Magnetic metals （Fe, Co, Ni） and alloys thereof are easily synthesized as nanoparticles, but obtaining highly dispersed graphene-based magnetic nanomaterials remains challenging. Here, three CoNi/graphene nanocompos...Magnetic metals （Fe, Co, Ni） and alloys thereof are easily synthesized as nanoparticles, but obtaining highly dispersed graphene-based magnetic nanomaterials remains challenging. Here, three CoNi/graphene nanocomposites （CoNi/GN） are successfully assembled for the first time via a one-pot strategy without templating by manipulating the reaction time and solvents used for the same precursors. Moreover, the reduction of graphene oxide utilizing this method is more effective than that by conventional methods and the alloy particles are firmly embedded on the GN substrate. Compared to n- and p-CoNi/GN nanocomposites, o-CoNi/GN nanocomposites show the best electromagnetic wave absorption properties with the maximum reflection loss of -31.0 dB at 4.9 GHz for a thickness of 4 mm; the effective absorption bandwidth （〈 10.0 dB） is 7.3 GHz （9.5-16.8 GHz） for a thickness of 2 mm. The structures and electromagnetic wave absorption mechanisms of the three composites were also investigated. This research provides a new platform for the development of magnetic alloy nanoparticles in the field of microwave-absorbing devices.展开更多
Metallic silver （Ag） and its ability to combat infection have been known since ancient history. In the wake of nanotechnology advancement, silver＇s efficacy to fight broad spectrum bacterial infections is further i...Metallic silver （Ag） and its ability to combat infection have been known since ancient history. In the wake of nanotechnology advancement, silver＇s efficacy to fight broad spectrum bacterial infections is further improved in the form of Ag nanoparticles （NPs）. Recent studies have ascribed the broad spectrum antimicrobial properties of Ag NPs to dissociation of Ag＊ ions from the NPs, which may not be entirely applicable when the size of Ag NPs decreases to the sub-2 nm range [denoted Ag nanoclusters （NCs）]. In this paper we report that ultrasmall glutathione （GSH）-protected Ag^＋-rich NCs （Ag^＋-R NCs for short, with a predominance of Ag＋ species in the NCs） have much higher antimicrobial activities towards both gram-negative and gram-positive bacteria than the reference NC, GSH-Ag^＋-R NCs. They have the same size and surface ligand, but with different oxidation states of the core silver. This interesting finding suggests that the undissociated Ag^＋-R NCs armed with abundant Ag^＋ ions on the surface are highly active in bacterial killing, which was not observed in the system of their larger counterpart, Ag NPs.展开更多
In this paper, the DNA-templated Ag/Pt bimetallic nanoclusters were successfully synthesized using an optimized synthetic scheme. The obtained DNA-Ag/Pt NCs have an ultrasmall particle size and excellent distribution....In this paper, the DNA-templated Ag/Pt bimetallic nanoclusters were successfully synthesized using an optimized synthetic scheme. The obtained DNA-Ag/Pt NCs have an ultrasmall particle size and excellent distribution. The DNA-Ag/Pt NCs show intrinsic peroxidase-mimicking activity and can effectively catalyze the H2O2-mediated oxidation of a substrate, 3,30,5,50-tetramethylbenzidine（TMB）, to produce a blue colored product. Based on this specific property, we employed the aptamer of VEGF to design a label-free electrochemical biosensor for VEGF detection. Under the optimized experimental conditions, a linear range from 6.0 pmol/L to 20 pmol/L was obtained with a detection limit of 4.6 pmol/L. The proposed biosensor demonstrated its high specificity for VEGF and could directly detect the VEGF concentration in human serum samples of breast cancer patients with satisfactory results. This novel electrochemical aptasensor was simple and convenient to use and was cost-effective and label-free in design, and would hold potential applications in medical diagnosis and treatment.展开更多
Single atom catalysts(SACs)were reported to demonstrate exciting catalytic features for a number of reactions,including hydrogen evolution reaction(HER).However,the true role of these single atom sites in catalysts re...Single atom catalysts(SACs)were reported to demonstrate exciting catalytic features for a number of reactions,including hydrogen evolution reaction(HER).However,the true role of these single atom sites in catalysts remains elusive,particularly for those prepared via pyrolysis,where the formation of active nanoparticle counterparts is often unavoidable.Here we report a Ru based catalyst(Ru embedded in N doped carbon spheres(Ru/NPCS))comprising of both Ru nanoclusters and Ru single sites,who demonstrates activity exceeding Pt catalyst and mass activity among the best of the Ru based catalysts under acidic conditions.The integration of proton exchange membrane water electrolysis with Ru/NPCS as a cathode exhibited an excellent hydrogen generation activity and extraordinary stability(during 120 h of electrolysis)with a 1/48 Ru loading(16.5μgRu·cm^(−2))of a commercial 20%Pt/C catalyst.Through precisely tailoring the dispersion status of the catalysts,we reveal that while ruthenium nanoclusters actively catalyze HER via Volmer–Tafel mechanism,the Ru SACs barely catalyze HER,with H*adsorption difficult to occur.Moreover,no synergy between Ru SACs and Ru cluster is revealed,meaning the Ru SACs act as a spectator rather than active species during H2 evolution.展开更多
Atomically precise gold(Au)nanoclusters(NCs)as visible light photosensitizers supported on the substrate for photoredox catalysis have attracted considerable attentions.However,eficient control of their photocatalytic...Atomically precise gold(Au)nanoclusters(NCs)as visible light photosensitizers supported on the substrate for photoredox catalysis have attracted considerable attentions.However,eficient control of their photocatalytic activity and long-term stability is still challenging.Herein,we report a coordination-assisted self-assembly strategy in combination with electrostatic interaction to sandwich Au2:(Capt)18(abbreviated as AU25,Capt=captopril)NCs between an inner core and an outer shell made of UiO-66,denoted as UiO-66@Au25@UiO-66.Notably,the sandwich-like nanocomposite displays significantly enhanced catalytic activity along with an excellent stability when used in the selective photocatalytic aerobic oxidation of sulfide to sulfoxide.As comparison,AU25 NCs simply located at the outer surface or insider matrix of UiO-66(short as Au2/UiO-66 and AU2s@UiO-66)show poor stability and low conversion,respectively.This structure regulated difference in the catalytic performances of three nanocomposites is assigned to the varied distribution of active sites(Au NCs)in metal-organic frameworks(MOFs).This work offers the opportunity for application of nanoclusters in catalysis,energy conversion and even biology.展开更多
Fluorescent metal nanoclusters（MNCs） have recently emerged as a novel kind of promising fluorescent probes for biological imaging because of their ultrasmall core size（〈2 nm）, strong photoluminescence,facile avai...Fluorescent metal nanoclusters（MNCs） have recently emerged as a novel kind of promising fluorescent probes for biological imaging because of their ultrasmall core size（〈2 nm）, strong photoluminescence,facile availability and good biocompatibility. In this review, we provide an update on recent advances in the development of near infrared（NIR）-emitting MNCs in terms of synthesis strategies and bioimaging applications. We mainly focus on the utilization of NIR-emitting MNCs（including Au, Ag, Cu and alloy NCs） either as single modal imaging（fluorescence intensity-based imaging, fluorescence lifetime imaging, two-photon imaging） probes or as multimodal imaging（such as NIR fluorescence/X-ray computed tomography/magnetic resonance imaging, NIR fluorescence/photoacoustic imaging/magnetic resonance imaging, NIR fluorescence/single photon emission computed tomography） probes in biological cells and tissues. Finally, we give a brief outlook on the future challenges and prospects of developing NIR-emitting MNCs for bioimaging.展开更多
The present work reports a sensitive and selective fluorescent sensor for the detection of mercury ion, Hg（II）, by hybridizing carbon nanodots （C-dots） and gold nanoclusters （Au NCs） through intrinsic interactio...The present work reports a sensitive and selective fluorescent sensor for the detection of mercury ion, Hg（II）, by hybridizing carbon nanodots （C-dots） and gold nanoclusters （Au NCs） through intrinsic interactions of the two components. The C-dots serve as the reference signal and the Au NCs as the reporter. This method employs the specific high affinity metallophilic Hg2^-Au＋ interactions which can greatly quench the red fluorescence of Au NCs, while the blue fluorescence of C-dots is stable against Hg（II）, leading to distinct ratiometric fluorescence changes when exposed to Hg（II）. A limit of detection of 28 nM for Hg（II） in aqueous solution was estimated. Thus we applied the sensor for the detection of Hg（II） in real water samples including tap water, lake water and mineral water samples with good results. We further demonstrated that a visual chemical sensor could be manufactured by immobilizing the nanohybrid probe on a cellulose acetate circular filter paper. The paper-based sensor immediately showed a distinct fluorescence color evolution from pink to blue after exposure to a drop of the Hg（II） solution展开更多
Gold（Au） nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first tim...Gold（Au） nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first time the support shape effect on the catalysis of Au nanoclusters by using CO oxidation as a model reaction. Au22（L8）6（L = 1,8-bis（diphenylphosphino） octane） nanoclusters were supported on CeO2 rods or cubes, then pretreated at different temperatures（up to 673 K）, allowing the gradual removal of the organic phosphine ligands. CO oxidation test over these differently pretreated samples shows that CeO2 rods are much better supports than cubes for Au22 nanoclusters in enhancing the reaction rate. In situ IR spectroscopy coupled with CO adsorption indicates that the shape of CeO2 support can impact the nature and quantity of exposed Au sites, as well as the efficiency of organic ligand removal. Although CeO2 rods are helpful in exposing a greater percentage of total Au sites upon ligands removal, the percentage of active Au sites（denoted by Au d＋, 0 〈 d 〈 1） is lower than that on CeO2 cubes. The in situ extended X-ray absorption spectroscopy（EXAFS） and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM） results show that the Au nanoclusters bound more strongly to the CeO2 rods than to the cubes where the Au nanoclusters show more sintering. Considering the typical redox mechanism for CO oxidation over supported Au nanoclusters and nanoparticles, it is concluded that the reactivity of the lattice oxygen of CeO2 is the determining factor for CO oxidation over Au22/CeO2. CeO2 rods offer more reactive lattice oxygen and abundant oxygen vacancies than the cubes and thus make the rods a superior support for Au nanoclusters in catalyzing low temperature CO oxidation.展开更多
Biotemplated metal nanoclusters have garnered much attention owing to their wide range of potential applications in biosensing, bioimaging, catalysis, and nanomedicine. Here, we report the synthesis of stable, biocomp...Biotemplated metal nanoclusters have garnered much attention owing to their wide range of potential applications in biosensing, bioimaging, catalysis, and nanomedicine. Here, we report the synthesis of stable, biocompatible, watersoluble, and highly fluorescent bovine serum albumin-templated cadmium nanoclusters （CdNcs） through a facile one-pot green method. We covalently conjugated hyaluronic acid （HA） to the CdNcs to form a pH-responsive, tumor- targeting theranostic nanocarrier with a sustained release profile for doxorubicin （DOX）, a model anticancer drug. The nanocarrier showed a DOX encapsulation efficiency of about 75.6%. DOX release profiles revealed that 74% of DOX was released at pH 5.3, while less than 26% of DOX was released at pH 7.4 within the same 24-h period. The nanocarrier selectively recognized MCF-7 breast cancer cells expressing CD44, a cell surface receptor for HA, whereas no such recognition was observed with HA receptor-negative HEK293 cells. Biocompatibility of the nanocarrier was evaluated through cytotoxicity assays with HEK293 and MCF-7 ceils. The nanocarrier exhibited very low to no cytotoxicity, whereas the DOX-loaded nanocarrier showed considerable cellular uptake and enhanced MCF-7 breast cancer cell-killing ability. We also confirmed the feasibility of using the highly fluorescent nanoconjugate for bioimaging of MCF-7 and HeLa cells. The superior targeted drug delivery efficacy, cellular imaging capability, and low cytotoxicity position this nanoconjugate as an exciting new nanoplatform with promising biomedical applications.展开更多
In general, copper nanoclusters (CuNCs) possess very low or even virtually no bactericidal effect. Herein,we report a novel CuNCs possessing significantly high antibacterial activity, that is tannic acid (TA)capped Cu...In general, copper nanoclusters (CuNCs) possess very low or even virtually no bactericidal effect. Herein,we report a novel CuNCs possessing significantly high antibacterial activity, that is tannic acid (TA)capped CuNCs (TA-CuNCs). TA-CuNCs exhibit strong absorption and excitation-dependent fluorescence within pH 2-12, resulting from the functional groups of TA-CuNCs due to two prototropic equilibria,phenolphenolate and carboxyliccarboxylate. There exists synergistic effect of TA and copper nanoclusters which endows TA-CuNCs remarkable antibacterial capability as a microbicide, as characterized by the effective inhibition on the growth of gram-positive bacteria by damaging the cell membrane. By incubating 1 x 10~7 CFU/mL of gram-positive bacteria Staphylococcus aureus and Bacillus subtilis with 30 μg/mL of TA-CuNCs for 10 min, the bacteria are completely inhibited, while under same conditions the viabilities of gram-negative bacteria Escherichia coli 0157:H7 and Pseudomonas aeruginosa remain 85.0%, 72.0%, respectively. In addition, TA-CuNCs exhibit low cytotoxicity and favorable biocompatibility demonstrated by standard methyl thiazolyl tetrazolium (MTT) assay with HepG2 and 293 Tcells, giving rise to cell viability of 94.2% for HepG2 and 96.7% for 293 T by incubating 10~6 cell/mL with 200 μg/mL of TA-CuNCs for 24 h. These results make TA-CuNCs a potential alternative as bactericide for infection treatment caused by gram-positive bacteria.展开更多
Gold nanoclusters(AuNCs)are an emerging type of ultrasmall nanomaterials possessing unique physicochemical characteristics.Metal–organic frameworks(MOFs),a singular kind of porous solid and crystalline material,have ...Gold nanoclusters(AuNCs)are an emerging type of ultrasmall nanomaterials possessing unique physicochemical characteristics.Metal–organic frameworks(MOFs),a singular kind of porous solid and crystalline material,have attracted tremendous attention in recent years.The combination of AuNCs and MOFs can integrate and improve the prominent properties of both components,such as high catalytic activities,tunable optical properties,good biocompatibility,surface functionality and stability,which make the composites of MOFs and AuNCs promising for sensing applications.This review systematically summarizes the recent progress on the sensing of various analytes via MOFs-mediated AuNCs assemblies based on strategies of luminescence sensing,colorimetric sensing,electrochemiluminescence sensing,and electrochemical and photoelectrochemical sensing.A brief outlook regarding the future development of MOFs-mediated AuNCs assemblies for sensing application is presented as well.展开更多
Plasma fibrinogen(F1)and fibronectin(pFN)polymerize to form a fibrin clot that is both a hemostatic and provisional matrix for wound healing.About 90%of plasma F1 has a homodimeric pair ofγchains(γγF1),and 10%has a...Plasma fibrinogen(F1)and fibronectin(pFN)polymerize to form a fibrin clot that is both a hemostatic and provisional matrix for wound healing.About 90%of plasma F1 has a homodimeric pair ofγchains(γγF1),and 10%has a heterodimeric pair ofγand more acidicγ′chains(γγ′F1).We have synthesized a novel fibrin matrix exclusively from a 1:1(molar ratio)complex ofγγ′F1 and pFN in the presence of highly active thrombin and recombinant Factor XIII(rFXIIIa).In this matrix,the fibrin nanofibers were decorated with pFN nanoclusters(termedγγ′F1:pFN fibrin).In contrast,fibrin made from 1:1 mixture ofγγF1 and pFN formed a sporadic distribution of“pFN droplets”(termedγγF1+pFN fibrin).Theγγ′F1:pFN fibrin enhanced the adhesion of primary human umbilical vein endothelium cells(HUVECs)relative to theγγF1+FN fibrin.Three dimensional(3D)culturing showed that theγγ′F1:pFN complex fibrin matrix enhanced the proliferation of both HUVECs and primary human fibroblasts.HUVECs in the 3Dγγ′F1:pFN fibrin exhibited a starkly enhanced vascular morphogenesis while an apoptotic growth profile was observed in theγγF1+pFN fibrin.Relative toγγF1+pFN fibrin,mouse dermal wounds that were sealed byγγ′F1:pFN fibrin exhibited accelerated and enhanced healing.This study suggests that a 3D pFN presentation on a fibrin matrix promotes wound healing.展开更多
Thiolate(SR)-protected gold nanoclusters(Aun(SR)m NCs)are a rare type of material capable of simultaneously exhibiting multiple physicochemical properties well-suited to specific applications,including photoluminescen...Thiolate(SR)-protected gold nanoclusters(Aun(SR)m NCs)are a rare type of material capable of simultaneously exhibiting multiple physicochemical properties well-suited to specific applications,including photoluminescence,thermocatalysis,electrocatalysis,photocatalysis,magnetism,and optical activity.Over the past several decades,there has been tremendous progress in our understanding of the structure and physicochemical properties of Aun(SR)m NCs,resulting in the ability to fine-tune the characteristics of these materials.It is therefore helpful to examine the extent to which the properties of Aun(SR)m and related metal NCs can now be adjusted based on design.This review presents representative examples of previous studies concerning the geometry,electronic structure,luminescence properties,catalysis,magnetism and optical activity of Aun(SR)m and related metal NCs and discusses the current status of the designability of these NCs to impart specific structural and physicochemical characteristics.This information is expected to accelerate the fabrication of highly functional materials based on Aun(SR)m and related metal NCs.展开更多
Heteroatom dopants can greatly modify the electronic and physical properties and catalytic performance of gold nanoclusters. In this study, we investigate the catalytic activity of [Au25-x（PET）18-xM]NH3 （PET = 2-ph...Heteroatom dopants can greatly modify the electronic and physical properties and catalytic performance of gold nanoclusters. In this study, we investigate the catalytic activity of [Au25-x（PET）18-xM]NH3 （PET = 2-phenylethanethiolate, and M = Cu, Co, Ni, and Zn） nanoclusters in aerobic alcohol oxidation. The [Au25-xPET）18-xM]NH3 nanoclusters are thoroughly characterized by matrix assisted laser desorption ionization （MALDI） mass spectrometry, X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectroscopy （FT-IR）, and inductively coupled plasma-mass spectrometry （ICP-MS）. The XPS analyses suggest that the transition metals strongly interact with the gold atoms of the nanoclusters. The CeO2-supported nanoclusters show catalytic activity, based on the conversion of benzyl alcohol, in the order, [Au25-x（PET）18-xNi] 〉 [Au25-x（PET）18-xCu] 〉 [Au25-x（PET）18-xZn] 〉 [Au25-x（PET）18-xCo]. Regarding product selectivity, the [Au25-xPET）18-xZn] and [Au25-x（PET）18-xCo] catalysts preferably yield benzaldehyde, [Au25-x（PET）18-xCu] yields benzaldehyde and benzyl acid, and [Au25-x（PET）18-xNi] yields benzyl acid. The exposed metal atoms are considered as the catalytic active sites. Also, the catalytic performance （including activity and selectivity） of the [Au25-x（PET）18-xM] catalysts is greatly turned and mediated by the transition metal type.展开更多
The electrochemical carbon dioxide reduction reaction(eCO_(2)RR),which converts CO_(2)into various hydrocarbons or alcohols,has been extensively researched because it promises a sustainable energy economy.However,only...The electrochemical carbon dioxide reduction reaction(eCO_(2)RR),which converts CO_(2)into various hydrocarbons or alcohols,has been extensively researched because it promises a sustainable energy economy.However,only copper(Cu)can currently achieve stable and efficient hydrocarbon conversion in the eCO_(2)RR.Therefore,understanding the catalytic mechanisms and summarizing the research progress on synthesis strategies of Cu catalysts are essential for the eCO_(2)RR.This paper reviews Cu catalysts with different surface states of Cu catalysts:oxide-derived Cu,Cu nanoparticles,Cu single atoms,and Cu nanoclusters.It then reviews the development and progress of different Cu-catalyst preparation methods in recent years,focusing on the activity and selectivity of materials.Besides revealing the tendencies of catalytic selection and deep reactive mechanisms of Cu catalysts with four different surface states,this review can guide the subsequent construction of catalysts and provides an understanding of catalytic mechanisms.展开更多
Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge ...Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge carriers of conventional photocatalysts strongly limited their photocatalytic H_(2)O_(2) generation performance.Herein,we design a highly efficient photocatalyst in this work by marrying luminescent gold-silver nanoclusters(AuAg NCs)to polyethyleneimine(PEI)modified C_(3)N_(4)(C3N4-PEI).The key design in this work is the utilization of highly luminescent AuAg NCs as photosensitizers to promote the generation and separation of charge carriers of C_(3)N_(4)-PEI,thereby ultimately producing abundant e−for O_(2) reduction under visible light illumination(λ≥400 nm).As a result,the as-designed photocatalyst(C3N4-PEI-AuAg NCs)exhibits excellent photocatalytic activity with an H_(2)O_(2) production capability of 82μM in pure water,which is 3.5 times higher than pristine C_(3)N_(4)(23μM).This interesting design provides a paradigm in developing other high-efficient photocatalysts for visible-light-driven H_(2)O_(2) production.展开更多
基金This research was supported by the National Key Research and development Program of China （No. 2016YFA0202701）, the Program of Introducing Talents of Discipline to Universities （No. B14003）, the National Natural Science Foundation of China （NSFC） （Nos. 51722203, 21771024, 51672026 and 51527802）, the Research Fund of Co-construction Program from Beijing Municipal Commission of Education （No. Z161100002116027）, and the Fundamental Research Funds for the Central Universities.
文摘Magnetic metals （Fe, Co, Ni） and alloys thereof are easily synthesized as nanoparticles, but obtaining highly dispersed graphene-based magnetic nanomaterials remains challenging. Here, three CoNi/graphene nanocomposites （CoNi/GN） are successfully assembled for the first time via a one-pot strategy without templating by manipulating the reaction time and solvents used for the same precursors. Moreover, the reduction of graphene oxide utilizing this method is more effective than that by conventional methods and the alloy particles are firmly embedded on the GN substrate. Compared to n- and p-CoNi/GN nanocomposites, o-CoNi/GN nanocomposites show the best electromagnetic wave absorption properties with the maximum reflection loss of -31.0 dB at 4.9 GHz for a thickness of 4 mm; the effective absorption bandwidth （〈 10.0 dB） is 7.3 GHz （9.5-16.8 GHz） for a thickness of 2 mm. The structures and electromagnetic wave absorption mechanisms of the three composites were also investigated. This research provides a new platform for the development of magnetic alloy nanoparticles in the field of microwave-absorbing devices.
文摘Metallic silver （Ag） and its ability to combat infection have been known since ancient history. In the wake of nanotechnology advancement, silver＇s efficacy to fight broad spectrum bacterial infections is further improved in the form of Ag nanoparticles （NPs）. Recent studies have ascribed the broad spectrum antimicrobial properties of Ag NPs to dissociation of Ag＊ ions from the NPs, which may not be entirely applicable when the size of Ag NPs decreases to the sub-2 nm range [denoted Ag nanoclusters （NCs）]. In this paper we report that ultrasmall glutathione （GSH）-protected Ag^＋-rich NCs （Ag^＋-R NCs for short, with a predominance of Ag＋ species in the NCs） have much higher antimicrobial activities towards both gram-negative and gram-positive bacteria than the reference NC, GSH-Ag^＋-R NCs. They have the same size and surface ligand, but with different oxidation states of the core silver. This interesting finding suggests that the undissociated Ag^＋-R NCs armed with abundant Ag^＋ ions on the surface are highly active in bacterial killing, which was not observed in the system of their larger counterpart, Ag NPs.
基金support of the National Natural Science Foundation of China (Nos. 21375017, 21105012 and 21205015)the National Science Foundation for Distinguished Young Scholars of Fujian Province (No. 2013J06003)+3 种基金the Key Project of Fujian Science and Technology (No. 2013Y0045)the Program for New Century Excellent Talents of Colleges and Universities in Fujian Province (Nos. JA13130 and JA13088)the Program for Fujian University Outstanding Youth Scientific Research (Nos. JA11105 and JA10295)the Foundation of Fuzhou Science and Technology Bureau (No. 2013-S-122-4)
文摘In this paper, the DNA-templated Ag/Pt bimetallic nanoclusters were successfully synthesized using an optimized synthetic scheme. The obtained DNA-Ag/Pt NCs have an ultrasmall particle size and excellent distribution. The DNA-Ag/Pt NCs show intrinsic peroxidase-mimicking activity and can effectively catalyze the H2O2-mediated oxidation of a substrate, 3,30,5,50-tetramethylbenzidine（TMB）, to produce a blue colored product. Based on this specific property, we employed the aptamer of VEGF to design a label-free electrochemical biosensor for VEGF detection. Under the optimized experimental conditions, a linear range from 6.0 pmol/L to 20 pmol/L was obtained with a detection limit of 4.6 pmol/L. The proposed biosensor demonstrated its high specificity for VEGF and could directly detect the VEGF concentration in human serum samples of breast cancer patients with satisfactory results. This novel electrochemical aptasensor was simple and convenient to use and was cost-effective and label-free in design, and would hold potential applications in medical diagnosis and treatment.
基金The authors acknowledge funding from the National Key Research and Development Program of China(No.2018YFB1502400)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA21090400)the Jilin Province Science and Technology Development Program(Nos.20190201300JC and 20180101030JC).
文摘Single atom catalysts(SACs)were reported to demonstrate exciting catalytic features for a number of reactions,including hydrogen evolution reaction(HER).However,the true role of these single atom sites in catalysts remains elusive,particularly for those prepared via pyrolysis,where the formation of active nanoparticle counterparts is often unavoidable.Here we report a Ru based catalyst(Ru embedded in N doped carbon spheres(Ru/NPCS))comprising of both Ru nanoclusters and Ru single sites,who demonstrates activity exceeding Pt catalyst and mass activity among the best of the Ru based catalysts under acidic conditions.The integration of proton exchange membrane water electrolysis with Ru/NPCS as a cathode exhibited an excellent hydrogen generation activity and extraordinary stability(during 120 h of electrolysis)with a 1/48 Ru loading(16.5μgRu·cm^(−2))of a commercial 20%Pt/C catalyst.Through precisely tailoring the dispersion status of the catalysts,we reveal that while ruthenium nanoclusters actively catalyze HER via Volmer–Tafel mechanism,the Ru SACs barely catalyze HER,with H*adsorption difficult to occur.Moreover,no synergy between Ru SACs and Ru cluster is revealed,meaning the Ru SACs act as a spectator rather than active species during H2 evolution.
基金the National Key Basic Research Program of China(No.2016YFA0200700,Z.Y.T)the National Natural Science Foundation of China(Nos.21890381 and 21721002,Z.Y.T)+1 种基金Frontier Science Key Project of Chinese Academy of Sciences(No.QYZDJ-SSW-SLH038,Z.Y.T)K.C.Wong Education Foundation(Z.Y.T).
文摘Atomically precise gold(Au)nanoclusters(NCs)as visible light photosensitizers supported on the substrate for photoredox catalysis have attracted considerable attentions.However,eficient control of their photocatalytic activity and long-term stability is still challenging.Herein,we report a coordination-assisted self-assembly strategy in combination with electrostatic interaction to sandwich Au2:(Capt)18(abbreviated as AU25,Capt=captopril)NCs between an inner core and an outer shell made of UiO-66,denoted as UiO-66@Au25@UiO-66.Notably,the sandwich-like nanocomposite displays significantly enhanced catalytic activity along with an excellent stability when used in the selective photocatalytic aerobic oxidation of sulfide to sulfoxide.As comparison,AU25 NCs simply located at the outer surface or insider matrix of UiO-66(short as Au2/UiO-66 and AU2s@UiO-66)show poor stability and low conversion,respectively.This structure regulated difference in the catalytic performances of three nanocomposites is assigned to the varied distribution of active sites(Au NCs)in metal-organic frameworks(MOFs).This work offers the opportunity for application of nanoclusters in catalysis,energy conversion and even biology.
基金Financial supports from the National 1000 Young Talent ProgramNational Natural Science Foundation of China (NSFC, No. 21705129)Program of Introducing Talents of Discipline to Universities (No. B08040)
文摘Fluorescent metal nanoclusters（MNCs） have recently emerged as a novel kind of promising fluorescent probes for biological imaging because of their ultrasmall core size（〈2 nm）, strong photoluminescence,facile availability and good biocompatibility. In this review, we provide an update on recent advances in the development of near infrared（NIR）-emitting MNCs in terms of synthesis strategies and bioimaging applications. We mainly focus on the utilization of NIR-emitting MNCs（including Au, Ag, Cu and alloy NCs） either as single modal imaging（fluorescence intensity-based imaging, fluorescence lifetime imaging, two-photon imaging） probes or as multimodal imaging（such as NIR fluorescence/X-ray computed tomography/magnetic resonance imaging, NIR fluorescence/photoacoustic imaging/magnetic resonance imaging, NIR fluorescence/single photon emission computed tomography） probes in biological cells and tissues. Finally, we give a brief outlook on the future challenges and prospects of developing NIR-emitting MNCs for bioimaging.
文摘The present work reports a sensitive and selective fluorescent sensor for the detection of mercury ion, Hg（II）, by hybridizing carbon nanodots （C-dots） and gold nanoclusters （Au NCs） through intrinsic interactions of the two components. The C-dots serve as the reference signal and the Au NCs as the reporter. This method employs the specific high affinity metallophilic Hg2^-Au＋ interactions which can greatly quench the red fluorescence of Au NCs, while the blue fluorescence of C-dots is stable against Hg（II）, leading to distinct ratiometric fluorescence changes when exposed to Hg（II）. A limit of detection of 28 nM for Hg（II） in aqueous solution was estimated. Thus we applied the sensor for the detection of Hg（II） in real water samples including tap water, lake water and mineral water samples with good results. We further demonstrated that a visual chemical sensor could be manufactured by immobilizing the nanohybrid probe on a cellulose acetate circular filter paper. The paper-based sensor immediately showed a distinct fluorescence color evolution from pink to blue after exposure to a drop of the Hg（II） solution
基金supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Divisionsupported by the U.S. Department of Energy, Office of Science, Office of Basic Energy, Sciences under Contract No. DE-AC02-76SF00515the facilities support at the beamline BL 2-2 provided by the Synchrotron Catalysis Consortium U.S. DOE (No. De-SC0012335)
文摘Gold（Au） nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first time the support shape effect on the catalysis of Au nanoclusters by using CO oxidation as a model reaction. Au22（L8）6（L = 1,8-bis（diphenylphosphino） octane） nanoclusters were supported on CeO2 rods or cubes, then pretreated at different temperatures（up to 673 K）, allowing the gradual removal of the organic phosphine ligands. CO oxidation test over these differently pretreated samples shows that CeO2 rods are much better supports than cubes for Au22 nanoclusters in enhancing the reaction rate. In situ IR spectroscopy coupled with CO adsorption indicates that the shape of CeO2 support can impact the nature and quantity of exposed Au sites, as well as the efficiency of organic ligand removal. Although CeO2 rods are helpful in exposing a greater percentage of total Au sites upon ligands removal, the percentage of active Au sites（denoted by Au d＋, 0 〈 d 〈 1） is lower than that on CeO2 cubes. The in situ extended X-ray absorption spectroscopy（EXAFS） and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM） results show that the Au nanoclusters bound more strongly to the CeO2 rods than to the cubes where the Au nanoclusters show more sintering. Considering the typical redox mechanism for CO oxidation over supported Au nanoclusters and nanoparticles, it is concluded that the reactivity of the lattice oxygen of CeO2 is the determining factor for CO oxidation over Au22/CeO2. CeO2 rods offer more reactive lattice oxygen and abundant oxygen vacancies than the cubes and thus make the rods a superior support for Au nanoclusters in catalyzing low temperature CO oxidation.
文摘Biotemplated metal nanoclusters have garnered much attention owing to their wide range of potential applications in biosensing, bioimaging, catalysis, and nanomedicine. Here, we report the synthesis of stable, biocompatible, watersoluble, and highly fluorescent bovine serum albumin-templated cadmium nanoclusters （CdNcs） through a facile one-pot green method. We covalently conjugated hyaluronic acid （HA） to the CdNcs to form a pH-responsive, tumor- targeting theranostic nanocarrier with a sustained release profile for doxorubicin （DOX）, a model anticancer drug. The nanocarrier showed a DOX encapsulation efficiency of about 75.6%. DOX release profiles revealed that 74% of DOX was released at pH 5.3, while less than 26% of DOX was released at pH 7.4 within the same 24-h period. The nanocarrier selectively recognized MCF-7 breast cancer cells expressing CD44, a cell surface receptor for HA, whereas no such recognition was observed with HA receptor-negative HEK293 cells. Biocompatibility of the nanocarrier was evaluated through cytotoxicity assays with HEK293 and MCF-7 ceils. The nanocarrier exhibited very low to no cytotoxicity, whereas the DOX-loaded nanocarrier showed considerable cellular uptake and enhanced MCF-7 breast cancer cell-killing ability. We also confirmed the feasibility of using the highly fluorescent nanoconjugate for bioimaging of MCF-7 and HeLa cells. The superior targeted drug delivery efficacy, cellular imaging capability, and low cytotoxicity position this nanoconjugate as an exciting new nanoplatform with promising biomedical applications.
基金financially supported by the National Natural Science Foundation of China(Nos.21675019,21727811,21575020)Fundamental Research Funds for the Central Universities (Nos. N170505002,N170504017,N170507001)
文摘In general, copper nanoclusters (CuNCs) possess very low or even virtually no bactericidal effect. Herein,we report a novel CuNCs possessing significantly high antibacterial activity, that is tannic acid (TA)capped CuNCs (TA-CuNCs). TA-CuNCs exhibit strong absorption and excitation-dependent fluorescence within pH 2-12, resulting from the functional groups of TA-CuNCs due to two prototropic equilibria,phenolphenolate and carboxyliccarboxylate. There exists synergistic effect of TA and copper nanoclusters which endows TA-CuNCs remarkable antibacterial capability as a microbicide, as characterized by the effective inhibition on the growth of gram-positive bacteria by damaging the cell membrane. By incubating 1 x 10~7 CFU/mL of gram-positive bacteria Staphylococcus aureus and Bacillus subtilis with 30 μg/mL of TA-CuNCs for 10 min, the bacteria are completely inhibited, while under same conditions the viabilities of gram-negative bacteria Escherichia coli 0157:H7 and Pseudomonas aeruginosa remain 85.0%, 72.0%, respectively. In addition, TA-CuNCs exhibit low cytotoxicity and favorable biocompatibility demonstrated by standard methyl thiazolyl tetrazolium (MTT) assay with HepG2 and 293 Tcells, giving rise to cell viability of 94.2% for HepG2 and 96.7% for 293 T by incubating 10~6 cell/mL with 200 μg/mL of TA-CuNCs for 24 h. These results make TA-CuNCs a potential alternative as bactericide for infection treatment caused by gram-positive bacteria.
基金supported by the Natural Science Foundation of Chongqing(cstc2020jcyj-msxmX1053)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(2020-QZ-01)
文摘Gold nanoclusters(AuNCs)are an emerging type of ultrasmall nanomaterials possessing unique physicochemical characteristics.Metal–organic frameworks(MOFs),a singular kind of porous solid and crystalline material,have attracted tremendous attention in recent years.The combination of AuNCs and MOFs can integrate and improve the prominent properties of both components,such as high catalytic activities,tunable optical properties,good biocompatibility,surface functionality and stability,which make the composites of MOFs and AuNCs promising for sensing applications.This review systematically summarizes the recent progress on the sensing of various analytes via MOFs-mediated AuNCs assemblies based on strategies of luminescence sensing,colorimetric sensing,electrochemiluminescence sensing,and electrochemical and photoelectrochemical sensing.A brief outlook regarding the future development of MOFs-mediated AuNCs assemblies for sensing application is presented as well.
基金supported by the University of Nebraska Research Initiative 2018–2019(YL and WV)the University of Nebraska-Lincoln start-up(YL)+3 种基金the Nebraska DHHS Stem Cell Grant 2019(YL and WV)the U.S.Army GRANT10824516(WV)the Department of Defense,USA,W81XWH-BAA-11-1(WV)This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior–Brasil(CAPES)–Finance Code 88882.434714/2019–01(EPA and LAV)。
文摘Plasma fibrinogen(F1)and fibronectin(pFN)polymerize to form a fibrin clot that is both a hemostatic and provisional matrix for wound healing.About 90%of plasma F1 has a homodimeric pair ofγchains(γγF1),and 10%has a heterodimeric pair ofγand more acidicγ′chains(γγ′F1).We have synthesized a novel fibrin matrix exclusively from a 1:1(molar ratio)complex ofγγ′F1 and pFN in the presence of highly active thrombin and recombinant Factor XIII(rFXIIIa).In this matrix,the fibrin nanofibers were decorated with pFN nanoclusters(termedγγ′F1:pFN fibrin).In contrast,fibrin made from 1:1 mixture ofγγF1 and pFN formed a sporadic distribution of“pFN droplets”(termedγγF1+pFN fibrin).Theγγ′F1:pFN fibrin enhanced the adhesion of primary human umbilical vein endothelium cells(HUVECs)relative to theγγF1+FN fibrin.Three dimensional(3D)culturing showed that theγγ′F1:pFN complex fibrin matrix enhanced the proliferation of both HUVECs and primary human fibroblasts.HUVECs in the 3Dγγ′F1:pFN fibrin exhibited a starkly enhanced vascular morphogenesis while an apoptotic growth profile was observed in theγγF1+pFN fibrin.Relative toγγF1+pFN fibrin,mouse dermal wounds that were sealed byγγ′F1:pFN fibrin exhibited accelerated and enhanced healing.This study suggests that a 3D pFN presentation on a fibrin matrix promotes wound healing.
基金Japan Society for the Promotion of Science,Grant/Award Numbers:20H02698,20H02552,18H05178,20H05115Hydrogenomics,Grant/Award Number:21H00027+7 种基金Aquatic Functional Materials,Grant/Award Numbers:18H05178,22H04562Yazaki Memorial Foundation for Science and TechnologyOgasawara Foundation for the Promotion of Science and EngineeringKao Foundation for Arts and SciencesTEPCO Memorial FoundationJapan Science SocietyTakahashi Industrial and Economic Research FoundationKubota Corporation。
文摘Thiolate(SR)-protected gold nanoclusters(Aun(SR)m NCs)are a rare type of material capable of simultaneously exhibiting multiple physicochemical properties well-suited to specific applications,including photoluminescence,thermocatalysis,electrocatalysis,photocatalysis,magnetism,and optical activity.Over the past several decades,there has been tremendous progress in our understanding of the structure and physicochemical properties of Aun(SR)m NCs,resulting in the ability to fine-tune the characteristics of these materials.It is therefore helpful to examine the extent to which the properties of Aun(SR)m and related metal NCs can now be adjusted based on design.This review presents representative examples of previous studies concerning the geometry,electronic structure,luminescence properties,catalysis,magnetism and optical activity of Aun(SR)m and related metal NCs and discusses the current status of the designability of these NCs to impart specific structural and physicochemical characteristics.This information is expected to accelerate the fabrication of highly functional materials based on Aun(SR)m and related metal NCs.
文摘Heteroatom dopants can greatly modify the electronic and physical properties and catalytic performance of gold nanoclusters. In this study, we investigate the catalytic activity of [Au25-x（PET）18-xM]NH3 （PET = 2-phenylethanethiolate, and M = Cu, Co, Ni, and Zn） nanoclusters in aerobic alcohol oxidation. The [Au25-xPET）18-xM]NH3 nanoclusters are thoroughly characterized by matrix assisted laser desorption ionization （MALDI） mass spectrometry, X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectroscopy （FT-IR）, and inductively coupled plasma-mass spectrometry （ICP-MS）. The XPS analyses suggest that the transition metals strongly interact with the gold atoms of the nanoclusters. The CeO2-supported nanoclusters show catalytic activity, based on the conversion of benzyl alcohol, in the order, [Au25-x（PET）18-xNi] 〉 [Au25-x（PET）18-xCu] 〉 [Au25-x（PET）18-xZn] 〉 [Au25-x（PET）18-xCo]. Regarding product selectivity, the [Au25-xPET）18-xZn] and [Au25-x（PET）18-xCo] catalysts preferably yield benzaldehyde, [Au25-x（PET）18-xCu] yields benzaldehyde and benzyl acid, and [Au25-x（PET）18-xNi] yields benzyl acid. The exposed metal atoms are considered as the catalytic active sites. Also, the catalytic performance （including activity and selectivity） of the [Au25-x（PET）18-xM] catalysts is greatly turned and mediated by the transition metal type.
基金supported by the Tianjin Science and Technology support key projects (20JCYBJC01420)。
文摘The electrochemical carbon dioxide reduction reaction(eCO_(2)RR),which converts CO_(2)into various hydrocarbons or alcohols,has been extensively researched because it promises a sustainable energy economy.However,only copper(Cu)can currently achieve stable and efficient hydrocarbon conversion in the eCO_(2)RR.Therefore,understanding the catalytic mechanisms and summarizing the research progress on synthesis strategies of Cu catalysts are essential for the eCO_(2)RR.This paper reviews Cu catalysts with different surface states of Cu catalysts:oxide-derived Cu,Cu nanoparticles,Cu single atoms,and Cu nanoclusters.It then reviews the development and progress of different Cu-catalyst preparation methods in recent years,focusing on the activity and selectivity of materials.Besides revealing the tendencies of catalytic selection and deep reactive mechanisms of Cu catalysts with four different surface states,this review can guide the subsequent construction of catalysts and provides an understanding of catalytic mechanisms.
基金National Natural Science Foundation of China(21908121,22071127)Taishan Scholar Foundation(tsqn201812074,China)Scientific Research Foundation of Qingdao University of Science and Technology(210/010029031,and 210/010029008).
文摘Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge carriers of conventional photocatalysts strongly limited their photocatalytic H_(2)O_(2) generation performance.Herein,we design a highly efficient photocatalyst in this work by marrying luminescent gold-silver nanoclusters(AuAg NCs)to polyethyleneimine(PEI)modified C_(3)N_(4)(C3N4-PEI).The key design in this work is the utilization of highly luminescent AuAg NCs as photosensitizers to promote the generation and separation of charge carriers of C_(3)N_(4)-PEI,thereby ultimately producing abundant e−for O_(2) reduction under visible light illumination(λ≥400 nm).As a result,the as-designed photocatalyst(C3N4-PEI-AuAg NCs)exhibits excellent photocatalytic activity with an H_(2)O_(2) production capability of 82μM in pure water,which is 3.5 times higher than pristine C_(3)N_(4)(23μM).This interesting design provides a paradigm in developing other high-efficient photocatalysts for visible-light-driven H_(2)O_(2) production.
