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Alzheimer's disease (AD) is the most common representation of dementia, with brain pathological hallmarks of protein abnormal aggregation, such as with amyloid beta and tau protein. It is well established that posttranslational modifications on tau protein, particularly phosphorylation, increase the likelihood of its aggregation and subsequent formation of neurofibrillary tangles, another hallmark of AD. As additional misfolded proteins presumably exist distinctly in AD disease states, which would serve as potential source of AD biomarkers, we used limited proteolysis-coupled with mass spectrometry (LiP-MS) to probe protein structural changes. After optimizing the LiP-MS conditions, we further applied this method to human cerebrospinal fluid specimens collected from healthy control, mild cognitive impairment (MCI), and AD subject groups to characterize proteome-wide misfolding tendencies as a result of disease progression. The fully tryptic peptides embedding LiP sites were compared with the half-tryptic peptides generated from internal cleavage of the same region to determine any structural unfolding or misfolding. We discovered hundreds of significantly up- and down-regulated peptides associated with MCI and AD indicating their potential structural changes in AD progression. Moreover, we detected 53 structurally changed regions in 12 proteins with high confidence between the healthy control and disease groups, illustrating the functional relevance of these proteins with AD progression. These newly discovered conformational biomarker candidates establish valuable future directions for exploring the molecular mechanism of designing therapeutic targets for AD. [ABSTRACT FROM AUTHOR]

The ever-increasing demand for flexible and portable electronics has stimulated research and development in building advanced electrochemical energy devices which are lightweight, ultrathin, small in size, bendable, foldable, knittable, wearable, and/or stretchable. In such flexible and portable devices, semi-solid/solid electrolytes besides anodes and cathodes are the necessary components determining the energy/power performances. By serving as the ion transport channels, such semi-solid/solid electrolytes may be beneficial to resolving the issues of leakage, electrode corrosion, and metal electrode dendrite growth. In this paper, the fundamentals of semi-solid/solid electrolytes (e.g., chemical composition, ionic conductivity, electrochemical window, mechanical strength, thermal stability, and other attractive features), the electrode–electrolyte interfacial properties, and their relationships with the performance of various energy devices (e.g., supercapacitors, secondary ion batteries, metal–sulfur batteries, and metal–air batteries) are comprehensively reviewed in terms of materials synthesis and/or characterization, functional mechanisms, and device assembling for performance validation. The most recent advancements in improving the performance of electrochemical energy devices are summarized with focuses on analyzing the existing technical challenges (e.g., solid electrolyte interphase formation, metal electrode dendrite growth, polysulfide shuttle issue, electrolyte instability in half-open battery structure) and the strategies for overcoming these challenges through modification of semi-solid/solid electrolyte materials. Several possible directions for future research and development are proposed for going beyond existing technological bottlenecks and achieving desirable flexible and portable electrochemical energy devices to fulfill their practical applications. It is expected that this review may provide the readers with a comprehensive cross-technology understanding of the semi-solid/solid electrolytes for facilitating their current and future researches on the flexible and portable electrochemical energy devices. [ABSTRACT FROM AUTHOR]

Protein glycosylation, covalent attachment of carbohydrates to polypeptide chains, is a highly important post-translational modification involved in many essential physiological processes. Comprehensive site-specific and quantitative analysis is crucial for revealing the diverse functions and dynamics of glycosylation. To characterize intact glycopeptides, mass spectrometry (MS)-based glycoproteomics employs versatile fragmentation methods, among which electron-transfer/higher-energy collision dissociation (EThcD) has gained great popularity. However, the inherent limitation of EThcD in fragmenting low-charge ions has prevented its widespread applications. Furthermore, there is a need to develop a high-throughput strategy for comparative glycoproteomics with a large cohort of samples. Herein, we developed isobaric N,N-dimethyl leucine-derivatized ethylenediamine (DiLeuEN) tags to increase the charge states of glycopeptides, thereby improving the fragmentation efficiency and allowing for in-depth intact glycopeptide analysis, especially for sialoglycopeptides. Moreover, the unique reporter ions of DiLeuEN-labeled glycopeptides generated in tandem MS spectra enable relative quantification of up to four samples in a single analysis, which represents a new high-throughput method for quantitative glycoproteomics. [ABSTRACT FROM AUTHOR]

Metal ions are ubiquitous in nature and play significant roles in assembling functional materials in fields spanning chemistry, biology, and materials science. Metal–phenolic materials are assembled from phenolic components in the presence of metal ions through the formation of metal–organic complexes. Alkali, alkali-earth, transition, and noble metal ions as well as metalloids interacting with phenolic building blocks have been widely exploited to generate diverse hybrid materials. Despite extensive studies on the synthesis of metal–phenolic materials, a comprehensive summary of how metal ions guide the assembly of phenolic compounds is lacking. A fundamental understanding of the roles of metal ions in metal–phenolic materials engineering will facilitate the assembly of materials with specific and functional properties. In this review, we focus on the diversity and function of metal ions in metal–phenolic material engineering and emerging applications. Specifically, we discuss the range of underlying interactions, including (i) cation−π, (ii) coordination, (iii) redox, and (iv) dynamic covalent interactions, and highlight the wide range of material properties resulting from these interactions. Applications (e.g., biological, catalytic, and environmental) and perspectives of metal–phenolic materials are also highlighted. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ultrathin silica films have the potential to reach technological importance in electronics and catalysis. Several well-defined 2D-silica structures have been synthesized so far. The silica bilayer represents a 2D material with SiO2 stoichiometry. It consists of precisely two layers of tetrahedral [SiO4] building blocks, corner connected via oxygen bridges, thus forming a self-saturated silicon dioxide sheet with a thickness of ∼0.5 nm. Inspired by recent successful preparations and characterizations of these 2D-silica model systems, scientists now can forge novel concepts for realistic systems, particularly by atomic-scale studies with the most powerful and advanced surface science techniques and density functional theory calculations. This Review provides a solid introduction to these recent developments, breakthroughs, and implications on ultrathin 2D-silica films, including their atomic/electronic structures, chemical modifications, atom/molecule adsorptions, and catalytic reactivity properties, which can help to stimulate further investigations and understandings of these fundamentally important 2D materials. [ABSTRACT FROM AUTHOR]

As the [2Fe]H subsite models of [FeFe]-hydrogenases, a series of PNP-chelated and -bridged diiron dithiolate complexes 1a-f and 2a-f together with the three related monophosphine complexes 3a-c were prepared by the selective substitutions of the all-carbonyl complex Fe2(μ-pdt)(CO)6 (A, pdt = SCH2CH2CH2S) with aminodiphosphines (Ph2P)2NR (denoted as PNP) under different reaction conditions. The first UV irradiation of the toluene solutions of A with different PNP ligands (PNP = (Ph2P)2NR; R = (CH2)3Me, (CH2)3NMe2, (CH2)3Si(OEt)3, C6H5, C6H4OMe-p, C6H4CO2Me-p) readily afforded the target PNP-chelated complexes Fe2(μ-pdt)(CO)4{(κ²-Ph2P)2NR} (1a-f), while the reflux of xylene solutions of A with the aforementioned PNP ligands produced the PNP-bridged complexes Fe2(μ-pdt)(CO)4{(μ-Ph2P)2NR} (2a-f). Comparatively, treatments of A and one type of PNP ligand with N-aryl substituents R (R = C6H5, C6H4OMe-p, C6H4CO2Me-p) in MeCN at room temperature in the presence of the decarbonylating agent Me3NO·2H2O formed the unexpected monophosphine complexes Fe2(μ-pdt)(CO)5{κ¹-Ph2P(NHR)} (3a-c) and the minor chelated complexes 1d-f. All of the complexes 1a-f, 2a-f, and 3a-c have been characterized by elemental analysis, FT-IR, NMR spectroscopy, and particularly for 1a,b,d-f, 2b,d-f, and 3b by X-ray crystallography. Additionally, the electrochemical and electrocatalytic properties of complexes 1a and 2a as a pair of representative isomers have been evaluated and compared by cyclic voltammetry in MeCN as solvent in the absence and presence of HOAc as a proton source. [ABSTRACT FROM AUTHOR]

Hexakis(m-phenylene ethynylene) (m-PE) macrocycles 1-4, sharing the same hydrogen-bonding side chains but having backbones of different electronic properties, are designed to probe the effectiveness of multiple H-bonding interactions in enforcing columnar assemblies. ¹H NMR, absorption, fluorescence, and circular dichroism (CD) spectroscopy indicate that, compared with analogous macrocycles that self-associate based on aromatic stacking which is highly sensitive to the electronic nature of the macrocyclic backbones, macrocycles 1-4 all exhibit strong aggregation down to the micromolar (µM) concentrations in nonpolar solvents. Increasing solvent polarity quickly weakens aggregation. In THF and DMF, the macrocycles exist as free molecules. The observed solvent effects, along with the behavior of 5-F6 that cannot self-associate via H-bonding, confirm that H-bonding plays the dominating role in driving the self-association of 1-4. The backbone electronic nature does not change the self-assembling pattern common to 1-4. Fluorescence and CD spectra confirm that macrocycles 1-4 assemble anisotropically, forming helical stacks in which adjacent molecules undergo relative rotation to place individual benzene residues in the favorable offset fashion. Columnar alignment of 1-4 is confirmed by atomic force microscopy (AFM), which resolves single tubes consisting of stacked macrocycles. In addition, macrocycles with backbones of different electronic properties are found to undergo heteroassociation, forming hybrid nanotubes. This study has demonstrated the generality of enforcing the alignment of shape-persistent macrocycles, which represents an invaluable addition to the small number of known tubular stacks capable of accommodating structurally varied molecular components and provides self-assembling nanotubes with inner pores allowing ready structural and functional modification. [ABSTRACT FROM AUTHOR]

Coordination insertion polymerization is unsurpassed as a straightforward method for synthesis of high-value polyolefins by the copolymerization of ethylene and polar monomers, but poison effects of polar groups on the metal center result in a lack of fine control over the polymer architecture. Herein we reported a thermally stable dibenzobarrelene-derived α-diimine palladium catalyst for the precision synthesis of functionalized polyolefins by living copolymerization of ethylene and a variety of acrylate comonomers. The introduction of the bulky dibenzobarrelene backbone can improve migratory insertion selectivity of methyl acrylate (MA) in a 2,1-mode, thus preventing polar groups from poisoning palladium centers by stable five-membered palladacycle intermediates formed by 1,2-insertion of MA. In this living chain-walking catalyst system, the composition, molecular weight, and branching topology of the copolymer can be facilely tunable by simple variation of the ethylene pressure. [ABSTRACT FROM AUTHOR]

This Communication describes a new molecular design for the efficient synthesis of donor-acceptor, cove-edge graphene nanoribbons and their properties in solar cells. These nanoribbons are long (∼5 nm), atomically precise, and soluble. The design is based on the fusion of electron deficient perylene diimide oligomers with an electron rich alkoxy pyrene subunit. This strategy of alternating electron rich and electron poor units facilitates a visible light fusion reaction in >95% yield, whereas the cove-edge nature of these nanoribbons results in a high degree of twisting along the long axis. The rigidity of the backbone yields a sharp longest wavelength absorption edge. These nanoribbons are exceptional electron acceptors, and organic photovoltaics fabricated with the ribbons show efficiencies of ∼8% without optimization. [ABSTRACT FROM AUTHOR]

Low tolerability and tumor selectivity restricts many potent anticancer drugs including mertansine from wide clinical use. Here, glutathione-activatable hyaluronic acid-SS-mertansine prodrug (HA-SS-DM1) was designed and developed to achieve enhanced tolerability and targeted therapy of CD44+ human breast tumor xenografts. DM1 was readily conjugated to HA using 2-(2-pyridyldithio)-ethylamine as a linker. Notably, HA-SS-DM1 with a high DM1 content of 20 wt % had a mean size of ∼170 nm at concentrations above 0.2 mg/mL while transformed into unimers upon dilution to 0.04 mg/mL. HA-SS-DM1 exhibited a superior targetability to MCF-7 cancer cells with an exceptionally low IC50 of 0.13 μg DM1/mL. The pharmacokinetic studies displayed that Cy5-labeled HA-SS-DM1 had an elimination half-life of 2.12 h. Notably, HA-SS-DM1 displayed better tolerability with a maximum-tolerated dose 4-fold higher than free DM1. Cy5-labeled HA-SS-DM1 quickly accumulated in the MCF-7 tumor, the fluorescence intensity of which was maximized at 24 h post injection and kept strong in 48 h. The tumor Cy5 level reached 8.17%ID/g at 24 h. The therapeutic results demonstrated that HA-SS-DM1 effectively inhibited tumor growth at 800 μg DM1 equiv/kg while causing reduced side effects as compared to free DM1. Glutathione-cleavable HA-SS-DM1 prodrug with superior drug content, excellent targetability, enhanced tolerability, and easy large-scale synthesis appears to be a highly promising alternative to clinically used Trastuzumab emtansine (T-DM1) for targeted breast tumor therapy. [ABSTRACT FROM AUTHOR]

Development of an efficient hydrogen evolution reaction (HER) catalyst composed of earth-abundant elements is scientifically and technologically important for the water splitting associated with the conversion and storage of renewable energy. Herein we report a new class of Co-C-N complex bonded carbon (only 0.22 at% Co) for HER with a self-supported and three-dimensional porous structure that shows an unexpected catalytic activity with low overpotential (212 mV at 100 mA cm-2) and long-term stability, better than that of most traditional-metal catalysts. Experimental observations in combination with density functional theory calculations reveal that C and N hybrid coordination optimizes the charge distribution and enhances the electron transfer, which synergistically promotes the proton adsorption and reduction kinetics. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF), which has been used as an analogue of the silk-like proteins in studying the biomineralization process of calcium carbonate in vitro, shows a high preference for the formation of aragonite polymorph. In this study, Fe3+, which has been found with relatively high levels in the shells of marine mollusks, was introduced into the SF-regulated biomineralization system. The addition of Fe3+ into the SF aqueous solutions induced a conformational transition of SF from random coil to β-sheet. The promoted β-sheet structures provided Ca2+-binding sites for SF and, accordingly, enabled the formation of an amorphous calcium carbonate precursor. Such a precursor has an aligned parallel structure and acts as a template for the direct growth of aragonite. The corresponding aragonite products showed similar organic-inorganic hierarchical structure to nacre building in vivo as well as higher thermal stability compared with that of the other Fe3+-free aragonite products in terms of the polymorph. It is indicated that Fe3+ plays multiple roles in this nacre-mimetic biomineralization process. By examining the coeffect of SF and Fe3+ as multiple additives, this study has provided a deeper understanding on the valuable contribution of Fe3+ in the nacre-mimetic system, which could facilitate the fabrication of similar synthetic materials with good mechanical performance from cheap abundant materials. [ABSTRACT FROM AUTHOR]

A polyimide microfluidic chip with a microhole emitter (Ø 10-12 μm) created on top of a microchannel by scanning laser ablation has been designed for nanoelectrospray ionization (spyhole-nanoESI) to couple microfluidics with mass spectrometry. The spyhole-nanoESI showed higher sensitivity compared to standard ESI and microESI from the end of the microchannel. The limits of detection (LOD) for peptide with the spyhole-nanoESI MS reached 50 pM, which was 600 times lower than that with standard ESI. The present microchip emitter allows the analysis of small volumes of samples. As an example, a small cell lung cancer biomarker, neuron-specific enolase (NSE), was detected by monitoring the transition of its unique peptide with the spyhole-nanoESI MS/MS. NSE at 0.2 nM could be well identified with a signal to noise ratio (S/N) of 50, and thereby its LOD was estimated to be 12 pM. The potential application of the spyhole-nanoESI MS/MS in cancer diagnosis was further demonstrated with the successful detection of 2 nM NSE from 1 μL of human serum. Before the detection, the serum sample spiked with NSE was first depleted with immune spin column, then desalted by centrifugal filter device, and finally digested by trypsin, without any other complicated preparation steps. The concentration matched the real condition of clinical samples. In addition, the microchips can be disposable to avoid any cross contamination. The present technique provides a highly efficient way to couple microfluidics with MS, which brings additional values to various microfluidics and MS-based analysis.ᅟ [ABSTRACT FROM AUTHOR]

3,3-Disubstituted oxindoles are widely distributed in natural products, drugs, and pharmaceutically active compounds. The absolute configuration and the substituents on the fully substituted C3 stereocenter of the oxindole often significantly influence the biological activity. Therefore, tremendous efforts have made to develop catalytic enantioselective syntheses of this prominent structural motif. Research in this area is further fueled by the ever-increasing demand for modern probe- and drug-discovery programs for synthetic libraries of chiral compounds that are derived from privileged scaffolds with high structural diversity. Notably, the efficient construction of fully substituted C3 stereocenters of oxindole, tetrasubstituted or all-carbon quaternary, spirocyclic or not, also becomes a test ground for new synthetic methodologies. We have been engaged in developing efficient methods for diversity-oriented synthesis of chiral 3,3-disubstituted oxindoles from readily available starting materials. We have systematically developed catalytic enantioselective methods to prepare 3-substituted 3-hydroxyoxindoles, 3-aminooxindoles, and 3-thiooxindoles, quaternary oxindoles, and spirocyclic oxindoles. These protocols can be classified into six approaches: (1) enantioselective addition of nucleophiles to isatins or isatin ketimines; (2) unprotected 3-substituted oxindoles as nucleophiles; (3) functionalization of oxindole-derived tetrasubstituted alkenes; (4) desymmetrization of oxindole-based diynes; (5) spirocyclopropyl oxindoles as donor-acceptor (D-A) cyclopropanes; and (6) elaboration of diazooxindoles. By the use of these methods, chiral oxindoles with rich structural diversity are readily accessed with high to excellent enantioselectivity. Some methods have been used for the enantioselective formal or total synthesis of natural products, bioactive compounds, or their analogues. On the basis of these studies, we developed synthetic methodologies that have potential application. We designed phosphoramide-based bifunctional catalysts for the efficient construction of quaternary oxindoles: a cinchona-alkaloid-derived phosphoramide for the Michael addition of unprotected 3-substituted oxindoles to nitroolefins with broad substrate scope and a chiral 1,2-cyclohexanediamine-derived bifunctional phosphoramide for the activation of fluorinated enol silyl ethers for the addition to isatylidene malononitrile. The phosphoramide-based catalysts achieved better enantiofacial control than the analogous H-bond-donor-derived catalysts in these reactions, suggesting the potential of the former in new chiral catalyst development. We identified chiral Au(I) and Hg(II) catalysts for olefin cyclopropanation of diazooxindoles. We further disclosed the effective activation of spirocyclopropyl oxindoles by using electron-withdrawing N-protecting groups for enantioselective [3 + 3] cycloaddition, offering the promise of constructing a diverse range of spirocyclic oxindoles by the use of such monoactivated D-A cyclopropanes. We developed tandem sequences that allow the facile synthesis of 3,3-disubstituted oxindoles from simple starting materials in a one-pot operation, including a tandem Morita-Baylis-Hillman/bromination/[3 + 2] annulation sequence, a hydrogenation/ketimine formation/asymmetric 6p electrocyclization sequence, a C-H functionalization/Michael addition or amination sequence, and an aza-Wittig/Strecker sequence. We designed oxindole-based diynes to realize a highly enantioselective Cu-catalyzed alkyne-azide cycloaddition (CuAAC), outlining the desymmetrization of prochiral diynes as an effective strategy to exploit asymmetric CuAAC. This Account focuses on the synthetic methodologies developed in our group for the catalytic enantioselective synthesis of 3,3-disubstituted oxindoles and provides an overview of our research on the design, development, and applications of these methods that will provide useful insights for the exploration of new reactions. [ABSTRACT FROM AUTHOR]

A novel and efficient photochemical method has been proposed for the encapsulation of Prussian blue nanoparticles (PBNPs) inside the channels of carbon nanotubes (PB-in-CNTs) in an acidic ferrocyanide solution under UV/vis illumination, and the confinement effect of CNTs on the electrochemical properties of PBNPs is systematically explored. PB-in-CNTs show a faster electron-transfer process, an enhanced electrocatalytic activity toward the reduction of H2O2, and an increased anti-base ability compared to PBNPs loaded outside of CNTs (PB-out-CNTs). In addition, PB-in-CNTs show an increased electrochemical reversibility and an unexpected diameter-independent catalytic activity with the decrease of CNT diameters. The improved electrochemical properties of PB-in-CNTs are attributed to the modified electronic properties and dimensions of PBNPs induced by the confinement effect of CNTs. This work provides further insights into the confinement effect on the properties of nanomaterials and will inspire extensive relevant investigations in the development of novel composites or excellent catalysts. [ABSTRACT FROM AUTHOR]

Monolayer valley semiconductors, such as tungsten diselenide (WSen2), possess valley pseudospin degrees of freedom that are optically addressable but degenerate in energy. Lifting the energy degeneracy by breaking time-reversal symmetry is vital for valley manipulation. This has been realized by directly applying magnetic fields or via pseudomagnetic fields generated by intense circularly polarized optical pulses. However, sweeping large magnetic fields is impractical for devices, and the pseudomagnetic fields are only effective in the presence of ultrafast laser pulses. The recent rise of two-dimensional (2D) magnets unlocks new approaches to controlling valley physics via van der Waals heterostructure engineering. Here, we demonstrate the wide continuous tuning of the valley polarization and valley Zeeman splitting with small changes in the laser-excitation power in heterostructures formed by monolayer WSe2 and 2D magnetic chromium triiodide (CrI3). The valley manipulation is realized via the optical control of the CrI3 magnetization, which tunes the magnetic exchange field over a range of 20 T. Our results reveal a convenient new path toward the optical control of valley pseudospins and van der Waals magnetic heterostructures. [ABSTRACT FROM AUTHOR]

Structure-property correlations are often hampered by insufficient structural insight into the crystal packing of polymer semiconductors widely used in electronic devices such as organic solar cells. Herein, both the semicrystalline morphology and the crystalline structures of two high performance polymer semiconductors showing more than 9% efficiencies, namely PDTBT-TT and PBT4T, are established by a combination of oriented crystallization and transmission electron microscopy. PDTBT-TT and PBT4T form layered structures with alternation of p-stacked backbones and layers of disordered alkyl side chains. π-Stacking is such that benzothiadiazole and the comonomer (quaterthiophene or thienothiophene-bithiophene) segregate to form distinct stacks. This segregated stacking is preferentially obtained in thin films aligned by high-temperature rubbing at T = 200-230 °C. However, the two polymers show different stabilities of this polymorph versus temperature. The segregated stacking of PDTBT-TT is stable up to near the melting temperature, whereas for PBT4T it transforms to a layered structure with significant intrastack disorder at T = 250 °C. The intensity of the 0-0 component of the vibronic progression in the absorption spectrum is enhanced for the polymorph with long-range segregated π-stacks. The structural models determined for the two polymers suggest that both the position of alkyl side chains and the preferential π-stacking interactions between comonomers determine the polymorphism and corresponding thermal stability. [ABSTRACT FROM AUTHOR]

Cloud/aerosol water surfaces exert significant influence over atmospheric chemical processes. Atmospheric processes at the water surface are observed to follow mechanisms that are quite different from those in the gas phase. This Account summarizes our recent findings of new reaction pathways on the water surface. We have studied these surface reactions using Born-Oppenheimer molecular dynamics simulations. These studies provide useful information on the reaction time scale, the underlying mechanism of surface reactions, and the dynamic behavior of the product formed on the aqueous surface. According to these studies, the aerosol water surfaces confine the atmospheric species into a specific orientation depending on the hydrophilicity of atmospheric species or the hydrogen-bonding interactions between atmospheric species and interfacial water. As a result, atmospheric species are activated toward a particular reaction on the aerosol water surface. For example, the simplest Criegee intermediate (CH2OO) exhibits high reactivity toward the interfacial water and hydrogen sulfide, with the reaction times being a few picoseconds, 2-3 orders of magnitude faster than that in the gas phase. The presence of interfacial water molecules induces proton-transfer-based stepwise pathways for these reactions, which are not possible in the gas phase. The strong hydrophobicity of methyl substituents in larger Criegee intermediates (>C1), such as CH3CHOO and (CH3)2COO, blocks the formation of the necessary prereaction complexes for the Criegee-water reaction to occur at the water droplet surface, which lowers their proton-transfer ability and hampers the reaction. The aerosol water surface provides a solvent medium for acids (e.g., HNO3 and HCOOH) to participate in reactions via mechanisms that are different from those in the gas and bulk aqueous phases. For example, the anti-CH3CHOO-HNO3 reaction in the gas phase follows a direct reaction between anti-CH3CHOO and HNO3, whereas on a water surface, the HNO3-mediated stepwise hydration of anti-CH3CHOO is dominantly observed. The high surface/volume ratio of interfacial water molecules at the aerosol water surface can significantly lower the energy barriers for the proton transfer reactions in the atmosphere. Such catalysis by the aerosol water surface is shown to cause the barrier-less formation of ammonium bisulfate from hydrated NH3 and SO3 molecules rather than from the reaction of H2SO4 with NH3. Finally, an aerosol water droplet is a polar solvent, which would favorably interact with high polarity substrates. This can accelerate interconversion of different conformers (e.g., anti and syn) of atmospheric species, such as glyoxal, depending on their polarity. The results discussed here enable an improved understanding of atmospheric processes on the aerosol water surface. [ABSTRACT FROM AUTHOR]

The stable solid-liquid phase equilibrium in the ternary system MgSO4 + MgCl2 + H2O at 263.15 K was investigated with the isothermal dissolution method, and the phase diagram was plotted. Two isothermal invariant points cosaturated with MgSO4·7H2O + ice and MgCl2·6H2O + MgSO4·7H2O, three stable crystallization fields corresponding to MgCl2·6H2O (Bis), MgSO4·7H2O (Eps), and ice, and three isothermal univariant curves were determined in the ternary system. Compared to the phase equilibrium at 273.15 K, the ice crystallization region and ice-salt invariant point are found at 263.15 K. Neither solid solution nor double salts are found in the system. [ABSTRACT FROM AUTHOR]

Multitarget assay with single detection modality from individual stimulation mode has aroused great attention. Here, we realize multitarget detection with the color change as signal source from single white light-emitting metal-organic frameworks (MOFs) under single wavelength excitation for the first time. The white light-emitting MOFs are prepared by carefully tuning the ratio of Eu3+, Tb3+, and Dy3+ ions to obtain trimetal MOFs; 5-boronoisophthalic acid (5-bop) provides additional selectivity as ligand. Based on antenna effect, 5-bop is excited to produce its triplet-state, which sensitizes the Ln3+ ions for the white emission. Thus, all of the fluorescence emission is achieved under single wavelength excitation at 275 nm, while any factors affecting the procedure result in the modulation of emission for diverse wavelengths. The trimetal MOFs display distinctive emission colors after interacting with different targets, including metal ions, anions, small molecule, and even biomolecule as a Lab-on-MOFs system. This system shows higher integration degree and simpler preparation and sensing procedures than other multitarget detection strategies. [ABSTRACT FROM AUTHOR]

Conformational isomerism plays a central role in organic synthesis and biological processes; however, effective control of isomerization processes still remains challenging and elusive. Here, we propose a novel paradigm for conformational control of isomerization in the condensed phase, in which the polarity of the solvent determines the relative concentration of conformers at the interfacial and bulk regions. By the use of state-of-the-art molecular dynamics simulations of glyoxal in different solvents, we demonstrate that the isomerization process is dipole driven: the solvent favors conformational changes toward conformers having molecular dipoles that better match its polar character. Thus, the solvent polarity modulates the conformational change, stabilizing and selectively segregating in the bulk vs the interface one conformer with respect to the others. The findings in this paper have broader implications affecting systems involving compounds with conformers of different polarity. This work suggests novel mechanisms for tuning the catalytic activity of surfaces in conformationally controlled (photo)chemical reactions and for designing a new class of molecular switches that are active in different solvent environments. [ABSTRACT FROM AUTHOR]

Molecular simulations of ionic liquids can provide deeper insight into the relationship between intermolecular interactions and macroscopic measurements for the solvents. However, many existing force fields have multiple shortcomings, including poor solvent dynamics, the underestimation of hydrogen-bonding strength, and errors in solvent interactions/organization. A new force field, called optimized potentials for liquid simulation-ionic-liquid virtual site (OPLS-VSIL), has been developed for imidazolium-based ionic liquids featuring a novel topology incorporating a virtual site bisecting the nitrogen atoms that offloads negative charge to inside the plane of the ring. Guided by free energy of hydration calculations, an empirically derived set of partial charges and nonbonded Lennard-Jones terms for both 1-alkyl-3-methylimidazolium and 11 different anions provided accurate bulk-phase ionic-liquid properties and produced radial distribution functions nearly indistinguishable from ab initio molecular dynamics simulations. For example, overall mean absolute errors (MAEs) of 3.1-3.4% were computed for the density, heat of vaporization, and viscosity of approximately 20 different ion pair combinations. Additional physical properties, such as, self-diffusion coefficients, heat capacity, and surface tension also gave significant MAE improvements using OPLS-VSIL compared to the existing fixed-charge ionic-liquid force fields. Local interactions, including cation-anion hydrogen bonding and π-π stacking between the imidazolium rings, were also accurately reproduced. [ABSTRACT FROM AUTHOR]

An asymmetric organocatalytic direct arylation approach to construct arylated quaternary stereogenic centers with a catalyst loading of 1 mol % is reported. The formation of the hemiketal moiety in stabilizing the hydroquinone intermediate proves to be important in leading to hydroquinone products instead of oxidation quinone products obtained in previously reported methods. A series of structurally and stereochemically complex heterocyclic frameworks are obtained, including spiro-, dispiro-, fused, and bridged heterocycles. [ABSTRACT FROM AUTHOR]

How to fine-tune the binding free energy of a small-molecule to a receptor site by altering the amino acid residue composition is a key question in protein engineering. Indeed, the ultimate solution to this problem, to chemical accuracy (±1 kcal/mol), will result in profound and wide-ranging applications in protein design. Numerous tools have been developed to address this question using knowledge-based models to more computationally intensive molecular dynamics simulations-based free energy calculations, but while some success has been achieved there remains room for improvement in terms of overall accuracy and in the speed of the methodology. Here we report a fast, knowledge-based movable-type (MT)-based approach to estimate the absolute and relative free energy of binding as influenced by mutations in a small-molecule binding site in a protein. We retrospectively validate our approach using mutagenesis data for retinoic acid binding to the Cellular Retinoic Acid Binding Protein II (CRABPII) system and then make prospective predictions that are borne out experimentally. The overall performance of our approach is supported by its success in identifying mutants that show high or even sub-nanomolar binding affinities of retinoic acid to the CRABPII system. [ABSTRACT FROM AUTHOR]

Group-V elemental monolayers were recently predicted to exhibit exotic physical properties such as nontrivial topological properties, or a quantum anomalous Hall effect, which would make them very suitable for applications in next-generation electronic devices. The free-standing group-V monolayer materials usually have a buckled honeycomb form, in contrast with the flat graphene monolayer. Here, we report epitaxial growth of atomically thin flat honeycomb monolayer of group-V element antimony on a Ag(111) substrate. Combined study of experiments and theoretical calculations verify the formation of a uniform and single-crystalline antimonene monolayer without atomic wrinkles, as a new honeycomb analogue of graphene monolayer. Directional bonding between adjacent Sb atoms and weak antimonene-substrate interaction are confirmed. The realization and investigation of flat antimonene honeycombs extends the scope of two-dimensional atomically-thick structures and provides a promising way to tune topological properties for future technological applications. [ABSTRACT FROM AUTHOR]

In this paper, the investigation on the vapor liquid phase equilibrium (VLE) of the ternary system isobutane + trans-1,3,3,3-tetrafluoropropene + trifluoroiodomethane was carried out. The measurements were performed using an apparatus based on the recirculation method at temperatures ranging from 243.150 to 283.150 K. Three models, namely PR-vdW, PR-BM, and PR-MHV2-NRTL, were employed to describe the VLE properties of the system concerned. PR-MHV2-NRTL was the best model, which gave the maximum average absolute pressure relative deviation of 0.85% and the average absolute vapor phase fraction deviation of 0.011. With the regressed binary parameters from ternary VLE data, the binary VLE were well-predicted. A maximum-point ternary azeotropic behavior was exhibited. [ABSTRACT FROM AUTHOR]

An efficient oxidative aminooxyarylation of alkenes under a transition-metal-free condition was described. Under the reaction conditions, N-hydroxyphthalimide (NHPI) reacted readily with N-arylacrylamides to produce cyclic products via a radical C-H functionalization process, achieving both C-O and C-C bonds formation in one pot. This reaction provided a facile access to the valuable aminooxylated oxindoles. The benzylic and a-methylene C(sp³)-H bonds were also aminooxylated under the reaction conditions. [ABSTRACT FROM AUTHOR]

The first highly enantioselective hydrogenation of carbocyclic aromatic amines has been successfully realized using in situ-generated chiral ruthenium complex as catalyst, affording facile access to chiral exocyclic amines with up to 98% ee. [ABSTRACT FROM AUTHOR]

Structural complexity is of fundamental interest in materials science because it often results in unique physical properties and functions. Founded on this idea, the field of solid state chemistry has a long history and continues to be highly active, with new compounds discovered daily. By contrast, the area of two-dimensional (2D) materials is young, but its expansion, although rapid, is limited by a severe lack of structural diversity and complexity. Here, we report a novel 2D semiconductor with a hierarchical structure composed of covalently linked Re6Se8 clusters. The material, a 2D structural analogue of the Chevrel phase, is prepared via mechanical exfoliation of the van der Waals solid Re6Se8Cl2. Using scanning tunneling spectroscopy, photoluminescence and ultraviolet photoelectron spectroscopy, and first-principles calculations, we determine the electronic bandgap (1.58 eV), optical bandgap (indirect, 1.48 eV), and exciton binding energy (100 meV) of the material. The latter is consistent with the partially 2D nature of the exciton. Re6Se8Cl2 is the first member of a new family of 2D semiconductors whose structure is built from superatomic building blocks instead of simply atoms; such structures will expand the conceptual design space for 2D materials research. [ABSTRACT FROM AUTHOR]

Chemistry at the cathode/electrolyte interface plays an important role for lithium -- sulfur batteries in which stable cycling of the sulfur cathode requires confinement of the lithium polysulfide intermediates and their fast electrochemical conversion on the electrode surface. While many materials have been found to be effective for confining polysulfides, the underlying chemical interactions remain poorly understood. We report a new and general lithium polysulfide-binding mechanism enabled by surface oxidation layers of transition-metal phosphide and chalcogenide materials. We for the first time find that CoP nanoparticles strongly adsorb polysulfides because their natural oxidation (forming Co -- O -- P-like species) activates the surface Co sites for binding polysulfides via strong Co -- S bonding. With a surface oxidation layer capable of confining polysulfides and an inner core suitable for conducting electrons, the CoP nanoparticles are thus a desirable candidate for stabilizing and improving the performance of sulfur cathodes in lithium -- sulfur batteries. We demonstrate that sulfur electrodes that hold a high mass loading of 7 mg cm--2 and a high areal capacity of 5.6 mAh cm--2 can be stably cycled for 200 cycles. We further reveal that this new surface oxidation-induced polysulfide-binding scheme applies to a series of transition-metal phosphide and chalcogenide materials and can explain their stabilizing effects for lithium -- sulfur batteries. [ABSTRACT FROM AUTHOR]

We describe the precision synthesis and self-assembly of a series of Janus star polymers with mixed [3:5] heteroarms of polystyrene (PS) and polydimethylsiloxane (PDMS) precisely arranged on a cubic scaffold of T8 polyhedral oligomeric silsesquioxane (POSS) in a spatially segregated fashion. The synthesis begins with a Janus POSS compound with three 2-hydroxylethyl groups on one face and five vinyl pendant groups on the rest vertexes. Facilitated by esterification and a "click" adaptor, two types of polymer arms are attached efficiently by sequential "click" reactions, which constitutes a general approach for modular synthesis of such Janus star polymers. The Janus feature is thoroughly characterized using NMR, FT-IR, SEC, and MALDI-TOF mass spectrometry, and the self-assembled structures are studied by small-angle X-ray scattering (SAXS) experiments. With increasing molecular weight of PS arm, the self-assembled phase transits from lamellae (LAM) to hexagonally packed cylinder (HEX) and further to inversed HEX structure, even though the molecular weight of each PDMS arm is as small as 1.4 kDa. Correspondingly, the feature sizes of these samples are very small. For example, the intercolumnar distance is only ~6.4 nm in the HEX phase, and the column radius is as small as 1.8 nm. It is anticipated that diverse nanostructures can be created from the self-assembly of these Janus star polymers. [ABSTRACT FROM AUTHOR]

An effective pyridine based U-shaped template has been developed to enable a diverse range of meta-C-H functionalizations of phenylacetic acid scaffolds. This new template has extended the reaction scope to cross-coupling with ArBF3K as well as iodination using 1,3-diiodo-5,5-dimethylhydantoin as the iodination reagent. [ABSTRACT FROM AUTHOR]

The recently developed and commercially available carbonyl-reactive tandem mass tags (aminoxyTMT) enable multiplexed quantification of glycans through comparison of reporter ion intensities. However, challenges still exist for collision activated dissociation (CAD) MS/MS based quantification of aminoxyTMT due to the relatively low reporter ion yield especially for glycans with labile structures. To circumvent this limitation, we utilized the unique structural features of N-glycan molecules, the common core sugar sequence (HexNAc)2(Man)3, and common m/z of Yn ions generated from different types of precursors by MS/MS and designed a Y1 ion triggered, targeted MultiNotch MS[sup 3] relative quantification approach based on aminoxyTMT labeling. This approach was implemented on a nanoHILIC-Tribrid quadrupole-ion trap-Orbitrap platform, which enables prescreening of aminoxyTMT labeled N-glycan precursor ions by Y1ion fragment ion mass in a higher-energy collisional dissociation (HCD) MS/MS scan and coisolation and cofragmentation of multiple Yn fragment ions that carry the isobaric tags from the inclusion list in the MS/MS/ MS scan. Through systematical optimization and evaluation using N-glycans released from several glycoprotein standards and human serum proteins, we demonstrated that the Y1 ion triggered, targeted MultiNotch MS3 approach offers improved accuracy, precision, and sensitivity for relative quantification compared to traditional data-dependent MS2and Y1 ion MS3 quantification methods. [ABSTRACT FROM AUTHOR]

Self-assembled organic-inorganic hybrids are a class of promising nanomaterials possessing interesting physiochemical and biological characteristics, making them highly attractive in cancer-related biomedical applications. By using self-assembly as a synthetic tool and various organic/inorganic species as the building blocks, scientists are able to create a myriad of hybrid nanosystems. These promising nanosystems show favorable nano-bio interfacial properties, while still retaining their physical/chemical functionalities. The present Review aims to provide a systematical overview of the self-assembled hybrid nanostructures and highlight their implementations in cancer diagnosis and treatment by highlighting notable recent examples. In addition, the existing challenges in the bench-to-bedside translation of these nanotherapeutics as well as the potential technological breakthroughs in the future studies were also discussed in detail. Overall, this Review presents how clinical oncology could benefit from the convergence of self-assembly paradigm and nanotechnology. [ABSTRACT FROM AUTHOR]

Previous transportation fuel life cycle assessment studies have not fully accounted for the full variability in the crude oil transport stage, for example, transporting a light crude through a high-diameter pipeline, vs transporting a heavy crude through a small-diameter pipeline. We develop a first-principles, fluid mechanics-based crude oil pipeline transportation emissions model (COPTEM) that calculates the greenhouse gas (GHG) emissions associated with pipeline transport as a function of crude oil parameters, pipeline dimensions, and external factors. Additionally, we estimate the emissions associated with the full life cycle of pipeline construction, maintenance, and disposal. This model is applied to an inventory of 62 major Canadian and U.S. pipelines (capacity greater than 100 000 barrels/day) to estimate the variability of GHG emissions associated with pipeline transportation. We demonstrate that pipeline GHG emissions intensities range from 0.23 to 20.3 g CO2e/(bbl·km), exhibiting considerably greater variability than data reported in other studies. A sensitivity analysis demonstrates that the linear velocity of crude transport and pipeline diameter are the most impactful parameters driving this variability. To illustrate one example of how COPTEM can be used, we develop an energy efficiency gap analysis to investigate the possibilities for more efficient pipeline transport of crude oil. [ABSTRACT FROM AUTHOR]

Dislocations in crystals affect material properties and are essential for crystal growth near equilibrium, yet their genesis in the absence of external or internal stresses is unresolved. X-ray topography has revealed microscopic inclusions as dislocation sources, but the real-time creation of a dislocation by a particulate inclusion has not been reported. In situ atomic force microscopy (AFM) was used herein to visualize dislocation generation in an L-cystine crystal by a cube-like hematite particle embedded in, and slightly inclined with respect to, the L-cystine {0001} surface. The particle produced two pairs of heterochiral screw dislocations with opposing Burgers vectors. After overgrowth of the particle, dissolution in undersaturated solutions revealed the dislocations once again until the detachment of the particle exposed a flat basal plane devoid of dislocations, thereby corroborating the essential role of the particle. Hematite particles with their flat faces parallel or at high angle to the surface, as well as spherical poly(styrene) particles, did not produce dislocations, suggesting that shape and orientation of the particle with respect to the step train advancing across the growing crystal surface are critical features for dislocation generation. [ABSTRACT FROM AUTHOR]

Graphene-or graphene oxide (GO)-supported metallic nanoparticles and single metal atom as potentially effective catalysts for chemical reactions have recently received extensive research interests. However, metal utilization in nanoparticle catalysts is limited and metal atoms readily drift on the graphene surface and consequently form aggregated large particles, making practical applications limited. Here, we report metal ions directly immobilized on GO as a novel GO-supported single-ion catalyst for chemiluminecence (CL) reactions. It is found that GO-supported cobalt ions with good stability could catalyze strongly luminol -- H2O2 and lucigenin -- H2O2 CL reactions, accompanied by dramatically enhanced CL emission. Theoretical studies reveal that the coupling between Co2+ and GO induces effective polarization charges, improving chemical activity of the reaction site, which promotes the generation of intermediate radicals and accelerates the CL reactions. This work may be generalized to other GOsupported metal ions as catalysts for a wide range of chemical reactions. The developed GO-supported cobalt single-ion nanocomposites as nanointerfaces may find future applications in CL bioassays. [ABSTRACT FROM AUTHOR]

Rapid detection of highly contagious pathogens is the key to increasing the probability of survival and reducing infection rates. We developed a sensitive and quantitative lateral flow assay for detection of Ebola virus (EBOV) glycoprotein with a novel multifunctional nanosphere (RNs@Au) as a reporter. Each RNs@Au contains hundreds of quantum dots and dozens of Au nanoparticles and can achieve enhanced dualsignal readout (fluorescence signal for quantitative detection and colorimetric signal for visual detection). Antibody (Ab) and streptavidin (SA) were simultaneously modified onto the RNs@ Au to label the target and act as signal enhancer. After the target was labeled by the Ab--RNs@Au--SA and captured on the test line, biotin-modified RNs@Au was used to amplify the dual signal by the reaction of SA with biotin. The assay enables naked-eye detection of 2 ng/mL glycoprotein within 20 min, and the quantitative detection limit is 0.18 ng/mL. Additionally, the assay has been successfully tested in field work for detecting EBOV in spiked urine, plasma, and tap water samples and is thus a promising candidate for early diagnosis of suspect infections in EBOV-stricken areas. [ABSTRACT FROM AUTHOR]

The carbon-carbon bond formation via autoxidation of organoboronic acid using 1 atm of O2 is achieved in a simple, clean, and green fashion. The approach allows a technically facile and environmentally benign access to structurally diverse heteroaromatics with medicinally privileged scaffolds. The strategy also displays its practicality and sustainability in the resynthesis of marketed drugs Crestor and pyrimethamine. [ABSTRACT FROM AUTHOR]

Buckminsterfullerene (C60), known for its strong radical scavenging properties, has been studied extensively for its biomedical applications. Its clinical use would be promoted by novel functionalization of C60 with the aid of drug delivery carriers based on nanoparticle technologies. Cellulose nanocrystals (CNCs) have recently been exploited as a promising nanoplatform for drug delivery, owing to their intriguing attributes such as nanoscale dimensions, low toxicity, broad chemical-modifying capacity, and biocompatibility. Herein, cellulose nanocrystals carrying buckminsterfullerene (CNC-C60) have been synthesized via amine functionalization of CNCs and subsequent grafting of C60 onto the surface of amine-terminated CNCs. FTIR and XPS measurements confirmed the success of the synthesis, which was further evidently supported by TGA analysis. Given atomic compositions of samples by elemental analysis, we figured out a C60 content of 0.17 mmol/g of CNC-C60, equivalent to 34 C60 molecules/1000 anhydroglucose units (AGU). Afterward, CNC-C60 was evaluated for its antiradical effects on scavenging hydroxyl radicals in vitro. The ease of synthesis and significant radical scavenging activity make CNC-C60 a promising novel antioxidant agent for biomedical use. [ABSTRACT FROM AUTHOR]

Three types of lanthanide coordination polymers based on mixed methylmalonic acid (H2MMA) and isonicotinic acid (HINA), two-dimensional (2D) [Ln2(MMA)2(INA)2(H2O)3]n (Ln = Eu (1); Gd (2)) and [Ln(MMA)(INA)(H2O)2]n (Ln = Gd (3); Tb (4)) as well as one-dimensional (1D) [Dy(MMA)(INA)(H2O)2]n (5), have been hydrothermally synthesized, which can be controlled by the usage amount of H2MMA or the type of Ln3+ ion. Complexes 1 and 2 contain two kinds of 1D lanthanide chain units (wave and linear), which are alternately linked by the MMA2-- and INA-ligands to form a 2D layer structure. Complexes 3 and 4 also have a 2D layer structure, consisting of 1D linear lanthanide chain units, MMA2-- and INA-linkers. Compound 5 shows a 1D linear chain structure, in which the neighboring Dy3+ ions are fastened by the carboxylate groups from MMA2-- and INA-ligands. The magnetic studies reveal the presence of ferromagnetic Gd…Gd coupling in the 1D chain units of 2 and 3, which display significant cryogenic magnetocaloric effects with a maximum -▵Sm value of 34.32 J kg-1 K-1 at 3 K and 36.02 J kg-1 K-1 at 2 K for ▵H = 7 T, respectively. Furthermore, the solid-state photophysical properties of 1 and 4 exhibit strong characteristic Eu3+ and Tb3+ photoluminescent emission in the visible region, indicating that Eu- and Tb-based luminescences are sensitized effectively by the energy transfer from the INA-ligand to the metal centers. [ABSTRACT FROM AUTHOR]

We present a comprehensive computational study of interaction of a SO2 with water molecules in the gas phase and with the surface of various sized water nanodroplets to investigate the solvation behavior of SO2 in different atmospheric environments. Born-Oppenheimer molecular dynamics (BOMD) simulation shows that, in the gas phase and at a temperature of 300 K, the dominant interaction between SO2 and H2O is (SO[sub 2])S⋯O(H[sub 2]O), consistent with previous density-functional theory (DFT) computation at 0 K. However, at the surface of a water nanodroplet, BOMD simulation shows that the hydrogen-bonding interaction of (SO[sub 2])O⋯H(H[sub 2]O) becomes increasingly important with the increase of droplet size, reflecting a marked effect of the water surface on the SO2 solvation. This conclusion is in good accordance with spectroscopy evidence btained previously (J. Am. Chem. Soc. 2005, 127, 16806; J. Am. Chem. Soc. 2006, 128, 3256). The prevailing interaction (SO[sub 2])O⋯H(H[sub 2]O) on a large droplet is mainly due to favorable exposure of H atoms of H2O at the air-water interface. Indeed, the conversion of the dominant interaction in the gas phase (SO[sub 2])S⋯O(H[sub 2]O) to the dominant interaction on the water nanodroplet (SO[sub 2])S⋯O(H[sub 2]O) may incur effects on the SO2 chemistry in atmospheric aerosols because the solvation of SO2 at the water surface can affect the reactive sites and electrophilicity of SO2. Hence, the solvation of SO2 on the aerosol surface may have new implications when studying SO2 chemistry in the aerosol-containing troposphere. [ABSTRACT FROM AUTHOR]

Lead (Pb) pollution emission from China is becoming a potential worldwide threat. Pb isotopic composition analysis is a useful tool to accurately trace the Pb sources of aerosols in atmosphere. In this study, a comprehensive data set of Pb isotopes for coals, Pb/Zn ores, and fuels from China was presented. The ratios of 206Pb/207Pb and 208Pb/206Pb in the coals were in the range of 1.114-1.383 and 1.791-2.317, similar to those from Europe, Oceania, and South Asia, but different from those from America (p < 0.01). The Pb/Zn ores had 206Pb/207Pb and 208Pb/206Pb in 1.020-1.183 and 2.088-2.309, less radiogenic than the coals. Leaded gasolines showed similar Pb isotopic compositions to Pb/Zn ores, with unleaded gasolines and diesels being mixed sources. The average Pb isotopic ratios of gasolines and diesels were significantly different (p < 0.01) from those of coals in China, leading to the possibility to discriminate Pb in fuels from in coals. Urban aerosols demonstrated similar Pb isotopic compositions to coals, Pb/Zn ores, and fuels in China. After removing the leaded gasoline, the Pb in aerosols is more radiogenic, supporting the heavy contribution of coal combustion to the atmospheric Pb pollution. [ABSTRACT FROM AUTHOR]

It is a considerable challenge to realize 3D fluorescence quantification of macrodispersion of day fillers in a polymer matrix mainly owing to quenching of light emission in the solid state. Herein, a strong light emission is generated within the interlaminated day as a result of a cation—π interaction between cationic surfactant and fluorescent polycyclic aromatic hydrocarbon when they are cointercalated into clay. Confocal laser scanning microscopy (CLSM) is applied for 3D imaging of macrodispersion of the fluorescence-labeled clay fillers in a silicone rubber matrix. More importantly, the quantification of macrodispersion of day fillers in the overall polymer composite is established by a statistical model. The proposed method fills in an important gap in the standard for macrodispersion quantification of inorganic fillers in polymer composites. [ABSTRACT FROM AUTHOR]

Cross-coupling of (hetero)arylthiols with arylzinc reagents via C-S cleavage was performed under transition-metal-free conditions. The reaction displays a wide scope of substrates and high functional-group tolerance. Electron-rich and -deficient (hetero)arylthiols and arylzinc reagents can be employed in this transformation. Mg2+ and Li+ ions were demonstrated to facilitate the reaction. [ABSTRACT FROM AUTHOR]

Dendrimer-based nanoplatforms have exhibited wide prospects in the field of nanomedicine for drug delivery, without great success due to many predicaments of cytotoxicity, high cost, and low yield. In this work, we report a feasible strategy on dynamic cross-linkings of low-generation peptide dendrimers into bioreducible nanogels for efficient drug controlled release. With a facile fabrication, the disulfide cross-linking of biocompatible peptide dendrimers successfully possess well-defined and stable nanostructures with abundant expanded voids for efficient molecular encapsulation. More importantly, high reducing condition is capable of triggering the cleavage of disulfide bonds, the disintegration of peptide-dendrimeric nanogels, and stimuli-responsive release of guest molecules. The bioreducible nanogels improve antitumor drug internalization, contribute to endosomal escape, and realize intracellular drug controlled release. The doxorubicin-loaded nanogels afford high antitumor efficiency and reduce the side effects to BALB/c mice bearing 4T1 tumor. Therefore, dynamic cross-linkings of low-generation dendrimers into smart nanogels will be an alternative and promising strategy to resolve the dilemmas of current dendrimer-based nanocarriers as well as develop innovative nanoplatforms. [ABSTRACT FROM AUTHOR]

Structurally controlled nanoparticles, such as core-shell nanocomposite particles by combining two or more compositions, possess enhanced or new functionalities that benefited from the synergistic coupling of the two components. Here we report new nanocomposite particles with self-assembled porphyrin arrays as the core surrounded by amorphous silica as the shell. The synthesis of such nanocomposite nanoparticles was conducted through a combined surfactant micelle confined self-assembly and silicate sol-gel process using optically active porphyrin as a functional building block. Depending on kinetic conditions, these particles exhibit structure and function at multiple length scales and locations. At the molecular scale, the porphyrins as the building blocks provide well-defined macromolecular structures for noncovalent self-assembly and unique chemistry for high-yield generation of singlet oxygen for photodynamic therapy (PDT). On the nanoscale, controlled noncovalent interactions of the porphyrin building block result in an extensive self-assembled porphyrin network that enables efficient energy transfer and impressive fluorescence for cell labeling, evidenced by absorption and photoluminescence spectra. Finally, the thin silicate shell on the nanoparticle surface allows easy functionalization, and the resultant targeting porphyrin-silica nanocomposites can selectively destroy tumor cells upon receiving light irradiation. [ABSTRACT FROM AUTHOR]

Recently, all-inorganic cesium lead halide (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) have drawn wide attention because of their excellent optoelectronic properties and potential applications. However, one of the most significant challenges of such NCs is their low stability against protonic solvents. In this work, we demonstrate that by incorporating a highly branched capping ligand, trioctylphosphine oxide (TOPO), into the traditional oleic acid/oleylamine system, monodisperse CsPbX3 NCs with excellent optoelectronic properties can be achieved at elevated temperatures (up to 260 °C). The size of such NCs can be varied in a relatively wide range. The capping of TOPO on NCs has been verified through Fourier transform infrared spectroscopy measurement. More importantly, the presence of TOPO can dramatically improve the stability of CsPbX3 NCs against ethanol treatment. After ethanol treatment for 100 min, the emission intensity of the TOPO-capped sample dropped only 5%, whereas that of non-TOPO-capped NCs dropped up to 86%. This work may shed some light on the preparation and application of CsPbX3 NCs with higher stability. [ABSTRACT FROM AUTHOR]