Biomedical Engineering Reference
In-Depth Information
to assess the treatment efficacy. Theranostics offers the possibility of allowing
imaging to be performed before, after, and during a treatment regimen. The
NMs that are already used as imaging agents can be readily adopted to the
theranostic agents category by loading therapeutic agents and/or functions on
them. The driving force behind this combination is that imaging and therapy
both require sufficient accumulation of agents in diseased tissues. Combining
both the targeting and therapeutic requirement brings the two research areas
closer and since many techniques to enhance imaging can theoretically be read-
ily transferred to the therapeutic domain, and vice versa.
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One of the most versatile and medically useful NMs is the IOMNP because
of all the properties that have been previously mentioned. As such, along with
its ease of synthesis and use, it has been well characterized and studied for ther-
anostic applications. The group of Namiki
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used polymer- and lipid-coated
magnetic nanocrystals, LipoMag, to deliver silencing RNA that was magnet-
ically guided to deliver and silence genes in cells and tumors in mice. This
LipoMag was made of an oleic acid-coated magnetic NM core with a cationic
lipid shell. The LipoMag displayed was used for gene silencing in 9 of 13 cell
lines with improved anti-tumor effects in mice bearing gastric tumors by deliv-
ering a sequence of silencing RNA that targeted the epidermal growth factor
receptor of tumor vessels without adverse immune reaction or side effects.
The theranostic capability of properly designed and engineered NMs has
been captured in the study of perfluorocarbonated materials to target various
atherosclerotic plaque lesion components including the ανβ3 integrin
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and
fibrin.
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In their studies, they applied gadolinium containing lipids on a per-
fluorocarbon core that uses both
19
F and conventional MRI.
3
In the animal stud-
ies where they administered ανβ3 targeted NMs containing the drug fumagillin,
the theranostic showed significant accumulation at the atherosclerotic lesions
during the first week but which was not observed on the second round of ther-
anostic injection in the second week.
This is a good example of NMs applications for a combination of detection,
targeted therapy, and therapy assessment all with a single nanoparticle agent.
A list of theranostic NPs that are currently being studied include siRNA molecu-
lar beacons,
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polymer coated IOMNPs,
295
and those found in a review by Xie.
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7.9 CONCLUSIONS
Pharmacology has definitely been revolutionized by the coming of the nano-
technology era that has seen a boost at the end of the twentieth century and
toward the beginning of the twentyfirst century. NMs have been and research
and development continue to engineer various types of NMs to diagnose disease
and health conditions; to recognize pathogenic infections; to locate, attach, and
penetrate target tissue or structures or pathogens; and dispense the payload of
drugs or biological compound to the targeted regions of the body. This is the
area now known as nanopharmacology.
