Biomedical Engineering Reference
In-Depth Information
The concentration of the anti-Ab-HRP is directly proportional to the concentra-
tion of the proteins captured by the Ab-IOMNPs. This protocol is written as
a general procedure. All the parameters of the assay need to be optimized to
establish an IOMNP-based assay with selectivity based on the antibody attached
to the IOMNPs. The sensitivity of the assay has to be established using the opti-
mized parameters that includes the optimum (a) concentration of the IOMNP,
(b) concentration of the Ab attached to the IOMNP (or capture Ab), (c) concen-
tration of the HRP-anti-protein, and (d) the incubation times.
Figure 4.7
is a typ-
ical result of an IOMNP-based ELISA that was used to detect the protein HER2
from lysed SK-BR3 cells. The parameters used in this assay were not optimized.
4.10 CONCLUSIONS
Recent advances in nanoscience and nanotechnology have enabled a paradigm
shift in biosensing technology. The use of NPs in diagnostics promises enhanced
sensitivity, shorter turnaround time, and possibly cost-effectiveness. This means
that NP-based assays may even come to surpass current reigning techniques such
as PCR and ELISA. Despite the fact that there are pending regulatory, safety,
and intellectual property issues, and the technologies themselves still need fur-
ther optimization, NPs are primed to transform the field of clinical diagnostics.
When NMs are used as components of biosensors, their unique physico-
chemical properties open up new possibilities for the improvement of the sens-
ing performance. The new area of nanobiosensors involves interaction among
material sciences, engineering, physics, chemistry, and biology at the nanoscale.
Because the unique physicochemical properties of NM, the field of nanobiosen-
sors is quite promising especially in areas that could not be accomplished by
conventional bulk materials.
Inorganic semiconductor QDs have emerged as novel fluorescent labels in
biosensing and imaging, and are substituting the conventional organic fluo-
rophores. This is ascribed to great advantages of inorganic nanocrystals over
the conventional organic dyes. Semiconducting QDs exhibit broad excitation
profiles, narrow and symmetric emission spectra, high photostability and high
quantum efficiency and excellent multiplexed detection capability.
96,173
For
example, QDs with different emission wavelengths can be excited by single
excitation source while organic dyes with different emission wavelengths must
be excited by multiple excitation sources. Demand of simultaneous detection of
more targets in single assay drives the development of inorganic nanocrystal-
based fluorescent probes to replace organic fluorophores.
23,174-177
It is worth noting that, different from the traditional separation between trans-
ducers and molecular recognition probes, a novel tactic is to integrate transduc-
ers with molecular recognition probes to form nanotransducers that recognize
the binding events and actively transduce sensing signals simultaneously.
178
Most of past research on the nanostructured biosensors was the proof-of-
concept work that demonstrated the advantages of NMs and nanostructures. In the
