A Phenol-Amine Superglue Inspired by Insect Sclerotization Process.

Exoskeletons of insects formed by sclerotization processes exhibit superstrong properties in moduli. Here, it is demonstrated that mimicking the sclerotization process using phenol and polyamine molecules unexpectedly results in a 100% ecofriendly, biocompatible waterborne superglue. Oxygen presented in air and dissolved in water acts as an initiator producing phenolic radical/quinone for superglue curing. Despite synthesis-free uses of water, phenol, and polyamine, its adhesion strength is comparable to commercial epoxy glue showing >6 MPa in lap shear strength. The phenol-amine superglue bonds to various substrates including ceramics, woods, fabrics, plastics, metals, and importantly biological tissues. Due to strong adhesion, the superglue effectively seals wounds within a few seconds, and, due to its waterborne nature, no harmful respiratory effect is observed because of any release of volatile organic compounds. The easy, cost-effective preparation of the phenol-amine superglue can revolutionize varieties of industrial, biomedical, daily life processes.

Progressive fuzzy cation-π assembly of biological catecholamines.

Biological functions depend on biomolecular assembly processes. Assemblies of lipid bilayers, actins, microtubules, or chromosomes are indispensable for cellular functions. These hierarchical assembly processes are reasonably predictable by understanding chemical structures of the defined building blocks and their interactions. However, biopigment assembly is rather fuzzy and unpredictable because a series of covalently coupled intermediates from catecholamine oxidation pathways progressively form a higher-level hierarchy. This study reports a different yet unexplored type of assembly process named "cation-π progressive assembly." We demonstrated for the first time that the cation-π is the primary mechanism for intermolecular assembly in dopamine-melanin biopigment. We also found that the self-assembled products physically grow and chemically gain new functions "progressively" over time in which cation-π plays important roles. The progressive assembly explains how biological systems produce wide spectra of pigment colors and broad wavelength absorption through energy-efficient processes. Furthermore, we also demonstrate surface-independent wettability control using cation-π progressive assembly.

Hemostatic Ability of Chitosan-Phosphate Inspired by Coagulation Mechanisms of Platelet Polyphosphates.

Hemostatic materials have been studied to minimize bleeding time. Recently, polyphosphate (polyP) have received attention as potential hemostatic compounds, which are released from activated platelets. Long polyP chains are essential to form thick fibrin clots. Herein, chitosan is functionalized by covalently tethering phosphate groups to mimic polyP. It is hypothesized that utilizing a known hemostatic polysaccharide, chitosan, and tethering phosphate groups to mimic polyP's functionality show synergistic effect in hemostasis. Five different phosphorylated chitosan conjugates (Chi-Ps), s-Chi-7P, s-Chi-28P, s-Chi-74P, is-Chi-29P, and is-Chi-56P are prepared, where "s" indicates water soluble Chi-Ps and "is" represents water insoluble Chi-Ps. Unexpectedly, an important carbon in D-glucosamine is found, which determines chitosan solubility. Phosphate groups conjugated to C6 carbon resulted in water soluble Chi-P, but conjugation to C3 group exhibited water insoluble behavior. Hemostasis capability showed a positive correlation with the degree of phosphate conjugations regardless of water solubility of Chi-P.

A "Sticky" Mucin-Inspired DNA-Polysaccharide Binder for Silicon and Silicon-Graphite Blended Anodes in Lithium-Ion Batteries.

New binder concepts have lately demonstrated improvements in the cycle life of high-capacity silicon anodes. Those binder designs adopt adhesive functional groups to enhance affinity with silicon particles and 3D network conformation to secure electrode integrity. However, homogeneous distribution of silicon particles in the presence of a substantial volumetric content of carbonaceous components (i.e., conductive agent, graphite, etc.) is still difficult to achieve while the binder maintains its desired 3D network. Inspired by mucin, the amphiphilic macromolecular lubricant, secreted on the hydrophobic surface of gastrointestine to interface aqueous serous fluid, here, a renatured DNA-alginate amphiphilic binder for silicon and silicon-graphite blended electrodes is reported. Mimicking mucin's structure comprised of a hydrophobic protein backbone and hydrophilic oligosaccharide branches, the renatured DNA-alginate binder offers amphiphilicity from both components, along with a 3D fractal network structure. The DNA-alginate binder facilitates homogeneous distribution of electrode components in the electrode as well as its enhanced adhesion onto a current collector, leading to improved cyclability in both silicon and silicon-graphite blended electrodes.

Biologically Inspired Materials Exhibiting Repeatable Regeneration with Self-Sealing Capabilities without External Stimuli or Catalysts.

A new insect-cuticle- and fruit-browning-mimetic film exhibiting simultaneous self-healing and self-sealing properties only by ambient oxygen without external stimuli is developed. The film is formed at the liquid/air interface via crosslinking of phenolic compounds and poly(amine) chains. The film can be self-healed over a hundred times under ambient air at room temperature without exogenous materials and stimuli.