Highlight Publications 2020

Composition-Dependent Passivation Efficiency at the CdS/CuIn1-xGaxSe2 Interface
Marco Ballabio, David Fuertes Marrón, Nicolas Barreau, Mischa Bonn, and Enrique Cánovas
Composition-Dependent Passivation Efficiency at the CdS/CuIn1-xGaxSe2 Interface
Copper-indium-gallium diselenide (CIGS) is an attractive semiconductor with a tuneable bandgap that depends on the indium-to-gallium ratio. The possibility to engineer the bandgap makes CIGS highly relevant for photovoltaics, since the solar energy conversion can be maximised. However, devices with optimally tailored bandgap, containing high levels of gallium, exhibit a sofar not understood drop in efficiency, which limits the full potential of this material. Herein, we demonstrate that traditional CdS surface passivation prevents surface recombination of charge carriers only for low Ga content, while surface recombination dominates for higher-bandgap materials. A replacement for the CdS layer could, therefore, provide a way forward for further increasing the efficiency of CIGS solar cells.
© Wiley (2020)
The effect of surface passivation depends on bulk composition in Copper-indium-gallium diselenide (CIGS).
Amphiphilic Polyphenylene Dendron Conjugates for Surface Remodeling of Adenovirus 5
Jessica Wagner, Longjie Li, Johanna Simon, Lea Krutzke, Katharina Landfester, Volker Mailänder, Klaus Müllen, David Y.W. Ng, Yuzhou Wu, Tanja Weil
Amphiphilic Polyphenylene Dendron Conjugates for Surface Remodeling of Adenovirus 5
A arrangement of amphiphilic surface groups play an important role in many biological processes such as protein folding or biorecognition. We report the synthesis of amphiphilic polyphenylene dendrimer branches (dendrons) providing alternating hydrophilic and lipophilic surface groups and one reactive enthynyl group at the core. The amphiphilic surface groups serve as biorecognition units that bind to the surface of adenovirus 5 (Ad5), which is one of the most common vectors in gene therapy. The Ad5/dendron complexes showed high gene transduction efficiencies in coxsackie-adenovirus receptor (CAR)-negative cells. Moreover, the dendrons offer incorporating new functions at the dendron core by in situ post-modifications even when bound to the Ad5 surface. Surfaces coated with these amphiphilic dendrons were analyzed for their blood protein binding capacity, which is essential to predict their performance in the blood stream. In this way, we provide a new platform for introducing bioactive groups to the Ad5 surface without the necessity to chemically modify the virus particles.
© The Authors (2020)
Amphiphilic polyphenylene dendrons bind to adenovirus 5 through polar and nonpolar surface groups and control its cellular uptake. The new dendron layer provides reactive groups for post-modifications at the virus surface.
Precision Anisotropic Brush Polymers by Sequence Controlled Chemistry
Chaojian Chen, Katrin Wunderlich, Debashish Mukherji, Kaloian Koynov, Astrid Johanna Heck, Marco Raabe, Matthias Barz, George Fytas, Kurt Kremer, David Yuen Wah Ng, and Tanja Weil
Precision Anisotropic Brush Polymers by Sequence Controlled Chemistry
The programming of nanomaterials at molecular length-scales to control architecture and function represents a pinnacle in soft materials syntheses. We show that biomolecules, specifically proteins, provide an intrinsic macromolecular backbone for the construction of anisotropic brush polymers with monodisperse lengths via grafting-from strategy. Using human serum albumin as a model, its sequence was exploited to chemically transform a single cysteine, such that any functionality can be asymmetrically placed along the backbone of the eventual brush polymer. Combining this with biotin-streptavidin interactions, we demonstrate the capabilities for site-specific self-assembly to create higher ordered architectures. Supported by systematic experimental and computational studies, we envisioned that this macromolecular platform provides unique avenues and perspectives in macromolecular design for both nanoscience and biomedicine.
© (2020)
Proteins are unfolded to form a monodispersed template for the preparation of precision brush polymers.
One-Step Preparation of Fuel-Containing Anisotropic Nanocapsules with Stimuli-Regulated Propulsion
Shuai Jiang, Anke Kaltbeitzel, Minghan Hu, Oksana Suraeva, Daniel Crespy, Katharina Landfester
One-Step Preparation of Fuel-Containing Anisotropic Nanocapsules with Stimuli-Regulated Propulsion
One of the dreams of nanotechnology is to create tiny objects, nanobots, that are able to perform difficult tasks in dimensions and locations that are not directly accessible. One basic function of these nanobots is motility. Movements created by self-propelled micro- and nanovehicles are usually dependent on the production of propellants from catalytic reactions of fuels present in the environment. Developing self-powered nanovehicles with internally stored fuels that display motion regulated by external stimuli represents an intriguing and challenging alternative. Herein, a one-step preparation of fuel-containing nanovehicles that feature a motion that can be regulated by external stimuli is reported. Nanovehicles are prepared via a sol–gel process confined at the oil/water interface of miniemulsions. The nanovehicles display shapes ranging from mushroom-like to truncated cones and a core–shell structure so that the silica shell acts as a hull for the nanovehicles while the core is used to store the fuel. Azo-based initiators are loaded in the nanovehicles, which are activated to release nitrogen gas upon increase of temperature or exposure to UV light. Enhanced diffusion of nanovehicles is achieved upon decomposition of the fuel.
© ACS Publications (2020)
Nature of Excess Hydrated Proton at the Water–Air Interface
Sudipta Das, Sho Imoto, Shumei Sun, Yuki Nagata, Ellen H. G. Backus,and Mischa Bonn
Nature of Excess Hydrated Proton at the Water–Air Interface
Understanding the interfacial molecular structure of acidic aqueous solutions is important in the context of, e.g., atmospheric chemistry, biophysics, and electrochemistry. The hydration of the interfacial proton is necessarily different from that in the bulk, given the lower effective density of water at the interface, and is elucidated here for the first time. Combined experiments and simulations reveal that the proton at the water-air interface is well-hydrated, despite the limited availability of hydration water, with both Eigen and Zundel structures coexisting at the interface. A substantial interfacial stabilization by -1.3±0.2 kcal/mol is observed experimentally, in good agreement with our free energy calculations.
© MPI-P (2020)
Structure of protons at the water interface revealed for the first time
 
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