Publications by authors named "Hirotaka Ejima"

Coarse-grained molecular dynamics (CG-MD) simulations and subsequent persistent homology (PH) analysis were performed to correlate the structure and stress-strain behavior of polymer films. During uniaxial tensile MD simulations, the first principal component of the persistence diagram obtained by principal component analysis (PCA) was in good agreement with the stress-strain curve. This indicates that PH + PCA can identify critical ring structures relevant to the dynamic changes in MD simulations without requiring any prior knowledge.

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Individuals with autism spectrum disorder (ASD) have a higher prevalence of social memory impairment. A series of our previous studies revealed that hippocampal ventral CA1 (vCA1) neurons possess social memory engram and that the neurophysiological representation of social memory in the vCA1 neurons is disrupted in ASD-associated Shank3 knockout mice. However, whether the dysfunction of Shank3 in vCA1 causes the social memory impairment observed in ASD remains unclear.

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Films formed by metals and phenols through a coordinative interaction have been extensively studied in previous years. We report the successful formation of MPN films from the phenolic compounds caffeic acid and lignosulfonate using Fe ions for complexation. The likewise examined -coumaryl alcohol showed some MPN film formation tendency, while for coniferyl alcohol and sinapyl alcohol, no successful film buildup could be observed.

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Article Synopsis
  • The study focuses on a novel "nano trap" designed to combat breast cancer by preventing the evasion of cell death, a common issue in tumor progression and treatment resistance.
  • This nano trap utilizes disulfiram-loaded nanoparticles combined with calcium and copper ions, which trigger both paraptosis and apoptosis in cancer cells through a carefully engineered release mechanism.
  • Experimental results indicate that this dual-ion approach effectively enhances cancer treatment outcomes by inducing cell death and could reshape future strategies for managing tumorigenesis.
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Adsorption energies of additive molecules in paint materials on the iron oxide substrate are investigated by molecular dynamics (MD) simulations to find the key feature of adhesion, which is one of the indispensable elements for the corrosion resistance of coated materials. Both edge-on and face-on adsorptions are observed for most additive molecules such as phenylsuccinic acid and benzoic acid. On the other hand, only the edge-on adsorption is observed for the specific molecule having a benzothiazole ring due to the effect of steric conformation.

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Calcium carbonate (CaCO) is a naturally occurring mineral that occurs in biology and is used industrially. Due to its benign nature, CaCO microparticles have found use in the food and medical fields, where the specific size of the microparticles determine their functionality and potential applications. We demonstrate that phenolic polymers with different numbers of hydroxy groups can be used to control the diameter of CaCO microparticles in a range of 2-9 μm, and obtained particles were relatively uniform.

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Drug-dependent design of hydrogels is currently required for engineering the controlled release of therapeutics, which is a major contributor to the technical challenges relating to the clinical translation of hydrogel-drug systems. Herein, by integrating supramolecular phenolic-based nanofillers (SPFs) into hydrogel microstructures we developed a facile strategy to endow a range of clinically relevant hydrogels with controlled release properties for diverse therapeutic agents. The assembly of multiscale SPF aggregates leads to tunable mesh size and multiple dynamic interactions between SPF aggregates and drugs, which relaxes the available choices of drugs and hydrogels.

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Tannic acid (TA) is a structurally undefined natural dendritic polyphenol. Here, we introduce a series of TA-inspired polymers with different arm lengths, , and phenolic groups that can be used to engineer metal-phenolic network (MPN) capsules with different properties including controlled permeability, high biocompatibility, and fluorescence.

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We present a dry pick-and-flip assembly technique for angle-resolved photoemission spectroscopy (ARPES) of van der Waals heterostructures. By combining Elvacite2552C acrylic resin and 1-ethyl-3-methylimidazolium ionic liquid, we prepared polymers with glass transition temperatures (T) ranging from 37 to 100 ℃. The adhesion of the polymer to the 2D crystals was enhanced at [Formula: see text].

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Robust underwater adhesion is challenging because a hydration layer impedes the interaction between substrates and adhesives. Phenolic adhesives inspired by marine creatures such as mussels were extensively studied, but these adhesives have not reached the adhesion strength and substrate diversity of Man-made dry adhesives. Here, we report a class of ultrastrong underwater adhesives with molecular phenolic designs extending beyond what nature has produced.

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New materials for combating bacteria-caused infection and promoting the formation of microvascular networks during wound healing are of vital importance. Although antibiotics can be used to prevent infection, treatments that can disinfect and accelerate wound healing are scarce. Herein, we engineer a coating that is both highly compatible with current wound dressing substrates and capable of simultaneously disinfecting and revascularizing wounds using a metal-phenolic nanoplatform containing an alloyed nanostructured architecture (Ag@Cu-MPN).

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The development of antimicrobial fabrics and textiles that can sustainably inhibit a broad spectrum of microbes is crucial for protecting against pathogens in various environments. However, engineering antimicrobial textiles is challenging due to issues with discoloration and inhibited breathability, the use of harmful or harsh reagents and synthesis conditions, and complex and/or time-consuming processing. Herein, we develop a facile and rapid approach to deposit antimicrobial coatings using universally adherent plant polyphenols and antimicrobial silver ions.

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Although the synthesis of thiophenol-pendant polymers was reported in the 1950s, the polymers generally suffered from oxidation and became insoluble in organic solvents, hampering detailed characterization and further applications. Dithiocatechol-pendant polymers, which have one additional ortho-thiol group than thiophenol-pendant polymers, have never been synthesized, despite their promise in various applications due to their analogous molecular structure with catechol-pendant polymers. Herein, we report the first synthesis of dithiocatechol-pendant polymers using a novel protection-deprotection strategy.

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Despite high demands from various industries, strong adhesion in a wet environment remains challenging. We investigated the underwater adhesion of gallol-functionalized polymers as a function of molecular weight and gallol content. By optimizing these parameters, the underwater adhesion strength of aluminium substrates exceeded 4 MPa.

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Adhesion occurs by covalent bonding, as in reactive structural adhesives, or through noncovalent interactions, which are nearly ubiquitous in nature. A classic example of the latter is gecko feet, where hierarchical features enhance friction across the contact area. Biomimicry of such structured adhesion is regularly achieved by top-down lithography, which allows for direction-dependent detachment.

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Polyphenols are building blocks with many advantages for engineering biomaterials because they are abundant in nature, biocompatible, biodegradable, and capable of assembly through different mechanisms. A variety of biomaterials across different length scales can be made with different physical/chemical properties and unique stimuli responses using modular and straightforward synthesis routes. We review the recent progress of biomaterials engineering based on polyphenols under three broad categories, namely, particles, films, and gels.

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The targeted therapy of metastatic melanoma is an important yet challenging goal that has received only limited attention to date. Herein, green tea polyphenols, (-)-epigallocatechin-3-gallate (EGCG), and lanthanide metal ions (Sm) are used as building blocks to engineer self-assembled Sm-EGCG nanocomplexes with synergistically enhanced tumor inhibitory properties. These nanocomplexes have negligible systemic toxic effects on healthy cells but cause a significant reduction in the viability of melanoma cells by efficiently regulating their metabolic pathways.

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Metal-phenolic network (MPN) coatings have generated increasing interest owing to their biologically inspired nature, facile fabrication, and near-universal adherence, especially for biomedical applications. However, a key issue in biomedicine is protein fouling, and the adsorption of proteins on tannic acid-based MPNs remains to be comprehensively studied. Herein, we investigate the interaction of specific biomedically relevant proteins in solution (e.

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Background: Porous micro- and nanoparticles have the capacity to encapsulate a large quantity of therapeutics, making them promising delivery vehicles for a variety of applications. This review aims to highlight the latest development of inorganic and hybrid (inorganic/ organic) particles for drug delivery with an additional emphasis on combatting drug resistant cancer. We go one step further and discuss delivery applications beyond medicinal delivery, as there is generally a translation from medicinal delivery to botanic delivery after a short lag time.

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Man-made glues often fail to stick in wet environments because of hydration-induced softening and dissolution. The wound healing process of a tunicate inspired the synthesis of gallol-functionalized copolymers as underwater adhesive. Copolymers bearing three types of phenolic groups, namely, phenol, catechol, and gallol, were synthesized via the methoxymethyl protection/deprotection route.

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Stereoselective total synthesis of tabtoxinine-β-lactam has been achieved. The vinylogous Mukaiyama aldol reaction with vinylketene silyl N,O-acetal and α-keto-β-lactam proceeded to afford the adduct possessing a TβL-skeleton with a tert-alcohol in high yield and stereoselectivity. Stereoselective introduction of the amino group has been accomplished by azidation at the α position of the imide followed by hydrogenolysis.

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Methods for depositing thin films are important in generating functional materials for diverse applications in a wide variety of fields. Over the last half-century, the layer-by-layer assembly of nanoscale films has received intense and growing interest. This has been fueled by innovation in the available materials and assembly technologies, as well as the film-characterization techniques.

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Materials assembled by coordination interactions between naturally abundant polyphenols and metals are of interest for a wide range of applications, including crystallization, catalysis, and drug delivery. Such an interest has led to the development of thin films with tunable, dynamic properties, however, creating bulk materials remains a challenge. Reported here is a class of metallogels formed by direct gelation between inexpensive, naturally abundant tannic acid and group(IV) metal ions.

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Supramolecular polymers with monomers bound together by secondary interactions, such as polyrotaxanes (PRXs), consisting of alpha cyclodextrin (αCD) threaded onto poly(ethylene glycol) (PEG), have attracted interest as a result of their ability to overcome physical limitations present in conventional, covalently structured polymers. Herein, we describe the formation of pH-responsive supramolecular assemblies from carboxyethylester bearing αCD and PEG PRXs. These PRXs were formed using PEG of Mw 20 kDa and a threading degree of 28%.

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It is highly desirable to prevent crack formation in polymeric materials at an early stage and to extend their lifespan, particularly when repairs to these materials would be difficult for humans. Here, we designed and synthesized catechol-functionalized polymers that can self-heal in seawater through hydrogen bonding and coordination. These bioinspired acrylate polymers are originally viscous materials, but after coordination with environmentally safe, common metal cations in seawater, namely, Ca(2+) and Mg(2+), the mechanical properties of the polymers were greatly enhanced from viscous to tough, hard materials.

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