Biomedical Engineering Reference
In-Depth Information
rate in nanomedicine is expected to have a significant impact that can improve
worldwide economy.
Although methods for bioconjugation of NMs have been in existence for
some time, it is apparent that their application to infectious diseases diagnostics
is limited. At present, bioconjugation of NMs are done to make them as probes
for imaging, as delivery vehicles for cancer drugs,
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and as therapeutics for the
removal of tumor cells.
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NMs are currently being studied for drug deliv-
ery to improve the bioavailability of a drug, where they are most needed in the
body over a time frame which will be achieved by molecular targeting using
nano-engineered devices.
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NMs have unusual properties that can be used
to improve drug delivery.
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Attachment of specific probes that guide the
NMs to the specific cell as a specific tissue can save more than $65 billion that is
wasted each year due to poor bioavailability. Drug delivery systems using lipid-
or polymer-based NMs or magnetic NPs (MNPs) can be designed to improve
the pharmacological and therapeutic properties of generally nonpotent and pos-
sibly harmful drugs to nearby healthy cells. Drugs made of proteins and pep-
tides show enormous potential for treatment of various diseases and disorders.
Targeted and/or controlled delivery of these biopharmaceuticals using NMs is a
rapidly growing area of research.
NMs are also actively being developed for in vitro and in vivo imag-
ing.
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MNPs are now being used as contrast agents
giving improved images from ultrasound and MRI. Diagnosis of diseases such
as cancer and infectious diseases at their early stages for effective treatment
may be achieved with brighter, more stable, and more sensitive NMs.
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QDs with quantum confinement properties like size-tunable light emission,
when used in conjunction with MRI can produce exceptional images of tumor
sites. These NPs are much brighter than organic dyes and only need one light
source for excitation. This means that the use of fluorescent QDs could produce
a higher contrast image and at a lower cost than today's organic dyes that are
used as contrast agents. The small size of NPs (10-100 nm) allows them to pref-
erentially accumulate at tumor sites, which lack an effective lymphatic drainage
system.
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Biosensor development is one of the rapidly growing areas of NM appli-
cations in medicine.
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These sensors may be in the
form of lateral flow immunoassay, glass slide-type sensors, or disposable lab on
a chip-type of sensors.
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An approach using a solid phase
involving a sandwich-type assay with an Ab against a specific target and a QD-
labeled Ab allows QD-based detection of the analyte of interest.
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The
large number (5-200) of potential surface attachment groups on QDs allows
possible incorporation of various molecules for sensing.
In one study, Xu and his collaborators
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demonstrated the use of IOMNPs
for the immunomagnetic separation of tumor cells from fresh whole blood. The
process involved 30 nm IOMNPs that are amphiphilic polymer coated. These
were covalent conjugated with Abs against human epithelial growth factor
