Biomedical Engineering Reference
In-Depth Information
delivery carrier contributed to the highly efficient target-specific integrated
with the liver tissues with HAp receptors like cluster determinant 44 (CD44)
or hyaluronan receptor for endocytosis (HARE). Cysteamine modified gold
nanoparticles (AuCM)/siRNA/PEI/HAp complex was successfully devel-
oped using a layer-by-layer method showing an excellent target-specific
gene silencing effciency of ca. 70% in the presence of 50 vol% serum (Lee et
al. 2011). High density lipoprotein (HDL) can target cancer cells that overex-
press HDL receptors for dependence upon cholesterol delivery to maintain
membrane biosynthesis and integrity (Ryan 2010).
Also, biomimetic spherical
HDL has been synthesized to mimic the size, shape, and surface chemistry
of natural LDL. To take full advantage of this feature, HDL AuNPs success-
fully conjugated with antisense cholesterylated DNA regulated target gene
expression (McMahon et al. 2011).
To enhance the uptake by anionic charge cell membrane, the conventional
systems that were modified to be a positive surface charge might induce
nonspecific binding with blood serum components resulting in aggregation
and embolism in the body (Park et al. 2010). In contrast, the gold nanoparticles
coated with PEI, PEG, and hyaluronic acid all showed negative zeta potential
and the cell internalized efficiently in spite of the electrostatic repulsion that
occurred between the surface of the cell and the hybrid surface (Kawano et
al. 2006; Cebrián et al. 2011; Lee et al. 2011).
Meanwhile, the methods for fabrication of hybrid vectors were improved
to avoid the complex surface functionalization, heterogeneous mixture, and
potential toxicity. The idea of one-pot synthesized polypeptide-conjugated
AuNPs was brought out by using positively charged polypeptides serv-
ing not only as capping agents but also as reductants subverting the classic
ligand exchange strategy (Yan et al. 2012). Moreover, the instability of gold
nanoparticles after centrifuged to remove cetyltrimethyl ammonium bro-
mide limits its diverse biological applications. A delivery system by deposit-
ing gold nanoparticle surface with alternating layers of anionic and cationic
polyelectrolytes was developed and demonstrated a stable and admirable
photothermal response (Huang et al. 2010).
7.3.3 Silicate-Based Hybrid Material for Gene Delivery
Silicate nanoparticle has been considered a promising material due to the
variety of available chemical and physical modifications. It can be tailored
with a variety of modifiers by customizing the structures and physicochem-
ical properties to achieve suitable particle size, stability, and high-loading
capacity providing an efficient and safety carrier for gene delivery. Roy (2005)
introduced an organically modified silica nanoparticle as DNA carriers, pro-
viding a promising direction for targeted therapy with enhanced efficacy as
well as for real-time monitoring of drug action. Due to positively charged
cationic-amino groups that were surface functionalized, the nanoparticle
bound to DNA efficiently with individual fluorescence cross-linked.
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