Fluorescent Probes for Cysteine and Cysteine Oxidation Imaging

Cysteine is an important regulator of redox processes.Due to the nucleophilic and oxidative sensitivity,cysteine residues in proteins can be oxidized by intracellular reactive oxygen species(ROS),which can lead to protein structural and functional changes.Hence,the development of fluorescent probes to image cysteine and cysteine oxidation is of great significance for the study of redox homeostasis in living system.In this review,the development of fluorescent probes for imaging cysteine and cysteine oxidation was summarized.Moreover,we further analyzed defects of the reported fluorescent probes and made suggestions for the future development of fluorescent probes.We expect that this review can not only provide a deeper understanding of the role of cysteine and cysteine oxidation in oxidative stress,but also broaden the application of fluorescent probes in imaging cysteine and cysteine oxidation.

Comprehensive understanding of the superior performance of Sm-modified Fe_(2)O_(3)catalysts with regard to NO conversion and H_(2)O/SO_(2)resistance in the NH_(3)-SCR reaction

Sm-doped Fe_(2)O_(3)catalysts,with a homogeneous distribution of Sm in Fe_(2)O_(3)nanoparticles,were synthesized using a citric acid-assisted sol-gel method.Kinetic studies show that the reaction rate for NO_(x)reduction using the optimal catalyst(0.06 mol%doping of Sm in Fe_(2)O_(3))was nearly 11 times higher than that for pure Fe_(2)O_(3),when calculated based on specific surface area.Furthermore,the Fe_(0.94)Sm_(0.06)O_(x)catalyst maintains>83%NO_(x)conversion for 168 h at a high space velocity in the presence of SO_(2)and H_(2)O at 250℃.A substantial amount of surface-adsorbed oxygen was generated on the surface of Fe_(0.94)Sm_(0.06)O_(x),which promoted NO oxidation and the subsequent fast reaction between NO_(x)and NH_(3).The adsorption and activation of NH_(3)was also enhanced by Sm doping.In addition,Sm doping facilitated the decomposition of NH_(4)HSO_(4)on the surface of Fe_(0.94)Sm_(0.06)O_(x),resulting in its high activity and stability in the presence of SO_(2)+H_(2)O.

Tuning the Water Desalination Performance of Graphenic Layered Nanomaterials by Element Doping and Inter-Layer Spacing

Through atomic molecular dynamics simulations,we investigate the performance of two graphenic materials,boron(BC3)and nitrogen doped graphene(C3 N),for seawater desalination and salt rejection,and take pristine graphene as a control.Effects of inter-layer separation have been explored.When water is filtered along the transverse directions of three-layered nanomaterials,the optimal inter-layer separation is 0.7–0.9 nm,which results in high water permeability and salt obstruction capability.The water permeability is considerably higher than porous graphene filter,and is about two orders of magnitude higher than commercial reverse osmosis(RO)membrane.By changing the inter-layer spacing,the water permeability of three graphenic layered nanomaterials follows an order of C3 N≥GRA>BC3 under the same working conditions.Amongst three nanomaterials,BC3 is more sensitive to inter-layer separation which offers a possibility to control the water desalination speed by mechanically changing the membrane thickness.This is caused by the intrinsic charge transfer inside BC3 that results in periodic distributed water clusters around the layer surface.Our present results reveal the high potentiality of multi-layered graphenic materials for controlled water desalination.It is hopeful that the present work can guide design and fabrication of highly efficient and tunable desalination architectures.

A Selenium Atom Involved Covalent Organic Framework for Window Ledge Photocatalytic Oxidation of Sulfides

Covalent organic frameworks(coFs)driven photocatalytic organic transformations especially photooxidation reactions have become a fertile topic and attracted numerous research attentions.Boosting the charge generation and transport process is the key factor for achieving high catalytic efficiencies.As one of the most effective strategies,the introduction of"heavy atoms"into the long-range ordered conjugated backbones can effectively facilitate the intersystem crossing(isc)process and hence improve the generation of active oxygens,which is beneficial for the oxidation.In this work,we designed and synthesized a benzoselenadiazole based covalent organic framework(COF)material,BSe-COF with heavy atom of selenium(Se),and a benzothiadiazole based BT-COF with isomorphic backbone for comparison.

A combinatorial synthesis method for identification of orally bioavailable cyclic peptide

Cyclic peptides are a type of polypeptide with macrocyclic structure formed by canonical and non-canonical amino acids.Due to their rigid conformation and large surface area,cyclic peptides typically exhibit high binding affinity and specificity with target proteins,particularly those considered undruggable by traditional small molecule drugs,such as protein-protein interactions[1].Additionally,they are convenient to be chemical modified to improve the pharmacological or pharmacokinetic properties.

Carbon dots-based fluorescence sensor for two-photon imaging of pH in diabetic mice

Herein,a reversible pH fluorescent sensor was developed using caffeic acid as the precursor by one-step solvothermal synthesis method.The carbon dots-based sensor(CA-CDs)exhibited pH-dependent increase in fluorescence intensity and showed linear relationship in the range of pH 6.60 and 8.00.Notably,the fluorescence sensor has a reversible response to pH change.Finally,the CA-CDs has been successfully applied for two-photon imaging of the pH in liver and kidney of diabetic mice.Imaging results showed that the pH value in kidney of diabetic mice was lower than that of the normal mice,while the pH value in liver of diabetic mice was almost the same as that of the normal mice.The present study provides a simple analytical method for pH detection suitable for in vivo.

Syntheses and Crystal Structures of Two New Complexes Generated from 2-（（Pyridin-3-ylmethyl）thio）-5-（6-quinolinyl）-1,3,4-oxadiazole and Ag~Ⅰ Salts

Two new Ag~Ⅰ-complexes have been synthesized based on the semi-rigid ligand 2-（（pyridin-3-ylmethyl）thio）-5-（6-quinolinyl）-1,3,4-oxadiazole（L）,obtained by the condensation reaction of 5-（6-quinolinyl）-1,3,4-oxadiazole-2-thiol and 3-chloromethyl pyridine hydrochloride. Crystallization of L with Ag OTf and Ag PF_6 in a CH_2Cl_2/MeO H mixed solvent system at room temperature affords a novel supramolecular [Ag_2L_2（CF_3SO_3）_2]（I） and a coordination polymer [Ag L（PF_6）]_n（Ⅱ）,respectively. Two complexes were characterized by TGA,X-ray powder and single-crystal diffraction.

Synthesis,Crystal Structures and Intermolecular Magnetic Coupling Mechanism of the Mononuclear Radical Complex[1-N-methyl-1,10-phenanthrolium][Ni(dmit)_2]

The mononuclear radical anionic complex [1-N-methyl-1,10-phenanthrolium][Ni（dmit）2]（dmit = 1,3-dithiole-2-thione-4,5-dithiolate） with a new countercation has been prepared and its crystal structure was determined by X-ray crystallography at 298 and 80 K. In the mononuclear radical anionic complex, the nickel ion assumes a slightly distorted square-planar geometry. There are two and three kinds of intermolecular interactions between adjacent mononuclear radical anionic complexes in the crystal at 298 and 80 K, respectively（i.e., Models A and B at 298 K; and Models C, D and E at 80 K）. The variable-temperature magnetic moments indicate a strong antiferromagnetic interaction between the adjacent mononuclear radical anionic complexes, and the theoretical calculations reveal that the stronger antiferromagnetic coupling strength at lower temperature should be contributed to the larger overlap integrals between the short contact atoms. This study is the first to reveal the mechanism of stronger magnetic coupling strength at lower temperature for a mononuclear radical anionic nickel complex with dmit as the ligand.

Intermolecular Magnetic Coupling Mechanism for a New Ionic Pair Salt [Ni（bpy）3][Ni（mnt）2]2

A new ionic pair salt[Ni(bpy)3][Ni(mnt)2]2(mnt=1,2-dicyanoethane-1,2-dithiolate)has been prepared and its crystal structure was determined by X-ray crystallography at 293,200 and 100 K.In the mononuclear radical anionic complex,the nickel ion assumes a slightly distorted square-planar geometry.There is a special kind of stacking interactions at each temperature(i.e.,Model A at 293 K,Model B at 200 K and Model C at 100 K).The variable-temperature magnetic moments indicate that there is a strong anti-ferromagnetic interaction between the adjacent p-p stacking mononuclear radical anionic complexes and especially the anti-ferromagnetic coupling strength is close to the diamagnetism at 100 K.The theoretical calculations reveal for the first time that the spin densities between the short contact atoms areβstate and the anti-ferromagnetic coupling property of this crystal may be related to theβstate spin densities between the short contact atoms.The theoretical calculations further confirm that the strong anti-ferromagnetic coupling strength should be relevant to the larger spin densities on the short contact atoms and the larger overlap integrals between the short contact atoms.

The unique spontaneous polarization property and application of ferroelectric materials in photocatalysis

The unique spontaneous polarization property of ferroelectric material makes it to be a special catalyst in photocatalysis.The spontaneous polarization property can induce the formation of built-in electric field,which can improve the separation of photoelectrons and holes to affect photocatalytic performance.The internal electric field induced by spontaneous polarization can be influenced by multiple factors such as the morphology,the concentration of defect,the type of doped heteroatoms,as well as the composition of heterostructures.Besides,the preparation method,pretreating temperature,the strength of prepolarized external electric field of ferroelectric-based photocatalysts as well as the strength of external mechanical force or external magnetic field in photocatalytic reactions can influence the photocatalytic effectivity via influencing spontaneous polarization-induced internal electric field.Thus,it is urgently to unveil the mystery of structure-activity relationships for ferroelectric materials-based photocatalysts,which is usually uncertain.With this in mind,this review was provided for the role of various complex influencing factors on ferroelectric materials-based photocatalysis based on the latest advancement in the fields of new energy development,environmental remediation.In the beginning,the basic structure and properties of ferroelectric material are given.Then,popular synthesis methods of ferroelectric-based photocatalysts are summarized.After that,two main mechanisms of ferroelectric photocatalysis are discussed.The research progress of ferroelectric photocatalysis is then given emphatically according to the classification of photocatalytic reactions.Finally,the problems existing nowadays and the challenges facing in the future on the application of ferroelectric materials-based photocatalysts are outlined in the summary and outlook section.

Tracking interactions between TAMs and CAFs mediated by arginase-induced proline production during immune evasion of HCC

Synergistic changes between tumor-associated macrophages(TAMs)and cancer-associatedfibroblasts(CAFs)aggravated immune evasion of hepatocellular carci-noma(HCC),however,the underlying molecular mechanisms remain elusive.Their continuous and dynamic interactions are subject to bioactive molecule changes.A real-time and in situ monitoring method suitable for in vivo research of these processes would be indispensable but is scarce.In this study,a dual imaging strat-egy that tracing the TAMs and CAFs simultaneously was developed using a new arginase-specific probe and established CAFs-specific probe.The emerging roles of arginase in mediating CAFs activation in mice were explored.Results showed arginase up-regulation in TAMs,followed by proline increase.Subsequently,proline produced by TAMs initiated the activation of CAFs.Through the JAK-STAT sig-naling,CAFs up-regulated the PD-L1 and CTLA-4,ultimately promoting immune evasion of HCC.This study revealed a new mechanism by which TAMs and CAFs collaborate in immune evasion,providing new targets for HCC immunotherapy.

Rapid and Scalable Synthesis of Prussian Blue Analogue Nanocubes for Electrocatalytic Water Oxidation

Design and fabrication of earth-abundant electrocatalysts for oxygen evolution reaction(OER)is essential in improving the overall ef-ficiency of water electrolysis.In this work,we proposed a rapid and scalable synthesis route for fabricating Prussian blue analogue(PBA)nano cubes with tun able compositi ons and uniform particle size.With the structural ben efits of abu ndant surface sites,facile charge transfer behavior and favorable Co^(2+)-to-Co^(3+)pre-oxidation reaction,fast generation and accumulation of the catalytically active Co3+sites can be achieved for the CoCo PBA nano cubes,leadi ng to remarkable OER activity with simulta neously achieved low overpotential,large anodic current density,small Tafel slope as well as outstanding intrinsic activity.Of note,by performing Iong-term OER operati on,the CoCo PBA nano cubes exhibit a remarkable 5.5-folds performs nee enhan ceme nt,and obvious surface rec on struc-tion and the accumulation of high-valence Co species can be identified,proving the crucial role of pre-oxidation process in boosting the OER catalysis.This work proposed a un iversal approach for the rapid,scalable and con trollable fabricati on of the PBA-based materials,and the elucidation of the pre-oxidation process in facilitating the OER catalysis may provide useful guidanee for designing and optimizing advanced catalysts for energy-related electro-oxidation reactions in the future.

A Double Helix Coordination Polymer Generated from 2-（（Pyridin-4-ylmethyl）thio）-5-（quinoline-2-yl）-1,3,4-oxadiazole and Ag^Ⅰ Salts

The new ligand 2-（（pyridin-4-ylmethyl）thio）-5-（quinoline-2-yl）-1,3,4-oxadiazole（L） and Ag Cl O4 produced a new coordination polymer： [（Ag2L2Cl O4）ClO 4]n（1）. The complex has been characterized by single-crystal X-ray diffraction, IR, TGA, PXRD, UV and elemental analysis. Compound 1 crystallizes in triclinic system, space group P1, with a = 8.4593（5）, b = 14.5903（9）, c = 15.7908（10） A, α = 97.357（5）, β = 99.116（5）, γ = 104.470（5）°, V = 1834.43（20） A3, Dc = 1.91056 g/cm^3, Mr = 1055.38, Z = 2, F（000） = 1048, u = 1.399 mm-1, the final S = 1.002, R = 0.049 and wR = 0.105. The compound consists of a double helix chain. The neighboring chains interact via two kinds of π-π interactions to form a two-dimensional（2D） sheet. Each sheet interacts with the neighboring sheets via π-π interactions to form an extended 3D supramolecular network.

Nanoscale covalent organic framework for the low-temperature treatment of tumor growth and lung metastasis

Photothermal therapy(PTT)has shown promising applications in tumor therapies.However,due to laserinduced nonspecific heating and heat diffusion,high levels of hyperthermia(>50℃)in tumor tissues often increase the risk of cancer recurrence and metastasis,which causes the patient pain and destroys the surrounding normal cells and tissues.It is therefore important to develop photothermal strategies that have excellent therapeutic efficiencies under low-temperature conditions(≤45℃).In addition,the heterogeneity and complexity of tumors require the development of combinatorial antitumor treatments as the therapeutic efficiency of monomodal PTT is not currently sufficient.Herein,we have adopted a stepwise synthetic approach to develop a highly efficient multimodal therapeutic agent GA@PCOF@PDA by successive bonding defect functionalization(BDF),guest encapsulation,and surface modification steps.The covalently grafted porphyrinic photosensitizers(Por),encapsulated gambogic acid(GA),and surface-modified PDA film are independently responsible for photodynamic therapy(PDT),heat-shock protein 90(HSP90)down-regulation and chemotherapy(CT),and low-temperature PTT.This proof-ofconcept study illustrates an efficient,generalized approach to design high-performance covalent organic framework(COF)-based nanoagents that can be easily tailored to combine different therapeutic modalities for improved cancer theranostics at low temperatures.

Air-Processed Efficient Organic Solar Cells from Aromatic Hydrocarbon Solvent without Solvent Additive or Post-Treatment:Insights into Solvent Effect on Morphology

Most of the recent organic solar cells(OSCs)with top-of-the-line efficiencies are processed from organic solvents with a high vapor pressure such as CF in nitrogen-filled glovebox,which is not feasible for large-area manufacturing.Herein,we cast active layers with both aromatic hydrocarbon solvents and halogenated solvents without any solvent additive or post-treatment,as well as interlayers with water and methanol in air(35%relative humidity)for efficient OSCs,except cathode electrode's evaporation is in vacuum.Compared to the PM6:Y6 system that is processed from CF,the PM6:BTP-ClBr2 system demonstrates good efficiency of 16.28%processed from CB and the device based on PM6:BTP-4Cl achieves 16.33%using TMB as its solvent for the active layer.These are among the highest efficiencies for CB-and TMB-processed binary OSCs to date.The molecular packing and phase separation length scales of each combination depend strongly on the solvent,and the overall morphology is the result of the interplay between solvent evaporation(kinetics)and materials miscibility(thermodynamics).Different solvents are required to realize the optimal morphology due to the different miscibility between the donor and acceptor.Finally,17.36%efficiency was achieved by incorporating PC71BM for TMB-processed devices.Our result provides insights into the effect of processing solvent and shows the potential of realizing high-performance OSCs in conditions relevant for industrial fabrication.

Removal of toxic metal ions using chitosan coated carbon nanotube composites for supercapacitors

Environmental pollution and energy crisis are two major global challenges to human beings.Recovering energy from wastewater is considered to be one of the effective approaches to address these two issues synchronously.As the main pollutants in wastewater,toxic heavy metal ions are the potential candidates for energy storage devices with pseudocapacitive behaviors.In this study,toxic metal ions of Cr(VI)and Cu(II)are removed efficiently by chitosan coated oxygen-containing functional carbon nanotubes,and the corresponding equilibrium adsorption capacity is 142.1 and 123.7 mg g^(-1).Followed by carbonization of metal ions-adsorbed adsorbents,Cu-and Cr N-loaded carbon composites can be obtained.Electrochemical measurements show that the supercapacitor electrodes based on Cu-and Cr N-loaded carbon composites have specific capacitance of 144.9 and 114.9 F g^(-1)at2 m V s^(-1),with superior electrochemical properties to pure chitosan coated carbon nanotubes after carbonization.This work demonstrates a new strategy for the resource-utilization of other heavy metal ions for energy devices,and also provides a new way to turn environmental pollutants into clean energy.

Simultaneous bioimaging of MMP-2 and MMP-7 via Au-Se constructed fluorescence nanoprobe

Au-Se bond strategy has been applied to construct fluorescence nanoprobe that is being used to simultaneously dual-image the tumor markers matrix metalloproteinase-2(MMP-2)and matrix metalloproteinase-7(MMP-7)in vitro.The two Se-terminating ligand peptide chains respectively labeled with fluorescein isothiocyanate(FITC)and 5-Carboxytetramethylrhodamine(5-TAMRA)dyes are attached to the surface of Au nanoparticles(NPs).The nanoprobe can be specifically cut off by MMP-2 and MMP-7 respectively to carry out significant enhanced fluorescence recovery for simultaneously imaging both markers.The nanoprobe not only displays high selectivity and sensitivity towards MMP-2 and MMP-7,but also has strong anti-interference stability against biothiols and enhanced fidelity for avoiding"false positive"results.This approach offers new perspectives in designing tumor-related early diagnosis approaches and also provides strategies for clinical applications.

Metal-induced Coordination Networks Using a C2v-based Hexacarboxylate Ligand:Syntheses, Structures and Properties

Metal-organic frameworks(MOFs), consisting of metal, anion and organic ligands, have attracted much attention. The structure of MOFs is affected by various factors. To explore the effects of metal ions, we synthesized six complexes, namely {[Me2NH2][Zn4(H2L)(L)]·2 H2O·2 DMF}n(1), {[Me2NH2]2[Cd2(L)]·2H2O}n(2), {[Me2NH2]2[Ca3(L)(μ-OH)2(DMF)2]·2H2O}n(3) and {[Me2NH2]2[M2(L)(μ-OH)]· H2O·2DMF}n(M = Co, 4;Ni, 5;Mn, 6), from a C2v-based hexacarboxylate ligand([1,1’;4’,1’’]terphenyl-3,5,2’,5’,3’’,5’’-hexacarboxylic acid(H6L)) using metal-induced strategy. These MOFs were thoroughly characterized by single-crystal and X-ray diffraction, elemental analysis, Fourier-transform infrared spectra(FTIR) and photoluminescence.

In-situ assembly of 2D/3D porous nickel cobalt sulfide solid solution as superior pre-catalysts to boost multi-functional electrocatalytic oxidation

In this work,we fabricated an efficient pre-catalyst based on(Ni,Co)S2solid solution with hierarchical architecture and high porosity to boost urea oxidation reaction and electrocatalytic oxidation of organic small molecules.The interaction between Ni and Co can optimize the electronic structure,resulting in the improved conductivity and accelerated charge transfer rate.The 2D/3D architecture can enrich more active species and endow the mass and electron transport to facilitate the surface oxidation and the following catalytic process.Post-structure and catalytic characterizations confirm the surface oxidation of(Ni,Co)S_(2)during the stability test,and the in-situ formed Co(Ni)based(oxy)hydroxides exhibit superior catalytic activity and facilitated charge transfer ability.As a result,the optimal(Ni,Co)S_(2)solid solution pre-catalyst displays facilitated catalytic behavior and good stability for multifunctional electrocatalytic oxidation,in which a high conversion of benzyl alcohol(97.50%),a good selectivity to benzoic acid(93.78%)and a satisfied faraday efficiency(91.86%)can be achieved.

Porphyrin covalent organic framework for photocatalytic synthesis of tetrahydroquinolines

A metal-free porphyrin covalent organic framework was employed as the heterogeneous photocatalyst for the synthesis of tetrahydroquinolines under aerobic conditions.With visible light irradiation of a catalytic amount of H_(2)P-Bph-COF at room temperature,various substituted N,N-dimethylanilines and N-aryl maleimides were transformed to tetrahydroquinoline derivatives in moderate to good yields.This was the first example of the synthesis of tetrahydroquinolines via the photocatalytic aerobic annulation reaction employing the metal-free COF as the heterogeneous photocatalyst.