L10-FePt nan oparticles(NPs)with high chemical ordering represent effective electrocatalysts to reduce the cost and enhance theircatalytic performanee in fuel cells.A molecular strategy of preparing highly ordered FeP...L10-FePt nan oparticles(NPs)with high chemical ordering represent effective electrocatalysts to reduce the cost and enhance theircatalytic performanee in fuel cells.A molecular strategy of preparing highly ordered FePt NPs was used by direct pyrolysis of a Fe,Pt-containing bimetallic complex.The resultant L10-FePt NPs had very high crystallinity as reflected by the obvious diffractionpatterns,clear lattice fringes and characteristic X-ray diffraction peaks,etc.Besides,the strong ferromagnetism with room temperaturecoercivity of 27 kOe further confirmed the face-centered tetrag on al(fet)phase in good agreement with the ordered nano structures.TheFePt NPs can be used as electrocatalysts to catalyze oxygen reduction reaction(ORR)in an O2·saturated 0.1 M HClO4 solution andhydrogen evolution reaction(HER)in the 0.5 M H2SO4 electrolyte with much better performance than commercial Pt/C,and showedquite high stability after 10,000 cycles.The strategy utilizing orga no metallic precursors to prepare metal alloy NPs was dem on strated tobe a reliable approach for improving the catalytic efficiency in fuel cells.展开更多
Modulating electronic structures of single-atom metal cocatalysts is vital for highly active photoreduction of CO_(2),and it's especially challenging to develop a facile method to modify the dispersion of atomical...Modulating electronic structures of single-atom metal cocatalysts is vital for highly active photoreduction of CO_(2),and it's especially challenging to develop a facile method to modify the dispersion of atomical photocatalytic sites.We herein report an ion-loading pyrolysis route to in-situ anchor Pd single atoms as well as twinned Pd nanoparticles on ultra-thin graphitic carbon nitride nanosheets(PdTP/Pd_(SA)-CN)for high-efficiency photoreduction of CO_(2).The anchored Pd twinned nanoparticles donate electrons to adjacent single Pd–N_(4) sites through the carbon nitride networks,and the optimized PdTP/Pd_(SA)-CN photocatalyst exhibits a CO evolution rate up to 46.5μmol g^(-1) h^(-1) with nearly 100%selectivity.As revealed by spectroscopic and theoretical analyses,the superior photocatalytic activity is attributed to the lowered desorption barrier of carbonyl species at electron-enriched Pd single atoms,together with the improved efficiencies of light-harvesting and charge separation/transport.This work has demonstrated the engineering of the electron density of single active sites with twinned metal nanoparticles assisted by strong electronic interaction with the support of the atomic metal,and unveiled the underlying mechanism for expedited photocatalytic efficiency.展开更多
Sensitive detection and precise quantitation of trace-level crucial biomarkers in a complex sample matrix has become an important area of research.For example,the detection of high-sensitivity cardiac troponin I (hs-c...Sensitive detection and precise quantitation of trace-level crucial biomarkers in a complex sample matrix has become an important area of research.For example,the detection of high-sensitivity cardiac troponin I (hs-cTnI) is strongly recommended in clinical guidelines for early diagnosis of acute myocardial infarction.Based on the use of an electrode modified by single-walled carbon nanotubes (SWCNTs) and a Ru(bpy)32+-doped silica nanoparticle (Ru@SiO2)/tripropylamine (TPA) system,a novel type of electrochemiluminescent (ECL) magnetoimmunosensor is developed for ultrasensitive detection of hs-cTnI.In this approach,a large amount of[Ru(bpy)3]2+is loaded in SiO2(silica nanoparticles) as luminophores with high luminescent efficiency and SWCNTs as electrode surface modification material with excellent electrooxidation ability for TPA.Subsequently,a hierarchical micropillar array of microstructures is fabricated with a magnet placed at each end to efficiently confine a single layer of immunomagnetic microbeads on the surface of the electrode and enable 7.5-fold signal enhancement In particular,the use of transparent SWCNTs to modify a transparent ITO electrode provides a two-order-of-magnitude ECL signal amplification.A good linear calibration curve is developed for hs-cTnI concentrations over a wide range from 10 fg/ml to 10 ng/ml,with the limit of detection calculated as 8.720 fg/ml (S/N=3).This ultrasensitive immunosensor exhibits superior detection performance with remarkable stability,reproducibility,and selectivity.Satisfactory recoveries are obtained in the detection of hs-cTnI in human serum,providing a potentia analysis protocol for clinical applications.展开更多
Cancer metastasis is the leading cause of death in cancer patients worldwide and one of the major challenges in treating cancer.Circulating tumor cells(CTCs)play a pivotal role in cancer metastasis.However,the content...Cancer metastasis is the leading cause of death in cancer patients worldwide and one of the major challenges in treating cancer.Circulating tumor cells(CTCs)play a pivotal role in cancer metastasis.However,the content of CTCs in peripheral blood is minimal,so the detection of CTCs in real samples is extremely challenging.Therefore,efficient enrichment and early detection of CTCs are essential to achieve timely diagnosis of diseases.In this work,we constructed an innovative and sensitive single-nanoparticle collision electrochemistry(SNCE)biosensor for the detection of MCF-7 cells(human breast cancer cells)by immunomagnetic separation technique and liposome signal amplification strategy.Liposomes embedded with platinum nanoparticles(Pt NPs)were used as signal probes,and homemade gold ultramicroelectrodes(Au UME)were used as the working electrodes.The effective collision between Pt NPs and UME would produce distinguishable step-type current.MCF-7 cells were accurately quantified according to the relationship between cell concentration and collision frequency(the number of step-type currents generated per unit time),realizing highly sensitive and specific detection of MCF-7 cells.The SNCE biosensor has a linear range of 10 cells·mL^(-1)to 10^(5) cells·mL^(-1)with a detection limit as low as 5 cells·mL^(-1).In addition,the successful detection of MCF-7 cells in complex samples showed that the SNCE biosensors have great potential for patient sample detection.展开更多
We investigated the plasmon-exciton interactions in an individual gold nanorod(GNR)with monolayer MoS2 at room temperature with the single-particle spectroscopy technique.To control the plasmon-exciton interaction,we ...We investigated the plasmon-exciton interactions in an individual gold nanorod(GNR)with monolayer MoS2 at room temperature with the single-particle spectroscopy technique.To control the plasmon-exciton interaction,we tuned the local surface plasmon resonance of an individual GNR in-situ by employing the photothermal reshaping effect.The scattering spectra of the GNR-MoS2 hybrids exhibited two dips at the frequencies of the A and B excitons of monolayer MoS2,which were caused by the plasmon-induced resonance energy transfer effect.The resonance energy transfer rate increased when the surface plasmon resonance of the nanorod matched well with the exciton transition energy.Also,we demonstrated that the plasmon-enhanced fluorescence process dominated the photoluminescence of the GNR-MoS2 hybrid.These results provide a flexible way to control the plasmon-exciton interaction in an all-solid-state operating system at room temperature.展开更多
Acid phosphatase(ACP)is a ubiquitous phosphatase in living organisms.The abnormal variation of ACP is related to various diseases.Herein,we propose a colorimetric method based on CeO_(2)-modified gold core shell nanop...Acid phosphatase(ACP)is a ubiquitous phosphatase in living organisms.The abnormal variation of ACP is related to various diseases.Herein,we propose a colorimetric method based on CeO_(2)-modified gold core shell nanoparticles(Au@CeO_(2)NPs)to analyze ACP activity with high sensitivity and specificity.In this design,2-phospho-L-ascorbic acid trisodium salt(AAP)is dephosphorylated by ACP and produces reductive ascorbic acid(AA),which makes the CeO_(2)shell decomposition.A remarkable blue shift of localized surface plasmon resonance peak(LSPR,from yellow to green)along with the scattering intensity ratio changes from individual Au@CeO_(2)NPs are observed.ACP activity can be quantified by calculating the ratio changes of individual Au@CeO_(2)NPs.This assay reveals limit of detection(LOD)of 0.044 mU/mL and the linear range of 0.05–5.0 mU/mL,which are much lower than most of spectroscopic measurements in bulk solution.Furthermore,the recovery measurements in real samples are satisfactory and the capacity for practical application is demonstrated.As a consequence,Au@CeO_(2)NPs used in this assay will find new applications for the ultrasensitive detection of enzyme activity.展开更多
Electrochemical nitrate reduction to NH_(3)holds a great promise for N-upcycling in nature,while its sluggish reaction kinetics involved in both the stepwise deoxygenation and hydrogenation processes necessitates the ...Electrochemical nitrate reduction to NH_(3)holds a great promise for N-upcycling in nature,while its sluggish reaction kinetics involved in both the stepwise deoxygenation and hydrogenation processes necessitates the development of bespoke catalysts with multi-site engineering.Herein,we report a hybrid catalyst composed of rare-earth(RE)yttrium(Y)single atoms and copper phosphide(Cu_(3)P)nanoparticles loaded on N,P-doped carbon(Y_(SA)-Cu_(3)P/CNP)through a chelating and pyrolysis method.Owing to a synergistic contribution of Y single atoms and Cu_(3)P nanoparticles,Y_(SA)-Cu_(3)P/CNP achieves an impressive NH_(3)Faradaic efficiency(FE)of 92%at-0.5V(vs.RHE)and the highest NH_(3)yield rate of11.4 mg·h^(-1)·cm^(-2)at-0.6 V(vs.RHE)in an alkaline media,which surpass most of the reported electrocatalysts.The intricate reaction pathway has been explored by online differential electrochemical mass spectrometry(DEMS),and the synergistic effect between Y single atoms and Cu_(3)P nanoparticles has been studied by in situ synchrotron X-ray absorption spectroscopy.Moreover,density-functional theory(DFT)calculations unveil that the high-efficiency nitrate reduction on Y_(SA)-Cu_(3)P/CNP is attributed to a reduced energy barrier of the rate-determining deoxygenation step coupled with the enhanced stabilization of active hydrogen favorable for the hydrogenation steps,thereby boosting the overall reaction rates.In addition,a prototype Zn-nitrate battery utilizing Y_(SA)-Cu_(3)P/CNP as the cathode is unveiled.This work not only elucidates the mechanism behind the enhanced catalytic performance but also paves the way for the future development of highefficiency electrocatalysts through dual-site engineering.展开更多
In the present study,the nanofliud natural convection is investigated by the energy-conserving dissipative particle dynamics(eDPD)method,where the nanoparticles are considered at the single-particle level.The thermal ...In the present study,the nanofliud natural convection is investigated by the energy-conserving dissipative particle dynamics(eDPD)method,where the nanoparticles are considered at the single-particle level.The thermal expansion coefficientβand the viscosityμof the simulated system containing nanoparticles are calculated and found to be in close alignment with the previous simulation results.The single-particle hydrodynamics in e DPD enables simulations of nanofluid natural convection with higher Rayleigh numbers and greater nanoparticle volume fractions.Additionally,this approach is utilized to simulate the nanoparticle distribution during the enhanced heat transfer process in the nanofluid natural convection.The localized aggregation of nanoparticles enhances the heat transfer performance of the nanofluid under specific Rayleigh numbers and nanoparticles volume fractions.展开更多
A thermo-responsive rewritable plasmonic bio-memory chip has been successfully fabricated on an indium tin oxide(ITO)glass slide by assembling core-satellite gold nanoclusters with different size of gold nanoparticles...A thermo-responsive rewritable plasmonic bio-memory chip has been successfully fabricated on an indium tin oxide(ITO)glass slide by assembling core-satellite gold nanoclusters with different size of gold nanoparticles(AuNPs)using double-strand DNA(dsDNA)linker.And the prepared 70@DNA20@13 gold nanoclusters(AuNCs)exhibited more stable and greater photothermal conversion ability.With short time irradiation by 633 nm microbeam laser,every individual AuNCs could be excited and remove the satellite AuNPs on its surface.Especially,in the dissociation process of AuNCs with 3−5 satellite,its color would change from yellow to green,which showed more significant reduction in the red channel of the dark-field microscopy(DFM)images and could be defined to state“0”and“1”respectively.Besides,this plasmonic nano bio-memory could transform cyclically its state between 0 and 1 which exhibited excellent rewritable ability.展开更多
Isothermal methods, such as helicase-dependent amplification （HDA）, have an advantage over polymerase chain reaction for DNA amplification owing to their ease of operation. Here, we developed a new HDA method that i...Isothermal methods, such as helicase-dependent amplification （HDA）, have an advantage over polymerase chain reaction for DNA amplification owing to their ease of operation. Here, we developed a new HDA method that is nanoparticle-assisted, termed nanoHDA. This method uses gold nanoparticles （AuNPs） to improve the sensitivity and specificity of the isothermal method. In HDA, the denaturation of DNA templates is mediated by helicases, but this method is limited by the low denaturation efficiency of helicases. In this report, AuNPs with preferential affinity for single-stranded DNA （ssDNA） were utilized to improve the denaturation efficiency of helicases. The same affinity property of nanoparticles can also enhance specificity by suppressing primer-dimer formation. This nanoHDA method was employed to genotype the KRAS gene in genomic DNA samples from colorectal cancer patients, as achieved by the hybridization of nanoHDA amplicons using the NanoBioArray chip.展开更多
The resolution of conventional optical microscopy is only -200 nm, which is becoming less and less sufficient for a variety of applications. In order to surpass the diffraction limited resolution, super-resolution mic...The resolution of conventional optical microscopy is only -200 nm, which is becoming less and less sufficient for a variety of applications. In order to surpass the diffraction limited resolution, super-resolution microscopy （SRM） has been developed to achieve a high resolution of one to tens of nanometers. The techniques involved in SRM can be assigned into two broad categories, namely ＂true＂ super-resolution techniques and ＂functional＂ super-resolution techniques. In ＂functional＂ super-resolution techniques, stochastic super-resolution microscopy （SSRM） is widely used due to its low expense, simple operation, and high resolution. The principle process in SSRM is to accumulate the coordinates of many diffraction-limited emitters （e.g., single fluorescent molecules） on the object by localizing the centroids of the point spread functions （PSF）, and then reconstruct the image of the object using these coordinates. When the diffraction-limited emitters take part in a catalytic reaction, the activity distribution and kinetic information about the catalysis by nanoparticles can be obtained by SSRM. SSRM has been applied and exhibited outstanding advantages in several fields of catalysis, such as metal nanoparticle catalysis, molecular sieve catalysis, and photocatalysis. Since SSRM is able to resolve the catalytic activity within one nanoparticle, it promises to accelerate the development and discovery of new and better catalysts. This review will present a brief introduction to SRM, and a detailed description of SSRM and its applications in nano-catalysis.展开更多
The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐co...The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.展开更多
Nanocollision electrochemistry is employed to evaluate the ORR’s activity of one single Pt nanoparticle,the effect of the size and ligand is investigated.The size-normalized activity of the Pt nanoparticle of 4 nm is...Nanocollision electrochemistry is employed to evaluate the ORR’s activity of one single Pt nanoparticle,the effect of the size and ligand is investigated.The size-normalized activity of the Pt nanoparticle of 4 nm is two times higher than that of 25 nm,confirming that the intrinsic activity does depend on the size of the nanoparticles.It is further found that the adsorbed ligand does yield effect on electrocatalysis,and the adsorption strength follows the order of PVP>CTAB>citrate.This work is of significance to understand the nature of the ORR’s electrocatalysis at the level of an individual entity,which makes the structure-activity correlation in a more reliable way.展开更多
Ensemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core-shell β-NaYF_(4):Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb^(3+) and...Ensemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core-shell β-NaYF_(4):Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb^(3+) and 1% or 3% Er^(^(3+)) performed over a P regime of 6 orders of magnitude reveal an increasing contribution of the emission from high energy Er^(3+) levels at P > 1 kW/cm^(2). This changes the overall emission color from initially green over yellow to white. While initially the green and with increasing P the red emission dominate in ensemble measurements at P < 1 kW/cm^(2), the increasing population of higher Er^(^(3+)) energy levels by multiphotonic processes at higher P in single particle studies results in a multitude of emission bands in the ultraviolet/visible/near infrared (UV/vis/NIR) accompanied by a decreased contribution of the red luminescence. Based upon a thorough analysis of the P-dependence of UCL, the emission bands activated at high P were grouped and assigned to 2–3, 3–4, and 4 photonic processes involving energy transfer (ET), excited-state absorption (ESA), cross-relaxation (CR), back energy transfer (BET), and non-radiative relaxation processes (nRP). This underlines the P-tunability of UCNP brightness and color and highlights the potential of P-dependent measurements for mechanistic studies required to manifest the population pathways of the different Er^(3+) levels.展开更多
Owing to their structural dispersion,the catalytic properties of nanoparticles are challenging to characterize in ensemble-averaged measurements.The single-molecule approach enables studying the catalysis of nanoparti...Owing to their structural dispersion,the catalytic properties of nanoparticles are challenging to characterize in ensemble-averaged measurements.The single-molecule approach enables studying the catalysis of nanoparticles at the single-particle level with real-time single-turnover resolution.This article reviews our single-molecule fluorescence studies of single Au-nanoparticle catalysis,focusing on the theoretical formulations for extracting quantitative reaction kinetics from the single-turnover resolution catalysis trajectories.We discuss the single-molecule kinetic formulism of the Langmuir-Hinshelwood mechanism for heterogeneous catalysis,as well as of the two-pathway model for product dissociation reactions.This formulism enables the quantitative evaluation of the heterogeneous reactivity and the differential selectivity of individual nanoparticles that are usually hidden in ensemble measurements.Extension of this formulism to single-molecule catalytic kinetics of oligomeric enzymes is also discussed.展开更多
There is an increasing demand for new technologies to rapidly measure individual nanoparticles in situ for applications,including early-stage diagnosis of human diseases and environmental monitoring.Here,we demonstrat...There is an increasing demand for new technologies to rapidly measure individual nanoparticles in situ for applications,including early-stage diagnosis of human diseases and environmental monitoring.Here,we demonstrate a label-free wide-field optical microscopy capable of sizing dispersed non-luminescent dielectric nanoparticles(with diameters down to 22 nm)with 10 nm accuracy.This technique utilizes enhanced nanoparticle-perturbed scattering by surface plasmons created on a gold film.In the meantime,an azimuthal rotation illumination module is installed on this microscope and a differential image processing technique is carried out.The relationship between the scattering intensity and the particle size was experimentally measured with good consistency with the theoretical prediction.The capability of precise measurement of the size of dispersed nanoparticles within a larger field of view in a label-free,non-invasive and quantitative manner may find broad applications involving single nanoparticle chemistry and physics.展开更多
A novel, cost effective, sonochemical-hydrothermal technique was used for the deposition of nanosized anatase titanium dioxide (TiO2) onto single wall carbon nanotubes (SWCNTs). This technique is described and the cha...A novel, cost effective, sonochemical-hydrothermal technique was used for the deposition of nanosized anatase titanium dioxide (TiO2) onto single wall carbon nanotubes (SWCNTs). This technique is described and the characterization of the synthesized TiO2-SWCNTs is reported. The characterization techniques employed include scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). From the characterization the size and morphology of the synthesized TiO2 nanoparticles (deposited on the SWCNTs) are reported. Furthermore, it is demonstrated that the created TiO2 nanoparticles are chemically attached to the SWCNTs. Also, an important correlation between calculated TiO2 crystal size and the red shifts in the lowest Raman TiO2 (E.g.) predominate peak is reported. The synthesized TiO2-SWCNTs have potential for large scale production and application in a variety of new technologies such as clean energy power generation devices, electrical storage devices, photocatalysts, and sensors.展开更多
Optical modeling coupled to experiments show that a microscope operating in reflection mode allows imaging,through solutions or even a microfluidic cover,various kinds of nanoparticles,NPs,over a(reflecting)sensing su...Optical modeling coupled to experiments show that a microscope operating in reflection mode allows imaging,through solutions or even a microfluidic cover,various kinds of nanoparticles,NPs,over a(reflecting)sensing surface,here a gold(Au)surface.Optical modeling suggests that this configuration enables the interferometric imaging of single NPs which can be characterized individually from local change in the surface reflectivity.The interferometric detection improves the optical limit of detection compared to classical configurations exploiting only the light scattered by the NPs.The method is then tested experimentally,to monitor in situ and in real time,the collision of single Brownian NPs,or optical nanoimpacts,with an Au-sensing surface.First,mimicking a microfluidic biosensor platform,the capture of 300 nm FeOx maghemite NPs from a convective flow by a surface-functionalized Au surface is dynamically monitored.Then,the adsorption or bouncing of individual dielectric(100 nm polystyrene)or metallic(40 and 60 nm silver)NPs is observed directly through the solution.The influence of the electrolyte on the ability of NPs to repetitively bounce or irreversibly adsorb onto the Au surface is evidenced.Exploiting such visualization mode of single-NP optical nanoimpacts is insightful for comprehending single-NP electrochemical studies relying on NP collision on an electrode(electrochemical nanoimpacts).展开更多
基金This work was supported by the National Natural Science Foundation of China(No.21701112)Science,Technology and Innovation Committee of Shenzhen Municipality(No.JCYJ20170303160036674)+2 种基金Hong Kong Research Grants Council(PolyU153062/18R C4006-17G and HKUST16304117)the Hong Kong Polytechnic University(1-ZE1C)Ms Clarea Au(847S)for the Endowed Professorship in Energy.Special thanks were also given to Instrumental Analysis Center of Shenzhen University(Xili Campus).
文摘L10-FePt nan oparticles(NPs)with high chemical ordering represent effective electrocatalysts to reduce the cost and enhance theircatalytic performanee in fuel cells.A molecular strategy of preparing highly ordered FePt NPs was used by direct pyrolysis of a Fe,Pt-containing bimetallic complex.The resultant L10-FePt NPs had very high crystallinity as reflected by the obvious diffractionpatterns,clear lattice fringes and characteristic X-ray diffraction peaks,etc.Besides,the strong ferromagnetism with room temperaturecoercivity of 27 kOe further confirmed the face-centered tetrag on al(fet)phase in good agreement with the ordered nano structures.TheFePt NPs can be used as electrocatalysts to catalyze oxygen reduction reaction(ORR)in an O2·saturated 0.1 M HClO4 solution andhydrogen evolution reaction(HER)in the 0.5 M H2SO4 electrolyte with much better performance than commercial Pt/C,and showedquite high stability after 10,000 cycles.The strategy utilizing orga no metallic precursors to prepare metal alloy NPs was dem on strated tobe a reliable approach for improving the catalytic efficiency in fuel cells.
基金We appreciate the financial support from the National Natural Science Foundation of China(22272150,22102145)the Major Program of Zhejiang Provincial Natural Science Foundation(LD22B030002)+3 种基金Zhejiang Provincial Ten Thousand Talent Program(2021R51009)Zhejiang Provincial Natural Science Foundation of China(LQ23B030006,LY22B030012)Shandong Provincial Natural Science Foundation of China(2020MB053)the Fundamental Research Funds for the Central Universities(DUT22RC(3)084).
文摘Modulating electronic structures of single-atom metal cocatalysts is vital for highly active photoreduction of CO_(2),and it's especially challenging to develop a facile method to modify the dispersion of atomical photocatalytic sites.We herein report an ion-loading pyrolysis route to in-situ anchor Pd single atoms as well as twinned Pd nanoparticles on ultra-thin graphitic carbon nitride nanosheets(PdTP/Pd_(SA)-CN)for high-efficiency photoreduction of CO_(2).The anchored Pd twinned nanoparticles donate electrons to adjacent single Pd–N_(4) sites through the carbon nitride networks,and the optimized PdTP/Pd_(SA)-CN photocatalyst exhibits a CO evolution rate up to 46.5μmol g^(-1) h^(-1) with nearly 100%selectivity.As revealed by spectroscopic and theoretical analyses,the superior photocatalytic activity is attributed to the lowered desorption barrier of carbonyl species at electron-enriched Pd single atoms,together with the improved efficiencies of light-harvesting and charge separation/transport.This work has demonstrated the engineering of the electron density of single active sites with twinned metal nanoparticles assisted by strong electronic interaction with the support of the atomic metal,and unveiled the underlying mechanism for expedited photocatalytic efficiency.
基金The authors acknowledge financial support from the National Natural Science Foundation of China(Grant Nos.62001460,31971368,12202461,and 22104148)the Guangdong Regional Joint Funds for Young Scientists(Grant Nos.2020A1515110201 and 2020A1515110368)+2 种基金Guangdong Provincial General Funding(Grant No.2021A1515220156)Guangdong Basic and Applied Basic Research Funding-Regional Joint Fund(Grant No.2020B1515120040)Shenzhen Science and Technology Research Funding(Grant Nos.JSGG20201103153801005,JSGG20191115141601721,ZDSYS20220527171406014,JCYJ20220818101412027,JCYJ20200109115635440,and JCYJ 20200109115408041).
文摘Sensitive detection and precise quantitation of trace-level crucial biomarkers in a complex sample matrix has become an important area of research.For example,the detection of high-sensitivity cardiac troponin I (hs-cTnI) is strongly recommended in clinical guidelines for early diagnosis of acute myocardial infarction.Based on the use of an electrode modified by single-walled carbon nanotubes (SWCNTs) and a Ru(bpy)32+-doped silica nanoparticle (Ru@SiO2)/tripropylamine (TPA) system,a novel type of electrochemiluminescent (ECL) magnetoimmunosensor is developed for ultrasensitive detection of hs-cTnI.In this approach,a large amount of[Ru(bpy)3]2+is loaded in SiO2(silica nanoparticles) as luminophores with high luminescent efficiency and SWCNTs as electrode surface modification material with excellent electrooxidation ability for TPA.Subsequently,a hierarchical micropillar array of microstructures is fabricated with a magnet placed at each end to efficiently confine a single layer of immunomagnetic microbeads on the surface of the electrode and enable 7.5-fold signal enhancement In particular,the use of transparent SWCNTs to modify a transparent ITO electrode provides a two-order-of-magnitude ECL signal amplification.A good linear calibration curve is developed for hs-cTnI concentrations over a wide range from 10 fg/ml to 10 ng/ml,with the limit of detection calculated as 8.720 fg/ml (S/N=3).This ultrasensitive immunosensor exhibits superior detection performance with remarkable stability,reproducibility,and selectivity.Satisfactory recoveries are obtained in the detection of hs-cTnI in human serum,providing a potentia analysis protocol for clinical applications.
基金supported by the National Natural Science Foundation of China(Nos.22274037,22376055 and 21904032)the Natural Science Foundation of Hubei Province(2022CFB383)。
文摘Cancer metastasis is the leading cause of death in cancer patients worldwide and one of the major challenges in treating cancer.Circulating tumor cells(CTCs)play a pivotal role in cancer metastasis.However,the content of CTCs in peripheral blood is minimal,so the detection of CTCs in real samples is extremely challenging.Therefore,efficient enrichment and early detection of CTCs are essential to achieve timely diagnosis of diseases.In this work,we constructed an innovative and sensitive single-nanoparticle collision electrochemistry(SNCE)biosensor for the detection of MCF-7 cells(human breast cancer cells)by immunomagnetic separation technique and liposome signal amplification strategy.Liposomes embedded with platinum nanoparticles(Pt NPs)were used as signal probes,and homemade gold ultramicroelectrodes(Au UME)were used as the working electrodes.The effective collision between Pt NPs and UME would produce distinguishable step-type current.MCF-7 cells were accurately quantified according to the relationship between cell concentration and collision frequency(the number of step-type currents generated per unit time),realizing highly sensitive and specific detection of MCF-7 cells.The SNCE biosensor has a linear range of 10 cells·mL^(-1)to 10^(5) cells·mL^(-1)with a detection limit as low as 5 cells·mL^(-1).In addition,the successful detection of MCF-7 cells in complex samples showed that the SNCE biosensors have great potential for patient sample detection.
基金This work was supported by the National Key Research and Development Program of China(grant No.2018YFB2200401)the National Natural Science Foundation of China(grant Nos.91950111,61521004 and 11527901).
文摘We investigated the plasmon-exciton interactions in an individual gold nanorod(GNR)with monolayer MoS2 at room temperature with the single-particle spectroscopy technique.To control the plasmon-exciton interaction,we tuned the local surface plasmon resonance of an individual GNR in-situ by employing the photothermal reshaping effect.The scattering spectra of the GNR-MoS2 hybrids exhibited two dips at the frequencies of the A and B excitons of monolayer MoS2,which were caused by the plasmon-induced resonance energy transfer effect.The resonance energy transfer rate increased when the surface plasmon resonance of the nanorod matched well with the exciton transition energy.Also,we demonstrated that the plasmon-enhanced fluorescence process dominated the photoluminescence of the GNR-MoS2 hybrid.These results provide a flexible way to control the plasmon-exciton interaction in an all-solid-state operating system at room temperature.
基金supported by the Natural Science Foundation of Hunan Province,China(No.2022JJ40266)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University,China(No.2022A04).
文摘Acid phosphatase(ACP)is a ubiquitous phosphatase in living organisms.The abnormal variation of ACP is related to various diseases.Herein,we propose a colorimetric method based on CeO_(2)-modified gold core shell nanoparticles(Au@CeO_(2)NPs)to analyze ACP activity with high sensitivity and specificity.In this design,2-phospho-L-ascorbic acid trisodium salt(AAP)is dephosphorylated by ACP and produces reductive ascorbic acid(AA),which makes the CeO_(2)shell decomposition.A remarkable blue shift of localized surface plasmon resonance peak(LSPR,from yellow to green)along with the scattering intensity ratio changes from individual Au@CeO_(2)NPs are observed.ACP activity can be quantified by calculating the ratio changes of individual Au@CeO_(2)NPs.This assay reveals limit of detection(LOD)of 0.044 mU/mL and the linear range of 0.05–5.0 mU/mL,which are much lower than most of spectroscopic measurements in bulk solution.Furthermore,the recovery measurements in real samples are satisfactory and the capacity for practical application is demonstrated.As a consequence,Au@CeO_(2)NPs used in this assay will find new applications for the ultrasensitive detection of enzyme activity.
基金financially supported by the National Key Research and Development Program of China(Nos.2022YFA1505700 and 2019YFA0210403)the National Natural Science Foundation of China(Nos.22205232 and 21601187)+2 种基金the Talent Plan of Shanghai Branch,Chinese Academy of Sciences(No.CASSHB-QNPD-2023-020)the Natural Science Foundation of Fujian Province(Nos.2023J06044 and 2023J01213)the Fund for Distinguished Young Scholars of FJIRSM(No.CXZX-2022-JQ06)。
文摘Electrochemical nitrate reduction to NH_(3)holds a great promise for N-upcycling in nature,while its sluggish reaction kinetics involved in both the stepwise deoxygenation and hydrogenation processes necessitates the development of bespoke catalysts with multi-site engineering.Herein,we report a hybrid catalyst composed of rare-earth(RE)yttrium(Y)single atoms and copper phosphide(Cu_(3)P)nanoparticles loaded on N,P-doped carbon(Y_(SA)-Cu_(3)P/CNP)through a chelating and pyrolysis method.Owing to a synergistic contribution of Y single atoms and Cu_(3)P nanoparticles,Y_(SA)-Cu_(3)P/CNP achieves an impressive NH_(3)Faradaic efficiency(FE)of 92%at-0.5V(vs.RHE)and the highest NH_(3)yield rate of11.4 mg·h^(-1)·cm^(-2)at-0.6 V(vs.RHE)in an alkaline media,which surpass most of the reported electrocatalysts.The intricate reaction pathway has been explored by online differential electrochemical mass spectrometry(DEMS),and the synergistic effect between Y single atoms and Cu_(3)P nanoparticles has been studied by in situ synchrotron X-ray absorption spectroscopy.Moreover,density-functional theory(DFT)calculations unveil that the high-efficiency nitrate reduction on Y_(SA)-Cu_(3)P/CNP is attributed to a reduced energy barrier of the rate-determining deoxygenation step coupled with the enhanced stabilization of active hydrogen favorable for the hydrogenation steps,thereby boosting the overall reaction rates.In addition,a prototype Zn-nitrate battery utilizing Y_(SA)-Cu_(3)P/CNP as the cathode is unveiled.This work not only elucidates the mechanism behind the enhanced catalytic performance but also paves the way for the future development of highefficiency electrocatalysts through dual-site engineering.
基金Project supported by the National Natural Science Foundation of China(Nos.11872283 and 2002212)the Sailing Program of Shanghai,China(No.20YF1432800)。
文摘In the present study,the nanofliud natural convection is investigated by the energy-conserving dissipative particle dynamics(eDPD)method,where the nanoparticles are considered at the single-particle level.The thermal expansion coefficientβand the viscosityμof the simulated system containing nanoparticles are calculated and found to be in close alignment with the previous simulation results.The single-particle hydrodynamics in e DPD enables simulations of nanofluid natural convection with higher Rayleigh numbers and greater nanoparticle volume fractions.Additionally,this approach is utilized to simulate the nanoparticle distribution during the enhanced heat transfer process in the nanofluid natural convection.The localized aggregation of nanoparticles enhances the heat transfer performance of the nanofluid under specific Rayleigh numbers and nanoparticles volume fractions.
基金the National Natural Science Foundation of China(NSFC,Nos.22204081,62075103,and 22374081)Project of State Key Laboratory of Organic Electronics and Information Displays,Nanjing University of Posts and Telecommunications(No.20230112)+1 种基金Natural Science Foundation of Jiangsu Province(No.BK20211271)State Key Laboratory of Analytical Chemistry for Life Science(No.SKLACLS2210).
文摘A thermo-responsive rewritable plasmonic bio-memory chip has been successfully fabricated on an indium tin oxide(ITO)glass slide by assembling core-satellite gold nanoclusters with different size of gold nanoparticles(AuNPs)using double-strand DNA(dsDNA)linker.And the prepared 70@DNA20@13 gold nanoclusters(AuNCs)exhibited more stable and greater photothermal conversion ability.With short time irradiation by 633 nm microbeam laser,every individual AuNCs could be excited and remove the satellite AuNPs on its surface.Especially,in the dissociation process of AuNCs with 3−5 satellite,its color would change from yellow to green,which showed more significant reduction in the red channel of the dark-field microscopy(DFM)images and could be defined to state“0”and“1”respectively.Besides,this plasmonic nano bio-memory could transform cyclically its state between 0 and 1 which exhibited excellent rewritable ability.
文摘Isothermal methods, such as helicase-dependent amplification （HDA）, have an advantage over polymerase chain reaction for DNA amplification owing to their ease of operation. Here, we developed a new HDA method that is nanoparticle-assisted, termed nanoHDA. This method uses gold nanoparticles （AuNPs） to improve the sensitivity and specificity of the isothermal method. In HDA, the denaturation of DNA templates is mediated by helicases, but this method is limited by the low denaturation efficiency of helicases. In this report, AuNPs with preferential affinity for single-stranded DNA （ssDNA） were utilized to improve the denaturation efficiency of helicases. The same affinity property of nanoparticles can also enhance specificity by suppressing primer-dimer formation. This nanoHDA method was employed to genotype the KRAS gene in genomic DNA samples from colorectal cancer patients, as achieved by the hybridization of nanoHDA amplicons using the NanoBioArray chip.
文摘The resolution of conventional optical microscopy is only -200 nm, which is becoming less and less sufficient for a variety of applications. In order to surpass the diffraction limited resolution, super-resolution microscopy （SRM） has been developed to achieve a high resolution of one to tens of nanometers. The techniques involved in SRM can be assigned into two broad categories, namely ＂true＂ super-resolution techniques and ＂functional＂ super-resolution techniques. In ＂functional＂ super-resolution techniques, stochastic super-resolution microscopy （SSRM） is widely used due to its low expense, simple operation, and high resolution. The principle process in SSRM is to accumulate the coordinates of many diffraction-limited emitters （e.g., single fluorescent molecules） on the object by localizing the centroids of the point spread functions （PSF）, and then reconstruct the image of the object using these coordinates. When the diffraction-limited emitters take part in a catalytic reaction, the activity distribution and kinetic information about the catalysis by nanoparticles can be obtained by SSRM. SSRM has been applied and exhibited outstanding advantages in several fields of catalysis, such as metal nanoparticle catalysis, molecular sieve catalysis, and photocatalysis. Since SSRM is able to resolve the catalytic activity within one nanoparticle, it promises to accelerate the development and discovery of new and better catalysts. This review will present a brief introduction to SRM, and a detailed description of SSRM and its applications in nano-catalysis.
文摘The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.
基金jointly supported by the National Natural Science Foundation of China(Nos.21903026,21975081,21975079,21676106)Science and Technology Program of Guangdong Province(2017A050506015)+2 种基金Science and Technology Program of Guangzhou(201704030065)China Postdoctoral Science Foundation(2019M652877)the Fundamental Research Funds for the Central Universities。
文摘Nanocollision electrochemistry is employed to evaluate the ORR’s activity of one single Pt nanoparticle,the effect of the size and ligand is investigated.The size-normalized activity of the Pt nanoparticle of 4 nm is two times higher than that of 25 nm,confirming that the intrinsic activity does depend on the size of the nanoparticles.It is further found that the adsorbed ligand does yield effect on electrocatalysis,and the adsorption strength follows the order of PVP>CTAB>citrate.This work is of significance to understand the nature of the ORR’s electrocatalysis at the level of an individual entity,which makes the structure-activity correlation in a more reliable way.
基金The authors thank the European Upconversion Network(EUN)for financial support of a research exchange program(COST-CM1403)U.R.-G.,F.F.and C.W.acknowledge financial support by research grants RE 1203/20-1(project NANOHYPE,DFG and M-Eranet).Y.M.is grateful to the Institut Universitaire de France(IUF)for support and providing additional time to be dedicated to research.
文摘Ensemble and single particle studies of the excitation power density (P)-dependent upconversion luminescence (UCL) of core and core-shell β-NaYF_(4):Yb,Er upconversion nanoparticles (UCNPs) doped with 20% Yb^(3+) and 1% or 3% Er^(^(3+)) performed over a P regime of 6 orders of magnitude reveal an increasing contribution of the emission from high energy Er^(3+) levels at P > 1 kW/cm^(2). This changes the overall emission color from initially green over yellow to white. While initially the green and with increasing P the red emission dominate in ensemble measurements at P < 1 kW/cm^(2), the increasing population of higher Er^(^(3+)) energy levels by multiphotonic processes at higher P in single particle studies results in a multitude of emission bands in the ultraviolet/visible/near infrared (UV/vis/NIR) accompanied by a decreased contribution of the red luminescence. Based upon a thorough analysis of the P-dependence of UCL, the emission bands activated at high P were grouped and assigned to 2–3, 3–4, and 4 photonic processes involving energy transfer (ET), excited-state absorption (ESA), cross-relaxation (CR), back energy transfer (BET), and non-radiative relaxation processes (nRP). This underlines the P-tunability of UCNP brightness and color and highlights the potential of P-dependent measurements for mechanistic studies required to manifest the population pathways of the different Er^(3+) levels.
基金We thank the Army Research Office(56355-CH)National Science Foundation(NSF,No.CBET 0851257)+1 种基金American Chemical Society Petroleum Research Foundation(No.47918-G5)NSF-funded Cornell Center for Materials Research for fi nancial support。
文摘Owing to their structural dispersion,the catalytic properties of nanoparticles are challenging to characterize in ensemble-averaged measurements.The single-molecule approach enables studying the catalysis of nanoparticles at the single-particle level with real-time single-turnover resolution.This article reviews our single-molecule fluorescence studies of single Au-nanoparticle catalysis,focusing on the theoretical formulations for extracting quantitative reaction kinetics from the single-turnover resolution catalysis trajectories.We discuss the single-molecule kinetic formulism of the Langmuir-Hinshelwood mechanism for heterogeneous catalysis,as well as of the two-pathway model for product dissociation reactions.This formulism enables the quantitative evaluation of the heterogeneous reactivity and the differential selectivity of individual nanoparticles that are usually hidden in ensemble measurements.Extension of this formulism to single-molecule catalytic kinetics of oligomeric enzymes is also discussed.
基金the Ministry of Science and Technology of China(Grant No.2016YFA0200601)National Natural Science Foundation of China(Grant Nos.11774330,92050202,and U20A20216)+5 种基金Anhui Initiative in Quantum Information Technologies(Grant No.AHY090000)Advanced Laser Technology Laboratory of Anhui Province(Grant No.20192301)Hefei Municipal Natural Science Foundation(Grant No.2021007)Key Research&Development Program of Anhui Province(Grant No.202104a05020010)J.R.Lakowicz thanks the National Institute of General Medical Sciences(Grant Nos.R01 GM125976,and R21 GM129561)National Institutes of Health(Grant Nos.S10OD19975,and S10RR026370)for support.
文摘There is an increasing demand for new technologies to rapidly measure individual nanoparticles in situ for applications,including early-stage diagnosis of human diseases and environmental monitoring.Here,we demonstrate a label-free wide-field optical microscopy capable of sizing dispersed non-luminescent dielectric nanoparticles(with diameters down to 22 nm)with 10 nm accuracy.This technique utilizes enhanced nanoparticle-perturbed scattering by surface plasmons created on a gold film.In the meantime,an azimuthal rotation illumination module is installed on this microscope and a differential image processing technique is carried out.The relationship between the scattering intensity and the particle size was experimentally measured with good consistency with the theoretical prediction.The capability of precise measurement of the size of dispersed nanoparticles within a larger field of view in a label-free,non-invasive and quantitative manner may find broad applications involving single nanoparticle chemistry and physics.
文摘A novel, cost effective, sonochemical-hydrothermal technique was used for the deposition of nanosized anatase titanium dioxide (TiO2) onto single wall carbon nanotubes (SWCNTs). This technique is described and the characterization of the synthesized TiO2-SWCNTs is reported. The characterization techniques employed include scanning electron microscopy (SEM), Raman spectroscopy, and X-ray diffraction (XRD). From the characterization the size and morphology of the synthesized TiO2 nanoparticles (deposited on the SWCNTs) are reported. Furthermore, it is demonstrated that the created TiO2 nanoparticles are chemically attached to the SWCNTs. Also, an important correlation between calculated TiO2 crystal size and the red shifts in the lowest Raman TiO2 (E.g.) predominate peak is reported. The synthesized TiO2-SWCNTs have potential for large scale production and application in a variety of new technologies such as clean energy power generation devices, electrical storage devices, photocatalysts, and sensors.
基金We are grateful for financial support by the Agence Nationale pour la Recherche(NEOCASTIP ANR-15-CE09-0015-02 project)Direction Générale de l’Armement(AMMIB ANR-13-ASTR-0021-01),by Universities Paris Diderot and Paris Sud and by CNRS.
文摘Optical modeling coupled to experiments show that a microscope operating in reflection mode allows imaging,through solutions or even a microfluidic cover,various kinds of nanoparticles,NPs,over a(reflecting)sensing surface,here a gold(Au)surface.Optical modeling suggests that this configuration enables the interferometric imaging of single NPs which can be characterized individually from local change in the surface reflectivity.The interferometric detection improves the optical limit of detection compared to classical configurations exploiting only the light scattered by the NPs.The method is then tested experimentally,to monitor in situ and in real time,the collision of single Brownian NPs,or optical nanoimpacts,with an Au-sensing surface.First,mimicking a microfluidic biosensor platform,the capture of 300 nm FeOx maghemite NPs from a convective flow by a surface-functionalized Au surface is dynamically monitored.Then,the adsorption or bouncing of individual dielectric(100 nm polystyrene)or metallic(40 and 60 nm silver)NPs is observed directly through the solution.The influence of the electrolyte on the ability of NPs to repetitively bounce or irreversibly adsorb onto the Au surface is evidenced.Exploiting such visualization mode of single-NP optical nanoimpacts is insightful for comprehending single-NP electrochemical studies relying on NP collision on an electrode(electrochemical nanoimpacts).
