1 research outputs found
Stable Dispersions of Covalently Tethered Polymer Improved Graphene Oxide Nanoconjugates as an Effective Vector for siRNA Delivery
Conjugates of polyÂ(amidoamine)
(PAMAM) with modified graphene oxide (GO) are attractive nonviral
vectors for gene-based cancer therapeutics. GO protects siRNA from
enzymatic cleavage and showed reasonable transfection efficiency along
with simultaneous benefits of low cost and large scale production.
PAMAM is highly effective in siRNA delivery but suffers from high
toxicity with poor in vivo efficacy. Co-reaction of GO and PAMAM led
to aggregation and more importantly, have detrimental effect on stability
of dispersion at physiological pH preventing their exploration at
clinical level. In the current work, we have designed, synthesized,
characterized and explored a new type of hybrid vector (GPD), using
GO synthesized via improved method which was covalently tethered with
polyÂ(ethylene glycol) (PEG) and PAMAM. The existence of covalent linkage,
relative structural changes and properties of GPD is well supported
by Fourier transform infrared (FTIR), UV–visible (UV–vis),
Raman, X-ray photoelectron (XPS), elemental analysis, powder X-ray
diffraction (XRD), thermogravimetry analysis (TGA), dynamic light
scattering (DLS), and zeta potential. Scanning electron microscopy
(SEM), and transmission electron microscopy (TEM) of GPD showed longitudinally
aligned columnar self-assembled ∼10 nm thick polymeric nanoarchitectures
onto the GO surface accounting to an average size reduction to ∼20
nm. GPD revealed an outstanding stability in both phosphate buffer
saline (PBS) and serum containing cell medium. The binding efficiency
of EPAC1 siRNA to GPD was supported by gel retardation assay, DLS,
zeta potential and photoluminescence (PL) studies. A lower cytotoxicity
with enhanced cellular uptake and homogeneous intracellular distribution
of GPD/siRNA complex is confirmed by imaging studies. GPD exhibited
a higher transfection efficiency with remarkable inhibition of cell
migration and lower invasion than PAMAM and Lipofectamine 2000 suggesting
its role in prevention of breast cancer progression and metastasis.
A significant reduction in the expression of the specific protein
against which siRNA was delivered is revealed by Western blot assay.
Furthermore, a pH-triggered release of siRNA from the GPD/siRNA complex
was studied to provide a mechanistic insight toward unloading of siRNA
from the vector. Current strategy is a way forward for designing effective
therapeutic vectors for gene-based antitumor therapy