Stabilization and Induction of Oligonucleotide i‑Motif Structure <i>via</i> Graphene Quantum Dots

DNA i-motif structures have been found in telomeric, centromeric DNA and many in the promoter region of oncogenes; thus they might be attractive targets for gene-regulation processes and anticancer therapeutics. We demonstrate in this work that i-motif structures can be stabilized by graphene quantum dots (GQDs) under acidic conditions, and more importantly GQDs can promote the formation of the i-motif structure under alkaline or physiological conditions. We illustrate that the GQDs stabilize the i-motif structure through end-stacking of the bases at its loop regions, thus reducing its solvent-accessible area. Under physiological or alkaline conditions, the end-stacking of GQDs on the unfolded structure shifts the equilibrium between the i-motif and unfolded structure toward the i-motif structure, thus promoting its formation. The possibility of fine-tuning the stability of the i-motif and inducing its formation would make GQDs useful in gene regulation and oligonucleotide-based therapeutics

Natural light-micro aerobic condition for PSB wastewater treatment: a flexible, simple, and effective resource recovery wastewater treatment process

<p>Photosynthetic bacteria (PSB) have two sets of metabolic pathways. They can degrade pollutants through light metabolic under light-anaerobic or oxygen metabolic pathways under dark-aerobic conditions. Both metabolisms function under natural light-microaerobic condition, which demands less energy input. This work investigated the characteristics of PSB wastewater treatment process under that condition. Results showed that PSB had very strong adaptability to chemical oxygen demand (COD) concentration; with F/M of 5.2–248.5 mg-COD/mg-biomass, the biomass increased three times and COD removal reached above 91.5%. PSB had both advantages of oxygen metabolism in COD removal and light metabolism in resource recovery under natural light-microaerobic condition. For pollutants’ degradation, COD, total organic carbon, nitrogen, and phosphorus removal reached 96.2%, 91.0%, 70.5%, and 92.7%, respectively. For resource recovery, 74.2% of C in wastewater was transformed into biomass. Especially, coexistence of light and oxygen promote N recovery ratio to 70.9%, higher than with the other two conditions. Further, 93.7% of N-removed was synthesized into biomass. Finally, CO₂ emission reduced by 62.6% compared with the traditional process. PSB wastewater treatment under this condition is energy-saving, highly effective, and environment friendly, and can achieve pollution control and resource recovery.</p

Polyarylcyanation of Diyne: A One-Pot Three-Component Convenient Route for <i>In Situ</i> Generation of Polymers with AIE Characteristics

A facile, one-pot, three-component polymerization route for <i>in situ</i> generation of polymers with aggregation-induced emission (AIE) characteristics was developed. The polycoupling of dibromoarenes, internal diynes and potassium ferrocyanide was catalyzed by palladium acetate and sodium bicarbonate and proceeded smoothly in dimethylacetamide under nitrogen at 120 °C, producing poly­(triphenylacrylonitrite)­s (PTPANs) with high weight-average molecular weights of up to 223000 in high yields of up to 84%. This polymerization method enjoys the remarkable advantages of high reaction rate and efficiency and broad monomer scope. Model reaction was carried out to aid the structure characterization and property investigation of the obtained polymers. All the polymers show remarkable thermal stability, losing merely 5% of their weight at high temperature of up to 513 °C. They are soluble in common organic solvents and their spin-coated thin films exhibit high refractive indices (1.6482–1.7682). Thanks to the triphenylethene chromophore <i>in situ</i> generated during the polymerization, all the polymers are AIE-active and show strong light emission in the solid state. While UV irradiation of the polymer thin films in air through upper masks photo-oxidizes the exposed parts and quenches their light emission, the unexposed parts remain emissive. Two-dimensional fluorescent patterns with good resolution are thus generated

Polyarylcyanation of Diyne: A One-Pot Three-Component Convenient Route for <i>In Situ</i> Generation of Polymers with AIE Characteristics

A facile, one-pot, three-component polymerization route for <i>in situ</i> generation of polymers with aggregation-induced emission (AIE) characteristics was developed. The polycoupling of dibromoarenes, internal diynes and potassium ferrocyanide was catalyzed by palladium acetate and sodium bicarbonate and proceeded smoothly in dimethylacetamide under nitrogen at 120 °C, producing poly­(triphenylacrylonitrite)­s (PTPANs) with high weight-average molecular weights of up to 223000 in high yields of up to 84%. This polymerization method enjoys the remarkable advantages of high reaction rate and efficiency and broad monomer scope. Model reaction was carried out to aid the structure characterization and property investigation of the obtained polymers. All the polymers show remarkable thermal stability, losing merely 5% of their weight at high temperature of up to 513 °C. They are soluble in common organic solvents and their spin-coated thin films exhibit high refractive indices (1.6482–1.7682). Thanks to the triphenylethene chromophore <i>in situ</i> generated during the polymerization, all the polymers are AIE-active and show strong light emission in the solid state. While UV irradiation of the polymer thin films in air through upper masks photo-oxidizes the exposed parts and quenches their light emission, the unexposed parts remain emissive. Two-dimensional fluorescent patterns with good resolution are thus generated

Visualization of the Formation and 3D Porous Structure of Ag Doped MnO₂ Aerogel Monoliths with High Photocatalytic Activity

Owing to their intriguing properties, aerogels with rich and hierarchical pore systems are best appreciated in catalysis, sensing, and separation technologies. Herein, a comprehensive study is presented for inorganic monolithic aerogel of Ag doped MnO₂ (Ag-MnO₂), synthesized solely out of nanowires of diameter ∼10 nm. We demonstrated a 3D image of the full bulk structure of the aerogel using X-ray computed tomography (μCT), providing a concise and statistical description of its porous structure for the first time. Interestingly, a flow-through supermacroporous system was observed as a result of freeze-drying. Owing to the rich pore system, the Ag-MnO₂ aerogel monolith exhibited photocatalytic degradation of organic water pollutants, which was superior in performance as compared to that of the MnO₂ powder and compressed Ag-MnO₂ pellet. A detailed study of photocatalytic mechanism was also carried out, indicating that Ag can simultaneously modulate the physical and chemical properties of MnO₂. This work highlights the significance of porous system in monolith catalysts, and provides insight into design and prepare metal oxide aerogels for environmental and energy applications

Regorafenib inhibited gastric cancer cells growth and invasion via CXCR4 activated Wnt pathway

<div><p>Aim</p><p>Regorafenib is an oral small-molecule multi kinase inhibitor. Recently, several clinical trials have revealed that regorafenib has an anti-tumor activity in gastric cancer. However, only part of patients benefit from regorafenib, and the mechanisms of regorafenib’s anti-tumor effect need further demonstrating. In this study, we would assess the potential anti-tumor effects and the underlying mechanisms of regorafenib in gastric cancer cells, and explore novel biomarkers for patients selecting of regorafenib.</p><p>Methods</p><p>The anti-tumor effects of regorafenib on gastric cancer cells were analyzed via cell proliferation and invasion. The underlying mechanisms were demonstrated using molecular biology techniques.</p><p>Results</p><p>We found that regorafenib inhibited cell proliferation and invasion at the concentration of 20μmol/L and in a dose dependent manner. The anti-tumor effects of regorafenib related to the decreased expression of CXCR4, and elevated expression and activation of CXCR4 could reverse the inhibition effect of regorafenib on gastric cancer cells. Further studies revealed that regorafenib reduced the transcriptional activity of Wnt/β-Catenin pathway and led to decreased expression of Wnt pathway target genes, while overexpression and activation of CXCR4 could attenuate the inhibition effect of regorafenib on Wnt/β-Catenin pathway.</p><p>Conclusions</p><p>Our findings demonstrated that regorafenib effectively inhibited cell proliferation and invasion of gastric cancer cells via decreasing the expression of CXCR4 and further reducing the transcriptional activity of Wnt/β-Catenin pathway.</p></div

Enhancing Separation Abilities of “Low-Performance” Metal–Organic Framework Stationary Phases through Size Control

Peak broadening and peak tailing are common but rebarbative phenomena that always occur when using metal–organic frameworks (MOFs) as stationary phases. These phenomena result in diverse “low-performance” MOF stationary phases. Here, by adjusting the particle size of MOF stationary phases from microscale to nanoscale, we successfully enhance the separation abilities of these “low-performance” MOFs. Three zirconium-based MOFs (NU-1000, PCN-608, and PCN-222) with different organic ligands were synthesized with sizes of tens of micrometers and hundreds of nanometers, respectively. All the nanoscale MOFs exhibited exceedingly higher separation abilities than the respective microscale MOFs. The mechanism investigation proved that reducing the particle size can reduce the mass transfer resistance, thus enhancing the column efficiency by controlling the separation kinetics. Modulating the particle size of MOFs is an efficient way to enhance the separation capability of “low-performance” MOFs and to design high-performance MOF stationary phases

Membranes with Nanochannels Based on Pillar[6]arenes to Separate Xylenes

Membrane separation technology has been widely applied in material separation fields. However, it still has the disadvantage of poor selectivity at nanometer and sub-nanometer scales. Here, two kinds of pillar[6]arene with opposite charges were prepared by modification, and the aligned nanochannel composite membrane was successfully constructed by directional assembly on a negatively charged silicon interface. The precise sieving properties of aligned channels were studied using the xylene isomer as a model molecule. It has been proved that the aligned channel can better maintain the pore size close to the macrocyclic molecules, which is beneficial to realize the customized construction of the through-ordered nanochannel. The experimental results show that the aligned nanochannel can selectively transport xylene isomers, and the flux (J) values of o, m, and p-xylene were 9.2, 11.6, and 171.3 nM m–2 h–1, respectively. Finally, the separation and purification of mixed samples have been achieved. This method provides a strategy for constructing ordered nanochannels

Methylation of 21U RNAs Requires <i>C. elegans</i> HEN1 Ortholog HENN-1.

<p>A) HENN-1 is required for 21U RNA methylation. Endogenous (<i>xkSi1</i>) and germline-specific (<i>xkSi2</i>) expression of <i>henn-1::gfp</i> rescue 21U RNA methylation in <i>henn-1(tm4477)</i> mutant embryo. Total embryo RNA of the indicated genotypes was β-eliminated (βe +) or control treated (βe −) and probed for piRNA 21UR-4292. <i>prg-1(tm872)</i> lacks 21U RNAs and is included as a negative control. Below, ethidium bromide staining of 5.8S rRNA is shown. Additional 21U RNA northern blots are shown in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002617#pgen.1002617.s003" target="_blank">Figure S3A</a>. B) <i>C. elegans</i> miRNAs are unmethylated. Total embryo RNA was probed for miR-1. Variable intensity of 5.8S rRNA bands in embryo indicates unequal loading.</p