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polymers, but they are water-insoluble, organic-solvent basis glues. [10,11] Despite recent novel approaches in adhesives using nanoparticles, [12] stretchable gels, [13] and numerous bioadhesive studies summarized in reviews, [3,4] bioinspired waterborne and biocompatible adhesives showing superglue-like adhesion strength have not been reported. Phenol-amine synergy is also found in insect exoskeletons in which aminerich polymer backbones are cross-linked by phenolic compounds by N-acetyldopamine, N-β-alanyl-dopamine, and dopamine. [14,15] The key biochemistry in sclerotization (i.e., hardening) processes is crosslinking of amine-rich polymers via phenol-quinone involved oxidative reactions. Being different from mechanically weak adhesive materials inspired by marine organisms mentioned above, Young's moduli of exoskeletons are extremely high exhibiting 1-20 GPa, [16] which is similar to ones of common plastics including nylon (2-4 GPa), poly(ethylene terephthalate) (PET) (2-2.7 GPa), and polystyrene (3-3.5 GPa). So far, no studies attempting uses of insect sclerotization process as a new curing strategy in adhesives are reported. We hypothesized that combining: 1) adhesive properties originated from phenols and 2) insect exoskeleton-like hard material properties inspired by phenol-amine phenolamine crosslinking would result in biomimetic superglues. To achieve this goal, the 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. Phenol-amine synergy found in marine mussels or tunicates inspires researchers to develop material-independent surface chemistry and medical soft adhesives. [1] Examples include polydopamine coatings in surface chemistry [2] and catechol-and gallol-tethered soft adhesives. [3-9] Adhesion forces observed from bioinspired adhesive polymers are generally weak in the range of kPa: hyaluronic acid-catechol (0.8 kPa), [5] poly(glutamic acid)-catechol (26.1-58.2 kPa), [6] poly(methacrylamide)-catechol (10-300 kPa), [7] and chitin-gallol (215 kPa). [8] A few studies reported adhesion in MPa ord...

The application of biodegradable and biocompatible materials to triboelectric nanogenerators (TENGs) for harvesting energy from motions of the human body has been attracting significant research interest. Herein, we report diatom bio-silica as a biomaterial additive to enhance the output performance of cellulose nanofibril (CNF)-based TENGs. Diatom frustules (DFs), which are tribopositive bio-silica having hierarchically porous three-dimensional structures and high surface area, have hydrogen bonds with CNFs, resulting in enhanced electrondonating capability and a more roughened surface of the DF−CNF composite film. Hence, DFs were applied to form a tribopositive composite film with CNFs. The DF−CNF biocomposite film is mechanically strong, electron-rich, low-cost, and frictionally rough. The DF−CNF TENG showed an output voltage of 388 V and time-averaged power of 85.5 mW/m 2 in the contact−separation mode with an efficient contact area of 4.9 cm 2 , and the generated power was sufficient for instantaneous illumination of 102 lightemitting diodes. In addition, a cytotoxicity study and biocompatibility tests on rabbit skin suggested that the DF−CNF composite was biologically safe. Moreover, a practical application of the DF−CNF TENG was examined with a self-powered smart mask for human breathing monitoring. This study not only suggests high output performance of biomaterial-based TENGs but also presents the diverse advantages of the DFs in human body-related applications such as self-powered health monitoring masks, skin-attachable power generators, and tactile feedback systems.

Due to its direct and narrow band gap, high chemical stability, and high Seebeck coefficient (1800 μVK−1), antimony selenide (Sb2Se3) has many potential applications, such as in photovoltaic devices, thermoelectric devices, and solar cells. However, research on the Sb2Se3 materials has been limited by its low electrical conductivity in bulk state. To overcome this challenge, we suggest two kinds of nano-structured materials, namely, the diameter-controlled Sb2Se3 nanowires and Ag2Se-decorated Sb2Se3 nanowires. The photocurrent response of diameter-controlled Sb2Se3, which depends on electrical conductivity of the material, increases non-linearly with the diameter of the nanowire. The photosensitivity factor (K = Ilight/Idark) of the intrinsic Sb2Se3 nanowire with diameter of 80–100 nm is highly improved (K = 75). Additionally, the measurement was conducted using a single nanowire under low source-drain voltage. The dark- and photocurrent of the Ag2Se-decorated Sb2Se3 nanowire further increased, as compared to that of the intrinsic Sb2Se3 nanowire, to approximately 50 and 7 times, respectively.

COMMUNICATION 1900275 (1 of 8)

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