Biomedical Engineering Reference
In-Depth Information
(180 mg DOC/g PEG/FA-Fe
3
O
4
@mSiO
2
nanoparticles) and excellent blood
compatibility. Most important, the DOC-loaded Fe
3
O
4
@mSiO
2
nanoparticles
showed the greater cytotoxicity than free DOX to induce MCF-7 cell death
due to the drug release in cells. Therefore, compared with the normal core-
shell magnetic mesoporous silica nanoparticles, rattle-type magnetic meso-
porous silica nanoparticles are more suitable as excellent anticancer drug
carriers for targeting drug release.
Zhu et al. (2009; Zhu, Ikoma, et al. 2010; Zhu, Jian, and Wang 2011) have
also conducted extensive investigations into the preparation of rattle-type
magnetic mesoporous silica nanoparticles with large cavities by using col-
loidal carbon spheres as the templates. As shown in Figure 3.7, the first step
involved the preparation of the colloidal carbon spheres adsorbed with
iron precursor by a one-pot hydrothermal treatment. In the next step, the
organosilicate-incorporated silica shells were deposited on the colloidal
carbon spheres through the simultaneous sol-gel polymerization of TEOS
and C18TMS. Finally, rattle-type Fe
3
O
4
@SiO
2
hollow mesoporous spheres
were obtained after the calcination to remove the carbon templates and the
organic groups of C18TMS, and then the reduction under H
2
/Ar atmosphere
(Zhu, Ikoma, et al. 2010). The particle sizes, mesoporous shell thicknesses,
and Fe
3
O
4
amounts can be readily controlled by adjusting the experimen-
tal conditions. It has been studied that these Fe
3
O
4
@SiO
2
hollow mesopo-
rous spheres had no cytotoxicity against Hela cells and exhibited relatively
fast cell uptake localized near the nucleus. DOX released from Fe
3
O
4
@SiO
2
hollow mesoporous spheres had a sustained release pattern, and the DOX-
loaded spheres exhibited greater cytotoxicity than free DOX (Zhu, Ikoma, et
al. 2010).
Furthermore, these rattle-type Fe
3
O
4
@SiO
2
hollow mesoporous spheres
can be modified with functional ligands or groups for multifunctional
applications (Zhu, Fang, and Kaskel 2010; Zhu, Meng, Gao, et al. 2011; Zhu,
Meng, and Hanagata 2011). Folate-conjugated Fe
3
O
4
@SiO
2
hollow mesopo-
rous spheres have been developed as anticancer drug carriers for the tar-
geted drug delivery system (Zhu, Fang, and Kaskel 2010). It is interesting that
the drug delivery system combines the abilities of receptor-mediated and
magnetic targeting, and the DOX-loaded Fe
3
O
4
@SiO
2
-FA spheres exhibited
greater cytotoxicity than free DOX and DOX-loaded Fe
3
O
4
@SiO
2
spheres due
to the increase of cell uptake of anticancer drug delivery system mediated by
the FA receptor. On the other hand, Zhu, Meng, Gao, et al. (2011) have also
designed and constructed an enzyme-responsive carrier for co-delivery of
drugs and genes using rattle-type Fe
3
O
4
@SiO
2
hollow mesoporous spheres
(HMS)/poly(L-lysine) (PLL) core-shell particles (Figure 3.8). The first step
involves the loading of fluorescein, a model drug, into HMS particles and
the modification with 3-aminopropyltriethoxysilane on the surface of the
fluorescein-loaded particles to obtain the modified fluorescein-loaded HMS
(MFHMS) particles. In the next step, the MFHMS particles are coated by a
layer-by-layer (LbL) assembly with negatively charged CpG ODN, a model
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