Enhancement of Superconducting <i>T</i>_c (33 K) by Entrapment of FeSe in Carbon Coated Au–Pd₁₇Se₁₅ 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-Pd₁₆Se₁₅–Au nanoparticle and sharing an interface with Pd₁₇Se₁₅. This assembly exhibits a significant enhancement in the superconducting <i>T</i>_<i>c</i> (onset at 33 K) accompanied by a noticeable lattice compression of FeSe along the ⟨001⟩ and ⟨101⟩ directions. The <i>T</i>_<i>c</i> in FeSe is very sensitive to application of pressure and it has been shown that with increasing external pressure <i>T</i>_<i>c</i> can be increased almost 4-fold. In these composite nanoparticles reported here, immobilization of FeSe on the Pd₁₇Se₁₅ surface contributes to increasing the effect of interfacial pressure, thereby enhancing the <i>T</i>_<i>c</i>. 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>_<i>c</i>. 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

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 poly­(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