Highlight Publications 2017

Edge Functionalization of Structurally Defined Graphene Nanoribbons for Modulating the Self- Assembled Structures
Ashok Keerthi, Boya Radha, Daniele Rizzo, Hao Lu, Valentin Diez Cabanes, Ian Cheng-Yi Hou, David Beljonne, Jérôme Cornil, Cinzia Casiraghi, Martin Baumgarten, Klaus Müllen, Akimitsu Narita
Edge Functionalization of Structurally Defined Graphene Nanoribbons for Modulating the Self- Assembled Structures
Edge functionalization of bottom-up synthesized graphene nanoribbons (GNRs) with anthraquinone (AQ) and naphthalene/perylene monoimide (NMI/PMI) units has been achieved through a Suzuki coupling of polyphenylene precursors bearing bromo groups, prior to the intramolecular oxidative cyclodehydrogenation. High efficiency of the substitution has been validated by MALDI-TOF MS analysis of the functionalized precursors and FT-IR, Raman and XPS analyses of the resulting GNRs. Moreover, AFM measurements demonstrated the modulation of the self-assembling behavior of the edge-functionalized GNRs, revealing that GNR-PMI formed an intriguing rectangular network. This result suggests the possibility of programming the supramolecular architecture of GNRs by tuning the functional units.
© ACS (2017)
Structure and unique self-assembled structure of GNR-PMI visualized by atomic force microscope.
Exploration of pyrazine-embedded antiaromatic polycyclic hydrocarbons generated by solution and on-surface azomethine ylide homocoupling
Xiao-Ye Wang, Marcus Richter, Yuanqin He, Jonas Björk, Alexander Riss, Raju Rajesh, Manuela Garnica, Felix Hennersdorf, Jan J. Weigand, Akimitsu Narita, Reinhard Berger, Xinliang Feng, Willi Auwärter, Johannes V. Barth, Carlos-Andres Palma, Klaus Müllen
Exploration of pyrazine-embedded antiaromatic polycyclic hydrocarbons generated by solution and on-surface azomethine ylide homocoupling
Nanographenes, namely polycyclic aromatic hydrocarbons (PAHs) with nanoscale dimensions (>1 nm), are atomically precise cutouts from graphene. They represent prime models to enhance the scope of chemical and physical properties of graphene through structural modulation and functionalization. Defined nitrogen doping in nanographenes is particularly attractive due to its potential for increasing the number of π-electrons, with the possibility of introducing localized antiaromatic ring elements. Herein we present azomethine ylide homocoupling as a strategy to afford internally nitrogen-doped, non-planar PAH in solution and planar nanographene on surfaces, with central pyrazine rings. Localized antiaromaticity of the central ring is indicated by optical absorption spectroscopy in conjunction with theoretical calculations. Our strategy opens up methods for chemically tailoring graphene and nanographenes, modified by antiaromatic dopants.
© Nature Publishing Group (2017)
Exploration of pyrazine-embedded antiaromatic polycyclic hydrocarbons
Controlling the polymer microstructure in anionic polymerization by compartmentalization
Elisabeth Rieger, Jan Blankenburg, Eduard Grune, Manfred Wagner, Katharina Landfester, and Frederik R. Wurm
Controlling the polymer microstructure in anionic polymerization by compartmentalization
Compartmentalization is the spatial separation of reagents inside of organisms, which allows nature to prepare complex molecules. In contrast, polymer chemistry normally uses sequential monomer addition to prepare macromolecular architectures. In the synthesis lab an emulsion is the easiest way of confining a reaction: we use an emulsion template to force an ideal (random) copolymerization of two comonomers into gradient copolymers in a one-pot and one-shot reaction, without the need for sequential monomer addition. Physical separation of the two monomers is achieved by selective solubility in the dispersed and the continuous phase to control the incorporation probability of both monomers. In addition, confinement of the propagation to the nano-droplets allows further tuning of the gradient by different levels of dilution of the continuous phase.
© Wiley VCH (2017)
Schematic representation of homogeneous copolymerization to random, and emulsion copolymerization to gradient copolymers from the same monomer pair.
Fabrication of defined polydopamine nanostructures by DNA origami-templated polymerization
Yu Tokura, Sean Harvey, Chaojian Chen, Yuzhou Wu, David Y.W. Ng, Tanja Weil
Fabrication of defined polydopamine nanostructures by DNA origami-templated polymerization
A versatile, bottom-up approach allows the controlled fabrication of polydopamine (PD) nanostructures on DNA origami. PD is a biosynthetic polymer that has been investigated as an adhesive and promising surface coating material. DNA origami decorated with multiple horseradish peroxidase-mimicking DNAzyme motifs was used to control the shape and size of PD formation with nanometer resolution. These fabricated PD nanostructures can serve as “supramolecular glue” for controlling DNA origami conformations. Facile liberation of the PD nanostructures from the DNA origami templates has been achieved in acidic medium. This presented DNA origami-controlled polymerization of a highly crosslinked polymer provides a unique access towards anisotropic PD architectures with distinct shapes that were retained even in the absence of the DNA origami template.
© Wiley VCH (2017)
Nanofabrication of Precise Polydopamine Architectures
Directing Intracellular Supramolecular Assembly with N-heteroaromatic Quaterthiophene Analogues
David Y.W. Ng, Roman Vill, Yuzhou Wu, Kaloian Koynov, Yu Tokura, Weina Liu, Susanne Sihler, Andreas Kreyes, Sandra Ritz, Holger Barth, Ulrich Ziener, Tanja Weil
Directing Intracellular Supramolecular Assembly with N-heteroaromatic Quaterthiophene Analogues
Self-assembly in situ, where synthetic molecules are programmed to organize in a complex environment can be a unique strategy to influence cellular functions. Here we present oligothiophene analogues that target, locate and dynamically self-report their supramolecular behavior within the confinement of a cell. Through the recognition of their chemical structure, we show that the cell provides different pathways for self-assembly that are traced with fluorescence microscopy. Their molecular organization emits in distinct fluorescent bands and the control each form is achieved by time, temperature as well as the use of the intracellular transport inhibitor, bafilomycin A1. We show the importance of both intrinsic and extrinsic factors for self-organization and the potential of such a platform toward developing synthetic functional components within living cells.
© David Ng / MPI-P (2017)
Overview of cellular pathways and its influence on self-organization of the oligothiophene analogues
Biological fabrication of cellulose fibers with tailored properties
Filipe Natalio, Regina Fuchs, Sidney R. Cohen, Gregory Leitus, Gerhard Fritz-Popovski, Oskar Paris, Michael Kappl, Hans-Jürgen Butt
Biological fabrication of cellulose fibers with tailored properties
Filipe Natalio from the Weizmann Institute of Science Israel, together with colleagues from the MPI-P and from Leoben, Austria, developed a method for biofabrication of functional cotton. Cotton ovules, were incubated in media containing glucose molecules (the molecular building blocks of cellulose fibers) that were specifically modified. Dye molecules or molecular magnets linked to glucose were taken up by the ovules and metabolized into cellulose fibers that became colored or exhibiting magnetic response. This new concept of material farming opens perspectives for plant based biofabrication of functional materials without genetic modifications.
© Filipe Natalio (2017)
Optical microscopy image of cotton fibers containing a fluorescent dye. Dye molecules were integrated into fibers via the metabolic pathways of cotton ovules, incubating them with specifically designed glucose molecules containing the dye.
Processing of ferroelectric polymers for microelectronics: from morphological analysis to functional devices
Hamed Sharifi, Jasper Michels, Kamal Asadi
Processing of ferroelectric polymers for microelectronics: from morphological analysis to functional devices
Organic memory devices are of great interest for flexible and cost-effective thin-film applications, such as RFID tags. However, a low cost production is only guaranteed if processing occurs under ambient, and therefore “humid”, conditions. It is known that solutions containing the fluorinated polyethylenes used for such applications, demix upon ingress of ambient water vapor into the coated film. This “vapor-induced phase separation” causes porous dry layers, desirable in case of, for instance, membrane technology, but to be avoided in thin-film electronics. Via an amalgamation of morphological mapping, device physics and modeling of demixing dynamics, we demonstrate how the hygroscopicity of the solvent crucially determines dry film morphology. For a sufficiently low solvent hygroscopicity, a >90% yield of functioning memory devices has been obtained at ambient conditions.
© RSC (2017)
A combination of morphological analysis and numerical simulation of solution phase behavior elucidates the relation between ambient humidity, solvent hygroscopicity and thin-film memory device performance.
Thermal conductivity and air-mediated losses in periodic porous silicon membranes at high temperatures
B. Graczykowski, A. El Sachat, J. S. Reparaz, M. Sledzinska, M. R. Wagner, E. Chavez-Angel, Y. Wu, S. Volz, F. Alzina & C. M. Sotomayor Torres
Thermal conductivity and air-mediated losses in periodic porous silicon membranes at high temperatures
Heat conduction in silicon can be effectively engineered by means of sub-micrometre porous free- standing membranes. Tunable thermal properties make these structures good candidates for integrated heat management units. In this work we use the two-laser Raman thermometry to study heat dissipation in periodic porous membranes at high temperatures via lattice conduction and air-mediated losses. We find the reduction of the thermal conductivity and its temperature dependence correlated with the structure feature size. On the basis of two-phonon Raman spectra, we attribute this behaviour to diffuse phonon-boundary scattering. Furthermore, we quantify the heat dissipation via natural air-mediated cooling, which can be tuned by engineering the porosity.
© Bartlomiej Graczykowski / MPI-P (2017)
Schematics of the two-laser Raman thermometry experiment performed on periodic porous Si membarnes.
Direct observation of mode-specific phonon-band gap coupling in methylammonium lead halide perovskites
Heejae Kim, Johannes Hunger, Enrique Cánovas, Melike Karakus, Zoltán Mics, Maksim Grechko, Dmitry Turchinovich, Sapun H. Parekh & Mischa Bonn
Direct observation of mode-specific phonon-band gap coupling in methylammonium lead halide perovskites
Methylammonium lead iodide perovskite is well-known not only for its remarkable rise of the power conversion efficiency in photovoltaic applications, but also for its peculiar photo-physical properties. We have investigated one of the intriguing peculiarities: the positive temperature dependence of the optical band gap. By the time-resolved THz/optical spectroscopy, we were able to observe a blue shift of the absorption onset after ~1 THz vibrational mode was excited. Theoretical modelling approaches assisted us to identify the specific phonon mode from the experimental results. We showed that the particular vibration, which governs the angle between lead and iodide ionic bonds, contributes to the unusual temperature dependent light absorption of this perovskite.
© Heejae Kim / MPI-P (2017)
Figure Caption: Selective excitation of the ~ 1 THz phonon mode, which corresponds to the Pb-I-Pb angle, induces the transient increase of the optical band gap.
Spontaneous jumping, bouncing and trampolining of hydrogel drops on a heated place
Jonathan T. Pham, Maxime Paven, Sanghyuk Wooh, Tadashi Kajiya, Hans-Jürgen Butt, Doris Vollmer
Spontaneous jumping, bouncing and trampolining of hydrogel drops on a heated place
The contact between liquid drops and hot solid surfaces is of practical importance for industrial processes, such as thermal spraying and spray cooling. The contact and bouncing of solid spheres is also an important event encountered in ball milling, powder processing, and everyday activities, such as ball sports. Using high speed video microscopy, we demonstrate that hydrogel drops, initially at rest on a surface, spontaneously jump upon rapid heating and continue to bounce with increasing amplitudes. Jumping is governed by the surface wettability, surface temperature, hydrogel elasticity, and adhesion. A combination of low adhesion impact behavior and fast water vapor formation supports continuous bouncing and trampolining. Our results illustrate how the interplay between solid and liquid characteristics of hydrogels results in intriguing dynamics, as reflected by spontaneous jumping, bouncing, trampolining, and extremely short contact times.
© Jonathan Pham / MPI-P (2017)
A hydrogel drop spontaneously jumps from tungsten surface upon rapidly heating the surface.
Short-channel field-effect transistors with 9-atom and 13-atom wide graphene nanoribbons
Juan Pablo Llinas, Andrew Fairbrother, Gabriela Borin Barin, Wu Shi, Kyunghoon Lee, Shuang Wu, Byung Yong Choi, Rohit Braganza, Jordan Lear, Nicholas Kau, Wonwoo Choi, Chen Chen, Zahra Pedramrazi, Tim Dumslaff, Akimitsu Narita, Xinliang Feng, Klaus Müllen, Felix Fischer, Alex Zettl, Pascal Ruffieux, Eli Yablonovitch1, Michael Crommie, Roman Fasel & Jeffrey Bokor
Short-channel field-effect transistors with 9-atom and 13-atom wide graphene nanoribbons
Bottom-up synthesized graphene nanoribbons (GNRs) and GNR heterostructures have promising electronic properties for high-performance field-effect transistors (FETs) and ultra-low power devices such as tunneling FETs. However, the short length and wide band gap of GNRs have prevented the fabrication of devices with the desired performance and switching behavior. Here, by fabricating short channel devices with a thin, high-κ gate dielectric and a 9-atom wide armchair GNR as the channel material, we demonstrate field-effect transistors with high on-current and high I on /I off  at room temperature. We find that the performance of these devices is limited by tunneling through the Schottky barrier at the contacts and we observe an increase in the transparency of the barrier by increasing the gate field near the contacts. Our results thus demonstrate successful fabrication of high-performance short-channel FETs with bottom-up synthesized armchair GNRs.
© Nature Publishing Group (2017)
Schematic of the short channel GNRFET with a 9AGNR channel and Pd source-drain electrodes (top) and Scanning electron micrograph of the fabricated Pd source-drain electrodes with a scale bar of 100 nm (bottom)
A maximum in interfacial hydrogen bonding occurs at 200 K at the single crystalline ice – air interface.
Wilbert J. Smit, Fujie Tang, M. Alejandra Sánchez, Ellen H. G. Backus, Limei Xu, Taisuke Hasegawa, Mischa Bonn, Huib J. Bakker, and Yuki Nagata
A maximum in interfacial hydrogen bonding occurs at 200 K at the single crystalline ice – air interface.
Combining theory and experiment, we have studied the temperature dependent structure of water molecules at the surface of ice. Remarkably, a maximum in interfacial hydrogen bonding occurs at 200 K. This maximum results from two competing effects: above 200 K, thermal fluctuations cause the breaking of hydrogen bonds; below 200 K, the ordered crystalline bulk structure causes breaking of hydrogen bonds at the interface. These insights are particularly important for understanding (photo-) chemistry occurring on ice particles in the atmosphere.
© Yuki Nagata / MPI-P (2017)
Ice forms crystal structure even at topmost ice surface at 170 K, while ice structure becomes disordered at 230 K. At 200 K, ice forms maximum hydrogen bond by making five-ring structure rather than hexagonal structure.
Reversible Self-Assembly of Degradable Polymersomes with Upper Critical Solution Temperature in Water
Thomas Wolf, Timo Rheinberger, Johanna Simon, Frederik R. Wurm
Reversible Self-Assembly of Degradable Polymersomes with Upper Critical Solution Temperature in Water
Temperature-induced self-assembly of block copolymers allows the formation of smart nanodimensional structures. Mostly, non-degradable LCST segments are used to prepare such dynamic aggregates. However, degradable UCST block copolymers that would allow the swelling or disassembly at elevated temperatures with eventual backbone hydrolysis have not been reported to date. We present the first well-defined degradable poly(phosphonate)s with adjustable UCST in water between 43 °C and 71 °C. Block copolymers with PEG self-assemble into well-defined polymersomes. Depending on the responsive block, these structures either swell or disassemble completely upon an increased temperature.
© ACS (2017)
Upper critical solution temperature in degradable poly(phosphoester)s was installed to prepare block copolymer vesicles that self-assemble at room temperature and reversibly disassemble at elevated temperatures.
A Conjugated Microporous Polymer for Palladium-Free, Visible Light-Promoted Photocatalytic Stille-Type Coupling Reactions
Saman Ghasimi, Simon A. Bretschneider, Wei Huang, Katharina Landfester, and Kai A. I. Zhang
A Conjugated Microporous Polymer for Palladium-Free, Visible Light-Promoted Photocatalytic Stille-Type Coupling Reactions
The Stille coupling reaction is a versatile method to mainly form aromatic C-C bonds. However, up to now, the use of palladium catalysts is necessary. Researchers from the MPI-P reported a palladium-free and photocatalytic Stille-type coupling route between aryl iodides and aryl stannanes. The new coupling reaction pathway is catalyzed by a conjugated microporous polymer under visible light irradiation at room temperature. The novel coupling reaction mechanism occurs between the photogenerated aryl radical under oxidative destannylation of the aryl stannane, and the electron-activated aryl iodide, resulting into the aromatic C-C bond formation reaction.
© Wiley VCH (2017)
Bye-Bye Palladium: A photocatalytic, palladium-free Stille-type coupling reaction is described.
A triaxial supramolecular weave
Urszula Lewandowska, Wojciech Zajaczkowski, Stefano Corra, Junki Tanabe,Ruediger Borrmann, Edmondo M. Benetti, Sebastian Stappert, Kohei Watanabe, Nellie A. K. Ochs, Robin Schaeublin, Chen Li, Eiji Yashima, Wojciech Pisula, Klaus Müllen & Helma Wennemers
A triaxial supramolecular weave
Despite recent advances in the synthesis of increasingly complex topologies at the molecular level, nano- and microscopic weaves have remained difficult to achieve. Only a few diaxial molecular weaves exist these were achieved by templation with metals. Here, we present an extended triaxial supramolecular weave that consists of self-assembled organic threads. Each thread is formed by the self-assembly of a building block comprising a rigid oligoproline segment with two perylene-monoimide chromophores spaced at 18 Å. Upon π stacking of the chromophores, threads form that feature alternating up- and down-facing voids at regular distances. These voids accommodate incoming building blocks and establish crossing points through CH–π interactions on further assembly of the threads into a triaxial woven superstructure. The resulting micrometer-scale supramolecular weave proved to be more robust than non-woven self-assemblies of the same building block. The uniform hexagonal pores of the interwoven network were able to host iridium nanoparticles, which may be of interest for practical applications.
© Helma Wennemers/ETH und Klaus Müllen/MPI-P (2017)
Woven topologies endow macroscopic objects with mechanical stability, but their molecular counterparts have remained difficult to prepare. Now, an extended triaxial supramolecular weave has been formed by the self-assembly of a judiciously shaped organic building block - a rigid oligoproline segment featuring two perylene-monoimide moieties - through π-π stacking and CH-π interactions.
Diffusion and Permeation of Labeled IgG in Grafted Hydrogels
A. Vagias,K. Sergelen,K. Koynov,P. Košovan,J. Dostalek,U. Jonas,W. Knoll,and G. Fytas
Diffusion and Permeation of Labeled IgG in Grafted Hydrogels
The transport of antibodies through hydrogel materials is of fundamental relevance for many biological systems, but equally important in medical and technological applications. With this in mind we used fluorescence correlation spectroscopy (FCS) to study the permeation and diffusion of immunoglobulin G (IgG) in model hydrogel layers based on thermo-responsive poly(N-isopropylacrylamide) (pNiPAAm). Our findings demonstrated the outmost importance of the various interactions between proteins and the polymer network and suggest a model approach to explore the synergy between crowding and thermodynamics with respect to the controlled protein transport in pNiPAAm-based hydrogels.
© ACS (2017)
Schematic illustration of the variability of IgG and PNiPAAm interactions, depending on external stimulus employed: pH, ionic strength (I), temperature (T). IgG trajectory through the FCS focal spot is also depicted.
Solution-Processable High-Quality Graphene for Organic Solar Cells
Antonio Gaetano Ricciardulli, Sheng Yang, Xinliang Feng, Paul W. M. Blom
Solution-Processable High-Quality Graphene for Organic Solar Cells
Researchers from MPIP and TU Dresden report the first example of organic solar cells (OSCs) with a solution-processed transparent electrode based on electrochemical exfoliated graphene (EG). Thanks to the high-quality of EG, the fine control of the morphology and uniformity of the film, the OSCs fabricated in this study exhibit improved features compared to other solution-processable graphene-based organic photovoltaic devices up-to-date. Our work is a step forward toward the application of solution-processable high-quality graphene as transparent electrode in solar cells as well as other organic electronics.
© ACS (2017)
Spray coating of solution-processable graphene and the related solar cell performance
Photoswitchable Micro-Supercapacitor Based on a Diarylethene-Graphene Composite Film
Zhaoyang Liu, Hai I. Wang, Akimitsu Narita, Qiang Chen, Zoltan Mics, Dmitry Turchinovich, Mathias Kläui, Mischa Bonn, and Klaus Müllen
Photoswitchable Micro-Supercapacitor Based on a Diarylethene-Graphene Composite Film
Stimuli-responsive micro-supercapacitors (MSCs) controlled by external stimuli can enable a wide range of applications for future on-chip energy storage. Here, we report on a photoswitchable MSC based on a diarylethene-graphene composite film. The microdevice delivers an outstanding and reversible capacitance modulation of up to 20%, demonstrating a prototype photoswitchable MSC. Terahertz spectroscopy indicates that the photoswitching of the capacitance is enabled by the reversible tuning of interfacial charge injection into diarylethene molecular orbitals, as a consequence of charge transfer at the diarylethene–graphene interface upon light modulation.
© ACS (2017)
Schematic illustration of photoresponsive micro-supercapacitor (MSC) device with Diarylethene (DAE) on the top of graphene electrodes.
Lateral Fusion of Chemical Vapor Deposited N = 5 Armchair Graphene Nanoribbons
Zongping Chen, Hai I. Wang, Nerea Bilbao, Joan Teyssandier, Thorsten Prechtl, Nicola Cavani, Alexander Tries, Roberto Biagi, Valentina De Renzi, Xinliang Feng, Mathias Kläui, Steven De Feyter, Mischa Bonn, Akimitsu Narita, and Klaus Müllen
Lateral Fusion of Chemical Vapor Deposited N = 5 Armchair Graphene Nanoribbons
Bottom-up synthesis of low-bandgap graphene nanoribbons with various widths is of great importance for their applications in electronic and optoelectronic devices. Here we demonstrate a synthesis of N = 5 armchair graphene nanoribbons (5-AGNRs) and their lateral fusion into wider AGNRs, by a chemical vapor deposition method. The efficient formation of 10- and 15-AGNRs is revealed by a combination of different spectroscopic methods, including Raman and UV-Vis-near infrared spectroscopy as well as by scanning tunneling microscopy. The degree of fusion and thus the optical and electronic properties of the resulting GNRs can be controlled by the annealing temperature, providing GNR films with optical absorptions up to ~2250 nm.
© ACS (2017)
Left: CVD growth of N = 5 armchair GNRs (5-AGNRs) and their lateral fusion to wider GNRs. Right: Raman spectra of AGNRs annealed at different temperature. The numbers 5, 10, etc. indicate the position of the RBLM peaks of respective AGNRs (excitation wavelength: 785 nm).
Electrochemical TERS Elucidates Potential-Induced Molecular Reorientation of Adenine/Au(111)
Natalia Martín Sabanés, Tatsuhiko Ohto, Denis Andrienko, Yuki Nagata, Katrin F. Domke
Electrochemical TERS Elucidates Potential-Induced Molecular Reorientation of Adenine/Au(111)
Electrochemical surface activity arises from the interaction and geometric arrangement of molecules at electrified interfaces. We present a novel electrochemical tip-enhanced Raman spectroscope that can access the vibrational fingerprint of less than 100 small, non-resonant molecules adsorbed at atomically flat Au electrodes to study their adsorption geometry and chemical reactivity as a function of applied potential. Combining experimental and simulation data for showcase adenine/Au(111), we conclude that protonated physisorbed adenine adapts a tilted orientation at low potentials while it is vertically adsorbed around the potential of zero charge. Further potential increase induces adenine deprotonation and reorientation to a planar configuration. The extension of EC-TERS to the study of adsorbate reorientation significantly broadens the applicability of this advanced spectroelectrochemical tool for the nanoscale characterization of a full range of electrochemical interfaces.
© Wiley VCH (2017)
The potential-induced reorientation and chemical conversion of < 100 molecules at a solid/liquid electrode interface is monitored in situ with help of newly developed electrochemical tip-enhanced Raman spectroscopy.
Main-chain poly(phosphoester)s: History, syntheses, degradation, bio-and flame-retardant applications
Kristin N. Bauer, Hisaschi T. Tee, Maria M. Velencoso, Frederik R. Wurm
Main-chain poly(phosphoester)s: History, syntheses, degradation, bio-and flame-retardant applications
Nature on planet earth needs poly(phosphoester)s (PPEs). They determine life in the form of DNA & RNA, and, as pyrophosphates, they store chemical energy in organisms. Polymer chemistry, however, is dominated by polyolefins and polycarboxylic esters produced on a large scale today. Recent work has illustrated the potential of PPEs for future applications beyond flame-retardancy, the main application of PPEs today, and provided a coherent vision to implement PPEs in modern applications that demand biocompatibility and degradability as well as the possibility to adjust the properties to individual needs. This comprehensive review summarizes synthetic protocols to PPEs, their applications in biomedicine and their flame retardant properties. We highlight recent developments that may make phosphorus-based polymers attractive materials for various future applications.
© MPIP (2017)
A comprehensive review about poly(phosphoester)s
Role of Edge Engineering in Photoconductivity of Graphene Nanoribbons
Ivan Ivanov, Yunbin Hu, Silvio Osella, Uliana Beser, Hai I. Wang, David Beljonne, Akimitsu Narita, Klaus Müllen, Dmitry Turchinovich, and Mischa Bonn
Role of Edge Engineering in Photoconductivity of Graphene Nanoribbons
This collaborative synthetic-spectroscopic-theoretical study of the effect of edge engineering in graphene nanoribbons (GNRs) on their photoconductivity reveals that the variation of the side chains does not alter the photoconductive properties of GNRs, but the edge structure has a strong impact on the carrier mobility in GNRs by affecting the carrier momentum scattering rates. Calculations of the ribbon electronic structure and theoretical transport studies show that phonon scattering plays a significant role in microscopic conduction in GNRs with different edge structures.
© ACS (2017)
The mobility of electrons through nanoribbons depends on the shape of the edges, but not the chemical termination of the edges.
Conical Ionic Amphiphiles Endowed with Micellization Ability but Lacking Air– and Oil–Water Interfacial Activity
Hirohisa Nitta, Koji Harano, Mayuko Isomura, Ellen H.G. Backus, Mischa Bonn, and Eiichi Nakamura
Conical Ionic Amphiphiles Endowed with Micellization Ability but Lacking Air– and Oil–Water Interfacial Activity
In collaboration with the Nakamura group (Tokyo), a new type of amphiphiles is presented that serve as selective "surfactants": they are not surface active at the water-air interface, but they are very active at the solid-water interface. The amphiphiles possess a conical shape consisting of a hydrophobic apex and five ionic termini at its base of the cone. The conical shape and the high charge density cooperatively impede the monolayer formation at the interfaces, and hence prevent foaming and emulsification. On the other hand, the conical shape strongly assists micelle formation in water, and hemimicelle formation on a solid surface to promote dissolution of nanoparticles such as magnetic nanoparticles and nanocarbons in water.
© ACS (2017)
New surfactants are not surface active at the water/air interface, but very active at the water/solid interface.
Ultrafast Delamination of Graphite into High-Quality Graphene Using Alternating Currents
Sheng Yang, Antonio Gaetano Ricciardulli, Shaohua Liu, Renhao Dong, Martin R. Lohe, Alfons Becker, Marco A. Squillaci, Paolo Samorì, Klaus Müllen, Xinliang Feng
Ultrafast Delamination of Graphite into High-Quality Graphene Using Alternating Currents
To bridge the gap between laboratory-scale study and commercial applications, mass production of high quality graphene is essential. Researchers from MPIP, TU Dresden demonstrate a scalable exfoliation strategy towards the production of graphene sheets with excellent yield, great production rate and outstanding electronic property. The high-quality solution-processable exfoliated graphene holds great promise for a wide spectrum of applications, such as inkjet printing, solar cells and composites.
© WILEY-VCH (2017)
Delamination of graphite using alternating currents
Dipolar Molecular Capping in Quantum Dot-Sensitized Oxides: Fermi Level Pinning Precludes Tuning Donor-Acceptor Energetics
Hai I. Wang, Hao Lu, Yuki Nagata, Mischa Bonn, and Enrique Cánovas
Dipolar Molecular Capping in Quantum Dot-Sensitized Oxides: Fermi Level Pinning Precludes Tuning Donor-Acceptor Energetics
Exploiting quantum dot (QD) nanocrystals as sensitizers of mesoporous metal oxides represents a promising path towards low cost solutions for solar energy conversion (e.g. in sensitized solar cells or in photocatalytic H2 generation). After photon absorption in the QD, an exciton is created; this exciton can be dissociated at the QD-oxide interface by a cost of energy that is given primarily by the energy difference between donor-acceptor states (QD LUMO and oxide conduction band). In this respect, reducing the energy offset between donor and acceptor is a necessary requirement for improved photoconversion efficiencies in sensitized architectures. One proposed path for reducing energy losses at QD sensitized interfaces refers to the fine tuning of donor workfunction by exploiting QD dipolar molecular capping treatments. However, previous attempts revealed a very modest gain in device efficieny induced by these treatments. In this contribution we rationalize these observations by demonstrating that Fermi level pinning at the strongly coupled QD-oxide interfaces precludes tuning donor-acceptor energetics by dipolar molecular capping. These results highlight that reducing photoconversion losses at QD sensitized interfaces by dipolar treatments will requires decoupling between the donating and accepting states (e.g. by introducing an insulating layer in bettwen QD and oxide).
© Enrique Cánovas (2017)
Can we tune interfacial electron transfer in quantum dot sensitized oxides by dipolar capping?
Single-crystal Ih ice surface: Connecting macroscopic etch pits and molecular structure
Alexandra Brumberg, Kevin D. Hammonds, Ian Baker, Ellen H. G. Backus, Patrick J. Bisson, Mischa Bonn, Charles Daghlian, Markus Mezger, Mary Jane Shultz
Single-crystal Ih ice surface: Connecting macroscopic etch pits and molecular structure
Physics and chemistry of ice surfaces are not only of fundamental interest but also have important impacts on biological and environmental processes. It is well known that the microscopic structure of the ubiquitous hexagonal ice crystal consists of stacked layers of chair-form hexagonal rings, referred to as molecular hexagons. Crystallographic unit cells can be assembled into a regular right hexagonal prism. The bases are labeled crystallographic hexagons. The molecular and crystallographic hexagons are rotated 30° relative to each other. The connection between the familiar macroscopic shape of hexagonal snowflakes and either of the hexagons is not obvious per se. Direct comparison of etch pit images, reporting on the macroscopic shape, and the electron backscatter diffraction results, providing the microscopic structure, compellingly connects the macroscopic etch pit (or: snowflake) hexagon to the crystallographic, and not molecular, hexagon.
© MPI-P (2017)
From where does the snow flake get its form? Connecting macroscopic etch pits and molecular structure of single-crystal hexagonal ice.
Photocatalytically Active Lubricant-Impregnated Surface
Sanghyuk Wooh and Hans-Jürgen Butt
Photocatalytically Active Lubricant-Impregnated Surface
We designed a new lubricant-impregnated surface which possesses photocatalytic activity as well as improved liquid repellency. This photocatalytically active lubricant-impregnated surface (PALIS) was fabricated by simple polydimethylsiloxane (PDMS) brush grafting reaction via illumination. Liquid drops slide on the PALIS by the PDMS lubricant swelled PDMS brush layer. By the combination effect of photocatalytic activity and liquid-repellency, the PALIS exhibits enhanced self-cleaning property for both dusts and organic contaminations.
© WILEY-VCH (2017)
The photocatalytically active lubricant-impregnated surface was introduced by PDMS grafting reaction on mesoporous metal-oxide photocatalysts.
Heteroatom-Doped Perihexacene from a Double Helicene Precursor: On-Surface Synthesis and Properties
Xiao-Ye Wang, Thomas Dienel, Marco Di Giovannantonio, Gabriela Borin Barin, Neerav Kharche, Okan Deniz, José I. Urgel, Roland Widmer, Samuel Stolz, Luis Henrique De Lima, Matthias Muntwiler, Matteo Tommasini, Vincent Meunier, Pascal Ruffieux, Xinliang Feng, Roman Fasel, Klaus Müllen, and Akimitsu Narita
Heteroatom-Doped Perihexacene from a Double Helicene Precursor: On-Surface Synthesis and Properties
Periacenes, which comprise two laterally peri-fused linear acenes, are an important class of zigzag-edged nanographene molecules with intriguing electronic and magnetic properties. However, the synthesis of periacenes, especially peritetracene and higher homologues, has been severely hampered by their poor stability. Herein, we report the surface-assisted synthesis of the hitherto longest periacene analogue with oxygen-boron-oxygen (OBO) segments on the zigzag edges, that is, a heteroatom-doped perihexacene. The structure was clearly visualized by scanning tunneling microscopy and noncontact atomic force microscopy. X-ray photoelectron spectroscopy and Raman spectroscopy on both the precursor and the perihexacene analogue provided further insights into the cyclodehydrogenation process. It is found that the conformation of the double helicene is highly influenced by the metal surface and the self-assembly structures. Furthermore, both the precursor and the perihexacene analogue form one-dimensional superstructures on surfaces by virtue of OBO units. The intermolecular interactions resulted from OBO segments indicate great potential for fabricating tailor-made graphene nanoarchitectures in the future.
© JACS (2017)
Heteroatom-Doped Perihexacene from a Double Helicene Precursor
Nanoparticle amount, and not size, determines chain alignment and nonlinear hardening in polymer nanocomposites
H. Samet Varol, Fanlong Meng, Babak Hosseinkhani, Christian Malm, Daniel Bonn, Mischa Bonn, Alessio Zaccone, and Sapun H. Parekh
Nanoparticle amount, and not size, determines chain alignment and nonlinear hardening in polymer nanocomposites
Polymer nanocomposites—materials in which a polymer matrix is blended with nanoparticles (or fillers)—strengthen under sufficiently large strains. Such strain hardening is critical to their function, especially for materials that bear large cyclic loads such as car tires or bearing sealants. Although the reinforcement (i.e., the increase in the linear elasticity) by the addition of filler particles is phenomenologically understood, considerably less is known about strain hardening (the nonlinear elasticity). Here, we elucidate the molecular origin of strain hardening using uniaxial tensile loading, microspectroscopy of polymer chain alignment, and theory. The strain-hardening behavior and chain alignment are found to depend on the volume fraction, but not on the size of nanofillers. This contrasts with reinforcement, which depends on both volume fraction and size of nanofillers, potentially allowing linear and nonlinear elasticity of nanocomposites to be tuned independently.
© Hasan Samet Varol (2017)
Strain hardening in polymer nanocomposites is a function of inorganic “filler” particle amount and surprisingly independent of filler size. A cancellation of filler size effects is observed because of inter-particle polymer chain alignment.
Mitochondria Targeted Protein-Ruthenium Photosensitizer for Efficient Photodynamic Applications
Sabyasachi Chakrabortty, Bikram Keshari Agrawalla, Anne Stumper, Naidu M Vegi, Stephan Fischer, Christian Reichardt, Michael Kögler, Benjamin Dietzek, Michaela Feuring-Buske, Christian Buske, Sven Rau, and Tanja Weil
Mitochondria Targeted Protein-Ruthenium Photosensitizer for Efficient Photodynamic Applications
Organelle-targeted photosensitization represents a promising approach in photodynamic therapy where the design of the active photosensitizer (PS) is very crucial. In this work, we developed a macromolecular PS with multiple copies of mitochondria-targeting groups and ruthenium complexes that displays highest phototoxicity toward several cancerous cell lines. In particular, enhanced anticancer activity was demonstrated in acute myeloid leukemia cell lines, where significant impairment of proliferation and clonogenicity occurs. Finally, attractive two-photon absorbing properties further underlined the great significance of this PS for mitochondria targeted PDT applications in deep tissue cancer therapy.
© American Chemical Society (2017)
A novel plasma protein based phototoxic, biodegradable, mitochondria targeted macromolecular photosensitizer showing significantly enhanced photodynamic behavior
The Cassie-Wenzel transition of fluids on nanostructured substrates: Macroscopic force balance versus microscopic density-functional theory
Nikita Tretyakov, Periklis Papadopoulos, Doris Vollmer, Hans-Jürgen Butt, Burkhard Dünweg und Kostas Daoulas
The Cassie-Wenzel transition of fluids on nanostructured substrates: Macroscopic force balance versus microscopic density-functional theory
Classical density functional theory is applied to investigate the validity of a phenomenological force-balance description of the stability of the Cassie state of liquids on substrates with nanoscale corrugation. A bulk free-energy functional of third order in local density is combined with a square-gradient term, describing the liquid-vapor interface. The bulk free energy is parameterized to reproduce the liquid density and the compressibility of water. The square-gradient term is adjusted to model the width of the water-vapor interface. The substrate is modeled by an external potential, based upon the Lennard-Jones interactions. The three-dimensional calculation focuses on substrates patterned with nanostripes and square-shaped nanopillars. Using both the force-balance relation and density-functional theory, we locate the Cassie-to-Wenzel transition as a function of the corrugation parameters. We demonstrate that the force-balance relation gives a qualitatively reasonable description of the transition even on the nanoscale. The force balance utilizes an effective contact angle between the fluid and the vertical wall of the corrugation to parameterize the impalement pressure. This effective angle is found to have values smaller than the Young contact angle. This observation corresponds to an impalement pressure that is smaller than the value predicted by macroscopic theory. Therefore, this effective angle embodies effects specific to nanoscopically corrugated surfaces, including the finite range of the liquid-solid potential (which has both repulsive and attractive parts), line tension, and the finite interface thickness. Consistently with this picture, both patterns (stripes and pillars) yield the same effective contact angles for large periods of corrugation.
© AIP Publishing (2017)
The Cassie-to-Wenzel transition is located for striped (left) and pillared (right) substrates as a function of the corrugation parameters a and cx. Parts of the corrugations re-enter the calculation box through periodic boundary conditions.
Periodic potentials in hybrid van der Waals heterostructures formed by supramolecular lattices on graphene
Marco Gobbi, Sara Bonacchi, Jian X. Lian, Yi Liu, Xiao-YeWang, Marc-Antoine Stoeckel, Marco A. Squillaci, Gabriele D’Avino, Akimitsu Narita, Klaus Müllen, Xinliang Feng, Yoann Olivier, David Beljonne, Paolo Samorì & Emanuele Orgiu
Periodic potentials in hybrid van der Waals heterostructures formed by supramolecular lattices on graphene
The rise of 2D materials made it possible to form heterostructures held together by weak interplanar van der Waals interactions. Within such van der Waals heterostructures, the occurrence of 2D periodic potentials significantly modifies the electronic structure of single sheets within the stack, therefore modulating the material properties. However, these periodic potentials are determined by the mechanical alignment of adjacent 2D materials, which is cumbersome and time-consuming. Here we show that programmable 1D periodic potentials extending over areas exceeding 104 nm2 and stable at ambient conditions arise when graphene is covered by a self-assembled supramolecular lattice. The amplitude and sign of the potential can be modified without altering its periodicity by employing photoreactive molecules or their reaction products. In this regard, the supramolecular lattice/graphene bilayer represents the hybrid analogue of fully inorganic van der Waals heterostructures, highlighting the rich prospects that molecular design offers to create ad hoc materials.
© Macmillan Publishers Limited (2017)
Calculated differential electrical potential induced by a self-assembled supramolecular lattice on graphene. The supramolecular lattice is superimposed for clarity. The electrical potential is periodically modulated, with negative values in the region below the molecular heads. Carbon atoms are shown in grey, hydrogen in white, nitrogen in red, fluorine in light blue and chlorine in green.
Stable Hydrophobic Metal-Oxide Photocatalysts via Grafting Polydimethylsiloxane Brush
Sanghyuk Wooh, Noemí Encinas, Doris Vollmer, and Hans-Jürgen Butt
Stable Hydrophobic Metal-Oxide Photocatalysts via Grafting Polydimethylsiloxane Brush
We designed a new method for grafting polydimethylsiloxane (PDMS) on surfaces of metal-oxide photocatalysts via simple illumination. By this PDMS grating reaction, stable photocatalytically active liquid-repellent surfaces were realized. The PDMS grafted metal-oxide photocatalysts exhibited improved self-cleaning and anti-biofouling properties by the combination effect of photocatalytic activity and liquid-repellency.
© WILEY-VCH (2017)
The photocatalytically active liquid-repellent surfaces were introduced by developing PDMS grafting reaction on metal-oxide photocatalysts.
Structure–Property Relations of Methylamine Vapor Treated Hybrid Perovskite CH3NH3PbI3 Films and Solar Cells
Bert Conings, Simon A. Bretschneider, Aslihan Babayigit, Nicolas Gauquelin, Ilaria Cardinaletti, Jean Manca, Jo Verbeeck, Henry J Snaith, Hans-Gerd Boyen
Structure–Property Relations of Methylamine Vapor Treated Hybrid Perovskite CH3NH3PbI3 Films and Solar Cells
The power conversion efficiency of halide perovskite solar cells is heavily dependent on the perovskite layer being sufficiently smooth and pinhole-free. It has been shown that these features can be obtained even when starting out from rough and discontinuous perovskite film by briefly exposing the film to methylamine (MA) vapor. The exact underlying physical mechanisms of this phenomenon are, however, still unclear. By investigating smooth, MA treated films based on very rough and discontinuous reference films of methylammonium triiode (MAPbI3) and considering their morphology, crystalline features, local conductive properties, and charge carrier lifetime, we unraveled the relation between their characteristic physical qualities and their performance in corresponding solar cells. We discovered that the extensive improvement in photovoltaic performance upon MA treatment is a consequence of the induced morphological enhancement of the perovskite layer together with improved electron injection into TiO2, which in fact compensates for an otherwise compromised bulk electronic quality simultaneously caused by the MA treatment.
© American Chemical Society (2017)
Methylamine treatment of sensitized perovskite solar cells facilitates the infiltration of the perovskite into the TiO2 and evens out the perovskite capping layer to reduce shunting, resulting in a dramatic improvement of the efficiency.
Shape Controlled Hierarchical Porous Hydrophobic/Oleophilic Metal-Organic Nanofibrous Gel Composites for Oil Adsorption
Kolleboyina Jayaramulu, Florian Geyer, Martin Petr, Radek Zboril, Doris Vollmer, Roland A. Fischer
Shape Controlled Hierarchical Porous Hydrophobic/Oleophilic Metal-Organic Nanofibrous Gel Composites for Oil Adsorption
We designed a simple route to synthesize hydrophobic and superoleophilic, fibrous hierarchically porous hybrid materials composed of metal organic gels (MOGs) with fluorinated graphene oxide (FGO). The integration of FGO layer stacks to light MOGs has proven a great asset in combining functional features and enhancement of materials performance.
© Advanced Materials (2017)
Schematic illustration of the formation of FGO@MOG (top). Coordination perturbation, selective functionalization of MOF-nanoparticles with FGO yields a hybrid composite gel. Water drop (6 µL) on pressed FGO@MOG tablet (bottom left). Oil is adsorbed by the composite material (bottom right).
On-Surface Synthesis and Characterization of 9-Atom Wide Armchair Graphene Nanoribbons
Leopold Talirz, Hajo Söde, Tim Dumslaff, Shiyong Wang, Juan Ramon Sanchez-Valencia, Jia Liu, Prashant Shinde, Carlo A. Pignedoli, Liangbo Liang, Vincent Meunier, Nicholas C. Plumb, Ming Shi, Xinliang Feng, Akimitsu Narita, Klaus Müllen, Roman Fasel, Pascal Ruffieux
On-Surface Synthesis and Characterization of 9-Atom Wide Armchair Graphene Nanoribbons
We present the synthesis of 9-atom-wide armchair-edge GNRs (9-AGNRs) via surface-assisted aryl-aryl coupling and cyclodehydrogenation of a small halogen-substituted precursor molecule on Au(111). In this approach, the molecular precursor precisely defines the width and edge structure of the resulting GNRs down to the single atom, thus providing ultimate control over the band gap by design. We have designed and synthesize suitable monomer with an o-terphenyl-based structure, which selectively provided atomically precise 9-AGNRs as revealed by scanning probe microscopy and Raman spectroscopy. In line with theoretical predictions of their electronic properties, a low band gap of 1.4 eV and small effective masses of 0.1 me for electrons and holes are found for the metal-adsorbed 9-AGNRs, making them an interesting material for room-temperature electronic and optoelectronic switching devices
© American Chemical Society (2017)
High-resolution nc-AFM frequency shift image of 9-AGNR using a CO-functionalized tip with oscillation amplitude of 70 pm (scale bar: 1 nm).
Small Activity Differences Drive Phase Separation in Active-Passive Polymer Mixtures
Jan Smrek and Kurt Kremer
Small Activity Differences Drive Phase Separation in Active-Passive Polymer Mixtures
Recent theoretical studies found that mixtures of active and passive colloidal particles phase separate but only at very high activity ratio. The high value poses serious obstacles for experimental exploration of this phenomenon. Here we show using simulations that when the active and passive particles are polymers, the critical activity ratio decreases with the polymer length. This not only facilitates the experiments but also has implications on the DNA organization in living cell nuclei. Entropy production can be used as an accurate indicator of this nonequilibrium phase transition.
© Jan Smrek and Kurt Kremer (2017)
An initial mixture (left) of active (black) and inactive (yellow) chains spontaneously phase separates into steady state composed of active and passive phases (right).
50th Anniversary Perspective: The Importance of NMR Spectroscopy to Macromolecular Science
Hans Wolfgang Spiess
50th Anniversary Perspective: The Importance of NMR Spectroscopy to Macromolecular Science
This invited Perspective Article for the 50th Anniversary Issue of Macromolecules describes the remarkable development of NMR spectroscopy during the past 50 years with emphasis on applications in macromolecular science. The article cites colleagues from academia and industry, who refer to NMR as a ‘premier technique for polymer studies’. The Max Planck Institute for Polymer Research has significantly contributed to this development. Today NMR spectroscopy is as vibrant as ever and recent advances allow the study of more and more complex molecular as well as materials problems.
© ACS (2017)
During the last 50 years NMR spectroscopy has undergone an unprecedented development as described in the Perspective Article entitled “The Importance of NMR Spectroscopy to Macromolecular Science”.
Directional elastic wave propagation in high-aspect-ratio photoresist gratings: liquid infiltration and aging
E. Alonso-Redondo, A. Gueddida, J. Li, B. Graczykowski, C. M. Sotomayor Torres, Y. Pennec, S. Yang, B. Djafari-Rouhani and G. Fytas
Directional elastic wave propagation in high-aspect-ratio photoresist gratings: liquid infiltration and aging
The vibrational modes in periodic high aspect-ratio nanowalls, assessed by Brillouin light scattering and finite element method calculations, reveal quantitative and qualitative differences with low aspect-ratio nanolines. These are attributed to the two-beam interference lithography fabrication and aging effects. The phononic behavior is drastically altered by changing the environment of the nanowalls, from a unidirectional guiding to an anisotropic propagation along two orthogonal directions in the liquid-infiltrated grating.
© Elena Alonso-Redondo (2017)
Hypersonic phonons guided along high-aspect-ratio nanowalls are enabled to cross the polymeric grating upon liquid infiltration. The phononic band structure is recorded by Brillouin scattering.
Enhancing CO2 Capture using Robust Superomniphobic Membranes
Florian Geyer, Clarissa Schönecker, Hans-Jürgen Butt, Doris Vollmer
Enhancing CO2 Capture using Robust Superomniphobic Membranes
Superomniphobic membranes for post-combustion CO2 capture are introduced. Concentrated aqueous amine solutions stay on the topmost part of the membranes, providing a large liquid/CO2 interface. Wetting of the membrane, which reduces the capture efficiency, is prevented. The CO2 capture rates using the chemically, mechanically, and thermally stable superomniphobic membranes are enhanced by up to 40% relative to commercial membranes.
© WILEY-VCH (2017)
Photograph of 15 µL water, MDEA (20 and 50 wt%) and hexadecane drops on superomniphobic membrane (top) and schematic of the exchange chamber with a superomniphobic membrane (bottom).
Enhanced Crystal Growth in Binary Lennard-Jones Mixtures
M. Radu and K. Kremer
Enhanced Crystal Growth in Binary Lennard-Jones Mixtures
We study the crystal growth in binary Lennard-Jones mixtures by molecular dynamics simulations. Growth dynamics, the structure of the liquid-solid interfaces as well as droplet incorporation into the crystal vary with solution properties. For demixed systems we observe a strongly enhanced crystal growth at the cost of enclosed impurities. Furthermore, we find different interface morphologies depending on solubility. We relate our observations to growth mechanisms based on the Gibbs-Thomson effect as well as to predictions of the Kardar-Parisi-Zhang theory in 2+1 dimensions.
© American Physical Society (2017)
Simulations of enhanced crystal growth in binary Lennard-Jones mixtures: two particle species in a liquid state are shown in black and light grey, while crystalline particles of are dark green for FCC- and orange for HCP-like structures.
Coating nanoparticles with tunable surfactants facilitates control over the protein corona
J. Müller, K. N. Bauer, D. Prozeller, J. Simon, V. Mailänder, F. R. Wurm, S. Winzen, K. Landfester
Coating nanoparticles with tunable surfactants facilitates control over the protein corona
Nanoparticles with long blood circulation time are a prerequisite for targeted drug delivery. To make the nanoparticles invisible for phagocytizing cells, functional moieties on the particle surface are believed to be necessary to attract specific so-called ‘stealth’ proteins forming a protein ‘corona’. Currently, covalent attachment of those moieties represents the only way to achieve that attraction. However, that approach requires a high synthetic effort and is difficult to control. Therefore, we present the coating of model nanoparticles with biodegradable polymeric surfactants as an alternative method. The thermodynamic parameters of the coating process can be tuned by adjusting the surfactants' block lengths and hydrophilicity. Consequently, the unspecific protein adsorption and aggregation tendency of the particles can be controlled, and stealth proteins inhibiting cell uptake are enriched on their surface. This non-covalent approach could be applied to any particle type and thus facilitates tuning the protein corona and its biological impact.
© Elsevier (2017)
Specifically tailored polyphosphoester based surfactants cover the surface of nanomaterials and thus change the thermodynamic properties of following protein adsorption processes
An amphiphilic ruthenium polymetallodrug for combined photodynamic therapy and photochemotherapy in vivo
Wen Sun, Shuyi Li, Bernhard Häupler, Juan Liu, Shubin Jin, Werner Steffen, Ulrich S. Schubert, Hans-Jürgen Butt, Xing-Jie Liang, Si Wu
An amphiphilic ruthenium polymetallodrug for combined photodynamic therapy and photochemotherapy in vivo
An amphiphilic Ru-containing block copolymer self-assembles into nanoparticles. These nanoparticles accumulate at the tumor sit. Red light irradiation of the block copolymer nanoparticles releases anticancer Ru complexes and generates cytotoxic 1O2, both of which can inhibit tumor growth.
© Wiley (2017)
An amphiphilic Ru-containing polymetallodrug was used for anticancer phototherapy
IL-2 functionalized nanocapsules for T cell-based immunotherapy
S.U. Frick, M.P. Domogalla, G. Baier, F.R. Wurm, V. Mailänder, K. Landfester, K. Steinbrink
IL-2 functionalized nanocapsules for T cell-based immunotherapy
Targeting of T cells for biomedical applications still remains an obstacle as they disclose reduced endocytic activities. Here, by coupling the cytokine interleukin-2 (IL-2) to the surface of hydroxyethyl starch nanocapsules, scientists of the MPI-P and the University Medical Center Mainz demonstrated a direct and specific T cell targeting in vitro and in vivo by IL-2 receptor mediated internalization.
© MPI-P (2017)
By coupling the cytokine interleukin-2 to the surface of hydroxyethylstarch nanocapsules, a direct and specific T cell targeting in vitro and in vivo by receptor mediated internalization can be achieved.