Nonenzymatic nucleic acid amplification techniques (
e.g.
the hybridization chain reaction, HCR) have shown promising potential for amplified detection of biomarkers. However, the traditional HCR ...occurs through random diffusion of DNA hairpins, making the kinetics and efficiency quite low. By assembling DNA hairpins at the vertexes of tetrahedral DNA nanostructures (TDNs), the reaction kinetics of the HCR is greatly accelerated due to the synergetic contributions of multiple reaction orientations, increased collision probability and enhanced local concentrations. The proposed quadrivalent TDN (qTDN)-mediated hyperbranched HCR has a ∼70-fold faster reaction rate than the traditional HCR. The approximately 76% fluorescence resonance energy transfer (FRET) efficiency obtained is the highest in the reported DNA-based FRET sensing systems as far as we know. Moreover, qTDNs modified by hairpins can easily load drugs, freely traverse plasma membranes and be rapidly cross-linked
via
the target-triggered HCR in live cells. The reduced freedom of movement as a result of the large crosslinked structure might constrain the hyperbranched HCR in a confined environment, thus making it a promising candidate for
in situ
imaging and photodynamic therapy. Hence, we present a paradigm of perfect integration of DNA nanotechnology with nucleic acid amplification, thus paving a promising way to the improved performance of nucleic acid amplification techniques and their wider application.
Nonenzymatic nucleic acid amplification techniques (
e.g.
the hybridization chain reaction, HCR) have shown promising potential for amplified detection of biomarkers.
Heck reaction is one of the most important carbon‐carbon bond forming reactions with wide applications in organic synthesis. Considerable advances of enantioselective Heck reaction have been achieved ...in the past decades. This review focuses on recent development of catalytic asymmetric Heck reaction and reductive Heck reaction, which covers intermolecular and intramolecular versions since 2011. The article is organized in terms of the catalysts and olefin substrates.
Recent progress of catalytic asymmetric Heck reactions and reductive Heck reactions since 2011 is described.
Parkinson’s disease (PD) is characterized by dopaminergic (DA) neuron loss and the formation of cytoplasmic protein inclusions. Although the exact pathogenesis of PD is unknown, iron dyshomeostasis ...has been proposed as a potential contributing factor. Emerging evidence suggests that glial cell activation plays a pivotal role in ferroptosis and subsequent neurodegeneration. We review the association between iron deposition, glial activation, and neuronal death, and discuss whether and how ferroptosis affects α-synuclein aggregation and DA neuron loss. We examine the possible roles of different types of glia in mediating ferroptosis in neurons. Lastly, we review current PD clinical trials targeting iron homeostasis. Although clinical trials are already evaluating ferroptosis modulation in PD, much remains unknown about metal ion metabolism and regulation in PD pathogenesis.
Iron uptake, storage, efflux, and utilization are essential for maintaining iron homeostasis. Abnormal expression of proteins involved in these processes related to iron homeostasis may cause iron overload and induce subsequent ferroptosis, which is associated with the pathogenesis of neurodegenerative disease.Crosstalk between glia and neurons underlies the ferroptotic alterations in DA neurons and form a vicious circle in promoting PD pathogenesis.Possible mechanisms of iron transfer between glia and neurons include exosomes and tunneling nanotubes. They may determine the efficacy of ferroptosis inhibitors and provide a clue for exploring novel therapeutic interventions for PD.Joint medications with ferroptosis inhibitors and anti-inflammatory medicines may provide a potential strategy for the treatment of PD and related neurodegenerative diseases.
Pentafluorosulfanyl chloride (SF5Cl) is the most prevalent reagent for the incorporation of SF5 group into organic compounds. However, the preparation of SF5Cl often relies on hazardous reagents and ...specialized apparatus. Herein, we described a safe and practical synthesis of a bench‐stable and easy‐to‐handle solution of SF5Cl in n‐hexane under gas‐reagent‐free conditions. The synthetic application of SF5Cl was demonstrated through the unprecedented reaction with diazo compounds. The chemoselective hydro‐ and chloropentafluorosulfanylations of α‐diazo carbonyl compounds were developed in the presence of K3PO4 or copper catalyst, respectively. These reactions provide a direct and efficient access to various α‐pentafluorosulfanyl carbonyl compounds of high value for potential applications.
A practical synthesis of SF5Cl from sulfur powder, dry KF, and trichloroisocyanuric acid (TCCA) in MeCN is described. The new synthetic utility of SF5Cl is well demonstrated by the chemoselective hydro(chloro)pentafluorosulfanylation of diazo compounds.
Conspectus Olefin functionalization represents one of the most important synthetic transformations in organic synthesis. Over the past decades, palladium-catalyzed enantioselective Heck reactions, ...and Heck/anion-capture domino sequences through olefin carbopalladation followed by termination of the resulting alkyl-Pd species have been extensively developed. Extension of the coupling partners from classical olefins to other π-components would enable further advances and open new space in this field. Aromatics are important and easily available bulk chemicals. Dearomative transformation of endocyclic aromatic π-bonds via the Heck reaction pathway provides an efficient and straightforward route to structurally diverse alicyclic compounds. Nevertheless, major challenges for this transformation include aromaticity breaking and reactivity and selectivity issues. Recently, we have engaged in developing catalytic enantioselective dearomative Heck reactions and related domino reactions. A range of heteroarenes and naphthalenes have been employed as novel π-coupling partners in these reactions. Through dearomative migratory insertion of endocyclic aromatic C–C π-bonds followed by interception of the transient alkyl-Pd species, enantioselective Heck reactions, reductive Heck reactions, Heck/anion-capture difunctionalization reactions, and heteroarenyne cycloisomerization reactions have been established. Relying on β-H elimination of the alkyl-Pd intermediate, we realized enantioselective dearomative Heck reactions with a range of aromatic partners, including heterocyclic indoles, pyrroles, furans, benzofurans, and more challenging carbocyclic naphthalenes. In order to avoid the utilization of organohalide electrophiles, heteroarenyne cycloisomerization reaction was developed by merging intermolecular alkyne hydropalladation with intramolecular dearomative Heck reaction. Cycloisomerization of alkyne-tethered indoles delivered chiral indolines in excellent enantioselectivities with 100% atom economy. On the other hand, Heck/anion-capture domino sequences were established through nucleophilic trapping of the alkyl-Pd intermediate. When HCO2Na was employed as a capturing reagent, the enantioselective dearomative reductive Heck reaction of indoles was realized. By employing other nucleophiles, including alkynes, N-sulfonylhydrazones, and organoboron reagents, we developed a series of dearomative difunctionalization reactions. Two vicinal stereocenters with excellent enantio- and diastereoselectivities were constructed in the corresponding Heck/Sonogashira, Heck/vinylation, and Heck/borylation reactions. Moreover, dearomative 1,4-diarylation of naphthalenes was developed through Heck/Suzuki domino reactions, in which competitive C–H arylation and the direct Suzuki reaction were almost fully inhibited in the presence of a spiro-phosphoramidite ligand. In this Account, we provide a panoramic view of our results since 2015 on enantioselective Heck reactions and related domino sequences by extending the coupling partners from classical olefins to aromatic systems. Investigations outlined in this Account established straightforward and efficient access to a variety of structurally diverse chiral heteropolycyclic molecules starting from simple and planar aromatic compounds.
We herein report a new coordination network that deforms in a smooth and reversible manner under either thermal or pressure stimulation. Concomitantly, the organic fluorophores coordinatively bound ...to the channel in a face‐to‐face arrangement respond to this structural deformation by finely adapting their conformation and arrangement. As a result, the material exhibits a remarkable dual‐stimuli‐responsive luminescence shift across almost the entire visible region: The emission color of the crystal gradually changes from cyan to green upon heating and then to red upon pressure compression. Furthermore, each stage exhibits a linear dependence of both the emission maximum and intensity on the stimulus and is fully reversible.
Coping with pressure and heat: In response to changes in temperature and pressure, the flexible scaffold of a luminescent coordination network underwent smooth and reversible structural deformation that regulated the conformation and arrangement of the emissive organic molecules coordinatively bound to the channel in the structure. As a result, a reversible fluorescence shift across almost the entire visible region was observed (see picture).
Precise design of low‐cost, efficient and definite electrocatalysts is the key to sustainable renewable energy. Herein, this work develops a targeted‐anchored and subsequent spontaneous‐redox ...strategy to synthesize nickel‐iron layered double hydroxide (LDH) nanosheets anchored with monodispersed platinum (Pt) sites (Pt@LDH). Intermediate metal‐organic frameworks (MOF)/LDH heterostructure not only provides numerous confine points to guarantee the stability of Pt sites, but also excites the spontaneous reduction for PtII. Electronic structure, charge transfer ability and reaction kinetics of Pt@LDH can be effectively facilitated by the monodispersed Pt moieties. As a result, the optimized Pt@LDH that with the 5% ultra‐low content Pt exhibits the significant increment in electrochemical water splitting performance in alkaline media, which only afford low overpotentials of 58 mV at 10 mA cm−2 for hydrogen evolution reaction (HER) and 239 mV at 10 mA cm−2 for oxygen evolution reaction (OER), respectively. In a real device, Pt@LDH can drive an overall water‐splitting at low cell voltage of 1.49 V at 10 mA cm−2, which can be superior to most reported similar LDH‐based catalysts. Moreover, the versatility of the method is extended to other MOF precursors and noble metals for the design of ultrathin LDH supported monodispersed noble metal electrocatalysts promoting research interest in material design.
A targeted‐anchored and subsequent spontaneous‐redox strategy is developed to synthesize nickel‐iron layered double hydroxide (LDH) nanosheets anchored with monodispersed platinum (Pt) sites (Pt@LDH). As‐prepared Pt@LDH‐4h can drive an overall water‐splitting at low cell voltage of 1.49 V at 10 mA cm−2, which can be superior to most reported similar LDH‐based catalysts.
Recently developed CsPbX3 (X = Cl, Br, and I) perovskite quantum dots (QDs) hold great potential for various applications owing to their superior optical properties, such as tunable emissions, high ...quantum efficiency, and narrow linewidths. However, poor stability under ambient conditions and spontaneous ion exchange among QDs hinder their application, for example, as phosphors in white‐light‐emitting diodes (WLEDs). Here, a facile two‐step synthesis procedure is reported for luminescent and color‐tunable CsPbX3–zeolite‐Y composite phosphors, where perovskite QDs are encapsulated in the porous zeolite matrix. First zeolite‐Y is infused with Cs+ ions by ion exchange from an aqueous solution and then forms CsPbX3 QDs by diffusion and reaction with an organic solution of PbX2. The zeolite encapsulation reduces degradation and improves the stability of the QDs under strong illumination. A WLED is fabricated using the resulting microscale composites, with Commission Internationale de I'Eclairage (CIE) color coordinates (0.38, 0.37) and achieving 114% of National Television Standards Committee (NTSC) and 85% of the ITU‐R Recommendation BT.2020 (Rec.2020) coverage.
A synthesis procedure for luminescent perovskite quantum dots embedded in zeolite‐Y crystals is presented. The structural and optical properties of the resulting composites are characterized in detail. Zeolite embedding improves the stability of perovskite quantum dots to degradation. Finally, the composites are used to produce a white‐light‐emitting diode with wide color gamut.
Reprogrammed metabolism is a hallmark of cancer. However, the metabolic dependency of cancer, from tumour initiation through disease progression and therapy resistance, requires a spectrum of ...distinct reprogrammed cellular metabolic pathways. These pathways include aerobic glycolysis, oxidative phosphorylation, reactive oxygen species generation, de novo lipid synthesis, fatty acid β-oxidation, amino acid (notably glutamine) metabolism and mitochondrial metabolism. This Review highlights the central roles of signal transducer and activator of transcription (STAT) proteins, notably STAT3, STAT5, STAT6 and STAT1, in orchestrating the highly dynamic metabolism not only of cancer cells but also of immune cells and adipocytes in the tumour microenvironment. STAT proteins are able to shape distinct metabolic processes that regulate tumour progression and therapy resistance by transducing signals from metabolites, cytokines, growth factors and their receptors; defining genetic programmes that regulate a wide range of molecules involved in orchestration of metabolism in cancer and immune cells; and regulating mitochondrial activity at multiple levels, including energy metabolism and lipid-mediated mitochondrial integrity. Given the central role of STAT proteins in regulation of metabolic states, they are potential therapeutic targets for altering metabolic reprogramming in cancer.
The Kepler mission has discovered thousands of exoplanets around various stars with different spectral types (M, K, G, and F) and thus different masses and effective temperatures. Previous studies ...have shown that the planet occurrence rate, in terms of the average number of planets per star, drops with increasing stellar effective temperature (Teff). In this paper, with the final Kepler Data Release (DR25) catalog, we revisit the relation between stellar effective temperature (as well as mass) and planet occurrence, but in terms of the fraction of stars with planets and the number of planets per planetary system (i.e., planet multiplicity). We find that both the fraction of stars with planets and planet multiplicity decrease with increasing stellar temperature and mass. Specifically, about 75% late-type stars (Teff < 5000 K) have Kepler-like planets with an average planet multiplicity of ∼2.8, while for early-type stars (Teff > 6500 K) this fraction and the average multiplicity fall down to ∼35% and ∼1.8, respectively. The decreasing trend in the fraction of stars with planets is very significant with ΔAIC > 30, though the trend in planet multiplicity is somewhat tentative with ΔAIC ∼ 5. Our results also allow us to derive the dispersion of planetary orbital inclinations in relationship with stellar effective temperature. Interestingly, it is found to be similar to the well-known trend between obliquity and stellar temperature, indicating that the two trends might have a common origin.
PDF
