Autonomous Motion of Hydrogels Driven by Semi-Interpenetrating Chemical Processing Systems.

Developing artificial autonomous materials is crucial for a deeper understanding of the emergence of life-like behavior. In nature, cells achieve autonomy through chemical processing systems incorporated into soft material-based frameworks. Inspired by natural cells, we herein describe a straightforward methodology for constructing artificial autonomous materials consisting of a polymer-based chemical processing system and a hydrogel-based soft framework.

Emergent Synchronous Volumetric Oscillation in Hierarchically Structured Self-Oscillating Gel Clusters.

Emergent properties accompanying synchronization among oscillators are vital characteristics in biological systems. Belousov-Zhabotinsky (BZ) oscillators are an artificial model to study the emergence and synchronization in life. This research represents a self-oscillating gel system with clusterable properties to experimentally examine synchronous and emergent properties at a fundamental hierarchical level.

Temperature-Adaptative Self-Oscillating Gels: Toward Autonomous Biomimetic Soft Actuators with Broad Operating Temperature Region.

Self-oscillating gel systems exhibiting an expanded operating temperature and accompanying functional adaptability are showcased. The developed system contains nonthermoresponsive main-monomers, such as N,N-dimethylacrylamide (DMAAm) or 2-acrylamido-2-methylpropane sulfonic acid (AMPS) or acrylamide (AAm) or 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC). The gels volumetrically self-oscillate within the range of the conventional (20.

Anisotropically self-oscillating gels by spatially patterned interpenetrating polymer network.

Here we introduce sub-millimeter self-oscillating gels that undergo the Belousov-Zhabotinsky (BZ) reaction and can anisotropically oscillate like cardiomyocytes. The anisotropically self-oscillating gels in this study were realized by spatially patterning an acrylic acid-based interpenetrating network (AA-IPN). We found that the patterned AA-IPN regions, locally introduced at both ends of the gels through UV photolithography, can constrain the horizontal gel shape deformation during the BZ reaction.

A surface-grafted hydrogel demonstrating thermoresponsive adhesive strength change.

Here, we designed a surface-grafted hydrogel (SG gel) that exhibits thermoresponsive changes in surface properties. Quantitative measurements using a self-made device showed that the adhesive strength between the SG gel surface and a Bakelite plate due to hydrophobic interaction changed significantly with temperature.

Fabrication of submillimeter-sized spherical self-oscillating gels and control of their isotropic volumetric oscillatory behaviors.

In this study, we established a fabrication method and analyzed the volumetric self-oscillatory behaviors of submillimeter-sized spherical self-oscillating gels. We validated that the manufactured submillimeter-sized spherical self-oscillating gels exhibited isotropic volumetric oscillations during the Belousov-Zhabotinsky (BZ) reaction. In addition, we experimentally elucidated that the volumetric self-oscillatory behaviors (, period and amplitude) and the oscillatory profiles depended on the following parameters: (1) the molar composition of -(3-aminopropyl)methacrylamide hydrochloride (NAPMAm) in the gels and (2) the concentration of Ru(bpy)-NHS solution containing an active ester group on conjugation.

Capsule self-oscillating gels showing cell-like nonthermal membrane/shape fluctuations.

A primary interest in cell membrane and shape fluctuations is establishing experimental models reflecting only nonthermal active contributions. Here we report a millimeter-scaled capsule self-oscillating gel model mirroring the active contribution effect on cell fluctuations. In the capsule self-oscillating gels, the propagating chemical signals during a Belousov-Zhabotinsky (BZ) reaction induce simultaneous local deformations in the various regions, showing cell-like shape fluctuations.

Region-dependent volumetric oscillation of self-oscillating gels with gradient transducers.

Heartbeats with different ventricular contractions vary with heart regions, which can be described as anisotropy. Herein, we report self-oscillating gels which exhibit region-dependent anisotropic volumetric oscillation behavior similar to that of the heart. We installed a (Ru(bpy)) gradient transducer on self-oscillating gels by employing slow and unidirectional diffusion in the gels and dipping part of the gel into a Ru(bpy)-NHS solution.

Fabrication of Self-Oscillating Gels by Polymer Crosslinking Method and Analysis on Their Autonomous Swelling-Deswelling Behaviors.

We have developed a new methodology for fabricating self-oscillating gels by a post-polymerization crosslinking. The method enables us to make the self-oscillating gels easily just by mixing two kinds of polymer solutions at room temperature with fast gelation. Moreover, the polymer crosslinking method has the advantage that the self-oscillating gels could be fabricated from well-defined linear polymers.

Construction of a nano-phase-separated structure on a hydrogel surface.

A hydrogel surface with a nano-phase-separated structure was successfully fabricated by grafting a fluorine-containing polymer using activators regenerated by electron transfer atom transfer radical polymerisation (ARGET ATRP). The modified hydrogel surface exhibits water repellency and high elasticity with maintaining transparency.

Dirhodium-Based Supramolecular Framework Catalyst for Visible-Light-Driven Hydrogen Evolution.

The direct conversion of solar energy to clean fuels as alternatives to fossil fuels is an important approach for addressing the global energy shortage and environmental problems. Here, we introduce a new dirhodium-complex-based framework assembly as a heterogeneous molecule-based photocatalyst for hydrogen evolution using visible light. Two dirhodium complexes bearing visible-light-harvesting BODIPY (boron dipyrromethene, BDP) moieties were newly designed and synthesized.

Effect of metal ion substitution on the catalytic activity of a pentanuclear metal complex.

A pentanuclear cobalt complex that consists of five cobalt ions and six bpp ligands (Co5, Hbpp = 3,5-bis(2-pyridyl)pyrazole) was synthesized and crystallographically characterized. Electrochemical measurements indicate that Co5 has multielectron transfer ability. We also found that Co5 reduces CO to CO under photoirradiation in the presence of a photosensitizer.

Unveiling Latent Photoreactivity of Imines.

Unlike carbonyl compounds, it has long been common understanding that excited imines show virtually no photoreactivity, and hence their properties and potential utility in chemical science remain largely unexplored. Now, a strategy is presented for eliciting latent photoreactivity of imines based on the introduction of a donor-acceptor (D-A) structure to extend the lifetime of their photoexcited states. A series of spectroscopic analyses and density functional theory calculations reveal unique photophysical properties of the D-A-type imines.

Proton-Coupled Electron Transfer Induced by Near-Infrared Light.

A proton-coupled electron transfer reaction induced by near-infrared light (>710 nm) has been achieved using a dye that shows intense NIR absorption property and electron/proton-accepting abilities. The developed system generated long-lived radical species and showed high reversibility and robustness. Mechanistic investigations suggested that the rate-determining step of the reaction involves the proton transfer process.

Function-Integrated Ru Catalyst for Photochemical CO Reduction.

Visible-light-driven catalytic reduction of CO is at the heart of artificial photosynthesis. Here, we demonstrate the first example of a Ru complex that can function both as a photosensitizer and catalyst for CO reduction. The catalyst exhibited excellent activity for CO evolution with a high turnover number (TON, 353 for 24 h), reaction rate (TOF, 14.

C(sp )-H Cyanation Promoted by Visible-Light Photoredox/Phosphate Hybrid Catalysis.

Inspired by the reaction mechanism of photo-induced DNA cleavage in nature, a C(sp )-H cyanation reaction promoted by visible-light photoredox/phosphate hybrid catalysis was developed. Phosphate radicals, generated by one-electron photooxidation of phosphate salt, functioned as a hydrogen-atom-transfer catalyst to produce nucleophilic carbon radicals from C(sp )-H bonds with a high bond-dissociation energy. The resulting carbon radicals were trapped by a cyano radical source (TsCN) to produce the C-H cyanation products.

In Situ Lipid Membrane Formation Triggered by Intramolecular Photoinduced Electron Transfer.

A major goal of synthetic biology is the development of rational methodologies to construct self-assembling non-natural membranes, which could enable the efficient fabrication of artificial cellular systems from purely synthetic components. However, spatiotemporal control of artificial membrane formation remains both challenging and limited in scope. Here, we describe a new methodology to promote biomimetic phospholipid membrane formation by the photochemical activation of a catalyst-sensitizer dyad via an intramolecular photoinduced electron-transfer process.

Titania may produce abiotic oxygen atmospheres on habitable exoplanets.

The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms.