Self-assembling natural drug hydrogels formed without structural modification and able to act as carriers are of interest for biomedical applications. A lack of knowledge about natural drug gels limits there current application. Here, we report on rhein, a herbal natural product, which is directly self-assembled into hydrogels through noncovalent interactions. This hydrogel shows excellent stability, sustained release and reversible stimuli-responses. The hydrogel consists of a three-dimensional nanofiber network that prevents premature degradation. Moreover, it easily enters cells and binds to toll-like receptor 4. This enables rhein hydrogels to significantly dephosphorylate IκBα, inhibiting the nuclear translocation of p65 at the NFκB signalling pathway in lipopolysaccharide-induced BV2 microglia. Subsequently, rhein hydrogels alleviate neuroinflammation with a long-lasting effect and little cytotoxicity compared to the equivalent free-drug in vitro. This study highlights a direct self-assembly hydrogel from natural small molecule as a promising neuroinflammatory therapy.

Developing active and durable electro-catalysts toward ethanol oxidation reaction (EOR) with high selectivity toward the C-C bond cleavage is an important issue for the commercialization of direct ethanol fuel cell. Unfortunately, current ethanol oxidation electro-catalysts (e.g., Pt, Pd) still suffer from poor selectivity for direct oxidation of ethanol to CO, and rapid activity degradation. Here we report a facile route to the synthesis of a new kind of cyclic penta-twinned (CPT) Rh nanostructures that are self-supported nanobranches (NBs) built with 1-dimension CPT nanorods as subunits. Structurally, the as-prepared Rh NBs possess high percentage of open {100} facets with significant CPT-induced lattice strains. With these unique structural characteristics, the as-prepared CPT Rh NBs exhibit outstanding electrocatalytic performance toward EOR in alkaline solution. Most strikingly, the selectivity of complete conversion ethanol to CO on the CPT Rh NBs is measured to be as high as 14.5 ± 1.1% at -0.15 V, far exceeding that for single-crystal tetrahedral nanocrystals, icosahedral nanocrystals, and commercial Rh black, as well as majority of reported values for Pt or Pd-based electro-catalysts. By combining with density functional theory calculation, the effects of different structural features of Rh on EOR are definitively elucidated. It was found that the large amount of open Rh (100) facets dominantly contribute to the outstanding activity and exceptionally high selectivity, while the additional tensile strain on (100) planes can further boost the catalytic activity by enhancing the adsorption strength and lowering the reaction barrier of dehydrogenation process of ethanol. As a proof of concept, the present work shows that rationally optimizing surface and electronic structure of electro-catalysts by simultaneously engineering their surface and bulk structures is a promising strategy to promote the performance of electro-catalysts.

amount of cross-linked solid. According to the nature of solvents, gels are categorized into hydrogel and organogel to indicate whether the solvent is water or organic solvent(s), respectively. As to the gelation driving forces, gels can be classified into physical gels in which intermolecular interactions are responsible for gel formation, and chemical gels in which the gel skeleton is cross-linked by covalent bonds.Incorporation of metal components (metal ions, metal-organic molecules, and metal nanoparticles) is an effective way to locally establish extra interactions among the building blocks and consequently trigger gel formation, [2][3][4] weaken [5] or enhance [6] gel strength, and modify gel morphology. [7,8] Moreover, addition of metal components is a straightforward way to integrate the specific properties of metals with the properties of organic matrix, therefore to tune properties like conductivity, [9] color, [10,11] rheological behavior, [12] adsorption, [13] emission, [14] photophysical properties, [15] magnetism, [16,17] antibacterial activities, [18,19] catalytic activities, [20][21][22][23] redox activities, [24,25] and selfhealing properties. [26][27][28] Therefore, a broad response range to physical and chemical stimuli can be achieved. For instance, the incorporation of multivalence ions such as Fe 2+ /Fe 3+ , [25,29] Co 2+ / Co 3+ , [30] Cu + /Cu 2+ , [31] results in redox reactive hydrogels; the incorporation of magnetic nanoparticles like Fe 3 O 4[17] causes the gel to respond to external magnetic fields. In addition to the abovementioned intrinsically functional superiorities, metallogels can also serve as ideal templates to generate new materials, [13,22,23,32,33] such as 3D networks, [34] porous structures, [35] chiral materials, [36][37][38] quantum dots, [39] and nanorods. [40] Following the rapid advancement of exploration on the knowledge acquisition toward the major roles that metallogels are playing in catalysis, sensing, biomedicine, electronics, and optical devices, the focus of research has been transferred to the design principles of metallogels in the last decade. Owing to the advancements in the instrumental characterizations and theoretical calculations, [41] a number of pioneering efforts on metallogel design have been made and several innovative reviews have summarized these inspiring contributions. [32,[42][43][44] Despite their extensively acknowledged application advantages in many fields, the discovery of new metallogels with expected functionalities is still highly dependent on experimental screening and serendipity. The challenge stems from the susceptible balance among those complicated intermolecular interactions and the elaborate structure requirements of metallogels.Another research niche that needs to be clarified before discussing recent development of metallogels is: how to sort Introducing metal components into gel matrices provides an effective strategy to develop soft materials with advantageous properties such as: optical activity, conductivity, magn...

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Eight triphenylamine (TPA)-based Schiff bases that exhibit different aggregation-induced emission (AIE) or aggregation-caused quenching (ACQ) behavior in tetrahydrofuran (THF)/water mixtures have been synthesized and characterized. The photophysical properties in solution, aqueous suspension, film, and the crystalline state along with their relationships were comparatively investigated. The single-crystal structures of 1-8 indicate that compact π···π stacking or excimers induce fluorescence quenching of 1, 2, 5, and 7. However, the existence of J aggregates or multiple intra- and intermolecular interactions restrict the intramolecular vibration and rotation, enabling compounds 3, 4, 6, and 8 to exhibit good AIE character. The size and growth process of particles with different water fractions were studied using scanning electron microscopy, which demonstrated that smaller uniformly dispersed nanoparticles in the THF/water mixtures favor fluorescence emission. The above results suggest that the combined effects of multiple forces caused by structural variation have a great influence on their molecular packing, electronic structure, and aggregation-induced fluorescence properties. In addition, piezofluorochromic experiments verified the potential applications of 4 and 6.

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Porous hollow nanostructures have attracted intensive interest owing to their unique structure and promising applications in various fields. A facile hydrothermal synthesis has been developed to prepare porous hollow nanostructures of silicate materials through a sacrificial-templating process. The key factors, such as the concentration of the free metal cation and the alkalinity of the solution, are discussed. Porous hollow nanostructures of magnesium silicate, nickel silicate, and iron silicate have been successfully prepared by using SiO(2) spheres as the template, as well as a silicon source. Several yolk-shell structures have also been fabricated by a similar process that uses silica-coated composite particles as a template. As-prepared mesoporous magnesium silicate hollow spheres showed an excellent ability to remove Pb(2+) ions in water treatment owing to their large specific surface and unique structures.

To balance the requirements of transparency, mechanical strength, stable conductivity, and biocompatibility of traditional electronic conductive hydrogels in intelligent devices is still a formidable challenge. The increase of ionic conductive gels has provided decent transparency, stretchability, and wearability in artificial skins but the dilemma still exists between stability and functionality. This article reports a facile strategy to develop a visual thermosensitive physically and chemically dual cross-linked ion-based conductive hydrogel through in situ free-radical copolymerization, achieving robust mechanical properties, an obvious response, and a multiple sensing process. As an archetypical template, the ion-based conductive hydrogel offers an evaluation and monitoring of electrocardiogram (ECG), which is comparable to commercial electrodes. Intriguingly, such kinds of conductive gels exhibit tunable upper critical solution temperature (UCST) behaviors. Taking advantage of their high temperature responsive accuracy, the visualized qualitative observation for smart response and digitized measurement and calibration for thermal stimulus can be simultaneously achieved. We therefore believe that this work will inspire the design of skinlike sensing materials, promote the preparation of biocompatible and multiple sensing abilities and the synthesis of intelligent hydrogels, and realize their applications in biosensors, wearable devices, and biomedicine.