3 research outputs found
Enhancement of Superconducting <i>T</i><sub>c</sub> (33 K) by Entrapment of FeSe in Carbon Coated Au–Pd<sub>17</sub>Se<sub>15</sub> Nanoparticles
FeSe has been an interesting member of the Fe-based superconductor family ever since the discovery of superconductivity in this simple binary chalcogenide. Simplicity of composition and ease of synthesis has made FeSe, in particular, very lucrative as a test system to understand the unconventional nature of superconductivity, especially in low-dimensional models. In this article we report the synthesis of composite nanoparticles containing FeSe nanoislands entrapped within an <i>ent</i>-FeSe-Pd<sub>16</sub>Se<sub>15</sub>–Au nanoparticle and sharing an interface with Pd<sub>17</sub>Se<sub>15</sub>. This assembly exhibits a significant enhancement in the superconducting <i>T</i><sub><i>c</i></sub> (onset at 33 K) accompanied by a noticeable lattice compression of FeSe along the ⟨001⟩ and ⟨101⟩ directions. The <i>T</i><sub><i>c</i></sub> in FeSe is very sensitive to application of pressure and it has been shown that with increasing external pressure <i>T</i><sub><i>c</i></sub> can be increased almost 4-fold. In these composite nanoparticles reported here, immobilization of FeSe on the Pd<sub>17</sub>Se<sub>15</sub> surface contributes to increasing the effect of interfacial pressure, thereby enhancing the <i>T</i><sub><i>c</i></sub>. The effect of interfacial pressure is also manifested in the contraction of the FeSe lattice (up to 3.8% in ⟨001⟩ direction) as observed through extensive high-resolution TEM imaging. The confined FeSe in these nanoparticles occupied a region of approximately 15–25 nm, where lattice compression was uniform over the entire FeSe region, thereby maximizing its effect in enhancing the <i>T</i><sub><i>c</i></sub>. The nanoparticles have been synthesized by a simple catalyst-aided vapor transport reaction at 800 °C where iron acetylacetonate and Se were used as precursors. Morphology and composition of these nanoparticles have been studied in details through extensive electron microscopy
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
mPEG-PAMAM-G4 Nucleic Acid Nanocomplexes: Enhanced Stability, RNase Protection, and Activity of Splice Switching Oligomer and Poly I:C RNA
Dendrimer chemistries have virtually
exploded in recent years with
increasing interest in this class of polymers as gene delivery vehicles.
An effective nucleic acid delivery vehicle must efficiently bind its
cargo and form physically stable complexes. Most importantly, the
nucleic acid must be protected in biological fluids and tissues, as
RNA is extremely susceptible to nuclease degradation. Here, we characterized
the association of nucleic acids with generation 4 PEGylated polyÂ(amidoamine)
dendrimer (mPEG-PAMAM-G4). We investigated the formation, size, and
stability over time of the nanoplexes at various <i>N</i>/<i>P</i> ratios by gel shift and dynamic light scatter
spectroscopy (DLS). Further characterization of the mPEG-PAMAM-G4/nucleic
acid association was provided by atomic force microscopy (AFM) and
by circular dichroism (CD). Importantly, mPEG-PAMAM-G4 complexation
protected RNA from treatment with RNase A, degradation in serum, and
various tissue homogenates. mPEG-PAMAM-G4 complexation also significantly
enhanced the functional delivery of RNA in a novel engineered human
melanoma cell line with splice-switching oligonucleotides (SSOs) targeting
a recombinant luciferase transcript. mPEG-PAMAM-G4 triconjugates formed
between gold nanoparticle (GNP) and particularly manganese oxide (MnO)
nanorods, poly IC, an anticancer RNA, showed enhanced cancer-killing
activity by an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide) cell viability assay