Functional Mesoporous Silica Nanoparticles with a Core-Shell Structure for Controllable Drug Delivery - Advanced Bioactive Inorganic Materials for Bone Regeneration and Drug Delivery - page 70

nSiO 2 @mSiO 2 nanoparticles. These results indicated that magnetic-lumines-
cent mesoporous silica nanoparticles can act as a multifunctional drug car-
rier system, which can target and monitor drugs simultaneously.
3.3.4 Other Multifunctional Mesoporous Silica
Nanoparticles for Controllable Drug Delivery
As mentioned before, mesoporous silica can easily combine with other func-
tional materials to form functional mesoporous silica nanoparticles. Except for
the magnetic and luminescent mesoporous silica nanoparticles, other func-
tional mesoporous silica nanoparticles also have been intensively developed
for drug delivery (Lai et al. 2003; Casasús et al. 2008; Hong et al. 2008; Patel et
al. 2008; Du et al. 2009; Gao et al. 2009; Vivero-Escoto et al. 2009; Bernardos et
al. 2010; Meng et al. 2010; Sun et al. 2010; Xhen, Zheng, et al. 2010; Chen, Chen,
Fang, et al. 2011; Coll et al. 2011; Gan et al. 2011; Xie et al. 2011; Ma et al. 2012).
Xie et al. (2011) synthesized the hexagonal mesoporous silica MCM-41 nano-
spheres with Au nanorods (AuNRs) as core via a modified Stöber method by
a process of hydration and condensation of tetraethoxysilane in a water-etha-
nol mixture. The AuNR@MCM-41 mesoporous silica nanoparticles combine
the photothermal characteristic with the mesopore of MCM-41 in one body
and could realize the light-driven release of drug due to the photothermal
effect of the AuNRs. Therefore, such functional mesoporous silica nanoparti-
cles are favorable for cancer treatment, which combine hyperthermia with the
chemotherapeutic drugs by synergistic effect. Ma et al. (2012) reported a novel
uniform AuNRs-capped magnetic core/mesoporous silica shell nanoellip-
soids (AuNRs-MMSNEs) prepared by coating a uniform layer of AuNRs on
the outer surface of a magnetic core/mesoporous silica shell nanostructure,
based on a two-step chemical self-assembly process (see Figure 3.12) (Ma et
al. 2012). This multifunctional mesoporous silica nanoellipsoids can integrate
simultaneous chemotherapy, photothermotherapy, in vivo MR, infrared ther-
mal, and optical imaging into one single system. Importantly, the multifunc-
tional nanoellipsoids showed high DOX loading capacity and pH-responsive
release, and a synergistic effect of combined chemo- and photothermother-
apy could be obtained at moderate power intensity of NIR irradiation based
on the DOX release and the photothermal effect of AuNRs.
The aforementioned functional core-shell mesoporous silica nanoparticles
are mainly designed with functional cores and mesoporous silica shells.
Actually, a variety of functional core-shell mesoporous silica nanoparticles
with mesoporous silica cores and functional shells have also been developed
for stimuli-responsive controlled drug delivery. That is to say, mesoporous
silica cores serve as containers for drugs and functional shells serve as “gate-
keepers” to trigger drug release only upon exposure to stimuli, which could
decrease side effects to protect the healthy organs from toxic drugs and pre-
vent the decomposition or denaturing of the drugs before reaching the tar-
geted organs or tissues.