Biomedical Engineering Reference
In-Depth Information
nanoparticles with poly-
- caprolactone [148] These particles were subsequently
used to heat solutions under an AC magnetic fi eld; as the thickness of the polymer
coating increased, the AC susceptibility of the nanomaterials decreased due to the
weaker interparticle magnetic coupling [148] . Takahara
et al.
investigated both
surface- initiated ATRP and nitroxide - mediated radical polymerization ( NMRP ) on
iron oxide nanoparticle surfaces [149]. Here, the surface initiators were bound
through siloxane or phosphate groups to the nanoparticle surfaces, and subse-
quently polymerized with styrene or 3-vinylpyridine [149]. The effi ciencies of the
surface radical initiation processes varied between 10 and 30%, and the resultant
solubilities of the nanoparticle were a direct result of the type of polymer shell [149].
Solution synthesis
of nanoparticles in the presence of polymers is the fi nal route
for preparing core@polymer materials. Gedanken and coworkers have used sono-
chemical methods to produce iron oxide nanoparticles in the presence of polyvinyl
alcohol [150]. These nanoparticles were then functionalized with APTMS, to
produce spherical particles with a fi nal particle diameter of approximately 11 nm
and amine termini [150b]. Following the attachment of anti-PKC
ε
, the particles
were loaded into sperm cells, after which the antibody was shown to remain
active [150b] .
Microgels encapsulating magnetic iron oxide nanoparticles were synthesized by
iron coprecipitation in the presence of a copolymer containing
N
- vinylcaprolactam,
acetoacetoxyethyl methacrylate, and vinylimidizole [151] . The resultant gel - coated
magnetic particles were shown to have smaller hydrodynamic radii than the pure
polymer, this effect being a function of pH (see Figure 14.8). The critical tempera-
ture of these responses was also dependent on the presence of magnetic nanoma-
α
Figure 14.8
The effect of temperature on the
hydrodynamic radii (
R
h
) of iron oxide
nanoparticles coated with
N
- vinylcaprolactam -
co
- acetoacetoxyethyl methacrylate -
co
-
vinylimidizole copolymer hydrogels under
neutral (white) and acidic (black) conditions.
Circles and squares indicate gels with and
without magnetic particles, respectively.
Reproduced with permission from Ref. [151];
© 2007, Wiley-VCH Verlag GmbH & Co.
KGaA.
