Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrate...Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrates.Here we present a SM-SERS scheme that involves simultaneously giant chemical enhancement from WS22D materials,giant electromagnetic enhancement from plasmonic nanogap hot spot,and inhibition of molecular fluorescence influence under near-infrared laser illumination.Remarkably we find Coulomb attraction between analyte and gold nanoparticle can trigger spontaneous formation of molecule-hotspot pairing with high precision,stability and robustness.The scheme has enabled realization of universal,robust,fast,and large-scale uniform SM-SERS detection for three Raman molecules of rhodamine B,rhodamine 6G,and crystal violet with a very low detection limit of 10−16 M and at a very fast spectrum acquisition time of 50 ms.展开更多
Sodium alginate(SA)is generally considered highly hydrophilic due to two hydroxyl groups and a carboxylate group on each pyranose ring.However,SA will form a gel after dissolving in water for a certain period.The two ...Sodium alginate(SA)is generally considered highly hydrophilic due to two hydroxyl groups and a carboxylate group on each pyranose ring.However,SA will form a gel after dissolving in water for a certain period.The two properties of SA,hydrophilicity and gelation,seem to be paradoxical.In this study,to explore the mechanism behind these paradoxical properties,the single-chain behaviors of SA in various liquid environments have been investigated by using single-molecule force spectroscopy(SMFS).In nonpolar solvents such as nonane,SA exhibits its single-chain inherent elasticity consistent with the theoretical elasticity derived from quantum mechanical(QM)calculations.Notably,the experimental curve of SA obtained in water shows a long plateau in the low force region.Further research reveals that this phenomenon is driven by the hydrophobic effect.Additionally,SA shows greater rigidity than its inherent elasticity in the middle and high force regions due to electrostatic repulsion between carboxylate groups on adjacent sugar rings.Comparative single-molecule studies suggest that SA exhibits considerable hydrophobicity,offering new insights into the gelation process in water.展开更多
The dynamic regulation of single-molecule magnet(SMM)behavior remains challenging but extremely critical to practical applications.Efficient manipulation of magnetization of complexes via external stimulus,like solven...The dynamic regulation of single-molecule magnet(SMM)behavior remains challenging but extremely critical to practical applications.Efficient manipulation of magnetization of complexes via external stimulus,like solvent,pressure,electric potential or light may further extend the scope of applications for these magnetic molecules.Among these,light is highly desirable because it can provide high-contrast,sensitive and remote control of magnetic behavior at relatively high spatial and temporal resolution.Lanthanide(Ln)complexes represent a distinctive platform for constructing photo-responsive SMMs owing to their extreme sensitivity to subtle change of crystal field(CF)environment.Despite the numerous potential benefits and unique advantages outlined above,light control of magnetism of Ln-SMMs still faces several challenges.This review briefly summarizes recent advancements of photo-responsive Ln-SMMs with photochromic characteristic,highlighting the significance of photoinduced structural changes or electronic distribution alterations to modulate the magnetic properties,which may throw light on the future improvements of photo-responsive molecular materials.展开更多
Transition metal possesses a unique d-orbital electronic structure,which imparts a diverse range of physical and chemical properties.These properties render them significant in fields such as chemistry and materials s...Transition metal possesses a unique d-orbital electronic structure,which imparts a diverse range of physical and chemical properties.These properties render them significant in fields such as chemistry and materials science.The distinctive optical,electrical,and magnetic properties of these complexes can be attributed to the variations in the quantity of d-orbital electrons,thereby influencing their spin and orbital characteristics.The d-orbitals facilitate the formation of stable multidirectional bonds with ligands,resulting in a variety of geometric structures and rich coordination chemistry.These interactions result in variations in energy levels,thereby producing diverse electrical properties,including low attenuation coefficients,high rectification ratios,and unique multichannel transmission.Moreover,the unpaired electrons inthe d-orbitals can give rise to diverse magnetic behaviors,leading to magnetic effects such as spin-related interfaces,switches,and magnetoresistance.This paves the way for extensive possibilities in the design and application of single-molecule devices.This review elaborates on singlemolecule physical properties of transition metal complexes,including length attenuation,rectification,multi-channel transmission,thermoelectric effect,and spin regulation,which are vital for the functionalization and regulation of molecular electronics.In addition,this review also explores the correlation between these physical properties and the electronic structure of transition metals,discussing the broad prospects of transition metal complexes in the fields of nanoelectronics,optoelectronics,and quantum technology.展开更多
Gaining insights into charge transport related to conformational changes and ion transport in valinomycin(VM)is crucial for understanding the underlying physiological processes and advancing ion carrier applications.O...Gaining insights into charge transport related to conformational changes and ion transport in valinomycin(VM)is crucial for understanding the underlying physiological processes and advancing ion carrier applications.Observing these processes in single molecules provides deeper insights and precision than those obtained through conventional ensemble measurements.Herein,we employed a single-molecule conductance measurement method based on the scanning tunneling microscopy break-junction(STM-BJ)to measure the charge transport of individual VM molecules in both non-polar and polar solvents,as well as when mediated by K^(+)ions.Single-molecule conductance measurements revealed that the bracelet and propeller-type conformations of VM in both non-polar and polar solvents significantly affect its conductance.In polar solvents,the propeller-type conformation of VM demonstrated a well-defined conductance signature,single-molecule rectification feature,and through-space transmission mechanism.Specifically,the introduction of K^(+)ions in polar solvents induced a conformational transition from the propeller-type to the bracelet-type form,facilitating K^(+)binding recognition.These observations were further supported by density functional theory combined with non-equilibrium Green’s function calculations.This study enhanced the fundamental understanding of the electronic transport mechanisms in VM and valinomycin-K^(+)molecular junctions,offering insights into VM ionophores and promoting supramolecular sensing applications.展开更多
Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arra...Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arrangement of the intermolecular magnetic dipoles,magnetic blocking can be significantly enhanced.Herein manipulating the intramolecular dipole interactions by ligand modifica-tion was attempted with the use of three closely related dinuclear Er(Ⅲ)complexes of a common chemical formula of[(COT^(R))Er(μ-CI)(THF)]_(2)(COT^(R)is monosubstituted cyclooctatetraenide dianions with R=diphenylmethylsilyl(Ph_(2)MeS)for 1,triethylsilyl(TES)for 2,and triisopropylsilyl(TIPS)for 3).Each of these complexes features a centrosymmetric dinuclear core unit with their component Er(Ⅲ)ions doubly bridged by two chloro ligands and further coordinated with a capping substituted corR ligand and a coordinated THF molecule.Magnetic studies reveal that the complexes display similar ferromagnetic couplings with comparable single-molecule magnetic behaviors.The ferromagnetic couplings dominated by the intramolecular dipole interactions are found to be 0.7614,0.7380,and 0.5635 cm^(-1)for 1,2,and 3,respectively.The angles(θ)between the magnetic easy axes and the intramolecular Er-Er lines are 24.88(2)°,25.23(1),and 31.85(5),leading to transversal dipole fields of 0.0114,0.0113,and 0.0125 T for 1,2,and 3,respectively.Although the different ligand substitution generates a sizable difference of about 7 in theθangle,the resulting difference in the dipole interactions is not sufficiently strong to cause any significant differences in their magnetic properties.Further change in theθangles to the"side-by-side"(θ=90°)or"head-to-tail"(θ=0°)arrangement of the magnetic easy axes,achievable by rational mo-lecular design,is expected to lead to molecular magnetic materials with much enhanced properties.展开更多
DNA imaging and visualization techniques are crucial in biological experiments and have also emerged as a powerful method for single-molecule studies.Traditional intercalating dyes(e.g.,SYTOX,EtBr,GelRed)can stain DNA...DNA imaging and visualization techniques are crucial in biological experiments and have also emerged as a powerful method for single-molecule studies.Traditional intercalating dyes(e.g.,SYTOX,EtBr,GelRed)can stain DNA but may alter its structure and mechanical properties,and cause photocleavage.Recently,a novel fluorescent DNA-binding protein(FP-DBP)was introduced,which can stain DNA without sequence preference and without inducing photocleavage.In this study,using a custom-built magnetic tweezers system,we performed DNA stretching,twisting and unzipping experiments to compare the mechanical properties of DNA with and without two kinds of intercalating dyes(SYTOX Orange and GelRed)and mCherry FP-DBP.Our results show that mCherry FP-DBP does not affect DNA structure or mechanics,unlike SYTOX Orange and GelRed,making FP-DBP a promising tool for DNA visualization in single-molecule experiments.展开更多
Clustering is a pivotal data analysis method for deciphering the charge transport properties of single molecules in break junction experiments.However,given the high dimensionality and variability of the data,feature ...Clustering is a pivotal data analysis method for deciphering the charge transport properties of single molecules in break junction experiments.However,given the high dimensionality and variability of the data,feature extraction remains a bottleneck in the development of efficient clustering methods.In this regard,extensive research over the past two decades has focused on feature engineering and dimensionality reduction in break junction conductance.However,extracting highly relevant features without expert knowledge remains an unresolved challenge.To address this issue,we propose a deep clustering method driven by task-oriented representation learning(CTRL)in which the clustering module serves as a guide for the representation learning(RepL)module.First,we determine an optimal autoencoder(AE)structure through a neural architecture search(NAS)to ensure efficient RepL;second,the RepL process is guided by a joint training strategy that combines AE reconstruction loss with the clustering objective.The results demonstrate that CTRL achieves excellent performance on both the generated and experimental data.Further inspection of the RepL step reveals that joint training robustly learns more compact features than the unconstrained AE or traditional dimensionality reduction methods,significantly reducing misclustering possibilities.Our method provides a general end-to-end automatic clustering solution for analyzing single-molecule break junction data.展开更多
The forming processes of 4,40-dipyridyl-based single-molecule junctions and mechanically induced conductance switching as well as the side-group effects are systematically investigated by applying the ab initio-based ...The forming processes of 4,40-dipyridyl-based single-molecule junctions and mechanically induced conductance switching as well as the side-group effects are systematically investigated by applying the ab initio-based adiabatic geometric optimization method and the one-dimensional transmission combined with three-dimensional correction approximation(OTCTCA)method.The numerical results show that for the 4,40-dipyridyl with a p-conjugated phenyl-phosphoryl or diphenylsilyl side group,the pyridyl vertically anchors on the second atomic layer of the pyramid-shaped Au tip electrode at small inter-electrode distances by laterally pushing the apical Au atom aside,which induces stronger pyridyl-electrode coupling and high-conductance state of the formed junctions.As the inter-electrode distance increases,the pyridyl shifts to the apical Au atom of the tip electrode.This apical Au atom introduces additional scatterings to the tunneling electrons and significantly decreases the conductance of the junctions.Furthermore,for the 4,40-dipyridyl with a phenyl-phosphoryl side group,the probability of manifesting the high-conductance state is decreased due to the oxygen atom reducing the probability of the pyridyl adsorbing on the second layer of Au tip electrode.In contrast,for the 4,40-dipyridyl with a nonconjugated cyclohexyl-phosphoryl side group,the steric hindrance from the bulky cyclohexyl group leads the molecule to preferentially form the O-Au contact,which prevents both the high conductance and mechanically induced conductance switching of the junction.Our results provide a theoretical understanding of the side-group effects on electronic transport properties of single-molecule junctions,offering an alternative explanation for the experimental observations.展开更多
The electronic structure of semiconductor materials governs the law of electron motion,which profoundly affects the properties such as conductivity and photoelectric conversion.Photo-responsive single-molecule junctio...The electronic structure of semiconductor materials governs the law of electron motion,which profoundly affects the properties such as conductivity and photoelectric conversion.Photo-responsive single-molecule junction technology provides insights into the electronic structure of photogenerated substances at the molecular scale,enabling the characterization of dynamic processes such as charge separation and energy transfer.These processes involve the unique quantum state known as the "exciton".The electrical characterization technique based on single molecule break junction facilities direct measurement of the photoelectric response of molecules at nanometer and subnanometer scale.This study reviews recent research progress of exciton effects and the characterization of optoelectronic phenomena.The mechanisms of exciton effects in three key optoelectronic phenomena—photoconductivity,photovoltaic s,and photoluminescence—are discussed.Furthermore,advanced spectral characterization techniques applied to the in-situ monitoring of single-molecule optoelectronic devices are highlighted.These include Raman spectroscopy with various enhancements,inelastic electron tunneling spectroscopy,and ultrafast spectroscopy with high resolution.展开更多
Quinoid structures are considered to be conducive to the charge transport of organic molecules,but this hypothesis is rarely proven at single-molecule level.Herein,as a proof of concept,the single-molecule conductance...Quinoid structures are considered to be conducive to the charge transport of organic molecules,but this hypothesis is rarely proven at single-molecule level.Herein,as a proof of concept,the single-molecule conductance of two furan-based isomers,3,3'-bis(4-(methylthio)phenyl)-2,2'-bifuran(2,2'-SMPBF)and 4,4'-bis(4-(methylthio)phenyl)-3,3'-bifuran(3,3'-SMPBF),is investigated by the scanning tunneling microscopy break junction(STM-BJ)technique and theoretical simulation.2,2'-SMPBF prefers to adopt a nearly planar conformation with intact alternating single and double bonds extended via2,2'-bifuran moiety and therefore exhibits goodπ-conjugation and a prominent quinoid structure.However,theπ-conjugation of 3,3'-SMPBF is interrupted due to ineffective cross-conjugation in the 3,3'-bifuran moiety,leading to the absence of a quinoid structure.2,2'-SMPBF displays switchable multiple conductances induced by the interconversion between folded and unfolded conformations and an abnormal rebound of conductance along with the increases of electrode displacement,which is demonstrated to be caused by the quinoid structure in a nearly planar conformation during the stretching process.However,3,3'-SMPBF without a quinoid structure in unfolded conformation exhibits extremely low conductance that cannot be captured in STM-BJ measurements.These results reveal the significant contribution of quinoid structure to molecular charge transport and provide valuable information on the structure-transport relationship for the design of efficient organic semiconductors.展开更多
Due to the ionic feature of the lanthanide ions,to straightly bridge two lanthanide(Ln)ions is rather challenging though this bridging mode is much beneficial to suppress the zero-field quantum tunneling of the magnet...Due to the ionic feature of the lanthanide ions,to straightly bridge two lanthanide(Ln)ions is rather challenging though this bridging mode is much beneficial to suppress the zero-field quantum tunneling of the magnetization(QTM)for single-molecule magnets(SMMs),a kind of nanosized magnetic materials for high-density information storage and magnetic resonance imaging contrast agent.Here we used an unusual terminal amino pyridine ligand which utilizes extensive supramolecular interactions to stabilize such an unusual linear bridging mode and obtained a series of such dimeric Ln(Ⅲ)complexes-{[LnL_(A)(4-NH_(2)py)_(5)]_(2)(μ-Cl)}[BPh_(4)]_(3)(For L_(A)^(-)=1-AdO^(-),1Ln;for L_(A)^(-)=~tBuO^(-),2Ln;Ln=Dy,Gd).More uniquely,the bridging chloride sits in the center of two improper rotation symmetry related Ln(Ⅲ)ions with local C_(5v)symmetry.The dimeric compounds 1Dy and 2Dy exhibit much slower low-temperature magnetic relaxation and thousands of times longer relaxation times at 2 K(τ_(2K)=2706.89 and 1437.05 s for 1Dy and 2Dy)compared to the diluted ones with the approaching magnetic property of the C_(5v)motifs(τ_(2K)=0.77 and 1.29 s for 1Dy@1Y and 2Dy@2Y).Though magnetic interactions mediated via the chloride bridge in both 1Dy and 2Dy are weak and antiferromagnetic,it is still very effective due to such a linear geometry to reduce the QTM effect in SMMs.展开更多
Despite the ongoing increase in the efficiency of perovskite solar cells(PSCs),residual lead iodide(PbI2and moisture sensitivity issues continue to constrain their further commercialization.Herein,we propose a thermal...Despite the ongoing increase in the efficiency of perovskite solar cells(PSCs),residual lead iodide(PbI2and moisture sensitivity issues continue to constrain their further commercialization.Herein,we propose a thermally mediated in situ repair and encapsulation strategy to construct high-performance PSCs by incorporating piperazine thioctic acid salt(TAPPZ)as a dopant into the perovskite precursor Thermally dissociated piperazine(PPZ)from TAPPZ integrates microcrystals to form larger grain(>2000 nm),while the carboxylic acid in thioctic acid(TA)and the amine salt in TAPPZ synergistically passivate and transform PbI_(2),significantly reducing its residual amount.Additionally,TAPPZ undergoe thermal self-crosslinking during perovskite annealing,enabling melt-polymerization to form in situ encapsulation for enhanced water resistance.The TAPPZ-incorporated device achieves a remarkable efficiency of 25.65% and exhibits excellent operational stability,retaining over 90% of its initial efficiency after 2000 h under ambient conditions(20-30℃,20%-30% relative humidity).This study provide new insights into the construction of high-performance perovskite solar cells by designing and synthe sizing multifunctional single molecules for in situ repair and encapsulation of perovskites.展开更多
The design and synthesis of a novel π-conjugated fiuorescent framework by external ligand-assisted C-H olefination of heterocycles with excellent regioselectivity and broad substrate scope are reported herein.These n...The design and synthesis of a novel π-conjugated fiuorescent framework by external ligand-assisted C-H olefination of heterocycles with excellent regioselectivity and broad substrate scope are reported herein.These novel fiuorescent materials could present full-color-tunable emissions with large Stokes shifts. Furthermore, the protocol provides an opportunity to rapidly screen novel organic single-molecule whitelight materials with high fiuorescence quantum yields. The robust organic and low-cost white lightemitting diodes could rapidly be fabricated using the white-light-emitting material. Experimental data and theoretical calculations indicate that in the white-light dual emission the relatively short wavelength from high-lying singlet state emission and the relatively long wavelength from low-lying singlet state emission. The anti-Kasha dual-emission systems will provide a foundation for the development and application of organic single-molecule white light materials, effectively promoting the development and innovation of luminescent materials. In addition, this method demonstrated its potential application in the synthesis of new near-infrared(NIR) fiuorescence materials with large Stokes shifts based on the olefination of heterocycles.展开更多
Using exact diagonalization of the Hamiltonian and transition matrix in the energy eigenbasis,we perform model calculations of the magnetic relaxation rate in single-molecule magnets.A careful examination of the trans...Using exact diagonalization of the Hamiltonian and transition matrix in the energy eigenbasis,we perform model calculations of the magnetic relaxation rate in single-molecule magnets.A careful examination of the transition matrix reveals that resonant tunneling does not enhance transitions between the nearly degenerate states;rather,it suppresses them.Instead,transitions from one state in the degenerate pair to neighboring states of the other are significantly enhanced.We conduct a detailed analysis of the transition rates to clearly demonstrate how resonant tunneling modulates these processes.This work provides a substantial reinterpretation of the resonant magnetic relaxation in single-molecule magnets and clearly identifies the dominant relaxation pathways.展开更多
The single-molecule detection tech-nique plays a pivotal role in elucidat-ing the fundamental mechanisms of various scientific processes at the molecular level,and holds essential im-portance in multiple fields includ...The single-molecule detection tech-nique plays a pivotal role in elucidat-ing the fundamental mechanisms of various scientific processes at the molecular level,and holds essential im-portance in multiple fields including physics,biology,and chemistry.Re-cently,single-molecule detection has garnered increasing attention owing to its practical utility in medical diagno-sis,primarily due to its exceptional sensitivity and the minimal sample volume required for analysis.However,the conventional single-molecule technique,represented by total internal reflection microscopy,faces challenges such as sophisticated operation procedures and limited detection throughput,thereby impeding its broader application.To address these limitations,we have demonstrated single-molecule detection using an integrated silicon photonic chip,of-fering a cost-effective and user-friendly alternative.By employing basic optics,we efficiently introduce the excitation source for single-molecule fluorescence by harnessing the strong evanescent field of high refractive-index waveguides.Subsequently,fluorescence signals are collected using basic optics comprising a water-immersion objective,relay optics,and a digi-tal camera.Our results highlight a low-cost,high-throughput single-molecule technique achieved through the integrated silicon photonic chip.This innovative approach is promised to facilitate the widespread adoption of single-molecule fluorescence in medical diagnosis.展开更多
Physical biology is an interdisciplinary field that bridges biology with physical sciences and engineering.Singlemolecule physical biology focuses on dynamics of individual biomolecules and complexes,aiming to answeri...Physical biology is an interdisciplinary field that bridges biology with physical sciences and engineering.Singlemolecule physical biology focuses on dynamics of individual biomolecules and complexes,aiming to answering basic questions about their functions and mechanisms.It takes advantages of physical methodologies to gain quantitative understanding of biological processes,often engaging precise physical measurements of reconstructed objects to avoid interference from unnecessary complications.In this review,we(i)briefly introduce concepts of single-molecule physical biology,(ii)describe extensively used single-molecule methodologies that have been developed to address key questions in two important objects of single-molecule physical biology,namely,nucleic acid-interacting proteins and membraneinteracting proteins,and(iii)show by a few successful examples how one may use single-molecule methods to deepen our understanding of protein machines.展开更多
Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the ...Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the weak nature of H-bonds.Vacuum-based singlemolecule force spectroscopy(Vac-SMFS)offers a new and precise approach for such measurements.Using polyallylamine(PAAm)as a model polymer,the intrinsic strength(i.e.,strength without external influences)of representative N―H…N H-bonds was quantified to be about 5.25 kJ·mol^(–1).Comparative Vac-SMFS analysis across different polymer systems revealed that the N―H…N H-bonds in PAAm are unexpectedly stronger than the N―H…O H-bonds in poly(N-isopropylacrylamide)(PNIPAM)and the O―H…O H-bonds in poly(hydroxyethyl methacrylate)(PHEMA).This trend contrasts with that of established small-molecule systems.These results highlight how side-chain length and spatial configuration dictate polymer H-bond strengths,expanding the fundamental knowledge of polymer interactions and enabling the rational design of next-generation functional materials.展开更多
Transforming growth factor-β （TGF-β） binds with two transmembrane serine/threonine kinase receptors, type Ⅱ （TβRII） and type Ⅰ receptors （TβRⅠ）, and one accessory receptor, type Ⅲ receptor （TβRⅢ）, to...Transforming growth factor-β （TGF-β） binds with two transmembrane serine/threonine kinase receptors, type Ⅱ （TβRII） and type Ⅰ receptors （TβRⅠ）, and one accessory receptor, type Ⅲ receptor （TβRⅢ）, to transduce signals across cell membranes. Previous biochemical studies suggested that TβRI and TβRIII are preexisted homo-dimers. Using single-molecule microscopy to image green fluorescent protein-labeled membrane proteins, for the first time we have demonstrated that TβRI and TβRⅢ could exist as monomers at a low expression level. Upon TGF-β1 stimu- lation, TβRI follows the general ligand-induced receptor dimerization model for activation, but this process is TβRⅡ- dependent. The monomeric status of the non-kinase receptor TβRⅢ is unchanged in the presence of TGF-β1. With the increase of receptor expression, both TβRI and TβRIII can be assembled into dimers on cell surfaces.展开更多
Single-molecule devices not only promise to provide an alternative strategy to break through the miniaturization and functionalization bottlenecks faced by traditional semiconductor devices,but also provide a reliable...Single-molecule devices not only promise to provide an alternative strategy to break through the miniaturization and functionalization bottlenecks faced by traditional semiconductor devices,but also provide a reliable platform for exploration of the intrinsic properties of matters at the single-molecule level.Because the regulation of the electrical properties of single-molecule devices will be a key factor in enabling further advances in the development of molecular electronics,it is necessary to clarify the interactions between the charge transport occurring in the device and the external fields,particularly the optical field.This review mainly introduces the optoelectronic effects that are involved in single-molecule devices,including photoisomerization switching,photoconductance,plasmon-induced excitation,photovoltaic effect,and electroluminescence.We also summarize the optoelectronic mechanisms of single-molecule devices,with particular emphasis on the photoisomerization,photoexcitation,and photo-assisted tunneling processes.Finally,we focus the discussion on the opportunities and challenges arising in the single-molecule optoelectronics field and propose further possible breakthroughs.展开更多
基金financial support from Science and Technology Project of Guangdong(2020B010190001)National Natural Science Foundation(12434016).
文摘Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrates.Here we present a SM-SERS scheme that involves simultaneously giant chemical enhancement from WS22D materials,giant electromagnetic enhancement from plasmonic nanogap hot spot,and inhibition of molecular fluorescence influence under near-infrared laser illumination.Remarkably we find Coulomb attraction between analyte and gold nanoparticle can trigger spontaneous formation of molecule-hotspot pairing with high precision,stability and robustness.The scheme has enabled realization of universal,robust,fast,and large-scale uniform SM-SERS detection for three Raman molecules of rhodamine B,rhodamine 6G,and crystal violet with a very low detection limit of 10−16 M and at a very fast spectrum acquisition time of 50 ms.
基金financially supported by the National Natural Science Foundation of China(No.22273079)。
文摘Sodium alginate(SA)is generally considered highly hydrophilic due to two hydroxyl groups and a carboxylate group on each pyranose ring.However,SA will form a gel after dissolving in water for a certain period.The two properties of SA,hydrophilicity and gelation,seem to be paradoxical.In this study,to explore the mechanism behind these paradoxical properties,the single-chain behaviors of SA in various liquid environments have been investigated by using single-molecule force spectroscopy(SMFS).In nonpolar solvents such as nonane,SA exhibits its single-chain inherent elasticity consistent with the theoretical elasticity derived from quantum mechanical(QM)calculations.Notably,the experimental curve of SA obtained in water shows a long plateau in the low force region.Further research reveals that this phenomenon is driven by the hydrophobic effect.Additionally,SA shows greater rigidity than its inherent elasticity in the middle and high force regions due to electrostatic repulsion between carboxylate groups on adjacent sugar rings.Comparative single-molecule studies suggest that SA exhibits considerable hydrophobicity,offering new insights into the gelation process in water.
基金financially supported by the Fundamental Research Program of Shanxi Province(No.202303021222126)the National Natural Science Foundation of China(No.92261103)。
文摘The dynamic regulation of single-molecule magnet(SMM)behavior remains challenging but extremely critical to practical applications.Efficient manipulation of magnetization of complexes via external stimulus,like solvent,pressure,electric potential or light may further extend the scope of applications for these magnetic molecules.Among these,light is highly desirable because it can provide high-contrast,sensitive and remote control of magnetic behavior at relatively high spatial and temporal resolution.Lanthanide(Ln)complexes represent a distinctive platform for constructing photo-responsive SMMs owing to their extreme sensitivity to subtle change of crystal field(CF)environment.Despite the numerous potential benefits and unique advantages outlined above,light control of magnetism of Ln-SMMs still faces several challenges.This review briefly summarizes recent advancements of photo-responsive Ln-SMMs with photochromic characteristic,highlighting the significance of photoinduced structural changes or electronic distribution alterations to modulate the magnetic properties,which may throw light on the future improvements of photo-responsive molecular materials.
基金financially supported by the National Key R&D Program of China(Nos.2021YFA1200102,2021YFA1200101,2023YFF1205803,2022YFE0128700)the National Natural Science Foundation of China(Nos.22173050,22150013,21727806,21933001)+1 种基金Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-202407)the Natural Science Foundation of Beijing(No.2222009)
文摘Transition metal possesses a unique d-orbital electronic structure,which imparts a diverse range of physical and chemical properties.These properties render them significant in fields such as chemistry and materials science.The distinctive optical,electrical,and magnetic properties of these complexes can be attributed to the variations in the quantity of d-orbital electrons,thereby influencing their spin and orbital characteristics.The d-orbitals facilitate the formation of stable multidirectional bonds with ligands,resulting in a variety of geometric structures and rich coordination chemistry.These interactions result in variations in energy levels,thereby producing diverse electrical properties,including low attenuation coefficients,high rectification ratios,and unique multichannel transmission.Moreover,the unpaired electrons inthe d-orbitals can give rise to diverse magnetic behaviors,leading to magnetic effects such as spin-related interfaces,switches,and magnetoresistance.This paves the way for extensive possibilities in the design and application of single-molecule devices.This review elaborates on singlemolecule physical properties of transition metal complexes,including length attenuation,rectification,multi-channel transmission,thermoelectric effect,and spin regulation,which are vital for the functionalization and regulation of molecular electronics.In addition,this review also explores the correlation between these physical properties and the electronic structure of transition metals,discussing the broad prospects of transition metal complexes in the fields of nanoelectronics,optoelectronics,and quantum technology.
基金supported by the National Key R&D Program of China(Nos.2022YFB3204402,2020YFA0714703 and 2022YFC2205003)the National Natural Science Foundation of China(No.22204135)+2 种基金Hunan Provincial Natural Science Foundation of China(No.2023JJ40619)the Education Department of Hunan Province(No.23A0114)the Science and Technology Innovation Program of Hunan Province(No.2022RC3027)。
文摘Gaining insights into charge transport related to conformational changes and ion transport in valinomycin(VM)is crucial for understanding the underlying physiological processes and advancing ion carrier applications.Observing these processes in single molecules provides deeper insights and precision than those obtained through conventional ensemble measurements.Herein,we employed a single-molecule conductance measurement method based on the scanning tunneling microscopy break-junction(STM-BJ)to measure the charge transport of individual VM molecules in both non-polar and polar solvents,as well as when mediated by K^(+)ions.Single-molecule conductance measurements revealed that the bracelet and propeller-type conformations of VM in both non-polar and polar solvents significantly affect its conductance.In polar solvents,the propeller-type conformation of VM demonstrated a well-defined conductance signature,single-molecule rectification feature,and through-space transmission mechanism.Specifically,the introduction of K^(+)ions in polar solvents induced a conformational transition from the propeller-type to the bracelet-type form,facilitating K^(+)binding recognition.These observations were further supported by density functional theory combined with non-equilibrium Green’s function calculations.This study enhanced the fundamental understanding of the electronic transport mechanisms in VM and valinomycin-K^(+)molecular junctions,offering insights into VM ionophores and promoting supramolecular sensing applications.
基金the National Natural Science Foundation of China(92261203,22101116,21971106)the Science Research Foun dation of jilin Province(YDZJ202301ZYTS478)。
文摘Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arrangement of the intermolecular magnetic dipoles,magnetic blocking can be significantly enhanced.Herein manipulating the intramolecular dipole interactions by ligand modifica-tion was attempted with the use of three closely related dinuclear Er(Ⅲ)complexes of a common chemical formula of[(COT^(R))Er(μ-CI)(THF)]_(2)(COT^(R)is monosubstituted cyclooctatetraenide dianions with R=diphenylmethylsilyl(Ph_(2)MeS)for 1,triethylsilyl(TES)for 2,and triisopropylsilyl(TIPS)for 3).Each of these complexes features a centrosymmetric dinuclear core unit with their component Er(Ⅲ)ions doubly bridged by two chloro ligands and further coordinated with a capping substituted corR ligand and a coordinated THF molecule.Magnetic studies reveal that the complexes display similar ferromagnetic couplings with comparable single-molecule magnetic behaviors.The ferromagnetic couplings dominated by the intramolecular dipole interactions are found to be 0.7614,0.7380,and 0.5635 cm^(-1)for 1,2,and 3,respectively.The angles(θ)between the magnetic easy axes and the intramolecular Er-Er lines are 24.88(2)°,25.23(1),and 31.85(5),leading to transversal dipole fields of 0.0114,0.0113,and 0.0125 T for 1,2,and 3,respectively.Although the different ligand substitution generates a sizable difference of about 7 in theθangle,the resulting difference in the dipole interactions is not sufficiently strong to cause any significant differences in their magnetic properties.Further change in theθangles to the"side-by-side"(θ=90°)or"head-to-tail"(θ=0°)arrangement of the magnetic easy axes,achievable by rational mo-lecular design,is expected to lead to molecular magnetic materials with much enhanced properties.
基金supported by the National Natural Science Foundation of China(Grant No.32371284)the Open Fund of the State Key Laboratory of Optoelectronic Materials and Technologies,Sun Yatsen University(Grant No.OEMT-2024-ZTS-04)support from the Physical Research Platform in the School of Physics,Sun Yatsen University(Grant No.PRPSP,SYSU).
文摘DNA imaging and visualization techniques are crucial in biological experiments and have also emerged as a powerful method for single-molecule studies.Traditional intercalating dyes(e.g.,SYTOX,EtBr,GelRed)can stain DNA but may alter its structure and mechanical properties,and cause photocleavage.Recently,a novel fluorescent DNA-binding protein(FP-DBP)was introduced,which can stain DNA without sequence preference and without inducing photocleavage.In this study,using a custom-built magnetic tweezers system,we performed DNA stretching,twisting and unzipping experiments to compare the mechanical properties of DNA with and without two kinds of intercalating dyes(SYTOX Orange and GelRed)and mCherry FP-DBP.Our results show that mCherry FP-DBP does not affect DNA structure or mechanics,unlike SYTOX Orange and GelRed,making FP-DBP a promising tool for DNA visualization in single-molecule experiments.
基金supported by Guangxi Science and Technology Program(No.GuiKeAD23026291)Guangxi Science and Technology Major Project(No.AA22068057).
文摘Clustering is a pivotal data analysis method for deciphering the charge transport properties of single molecules in break junction experiments.However,given the high dimensionality and variability of the data,feature extraction remains a bottleneck in the development of efficient clustering methods.In this regard,extensive research over the past two decades has focused on feature engineering and dimensionality reduction in break junction conductance.However,extracting highly relevant features without expert knowledge remains an unresolved challenge.To address this issue,we propose a deep clustering method driven by task-oriented representation learning(CTRL)in which the clustering module serves as a guide for the representation learning(RepL)module.First,we determine an optimal autoencoder(AE)structure through a neural architecture search(NAS)to ensure efficient RepL;second,the RepL process is guided by a joint training strategy that combines AE reconstruction loss with the clustering objective.The results demonstrate that CTRL achieves excellent performance on both the generated and experimental data.Further inspection of the RepL step reveals that joint training robustly learns more compact features than the unconstrained AE or traditional dimensionality reduction methods,significantly reducing misclustering possibilities.Our method provides a general end-to-end automatic clustering solution for analyzing single-molecule break junction data.
基金supported by the National Natural Science Foundation of China(Grant Nos.12474286,22173052,and 12204281).
文摘The forming processes of 4,40-dipyridyl-based single-molecule junctions and mechanically induced conductance switching as well as the side-group effects are systematically investigated by applying the ab initio-based adiabatic geometric optimization method and the one-dimensional transmission combined with three-dimensional correction approximation(OTCTCA)method.The numerical results show that for the 4,40-dipyridyl with a p-conjugated phenyl-phosphoryl or diphenylsilyl side group,the pyridyl vertically anchors on the second atomic layer of the pyramid-shaped Au tip electrode at small inter-electrode distances by laterally pushing the apical Au atom aside,which induces stronger pyridyl-electrode coupling and high-conductance state of the formed junctions.As the inter-electrode distance increases,the pyridyl shifts to the apical Au atom of the tip electrode.This apical Au atom introduces additional scatterings to the tunneling electrons and significantly decreases the conductance of the junctions.Furthermore,for the 4,40-dipyridyl with a phenyl-phosphoryl side group,the probability of manifesting the high-conductance state is decreased due to the oxygen atom reducing the probability of the pyridyl adsorbing on the second layer of Au tip electrode.In contrast,for the 4,40-dipyridyl with a nonconjugated cyclohexyl-phosphoryl side group,the steric hindrance from the bulky cyclohexyl group leads the molecule to preferentially form the O-Au contact,which prevents both the high conductance and mechanically induced conductance switching of the junction.Our results provide a theoretical understanding of the side-group effects on electronic transport properties of single-molecule junctions,offering an alternative explanation for the experimental observations.
基金financially supported by the Program of Higher-Level Talents of IMU(No.21300-5223748)the National Natural Science Foundation of China(Nos.22103065 and 21661024)
文摘The electronic structure of semiconductor materials governs the law of electron motion,which profoundly affects the properties such as conductivity and photoelectric conversion.Photo-responsive single-molecule junction technology provides insights into the electronic structure of photogenerated substances at the molecular scale,enabling the characterization of dynamic processes such as charge separation and energy transfer.These processes involve the unique quantum state known as the "exciton".The electrical characterization technique based on single molecule break junction facilities direct measurement of the photoelectric response of molecules at nanometer and subnanometer scale.This study reviews recent research progress of exciton effects and the characterization of optoelectronic phenomena.The mechanisms of exciton effects in three key optoelectronic phenomena—photoconductivity,photovoltaic s,and photoluminescence—are discussed.Furthermore,advanced spectral characterization techniques applied to the in-situ monitoring of single-molecule optoelectronic devices are highlighted.These include Raman spectroscopy with various enhancements,inelastic electron tunneling spectroscopy,and ultrafast spectroscopy with high resolution.
基金financially supported by the National Natural Science Foundation of China(Nos.U23A20594,22375066 and 21788102)Guang Dong Basic and Applied Basic Research Foundation(No.2023B1515040003)。
文摘Quinoid structures are considered to be conducive to the charge transport of organic molecules,but this hypothesis is rarely proven at single-molecule level.Herein,as a proof of concept,the single-molecule conductance of two furan-based isomers,3,3'-bis(4-(methylthio)phenyl)-2,2'-bifuran(2,2'-SMPBF)and 4,4'-bis(4-(methylthio)phenyl)-3,3'-bifuran(3,3'-SMPBF),is investigated by the scanning tunneling microscopy break junction(STM-BJ)technique and theoretical simulation.2,2'-SMPBF prefers to adopt a nearly planar conformation with intact alternating single and double bonds extended via2,2'-bifuran moiety and therefore exhibits goodπ-conjugation and a prominent quinoid structure.However,theπ-conjugation of 3,3'-SMPBF is interrupted due to ineffective cross-conjugation in the 3,3'-bifuran moiety,leading to the absence of a quinoid structure.2,2'-SMPBF displays switchable multiple conductances induced by the interconversion between folded and unfolded conformations and an abnormal rebound of conductance along with the increases of electrode displacement,which is demonstrated to be caused by the quinoid structure in a nearly planar conformation during the stretching process.However,3,3'-SMPBF without a quinoid structure in unfolded conformation exhibits extremely low conductance that cannot be captured in STM-BJ measurements.These results reveal the significant contribution of quinoid structure to molecular charge transport and provide valuable information on the structure-transport relationship for the design of efficient organic semiconductors.
基金supported by the National Natural Science Foundation of China(No.22375157)the State Key Laboratory of Electrical Insulation and Power Equipment(No.EIPE23405)+2 种基金the Fundamental Research Funds for Central Universities(No.xtr052023002)the Special Support Plan of Shaanxi Province for Young Top-notch Talentthe Medical-Engineering Cross Project of the First Affiliated Hospital of XJTU(No.QYJC02)。
文摘Due to the ionic feature of the lanthanide ions,to straightly bridge two lanthanide(Ln)ions is rather challenging though this bridging mode is much beneficial to suppress the zero-field quantum tunneling of the magnetization(QTM)for single-molecule magnets(SMMs),a kind of nanosized magnetic materials for high-density information storage and magnetic resonance imaging contrast agent.Here we used an unusual terminal amino pyridine ligand which utilizes extensive supramolecular interactions to stabilize such an unusual linear bridging mode and obtained a series of such dimeric Ln(Ⅲ)complexes-{[LnL_(A)(4-NH_(2)py)_(5)]_(2)(μ-Cl)}[BPh_(4)]_(3)(For L_(A)^(-)=1-AdO^(-),1Ln;for L_(A)^(-)=~tBuO^(-),2Ln;Ln=Dy,Gd).More uniquely,the bridging chloride sits in the center of two improper rotation symmetry related Ln(Ⅲ)ions with local C_(5v)symmetry.The dimeric compounds 1Dy and 2Dy exhibit much slower low-temperature magnetic relaxation and thousands of times longer relaxation times at 2 K(τ_(2K)=2706.89 and 1437.05 s for 1Dy and 2Dy)compared to the diluted ones with the approaching magnetic property of the C_(5v)motifs(τ_(2K)=0.77 and 1.29 s for 1Dy@1Y and 2Dy@2Y).Though magnetic interactions mediated via the chloride bridge in both 1Dy and 2Dy are weak and antiferromagnetic,it is still very effective due to such a linear geometry to reduce the QTM effect in SMMs.
基金supported by the National Natural Science Foundation of China(22238002 and 22208047)the China Postdoctoral Science Foundation(2024T170086 and 2022M720639)+1 种基金the Research and Innovation Team Project of Dalian University of Technology(DUT2022TB10)the Fundamental Research Funds for the Central Universities(DUT22LAB610)。
文摘Despite the ongoing increase in the efficiency of perovskite solar cells(PSCs),residual lead iodide(PbI2and moisture sensitivity issues continue to constrain their further commercialization.Herein,we propose a thermally mediated in situ repair and encapsulation strategy to construct high-performance PSCs by incorporating piperazine thioctic acid salt(TAPPZ)as a dopant into the perovskite precursor Thermally dissociated piperazine(PPZ)from TAPPZ integrates microcrystals to form larger grain(>2000 nm),while the carboxylic acid in thioctic acid(TA)and the amine salt in TAPPZ synergistically passivate and transform PbI_(2),significantly reducing its residual amount.Additionally,TAPPZ undergoe thermal self-crosslinking during perovskite annealing,enabling melt-polymerization to form in situ encapsulation for enhanced water resistance.The TAPPZ-incorporated device achieves a remarkable efficiency of 25.65% and exhibits excellent operational stability,retaining over 90% of its initial efficiency after 2000 h under ambient conditions(20-30℃,20%-30% relative humidity).This study provide new insights into the construction of high-performance perovskite solar cells by designing and synthe sizing multifunctional single molecules for in situ repair and encapsulation of perovskites.
基金the Fundamental Research Funds for the Central Universities (Nos. 2024CDJXY0022023CDJYGRH-YB17+4 种基金2022CDJXY-025)the Venture & Innovation Support Program for Chongqing Overseas Returnees (No. cx2022061)the Natural Science Foundation of Chongqing (No. CSTB2022NSCQ-MSX1123)the Chongqing Talents: Exceptional Young Talents Project (No. cstc2021ycjh-bgzxm0067)the Hongshen Young Scholars Program from Chongqing University (No. 0247001104426) for financial support。
文摘The design and synthesis of a novel π-conjugated fiuorescent framework by external ligand-assisted C-H olefination of heterocycles with excellent regioselectivity and broad substrate scope are reported herein.These novel fiuorescent materials could present full-color-tunable emissions with large Stokes shifts. Furthermore, the protocol provides an opportunity to rapidly screen novel organic single-molecule whitelight materials with high fiuorescence quantum yields. The robust organic and low-cost white lightemitting diodes could rapidly be fabricated using the white-light-emitting material. Experimental data and theoretical calculations indicate that in the white-light dual emission the relatively short wavelength from high-lying singlet state emission and the relatively long wavelength from low-lying singlet state emission. The anti-Kasha dual-emission systems will provide a foundation for the development and application of organic single-molecule white light materials, effectively promoting the development and innovation of luminescent materials. In addition, this method demonstrated its potential application in the synthesis of new near-infrared(NIR) fiuorescence materials with large Stokes shifts based on the olefination of heterocycles.
基金supported by the National Natural Science Foundation of China(Grant Nos.12404085,12474122,52171188,51771127,and 52111530143)the Fund from DOE-BES(Grant No.DE-FG02-05ER46237)the Central Government Funds of Guiding Local Scientific and Technological Development for Sichuan Province,China(Grant No.2021ZYD0025)。
文摘Using exact diagonalization of the Hamiltonian and transition matrix in the energy eigenbasis,we perform model calculations of the magnetic relaxation rate in single-molecule magnets.A careful examination of the transition matrix reveals that resonant tunneling does not enhance transitions between the nearly degenerate states;rather,it suppresses them.Instead,transitions from one state in the degenerate pair to neighboring states of the other are significantly enhanced.We conduct a detailed analysis of the transition rates to clearly demonstrate how resonant tunneling modulates these processes.This work provides a substantial reinterpretation of the resonant magnetic relaxation in single-molecule magnets and clearly identifies the dominant relaxation pathways.
基金supported by the National Key Research and Development Program(No.2022YFE0107400)the internal research funding from Photonic View Technology Technology Co.,Ltd.the GuangCi Deep Mind Project of Ruijin Hospital Shanghai Jiao Tong University School of Medicine.
文摘The single-molecule detection tech-nique plays a pivotal role in elucidat-ing the fundamental mechanisms of various scientific processes at the molecular level,and holds essential im-portance in multiple fields including physics,biology,and chemistry.Re-cently,single-molecule detection has garnered increasing attention owing to its practical utility in medical diagno-sis,primarily due to its exceptional sensitivity and the minimal sample volume required for analysis.However,the conventional single-molecule technique,represented by total internal reflection microscopy,faces challenges such as sophisticated operation procedures and limited detection throughput,thereby impeding its broader application.To address these limitations,we have demonstrated single-molecule detection using an integrated silicon photonic chip,of-fering a cost-effective and user-friendly alternative.By employing basic optics,we efficiently introduce the excitation source for single-molecule fluorescence by harnessing the strong evanescent field of high refractive-index waveguides.Subsequently,fluorescence signals are collected using basic optics comprising a water-immersion objective,relay optics,and a digi-tal camera.Our results highlight a low-cost,high-throughput single-molecule technique achieved through the integrated silicon photonic chip.This innovative approach is promised to facilitate the widespread adoption of single-molecule fluorescence in medical diagnosis.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0709304)the National Natural Science Foundation of China(Grant Nos.12090051 and 12022409)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB37000000)the Youth Innovation Promotion Association of CAS(Grant Nos.2021009 and Y2021003)
文摘Physical biology is an interdisciplinary field that bridges biology with physical sciences and engineering.Singlemolecule physical biology focuses on dynamics of individual biomolecules and complexes,aiming to answering basic questions about their functions and mechanisms.It takes advantages of physical methodologies to gain quantitative understanding of biological processes,often engaging precise physical measurements of reconstructed objects to avoid interference from unnecessary complications.In this review,we(i)briefly introduce concepts of single-molecule physical biology,(ii)describe extensively used single-molecule methodologies that have been developed to address key questions in two important objects of single-molecule physical biology,namely,nucleic acid-interacting proteins and membraneinteracting proteins,and(iii)show by a few successful examples how one may use single-molecule methods to deepen our understanding of protein machines.
基金financially supported by the National Natural Science Foundation of China(No.22273079)Fundamental Research Funds for the Central Universities(No.2682025ZTPY004)。
文摘Quantifying the hydrogen bond(H-bond)strength of polymers is essential for rational design of advanced materials.However,direct measurement remains challenging because of the structural complexity of polymers and the weak nature of H-bonds.Vacuum-based singlemolecule force spectroscopy(Vac-SMFS)offers a new and precise approach for such measurements.Using polyallylamine(PAAm)as a model polymer,the intrinsic strength(i.e.,strength without external influences)of representative N―H…N H-bonds was quantified to be about 5.25 kJ·mol^(–1).Comparative Vac-SMFS analysis across different polymer systems revealed that the N―H…N H-bonds in PAAm are unexpectedly stronger than the N―H…O H-bonds in poly(N-isopropylacrylamide)(PNIPAM)and the O―H…O H-bonds in poly(hydroxyethyl methacrylate)(PHEMA).This trend contrasts with that of established small-molecule systems.These results highlight how side-chain length and spatial configuration dictate polymer H-bond strengths,expanding the fundamental knowledge of polymer interactions and enabling the rational design of next-generation functional materials.
基金This work was supported by the National Natural Science Foundation of China （90713024, 20821003, 30921004）, the National Basic Research Program of China （2007CB935601, 2010CB833706） and the Chinese Academy of Sciences.
文摘Transforming growth factor-β （TGF-β） binds with two transmembrane serine/threonine kinase receptors, type Ⅱ （TβRII） and type Ⅰ receptors （TβRⅠ）, and one accessory receptor, type Ⅲ receptor （TβRⅢ）, to transduce signals across cell membranes. Previous biochemical studies suggested that TβRI and TβRIII are preexisted homo-dimers. Using single-molecule microscopy to image green fluorescent protein-labeled membrane proteins, for the first time we have demonstrated that TβRI and TβRⅢ could exist as monomers at a low expression level. Upon TGF-β1 stimu- lation, TβRI follows the general ligand-induced receptor dimerization model for activation, but this process is TβRⅡ- dependent. The monomeric status of the non-kinase receptor TβRⅢ is unchanged in the presence of TGF-β1. With the increase of receptor expression, both TβRI and TβRIII can be assembled into dimers on cell surfaces.
基金We acknowledge primary financial supports from the National Key R&D Program of China(2017YFA0204901,2021YFA1200101 and 2021YFA1200102)the National Natural Science Foundation of China(22150013,21727806,21933001 and 22173050)+1 种基金the Tencent Foundation through the XPLORER PRIZE“Frontiers Science Center for New Organic Matter”at Nankai University(63181206).
文摘Single-molecule devices not only promise to provide an alternative strategy to break through the miniaturization and functionalization bottlenecks faced by traditional semiconductor devices,but also provide a reliable platform for exploration of the intrinsic properties of matters at the single-molecule level.Because the regulation of the electrical properties of single-molecule devices will be a key factor in enabling further advances in the development of molecular electronics,it is necessary to clarify the interactions between the charge transport occurring in the device and the external fields,particularly the optical field.This review mainly introduces the optoelectronic effects that are involved in single-molecule devices,including photoisomerization switching,photoconductance,plasmon-induced excitation,photovoltaic effect,and electroluminescence.We also summarize the optoelectronic mechanisms of single-molecule devices,with particular emphasis on the photoisomerization,photoexcitation,and photo-assisted tunneling processes.Finally,we focus the discussion on the opportunities and challenges arising in the single-molecule optoelectronics field and propose further possible breakthroughs.
