Interface engineering of heterogeneous transition metal chalcogenides for electrocatalytic hydrogen evolution.

MoS2 and MoSe2 are recognized as promising electrocatalysts for the hydrogen evolution reaction (HER), but the active sites are mainly located on the edge, limiting their electrochemical efficiency. Here we have introduced the 2H-1T' interface structures in MoSSe and MoS2-MoSe2 heterostructures to enhance the HER activity in the basal planes by using the density functional theory (DFT) calculations. The structural stability and electronic properties of different 2H-1T' interface structures are investigated and the HER activities are evaluated by using the H adsorption free energy (ΔG H). The H adsorption free energy along the interface boundaries is very close to zero, and the optimal sites for the HER are the S or Se atoms, which are bonded with three Mo atoms and located in the center of a hexagonal ring composed of three Mo atoms and three halogen atoms. Our study provides a different approach to activate the basal planes and efficiently improve the electrochemical HER performance of transition metal dichalcogenide materials.

Chitosan Hydrogel Delivery System Containing Herbal Compound Functions as a Potential Antineuroinflammatory Agent.

Rhein (4,5-dihydroxyanthraquinone-2-carboxylic acid) is an anthraquinone compound mainly isolated from the herbal medicine rhubarb. It possesses a wide spectrum of pharmacological effects. However, the lack of sustained release properties and the poor bioavailability hinder clinical transformation. Hydrogel-based drug delivery system provides an ideal carrier to improve the release control and the therapeutic efficacy of drugs. Herein, we present a chitosan hydrogel for the delivery of rhein. This rhein-chitosan hydrogel (CS-Rh gel) exhibited superior characteristics including mechanical strength, sustained release, and low toxicity. For medical application, the enzyme-linked immunosorbent assay and Western blot analyses indicated that CS-Rh gel significantly suppressed the production of proinflammatory cytokines including TNF-α and IL-1ß in lipopolysaccharide-induced BV2 cells. Additionally, CS-Rh gel blocked the neuroinflammation-related mitogen-activated protein kinase (JNK, ERK, and p38)-signaling pathways. Interestingly, these inhibitory effects at 48 h outperformed the pharmacologic actions at 24 h, showing that the CS-Rh gel exerted optimal sustained antineuroinflammation. This study highlights a novel chitosan hydrogel containing rhein used as a potential antineuroinflammatory agent.

A natural cordycepin/chitosan complex hydrogel with outstanding self-healable and wound healing properties.

The chitosan-based hydrogel dressings have been intensively engaged in wound healing. In respect to the relatively unsatisfied anti-bacterial performance of chitosan, we developed a self-healable cordycepin (abbreviated to CY)/chitosan (abbreviated to CS) hydrogel dressing cross linking by non-covalent bonds (hydrogen bond and electrostatic interaction) for wound healing through one-step 'freeze-thaw' method without adding any cross-linking agent. The as-prepared hybrid hydrogel exhibited excellent biocompatibility, suitable swelling ratio and desired mechanical strength, providing remarkable antimicrobial effect with no side effects in vitro. The self-healable property enables this hydrogel to adapt irregularly shaped wound defects without premolding. Moreover, our in vivo experiments confirmed that CY/CS hydrogel served as a quicker re-epithelization of skin wounds and an apparent increasing collagen deposition compared with chitosan hydrogels. Additionally, the CY/CS hydrogel significantly increased the expressions of epithelial regeneration markers including laminin and involucrin. The present study highlights a facile hydrogel strategy to balance and optimize the biocompatibility, swelling ratio and self-adapting ability for treating wound healing.