Latest ArticlesSkin is the largest organ in human body, and it plays an important role in regulating physiological microenvironments and acts as a barrier to protect human body from harmful intrusions. The demand for fully functional skin models (also called skin equivalents, SE) in an in-vivo mimicking culturing microenvironment has been increased dramatically due to the fast development in skin disease treatments and skin care products. Owing to the emerging of the concept and technology of organ-on-chips along with the three-dimensional (3D) bioprinting technology, 3D skin models and their applications have been fast evolving. In this paper, the advances in the development of 3D skin models along with skin-on-a-chip (SOC) are reviewed and commented. One of the findings with this paper is that the SOC together with the 3D bioprinting technology is promising to construct fully functional 3D skin models in the field of pharmaceutical and cosmetic industries.
In recent twenty years, aggregation-induced emission (AIE), due to its excellent application prospect, has aroused widespread interests. The development of novel and easy to make AIE luminogens (AIEgens) is an attractive subject. For this purpose, it is very important to study the structure-property relationship of AIEgens. Because azine derivatives are easy to synthesis and some of them have nice AIE properties, herein, a series of azine derivatives (ADs) were employed as models to study the influence of different functional groups, electronic effects and structures on the AIE properties of azine derivatives. The AIE mechanism were studied by single crystal analysis, density functional theory (DFT) calculations and so on. The results indicated that the o-hydroxyl aryl substituted azine compounds could show good AIE properties. Meanwhile, the AIE properties of o-hydroxyl aryl substituted azine compounds were also influenced by the electronic effects of the aryl groups in the azine compounds. The o-hydroxyl groups could form intramolecular hydrogen bond with imine group, which play key role to restrict the intramolecular rotation of the aryl groups and act as base stone for the AIE process of this kind compounds. The HOMO-LUMO energy gaps of o-hydroxyl substituted azine are smaller than other homologous compounds, which is agree with the proposed AIE mechanism. Finally, thanks to the AIE properties, the o-hydroxy-substituted azines could be used as efficient Al3+ and Cu2+ fluorescent chemosensors in different conditions. In addition, test strips based on AD10 has been prepared, which can conveniently detect Cu2+ in industrial wastewater. This research supplied a way for the design of novel easy to make AIEgens through simple azine derivatives.
A novel photoredox-neutral ring-opening pyridylation of non-prefunctionalized cyclic oximes has been accomplished through phosphoranyl radical-mediated NO/CC bond cleavages followed by radical-radical coupling. This mild acid-, base-, and oxidant-free protocol provides highly site-selective and efficient access to distally pyridylated alkylnitriles, which could be scale-up synthesized and readily converted into skeletally diverse compounds. Notably, the oxidized ground-state photocatalyst generated via the SET oxidation of the highly reducing excited-state photocatalyst by cyanopyridines might initiate the following phosphoranyl radical-mediated deoxygenative process.
Photodynamic therapy (PDT) agents may accumulate in skin and cause severe skin cytotoxicity. We report a pro-guest-based supramolecular strategy to selectively activate PDT in the reactive oxygen specie (ROS) overexpressed microenvironment, which is often existing in tumor and inflammatory tissues. PDT agents methylene blue (MB) and basic blue 17 (BB17) are used as model drugs. When encapsulated by acyclic cucurbit[n]uril (CB[n]), the efficacy of PDT agents is significantly inhibited. By contrast, in the presence of ROS (H2O2) and pro-guest, PDT agents are displaced and reactivated to show a dramatically enhanced PDT efficacy in cells.
We report the Lewis acid catalysis of aryldiazonium salts, and their Lewis acidity applications in photogeneration of aryl radicals under additive-, photocatalyst- and transition metal-free conditions. In this visible light-mediated transformation, the Lewis acidic character of aryldiazonium salts enables access to the photoactive charge transfer complex with dichalcogenides. The usefulness and versatility of this new protocol are demonstrated through the chalcogenation of a variety of aryldiazonium salts.
The first assembly of a conjugation-ready hexasaccharide from the capsular glycan of C. jejuni. strain BH0142 has been accomplished. The synthesis features the efficient preparation of 6-deoxy-d-ido-heptopyranosyl fluoride donors proceeding from allyl α-d-C-glucopyranoside by a C1-to-C5 switch strategy with radical dehydroxymethylative fluorination as a key step, stereocontrolled construction of 1,2-trans-α-d-ido-heptopyranosidic bonds and of 1,2-cis-α-d-galactopyranosidic linkages. The obtained target oligosaccharide sets a solid foundation for making structurally-defined multivalent glycoconjugate vaccine candidates against C. jejuni. infections.
Herein, we report the first atroposelective C(sp2)–H bond acyloxylation enabled by a phosphine oxide directing group. Uniquely, this transformation is shown to proceed through an eight-membered palladacycle intermediate, as opposed to the kinetically and thermodynamically favored five-membered palladacycle intermediate. Additionally, L-pGlu-OH, a cheap and abundant chiral amino acid derivative, was identified as the best chiral ligand to promote this atroposelective remote CH functionalization reaction.
Separators is indispensable for the normal operation of lithium-ion batteries (LIBs). However, the widely used commercial polyolefin separators have some inherent deficiencies such as poor thermotolerance, high inflammability and inferior electrolyte wettability, which restrict their further applications of the advanced and safe batteries. Herein, we design a novel thermotolerant (a shrinkage percentage of 0% at 300 ℃) and flame retarded aerogel separator consisting of aramid nanofibers (ANFs). Because of its high porosity (86.5% ± 6.1%) and excellent electrolyte uptake (695%), the ANFs aerogel separator has an ionic conductivity of 1.04 mS/cm and a high lithium-ion transference number (0.67), which can endow LIBs with outstanding rate performance and superior cycling performance. Specifically, the ANFs aerogel separator-based batteries possess a discharge specific capacity of 102 mAh/g with a capacity retention of 90.7% and a Coulombic efficiency of 99.3% after 600 cycles at 5 C. In addition, under an operated temperature of 90 ℃, the battery with ANFs aerogel separator can still conduct the very steady charge-discharge, presenting a capacity retention of 90.1% and a Coulombic efficiency of 99.6% after 200 cycles at 3 C. Accordingly, the separator can probably serve as a potential candidate for application to advanced and safe LIBs.
Heme proteins play various important roles in a variety of physiological and pathological processes. Surfactant assemblies have drawn great attention in fabricating fluorescent sensors to detect and identify proteins. In this study, an acetylpyrene fluorophore containing imidazole HP-1 was synthesized, and it could be well modulated by an anionic surfactant sodium dodecyl sulfate (SDS). The selected ensemble based on HP-1/SDS assemblies exhibited selective fluorescence sensing performance towards the heme proteins, including neuroglobin (Ngb), myoglobin (Mb) and cytochrome c (Cyt c). Besides, phospholipid DMPC vesicles as membrane models were particularly explored the association process between the heme protein Mb and membrane. The present work showed that Mb induced the lysis of DMPC liposomes visualized by transmission electron microscopy and optical microscope.
Metal-free carbon catalysts with excellent conduction performance have drawn much research attention in reduction reactions. Herein, a N, B co-doped carbon catalyst with high pyrrolic N proportion (35.75%) and excellent surface area (1409 m2/g) was successfully prepared via carbonizing covalent organic framework materials (COFs) containing N and B atoms assisted by ZnCl2 molten salt. The presence of ZnCl2 maintains the micropore structure of COFs to provide high specific surface areas and abundant lattice defects for carbon materials. In addition, electron-withdrawing B heteroatom further facilitates the formation of pyrrolic N at defect sites by modifying the electronic structure of carbon network. The tuning of surface areas and active N species in carbon catalysts successfully improve the selective hydrogenation of nitrobenzene to aniline. The optimized carbon material exhibits excellent nitrobenzene conversion (99.9%) and aniline selectivity (> 99%) within 15 min, as well as excellent substrate suitability. This work provides a certain guiding for the design and application of metal-free catalysis.
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