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A new Brønsted acid-catalyzed oxo-cyclization of propargyl alcohols with azlactones to synthesize C 2 -azlactonized 2 H -chromenes has been established that uses 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (BiNPO 4 H) as the catalyst and gives excellent diastereoselectivities (≥19:1 dr) in most cases. This protocol has a high compatibility with various substituents of substrates, offering a catalytic and useful entry to the fabrication of the synthetically important C 2 -functionalized 2 H -chromene scaffold.

Owing to the sharp edge-enhanced electric field, gold triangular nanoplates (AuNPLs) exhibit strong localized surface plasmon resonance (LSPR) scattering and display as red spots with high intensity and narrow distribution under dark-field microscopy (DFM), based on which sensitive sensing applications could be developed. As a concept of proof, the inhibition effects of pyrophosphate (PPi) against the etching of AuNPLs based on Cu 2+ and I - mediated is dynamically monitored. The etching proceeding of AuNPLs by copper ions and iodide ions leads to the gradually blue-shifted LSPR scattering color of AuNPLs under DFM from the original red to green, accompanied by the reduced LSPR scattering intensity. As a result of the strong affinity of PPi to copper ions, the presence of PPi makes the etching process greatly suppressed, thereby achieving sensitive detection of the PPi.

Investigating a reaction that is inconspicuously weak, slow, or coexists with other fast reactions is interesting since that can supply a capability to find new reactions or explore indecisive mechanisms, but the strategies for the investigations are still greatly limited. Herein, we apply the strategy of "finding from the data" to discuss inconspicuous reactions through improving the confidence level of detected signals. In dark-field microscopy (DFM) imaging analysis, plasmonic nanoprobes, such as silver nanoparticles (AgNPs), have been applied at a single nanoparticle level with high sensitivity, but correspondingly, the deviations caused by instrumental and operational errors are inevitable. Thus, silver shell-isolated nanoparticles (AgSHINs) as an internal reference (IR) are introduced to calibrate the scattering signals of AgNPs probe during the reactions. Two calibration factors, α and β, are used to calibrate the plasmonic scattering intensity and RGB values of the AgNPs probe of the DFM images, respectively, making the confidence level of the DFM imaging analysis greatly improved and, thus, supplying a possibility to monitor inconspicuously weak or slow reactions. As a proof of concept, the inconspicuous amalgamation of AgNP probes bathed in dilute solution of mercury higher than 1.0 × 10 -10 mol/L was successfully monitored. In the same way, we identified the very weak oxidation process of AgNP probes by dissolved oxygen in water. These successful monitorings of inconspicuous weak or slow reactions, which might be possible to be regarded as detection deviations mistakenly, show that the use of AgSHINs as an IR can provide a precise method to discern or discover inconspicuous slow reactions in nature through the DFM imaging analysis.

Under solvothermal/surfactant-thermal conditions, two new open-framework borogermanate and galloborate, centrosymmetric (Hdima) 2 [Ge 5 B 3 O 15 (OH)] (1; dima = dimethylamine) and noncentrosymmetric Na 4 Ga 3 B 4 O 12 (OH) (2), were obtained and characterized. Compound 1 contains an unusual basket-shaped Ge 5 B 3 O 18 (OH) cluster and displays a 3D open-framework layered structure. Compound 2 shows an interrupted 3,4-connected network constructed by alternately linked BO 3 units and Ga 3+ ions and displays weak second-harmonic-generation response.

The quality of dissolved organic matter (DOM) in a wet weather overflow (WWF) can be broadly influenced by anthropogenic factors, such as nonpoint sources of paved runoff and point sources of sanitary sewage within the drainage networks. This study focused on the anthropogenic influences of the paved runoff and sanitary sewage on the DOM quality of WWF using excitation-emission matrix parallel factor analysis (EEM-PARAFAC). Results show that (1) EEM-PARAFAC fitted terrestrial humic-like, anthropogenic humic-like, tryptophan-like, and tyrosine-like components can be regarded as indicators to identify the types of sewage overflows and the illicit connection status of drainage systems. (2) A short emission wavelength (em: 302-313 nm) peak of the tyrosine-like component occurred in the reserved sanitary sewage, while a type of longer emission wavelength (em: 321-325 nm) peak came from the sump deposit. These tyrosine-like components were gradually evacuated in the initial phase of the overflow process with the fading of their EEM signals. Fluorescence signal transformations of all the components confirmed the potential ability of EEM-PARAFAC to monitor the dynamic changes of the primary pollutant sources. (3) The input of the newly increased sanitary sewage had a dominant influence on the quality and yield of the WWF DOM.

Although siRNA techniques have been broadly applied as a tool for gene knockdown, substantial challenges remain in achieving efficient delivery and in vivo efficacy. In particular, the low efficiency of target gene silencing in vivo is a critical limiting step to the clinical application of siRNA therapies. Poly(amidoamine) (PAMAM) dendrimers are widely used as carriers for drug and gene delivery; however, in vivo siRNA delivery by PAMAM dendrimers remains to be carefully investigated. In this study, the effectiveness of G5 and G6 PAMAM dendrimers with 8% of their surface amines conjugated to MPEG-5000 was studied for siRNA delivery in vitro and for intramuscular in vivo delivery in mice. The results from the PEG-modified dendrimers were compared to the results from the parent dendrimers as well as Lipofectamine 2000 and INTERFERin. Both PEG-modifed dendrimers protect the siRNA from being digested by RNase and gave high transfection efficiency for FITC-labeled siRNA in the primary vascular smooth muscle cells (VSMC) and mouse peritoneal macrophages. The PEG-modified dendrimers achieved knockdown of both plasmid (293A cells) and adenovirus-mediated green fluorescence protein (GFP) expression (Cos7 cells) in vitro with efficiency similar to that shown for Lipofectamine 2000. We further demonstrated in vivo that intramuscular delivery of GFP-siRNA using PEG-modified dendrimer significantly suppressed GFP expression in both transiently adenovirus infected C57BL/6 mice and GFP transgenic mice.

Previous work with Xenopus egg extracts suggested that a wortmannin-sensitive protein phosphorylation event precedes both the removal of modified termini from DNA double-strand break ends and the joining of unmodified ends. To assess the possible role of DNA-dependent protein kinase in effecting this phosphorylation, both DNA end-joining and DNA-stimulated phosphorylation were examined in the presence of various inhibitors. Linear but not supercoiled DNA stimulated the phosphorylation of several endogenous proteins in the extracts, including species of approximately 48, 87, and 96 kDa. This phosphorylation was selectively suppressed by the kinase inhibitors wortmannin, dimethylaminopurine, and LY294002, with a dose response that in each case paralleled the inhibition of DNA end-joining. If wortmannin was added while the end-joining reaction was in progress, end-joining of DNA already present in the reaction continued for some time, but newly added DNA was not joined or processed at all. Ends with 3'-hydroxyl termini were joined much faster than those with 3'-phosphoglycolate termini, although both were equally effective in stimulating protein phosphorylation. The results support a role for DNA-dependent protein kinase in regulating end-joining in vitro, and suggest that at least one of the necessary phosphorylations involves a protein bound at or near the DNA end to be joined. In contrast, nuclear extracts from human cells joined double-strand breaks with normal but not modified termini, and the joining was unaffected by kinase inhibitors, suggesting that the dominant mechanism of end-joining in these extracts did not involve DNA-PK.