Chemically anchored two-dimensional-SiO x /zero-dimensional-MoO2 nanocomposites for high-capacity lithium storage materials.

Silicon oxides are promising alternatives for graphite anodes in lithium-ion batteries. SiO x nanosheets exhibit favorable anodic performances, including outstanding capacity retention and dimensional stability, due to their unique two-dimensional (2D) microstructures, but suffer from low specific capacity and poor initial coulombic efficiency. Here we demonstrate that chemically anchoring of molybdenum dioxide (MoO2) nanoparticles on the surface of 2D-SiO x nanosheets via a Mo-O-Si bond boosts both the reversible capacity and initial coloumbic efficiency without sacrificing the useful properties of 2D-SiO x nanosheets. The enhancements can be attributed to the introduction of a zero-dimensional MoO2 nano-object, which offers abnormal storage sites for lithium. The proposed nano-architecturing shows how we can maximize the advantages of 2D nanomaterials for energy storage applications.

Si Nanocrystal-Embedded SiO x nanofoils: Two-Dimensional Nanotechnology-Enabled High Performance Li Storage Materials.

Silicon (Si) based materials are highly desirable to replace currently used graphite anode for lithium ion batteries. Nevertheless, its usage is still a big challenge due to poor battery performance and scale-up issue. In addition, two-dimensional (2D) architectures, which remain unresolved so far, would give them more interesting and unexpected properties. Herein, we report a facile, cost-effective, and scalable approach to synthesize Si nanocrystals embedded 2D SiO x nanofoils for next-generation lithium ion batteries through a solution-evaporation-induced interfacial sol-gel reaction of hydrogen silsesquioxane (HSiO1.5, HSQ). The unique nature of the thus-prepared centimeter scale 2D nanofoil with a large surface area enables ultrafast Li+ insertion and extraction, with a reversible capacity of more than 650 mAh g-1, even at a high current density of 50 C (50 A g-1). Moreover, the 2D nanostructured Si/SiO x nanofoils show excellent cycling performance up to 200 cycles and maintain their initial dimensional stability. This superior performance stems from the peculiar nanoarchitecture of 2D Si/SiO x nanofoils, which provides short diffusion paths for lithium ions and abundant free space to effectively accommodate the huge volume changes of Si during cycling.

Multivalent Aptamer-RNA Conjugates for Simple and Efficient Delivery of Doxorubicin/siRNA into Multidrug-Resistant Cells.

Multivalent aptamer-siRNA conjugates containing multiple mucin-1 aptamers and BCL2-specific siRNA are synthesized, and doxorubicin, an anthracycline anticancer drug, is loaded into these conjugates through intercalation with nucleic acids. These doxorubicin-incorporated multivalent aptamer-siRNA conjugates are transfected to mucin-1 overexpressing MCF-7 breast cancer cells and their multidrug-resistant cell lines. Doxorubicin-incorporated multivalent aptamer-siRNA conjugates exert promising anticancer effects, such as activation of caspase-3/7 and decrease of cell viability, on multidrug-resistant cancer cells because of their high intracellular uptake efficiency. Thus, this delivery system is an efficient tool for combination oncotherapy with chemotherapeutics and nucleic acid drugs to overcome multidrug resistance.

One-Step Formation of Silicon-Graphene Composites from Silicon Sludge Waste and Graphene Oxide via Aerosol Process for Lithium Ion Batteries.

Over 40% of high-purity silicon (Si) is consumed as sludge waste consisting of Si, silicon carbide (SiC) particles and metal impurities from the fragments of cutting wire mixed in ethylene glycol based cutting fluid during Si wafer slicing in semiconductor fabrication. Recovery of Si from the waste Si sludge has been a great concern because Si particles are promising high-capacity anode materials for Li ion batteries. In this study, we report a novel one-step aerosol process that not only extracts Si particles but also generates Si-graphene (GR) composites from the colloidal mixture of waste Si sludge and graphene oxide (GO) at the same time by ultrasonic atomization-assisted spray pyrolysis. This process supports many advantages such as eco-friendly, low-energy, rapid, and simple method for forming Si-GR composite. The morphology of the as-formed Si-GR composites looked like a crumpled paper ball and the average size of the composites varied from 0.6 to 0.8 µm with variation of the process variables. The electrochemical performance was then conducted with the Si-GR composites for Lithium Ion Batteries (LIBs). The Si-GR composites exhibited very high performance as Li ion battery anodes in terms of capacity, cycling stability, and Coulombic efficiency.

A swelling-suppressed Si/SiOx nanosphere lithium storage material fabricated by graphene envelopment.

A swelling-suppressed, Si nanocrystals-embedded SiOx nanospheres lithium storage material was prepared by graphene envelopment. The free void spaces formed between the graphene envelope and Si/SiOx nanospheres effectively accommodated the volume changes of Si/SiOx nanospheres during cycling, which significantly suppresses the swelling behavior and improves the capacity retention up to 200 cycles.

High-Performance Si/SiOx Nanosphere Anode Material by Multipurpose Interfacial Engineering with Black TiO(2-x).

Silicon oxides (SiOx) have attracted recent attention for their great potential as promising anode materials for lithium ion batteries as a result of their high energy density and excellent cycle performance. Despite these advantages, the commercial use of these materials is still impeded by low initial Coulombic efficiency and high production cost associated with a complicated synthesis process. Here, we demonstrate that Si/SiOx nanosphere anode materials show much improved performance enabled by electroconductive black TiO(2-x) coating in terms of reversible capacity, Coulombic efficiency, and thermal reliability. The resulting anode material exhibits a high reversible capacity of 1200 mAh g(-1) with an excellent cycle performance of up to 100 cycles. The introduction of a TiO(2-x) layer induces further reduction of the Si species in the SiOx matrix phase, thereby increasing the reversible capacity and initial Coulombic efficiency. Besides the improved electrochemical performance, the TiO(2-x) coating layer plays a key role in improving the thermal reliability of the Si/SiOx nanosphere anode material at the same time. We believe that this multipurpose interfacial engineering approach provides another route toward high-performance Si-based anode materials on a commercial scale.

Dual-Size Silicon Nanocrystal-Embedded SiO(x) Nanocomposite as a High-Capacity Lithium Storage Material.

SiOx-based materials attracted a great deal of attention as high-capacity Li(+) storage materials for lithium-ion batteries due to their high reversible capacity and good cycle performance. However, these materials still suffer from low initial Coulombic efficiency as well as high production cost, which are associated with the complicated synthesis process. Here, we propose a dual-size Si nanocrystal-embedded SiOx nanocomposite as a high-capacity Li(+) storage material prepared via cost-effective sol-gel reaction of triethoxysilane with commercially available Si nanoparticles. In the proposed nanocomposite, dual-size Si nanocrystals are incorporated into the amorphous SiOx matrix, providing a high capacity (1914 mAh g(-1)) with a notably improved initial efficiency (73.6%) and stable cycle performance over 100 cycles. The highly robust electrochemical and mechanical properties of the dual-size Si nanocrystal-embedded SiOx nanocomposite presented here are mainly attributed to its peculiar nanoarchitecture. This study represents one of the most promising routes for advancing SiOx-based Li(+) storage materials for practical use.

Long chain microRNA conjugates in calcium phosphate nanoparticles for efficient formulation and delivery.

A long chain microRNA-34a conjugate (lc-miRNA) was prepared by chemical crosslinking in order to improve entrapment efficiency into calcium phosphate nanoparticles (CaPs) and intracellular delivery. Thiol-modified miRNA at both terminal ends was chemically conjugated using crosslinkers to form lc-miRNA which was encapsulated within CaPs by a conventional co-precipitation method. Encapsulation efficiencies, physicochemical properties, and in vitro intracellular delivery efficiencies of the prepared linear polyethyleneimine (LPEI)-coated CaPs (LPEI-CaP) containing common miRNA and lc-miRNA were comparatively evaluated. The prepared lc-miRNA exhibited noticeably enhanced encapsulation efficiency during the CaP formulation process when compared to common miRNA. LPEI-CaP/lc-miRNAs consisted of nano-sized particles with great homogeneity and were observed to be successfully delivered into PC-3 cells. Fabricated LPEI-CaPs with duplex form of lc-miRNA (lc-miRNA-d) suppressed cancer cell proliferation as well as migration much more efficiently than those with duplex form of miRNA (miRNA-d). In addition, LPEI-CaP/lc-miRNA-d conferred negligible cytotoxicity on PC-3 cells. Chemical crosslinking of therapeutic miRNAs via a reducible linkage may allow more efficient encapsulation within CaPs as well as homogeneous particle formulation due to a higher spatial charge density than common miRNAs. The well-formulated LPEI-CaPs with lc-miRNA-d have the potential to provide superior miRNA transfection efficiency and inhibition of cancer proliferation.

Evaluation of multimeric siRNA conjugates for efficient protamine-based delivery into breast cancer cells.

Despite the preferable properties of well-defined cationic peptides for small interfering RNA (siRNA) delivery, their application as siRNA carriers remains limited due to their poor binding affinity with short-chain RNAs. In this study, we investigated the feasibility of a novel strategy for circumventing this limitation, by assessing the utility of multimeric conjugates of siRNA for improving the binding affinity of siRNAs with cationic peptides and the extent of intracellular delivery. Protamine, a natural and arginine-rich peptide, was used to produce stably condensed polyelectrolyte complexes (PECs) with multimeric siRNAs (multi-siRNA) with a size of 120 nm while conventional siRNA/protamine particles are over 500 nm. The formulated multi-siRNA/protamine PECs showed greatly enhanced stability, intracellular uptake, and biocompatibility compared to conventional, monomeric (mono)-siRNA/protamine particles. With the addition of chloroquine, multi-siRNA/protamine PECs successfully inhibited target gene expression in MDA-MB-435 cells, a breast cancer cell line, even in the presence of serum protein. This study demonstrates that multi-siRNA conjugates greatly facilitate the formulation of nano-sized protamine-based carriers and significantly improve intracellular delivery in vitro compared to common siRNAs, and therefore may provide a platform for the design of peptide-based siRNA delivery systems for in vivo applications.

Multivalent comb-type aptamer-siRNA conjugates for efficient and selective intracellular delivery.

In this study, a simple and efficient strategy for selective intracellular delivery of RNA therapeutics into target cancer cells was designed using direct complementary base pairing between chemically conjugated multimeric antisense strands and aptamer-incorporating sense strands.