We have developed a simple method for fabricating robust and low noise glass nanopore electrodes with pore size 10±5 nm to detect single molecules.β-Cyclodextrin was used as model compound for characterization.I...We have developed a simple method for fabricating robust and low noise glass nanopore electrodes with pore size 10±5 nm to detect single molecules.β-Cyclodextrin was used as model compound for characterization.In 1.0 mol/L NaCl solution,the molecules generated current pulses of 2-5 pA with noise level less than 0.8 pA.A slide mode and a plug mode were suggested for the way ofβ-cyclodextrin single molecule moving into the glass nanopores.展开更多
Single-molecule detection and imaging are of great value in chemical analysis,biomarker identification and other trace detection fields.However,the localization and visualization of single molecule are still quite a c...Single-molecule detection and imaging are of great value in chemical analysis,biomarker identification and other trace detection fields.However,the localization and visualization of single molecule are still quite a challenge.Here,we report a special-engineered nanostructure of Ag nanoparticles embedded in multi-layer black phosphorus nanosheets(Ag/BP-NS)synthesized by a unique photoreduction method as a surfaceenhanced Raman scattering(SERS)sensor.Such a SERS substrate features the lowest detection limit of 10^(–20) mol L^(−1) for R6G,which is due to the three synergistic resonance enhancement of molecular resonance,photoinduced charge transfer resonance and electromagnetic resonance.We propose a polarization-mapping strategy to realize the detection and visualization of single molecule.In addition,combined with machine learning,Ag/BP-NS substrates are capable of recognition of different tumor exosomes,which is meaningful for monitoring and early warning of the cancer.This work provides a reliable strategy for the detection of single molecule and a potential candidate for the practical bio-application of SERS technology.展开更多
This paper reports the plasmonic lasing of a split ring filled with gain material in water. The lasing mode(1500 nm)is far from the pump mode(980 nm), which can depress the detection noise from the pump light. The...This paper reports the plasmonic lasing of a split ring filled with gain material in water. The lasing mode(1500 nm)is far from the pump mode(980 nm), which can depress the detection noise from the pump light. The laser intensities of the two modes simultaneously increase by more than 10^3 in amplitude, which can intensify the absorption efficiency of the pumping light and enhance the plasmonic lasing. The plasmonic lasing is a sensitive sensor. When a single protein nanoparticle(n = 1.5, r = 1.25 nm) is trapped in the gap of the split ring, the lasing spectrum moves by 0.031 nm, which is much larger than the detection limit of 10^-5 nm. Moreover, the lasing intensity is also very sensitive to the trapped nanoparticle. It reduces to less than 1/600 when a protein nanoparticle(n = 1.5, r = 1.25 nm) is trapped in the gap.展开更多
The exosome-mediated response can promote or restrain the diseases by regulating the intracellular pathways,making the exosome become an effective marker for diagnosis and therapeutic control at the single-cell level....The exosome-mediated response can promote or restrain the diseases by regulating the intracellular pathways,making the exosome become an effective marker for diagnosis and therapeutic control at the single-cell level.However,real-time analysis is hard to be achieved with traditional approaches because the exosomes usually need to be enriched by ultracentrifugation for a measurable signal-to-noise ratio.Recently developed label-free single-molecule imaging approaches may become an real-time quantitative tool for the analysis of single exosomes and related secretion behaviors of single living cells owing to their extreme sensitivity.展开更多
A single molecule detection technique was developed by the combination of a single channel poly (dimethylsiloxane)/glass micro-fluidic chip and fluorescence correlation spectroscopy (FCS). This method was successf...A single molecule detection technique was developed by the combination of a single channel poly (dimethylsiloxane)/glass micro-fluidic chip and fluorescence correlation spectroscopy (FCS). This method was successfully used to determine the proportion of two model components in the mixture containing fluorescein and the rhodamine-green succinimidyl ester.展开更多
The DNA G quadruplex formed by the human telomeric sequence is a potential target for novel anticancer drugs. We have investigated an intramolecular DNA G quadruplex using single molecule fluorescence resonance energy...The DNA G quadruplex formed by the human telomeric sequence is a potential target for novel anticancer drugs. We have investigated an intramolecular DNA G quadruplex using single molecule fluorescence resonance energy transfer and shown that individual folded quadruplexes can be identified. The mean proximity ratio measured at the single molecule level was consistent with ensemble measurement展开更多
Biosensors featuring single molecule detection present huge opportunities as well as challenges in food safety inspection,disease diagnosis,and environmental monitoring.Single-molecule detection is largely lacking of ...Biosensors featuring single molecule detection present huge opportunities as well as challenges in food safety inspection,disease diagnosis,and environmental monitoring.Single-molecule detection is largely lacking of high enough activity,precision molecule selectivity,and understanding in the exact operating mechanism.Single-atom catalysts(SACs),especially those metals-nitrogen-carbon that mimic the natural metalloenzyme structure,and with well-defined metal atom bond configurations,high level of molecular selectivity,and easy fabrication,endow single molecule detections with practical-use feasibilities.The recent advances in single-atom catalysts also present new pathways in the key mechanism understandings.In this short review,we will first visit the brief history and advantages of SACs that have been explored only recently for molecule-scale biosensors,where they are analogous and also differentiated from those nanozymes and natural metalloenzymes.Their applications in electrochemical,photochemical,and photoelectrochemical sensors are then discussed comprehensively by focusing on the different molecule-scale sensing modes in achieving local coordination-modulated signal amplifications.Finally,we identify new opportunities and challenges faced by these SACs-based single molecule detections in the further development of biosensors.展开更多
Global concerns have been paid to the potential hazard of traditional herbal medicinal products(THMPs). Substandard and counterfeit THMPs, including traditional Chinese patent medicine, health foods, dietary supplemen...Global concerns have been paid to the potential hazard of traditional herbal medicinal products(THMPs). Substandard and counterfeit THMPs, including traditional Chinese patent medicine, health foods, dietary supplements, etc. are potential threats to public health. Recent marketplace studies using DNA barcoding have determined that the current quality control methods are not sufficient for ensuring the presence of authentic herbal ingredients and detection of contaminants/adulterants. An efficient biomonitoring method for THMPs is of great needed. Herein, metabarcoding and single-molecule, realtime(SMRT) sequencing were used to detect the multiple ingredients in Jiuwei Qianghuo Wan(JWQHW), a classical herbal prescription widely used in China for the last 800 years. Reference experimental mixtures and commercial JWQHW products from the marketplace were used to confirm the method. Successful SMRT sequencing results recovered 5416 and 4342 circular-consensus sequencing(CCS) reads belonging to the ITS2 and psb A-trn H regions. The results suggest that with the combination of metabarcoding and SMRT sequencing, it is repeatable, reliable, and sensitive enough to detect species in the THMPs, and the error in SMRT sequencing did not affect the ability to identify multiple prescribed species and several adulterants/contaminants. It has the potential for becoming a valuable tool for the biomonitoring of multi-ingredient THMPs.展开更多
The Arabidopsis FRA1 kinesin contributes to the organization of cellulose microfibrils through an unknown mechanism. The cortical localization of this kinesin during interphase raises the possibility that it transport...The Arabidopsis FRA1 kinesin contributes to the organization of cellulose microfibrils through an unknown mechanism. The cortical localization of this kinesin during interphase raises the possibility that it transports cell wallrelated cargoes along cortical microtubules that either directly or indirectly influence cellulose microfibril patterning. To determine whether FRA1 is an authentic motor protein, we combined bulk biochemical assays and single molecule fluorescence imaging to analyze the motor properties of recombinant, GFP-tagged FRA1 containing the motor and coiled-coil domains (designated as FRAI(707)-GFP). We found that FRAI(707)-GFP binds to microtubules in an ATP-dependent manner and that its ATPase activity is dramatically stimulated by the presence of microtubules. Using single molecule studies, we found that FRAI(707)-GFP moves processively along microtubule tracks at a velocity of about 0.4 μm s-1. In addition, we found that FRAI(707)-GFP is a microtubule plus-end-directed motor and that it moves along microtubules as a dimer. Interestingly, our single molecule analysis shows that the processivity of FRAI(707)-GFP is at least twice the processivity of conventional kinesin, making FRA1 the most processive kinesin to date. Together, our data show that FRA1 is a bona fide motor protein that has the potential to drive Iong-distance transport of cargo along cortical microtubules.展开更多
The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weightpolytetrafluoroethylene(PTFE)on a substrate as a function of“melt”time and temperature is described.Folded chain singl...The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weightpolytetrafluoroethylene(PTFE)on a substrate as a function of“melt”time and temperature is described.Folded chain singlecrystals parallel to the substrate and as ribbons on-edge(with double striations),as well as bands,are produced for longersintering times;particle merger and diffusion of individual molecules,crystallizing as folded chain,single(or few)molecule,single crystals when“trapped”on the substrate by cooling occur for shorter sintering times.It is suggested the observedstructures develop with sintering time,in a mesomorphic melt.The structure of the nascent particles is also discussed.展开更多
Five novel donor-acceptor (D-A) conjugated cooligomers (F4B-hP, F5B-hP, F5B2[1,2]-hP, F5B2[I,3]-hP and F7B2[1,2]-hP) were synthesized. The absorption spectra of the cooligomers cover a wide range from 300 nm to 63...Five novel donor-acceptor (D-A) conjugated cooligomers (F4B-hP, F5B-hP, F5B2[1,2]-hP, F5B2[I,3]-hP and F7B2[1,2]-hP) were synthesized. The absorption spectra of the cooligomers cover a wide range from 300 nm to 630 nm. The cooligomers could form films featured by alternating D-A lamellar nanostructures with the periods relative to the molecular lengths after thermal annealing or solvent vapor annealing. Single molecule solar cells were fabricated, and FSB-hP exhibited the best device performance. When the film of FSB-hP was thermally annealed, a power conversion efficiency (PCE) of 1.56% was realized. With solvent vapor annealing, the PCE could be further improved to 1.72% with a short-circuit current (J_SC) of 5.76 mA/cm2, an open-circuit voltage (Voc) of 0.87 V and a fill factor (FF) of 0.34.展开更多
Investigation on the folding mode of a single polymer chain in its crystal is significant to the understanding of the mechanism of the fundamental crystallization as well as the engineering of new polymer crystal-base...Investigation on the folding mode of a single polymer chain in its crystal is significant to the understanding of the mechanism of the fundamental crystallization as well as the engineering of new polymer crystal-based materials. Herein, we use the combined techniques of atomic force microscopy (AFM) imaging and force spectroscopy to pull a single polyethylene oxide (PEO) chain out of its spiral crystal in amyl acetate. From these data, the folding mode of polymer chains in the spiral crystal has been reconstructed. We find that the stems tilt in the typical flat area, leading to the decrease in the apparent lamellar height. While in the area of screw dislocation, the lamellar height gradually increases in the range of several nanometers. These results indicate that the combined techniques present a novel tool to directly unravel the chain folding mode of spiral crystals at single-molecule level.展开更多
Significance, difficult, international developing actuality and our completed works for single molecules imaging in living cell with optical method are described respectively. Additionally we give out some suggestions...Significance, difficult, international developing actuality and our completed works for single molecules imaging in living cell with optical method are described respectively. Additionally we give out some suggestions for the technology development further.展开更多
Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, ...Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, a series of metal-organic complexes were synthesized and characterized under the assembly of electron donor phosphonate, electron acceptor polypyridine ligand and spin carrier rare earth ions. All the compounds exhibited remarkable and reversible responses with photochromism and photomodulated fluorescence, originated from photogenerated radicals via electron transfer from phosphonates to polypyridine ligands. For the Dy analog, slow magnetic relaxation was observed at cryogenic temperature, indicating the single-molecule magnetic behavior. Furthermore, photogenerated radicals could enhance the proton conductive behavior, with about 2 times larger in magnitude after light irradiation for Dy and Y compounds. The introduction of photoluminescence, magnetism and proton conduction into metallic phosphonates can provide potential applications for photochromic materials.展开更多
Controlling and manipulating the fluorescence of single fluorophores is of great interest in recent years for its potential uses in improving the performance of molecular photonics and molecular electronics, such as i...Controlling and manipulating the fluorescence of single fluorophores is of great interest in recent years for its potential uses in improving the performance of molecular photonics and molecular electronics, such as in organic light-emitting devices, single photon sources, organic field-effect transistors, and probes or sensors based on single molecules. This review shows how the fluorescence emission of single organic molecules can be modified using local electromagnetic fields of metallic nanostructures and electric-field-induced electron transfer. Electric-field-induced fluorescence modulation, hysteresis, and the achievement of fluorescence switch are discussed in detail.展开更多
To extract the dynamic parameters from single molecule manipulation experiments, usually lots of data at different forces need to be recorded. But the measuring time of a single molecule is limited due to breakage of ...To extract the dynamic parameters from single molecule manipulation experiments, usually lots of data at different forces need to be recorded. But the measuring time of a single molecule is limited due to breakage of the tether or degradation of the molecule. Here we propose a data analysis method based on probability maximizalion of the recorded time trace to extract the dynamic parameters from a single measurement. The feasibility of this method was verified by dealing with the simulation data of a two-state system. We also applied this method to estimate the parameters of DNA hairpin folding and unfolding dynamics measured by a magnetic tweezers experiment.展开更多
In single molecule study,surface-enhanced Raman scattering(SERS)has the advantage of specifically providing structural information of the molecules targeted.The main challenge in single molecule SERS is developing reu...In single molecule study,surface-enhanced Raman scattering(SERS)has the advantage of specifically providing structural information of the molecules targeted.The main challenge in single molecule SERS is developing reusable plasmonic substrates that ensures single molecule sensitivity and acquires intrinsic information of molecules.Here,we proposed a strategy to utilize single-walled carbon nanotubes(SWNTs)to construct SERS substrates.Employing ultrasonic spray pyrolysis,we prepared in situ polyhedral gold nanocrystals closely spaced and attached to nanotubes,ensuring valid hot spots formed along the tube-walls.With such SERS substrates,we proved the single molecule detection by the statistical analysis based on the natural abundance of isotopes.Since SWNTs provide non-chemical bonding adsorption sites,our SERS substrates are easily reusable and have a unique advantage of preserving the intrinsic property of the molecules detected.Using SWNTs to build SERS substrates may become a powerful general strategy in various static and dynamic studies of single molecules.展开更多
Enzymes are the major players for many biological processes.Fundamental studies of the enzymatic activity at the single-molecule level provides important information that is otherwise inaccessible at the ensemble leve...Enzymes are the major players for many biological processes.Fundamental studies of the enzymatic activity at the single-molecule level provides important information that is otherwise inaccessible at the ensemble level.Yet,these single-molecule experiments are technically di±cult and generally require complicated experimental design.Here,we develop a Holliday junction(HJ)-based platform to study the activity of restriction endonucleases at the single-molecule level using single-molecule FRET(sm-FRET).We show that the intrinsic dynamics of HJ can be used as the reporter for both the enzyme-binding and the substrate-release events.Thanks to the multiple-arms structure of HJ,the fluorophore-labeled arms can be different from the surface anchoring arm and the substrate arm.Therefore,it is possible to independently change the substrate arm to study different enzymes with similar functions.Such a design is extremely useful for the systematic study of enzymes from the same family or enzymes bearing different pathologic mutations.Moreover,this method can be easily extended to study other types of DNA-binding enzymes without too much modi fication of the design.We anticipate it can find broad applications in single-molecule enzymology.展开更多
The behavior of a water molecule entering carbon nanotubes (CNTs) is stud- ied. The Lennaxd-Jones potential function together with the continuum approximation is used to obtain the van der Waals interaction between ...The behavior of a water molecule entering carbon nanotubes (CNTs) is stud- ied. The Lennaxd-Jones potential function together with the continuum approximation is used to obtain the van der Waals interaction between a single-walled CNT (SWCNT) and a single water molecule. Three orientations are chosen for the water molecule as the center of mass is on the axis of nanotube. Extensive studies on the variations of force, energy, and velocity distributions axe performed by vaxying the nanotube radius and the orientations of the water molecule. The force and energy distributions are validated by those obtained from molecular dynamics (MD) simulations. The acceptance radius of the nanotube for sucking the water molecule inside is derived, in which the limit of the radius is specified so that the nanotube is favorable to absorb the water molecule. The velocities of a single water molecule entering CNTs axe calculated and the maximum entrance and the interior velocity for different orientations axe assigned and compared.展开更多
基金support from the National Natural Science Foundation of China(No. 20575062) The Graduate Innovation Fund of USTC
文摘We have developed a simple method for fabricating robust and low noise glass nanopore electrodes with pore size 10±5 nm to detect single molecules.β-Cyclodextrin was used as model compound for characterization.In 1.0 mol/L NaCl solution,the molecules generated current pulses of 2-5 pA with noise level less than 0.8 pA.A slide mode and a plug mode were suggested for the way ofβ-cyclodextrin single molecule moving into the glass nanopores.
基金This work is supported by the finical support of the Natural Science Fund(No.52172167)National Key Research and Development Project(No.2021YFE011305)+1 种基金authors also gratefully acknowledge financial support from the Key Research and Development Plan of Anhui Province(No.202104a07020032)Funding Open access funding provided by Shanghai Jiao Tong University
文摘Single-molecule detection and imaging are of great value in chemical analysis,biomarker identification and other trace detection fields.However,the localization and visualization of single molecule are still quite a challenge.Here,we report a special-engineered nanostructure of Ag nanoparticles embedded in multi-layer black phosphorus nanosheets(Ag/BP-NS)synthesized by a unique photoreduction method as a surfaceenhanced Raman scattering(SERS)sensor.Such a SERS substrate features the lowest detection limit of 10^(–20) mol L^(−1) for R6G,which is due to the three synergistic resonance enhancement of molecular resonance,photoinduced charge transfer resonance and electromagnetic resonance.We propose a polarization-mapping strategy to realize the detection and visualization of single molecule.In addition,combined with machine learning,Ag/BP-NS substrates are capable of recognition of different tumor exosomes,which is meaningful for monitoring and early warning of the cancer.This work provides a reliable strategy for the detection of single molecule and a potential candidate for the practical bio-application of SERS technology.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474097,11374099,and 11274116)the Open Fund of the State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)China
文摘This paper reports the plasmonic lasing of a split ring filled with gain material in water. The lasing mode(1500 nm)is far from the pump mode(980 nm), which can depress the detection noise from the pump light. The laser intensities of the two modes simultaneously increase by more than 10^3 in amplitude, which can intensify the absorption efficiency of the pumping light and enhance the plasmonic lasing. The plasmonic lasing is a sensitive sensor. When a single protein nanoparticle(n = 1.5, r = 1.25 nm) is trapped in the gap of the split ring, the lasing spectrum moves by 0.031 nm, which is much larger than the detection limit of 10^-5 nm. Moreover, the lasing intensity is also very sensitive to the trapped nanoparticle. It reduces to less than 1/600 when a protein nanoparticle(n = 1.5, r = 1.25 nm) is trapped in the gap.
基金National Institute of General Medical Sciences of the National Institutes of Health Grant[Grant No.R01GM107165].
文摘The exosome-mediated response can promote or restrain the diseases by regulating the intracellular pathways,making the exosome become an effective marker for diagnosis and therapeutic control at the single-cell level.However,real-time analysis is hard to be achieved with traditional approaches because the exosomes usually need to be enriched by ultracentrifugation for a measurable signal-to-noise ratio.Recently developed label-free single-molecule imaging approaches may become an real-time quantitative tool for the analysis of single exosomes and related secretion behaviors of single living cells owing to their extreme sensitivity.
基金This work was financially supported by the National Natural Science Foundation of China. (No.20271033, 20335020, 90408014).
文摘A single molecule detection technique was developed by the combination of a single channel poly (dimethylsiloxane)/glass micro-fluidic chip and fluorescence correlation spectroscopy (FCS). This method was successfully used to determine the proportion of two model components in the mixture containing fluorescein and the rhodamine-green succinimidyl ester.
文摘The DNA G quadruplex formed by the human telomeric sequence is a potential target for novel anticancer drugs. We have investigated an intramolecular DNA G quadruplex using single molecule fluorescence resonance energy transfer and shown that individual folded quadruplexes can be identified. The mean proximity ratio measured at the single molecule level was consistent with ensemble measurement
基金Prof.Z.Kou acknowledges the financial support of the Fundamental Research Funds for the Central Universities(Grant No.40120631)Natural Science Foundation of Hubei Province(Grant No.2021CFB007)+2 种基金National Natural Science Foundation of China(Grant No.52202291)the support.Prof.J.Wang thanks the support by the Singapore Ministry of Education,and the National Research Foundation(NRF)research conducted at the National University of Singapore(Tier 1,A-8000186-01-00,and CRP NRF-CRP26-2021-0003).
文摘Biosensors featuring single molecule detection present huge opportunities as well as challenges in food safety inspection,disease diagnosis,and environmental monitoring.Single-molecule detection is largely lacking of high enough activity,precision molecule selectivity,and understanding in the exact operating mechanism.Single-atom catalysts(SACs),especially those metals-nitrogen-carbon that mimic the natural metalloenzyme structure,and with well-defined metal atom bond configurations,high level of molecular selectivity,and easy fabrication,endow single molecule detections with practical-use feasibilities.The recent advances in single-atom catalysts also present new pathways in the key mechanism understandings.In this short review,we will first visit the brief history and advantages of SACs that have been explored only recently for molecule-scale biosensors,where they are analogous and also differentiated from those nanozymes and natural metalloenzymes.Their applications in electrochemical,photochemical,and photoelectrochemical sensors are then discussed comprehensively by focusing on the different molecule-scale sensing modes in achieving local coordination-modulated signal amplifications.Finally,we identify new opportunities and challenges faced by these SACs-based single molecule detections in the further development of biosensors.
基金supported by the National Natural Science Foundation of China (Grant No. 81373922)Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Sciences (Grant No. CIFMS, 2016-I2M-3–016)
文摘Global concerns have been paid to the potential hazard of traditional herbal medicinal products(THMPs). Substandard and counterfeit THMPs, including traditional Chinese patent medicine, health foods, dietary supplements, etc. are potential threats to public health. Recent marketplace studies using DNA barcoding have determined that the current quality control methods are not sufficient for ensuring the presence of authentic herbal ingredients and detection of contaminants/adulterants. An efficient biomonitoring method for THMPs is of great needed. Herein, metabarcoding and single-molecule, realtime(SMRT) sequencing were used to detect the multiple ingredients in Jiuwei Qianghuo Wan(JWQHW), a classical herbal prescription widely used in China for the last 800 years. Reference experimental mixtures and commercial JWQHW products from the marketplace were used to confirm the method. Successful SMRT sequencing results recovered 5416 and 4342 circular-consensus sequencing(CCS) reads belonging to the ITS2 and psb A-trn H regions. The results suggest that with the combination of metabarcoding and SMRT sequencing, it is repeatable, reliable, and sensitive enough to detect species in the THMPs, and the error in SMRT sequencing did not affect the ability to identify multiple prescribed species and several adulterants/contaminants. It has the potential for becoming a valuable tool for the biomonitoring of multi-ingredient THMPs.
文摘The Arabidopsis FRA1 kinesin contributes to the organization of cellulose microfibrils through an unknown mechanism. The cortical localization of this kinesin during interphase raises the possibility that it transports cell wallrelated cargoes along cortical microtubules that either directly or indirectly influence cellulose microfibril patterning. To determine whether FRA1 is an authentic motor protein, we combined bulk biochemical assays and single molecule fluorescence imaging to analyze the motor properties of recombinant, GFP-tagged FRA1 containing the motor and coiled-coil domains (designated as FRAI(707)-GFP). We found that FRAI(707)-GFP binds to microtubules in an ATP-dependent manner and that its ATPase activity is dramatically stimulated by the presence of microtubules. Using single molecule studies, we found that FRAI(707)-GFP moves processively along microtubule tracks at a velocity of about 0.4 μm s-1. In addition, we found that FRAI(707)-GFP is a microtubule plus-end-directed motor and that it moves along microtubules as a dimer. Interestingly, our single molecule analysis shows that the processivity of FRAI(707)-GFP is at least twice the processivity of conventional kinesin, making FRA1 the most processive kinesin to date. Together, our data show that FRA1 is a bona fide motor protein that has the potential to drive Iong-distance transport of cargo along cortical microtubules.
文摘The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weightpolytetrafluoroethylene(PTFE)on a substrate as a function of“melt”time and temperature is described.Folded chain singlecrystals parallel to the substrate and as ribbons on-edge(with double striations),as well as bands,are produced for longersintering times;particle merger and diffusion of individual molecules,crystallizing as folded chain,single(or few)molecule,single crystals when“trapped”on the substrate by cooling occur for shorter sintering times.It is suggested the observedstructures develop with sintering time,in a mesomorphic melt.The structure of the nascent particles is also discussed.
基金financially supported by the National Basic Research Program of China(973 Project,No.2009CB939702)of Chinese Ministry of Science and TechnologyNSFC(Nos.20921061 and 50833004)
文摘Five novel donor-acceptor (D-A) conjugated cooligomers (F4B-hP, F5B-hP, F5B2[1,2]-hP, F5B2[I,3]-hP and F7B2[1,2]-hP) were synthesized. The absorption spectra of the cooligomers cover a wide range from 300 nm to 630 nm. The cooligomers could form films featured by alternating D-A lamellar nanostructures with the periods relative to the molecular lengths after thermal annealing or solvent vapor annealing. Single molecule solar cells were fabricated, and FSB-hP exhibited the best device performance. When the film of FSB-hP was thermally annealed, a power conversion efficiency (PCE) of 1.56% was realized. With solvent vapor annealing, the PCE could be further improved to 1.72% with a short-circuit current (J_SC) of 5.76 mA/cm2, an open-circuit voltage (Voc) of 0.87 V and a fill factor (FF) of 0.34.
基金financially supported by the National Natural Science Foundation of China(Nos.20974039,21221063 and 91127031)the National Basic Research Program(2013CB834503)the Program for New Century Excellent Talents in Universities(NCET-11-0205)
文摘Investigation on the folding mode of a single polymer chain in its crystal is significant to the understanding of the mechanism of the fundamental crystallization as well as the engineering of new polymer crystal-based materials. Herein, we use the combined techniques of atomic force microscopy (AFM) imaging and force spectroscopy to pull a single polyethylene oxide (PEO) chain out of its spiral crystal in amyl acetate. From these data, the folding mode of polymer chains in the spiral crystal has been reconstructed. We find that the stems tilt in the typical flat area, leading to the decrease in the apparent lamellar height. While in the area of screw dislocation, the lamellar height gradually increases in the range of several nanometers. These results indicate that the combined techniques present a novel tool to directly unravel the chain folding mode of spiral crystals at single-molecule level.
文摘Significance, difficult, international developing actuality and our completed works for single molecules imaging in living cell with optical method are described respectively. Additionally we give out some suggestions for the technology development further.
基金This work was supported by the State Key Project of Basic Research (973 . Rare earth G1998061320) the Important Foundation of Chinese Academy of Sciences and the National Natural Science Foundation of China ( Grant Nos. 59872042, 69708003).
基金supported by the National Natural Science Foundation of China (Nos. 21901133 and 22071126)Key Research and Development Project of Shandong Province (No. 2019GGX102006)the State Key Laboratory of Fine Chemicals (No. KF1905)。
文摘Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, a series of metal-organic complexes were synthesized and characterized under the assembly of electron donor phosphonate, electron acceptor polypyridine ligand and spin carrier rare earth ions. All the compounds exhibited remarkable and reversible responses with photochromism and photomodulated fluorescence, originated from photogenerated radicals via electron transfer from phosphonates to polypyridine ligands. For the Dy analog, slow magnetic relaxation was observed at cryogenic temperature, indicating the single-molecule magnetic behavior. Furthermore, photogenerated radicals could enhance the proton conductive behavior, with about 2 times larger in magnitude after light irradiation for Dy and Y compounds. The introduction of photoluminescence, magnetism and proton conduction into metallic phosphonates can provide potential applications for photochromic materials.
基金Acknowledgements The project was sponsored by the National Basic Research Program of China (973 Program) (Grant No. 2012CB921603), the National Natural Science Foundation of China (Grant Nos. 61527824, 11434007, 11374196, 11404200, 11504216, and U1510133), PCSIRT (No. IRT13076), and the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province.
文摘Controlling and manipulating the fluorescence of single fluorophores is of great interest in recent years for its potential uses in improving the performance of molecular photonics and molecular electronics, such as in organic light-emitting devices, single photon sources, organic field-effect transistors, and probes or sensors based on single molecules. This review shows how the fluorescence emission of single organic molecules can be modified using local electromagnetic fields of metallic nanostructures and electric-field-induced electron transfer. Electric-field-induced fluorescence modulation, hysteresis, and the achievement of fluorescence switch are discussed in detail.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474237 and 11574310)the 111 Project,China(Grant No.B16029)
文摘To extract the dynamic parameters from single molecule manipulation experiments, usually lots of data at different forces need to be recorded. But the measuring time of a single molecule is limited due to breakage of the tether or degradation of the molecule. Here we propose a data analysis method based on probability maximizalion of the recorded time trace to extract the dynamic parameters from a single measurement. The feasibility of this method was verified by dealing with the simulation data of a two-state system. We also applied this method to estimate the parameters of DNA hairpin folding and unfolding dynamics measured by a magnetic tweezers experiment.
基金supported by the National key R&D Progrom of China(No.2016YFA0201904)the National Natural Science Foundation of China(Nos.21873008 and 21631002)+1 种基金Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXTD-202001)Shenzhen Basic Research Project(No.JCYJ20170817113121505).
文摘In single molecule study,surface-enhanced Raman scattering(SERS)has the advantage of specifically providing structural information of the molecules targeted.The main challenge in single molecule SERS is developing reusable plasmonic substrates that ensures single molecule sensitivity and acquires intrinsic information of molecules.Here,we proposed a strategy to utilize single-walled carbon nanotubes(SWNTs)to construct SERS substrates.Employing ultrasonic spray pyrolysis,we prepared in situ polyhedral gold nanocrystals closely spaced and attached to nanotubes,ensuring valid hot spots formed along the tube-walls.With such SERS substrates,we proved the single molecule detection by the statistical analysis based on the natural abundance of isotopes.Since SWNTs provide non-chemical bonding adsorption sites,our SERS substrates are easily reusable and have a unique advantage of preserving the intrinsic property of the molecules detected.Using SWNTs to build SERS substrates may become a powerful general strategy in various static and dynamic studies of single molecules.
基金The authors greatly appreciate the-nancial support from National Natural Science Foundation of China(Grant Nos.21522402,11674153,11374148,11334004 and 21771103)the Fundamental Research Funds for the Central Universities(Nos.020414380070,020414380050 and 020414380058)Natural Science Foundation of Jiangsu Province(No.BK20160639)and the Shuangchuang Program of Jiangsu Province.
文摘Enzymes are the major players for many biological processes.Fundamental studies of the enzymatic activity at the single-molecule level provides important information that is otherwise inaccessible at the ensemble level.Yet,these single-molecule experiments are technically di±cult and generally require complicated experimental design.Here,we develop a Holliday junction(HJ)-based platform to study the activity of restriction endonucleases at the single-molecule level using single-molecule FRET(sm-FRET).We show that the intrinsic dynamics of HJ can be used as the reporter for both the enzyme-binding and the substrate-release events.Thanks to the multiple-arms structure of HJ,the fluorophore-labeled arms can be different from the surface anchoring arm and the substrate arm.Therefore,it is possible to independently change the substrate arm to study different enzymes with similar functions.Such a design is extremely useful for the systematic study of enzymes from the same family or enzymes bearing different pathologic mutations.Moreover,this method can be easily extended to study other types of DNA-binding enzymes without too much modi fication of the design.We anticipate it can find broad applications in single-molecule enzymology.
文摘The behavior of a water molecule entering carbon nanotubes (CNTs) is stud- ied. The Lennaxd-Jones potential function together with the continuum approximation is used to obtain the van der Waals interaction between a single-walled CNT (SWCNT) and a single water molecule. Three orientations are chosen for the water molecule as the center of mass is on the axis of nanotube. Extensive studies on the variations of force, energy, and velocity distributions axe performed by vaxying the nanotube radius and the orientations of the water molecule. The force and energy distributions are validated by those obtained from molecular dynamics (MD) simulations. The acceptance radius of the nanotube for sucking the water molecule inside is derived, in which the limit of the radius is specified so that the nanotube is favorable to absorb the water molecule. The velocities of a single water molecule entering CNTs axe calculated and the maximum entrance and the interior velocity for different orientations axe assigned and compared.