Furthermore, after acidification for 3 h, about 50% T2
intensity decrease was observed. The losses in T2-weighted
intensity are probably attributable to the partial aggregation
of hydrophobic SPIONPs, because the highly stable SPIONP
clusters can efficiently change the spin–spin relaxation time of
the adjacent water protons.10
In summary, we have successfully prepared
a novel
pH-degradable copolymer which can act as a carrier for the
encapsulation of hydrophobic superparamagnetic nano-
particles. The core–shell nanoparticles show favorable bio-
compatibility and chemical stability. The hydrophobic drugs
can also be encapsulated successfully through hydrophobic
interaction. Furthermore, the obtained PDH-coated SPIONPs
can selectively image and release guest drugs in a tumor by
their degradation and aggregation under slightly acidic
conditions. It is believed that additional potential applications
may be possible owing to the material’s aforementioned
outstanding capability.
This work is supported by the National Natural Science
Foundation of China (20876101, 20902065), the Natural
Science Foundation of Jiangsu Province (BK2008158), the
Supporting Project of Jiangsu Province (Industry)
(BE2008061) and Research Fund from Soochow University
(Q3122845).
Fig.
3 T2-weighted MR images of the aqueous dispersion of
PDH-coated SPIONPs at various Fe concentrations (a), and time-
course of mean T2-weighted intensity of PDH-coated SPIONPs in
solutions of different pH (b).
With continued hydrolyzation in an acidic environment, the
nanoparticle aggregates settled at the bottom of the vial. The
process is probably attributed to the agglomeration of the
Notes and references
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c
6710 Chem. Commun., 2010, 46, 6708–6710
This journal is The Royal Society of Chemistry 2010