Robertskamper4308

A new intramolecular oxidative amino-hydroxylation of o-allenyl anilines is reported. Treatment of carbamate-protected anilines with lead(IV) carboxylates in dichloromethane at room temperature results in facile tandem C-N (allene cyclization) and C-O bond formation (carboxylate trapping) to form indole products. Detailed reaction scope, mechanistic and kinetic studies suggest a reaction pathway involving an initial Wessely dearomatization step followed by cyclization and rearomatization.Eight new complex flavanones with a novel linkage, cryptoyunnanones A-H (1-8), together with four known α-pyrones, were isolated from the leaves and twigs of Cryptocarya yunnanensis. The structures of 1-8 including their absolute configurations were characterized by spectroscopic data analysis and single-crystal X-ray crystallography. Plausible biosynthetic pathways for the formation of compounds 1-8 were proposed. Compounds 1-4 exhibited cytotoxicity against HCT-116, MDA-MB-231, and PC-3 cancer cells with IC50 values from 6.4 to 9.1 μM.The connection between electronic structures of metal-organic frameworks (MOFs) and their building subunits is a key cornerstone for rational MOF material design. Some two-dimensional conjugated MOFs were reported to be topological insulators. However, many of them are not intrinsic as the Fermi levels are far from the topological gaps. The subunit-to-MOF electronic orbital correspondence should be established to bridge their chemical structure and physical properties, thus understanding the design rules toward intrinsic topological insulators. Herein we reveal the fundamental role of the subunit-to-MOF symmetry relation in determining their orbital interaction and hybridization and, consequently, topological characteristics. In particular, such honeycomb-kagome MOFs possess delocalized symmetry-enforced nonbonding electronic states with the topological spin-orbit gap. The nonbonding nature of these states allows tailored band structure modulation through molecular structure and strain engineering, with the potential realization of an intrinsic metal-organic topological insulator.The mononuclear complexes ([(bztpen)Cu] (BF4)2 (bztpen = N-benzyl-N,N',N'-tris (pyridin-2-yl methyl ethylenediamine))) and ([(dbzbpen)Cu(OH2)] (BF4)2 (dbzbpen = N,N'-dibenzyl-N,N'-bis(pyridin-2-ylmethyl) ethylenediamine)) have been reported as water oxidation catalysts in basic medium (pH = 11.5). We explore the O2 evolution process catalyzed by these copper catalysts with various ligands (L) by applying the first-principles molecular dynamics simulations. First, the oxidation of catalysts to the metal-oxo intermediates [LCu(O)]2+ occurs through the proton-coupled electron transfer (PCET) process. These intermediates are involved in the oxygen-oxygen bond formation through the water-nucleophilic addition process. Here, we have considered two types of oxygen-oxygen bond formation. The first one is the transfer of the hydroxide of the water molecule to the Cu═O moiety; the proton transfer to the solvent leads to the formation of the peroxide complex ([LCu(OOH)]+). The other is the formation of the hydrogen pero the rate-determining step. We calculated the rates of reaction by using the Eyring equation and found them to be close to the experimental values.Research related to the development and application of luminescent nanoparticles (LNPs) for chemical and biological analysis and imaging is flourishing. Novel materials and new applications continue to be reported after two decades of research. This review provides a comprehensive and heuristic overview of this field. It is targeted to both newcomers and experts who are interested in a critical assessment of LNP materials, their properties, strengths and weaknesses, and prospective applications. Numerous LNP materials are cataloged by fundamental descriptions of their chemical identities and physical morphology, quantitative photoluminescence (PL) properties, PL mechanisms, and surface chemistry. These materials include various semiconductor quantum dots, carbon nanotubes, graphene derivatives, carbon dots, nanodiamonds, luminescent metal nanoclusters, lanthanide-doped upconversion nanoparticles and downshifting nanoparticles, triplet-triplet annihilation nanoparticles, persistent-luminescence nanoparticles, conjugated polymer nanoparticles and semiconducting polymer dots, multi-nanoparticle assemblies, and doped and labeled nanoparticles, including but not limited to those based on polymers and silica. As an exercise in the critical assessment of LNP properties, these materials are ranked by several application-related functional criteria. Additional sections highlight recent examples of advances in chemical and biological analysis, point-of-care diagnostics, and cellular, tissue, and in vivo imaging and theranostics. These examples are drawn from the recent literature and organized by both LNP material and the particular properties that are leveraged to an advantage. Finally, a perspective on what comes next for the field is offered.The global rise and spread of antibiotic resistance greatly challenge the treatment of bacterial infections. Wastewater treatment plants (WWTPs) harbor and discharge antibiotic resistance genes (ARGs) as environmental contaminants. However, the knowledge gap on the host identity, activity, and functionality of ARGs limits transmission and health risk assessment of the WWTP resistome. click here Hereby, a genome-centric quantitative metatranscriptomic approach was exploited to realize high-resolution qualitative and quantitative analyses of bacterial hosts of ARGs (i.e., multiresistance, pathogenicity, activity, and niches) in the 12 urban WWTPs. We found that ∼45% of 248 recovered genomes expressed ARGs against multiple classes of antibiotics, among which bacitracin and aminoglycoside resistance genes in Proteobacteria were the most prevalent scenario. Both potential pathogens and indigenous denitrifying bacteria were transcriptionally active hosts of ARGs. The almost unchanged relative expression levels of ARGs in the most resistant populations (66.9%) and the surviving ARG hosts including globally emerging pathogens (e.g., Aliarcobacter cryaerophilus) in treated WWTP effluent prioritize future examination on the health risks related to resistance propagation and human exposure in the receiving environment.(-)-α-Bisabolol is a functional ingredient in various health and cosmetic products and has antibacterial, anti-inflammatory, and wound healing properties. (-)-α-Bisabolol is chemically synthesized and produced by steam distillation of essential oils extracted from Brazilian Candeia (Eremanthus erythropappus). To sustainably produce pure (-)-α-bisabolol, we previously engineered Escherichia coli to produce 9.1 g/L (-)-α-bisabolol via heterologous mevalonate pathways and (-)-α-bisabolol synthase (BOS) from German chamomile, Matricaria recutita (MrBOS). BOS has only been reported in MrBOS and Brazilian Candeia (EeBOS). The limited availability of BOS has made it difficult to achieve high titer and yield and large-scale (-)-α-bisabolol production. We identified a novel BOS in globe artichoke (CcBOS) and examined its functionality in vitro and in vivo. CcBOS showed higher catalytic efficiency and (-)-α-bisabolol production rates than those from MrBOS or EeBOS. In fed-batch fermentation, CcBOS generated the highest reported (-)-α-bisabolol titer to date (23.4 g/L). These results may facilitate economically viable industrial (-)-α-bisabolol production.Transfection is based on nonviral delivery of nucleic acids or proteins into cells. Viral approaches are being used; nevertheless, their translational capacity is nowadays decreasing due to persistent fear of their safety, therefore creating space for the field of nanotechnology. However, nanomedical approaches introducing static nanoparticles for the delivery of biologically active molecules are very likely to be overshadowed by the vast potential of nanorobotics. We hereby present a rapid nonviral transfection of protein into a difficult-to-transfect prostate cancer cell line facilitated by chemically powered rectangular virus-sized (68 nm × 33 nm) nanorobots. link2 The enhanced diffusion of these biocompatible nanorobots is the key to their fast internalization into cells, happening in a matter of minutes and being up to 6-fold more efficient compared to static nanorobots in a nonfueled environment. The Au/Ag plasmonic nature of these nanorobots makes them simply traceable and allows for their detailed subcellular localization. Protein transfection mediated by such nanorobots is an important step forward, challenging the field of nanomedicine and having potential in future translational medical research.Glycosylation and fatty acid modification are promising strategies to improve peptide performance. We previously studied glycosylation and fatty acid modification of the anticancer peptide R-lycosin-I. In this study, we further investigated the co-modification of fatty acids and monosaccharides in R-lycosin-I. A glucose derivative was covalently coupled to the ε-amino group of the Lys residues of the lipopeptide R-C12, which was derived from R-lycosin-I modified with dodecanoic acid, and obtained seven glycolipid peptides. link3 They exhibited different cytotoxicity profiles, which may be related to the changes in physicochemical properties and binding ability to glucose transporter 1 (GLUT1). Among them, R-C12-4 exhibited the highest cytotoxicity and improved selectivity. A further study demonstrated that R-C12-4 showed significant cytotoxicity and antimetastasis activity in murine melanoma cells, melanoma spheroids, and animal models. Our results indicated that the glucose derivative modification position plays important roles in glucose-lipopeptide conjugates, and R-C12-4 might be a promising lead for developing anticancer drugs.We describe the modular design of a pseudorotaxane-based supramolecular pump and its photochemically driven autonomous nonequilibrium operation in a dissipative regime. These properties derive from careful engineering of the energy maxima and minima along the threading coordinate and their light-triggered modulation. Unlike its precursor, this second-generation system is amenable to functionalization for integration into more complex devices.The last decade has seen widespread adoption of triple quadrupole-based inductively coupled plasma-tandem mass spectrometry (ICPMS/MS) technique using a collision/reaction cell in combination with a precell bandpass mass analyzer to measure isotopes otherwise masked by spectral interferences. High-precision isotope ratio analysis containing such isotopes would benefit from a similar capability on a multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) platform, but using a quadrupole-based precell mass analyzer for MC-ICPMS/MS has several limitations. To overcome these limitations, we developed a novel precell mass analyzer for MC-ICPMS/MS using sector field technology. The new precell mass analyzer, comprising two Wien filters and a selection aperture, and a hexapole collision/reaction cell were integrated together in a single module and added to the commercially available Thermo Scientific Neptune XT MC-ICPMS to create a prototype MC-ICPMS/MS we named Vienna. Vienna was proven to retain the same performance of the base MC-ICPMS in terms of sensitivity, accuracy, and precision.