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End date: 2019 × Publisher: Weinheim : Wiley-VCH × Subject: nanoparticles ×

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    Photo-Cross-Linked Dual-Responsive Hollow Capsules Mimicking Cell Membrane for Controllable Cargo Post-Encapsulation and Release
    (Weinheim : Wiley-VCH, 2016) Liu, Xiaoling; Appelhans, Dietmar; Wei, Qiang; Voit, Brigitte
    Multifunctional and responsive hollow capsules are ideal candidates to establish highly sophisticated compartments mimicking cell membranes for controllable bio-inspired functions. For this purpose pH and temperature dual-responsive and photo-cross-linked hollow capsules, based on silica-templated layer-by-layer approach by using poly(N-isopropyl acrylamide)-blockpolymethacrylate) and polyallylamine, have been prepared to use them for the subsequent and easily available post-encapsulation process of proteinlike macromolecules at room temperature and pH 7.4 and their controllable release triggered by stimuli. The uptake and release properties of the hollow capsules for cargos are highly affected by changes in the external stimuli temperature (25, 37, or 45 °C) and internal stimuli pH of the phosphate-containing buffer solution (5.5 or 7.4), by the degree of photo-cross-linking, and the size of cargo. The photo-cross-linked and dual stimuli-responsive hollow capsules with different membrane permeability can be considered as attractive material for mimicking cell functions triggered by controllable uptake and release of different up to 11 nm sized biomolecules.
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    Mechanism of Bi−Ni Phase Formation in a Microwave-Assisted Polyol Process
    (Weinheim : Wiley-VCH, 2019) Smuda, Matthias; Damm, Christine; Ruck, Michael; Doert, Thomas
    Typically, intermetallic phases are obtained in solid-state reactions or crystallization from melts, which are highly energy and time consuming. The polyol process takes advantage of low temperatures and short reaction times using easily obtainable starting materials. The formation mechanism of these intermetallic particles has received little attention so far, even though a deeper understanding should allow for better synthesis planning. In this study, we therefore investigated the formation of BiNi particles in ethylene glycol in a microwave-assisted polyol process mechanistically. The coordination behavior in solution was analyzed using HPLC-MS and UV-Vis. Tracking the reaction with PXRD measurements, FT-IR spectroscopy and HR-TEM revealed a successive reduction of Bi3+ and Ni2+, leading to novel spherical core-shell structure in a first reaction step. Bismuth particles are encased in a matrix of nickel nanoparticles of 2 nm to 6 nm in diameter and oxidation products of ethylene glycol. Step-wise diffusion of nickel into the bismuth particle intermediately results in the bismuth-rich compound Bi3Ni, which consecutively transforms into the BiNi phase as the reaction progresses. The impacts of the anion type, temperature and pH value were also investigated. © 2020 The Authors. Published by Wiley-VCH GmbH
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    Water-Soluble Polymeric Carbon Nitride Colloidal Nanoparticles for Highly Selective Quasi-Homogeneous Photocatalysis
    (Weinheim : Wiley-VCH, 2019) Krivtsov, Igor; Mitoraj, Dariusz; Adler, Christiane; Ilkaeva, Marina; Sardo, Mariana; Mafra, Luis; Neumann, Christof; Turchanin, Andrey; Li, Chunyu; Dietzek, Benjamin; Leiter, Robert; Biskupek, Johannes; Kaiser, Ute; Im, Changbin; Kirchhoff, Björn; Jacob, Timo; Beranek, Radim
    Heptazine-based polymeric carbon nitrides (PCN) are promising photocatalysts for light-driven redox transformations. However, their activity is hampered by low surface area resulting in low concentration of accessible active sites. Herein, we report a bottom-up preparation of PCN nanoparticles with a narrow size distribution (ca. 10±3 nm), which are fully soluble in water showing no gelation or precipitation over several months. They allow photocatalysis to be carried out under quasi-homogeneous conditions. The superior performance of water-soluble PCN, compared to conventional solid PCN, is shown in photocatalytic H2O2 production via reduction of oxygen accompanied by highly selective photooxidation of 4-methoxybenzyl alcohol and benzyl alcohol or lignocellulose-derived feedstock (ethanol, glycerol, glucose). The dissolved photocatalyst can be easily recovered and re-dissolved by simple modulation of the ionic strength of the medium, without any loss of activity and selectivity. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.