Biomedical Engineering Reference
In-Depth Information
dyes or the use of bulky and expensive optical detection systems. As a result, these
sensors are inexpensive to manufacture and portable. It may even be possible to
develop implantable detection and monitoring devices based on these detectors.
Use of Magnetic Nanoparticles as MRI Contrast
Agents for Cardiac Disorders
Magnetic nanoparticles have been used as contrast agent for MRI and have refined
molecular imaging. Targeted imaging of vascular inflammation or thrombosis may
enable improved risk assessment of atherosclerosis by detecting plaques at high risk of
acute complications (Saraste et al.
2009
). Cell death in the heart can be imaged in vivo
by using annexin-labeled magnetic nanoparticles, particularly AnxCLIO-Cy5.5 (Chen
et al.
2011
). Experimental studies have shown the feasibility of combination of diagno-
sis and therapy using magnetic nanoparticles. Magnetic nanoparticles, conjugated with
plasmid DNA expressing enhanced green fluorescent protein and coated with chitosan,
were injected into mice through the tail vein and directed to the heart by means of an
external magnet without the need to functionalize the nanoparticles, and their location
was confirmed by fluorescent imaging (Kumar et al.
2010
). This approach requires
further investigations before clinical applications can be considered.
Use of Perfluorocarbon Nanoparticles
in Cardiovascular Disorders
Perfluorocarbon (PFC) nanoparticles provide an opportunity for combining molec-
ular imaging and local drug delivery in cardiovascular disorders. Ligands such as
MAbs and peptides can be cross-linked to the outer surface of PFCs to enable active
targeting to biomarkers expressed within the vasculature. PFC nanoparticles are
naturally constrained by size to the circulation, which minimizes unintended bind-
ing to extravascular, nontarget tissues expressing similar epitopes. Moreover, their
prolonged circulatory half-life of approximately 5 h allows saturation of receptors
without addition of PEG or lipid surfactant polymerization. The utility of targeted
PFC nanoparticles has been demonstrated for a variety of applications in animal
models and phantoms, including the diagnosis of ruptured plaque, the quantifica-
tion, and antiangiogenic treatment of atherosclerotic plaque and the localization
and delivery of antirestenotic therapy following angioplasty (Lanza et al.
2006
).
Cardiac Monitoring in Sleep Apnea
Because sleep apnea is a cause of irregular heartbeat, hypertension, heart attack,
and stroke, it is important that patients be diagnosed and treated before these highly
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