Liquid-Crystalline Elastomer-Nanoparticle Hybrids with Reversible Switch of Magnetic Memory

Johannes M. Haberl¹, Antoni Sánchez-Ferrer¹, Adriana M. Mihut^2,†, Hervé Dietsch^2,‡, Ann M. Hirt³, Raffaele Mezzenga^1,*

A stimuli-responsive material is synthesized that combines the actuation potential of liquid-crystalline elastomers with the anisotropic magnetic properties of ellipsoidal iron oxide nanoparticles. The resulting nanocomposite exhibits unique shape-memory features with magnetic information, which can be reversibly stored and erased via parameters typical of soft materials, such as high deformations, low stresses, and liquid-crystalline smectic-isotropic transition temperatures.

Triggering Cell Adhesion, Migration or Shape Change with a Dynamic Surface Coating

Stijn F. M. van Dongen^1,*, Paolo Maiuri², Emmanuelle Marie¹, Christophe Tribet¹, Matthieu Piel^2,*

 There's an APP for that: cell-repellent APP (azido-[polylysine-g-PEG]) is used to create substrates for spatially controlled dynamic cell adhesion. The simple addition of a functional peptide to the culture medium rapidly triggers cell adhesion. This highly accessible yet powerful technique allows diverse applications, demonstrated through tissue motility assays, patterned coculturing and triggered cell shape change

Self-Healing Stretchable Wires for Reconfigurable Circuit Wiring and 3D Microfluidics

Etienne Palleau¹, Stephen Reece¹, Sharvil C. Desai¹, Michael E. Smith², Michael D. Dickey^1,*

 

This article describes the fabrication of self-healing stretchable wires formed by embedding liquid metal wires in microchannels composed of self-healing polymer. These stretchable wires can be completely severed with scissors and rapidly self-heal both mechanically and electrically at ambient conditions. By cutting the channels strategically, the pieces can be re-assembled in a different order to form complex microfluidic networks in 2D or 3D space.

Decoupling Cell and Matrix Mechanics in Engineered Microtissues Using Magnetically Actuated Microcantilevers

Ruogang Zhao¹, Thomas Boudou², Wei-Gang Wang¹, Christopher S. Chen^2,*, Daniel H. Reich^1,*

A novel bio-magnetomechanical microtissue system is described for magnetic actuation of arrays of 3D microtissues using microcantilevers. This system enables both in situ measurements of fundamental mechanical properties of engineered tissue, such as contractility and stiffness, as well as dynamic stimulation of the microtissues. Using this system, cell and extracellular matrix contributions to the tissue mechanical properties are decoupled for the first time under both static and dynamic loading conditions.

Highly Conductive and Strain-Released Hybrid Multilayer Ge/Ti Nanomembranes with Enhanced Lithium-Ion-Storage Capability

Chenglin Yan^1,*, Wang Xi^1,*, Wenping Si^1,2, Junwen Deng^1,2, Oliver G. Schmidt^1,2

Highly conductive and hybridized microtubes relying on strain-released ultrathin Ti/Ge bilayer nanomembranes are reported. These hybrid multilayer microtubes show a remarkably enhanced reversible capacity up to 1495 mA h g⁻¹ with a high first-cycle Coulombic efficiency of 85%, and demonstrate an excellent capacity of ≈930 mA h g⁻¹ after 100 cycles.

Thiophene-Fused Bisdehydro[12]annulene That Undergoes Transannular Alkyne Cycloaddition by Either Light or Heat

Aiko Fukazawa *†, Hiroya Oshima †, Yoshihito Shiota #, Shouya Takahashi #, Kazunari Yoshizawa *#, and Shigehiro Yamaguchi *†‡§

A new bisdehydro[12]annulene derivative having a thiophene-fused structure has been synthesized. This highly twisted π-conjugated macrocycle with two acetylene moieties in close proximity produces a [2+2]-type alkyne cycloadduct by either photoirradiation or mild heating without any transition metals. Theoretical calculations reveal that the thermal reaction proceeds through successive 8π and 4π electrocyclic reactions, while the photochemical reaction is an asynchronous concerted [2+2] cycloaddition. The fused structure with the less-aromatic thiophene ring is crucial for achieving this reaction. The cycloadduct, thiophene-fused biphenylene, has significant potential as a new polycyclic π-scaffold for electronic applications.

Droplet microfluidics driven by gradients of confinement

Rémi Dangla, S. Cagri Kayi, and Charles N. Baroud¹

The miniaturization of droplet manipulation methods has led to drops being proposed as microreactors in many applications of biology and chemistry. In parallel, microfluidic methods have been applied to generate monodisperse emulsions for applications in the pharmaceuticals, cosmetics, and food industries. To date, microfluidic droplet production has been dominated by a few designs that use hydrodynamic forces, resulting from the flowing fluids, to break drops at a junction. Here we present a platform for droplet generation and manipulation that does not depend on the fluid flows. Instead, we use devices that incorporate height variations to subject the immiscible interfaces to gradients of confinement. The resulting curvature imbalance along the interface causes the detachment of monodisperse droplets, without the need for a flow of the external phase. Once detached, the drops are self-propelled due to the gradient of surface energy. We show that the size of the drops is determined by the device geometry; it is insensitive to the physical fluid properties and depends very weakly on the flow rate of the dispersed phase. This allows us to propose a geometric theoretical model that predicts the dependence of droplet size on the geometric parameters, which is in agreement with experimental measurements. The approach presented here can be applied in a wide range of standard applications, while simplifying the device operations. We demonstrate examples for single-droplet operations and high-throughput generation of emulsions, all of which are performed in simple and inexpensive devices.

One-Pot versus Sequential Reactions in the Self-Assembly of Gigantic Nanoscale Polyoxotungstates

Jing Gao , Jun Yan , Sebastian Beeg , De-Liang Long *, and Leroy Cronin *

By using a new type of lacunary tungstoselenite {Se2W29O103} (1), which contains a “defect” pentagonal {W(W)4} unit, we explored the assembly of clusters using this building block and demonstrate how this unit can give rise to gigantic nanomolecular species, using both a “one-pot” and “stepwise” synthetic assembly approach. Specifically, exploration of the one-pot synthetic parameter space lead to the discovery of {Co2.5(W3.5O14)(SeW9O33)(Se2W30O107)} (2), {CoWO(H2O)3(Se2W26O85)(Se3W30O107)2} (3), and {Ni2W2O2Cl(H2O)3(Se2W29O103) (Se3W30O107)2} (4), effectively demonstrating the potential of the {Se2W29} based building blocks, which was further extended by the isolation of a range of 3d transition metal doped tetramer family derivatives: {M2WnOm(H2O)m(Se2W29O102)4} (M = Mn, Co, Ni or Zn, n = 2, m = 4; M = Cu, n = 3, m = 5) (5 - 9). To contrast the ‘one-pot’ approach, an optimized stepwise self-assembly investigation utilizing 1 as a precursor was performed showing that the high nuclearity clusters can condense in a more controllable way allowing the tetrameric clusters (5 - 8) to be synthesized with higher yield, but it was also shown that 1 can be used to construct a gigantic {W174} hexameric-cluster {Cu9Cl3(H2O)18(Se2W29O102)6} (10). Further, 1 can also dimerize to {(Se2W30O105)2} (11) by addition of extra tungstate under similar conditions. All the clusters were characterized by single-crystal X-ray crystallography, chemical analysis, infrared spectroscopy, thermogravimetric analysis, and electrospray ionization mass spectrometry, which remarkably showed that all the clusters, even the largest cluster, 10 ( 50 kD), could be observed as the intact cluster demonstrating the extraordinary potential of this approach to construct robust gigantic nanoscale polyoxotungstates.

The Li-Ion Rechargeable Battery: A Perspective

John B. Goodenough * and Kyu-Sung Park

Each cell of a battery stores electrical energy as chemical energy in two electrodes, a reductant (anode) and an oxidant (cathode), separated by an electrolyte that transfers the ionic component of the chemical reaction inside the cell and forces the electronic component outside the battery. The output on discharge is an external electronic current I at a voltage V for a time Δt. The chemical reaction of a rechargeable battery must be reversible on the application of a charging I and V. Critical parameters of a rechargeable battery are safety, density of energy that can be stored at a specific power input and retrieved at a specific power output, cycle and shelf life, storage efficiency, and cost of fabrication. Conventional ambient-temperature rechargeable batteries have solid electrodes and a liquid electrolyte. The positive electrode (cathode) consists of a host framework into which the mobile (working) cation is inserted reversibly over a finite solid–solution range. The solid–solution range, which is reduced at higher current by the rate of transfer of the working ion across electrode/electrolyte interfaces and within a host, limits the amount of charge per electrode formula unit that can be transferred over the time Δt = Δt(I). Moreover, the difference between energies of the LUMO and the HOMO of the electrolyte, i.e., electrolyte window, determines the maximum voltage for a long shelf and cycle life. The maximum stable voltage with an aqueous electrolyte is 1.5 V; the Li-ion rechargeable battery uses an organic electrolyte with a larger window, which increase the density of stored energy for a given Δt. Anode or cathode electrochemical potentials outside the electrolyte window can increase V, but they require formation of a passivating surface layer that must be permeable to Li⁺ and capable of adapting rapidly to the changing electrode surface area as the electrode changes volume during cycling. A passivating surface layer adds to the impedance of the Li⁺ transfer across the electrode/electrolyte interface and lowers the cycle life of a battery cell. Moreover, formation of a passivation layer on the anode robs Li from the cathode irreversibly on an initial charge, further lowering the reversible Δt. These problems plus the cost of quality control of manufacturing plague development of Li-ion rechargeable batteries that can compete with the internal combustion engine for powering electric cars and that can provide the needed low-cost storage of electrical energy generated by renewable wind and/or solar energy. Chemists are contributing to incremental improvements of the conventional strategy by investigating and controlling electrode passivation layers, improving the rate of Li⁺ transfer across electrode/electrolyte interfaces, identifying electrolytes with larger windows while retaining a Li⁺ conductivity σ_Li > 10^–3 S cm^–1, synthesizing electrode morphologies that reduce the size of the active particles while pinning them on current collectors of large surface area accessible by the electrolyte, lowering the cost of cell fabrication, designing displacement-reaction anodes of higher capacity that allow a safe, fast charge, and designing alternative cathode hosts. However, new strategies are needed for batteries that go beyond powering hand-held devices, such as using electrode hosts with two-electron redox centers; replacing the cathode hosts by materials that undergo displacement reactions (e.g. sulfur) by liquid cathodes that may contain flow-through redox molecules, or by catalysts for air cathodes; and developing a Li⁺ solid electrolyte separator membrane that allows an organic and aqueous liquid electrolyte on the anode and cathode sides, respectively. Opportunities exist for the chemist to bring together oxide and polymer or graphene chemistry in imaginative morphologies.

Microfluidic fabrication of photo-responsive hydrogel capsules

Abstract: We report thermo- and photo-responsive hydrogel capsules, providing controlled encapsulation and triggered release of water-soluble encapsulants. Monodisperse O/W/O (oil-in-water-in-oil) double-emulsion drops are produced in a capillary microfluidic device as templates, which transform into hydrogel capsules upon polymerization of thermo-sensitive monomers in water phase containing gold nanorods.

This is an interesting work on Chem. Com. focusing on a encapsulation and controlled release manipulating microfluidic systems. More specifically, a double emulsion droplet (Oil/Water/Oil) was produced in the microfluidic tubes. Thermally responsive monomer was included in the middle layer, and eventually functions upon heat treatment releasing encapsulated drugs. They also embedded gold nanorods and fluorescent dyes for better characterization. Meanwhile, the gold nanorods response to radiative activation bring the rupture of capsules as a result.

General Methodology of Using Oil-in-Water and Water-in-Oil Emulsions for Coiling Nanofilaments

General Methodology of Using Oil-in-Water and Water-in-Oil Emulsions for Coiling Nanofilaments

Liyong Chen †, Suzhu Yu ‡, Hong Wang †, Jun Xu †,Cuicui Liu †, Wen Han Chong †, and Hongyu Chen *†

Abstract: Hydrophobic carbon nanotubes (CNTs) and hydrophilic nanofilaments such as oxidized CNTs, Pd nanowires (NWs), and MnO₂ NWs are transformed from wires to rings by a general methodology. We show that both oil-in-water and water-in-oil emulsions, so long as their droplet size is sufficiently small, can exert significant force to the entrapped nanostructures, causing their deformation. This effect can be easily achieved by simply mixing a few solutions in correct ratios. Even preformed oil droplets can take in CNTs from the aqueous solution converting them into rings, indicating the important role of thermodynamics: The question here is not if the droplets can exert sufficient force to bend the nanofilaments, because their random vibration may be already doing it. As long as the difference in solvation energy is large enough for a nanofilament, it would “want” to move away from the bulk solution and fit inside tiny droplets, even at the cost of induced strain energy. That said, the specific interactions between a droplet and a filament are also of importance. For example, when an oil droplet rapidly shrinks in size, it can compress the entrapped CNTs in multiple stages into structures with higher curvatures (thus higher strain) than that of a circular ring, which has minimal induced strain inside a spherical droplet.

This work could be useful for work in forming nanoscale structures through self-assembly or interfacial aspects. They give a lot of consideration to the mechanism of the process, so it should be possible to extrapolate principles to related work.

Bioinspired Surfaces with Dynamic Topography for Active Control of Biofouling

Phanindhar Shivapooja^1,†, Qiming Wang^2,†, Beatriz Orihuela³, Daniel Rittschof³, Gabriel P. López^1,2,4,*, Xuanhe Zhao^2,4,*

Dynamic change of surface area and topology of elastomers is used as a general, environmentally friendly approach for effectively detaching micro- and macro-fouling organisms adhered on the elastomer surfaces. Deformation of elastomer surfaces under electrical or pneumatic actuation can debond various biofilms and barnacles. The bio-inspired dynamic surfaces can be fabricated over large areas through simple and practical processes. This new mechanism is complementary with existing materials and methods for biofouling control.

Superomniphobic Surfaces for Effective Chemical Shielding

Shuaijun Pan †, Arun K. Kota †, Joseph M. Mabry , and Anish Tuteja *†§

Superomniphobic surfaces display contact angles >150° and low contact angle hysteresis with essentially all contacting liquids. In this work, we report surfaces that display superomniphobicity with a range of different non-Newtonian liquids, in addition to superomniphobicity with a wide range of Newtonian liquids. Our surfaces possess hierarchical scales of re-entrant texture that significantly reduce the solid–liquid contact area. Virtually all liquids including concentrated organic and inorganic acids, bases, and solvents, as well as viscoelastic polymer solutions, can easily roll off and bounce on our surfaces. Consequently, they serve as effective chemical shields against virtually all liquids—organic or inorganic, polar or nonpolar, Newtonian or non-Newtonian.

Degradable Terpolymers with Alkyl Side Chains Demonstrate Enhanced Gene Delivery Potency and Nanoparticle Stability

Ahmed A. Eltoukhy¹, Delai Chen^2,3, Christopher A. Alabi², Robert Langer^1,2,4, Daniel G. Anderson^2,4,*

Degradable, cationic poly(β-amino ester)s (PBAEs) with alkyl side chains are developed for non-viral gene delivery. Nanoparticles formed from these PBAE terpolymers exhibit significantly enhanced DNA transfection potency and resistance to aggregation. These hydrophobic PBAE terpolymers, but not PBAEs lacking alkyl side chains, support interaction with PEG-lipid conjugates, facilitating their functionalization with shielding and targeting moieties and accelerating the in vivo translation of these materials.

Liquid crystalline inorganic nanosheets for facile synthesis of polymer hydrogels with anisotropies in structure, optical property, swelling/deswelling, and ion transport/fixation

Nobuyoshi Miyamoto ,  Morio Shintate ,  Shogo Ikeda ,  Yasutomo Hoshida ,  Yusuke Yamauchi ,  Ryuhei Motokawa and Masahiko Annaka

Abstract: Macroscopically anisotropic hydrogels were synthesized by hybridization of poly(N-isopropylacrylamide) with liquid crystalline inorganic nanosheets; their anisotropies in the structure and properties are demonstrated.

Fig. 1 The photographs of (a–d) the cylindrical F3-B0.01-gel and (d) the sliced gel (ca. 1 mm thick) observed from the top. The gel was observed with the crossed polarizer/analyzer and the wave plate (retardation of 530 nm), whose optical axes are indicated by the blue and black arrows, respectively. Schematic illustration of the gel is shown in (e). The setup for the observation (a) is shown in (f).

This article is quite helpful in our gelator project, since it provides much inspiration in fabricating functional anisotropic materials, one of key words in my research. The way that exploits soft materials like gels or elastomers into liquid crystal (LC) system is noteworthy. And synthetic routes to combine both sides is highly inspiring. This hybrid system makes it promising in optical applications, also pointing out the importance to control the morphology and molecular structure of gels. Future plans in my research involves controlling the assembly of gel fibers, therefore this piece can be a useful reference. 

Mussel-Inspired Adhesive Binders for High-Performance Silicon Nanoparticle Anodes in Lithium-Ion Batteries

Myung-Hyun Ryou, Jangbae Kim, Inhwa Lee, Sunjin Kim, You Kyeong Jeong, Seonki Hong, Ji Hyun Ryu, Taek-Soo Kim, Jung-Ki Park,Haeshin Lee,Jang Wook Choi

Conjugation of mussel-inspired catechol groups to various polymer backbones results in materials suitable as silicon anode binders. The unique wetness-resistant adhesion provided by the catechol groups allows the silicon nanoparticle electrodes to maintain their structure throughout the repeated volume expansion and shrinkage during lithiation cycling, thus facilitating substantially improved specific capacities and cycle lives of lithium-ion batteries.

Efficient Metathesis of Terminal Alkynes

 

Dipl.-Chem. Birte Haberlag, Dr. Matthias Freytag, Dr. Constantin G. Daniliuc, Prof. Dr. Peter G. Jones, Prof. Dr. Matthias Tamm

Now even terminal: The 2,4,6-trimethylbenzylidyne complexes [MesC M{OC(CF3)2Me}3] (M=Mo, W) were synthesized from [Mo(CO)6] and [W(CO)6], respectively. The molybdenum complex is an efficient catalyst for the metathesis of internal and terminal alkynes and also for the ring-closing metathesis of internal and terminal α,ω-diynes at room temperature and low catalyst concentrations.

Surface-Induced Hydrogelation Inhibits Platelet Aggregation

Wenting Zheng †, Jie Gao †, Lijie Song †, Chongyi Chen §, Di Guan †, Zhihong Wang †, Zhibo Li *§, Deling Kong *†, and Zhimou Yang *†

We demonstrate that a tripeptide hydrogelator, Nap-FFG, can selectively self-assemble at the surface of platelets, thus inhibiting ADP-, collagen-, thrombin- and arachidonic acid (AA)-induced human platelet aggregations with the IC50 values of 0.035 (41), 0.14 (162), 0.062 (68), and 0.13 mg/mL (148 μM), respectively. Other tripeptide hydrogelators with chemical structures of Nap-FFX (X = A, K, S, or E) could not or possessed less potencies to inhibit platelet aggregations. We observed higher amounts of Nap-FFG at the platelet surface by the techniques of LC-MS and confocal microscopy. We also observed self-assembled nanofibers around the platelet incubated with the Nap-FFG by cryo-TEM. The ζ potential of Nap-FFG treated platelets was a little bit more negative than that of untreated ones. The amount of Nap-FFG at the surface of NIH 3T3 cells was much less than that of platelets. These observations suggested that Nap-FFG could selectively self-assemble through unknown ligand–receptor interactions and form thin layers of hydrogels at the surface of platelets, thus preventing the aggregation of them. This study not only broadened the application and opened up a new door for biomedical applications of molecular hydrogels but also might provide a novel strategy to counteract infection diseases through selective surface-induced hydrogelations at pathogens, such as bacteria and virus.

Glycans pattern the phase behaviour of lipid membranes

Hydrated networks of glycans (polysaccharides)—in the form of cell walls, periplasms or gel-like matrices—are ubiquitously present adjacent to cellular plasma membranes1, 2, 3, 4. Yet, despite their abundance, the function of glycans in the extracellular milieu is largely unknown5. Here we show that the spatial configuration of glycans controls the phase behaviour of multiphase model lipid membranes: inhomogeneous glycan networks stabilize large lipid domains at the characteristic length scale of the network, whereas homogeneous networks suppress macroscopic lipid phase separation. We also find that glycan-patterned phase separation is thermally reversible—thus indicating that the effect is thermodynamic rather than kinetic—and that phase patterning probably results from a preferential interaction of glycans with ordered lipid phases. These findings have implications for membrane-mediated transport processes6, 7, 8, potentially rationalize long-standing observations that differentiate the behaviour of native and model membranes9, 10, 11, 12, 13 and may indicate an intimate coupling between cellular lipidomes and glycomes.

Liquid-crystal polymers: Exotic actuators

Three-dimensional ordering in liquid-crystalline polymers is induced by the photopolymerization of a mixture of mesogens sandwiched between two patterned substrates. By incorporating an infrared-sensitive dye in the mixture, polymer films that undergo reversible shape deformations on heating are formed.