12 results
Search Results
Now showing 1 - 10 of 12
- ItemFe3O4 Nanoparticles Grown on Cellulose/GO Hydrogels as Advanced Catalytic Materials for the Heterogeneous Fenton-like Reaction(Washington, DC : ACS Publications, 2019) Chen, Yian; Pötschke, Petra; Pionteck, Jürgen; Voit, Brigitte; Qi, HaisongCellulose/graphene oxide (GO)/iron oxide (Fe3O4) composites were prepared by coprecipitating iron salts onto cellulose/GO hydrogels in a basic solution. X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared, and X-ray diffraction characterization showed that Fe3O4 was successfully coated on GO sheets and cellulose. Cellulose/GO/Fe3O4 composites showed excellent catalytic activity by maintaining almost 98% of the removal of acid orange 7 (AO7) and showed stability over 20 consecutive cycles. This performance is attributable to the synergistic effect of Fe3O4 and GO during the heterogeneous Fenton-like reaction. Especially, the cellulose/GO/Fe3O4 composites preserve their activity by keeping the ratio of Fe3+/Fe2+ at 2 even after 20 catalysis cycles, which is supported by XPS analysis.
- ItemRoom temperature single-step synthesis of metal decorated boron-rich nanowires via laser ablation(Heidelberg : Springer Verlag, 2019) Gonzalez-Martinez, I.G.; Bachmatiuk, A.; Gemming, T.; Cuniberti, G.; Trzebicka, B.; Rummeli, M.H.Hybrid nanostructures, such as those with nanoparticles anchored on the surface of nanowires, or decorated nanowires, have a large number of potential and tested applications such as: gas sensing, catalysis, plasmonic waveguides, supercapacitors and more. The downside of these nanostructures is their production. Generally, multi-step synthesis procedures are used, with the nanowires and the nanoparticles typically produced separately and then integrated. The few existent single-step methods are lengthy or necessitate highly dedicated setups. In this paper we report a single-step and rapid (ca. 1 min) laser ablation synthesis method which produces a wide variety of boron-rich decorated nanowires. Furthermore, the method is carried at room temperature. The synthesis process consists on a filamentary jet ejection process driven by pressure gradients generated by the ablation plume on the rims of the irradiation crater. Simultaneously nanoparticles are nucleated and deposited on the filaments thus producing hybrid decorated nanowires.
- ItemAn efficient two-polymer binder for high-performance silicon nanoparticle-based lithium-ion batteries: A systematic case study with commercial polyacrylic acid and polyvinyl butyral polymers(Pennington, NJ : Electrochemical Society Inc., 2019) Urbanski, A.; Omar, A.; Guo, J.; Janke, A.; Reuter, U.; Malanin, M.; Schmidt, F.; Jehnichen, D.; Holzschuh, M.; Simon, F.; Eichhorn, K.-J.; Giebeler, L.; Uhlmann, P.Silicon is one of the most promising anode materials for high energy density lithium ion batteries (LIBs) due to its high theoretical capacity and natural abundance. Unfortunately, significant challenges arise due to the large volume change of silicon upon lithiation/delithiation which inhibit its broad commercialization. An advanced binder can, in principle, reversibly buffer the volume change, and maintain strong adhesion toward various components as well as the current collector. In this work, we present the first report on the applicability of polyvinyl butyral (PVB) polymer as a binder component for silicon nanoparticles-based LIBs. Characteristic binder properties of commercial PVB and polyacrylic acid (PAA) polymers are compared. The work focuses on polymer mixtures of PVB polymers with PAA, for an improved binder composition which incorporates their individual advantages. Different ratios of polymers are systematically studied to understand the effect of particular polymer chains, functional groups and mass fractions, on the electrochemical performance. We demonstrate a high-performance polymer mixture which exhibits good binder-particle interaction and strong adhesion to Cu-foil. PAA/PVB-based electrode with a Si loading of ∼1 mg/cm2 tested between 0.01 and 1.2 V vs. Li/Li+ demonstrate specific capacities as high as 2170 mAh/g after the first hundred cycles. © The Author(s) 2019.
- ItemElectrical and magnetic properties of NiTiO3 nanoparticles synthesized by the sol-gel synthesis method and microwave sintering(Amsterdam : Elsevier B.V., 2019) Pavithra, C.; Madhuri, W.In this paper, we focused on microwave sintered NiTiO3 nanoparticles synthesized via sol-gel method. The crystal structure was determined by the X-ray diffraction. Vibrational bands related to Ni-O and Ti-O bands were confirmed using the Fourier transform infrared spectrum. These NiTiO3 ceramics obeyed semiconductor behavior of Arrhenius type. The activation energy was found to be 0.04 μeV. The M-H curve exhibited superparamagnetic behavior at room temperature.
- ItemTime-resolved study of site-specific corrosion in a single crystalline silver nanoparticle(Berlin : SpringerOpen, 2019) Trautmann, Steffen; Dathe, André; Csáki, Andrea; Thiele, Matthias; Müller, Robert; Fritzsche, Wolfgang; Stranik, OndrejWe followed over 24 h a corrosion process in monocrystalline triangular-shaped nanoparticles at a single-particle level by atomic force microscopy and optical spectroscopy techniques under ambient laboratory conditions. The triangular-shaped form of the particles was selected, because the crystallographic orientation of the particles is well defined upon their deposition on a substrate. We observed that the particles already start to alter within this time frame. Surprisingly, the corrosion starts predominantly from the tips of the particles and it creates within few hours large protrusions, which strongly suppress the plasmon character of the particles. These observations support the crystallographic model of these particles consisting of a high-defect hexagonal closed packed layer, and they could help material scientists to design more stable silver nanoparticles. Moreover, this described technique can be used to reveal kinetics of the corrosion in the nanoscale of other materials.
- ItemZnO Nanoparticles Encapsulated in Nitrogen-Doped Carbon Material and Silicalite-1 Composites for Efficient Propane Dehydrogenation(Amsterdam [u.a.] : Elsevier, 2019) Zhao, Dan; Li, Yuming; Han, Shanlei; Zhang, Yaoyuan; Jiang, Guiyuan; Wang, Yajun; Guo, Ke; Zhao, Zhen; Xu, Chunming; Li, Ranjia; Yu, Changchun; Zhang, Jian; Ge, Binghui; Kondratenko, Evgenii V.Chemistry; Catalysis; Nanoparticles © 2019 The Author(s)Non-oxidative propane dehydrogenation (PDH)is an attractive reaction from both an industrial and a scientific viewpoint because it allows direct large-scale production of propene and fundamental analysis of C-H activation respectively. The main challenges are related to achieving high activity, selectivity, and on-stream stability of environment-friendly and cost-efficient catalysts without non-noble metals. Here, we describe an approach for the preparation of supported ultrasmall ZnO nanoparticles (2–4 nm, ZnO NPs)for high-temperature applications. The approach consists of encapsulation of NPs into a nitrogen-doped carbon (NC)layer in situ grown from zeolitic imidazolate framework-8 on a Silicalite-1 support. The NC layer was established to control the size of ZnO NPs and to hinder their loss to a large extent at high temperatures. The designed catalysts exhibited high activity, selectivity, and on-stream stability in PDH. Propene selectivity of about 90% at 44.4% propane conversion was achieved at 600°C after nearly 6 h on stream. © 2019 The Author(s)
- ItemNovel monomers in radical ring-opening polymerisation for biodegradable and pH responsive nanoparticles(Brookfield, Conn. : Society of Plastic Engineers, 2019) Folini, Jenny; Huang, Chao-Hung; Anderson, James C.; Meier, Wolfgang P.; Gaitzsch, JensResponsive and biodegradable nanoparticles are essential for functional drug delivery systems. We herein report the first pH sensitive polyester from radical ring-opening polymerisation of novel amine-bearing cyclic ketene acetals (CKAs). The CKAs were synthesised via an intermediate carbonate and the resulting polyesters showed a pKa around pH 6. Together with an initial application in biodegradable nanoparticles, they open the pathway for a new generation of functional polyesters.
- ItemThe synergistic effect of chlorotoxin-mApoE in boosting drug-loaded liposomes across the BBB(London : BioMed Central, 2019) Formicola, Beatrice; Dal, Magro, Roberta; Montefusco-Pereira, Carlos V.; Lehr, Claus‑Michael; Koch, Marcus; Russo, Laura; Grasso, Gianvito; Deriu, Marco A.; Danani, Andrea; Bourdoulous, Sandrine; Re, FrancescaWe designed liposomes dually functionalized with ApoE-derived peptide (mApoE) and chlorotoxin (ClTx) to improve their blood-brain barrier (BBB) crossing. Our results demonstrated the synergistic activity of ClTx-mApoE in boosting doxorubicin-loaded liposomes across the BBB, keeping the anti-tumour activity of the drug loaded: mApoE acts promoting cellular uptake, while ClTx promotes exocytosis of liposomes. © 2019 The Author(s).
- ItemSERS and plasmonic heating efficiency from anisotropic core/satellite superstructures(Cambridge : RSC Publ., 2019) Kuttner, Christian; Höller, Roland P. M.; Quintanilla, Marta; Schnepf, Max J.; Dulle, Martin; Fery, Andreas; Liz-Marzán, Luis M.The optical properties of nanoparticle assemblies can be tailored via hybridization of plasmon modes. Isotropic core/satellite superstructures made of spherical nanoparticles are known to exhibit coupled modes with a strongly scattering (radiative) character, and provide hot spots yielding high activity in surface-enhanced Raman scattering (SERS). However, to complement this functionality with plasmonic heating, additional absorbing (non-radiative) modes are required. We introduce herein anisotropic superstructures formed by decorating a central nanorod with spherical satellite nanoparticles, which feature two coupled modes that allow application for both SERS and heating. On the basis of diffuse reflectance spectroscopy, small-angle X-ray scattering (SAXS), and electromagnetic simulations, the origin of the coupled modes is disclosed and thus serves as a basis toward alternative designs of functional superstructures. This work represents a proof-of-principle for the combination of high SERS efficiency with efficient plasmonic heating by near-infrared irradiation.
- ItemCytotoxicity of dendrimers(Basel : MDPI, 2019) Janaszewska, Anna; Lazniewska, Joanna; Trzepiński, Przemysław; Klajnert-Maculewicz, BarbaraDrug delivery systems are molecular platforms in which an active compound is packed into or loaded on a biocompatible nanoparticle. Such a solution improves the activity of the applied drug or decreases its side effects. Dendrimers are promising molecular platforms for drug delivery due to their unique properties. These macromolecules are known for their defined size, shape, and molecular weight, as well as their monodispersity, the presence of the void space, tailorable structure, internalization by cells, selectivity toward cells and intracellular components, protection of guest molecules, and controllable release of the cargo. Dendrimers were tested as carriers of various molecules and, simultaneously, their toxicity was examined using different cell lines. It was discovered that, in general, dendrimer cytotoxicity depended on the generation, the number of surface groups, and the nature of terminal moieties (anionic, neutral, or cationic). Higher cytotoxicity occurred for higher-generation dendrimers and for dendrimers with positive charges on the surface. In order to decrease the cytotoxicity of dendrimers, scientists started to introduce different chemical modifications on the periphery of the nanomolecule. Dendrimers grafted with polyethylene glycol (PEG), acetyl groups, carbohydrates, and other moieties did not affect cell viability, or did so only slightly, while still maintaining other advantageous properties. Dendrimers clearly have great potential for wide utilization as drug and gene carriers. Moreover, some dendrimers have biological properties per se, being anti-fungal, anti-bacterial, or toxic to cancer cells without affecting normal cells. Therefore, intrinsic cytotoxicity is a comprehensive problem and should be considered individually depending on the potential destination of the nanoparticle. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.