Biomedical Engineering Reference
In-Depth Information
samples. A growing number of new diagnostic platforms involving dimen-
sions in the nanometer scale, the nanobiosensors,
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are
rapidly surfacing in the literature to detect and measure biomolecules and
cells with high sensitivity. A homogeneous nanobiosensor occurs in solu-
tion and does not have a phase separation. Chapter 4 is focused mainly on
heterogeneous nanobiosensor which involve a solid platform that serves to
anchor the analyte being detected. The solid capture platform can in itself
be the nanomaterial as in the case of IOMNPs which can be easily sepa-
rated through strong magnets.
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In most cases, the NMs are used not to
capture but to generate the signals because these allow for improved sensitivi-
ties.
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Nanobiosensors are easier to use, faster, and more inexpensive in compari-
son with conventional diagnostics methods. In addition, inexpensive instru-
mentation that accompanies these NM based biosensors is also currently being
developed and is the focus of Chapter 4. The small dimensions of NMs allow
their assembly into barcodes and high-density arrays to detect multiple analytes
using miniature hand held sensing devices that may only need light emitting
diodes as power source.
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Recent advances in nanoscience and nanotechnology have led to various
shifts in biosensing technology. Biosensors find applications not only in the
environment and industries; it also has a wide arena of applications in disease
monitoring and diagnostics. The use of nanoparticles in diagnostics promises
enhanced sensitivity, shorter turn-around-time, and possibly cost-effectiveness.
Thus, NMs based diagnostics schemes may surpass current gold standard tech-
niques such as PCR and ELISA. Despite the fact that there are pending regula-
tory, safety, and intellectual property issues, and the technologies themselves
still need further optimization, nanoparticles are primed to transform the field
of clinical diagnostics.
The application of NMs for medical biosensors makes use of their unique
physicochemical properties for the improvement of the sensing performance.
Nanobiosensor is not a field of its own but is a combination of various disci-
plines such as material sciences, physics, chemistry, biochemistry, engineer-
ing, and biology at the nanoscale. The sensitivity, accuracy, reproducibility and
reliability of nanobiosensors that are attributed to the unique physicochemical
properties of NMs holds promise in monitoring diseases that are difficult to
diagnose except in the later stages of the disease where treatment is close to
being impossible.
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In the area of nanobiosensors especially in imaging sensors and diagnosis,
inorganic semiconductor QDs have emerged as novel fluorescent labels to replace
the conventional organic fluorophores.
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This
is attributed to the properties of QDs which include broad excitation profiles,
narrow and symmetric emission spectra, high photostability and high-quantum
efficiency,
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and multiplexed sensing possibilities.
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QDs with various
sizes that, therefore, have different emission wavelengths can be excited by a
