Biomedical Engineering Reference
In-Depth Information
Nanocomposite nanoparticles consisting of polymer-coated g-Fe
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superparamagnetic cores and CdSe/ZnS quantum dots (QDs) shell with the
average diameter of 30 nm were modified with carboxylic groups to increase
their miscibility in aqueous solution. To demonstrate their utility anticycline
E antibodies were immobilized on their surface and then bound to MCF-7
breast cancer cells containing cycline, a protein that is specifically
expressed on the surface of breast cancer cells. The separated breast cancer
cells were easily observed by fluorescence imaging microscopy due to the
strong luminescence of the luminescent/magnetic nanocomposite par-
ticles.
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Other possible applications of magnetic quantum dots can be found
elsewhere.
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10.2.8 Application of Magnetoliposomes
Magnetoliposomes consist of vesicles composed of a phospholipid mem-
brane encapsulating magnetic nanoparticles. These systems have
several important applications, such as in MRI contrast agents, drug
and gene carriers, and cancer-treatment device.
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Different types of mag-
netoliposomes and other magnetic lipidic vesicles have been used as cell
labels.
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Mesenchymal stem cells (MSCs), which can differentiate into multiple
mesodermal tissues, have been magnetically labeled using cationic magne-
toliposomes (leading to the concentration of 20 pg of magnetite per cell), in
order to enrich them magnetically from bone marrow. The magnetolipo-
somes exhibited no toxicity against MSCs in proliferation and differentiation
to osteoblasts and adipocytes. During subsequent culture, a substantially
higher density of cells was obtained, compared to culture prepared without
magnetoliposome treatment.
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Alternatively, another methodology for enriching and proliferating MSCs
from bone marrow aspirates has been developed using antibody-conjugated
magnetoliposomes (AMLs). The AMLs were liposomes conjugated to anti-
CD105 antibody (immunoliposomes) and containing magnetite nano-
particles (10 nm diameter). AMLs successfully labeled MSCs, which could be
separated by magnetic force. The MSCs proliferated and formed colonies.
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Other immunomagnetic systems based on magnetoliposomes bearing spe-
cific antibodies have been used for magnetic labeling of target cells followed
by their positive selection from a cell mixture. Anti-CD34 poly(ethylene gly-
col)-grafted (PEG) immunomagnetoliposomes were prepared and used for
CD34
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cells separation.
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In an in vivo application example, tumor-
specific magnetoliposomes were conjugated with an antibody fragment to
give specificity to target glioma cells. After injection of magnetoliposomes to
mice and exposure to the alternating magnetic field, the temperature of
tumor tissue increased to 43 1C and the growth of the tumor was found to be
arrested over 2 weeks. Magnetoliposomes could target the glioma cells
in vitro and in vivo, and could be eciently applicable to the hyperthermia of
tumors.
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