals had no
significant difference in sensor usage. Due to the obtained results, selenium nano-
materials GCE can be a promising instrument for applications dealing with the
detection of H
2
O
2
in food, pharmaceutical, clinical, industrial and environmental
analyses (Wang et al.
2010
).
3.5.2
Electrochemical Applications and Properties
Du et al. (
2007
) demonstrated in communication the bioreduction of aqueous
Au(III) ions by the
E. coli
DH5a bacterial strain. AuNPs bound to the surface of
the bacteria were used for application in direct electron transfer of protein hemo-
globin (glass carbon electrode (GCE) coated by protein layer as well as the AuNPs
biocomposite). Cyclic voltametry experiments were reported for different elec-
trodes at scan rates of 0.1 V/s in pH 7.0 phosphate buffer solution. Although there
are no obvious redox peaks at the blank electrodes (GCE,
E. coli
-GCE, hemoglo-
bin-
E. coli
-GCE and AuNPs-
E. coli
-GCE), a pair of redox peaks (with formal
potential of −0.325 V vs. Ag/AgCl reference electrode) was observed at AuNPs-
hemoglobin-
E. coli
-GCE. These results proved the electron transfer between hemo-
globin and GCE provided by means of the AuNPs modified electrode.
Similarly, extracellular synthesis of AuNPs using plant
Scutellaria barbata
as
the reducing agent was observed (Wang et al.
2009
). The obtained AuNPs were
modified on the GCE and enhanced the electronic transmission rate between the
electrode and the 4-NP.
Remarkably, biosynthesized CdSNPs were also used for construction of an
ideal diode (Kowshik et al.
2002
). Semiconducting NPs were biofabricated by
Schizosaccharomyces pombe
and were confirmed to have a Wurtzite (Cd
16
S
20
)-
type structure. Diode was fabricated by means of tin-doped indium oxide coated
glass substrate. This structure was spin coated by thin film of poly-phenylene
vinylene (p-type material) and with washed
S. pombe
CdSNPs (n-type material)
respectively. Silver contacts were also added. Obtained diode operated at low volt-
age and had forward current value, which makes the structure suitable for use as
an ideal diode.
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