Biomedical Engineering Reference
In-Depth Information
Jokerst et al. (2009)
further report that the ELISA method, which has been the gold standard
to detect proteins since 1971, requires an analysis time of 254.4 min (4.24 h), but their
QD-based NBC method requires an analysis time of just 27 min. This represents a significant
decrease in the time required, by a factor of 9.4.
Jokerst et al. (2009)
emphasize the importance of LOD in detecting cancer biomarkers in
saliva as compared to serum. This, as indicated earlier, is due to the much lower con-
centrations of these biomarkers in saliva. They report that their QD-based NBC permits a
high signal at relatively low concentrations of their detection limit, which helps minimize
background noise and supports their excellent LOD measurements. On analyzing clinical
samples of saliva and serum for these cancer biomarkers, they state that their proof-of-concept
pilot studies yield strong correlation results when their NBC method is compared with stan-
dard laboratory-based methods. Of special interest is the low LOD values observed, which
should positively affect patient outcomes. Finally,
Jokerst et al. (2009)
report that (a) their
QD-based NBC assay was reproducible, (b) it was able to detect CEA-specific signals in
clinical samples of saliva, and (c) it exhibited multiplexing capabilities by detecting all three
cancer biomarkers, CEA, CA 125, and Her-2/Neu (C-erB-2) after the beads were sensitized
to either of the above mentioned cancer biomarkers. For example, they prove that their
NBC biosensor is able to detect CEA-specific antigen, and is independent of the presence
of 0-400 U/ml CA 125.
They conclude by asserting that their QD-based NBC is an important step towards realizing a
harmonized nano-bio analysis system. Their study is the first in which QDs provide quanti-
tative information with regard to cancer biomarkers from saliva samples. Also,
their
integrated NBC system is disposable, which is an added advantage.
5.4 Carbon Nanofiber Paste Electrode Nonenzymatic Glucose
Sensor (
Liu et al., 2009
)
Liu et al. (2009)
have recently developed a nonenzymatic glucose sensor which consists of a
renewable NiCFP electrode. The authors used an electrospinning technique combined with
thermal treatment to make this electrode. They noted that significant amounts of spherical
nanoparticles were either well dispersed or embedded in the carbon nanofibers. These
nanoparticles were comprised of Ni and NiO. They also noted that their electrospun
electrodes when mixed with mineral oil exhibited a rapid response and were also not poi-
soned by the chloride ions. The authors point out that as the Ni nanoparticles are firmly
embedded and their carbon based electrode is inert, they are highly sensitive and stable
biosensors. Also, the method of fabrication of their biosensor is simple and inexpensive.
Liu et al. (2009)
also mention that ever since
Clark and Lyons (1962)
proposed the enzyme
electrode for glucose determination,
there has been considerable interest for over five
