Biomedical Engineering Reference
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Figure 10.3
Optical microscopy of magnetic iron oxides microparticles prepared
by microwave assisted synthesis (A); process of magnetic modification
of yeast cells (left tube - S. cerevisiae cells suspension; middle tube -
sedimented iron oxides microparticles for magnetic modification;
right tube - sedimented magnetically modified yeast cells) (B); optical
microscopy of S. cerevisiae cells modified by iron oxides microparticles
(C); magnetic separation of magnetically modified yeast cells (D).
Reproduced, with permission, from Ref. 14.
.
coated with poly(sodium polystyrene sulfonate) (PSS). After repeating the
procedure to build PAH/PSS/PAH coatings on the cells, magnetite nano-
particles were deposited on the cells before the deposition of two additional
polyelectrolyte layers. The final products had the layer structures of PAH/
PSS/PAH/magnetic nanoparticles/PAH/PSS, which preserve the viability of
the yeast cells. Magnetic nanoparticles formed a multilayered coating on the
outer side of the yeast cell walls. Using yeast cells expressing GFP it was
shown that magnetic modification had little effect on the fluorescence
emission.
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In another procedure (poly)allylamine hydrochloride stabilized
positively charged magnetic nanoparticles (average diameter around 15 nm)
were used for the magnetization of living Chlorella pyrenoidosa cells. The
single-step magnetization procedure is very simple and consisted of the
dropwise introduction of the aqueous suspension of algae cells into nano-
particles solution followed by intensive shaking for 10 min. TEM images
demonstrated the uniform layer of magnetic nanoparticles on the cell walls
with the thickness around 90
20 nm,
40
(Figure 10.4).
Magnetic modification of mammalian cells (e.g., stem cells) can be per-
formed using superparamagnetic iron-oxide particles (SPIO). Different iron-
oxide nanoparticles coated by dextran were tested, especially contrast agents
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