Seawater-Assisted Self-Healing of Catechol Polymers via Hydrogen Bonding and Coordination Interactions

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, Ca²⁺ and Mg²⁺, the mechanical properties of the polymers were greatly enhanced from viscous to tough, hard materials. Reduced swelling in seawater compared with deionized water owing to the higher osmotic pressure resulted in greater toughness (∼5 MPa) and self-healing efficiencies (∼80%)

Antioxidant and Adsorption Properties of Bioinspired Phenolic Polymers: A Comparative Study of Catechol and Gallol

Polyphenols, which by the Quideau definition are plant-derived chemicals with two or more phenolic groups, have attracted interest because of their antioxidant activity, adsorption on universal substrates, and biocompatibility. Most polyphenols include gallol groups in their chemical structures, which has inspired us to synthesize gallol-functionalized polymers. We report the reversible addition–fragmentation chain transfer polymerization of 3,4,5-trimethoxystyrene using cyanomethyl dodecyl trithiocarbonate as the chain transfer agent. This method produces well-defined polymers with a wide range of molecular weight (from 5.4 to 53.4 kg mol^–1) and low polydispersity index (<i>M</i>_w/<i>M</i>_n < 1.3). Subsequent demethylation of poly­(3,4,5-trimethoxystyrene) (PTMS) yields poly­(3,4,5-trihydroxystyrene) (polyvinylgallol, PVGal). These newly synthesized polymers exhibit greater antioxidant activities than widely used catechol-functionalized polymers based on the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), 2,2′-azinobis­(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and oxygen radical absorbance capacity (ORAC) methods. Also, PVGal showed better adsorption properties on metals and SiO₂ substrates than those of the other phenolic polymers. Given these high antioxidant and adsorption properties, the effective use of gallol-funcationalized polymers in biomaterials is expected

Continuous Metal-Organic Framework Biomineralization on Cellulose Nanocrystals

| openaire: EC/H2020/788489/EU//BioELCellGrowing metal-organic frameworks (MOFs) around biomolecules has recently emerged as a promising method to combine natural and synthetic materials. In parallel, cellulose nanocrystals (CNCs) have found use for forming a wide range of renewable nano- and macroscopic materials because of their bio-derived nature, high surface area, and high strength. Herein, we demonstrate the continuous nucleation of MOFs from the surface of CNCs, thereby forming hybrid hydrogels, aerogels, and porous assemblies that can be pre- or postloaded with functional cargo. With simple mixing of CNCs with MOF precursors, the biomineralization is initiated and takes place continuously where the MOFs simultaneously coat and cross-link the CNCs across a wide range of CNC and MOF precursor concentrations. Additionally, CNCs can be extruded into the premixed MOF precursors to yield CNC-MOF filaments that can be preloaded with functional enzymes or postloaded with small fluorophores. Overall, our approach enables the rapid structural control of functional composites promising for a range of applications.Peer reviewe

Exploiting Supramolecular Interactions from Polymeric Colloids for Strong Anisotropic Adhesion between Solid Surfaces

| openaire: EC/H2020/788489/EU//BioELCellAdhesion 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. However, bottom-up approaches remain elusive given the scarcity of building blocks that yield strong, cohesive, self-assembly across multiple length scales. Herein, an exception is introduced, namely, aqueous dispersions of cellulose nanocrystals (CNCs) that form superstructured, adherent layers between solid surfaces upon confined evaporation-induced self-assembly (C-EISA). The inherently strong CNCs (EA > 140 GPa) align into rigid, nematically ordered lamellae across multiple length scales as a result of the stresses associated with confined evaporation. This long-range order produces remarkable anisotropic adhesive strength when comparing in-plane (≈7 MPa) and out-of-plane (≤0.08 MPa) directions. These adhesive attributes, resulting from self-assembly, substantially outperform previous biomimetic adhesives obtained by top-down microfabrication (dry adhesives, friction driven), and represent a unique fluid (aqueous)-based system with significant anisotropy of adhesion. By using C-EISA, new emergent properties will be closely tied with the nature of colloids and their hierarchical assemblies.Peer reviewe

Stereoselective Synthesis of Tabtoxinine-β-lactam by Using the Vinylogous Mukaiyama Aldol Reaction with Acetate-Type Vinylketene Silyl <i>N</i>,<i>O</i>‑Acetal and α‑Keto-β-lactam

Stereoselective total synthesis of tabtoxinine-β-lactam has been achieved. The vinylogous Mukaiyama aldol reaction with vinylketene silyl <i>N</i>,<i>O</i>-acetal and α-keto-β-lactam proceeded to afford the adduct possessing a TβL-skeleton with a <i>tert</i>-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. A straightforward method to achieve the potent inhibitor of glutamine synthetase, possessing both α-hydroxy-β-lactam and α-amino acid moieties, has been established

Tunicate-Inspired Gallol Polymers for Underwater Adhesive: A Comparative Study of Catechol and Gallol

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. Surprisingly, the newly synthesized copolymers bearing gallol groups exhibited stronger adhesive performances (typically 7× stronger in water) than the widely used catechol-functionalized copolymers under all tested conditions (in air, water, seawater, or phosphate-buffered saline solution). The higher binding strength was ascribed to the tridentate-related interfacial interaction and chemical cross-linking. Moreover, gallol-functionalized copolymers adhered to all tested surfaces including plastic, glass, metal, and biological material. In seawater, the performance of gallol-functionalized copolymer even exceeds the commercially available isocyanate-based glue. The insights from this study are expected to help in the design of biomimetic materials containing gallol groups that may be utilized as potential bioadhesives and for other applications. The results from such a kind of comparable study among phenol, catechol, and gallol suggests that tridentate structure should be better than bidentate structure for bonding to the surface

Targeted Therapy against Metastatic Melanoma Based on Self-Assembled Metal-Phenolic Nanocomplexes Comprised of Green Tea Catechin

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 (Sm3+) are used as building blocks to engineer self-assembled SmIII-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. Moreover, the wound-induced migration of melanoma cells can be efficiently inhibited by SmIII-EGCG, which is a key criterion for metastatic melanoma therapy. In a mouse melanoma tumor model, SmIII-EGCG is directly compared with a clinical anticancer drug, 5-fluorouracil and shows remarkable tumor inhibition. Moreover, the targeted therapy of SmIII-EGCG is shown to prevent metastatic lung melanoma from spreading to main organs with no adverse side effects on the body weight or organs. These in vivo results demonstrate significant advantages of SmIII-EGCG over its clinical counterpart. The results suggest that these green tea-based, self-assembled nanocomplexes possess all of the key traits of a clinically promising candidate to address the challenges associated with the treatment of advanced stage metastatic melanoma.Peer reviewe