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β-chitin nanofibers (β-ChNFs) were efficiently prepared from squid pens by a combination of ball milling and ultrasonic techniques. The gellation of the β-ChNFs dispersion was achieved through a dialysis neutralization process, and hydrogels, even at 0.2% solid content, had high stiffness, as indicated by the dynamic viscoelasticity measurements. The β-ChNFs hydrogels were used as scaffolds to fabricate ultra-small silver nanoparticles (AgNPs) by in situ ultraviolet (UV) photo-reduction. High-angle annular dark-field scanning transmission energy microscopy (HAADF-STEM) analysis showed that 4 nm monodispersed AgNPs were produced in the hydrogel framework, and X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy analysis revealed the strong interaction between AgNPs and the chitin nanofiber matrix. Furthermore, biological evaluation showed no cytotoxicity and excellent bactericidal activity of the silver nanoparticle-impregnated β-chitin nanofiber hydrogels, thus suggesting that they are promising materials to heal refractory wounds. [ABSTRACT FROM AUTHOR]

Highlights • In situ injectable hydrogels based on polyelectrolyte complexes were prepared. • Chitosan oligosaccharide induced a two-stage gelling process and stronger hydrogels. • Chitosan oligosaccharide notably helped to accelerate the wound healing. Abstract In situ injectable hydrogels for wound healing based on carboxymethyl chitosan (CMCS) and alginate were developed in this work. The liquid mixture of CMCS and alginate solutions formed a gel by polyelectrolyte complexation after addition of d -glucono- δ -lactone (GDL), which slowly hydrolyzed and donated protons. When chitosan oligosaccharide (COS) was added into the mixture, a two-stage gelling process occurred. The primary gelling process was similar to that of the hydrogel without COS, while the secondary gelling process appeared about 20 min later, and much stronger hydrogels with storage modulus G' about 1 MPa, 104 times higher, were obtained. COS also significantly influenced the microstructure of hydrogels as well as their biological activities. The hydrogels with 0.5% of COS significantly promoted proliferation of human umbilical cord mesenchymal stem cells (HUMSCs). These injectable hydrogels, especially when COS was added, remarkably accelerated the wound healing process in a mouse skin defect model. Microscopic wound analysis showed an increase of the thickness and integrity of epidermal tissue, increased formation of collagen fibers, and enhanced expression of vascular endothelial growth factor as compared to the control group. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) will assist the development of all-solid-state lithium batteries by identifying their performance limiting resistances, although an elaborate distinction method has not been established to date. Herein, the distribution-of-relaxation-times method was used to support the quantification and understanding of EIS data, which were compiled over various temperatures and states of charge (SOCs) for all-solid-state cells with an In–Li anode, coated-LiCoO 2 composite cathode, and separator comprising two kinds of sulfide solid electrolytes (SEs): Li 10+ x Ge 1+ x P 2− x S 12 (LGPS) or its structural analogue in the Li–P–S–Br system (LPSBr). It was revealed that the In–Li interface and interphase resistances differ significantly depending on the separator SE, confirming an imperceptible chemical reaction between In–Li/LPSBr and the chemical instability of In–Li/LGPS. Consequently, the LGPS-based cell suffers from a large total impedance (188 Ω at 298 K and 100% SOC with 151 Ω at Li–In/LGPS), which is 250% higher than that of the LPSBr-based cell (66 Ω with 18 Ω at Li–In/LPSBr). This study provides guidance for the quantitative analysis of EIS data and in improvement of battery performance, such as developing new SEs that are as ion-conductive as LGPS and as stable as LPSBr. [Display omitted] • Impedance spectroscopy was performed for sulfide-based solid-state battery cells. • Two types of sulfide solid electrolytes were compared. • Impedance contributions were separated by distribution of relaxation time analysis. • State-of-charge and temperature dependencies were clarified for each resistance. • Interphase and interface resistances at metal anode side were found to be dominant. [ABSTRACT FROM AUTHOR]

• Coadsorption of octanethiol (OT) and octyl thiocyanate (OTC) on Au(111). • Phase behaviors of coadsorbed self-assembled monolayers (SAMs) were examined. • OT SAMs are dominantly formed at molar concentration ratio of OT:OTC = 50:50. • Phase-separated OT and OTC SAMs are formed at molar ratio of OT:OTC = 5:95. • Adsorption of OT on Au(111) is much faster than OTC. To understand headgroup effects on phase behaviors of self-assembled monolayers (SAMs) prepared by coadsorption of octanethiol [OT, CH 3 (CH 2) 7 –SH] and octyl thiocyanate [OTC, CH 3 (CH 2) 7 –SCN] on Au(111) as a function of the OT:OTC molar concentration ratio, we investigated the surface structures of the resulting SAMs formed in 1 mM ethanol solutions at 50 °C for 24 h using scanning tunneling microscopy (STM). The STM study showed that the single-component OT SAMs were composed of an ordered c(4 × 2) phase, whereas single-component OTC SAMs had a binary phase consisting of a disordered phase and a striped phase with a distance of 1.3 ± 0.1 nm between rows. The fully covered c(4 × 2) phase on Au(111) formed by OT molecules was observed even a molar concentration ratio of OT is equal to OTC (50:50) or is much lower than OTC (10:90). The partially covered striped phase formed by OTC molecules was observed when the molar concentration ratios of OTC were much higher than OT (OT:OTC = 5:95 or OT:OTC = 1:99). Molecular-scale STM results clearly reveal the phase transitions of SAMs on Au(111) via coadsorption of OT and OTC depending on OT:OTC molar ratio. These results will help advance understanding of SAM formation and phase behavior on Au(111) by the coadsorption of alkanethiol and alkyl thiocyanates. [ABSTRACT FROM AUTHOR]