Biomedical Engineering Reference
In-Depth Information
3.5
Electrochemical and Sensing Applications
Metallic NPs are at the centre of intense research because an understanding of their
surface chemistry might play a key role in effective utilization of technologies such
as nanosensor, biosensor, electrocatalysis, nanodevice and nanoelectrochemistry
(Guo and Wang
2007
). From the view of electroanalytical chemistry, more attention
has been paid to AuNPs because of their good biological compatibility, excellent
conducting capability and high surface-to-volume ratio (Daniel and Astruc
2004
).
Usage of AuNPs in electrochemical interfaces has contributed to new vigor in elec-
trochemistry. Development of new techniques and different electrode modified
strategies may potentially enhance analytical selectivity and sensitivity of com-
monly used facilities (Xiong et al.
2007
; Nguyen et al.
2011
).
While not yet containing any direct applications, there are several studies which
are potentially remarkable for their discussion of electrochemical properties.
Biosynthesis of ferroelectric BaTiO3 NPs in assistance of
Lactobacillus sp
. was
reported by Jha and Prasad (
2010
). After modification with PVDF, resulting nano-
composite exhibited enhancement in dielectric properties. AuNPs biosynthesized by
alkalothermophilic actinomycetes
Thermomonospora curvata
,
Thermomonospora
fusca
, and
Thermomonospora chromogena
and stabilized by cross-linker glutaralde-
hyde have potential usage as biosensor enhancer (Torres-Chavolla et al.
2010
)
.
Shilov et al. (
2010
) investigated electro-physical characteristics (cell z-potential,
surface conductivity, electrophoretic mobility, dispersion of cell conductivity) of
yeast cell with silver precipitate.
3.5.1
Sensors
Zheng et al. (
2010b
) reported biosynthesis of Au-Ag alloy NPs by yeast cells and
their application to electrochemical vanillin sensing. Sensitive vanillin sensor based
on glassy carbon electrode (GCE), modified by Au-Ag alloy NPs, was able to
enhance the electrochemical response of vanillin. Electrochemical investigations
confirmed a linear increase of the vanillin oxidation peak current at the sensor with
its concentration in the range of 0.2-50 mM (detection limit 40 nm). Constructed
sensor was successfully applied to the determination of vanillin in samples of
vanilla bean and vanilla tea. This approach suggests possible replacement of com-
monly used methods in vanillin monitoring system (chromatography, capillary
electrophoresis etc.).
Interestingly, Zheng et al. (
2010a
) also published green biosynthesis method for
AuNPs based on usage of natural biomaterial, eggshell membrane (“fresh eggs
were bought from a local supermarket in Hong Kong”). AuNPs on the eggshell
surface were used to immobilize glucose oxidase (by cross-linking method with
glutaraldehyde - Pingarrón et al.
2008
) on the GCE for detection of glucose in solu-
tion. Enzyme activity of glucose oxidase was enhanced by the presence of highly
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