Composition Engineering Opens an Avenue Toward Efficient and Sustainable Nitrogen Fixation

In this work,we open an avenue toward rational design of potential efficient catalysts for sustainable ammonia synthesis through composition engineering strategy by exploiting the synergistic effects among the active sites as exemplified by diatomic metals anchored graphdiyne via the combination of hierarchical high-throughput screening,first-principles calculations,and molecular dynamics simulations.Totally 43 highly efficient catalysts feature ultralow onset potentials(|U_(onset)|≤0.40 V)with Rh-Hf and Rh-Ta showing negligible onset potentials of 0 and-0.04 V,respectively.Extremely high catalytic activities of Rh-Hf and Rh-Ta can be ascribed to the synergistic effects.When forming heteronuclears,the combinations of relatively weak(such as Rh)and relatively strong(such as Hf or Ta)components usually lead to the optimal strengths of adsorption Gibbs free energies of reaction intermediates.The origin can be ascribed to the mediate d-band centers of Rh-Hf and Rh-Ta,which lead to the optimal adsorption strengths of intermediates,thereby bringing the high catalytic activities.Our work provides a new and general strategy toward the architecture of highly efficient catalysts not only for electrocatalytic nitrogen reduction reaction(eNRR)but also for other important reactions.We expect that our work will boost both experimental and theoretical efforts in this direction.

Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography

A novel method for the determination of five carbamate pesticides （metolcarb, carbofuran, carbaryl, isoprocard and diethofencard） in water samples was developed by dispersive liquid-liquid microextraction （DLLME） coupled with high performance liquid chromatography-diode array detector （HPLC-DAD）. Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL^-1 for all the five carbamate pesticides, with the correlation coefficients （r^2） varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177- fold, depending on the compound. The limits of detection （LODs） （S/N = 3） were ranged from 0.1 to 0.5 ng mL^-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.

Recent progress of nanotechnology-based theranostic systems in cancer treatments

Theranostics that integrates therapy and diagnosis in one system to achieve accurate cancer diagnosis and treatment has attracted tremendous interest,and has been recognized as a potential breakthrough in overcoming the challenges of conventional oncotherapy.Nanoparticles are ideal candidates as carriers for theranostic agents,which is attributed to their extraordinary physicochemical properties,including nanoscale sizes,functional properties,prolonged blood circulation,active or passive tumor targeting,specific cellular uptake,and in some cases,excellent optical properties that ideally meet the needs of phototherapy and imaging at the same time.Overall,with the development of nanotechnology,theranostics has become a reality,and is now in the transition stage of"bench to bedside."In this review,we summarize recent progress on nanotechnology-based theranostics,i.e.,nanotheranostics,that has greatly assisted traditional therapies,and has provided therapeutic strategies emerging in recent decades,as well as"cocktail"theranostics mixing various treatment modalities.

Determination of triazine herbicide residues in water samples by on-line sweeping concentration in micellar electrokinetic chromatography

A new method for the determination of atrazine, simazine and prometryn in water samples by on-line sweeping concentration technique in micellar electrokinetic chromatography （MEKC） was developed. Various parameters affecting sample enrichment and separation efficiency were systematically studied. Compared with the conventional MEKC method, up to 60-200-fold improvement in concentration sensitivity was achieved in terms of peak height by using this sweeping injection technique. The compound strychnine was used as the internal standard for the improvement of the experimental reproducibility. The limits of detection （S/ N = 3：1） for atrazine, simazine and prometryn were 9, 10 and 0.5 ng mL-1, respectively. This method has been successfully applied to the analysis of atrazine, simazine and prometryn in lake, steam and ground water.

An efficient synthesis of 1,5-benzodiazepine derivatives catalyzed by boric acid

1,5-Benzodiazepine derivatives have been synthesized by the condensation of o-phenylenediamines and ketones in the presence of boric acid as catalyst under mild conditions. This method is simple, environmentally benign and high yielding. ？2009 Chun Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Time-Programmed Delivery of Sorafenib and Anti-CD47 Antibody via a Double-Layer-Gel Matrix for Postsurgical Treatment of Breast Cancer

The highly immunosuppressive microenvironment after surgery has a crucial impact on the recurrence and metastasis in breast cancer patients.Programmable delivery of immunotherapy-involving combinations through a single drug delivery system is highly promising,yet greatly challenging,to reverse postoperative immunosuppression.Here,an injectable hierarchical gel matrix,composed of dual lipid gel(DLG)layers with different soybean phosphatidylcholine/glycerol dioleate mass ratios,was developed to achieve the time-programmed sequential delivery of combined cancer immunotherapy.The outer layer of the DLG matrix was thermally responsive and loaded with sorafenib-adsorbed graphene oxide(GO)nanoparticles.GO under manually controlled near-infrared irradiation generated mild heat and provoked the release of sorafenib first to reeducate tumor-associated macrophages(TAMs)and promote an immunogenic tumor microenvironment.The inner layer,loaded with anti-CD47 antibody(aCD47),could maintain the gel state for a much longer time,enabling the sustained release of aCD47 afterward to block the CD47-signal regulatory proteinα(SIRPα)pathway for a long-term antitumor effect.In vivo studies on 4T1 tumor-bearing mouse model demonstrated that the DLG-based strategy efficiently prevented tumor recurrence and metastasis by locally reversing the immunosuppression and synergistically blocking the CD47-dependent immune escape,thereby boosting the systemic immune responses.

On-line Sweeping Sample Concentration in Micellar Electrokinetic Chromatography with Enhanced Sensitivity for the Deter-mination of Carbamazepine in Human Serum

A sensitive and simple micellar electrokinetic chromatography （MEKC） method was developed for the determination of antiepileptic drug, carbamazepine （CBZ）, using sweeping on-line concentration method with photodiode array detection. Under the optimal conditions, the calibration curve was linear over a range of 0.5-40μg·mL^-1 for CBZ with a correlation coefficient of 0.998. The detection limit （S/N = 3：1） of CBZ was 0.10 μg·mL^-1. The sweeping-MEKC method has been successfully applied to the analysis of CBZ in human serum.

Antioxidant activity of polyaniline nanofibers

Well-confined uniform polyaniline （PANI） nanofibers were synthesized by using photo-assisted chemical oxidative polymer- ization of aniline in the presence of different dopant acids, and the radical scavenging ability of the produced PANI nanofibers was determined by the DPPH assay. It was found that the antioxidant activity of PANI nanofibers was higher than conventional PANI, and increased with decreasing of averaged diameter of the nanofibers. The enhanced antioxidant activity was concerned with increased surface area of PANI nanofibers.

Combination of hollow fiber-based liquid-phase microextraction with sweeping techniques in micellar electrokinetic chromatography for the determination of Strychnos alkaloids in human urine

A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextxaodon （LPME） based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinodc chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL^-1 for both strychnine and brucine in human urine sample. The detection limits （S/N = 3：1） for strychnine and brucine were 1 ng mL^-1 and 2 ng mL^-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.

Unveiling the Underlying Mechanism of Transition Metal Atoms Anchored Square Tetracyanoquinodimethane Monolayers as Electrocatalysts for N_(2) Fixation

We for the first time systematically studied the structures and electrochemical nitrogen reduction reaction properties of two-dimensional single transition-metal anchored square tetracyanoquinodimethane monolayers(labeled as:TM-sTCNQ,TM=3d,4d,5d series transition metals)by employing density functional theory method.Through highthroughput screenings and full reaction path researches,two promising electrochemical nitrogen reduction reaction catalysts Nb-sTCNQ and MosTCNQ have been obtained.The nitrogen reduction reaction onset potential on Nb-sTCNQ is as low as−0.48 V.Furthermore,the Nb-sTCNQ catalyst can quickly desorb NH3 produced with a free energy of 0.65 eV,giving Nb-sTCNQ excellent catalytic cycle performance.The high catalytic activity of the two materials might be attributed to the effective charge transfer between the active center and adsorbed N_(2),which enables the active center to adsorb and activate inert N_(2) molecules well,and the reduction processes require small energy input(i.e.,the maximum free energy changes are small).This work provides insights for finding highly efficient,stable,and low-cost nitrogen reduction reaction electrocatalysts.We hope our results can promote further experimental and theoretical research of this field.

Two-Dimensional Organometallic TM3–C12S12 Monolayers for Electrocatalytic Reduction of CO2

Organometallic nanosheets are a versatile platform for design of efficient electrocatalyst materials due to their high surface area and uniform dispersion of metal active sites.In this paper,we systematically investigate the electrocatalytic performance of the first transition metal series TM3–C12S12 monolayers on CO2 using spin-polarized density functional theory.The calculations show that M3–C12S12 exhibits excellent catalytic activity and selectivity in the catalytic reduction in CO2.The main reduction products of Sc,Ti,and Cr are CH4.V,Mn,Fe and Zn mainly produce HCOOH,and Co produces HCHO,while CO is the main product for Ni and Cu.For Sc,Ti,and Cr,the overpotentials are>0.7 V,while for V,Mn,Fe,Co,Ni,Cu,Zn,the overpotentials are very low and range from 0.27 to 0.47 V.Therefore,our results indicate that many of the M3–C12S12 monolayers are expected to be excellent and efficient CO2 reduction catalysts.

Multifunctional properties of a polar spin chain compound[N(C_(3)H_(7))_(4)][Cu(C_(8)H_(4)NO_(4))]·H_(2)O exhibiting both one-dimensional magnetism and nonlinear optical activity

Functional materials with multiple properties are urgent to be explored to reach high requirements for applications nowadays.In this work,a new multifunctional one-dimensional(1D)chain compound[N(C_(3)H_(7))_(4)][Cu(ohpma)]·H_(2)O 1(ohpma=deprotonated N-(2-hydoxyphenyl)oxamic acid)exhibiting both 1D antiferromagnetic and nonlinear optical properties,which are both originated from the same polar[Cu(C_(8)H_(4)NO_(4))]magnetic units,has been successfully synthesized by evaporation at room temperature.Bis-polydentate nature of the(ohpma)3−ligand with constrained tridentate and bidentate coordination sites conducts Cu^(2+)ions coordinating in different geometries and forms 1D chains along the c axis,which are further separated by the[N(C_(3)H_(7))_(4)]+cations.And the 1D magnetic chains further exhibit noncentrosymmetric polar arrangement.Nonlinear optical study shows polar compound 1 exhibits a discernible second-harmonic generation(SHG)efficiency and the calculation of the partial density of states indicates that the SHG efficiency of 1 is mainly originated from the polar[Cu(C_(8)H_(4)NO_(4))]magnetic units.Moreover,magnetic susceptibility shows a broad maximum around 70 K with strong intrachain interaction of J/k B=−113.0 K but no long-range order is observed down to 2 K,suggesting that 1 shows a good 1D magnetism.Both good 1D magnetism and SHG activity suggest that 1 could be as a potential multifunctional material,particularly.

Tumor-repopulating cell-derived microparticles elicit cascade amplification of chemotherapy-induced antitumor immunity to boost anti-PD-1 therapy

Immune checkpoint blockade(ICB)therapy,particularly antibodies targeting the programmed death receptor 1(PD-1)and its ligand(PD-L1),has revolutionized cancer treatment.However,its efficacy as a standalone therapy remains limited.Although ICB therapy in combination with chemotherapy shows promising therapeutic responses,the challenge lies in amplifying chemotherapy-induced antitumor immunity effectively.This relies on efficient drug delivery to tumor cells and robust antigen presentation by dendritic cells(DCs).Here,we developed tumor-repopulating cell(TRC)-derived microparticles with exceptional tumor targeting to deliver doxorubicin(DOX@3D-MPs)for improve anti-PD-1 therapy.DOX@3D-MPs effectively elicit immunogenic tumor cell death to release sufficient tumor antigens.Heat shock protein 70(HSP70)overexpressed in DOX@3D-MPs contributes to capturing tumor antigens,promoting their phagocytosis by DCs,and facilitating DCs maturation,leading to the activation of CD8+T cells.DOX@3D-MPs significantly enhance the curative response of anti-PD-1 treatment in large subcutaneous H22 hepatoma,orthotopic 4T1 breast tumor and Panc02 pancreatic tumor models.These results demonstrate that DOX@3D-MPs hold promise as agents to improve the response rate to ICB therapy and generate long-lasting immune memory to prevent tumor relapse.

The immune-chemo-embolization effect of temperature sensitive gold nanomedicines against liver cancer

Although transcatheter arterial chemo-embolization(TACE)plays a key role on clinical treatment of hepatocellular carcinoma(HCC),it was greatly limited by the poor synergistic effect between chemotherapeutics and physical embolization to tumor-feeding arteries.In the present work,a temperature sensitive polymer poly(N-isopropylacrylamide-b-methacrylic acid)(PNA),which was modified with gold nanoparticles(AuNP@PNA),was successfully used to encapsulate doxorubicin(DOX)by electrostatic binding with their carboxyl groups.The resultant gold nanomedicines(AuNP@PNA/DOX)exhibited temperature responsive sol-gel phase transition,favorable shear thinning effect and X-ray angiography.By in vivo evaluation of vascular embolization on VX2-tumor-bearing rabbits,AuNP@PNA/DOX exhibited far better antitumor efficacy than Lipiodol/DOX,on either tumor growth inhibition,proliferation,apoptosis,necrosis or anti-metastasis.Owing to sufficient embolization to tumor vascular networks,AuNP@PNA/DOX down-regulated the expression levels of HIF-1α,VEGF and MMP-9,and prompted more efficient activation on CD3+/CD8+T cells and the related cytokines,suggesting the synergistic effect between AuNP@PNA and DOX on the improvement of post-operative tumor immunosuppressive microenvironment.With their favorable pharmcokinetics and biocompatibility,AuNP@PNA/DOX is promising to be developed as a multi-functional artery-imaging/embolic agent with immune-chemo-embolization for enhancing TACE efficacy on HCC.

Decarboxylative cyanation and thiocyanation via catalytic electron donor-acceptor complex with copper catalysis

A new catalytic decarboxylative cyanation and thiocyanation via a synergistic Na I/Cu catalysis is developed.The photoexcited electron donor-acceptor complex by assembly of Na I,R3P,and N-acyloxy-phthalimide ester(NHPI ester)triggers the generation of alkyl radical species,which then engages in Cu-catalyzed radical coupling process.Key to success of this dual catalytic transformation is the reliable charge transfer between I·and Cu(I).This dual catalytic platform can eliminate the use of expensive iridium-based photocatalyst or synthetically elaborate organic dyes.A series of primary,secondary,and tertiary alkyl nitriles and thiocyanates are easily synthesized.Moreover,an asymmetric decarboxylative cyanation by applying a chiral Cu catalyst is also developed to afford chiral nitriles in high enantioselectivity.The mechanistic details and the origin of the high enantioselectivity are further investigated by the mechanistic experiments and the density functional theory calculations.

Atomic-iodine-substituted polydiacetylene nanospheres with boosted intersystem crossing and nonradiative transition through complete radiative transition blockade for ultraeffective phototherapy

The energy dissipation pathways of a photosensitizer for phototherapies,including photodynamic therapy(PDT)and photothermal therapy(PTT),compete directly with that of itsfluorescence(FL)emission.Enriching heavy atoms on theπ-conjugated systems and aggregation-caused quenching are two effective methods to turn off the FL emission of photosensitizers,which is expected to boost the inter-system crossing(for PDT)and nonradiative transition(for PTT)of photosensitizers for maximized phototherapeutic efficacy.Following this approach,an all-iodine-substituted polydiacetylene aggregate poly(diiododiacetylene)(PIDA)has been developed,which shows a superior near infrared absorption(ε_(808nm)=26.1 g^(-1) cm^(-1) L)with completely blocked FL,as well as high efficiency of reactive oxygen species generation(nearly 45 folds of indocyanine green)and photothermal conversion(33.4%).To make the insolublefibrillar PIDA aggregates favorable for systemic administration,they are converted into nanospheres through a pre-polymerization morphology transformation strategy.The in vivo study on a 4T1 tumor-bearing mouse model demonstrates that PIDA nanospheres can almost eliminate the tumor entirely in 16 days and prolong the survival time of mice to over 60 days,validating their effective phototherapeutic response through the strategy of inhibiting FL for boosted intersystem crossing and nonradiative transition.

Unimolecular Self-Assembled Hemicyanine-Oleic Acid Conjugate Acts as a Novel Succinate Dehydrogenase Inhibitor to Amplify Photodynamic Therapy and Eliminate Cancer Stem Cells

Photodynamic therapy with reactive oxygen species production is a prospective treatment to combat cancer stem cells(CSCs).However,the innate drawbacks,including short lifetime and diffusion distance of reactive oxygen species and hypoxia within solid tumors,have become bottlenecks for clinical applications of photodynamic therapy.Here,we develop a mitochondria-targeting hemicyanine-oleic acid conjugate(CyOA),which can self-assemble into supramolecular nanoparticles(NPs)without any exogenous excipients.CyOA is also shown for targeting the mitochondrial complex II protein succinate dehydrogenase to inhibit oxidative phosphorylation and reverse tumor hypoxia,resulting in 50.4-fold higher phototoxicity against breast cancer stem cells(BCSCs)compared to SO_(3)-CyOA NPs that cannot target to mitochondria.In 4T1 and BCSC tumor models,CyOA NPs achieve higher tumor inhibition and less lung metastasis nodules compared to the clinically used photosensitizer Hiporfin.This study develops a self-assembled small molecule that can serve as both oxidative phosphorylation inhibitor and photosensitizer for eradication of CSCs and treatment of solid tumors.

A novel method for the determination of trace copper in cereals by dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with flame atomic absorption spectrometry

A novel,simple,rapid,efficient and environment-friendly method for the determination of trace copper in cereal samples was developed by using dispersive liquid-liquid microextraction based on solidification of floating organic drop（DLLME-SFO） followed by flame atomic absorption spectrometry.In the DLLME-SFO,copper was complexed with 8-hydroxy quinoline and extracted into a small volume of 1-dodecanol,which is of low density,low toxicity and proper melting point near room temperature. The experimental parameters affecting the extraction efficiency were investigated and optimized.Under the optimum conditions, the calibration graph exhibited linearity over the range of 0.5—500 ng/mL with the correlation coefficient（r） of 0.9996.The enrichment factor was 122 and the limit of detection was 0.1 ng/mL.The method was applied to the determination of copper in the complex matrix samples such as rice and millet with the recoveries for the spiked samples at 5.0 and 10.0 u,g/g falling in the range of 92.0-98.0%and the relative standard deviation of 3.9-5.7%.

A highly sensitive DNA-AIEgen-based ＂turn-on＂ fluorescence chemosensor for amplification analysis of Hg^2+ ions in real samples and living cells

Functional nucleic acids(FNAs)-based biosensors have shown great potential in heavy metal ions detection due to their low-cost and easy to operate merits. However, in most FNAs based fluorescence probes, the ingenious designs of double-labeled(fluorophore and quencher group) DNA sequence, not only bring the annoyance of organic synthesis, but also restrict its use as a robust biosensor in practical duties. In this paper, we design a simple AIEgens functional nucleic acids(AFNAs) probe which consists of only fluorogen but no quencher group. With the help of duplex-specific nuclease(DSN) enzyme based target recycling, high fluorescence signal and superior sensitivity towards Hg^(2+) are achieved. This robust assay allows for sensitive and selective detection of Hg^(2+) in real water samples and mapping of intracellular Hg^(2+), without double-labeling of oligonucleotide with a dye-quencher pair, nor the multiple assay steps.

Analyte-responsive fluorescent probes with AIE characteristic based on the change of covalent bond

It is important for the determination of biologically and/or environmentally relevant species by utilization of fluorescent probes. Conventional fluorescent probes are subjected to the influence of aggregation-caused quenching that is limiting their application due to low selectivity as well as photobleaching. Additionally, quencher pairs are usually introduced in the design of these probes, which lead to the complex synthetic procedure. A novel class of fluorogens with aggregation-induced emission (AIE) characteristic provide a solution to address the dilemma. By taking advantage of the unique characteristic of AIE fluorogens, specific turn-on probes have been developed via combination with recognition components, exhibiting low background, good selectivity and outstanding photostability. This review focuses on the development of fluorescent probes with AIE characteristics via the bond cleavage as well as formation strategy.