Biomedical Engineering Reference
In-Depth Information
These chemical sensors hampered the voltammetric responses of
ascorbic acid (AA) and uric acid (UA), while the electrochemical
oxidation of epinephrine was significantly enhanced. Using the
differential pulse voltammetry technique, epinephrine showed a
very well resolved peak centered around 240 mV, while 1 mM of AA
(present in the same solution) was not detected. This optimization
resulted in microsensors with a good linear range (2-100
µ
M)
−1
−2
epinephrine; a good sensitivity (28.1 A M
cm
) and interelectrodes
reproducibility (RSD% = 7.0,
n
= 6), a detection of limit (LOD = 3
s
)
of 2
M; a response time of 6 s; a significant operational stability
(13 h in continuous working conditions) and long term stability (one
month).
µ
. [213] demonstrated aligned CNT thin films
covalently functionalized with a DNA oligonucleotide probe for DNA
electrochemical sensing; detection of the hybridization event with
the target sequence and the electrochemical detection of the duplex
formation was performed by label-free and enzyme-labeled methods.
In case of the enzyme-labeled method a target concentration at
nanomolar level was easily detected with a linear response from
50 to 200 nM, whereas the label-free technique showed a linear
response between 0.5 and 10
Berti
et
al
µ
M. The reproducibility was assessed
good in the range 10-20%.
. [206] reviewed amperometric and potentiometric
biosensors based on the CNTs. In amperometric detections, CNT-
modified electrodes were used as working electrodes to significantly
enhance electroactive surface area. In contrast, the potentiometric
biosensors were based on aptamer-modified CNTFETs. Since
aptamers are artificial oligonucleotides and thus are smaller than
the Debye length, proteins can be detected with high sensitivity. In
this review, the authors discussed on the technology, characteristics,
and developments for commercialization in label-free CNT-based
biosensors.
Maehashi
et al
. [240] demonstrated electrochemical acetylene sensor
based on Au/MWCNTs. Gold nanoparticles (NPs) supported on
MWCNTs were prepared as electrocatalysts for an electrochemical
sensor of acetylene. The electrochemical experiments showed that
the catalysts exhibited a distinctly higher activity for the acetylene
electro-oxidation than Au-NPs and Au/C catalysts. In the typical
cyclic voltammograms, the onset potential of Au/MWCNTs for the
acetylene oxidation is 0.73 V, which is 0.19 V more negative than
Li
et al
