Bridging the Gap: Electron Relay and Plasmonic Sensitization of Metal Nanocrystals for Metal Clusters

In recent years, enormous attention has been paid to the construction of metal cluster-semiconductor nanocomposites because of the fascinating and unique properties of metal clusters; however, investigations on photoelectrochemical (PEC) and photocatalytic properties of metal cluster-semiconductor systems are still rare. Moreover, to date, intrinsic correlation between metal clusters and bulk metal nanocrystals has yet to be elucidated. In this work, a facile layer-by-layer (LbL) self-assembly strategy has been developed to judiciously and intimately integrate gold nanocrystals (Au) within the interface between gold clusters (Au_<i>x</i>) and hierarchically ordered TiO₂ nanotube arrays framework, by which imperative roles of Au nanocrystals as electron relay mediator and plasmonic sensitizer for Au_<i>x</i> clusters were revealed. In addition, it was found that synergistic interaction between Au nanocrystals and Au_<i>x</i> clusters contributed to promising visible-light-driven photocatalytical and PEC performances. It is anticipated that our work could provide a general way for rationally constructing metal and metal clusters codecorated semiconductor heterostructures and, more significantly, bridge the gap between metal clusters and metal nanocrystals for a diverse range of applications

Biocompatible, Free-Standing Film Composed of Bacterial Cellulose Nanofibers–Graphene Composite

In recent years, graphene films have been used in a series of wide applications in the biomedical area, because of several advantageous characteristics. Currently, these films are derived from graphene oxide (GO) via chemical or physical reduction methods, which results in a significant decrease in surface hydrophilicity, although the electrical property could be greatly improved, because of the reduction process. Hence, the comprehensive performance of the graphene films showed practical limitations in the biomedical field, because of incompatibility of highly hydrophobic surfaces to support cell adhesion and growth. In this work, we present a novel fabrication of bacterial cellulose nanofibers/reduced graphene oxide (BC-RGO) film, using a bacterial reduction method. Thus-prepared BC-RGO films maintained excellent hydrophilicity, while electrical properties were improved by bacterial reduction of GO films in culture. Human marrow mesenchymal stem cells (hMSCs) cultured on these surfaces showed improved cellular response with higher cell proliferation on the BC-RGO film, compared to free-standing reduced graphene oxide film without the nanoscale fibrous structure. Furthermore, the cellular adhesion and proliferation were even comparable to that on the tissue culture plate, indicating that the bacterial cellulose nanofibers play a critically contructive role in supporting cellular activities. The novel fabrication method greatly enhanced the biochemical activity of the cells on the surface, which could aid in realizing several potential applications of graphene film in biomedical area, such as tissue engineering, bacterial devices, etc

Efficient and Rapid Hydrogen Extraction from Ammonia–Water <i>via</i> Laser Under Ambient Conditions without Catalyst

As a good carrier of hydrogen, ammonia–water has been employed to extract hydrogen in many ways. Here, we demonstrate a simple, green, ultrafast, and highly efficient method for hydrogen extraction from ammonia–water by laser bubbling in liquids (LBL) at room temperature and ambient pressure without catalyst. A maximum apparent yield of 33.7 mmol/h and a real yield of 93.6 mol/h were realized in a small operating space, which were far higher than the yields of most hydrogen evolution reactions from ammonia–water under ambient conditions. We also established that laser-induced cavitation bubbles generated a transient high temperature, which enabled a very suitable environment for hydrogen extraction from ammonia–water. The laser used here can serve as a demonstration of potentially solar-pumped catalyst-free hydrogen extraction and other chemical synthesis. We anticipate that the LBL technique will open unprecedented opportunities to produce chemicals

Efficient and Rapid Hydrogen Extraction from Ammonia–Water <i>via</i> Laser Under Ambient Conditions without Catalyst

As a good carrier of hydrogen, ammonia–water has been employed to extract hydrogen in many ways. Here, we demonstrate a simple, green, ultrafast, and highly efficient method for hydrogen extraction from ammonia–water by laser bubbling in liquids (LBL) at room temperature and ambient pressure without catalyst. A maximum apparent yield of 33.7 mmol/h and a real yield of 93.6 mol/h were realized in a small operating space, which were far higher than the yields of most hydrogen evolution reactions from ammonia–water under ambient conditions. We also established that laser-induced cavitation bubbles generated a transient high temperature, which enabled a very suitable environment for hydrogen extraction from ammonia–water. The laser used here can serve as a demonstration of potentially solar-pumped catalyst-free hydrogen extraction and other chemical synthesis. We anticipate that the LBL technique will open unprecedented opportunities to produce chemicals

Light-Induced In Situ Transformation of Metal Clusters to Metal Nanocrystals for Photocatalysis

In situ transformation of glutathione-capped gold (Au_<i>x</i>) clusters to gold (Au) nanocrystals under simulated solar light irradiation was achieved and utilized as a facile synthetic approach to rationally fabricate Au_<i>x</i>/Au/TiO₂ ternary and Au/TiO₂ binary heterostructures. Synergistic interaction of Au_<i>x</i> clusters and Au nanocrystals contributes to enhanced visible-light-driven photocatalysis

Development of a Reversibly Switchable Fluorescent Protein for Super-Resolution Optical Fluctuation Imaging (SOFI)

Reversibly switchable fluorescent proteins (RSFPs) can be effectively used for super-resolution optical fluctuation imaging (SOFI) based on the switching and fluctuation of single molecules. Several properties of RSFPs strongly influence the quality of SOFI images. These properties include (i) the averaged fluorescence intensity in the fluctuation state, (ii) the on/off contrast ratio, (iii) the photostability, and (iv) the oligomerization tendency. The first three properties determine the fluctuation range of the imaged pixels and the SOFI signal, which are of essential importance to the spatial resolution, and the last may lead to artificial aggregation of target proteins. The RSFPs that are currently used for SOFI are low in averaged fluorescence intensity in the fluctuation state, photostability, and on/off contrast ratio, thereby limiting the range of application of SOFI in biological super-resolution imaging. In this study, we developed a novel monomeric green RSFP termed Skylan-S, which features very high photostability, contrast ratio, and averaged fluorescence intensity in the fluctuation state. Taking advantage of the excellent optical properties of Skylan-S, a 4-fold improvement in the fluctuation range of the imaged pixels and higher SOFI resolution can be obtained compared with Dronpa. Furthermore, super-resolution imaging of the actin or tubulin structures and clathrin-coated pits (CCPs) in living U2OS cells labeled with Skylan-S was demonstrated using the SOFI technique. Overall, Skylan-S developed with outstanding photochemical properties is promising for long-time SOFI imaging with high spatial-temporal resolution

Double Role of the Hydroxy Group of Phosphoryl in Palladium(II)-Catalyzed <i>ortho</i>-Olefination: A Combined Experimental and Theoretical Investigation

Density functional theory calculations have been carried out on Pd-catalyzed phosphoryl-directed <i>ortho</i>-olefination to probe the origin of the significant reactivity difference between methyl hydrogen benzylphosphonates and dimethyl benzylphosphonates. The overall catalytic cycle is found to include four basic steps: C–H bond activation, transmetalation, reductive elimination, and recycling of catalyst, each of which is constituted from different steps. Our calculations reveal that the hydroxy group of phosphoryl plays a crucial role almost in all steps, which can not only stabilize the intermediates and transition states by intramolecular hydrogen bonds but also act as a proton donor so that the η¹-CH₃COO^– ligand could be protonated to form a neutral acetic acid for easy removal. These findings explain why only the methyl hydrogen benzylphosphonates and methyl hydrogen phenylphosphates were found to be suitable reaction partners. Our mechanistic findings are further supported by theoretical prediction of Pd-catalyzed <i>ortho</i>-olefination using methyl hydrogen phenylphosphonate, which is verified by experimental observations that the desired product was formed in a moderate yield

Evaluation of UDCA and its derivatives effects on different cell lines.

<p>The growth ratio of UDCA and its 20 different derivatives on (<b>A</b>) SMMC-7721, (<b>B</b>) HepG2, and (<b>C</b>) QSG-7701 were detected by MTT assay. (A–C shows the ratios relative to untreated controls). All compounds were administered at concentrations under 100 µM and allowed to incubate for 24 h. (<b>D</b>) QSG-7701 cells were either untreated or pretreated with 100 µM UDCA and U12 for 18 h. The cultures were replaced with 300 µM DCA and allowed to incubate for 6 h and then an MTT assay was performed to assess the ability of UDCA and U12 to rescue cytotoxicity induced by DCA. Results are representative of three independent experiments, showing mean±SD (α, <i>P</i><0.05, compared with UDCA treatment).</p

Additional file 3 of Nuclear receptor RXRα binds the precursor of miR-103 to inhibit its maturation

Additional file 3. Original western blot and Coomassie blue protein staining data

Seven of the top 20 predictive pathways were found to be associated with U12-induced cell cycle regulation on SMMC-7721 cells.

<p>Seven of the top 20 predictive pathways were found to be associated with U12-induced cell cycle regulation on SMMC-7721 cells.</p