Biomedical Engineering Reference
In-Depth Information
Leong et al. reported the fabrication of bifunctional Au/Ni nanorods and their
application for gene delivery. The nanorods, synthesized by electrodeposition into
an Al
2
O
3
template with a pore diameter of 100 nm, were 100 nm in diameter and
200 nm in length with 100 nm gold segments and 100 nm nickel segments. Ni seg-
ment was modified using the 3-[(2-aminoethyl) dithio] propionic acid (AEDP)
linker, through which pDNA was loaded by electrostatic forces. Rhodamine-
conjugated transferrin is selectively bound to the gold segment of the nanorods for
targeting. These multicomponent nanorods could mediate the effective transfection
and expression of the GFP and luciferase reporter genes in human embryonic
kidney (HEK293) mammalian cell line. Nanorods containing compacted plasmids
showed a 4-fold increase in GFP-positive cells in comparison to naked DNA.
Luciferase expression by nanorods transfection was 255 times higher than that
mediated by naked DNA. Bifunctional nanorods conjugated with transferring
increased GFP expression by a factor of 2 (22%) and luciferase expression by a
factor of 3.4, compared with nanorods with compacted plasmids alone. The
in vivo
transfection efficacy of the nanorods was also demonstrated by preliminary studies
in the skin and muscle tissues of mice. Furthermore, the cellular uptake and distri-
bution of nanorods could be visualized by fluorescence and electronic microscopy.
This approach allows the precise control of composition, size and multifunctional-
ity of the gene delivery systems based on nanorods (Salem et al.
2003
).
Studies by Huang et al. suggested that the stability of gold nanorods in biologi-
cally relevant media could be significantly enhanced by layer-by-layer depositing
polyelectrolyte multilayers on their surface. These polyelectrolyte (PE)-gold nano-
rod assemblies (PE-GNRs) possessed a stable Arrhenius-like photothermal
response, which was examined for the hyperthermic therapy of prostate cancer cells
in vitro
. PE-GNRs based on a cationic copolymer of ethyleneglycol diglycidyl ether
and 3,3ยข-diamino-N-methyl dipropylamine showed higher transfection efficacy and
lower cytotoxicity compared to those based on PEI. These results indicate that
judicious engineering of biocompatible polyelectrolytes leads to multifunctional
gold nanorod-based assemblies that combine a variety of simultaneous applications
including optical imaging, nonviral gene delivery, and localized hyperthermia
(Huang et al.
2009
).
6.4
Silica Nanomaterials-Based Multifunctional Vectors
He and Minko have reported the first effort of utilizing mesoporous silica nano-
particles (MSNs) as a multifunctional system to simultaneously deliver doxorubi-
cin (Dox) and Bcl-2-targeted siRNA into multidrug resistant A2780/AD human
ovarian cancer cells for efficient chemotherapy (Chen et al.
2009
). To develop this
nano-platform, MSNs were modified to encapsulate Dox inside the pores to
achieve minimal premature release. Then the Dox-loaded MSNs were decorated
with amine-terminated PAMAM dendrimers (generation 2). The dendrimer-
modified MSNs could efficiently complex with siRNAs targeted against mRNA
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