6 research outputs found
Elucidating the RNA Nano–Bio Interface: Mechanisms of Anticancer Poly I:C RNA and Zinc Oxide Nanoparticle Interaction
Understanding
the RNA nano–bio interface is critical to
advance RNA based therapeutics. A relevant RNA polyinosinic:cytidilic
acid (poly I:C) is perhaps the best studied in clinical trials and
is now considered an antimetastatic RNA targeting agent. Also, zinc
oxide nanoparticle (ZnO NP) has well-known anticancer activity. In
this work, we explore the RNA nano–bio interface of poly I:C,
its mononucleotides and homopolymers with ZnO NP by UV, fluorescence
and fourier transform infrared (FTIR) spectroscopies. The loading
method and ionic concentration (1.0 M Na<sup>+</sup>) were optimized
for greater physical association of RNA with the NP, providing greater
payload (150 μg/mg NP). The physical parameters of RNA nano–bio
interaction, denoting the degree of association, were quantified by
modified Stern–Volmer equations (<i>K</i><sub>b</sub> = 329.6 g<sup>–1</sup> L). This interface was further studied
by two-dimensional fluorescence difference spectroscopy (2D-FDS),
where greater interaction was indicated by considerable quenching
of the fluorescent hot-spot. The mononucleotides and homopolymers
of inosine had higher payload, binding constants, and 2D-FDS quenching,
implicating the purine ring in ZnO–pIC interaction because
of its greater electron density. X-ray photoelectron spectroscopy
indicates the presence of RNA on the NP surface. Infrared spectral
studies confirm that pIC interacts directly through inosine with the
positive surface of ZnO via the carboxyl group and aromatic ring and
indirectly via the phosphate group
Effect of Nanoparticle Weight on the Cellular Uptake and Drug Delivery Potential of PLGA Nanoparticles
Biodegradable and biocompatible polymeric nanoparticles
(NPs) stand
out as a key tool for improving drug bioavailability, reducing the
inherent toxicity, and targeting the intended site. Most importantly,
the ease of polymer synthesis and its derivatization to add functional
properties makes them potentially ideal to fulfill the requirements
for intended therapeutic applications. Among many polymers, US FDA-approved
poly(l-lactic-co-glycolic) acid (PLGA) is
a widely used biocompatible and biodegradable co-polymer in drug delivery
and in implantable biomaterials. While many studies have been conducted
using PLGA NPs as a drug delivery system, less attention has been
given to understanding the effect of NP weight on cellular behaviors
such as uptake. Here we discuss the synthesis of PLGA NPs with varying
NP weights and their colloidal and biological properties. Following
nanoprecipitation, we have synthesized PLGA NP sizes ranging from
60 to 100 nm by varying the initial PLGA feed in the system. These
NPs were found to be stable for a prolonged period in colloidal conditions.
We further studied cellular uptake and found that these NPs are cytocompatible;
however, they are differentially uptaken by cancer and immune cells,
which are greatly influenced by NPs’ weight. The drug delivery
potential of these nanoparticles (NPs) was assessed using doxorubicin
(DOX) as a model drug, loaded into the NP core at a concentration
of 7.0 ± 0.5 wt % to study its therapeutic effects. The results
showed that both concentration and treatment time are crucial factors
for exhibiting therapeutic effects, as observed with DOX-NPs exhibiting
a higher potency at lower concentrations. The observations revealed
that DOX-NPs exhibited a higher cellular uptake of DOX compared to
the free-DOX treatment group. This will allow us to reduce the recommended
dose to achieve the desired effect, which otherwise required a large
dose when treated with free DOX. Considering the significance of PLGA-based
nanoparticle drug delivery systems, we anticipate that this study
will contribute to the establishment of design considerations and
guidelines for the therapeutic applications of nanoparticles
Synthesis and Characterization of Biomimetic Hydroxyapatite Nanoconstruct Using Chemical Gradient across Lipid Bilayer
In this study, we synthesized biomimetic
hydroxyapatite nanoconstruct
(nanosized hydroxyapatite, NHAp) using a double emulsion technique
combined with a chemical gradient across a lipid bilayer for surface
modification of a titanium (Ti) implant. The synthesized NHAp was
characterized by dynamic light scattering, X-ray diffraction, transmission
electron microscopy, and Fourier transform infrared (FTIR) spectroscopy,
and it was further tested for its biocompatibility and in vitro proliferation
efficacy using normal human osteoblasts (NHOst). The results showed
that the synthesized NHAp had a hydrodynamic diameter of ∼200
nm with high aqueous stability. The chemistry of the NHAp was confirmed
by FTIR spectroscopic analysis. Typical FTIR vibrational bands corresponding
to the phosphate group (PO<sub>4</sub><sup>3–</sup>) present
in hydroxyapatite (HAp) were observed at 670, 960, and 1000 cm<sup>–1</sup>. A broad band at 3500 cm<sup>–1</sup> confirmed
the presence of a structural −OH group in the NHAp. Powder
X-ray crystallographic diffraction further confirmed the formation
of NHAp with characteristic reflections in (002), (211), (130), and
(213) planes at respective 2θ degrees. These reflection planes
are similar to those of typical HAp crystallized toward (002) and
(211) crystallographic planes. The mechanism of the formation of NHAp
was studied using the fluorescence resonance energy transfer (FRET)
technique. The FRET study showed the fluorescent recovery of a donor
fluorophore and the mechanism of the insertion of lipids into nanodroplets
obtained from the first water-in-oil (w/o) emulsion during the formation
of the second oil-in-water (o/w) emulsion. With these confirmations,
we further studied NHOst cell proliferation on a Ti surface. When
NHOst were cultured on the Ti surface coated with the NHAp, a distinct
proliferation pattern and cell–cell communication via cytoplasmic
extension on the substrate surface were observed. In contrast, a bare
Ti surface showed diminished cell size with minimal adherence. This
result indicates that our NHAp covered with a phospholipid bilayer
provides a proper environment essential for cell adhesion, which is
especially important for bone implants, and the inclusion of NHAp
on the Ti substrate would be an effective support for long-term sustainability
of implants
Membrane Fusion-Mediated Gold Nanoplating of Red Blood Cell: A Bioengineered CT-Contrast Agent
Red
blood cells (RBCs) are the natural resident of the vascular
lumen, therefore delivery of any agents within the vascular lumen
could benefit by unique natural transporting features of RBCs. RBCs
continuously circulate for ∼100 days before being sequestered
in the spleen, they only extravasate at sites of vascular hemorrhage.
Taking advantages of these features, we engineered RBC as a carrier
in order to design a unique delivery system capable of delivering
X-ray computed tomography (CT) contrast agents, gold nanoparticles
(AuNPs), thereby acting as CT-contrast agent. A strategic membrane
fusion technique was used to engineer the surface of RBC with gold
nanoparticles in this in vitro study without altering its shape, size,
and surface properties
Synthesis of Multifunctional Magnetic NanoFlakes for Magnetic Resonance Imaging, Hyperthermia, and Targeting.
Iron oxide nanoparticles (IOs) are
intrinsically theranostic agents
that could be used for magnetic resonance imaging (MRI) and local
hyperthermia or tissue thermal ablation. Yet, effective hyperthermia
and high MR contrast have not been demonstrated within the same nanoparticle
configuration. Here, magnetic nanoconstructs are obtained by confining
multiple, ∼ 20 nm nanocubes (NCs) within a deoxy-chitosan core.
The resulting nanoconstructsmagnetic nanoflakes (MNFs)exhibit
a hydrodynamic diameter of 156 ± 3.6 nm, with a polydispersity
index of ∼0.2, and are stable in PBS up to 7 days. Upon exposure
to an alternating magnetic field of 512 kHz and 10 kA m<sup>–1</sup>, MNFs provide a specific absorption rate (SAR) of ∼75 W g<sub>Fe</sub><sup>–1</sup>, which is 4–15 times larger than
that measured for conventional IOs. Moreover, the same nanoconstructs
provide a remarkably high transverse relaxivity of ∼500 (mM
s)<sup>−1</sup>, at 1.41T. MNFs represent a first step toward
the realization of nanoconstructs with superior relaxometric and ablation
properties for more effective theranostics
Soft Discoidal Polymeric Nanoconstructs Resist Macrophage Uptake and Enhance Vascular Targeting in Tumors
Most nanoparticles for biomedical applications originate from the self-assembling of individual constituents through molecular interactions and possess limited geometry control and stability. Here, 1000 × 400 nm discoidal polymeric nanoconstructs (DPNs) are demonstrated by mixing hydrophobic and hydrophilic polymers with lipid chains and curing the resulting paste directly within silicon templates. By changing the paste composition, soft- and rigid-DPNs (s- and r-DPNs) are synthesized exhibiting the same geometry, a moderately negative surface electrostatic charge (−14 mV), and different mechanical stiffness (∼1.3 and 15 kPa, respectively). Upon injection in mice bearing nonorthotopic brain or skin cancers, s-DPNs exhibit ∼24 h circulation half-life and accumulate up to ∼20% of the injected dose per gram tumor, detecting malignant masses as small as ∼0.1% the animal weight <i>via</i> PET imaging. This unprecedented behavior is ascribed to the unique combination of geometry, surface properties, and mechanical stiffness which minimizes s-DPN sequestration by the mononuclear phagocyte system. Our results could boost the interest in using less conventional delivery systems for cancer theranosis