Copper-Catalyzed Oxidative Amination of sp³ C–H Bonds under Air: Synthesis of 1,3-Diarylated Imidazo[1,5‑<i>a</i>]pyridines

A copper­(II)-catalyzed tandem reaction between pyridine ketone and benzylamine was developed by using clean O₂ as an oxidant. This transformation proceeded via an efficient condensation–amination–oxidative dehydrogenation process, affording 1,3-diarylated imidazo­[1,5-<i>a</i>]­pyridines in excellent yields

Two-Way Gold Nanoparticle Label-Free Sensing of Specific Sequence and Small Molecule Targets Using Switchable Concatemers

A two-way colorimetric biosensor based on unmodified gold nanoparticles (GNPs) and a switchable double-stranded DNA (dsDNA) concatemer have been demonstrated. Two hairpin probes (H1 and H2) were first designed that provided the fuels to assemble the dsDNA concatemers <i>via</i> hybridization chain reaction (HCR). A functional hairpin (FH) was rationally designed to recognize the target sequences. All the hairpins contained a single-stranded DNA (ssDNA) loop and sticky end to prevent GNPs from salt-induced aggregation. In the presence of target sequence, the capture probe blocked in the FH recognizes the target to form a duplex DNA, which causes the release of the initiator probe by FH conformational change. This process then starts the alternate-opening of H1 and H2 through HCR, and dsDNA concatemers grow from the target sequence. As a result, unmodified GNPs undergo salt-induced aggregation because the formed dsDNA concatemers are stiffer and provide less stabilization. A light purple-to-blue color variation was observed in the bulk solution, termed the light-off sensing way. Furthermore, H1 ingeniously inserted an aptamer sequence to generate dsDNA concatemers with multiple small molecule binding sites. In the presence of small molecule targets, concatemers can be disassembled into mixtures with ssDNA sticky ends. A blue-to-purple reverse color variation was observed due to the regeneration of the ssDNA, termed the light-on way. The two-way biosensor can detect both nucleic acids and small molecule targets with one sensing device. This switchable sensing element is label-free, enzyme-free, and sophisticated-instrumentation-free. The detection limits of both targets were below nanomolar

Marine Biofouling Resistance of Polyurethane with Biodegradation and Hydrolyzation

We have prepared polyurethane with poly­(ε-caprolactone) (PCL) as the segments of the main chain and poly­(triisopropylsilyl acrylate) (PTIPSA) as the side chains by a combination of radical polymerization and a condensation reaction. Quartz crystal microbalance with dissipation studies show that polyurethane can degrade in the presence of enzyme and the degradation rate decreases with the PTIPSA content. Our studies also demonstrate that polyurethane is able to hydrolyze in artificial seawater and the hydrolysis rate increases as the PTIPSA content increases. Moreover, hydrolysis leads to a hydrophilic surface that is favorable to reduction of the frictional drag under dynamic conditions. Marine field tests reveal that polyurethane has good antifouling ability because polyurethane with a biodegradable PCL main chain and hydrolyzable PTIPSA side chains can form a self-renewal surface. Polyurethane was also used to carry and release a relatively environmentally friendly antifoulant, and the combined system exhibits a much higher antifouling performance even in a static marine environment

Synthesis of 1,3-Disubstituted Imidazo[1,5‑<i>a</i>]pyridines from Amino Acids via Catalytic Decarboxylative Intramolecular Cyclization

A copper/iodine cocatalyzed decarboxylative cyclization of α-amino acids is described. Starting from the readily available amino acids and either 2-benzoylpyridines or 2-benzoylquinolines, 1,3-disubstituted imidazo­[1,5-<i>a</i>]­pyridines and 1,3-disubstituted imidazo­[1,5-<i>a</i>]­quinolines were prepared in excellent yields

Biodegradable Polyurethane Carrying Antifoulants for Inhibition of Marine Biofouling

Biodegradable polyurethane with <i>N</i>-(2,4,6-trichlorophenyl)­maleimide (TCPM) pendant groups has been prepared via a combination of a thiol–ene click reaction and a condensation reaction. The TCPM moieties acting as antifoulants are released as the polyurethane degrades in the marine environment. The biodegradation and hydrolyzation of the polyurethane were investigated by use of quartz crystal microbalance with dissipation (QCM-D) and hydrolysis experiments. It shows both the enzymatic degradation rate and the hydrolyzation rate decrease with TCPM content, which facilitates increasing the duration of the polyurethane. Marine field tests reveal that the polyurethane has good antifouling ability since the degradation leads to a self-renewal surface and the release of the antifoulants is controlled

Controlled Growth of 1D MoSe₂ Nanoribbons with Spatially Modulated Edge States

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) possess interesting one-dimensional (1D) properties at its edges and inversion domain boundaries, where properties markedly different from the 2D basal plane, such as 1D metallicity and charge density waves, can be observed. Although 2D TMDCs crystals are widely grown by chemical vapor deposition (CVD), the fabrication of 1D TMDCs ribbons is challenging due to the difficulty to confine growth in only one dimension. Here we report the controlled growth of MoSe₂ nanoribbons with an aspect ratio >100 by using prepatterned Se reconstructions on Au(100). Using scanning tunneling microscope and spectroscopy (STM/STS), the atomic and electronic structure of MoSe₂ nanoribbons are studied. The ultranarrow ribbons show metallic behavior, while wider ribbons show a crossover from metallic to semiconducting behavior going from the edge to the center of the ribbon. The observed conductance modulations of the ultranarrow ribbons are attributed to 1D Moiré pattern. Remarkably, it shows a different periodicity compared with the 2D Moiré pattern in wider ribbons indicating that the 1D system is softened due to the high ratio of edge to basal plane bonds. Further, we demonstrated that the nanoribbons are stable against ambient conditions, which suggests that 1D TMDCs can be exploited for further applications

A Highly Sensitive and Selective Fluorescent Sensor for Detection of Al³⁺ Using a Europium(III) Quinolinecarboxylate

<b>Eu₂PQC</b>_<b>6</b> has been developed to detect Al³⁺ by monitoring the quenching of the europium-based emission, with the lowest detection limit of ∼32 pM and the quantitative detection range to 150 μM. <b>Eu₂PQC</b>_<b>6</b> is the first ever example that the europium­(III) complex serves as an Al³⁺ fluorescent sensor based on “competition-displacement” mode

Comparative Profiling of microRNA Expression in Soybean Seeds from Genetically Modified Plants and their Near-Isogenic Parental Lines

<div><p>MicroRNAs (miRNAs) have been widely demonstrated to play fundamental roles in gene regulation in most eukaryotes. To date, there has been no study describing the miRNA composition in genetically modified organisms (GMOs). In this study, small RNAs from dry seeds of two GM soybean lines and their parental cultivars were investigated using deep sequencing technology and bioinformatic approaches. As a result, several differentially expressed gma-miRNAs were found between the GM and non-GM soybeans. Meanwhile, more differentially expressed gma-miRNAs were identified between distantly relatednon-GM soybeans, indicating that the miRNA components of soybean seeds varied among different soybean lines, including the GM and non-GM soybeans, and the extent of difference might be related to their genetic relationship. Additionally, fourteen novel gma-miRNA candidates were predicted in soybean seeds including a potential bidirectionally transcribed miRNA family with two genomic loci (gma-miR-N1). Our findings firstly provided useful data for miRNA composition in edible GM crops and also provided valuable information for soybean miRNA research.</p></div

Optimization of the UP-M-PCR.

<p>Lane A, B, C, D, E, amplicon fragments by UP (500 nmol L⁻¹) and compound specific primer hpt-839, nptII-508, pat-262, bar-226 and sps-110 at a series concentrations of 500 nmol L⁻¹, 50 nmol L⁻¹, 25 nmol L⁻¹, 5 nmol L⁻¹, 0.5 nmol L⁻¹; lane F1, amplicon fragments by UP at 500 nmol L⁻¹ and all compound specific primers at 25 nmol L⁻¹; lane F2, amplicon fragments by UP at 500 nmol L⁻¹ and all compound specific primers at the optimized concentration; lane G1,G2,G3, amplicon fragments by all primers at the optimized concentration with <i>TaKaRa Taq</i>™, Phire™ Hot Start DNA polymerase, iProof™ High-Fidelity DNA polymerase; lane H1, amplicon fragments by all primers at the optimized concentration with Phire™ Hot Start DNA polymerase under the common amplification conditions; lane H2, amplicon fragments by all primers at the optimized concentration with Phire™ Hot Start DNA polymerase under the optimized amplification conditions; lane M, 100 bp DNA Marker.</p