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Cr-(VI) is a kind of heavy metal ion with strong toxicity to the environment. A better treatment strategy is to reduce Cr-(VI) to low toxic Cr-(III). However, how to implement this process cleanly and efficiently is still a challenge. In this study, ZnS/ZnSe/MoSe2 (ZZM) nanocomposites with dual type-II heterojunctions are synthesized by solvothermal and ion exchange methods for the first time. The photocatalytic performance of ZZM nanocomposites is evaluated by the photocatalytic reduction of Cr-(VI) under visible light irradiation. The ZZM-1:1 nanocomposites can reduce 96.0% of Cr-(VI), and the reaction rate constant is 2.476 × 10–2 min–1, which is 3.67, 3.44, and 10.49 times higher than those of MoSe2, ZnSe, and ZnS, respectively. The improved photocatalytic activity can be assigned to the dual heterostructures, which effectively promotes the separation and transmission of photogenerated charge carriers. Meanwhile, the extended light response range and the increased specific surface area also contribute to the improvement of the photocatalytic efficiency. After five cycles, the ZZM-1:1 nanomaterial still shows an 81.1% photoreduction efficiency for Cr-(VI). The experimental results show that the ZZM nanocomposites have great potential in removing Cr-(VI) from wastewater. [ABSTRACT FROM AUTHOR]

Wereport a simple, yet general, approach to monodisperse MPt (M = Fe,Co, Ni, Cu, Zn) nanoparticles (NPs) by coreduction of M(acac)2and Pt(acac)2(acac = acetylacetonate) with oleylamineat 300 °C. In the current reaction condition, oleylamine servesas the reducing agent, surfactant, and solvent. As an example, wedescribe in details the synthesis of 9.5 nm CoPt NPs with their compositionscontrolled from Co37Pt63to Co69Pt31. These NPs show composition-dependent structural and magneticproperties. The unique oleylamine reduction process makes it possibleto prepare MPt NPs with their physical properties and surface chemistrybetter rationalized for magnetic or catalytic applications. [ABSTRACT FROM AUTHOR]

DNA-templated reactions have found wide applications in sensing and drug discovery. However, this strategy has been limited to the use of nucleic acids as templating elements to direct the proximity effect. Herein, we describe a versatile p rotein- t emplated sp lit a ptamer c lick l igation r eaction (PT-SpA-CLR) in which the protein template-induced covalent proximity ligation of split aptamer elements enables translating protein/aptamer binding events into the output of ligated DNA products. A ligation yield of >80% is observed for three model protein templates, including VEGF 165 , PDGF-BB, and SARS-CoV-2 S1. The ligation reaction compensates for the weakness of reduced binding affinity resulting from splitting the aptamer, as evidenced by an approximately 2-fold lower dissociation constant than the non-ligated system. This newly developed PT-SpA-CLR strategy is further integrated with colorimetric or fluorescent reporting mechanisms to achieve easy-to-use and low-cost biosensors utilizing ligation to produce a fully active G-quadruplex or an RNA-cleaving DNAzyme to report protein binding. Both assays can achieve specific detection of an intended protein target with a limit of detection at the picomolar level even when challenged in biological samples. The combined PT-SpA-CLR and versatile sensing strategies offer attractive universal platforms for efficient detection of protein biomarkers.

Nucleic acids play a pivotal role in the diagnosis of diseases. However, rapid, cost-efficient, and ultrasensitive identification of nucleic acid targets still represents a significant challenge. Herein, we describe an enzyme-free DNA amplification method capable of achieving accurate and ultrasensitive nucleic acid detection via D NA- t emplated c lick l igation c hain r eaction (DT-CLCR) catalyzed by a h eterogeneous n anocatalyst made of Cu 2 O (hnCu 2 O). This hnCu 2 O-DT-CLCR method is built on two cross-amplifying hnCu 2 O-catalyzed DNA-templated azide-alkyne cycloaddition-driven DNA ligation reactions that boast a fast reaction rate and a high DNA ligation yield in minutes, enabling rapid exponential amplification of specific DNA targets. This newly developed hnCu 2 O-DT-CLCR-enabled DNA amplification strategy is further integrated with two signal reporting mechanisms to achieve low-cost and easy-to-use biosensors: an electrochemical sensor through the conjugation of a methylene blue redox reporter to a DNA probe used in hnCu 2 O-DT-CLCR and a colorimetric sensor through the incorporation of the split-to-intact G-quadruplex DNAzyme encoded into hnCu 2 O-DT-CLCR. Both sensors are able to achieve specific detection of the intended DNA target with a limit of detection at aM ranges, even when challenged in complex biological matrices. The combined hnCu 2 O-DT-CLCR and sensing strategies offer attractive universal platforms for enzyme-free and yet efficient detection of specific nucleic acid targets.

L1 0 -FePt nanoparticles (NPs) have great potential in areas of advanced magnetic and catalytic applications. Here, we present a facile control route for synthesis of hard magnetic L1 0 -FePt NPs in which halide ions (Cl - , Br - , or I - ) were added to the synthetic process to promote the phase transformation. It is confirmed that the strong ionic binding force between halide ions and Fe 3+ or Pt 2+ ions could facilitate the formation of L1 0 -FePt phase due to favoring growth of FePt NPs in a more thermodynamically stable way, which enables the formation of an ordered structure. L1 0 -FePt NPs with the highest coercivity of 8.64 kOe and saturation magnetization of 64.21 emu/g at room temperature can be directly obtained by controlling the amount of the halide ions. In comparison with conventional solution phase reduction methods, the halide ion-assisted method shows enhanced capability to tune the growth of hard magnetic bimetallic NPs, particularly Pt-based bimetallic NPs.

Targeted covalent inhibitors of protein-protein interactions differ from reversible inhibitors in that the former bind and covalently bond the target protein at a specific site of the target. The site specificity is the result of the proximity of two reactive groups at the bound state, for example, one mild electrophile in the inhibitor and a natural cysteine in the target close to the ligand binding site. Only a few pharmaceutically relevant proteins have this structural feature. Grb2, a key adaptor protein in maintaining the ERK activity via binding Sos1 to activated RTKs, is one: the N-terminal SH3 domain of Grb2 (Grb2 N-SH3 ) carries a unique solvent-accessible cysteine Cys 32 close to its Sos1-binding site. Here we report the design of a peptide-based antagonist (a reactive peptide) that specifically binds to Grb2 N-SH3 and subsequently undergoes a nucleophilic reaction with Cys 32 to form a covalent bond thioether, to block Grb2-Sos1 interaction. Through rounds of optimization, we eventually obtained a dimeric reaction reactive peptide that can form a covalent adduct with endogenous Grb2 protein inside the cytosol of SK-BR-3 human breast cancer cells with pronounced inhibitory effect on cell mobility and viability. This work showcases a rational design of Grb2-targeted site-specific covalent inhibitor and its pronounced anticancer effect by targeting Grb2-Sos1 interaction.

Intracellular reactions on nonenzymatic proteins that activate cellular signals are rarely found. We report one example here that a designed peptide derivative undergoes a nucleophilic reaction specifically with a cytosolic PDZ protein inside cells. This reaction led to the activation of ephrin-B reverse signaling, which subsequently inhibited SDF-1 induced neuronal chemotaxis of human neuroblastoma cells and mouse cerebellar granule neurons. Our work provides direct evidence that PDZ-RGS3 bridges ephrin-B reverse signaling and SDF-1 induced G protein signaling for the first time.

We report a general approach to NiAu alloy nanoparticles (NPs) by co-reduction of Ni(acac)2 (acac = acetylacetonate) and HAuCl4·3H2O at 220 °C in the presence of oleylamine and oleic acid. Subject to potential cycling between 0.6 and 1.0 V (vs reversible hydrogen electrode) in 0.5 M H2SO4, the NiAu NPs are transformed into core/shell NiAu/Au NPs that show much enhanced catalysis for hydrogen evolution reaction (HER) with Pt-like activity and much robust durability. The first-principles calculations suggest that the high activity arises from the formation of Au sites with low coordination numbers around the shell. Our synthesis is not limited to NiAu but can be extended to FeAu and CoAu as well, providing a general approach to MAu/Au NPs as a class of new catalyst superior to Pt for water splitting and hydrogen generation.

We present simple, self-assembled, and robust fabrication of ultrahigh density cobalt nanowire arrays. The binary Co-Al and Co-Si systems phase-separate during physical vapor deposition, resulting in Co nanowire arrays with average diameter as small as 4.9 nm and nanowire density on the order of 10(16)/m(2). The nanowire diameters were controlled by moderating the surface diffusivity, which affected the lateral diffusion lengths. High resolution transmission electron microscopy reveals that the Co nanowires formed in the face-centered cubic structure. Elemental mapping showed that in both systems the nanowires consisted of Co with undetectable Al or Si and that the matrix consisted of Al with no distinguishable Co in the Co-Al system and a mixture of Si and Co in the Co-Si system. Magnetic measurements clearly indicate anisotropic behavior consistent with shape anisotropy. The dynamics of nanowire growth, simulated using an Ising model, is consistent with the experimental phase and geometry of the nanowires.

To label proteins covalently, one faces a trade-off between labeling a protein specifically and using a small tag. Often one must compromise one parameter for the other or use additional components, such as an enzyme, to satisfy both requirements. Here, we report a new reaction that covalently labels proteins by using engineered coiled-coil peptides. Harnessing the concept of "proximity-induced reactivity", the 21-amino-acid three-heptad peptides CCE/CCK were modified with a nucleophilic cysteine and an α-chloroacetyl group at selected positions. When pairs of coiled coils associated, an irreversible covalent bond spontaneously formed between the peptides. The specificity of the cross-linking reaction was characterized, the probes were improved by making them bivalent, and the system was used to label a protein in vitro and receptors on the surface of mammalian cells.

We report a one-pot synthesis of urchin-like FePd-Fe3O4 nanocomposites, spherical clusters of FePd nanoparticles (NPs) with spikes of Fe3O4 nanorods (NRs), via controlled thermal decomposition of Fe(CO)5 and reduction of Pd(acac)2. The FePd NPs with sizes between 6 and 9 nm self-aggregate into 60 nm superparticles (SPs), and Fe3O4 NRs grow on the surface of these SPs. Reductive annealing at 500 °C converts the FePd-Fe3O4 into exchange-coupled nanocomposites L1(0)-FePd-Fe with their Hc tunable from 0.8 to 2.6 kOe and Ms controlled from 90 to 190 emu/g. The work provides a general approach to L1(0)-FePd-Fe nanocomposite magnets for understanding exchange coupling at the nanoscale. The concept may be extended to other magnetic nanocomposite systems and may help to build superstrong magnets for magnetic applications.