The origin of the Rayleigh scattering ring effect has been experimentally examined on a quantum dot/metal film system, in which CdTe quantum dots embedded in PVP are spincoated on a thin Au film. On the basis of the a...The origin of the Rayleigh scattering ring effect has been experimentally examined on a quantum dot/metal film system, in which CdTe quantum dots embedded in PVP are spincoated on a thin Au film. On the basis of the angle-dependent, optical measurements under different excitation schemes （i.e., wavelength and polarization）, we demonstrate that surface plasmon assisted directional radiation is responsible for such an effect. Moreover, an interesting phase-shift behavior is addressed.展开更多
We investigate the heat generation induced by electrical current in a normal-metal-molecular quantum dot-superconductor （NDS） system. By using nonequilibrium Green＇s function method, the heat generation Q is derive...We investigate the heat generation induced by electrical current in a normal-metal-molecular quantum dot-superconductor （NDS） system. By using nonequilibrium Green＇s function method, the heat generation Q is derived and studied in detail. The superconducting lead influences the heat generation significantly. An obvious step appears in Q - eV characteristics and the iocation of this step is related with the phonon frequency ωo. The heat generations exhibit very different behaviour in the condition eV 〈 △ and eV 〉 △ due to different tunneling mechanism. From the study of Q - eVg curves, there is an extra peak as eV 〉 △. The difference in this two cases is also shown in Q - ωo curve, an extra peak emerges as eV 〉 △.展开更多
A DNA fluorescence probe system based on fluorescence resonance energy transfer （FRET） from CdTe quantum dot （QD） donors to Au nanoparticle （AuNP） acceptors is presented. CdTe QDs, 2.5nm in diameter, as energy d...A DNA fluorescence probe system based on fluorescence resonance energy transfer （FRET） from CdTe quantum dot （QD） donors to Au nanoparticle （AuNP） acceptors is presented. CdTe QDs, 2.5nm in diameter, as energy donors, were prepared in water. Au nanoparticles, 16nm in diameter, as energy acceptors, were prepared from gold chloride by reduction. CdTe QDs were linked to 5＇-NH2-DNA through 1-ethyl-3-（dimethylaminopropyl）car- bodiimide hydrochloride （EDC） as a linker, and the 3＇-SH-DNA was self-assembled onto the surface of AuNPs. The hybridization of complementary double stranded DNA （dsDNA） bound to the QDs and AuNPs （CdTe-dsDNA-Au） determined the FRET distance of CdTe QDs and Au nanoparticles. Compared to the fluorescence of CdTe-DNA, the fluorescence of CdTe-DNA-Au conjugates decreased extremely, which indicated that the FRET occurred between CdTe QDs and Au nanoparticles. The fluorescence change of this conjugate depended on the ratio of Au-DNA to CdTe-DNA. When the AuNPs-DNA to QD-DNA ratio was 10：1, the FRET efficiency reached a maximum. The probe system would have a certain degree of fluorescence recovery when a complementary single stranded DNA was introduced into this system, which showed that the distance between CdTe QDs and Au nanoparticles was increased.展开更多
Photocatalytic hydrogen(H2)evolution is a promising approach for future sustainable energy utilization.However,it is still a great challenge to develop efficient and stable metal‐free photocatalysts with broadband so...Photocatalytic hydrogen(H2)evolution is a promising approach for future sustainable energy utilization.However,it is still a great challenge to develop efficient and stable metal‐free photocatalysts with broadband solar absorption in the visible region for H2 production.Metal‐free graphene quantum dot(GQD)is an emerging candidate for this purpose because of its good water‐solubility and tunable band gap.On the other hand,metal phosphides(Ni2P,Co2P,etc)have been demonstrated as novel noble‐metal‐free cocatalysts for water splitting,which can efficiently separate electron‐hole pairs and enhance the photocatalytic activities.Herein,we report for the first time on the use of OH‐functionalized GQDs(OH‐GQDs)photosensitizer coupled with Ni2P nanoparticles for photocatalytic H2 production withλ>420 nm light.The H2 production rate is^94 times higher than that of bare OH‐GQDs,which is even comparable to that of OH‐GQDs with 1.0 wt%Pt cocatalyst.This enhancement is probably due to the semiconductor‐cocatalyst interface interaction between Ni2P and OH‐GQDs to facilitate efficient charge transfer process.展开更多
Rapid, accurate and sensitive detection of particular DNA sequence is critical in fundamental biomedical research and clinical diagnostics. However, conventional approaches for DNA assay often suffer from cumbersome p...Rapid, accurate and sensitive detection of particular DNA sequence is critical in fundamental biomedical research and clinical diagnostics. However, conventional approaches for DNA assay often suffer from cumbersome procedures, long analysis time and insufficient sensitivity. Recently, single-particle detection technology has emerged as a powerful tool in the biosensing area due to its significant advantages of ultrahigh sensitivity, low sample-consumption and rapid analysis time. Especially, the introduction of novel nanomaterials has greatly promoted the development of single-particle detection and its applications for DNA sensing. In this review, we summarize the recent advance in single-particle detection strategies for DNA sensing, and focus mainly on metallic nanoparticle-and semiconductor quantum dot-based single-particle detection. We highlight the emerging trends in this field as well.展开更多
Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report...Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report a photoswitchable proton conductive ZIF-8 membrane by coencapsulating polystyrene sulfonate and graphene quantum dots into a ZIF-8 matrix(GQDs-PSS@ZIF-8) via a solidconfined conversion process. The proton conductivity of the GQDs-PSS@ZIF-8 membrane is 6.3 times higher than that of pristine ZIF-8 and can be reversibly switched by light due to photoluminescence quenching and the photothermal conversion effect, which converts light into heat. The local increase in temperature allows water molecules to escape from the porous channels, which cuts off the proton transport pathways and results in a decrease in proton conductivity. The proton conductivity is restored when the light is off owing to regaining water molecules, which act as proton carriers, from the surroundings. The GQDs-PSS@ZIF-8 membrane responds efficiently to light and exhibits an ON/OFF ratio of 12.8. This photogated proton conduction in MOFs has potential for the development and application of MOF-based protonic solids in advanced photoelectric devices.展开更多
In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopam...In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopamine （PDA） decorated Au nanoparticles （Au@PDA NPs） for ultrasensitive detection of carcinoembryonic antigen （CEA） has been successfully achieved. The ECL of CdSe@ZnS QDs with different sizes has been investigated carefully, especially cooperation with TiO2 NPs. Au@PDA NPs have been synthesized and characterized by transmission electron microscopy （TEM） and UV-Vis spectrum, which acted as ECL quenchers to label the secondary antibody （Ab2） of CEA to form Ab2/Au@PDA NPs conjugates. The sandwich-structured immunosensor was formed between capture antibody （Abl） on CdSe@ZnS QDs/TiO2 NPs/glassy carbon electrode, CEA and Ab2/Au@PDA NPs conjugates, resulting in a proportional ECL quenching signal relevant to the CEA concentration. Thus, CEA as a model biomarker has been detected in the linear range from 0.001 to 100 ng mL^-1 with a limit of detection of 0.35 pg mL^-1 （S/N = 3）.展开更多
We investigate the low-energy electronic structure ofa Weyl semimetal quantum dot （QD） with a simple model Hamiltonian with only two Weyl points. Distinguished from the semiconductor and topological insulator QDs, t...We investigate the low-energy electronic structure ofa Weyl semimetal quantum dot （QD） with a simple model Hamiltonian with only two Weyl points. Distinguished from the semiconductor and topological insulator QDs, there exist both surface and bulk states near the Fermi level in Weyl semimetal QDs. The surface state, distributed near the side surface of the QD, contributes a circular persistent current, an orbital magnetic moment, and a chiral spin polarization with spin-current locking. There are always surface states even for a strong magnetic field, even though a given surface state gradually evolves into a Landau level with increasing magnetic field. It indicates that these unique properties can be tuned via the QD size. In addition, we show the correspondence to the electronic structures of a three-dimensional Weyl semimetal, such as Wey[ point and Fermi arc. Because a QD has the largest surface-to-volume ratio, it provides a new platform to verify Weyl semimetal by separating and detecting the signals of surface states. Besides, the study of Weyl QDs is also necessary for potential applications in nanoelectronics.展开更多
The interracial electron transfer （IET） dynamics of single CdSe core/multilayer shell （CdS2MLZnCdS1MLZnSIML） quantum dots （QDs） on the （110） surface of a futile TiO2 single crystal and TiO2 nanoparticles have ...The interracial electron transfer （IET） dynamics of single CdSe core/multilayer shell （CdS2MLZnCdS1MLZnSIML） quantum dots （QDs） on the （110） surface of a futile TiO2 single crystal and TiO2 nanoparticles have been compared. The fluorescence decay rates of single QDs on TiO2 are faster than those on glass, an insulating substrate, due to lET from the QDs to TiO2. Whereas the average IET rates are similar for QDs on the single crystal and nanoparticles, the distribution of lET rates is much broader in the latter, indicating a broad distribution of QD adsorption sites on the TiO2 nanoparticles.展开更多
基金This work was partially supported by the Ministry of Science and Technology of China （No.HH2060030013 and No.2016YFA0200602）, the National Natural Science Foundation of China （No.21573211 and No.21421063）, the Chinese Academy of Sciences （No.XDB01020000）, and the Fundamental Research Funds for the Central Universities （No.WK2340000063）.
文摘The origin of the Rayleigh scattering ring effect has been experimentally examined on a quantum dot/metal film system, in which CdTe quantum dots embedded in PVP are spincoated on a thin Au film. On the basis of the angle-dependent, optical measurements under different excitation schemes （i.e., wavelength and polarization）, we demonstrate that surface plasmon assisted directional radiation is responsible for such an effect. Moreover, an interesting phase-shift behavior is addressed.
基金Supported by the Scientific Research Fund of Hunan Provincial Education Department under Grant No. 10B022Hunan Provincial Natural Science Foundation of China under Grant No. 11JJ4005
文摘We investigate the heat generation induced by electrical current in a normal-metal-molecular quantum dot-superconductor （NDS） system. By using nonequilibrium Green＇s function method, the heat generation Q is derived and studied in detail. The superconducting lead influences the heat generation significantly. An obvious step appears in Q - eV characteristics and the iocation of this step is related with the phonon frequency ωo. The heat generations exhibit very different behaviour in the condition eV 〈 △ and eV 〉 △ due to different tunneling mechanism. From the study of Q - eVg curves, there is an extra peak as eV 〉 △. The difference in this two cases is also shown in Q - ωo curve, an extra peak emerges as eV 〉 △.
基金Supported by the Natural Science Foundation of Tianjin（Nos.06TXTJJC14400, 07JCYBJC15900） and Young Teacher Foun-dation of Tianjin Polytechnic University （No.029624）.
文摘A DNA fluorescence probe system based on fluorescence resonance energy transfer （FRET） from CdTe quantum dot （QD） donors to Au nanoparticle （AuNP） acceptors is presented. CdTe QDs, 2.5nm in diameter, as energy donors, were prepared in water. Au nanoparticles, 16nm in diameter, as energy acceptors, were prepared from gold chloride by reduction. CdTe QDs were linked to 5＇-NH2-DNA through 1-ethyl-3-（dimethylaminopropyl）car- bodiimide hydrochloride （EDC） as a linker, and the 3＇-SH-DNA was self-assembled onto the surface of AuNPs. The hybridization of complementary double stranded DNA （dsDNA） bound to the QDs and AuNPs （CdTe-dsDNA-Au） determined the FRET distance of CdTe QDs and Au nanoparticles. Compared to the fluorescence of CdTe-DNA, the fluorescence of CdTe-DNA-Au conjugates decreased extremely, which indicated that the FRET occurred between CdTe QDs and Au nanoparticles. The fluorescence change of this conjugate depended on the ratio of Au-DNA to CdTe-DNA. When the AuNPs-DNA to QD-DNA ratio was 10：1, the FRET efficiency reached a maximum. The probe system would have a certain degree of fluorescence recovery when a complementary single stranded DNA was introduced into this system, which showed that the distance between CdTe QDs and Au nanoparticles was increased.
文摘Photocatalytic hydrogen(H2)evolution is a promising approach for future sustainable energy utilization.However,it is still a great challenge to develop efficient and stable metal‐free photocatalysts with broadband solar absorption in the visible region for H2 production.Metal‐free graphene quantum dot(GQD)is an emerging candidate for this purpose because of its good water‐solubility and tunable band gap.On the other hand,metal phosphides(Ni2P,Co2P,etc)have been demonstrated as novel noble‐metal‐free cocatalysts for water splitting,which can efficiently separate electron‐hole pairs and enhance the photocatalytic activities.Herein,we report for the first time on the use of OH‐functionalized GQDs(OH‐GQDs)photosensitizer coupled with Ni2P nanoparticles for photocatalytic H2 production withλ>420 nm light.The H2 production rate is^94 times higher than that of bare OH‐GQDs,which is even comparable to that of OH‐GQDs with 1.0 wt%Pt cocatalyst.This enhancement is probably due to the semiconductor‐cocatalyst interface interaction between Ni2P and OH‐GQDs to facilitate efficient charge transfer process.
基金supported by the National Natural Science Foundation of China (21325523, 21527811)the Shandong Province Science Foundation for Youths (ZR2016HQ07)the Award for Team Leader Program of Taishan Scholars of Shandong Province, China
文摘Rapid, accurate and sensitive detection of particular DNA sequence is critical in fundamental biomedical research and clinical diagnostics. However, conventional approaches for DNA assay often suffer from cumbersome procedures, long analysis time and insufficient sensitivity. Recently, single-particle detection technology has emerged as a powerful tool in the biosensing area due to its significant advantages of ultrahigh sensitivity, low sample-consumption and rapid analysis time. Especially, the introduction of novel nanomaterials has greatly promoted the development of single-particle detection and its applications for DNA sensing. In this review, we summarize the recent advance in single-particle detection strategies for DNA sensing, and focus mainly on metallic nanoparticle-and semiconductor quantum dot-based single-particle detection. We highlight the emerging trends in this field as well.
基金supported by the National Natural Science Foundation of China (21875212)the Key Program of National Natural Science Foundation (51632008)+2 种基金the Major R&D Plan of Zhejiang Natural Science Foundation (LD18E020001)the National Key Research and Development Program (2016YFA0200204)the Fundamental Research Funds for the Central Universities。
文摘Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report a photoswitchable proton conductive ZIF-8 membrane by coencapsulating polystyrene sulfonate and graphene quantum dots into a ZIF-8 matrix(GQDs-PSS@ZIF-8) via a solidconfined conversion process. The proton conductivity of the GQDs-PSS@ZIF-8 membrane is 6.3 times higher than that of pristine ZIF-8 and can be reversibly switched by light due to photoluminescence quenching and the photothermal conversion effect, which converts light into heat. The local increase in temperature allows water molecules to escape from the porous channels, which cuts off the proton transport pathways and results in a decrease in proton conductivity. The proton conductivity is restored when the light is off owing to regaining water molecules, which act as proton carriers, from the surroundings. The GQDs-PSS@ZIF-8 membrane responds efficiently to light and exhibits an ON/OFF ratio of 12.8. This photogated proton conduction in MOFs has potential for the development and application of MOF-based protonic solids in advanced photoelectric devices.
基金supported by the National Natural Science Foundation of China (21575022, 21535003)the National High Technology Research and Development Program of China (2015AA020502)+1 种基金the Open Research Fund of Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast Universitythe Fundamental Research Funds for the Central Universities (KYLX15-0127)
文摘In this work, a double signal amplified immunosen- sor based on the enhanced CdSe@ZnS quantum dots （QDs） electrochemiluminescence （ECL） via TiO2 nanoparticles （TiO2 NPs） and the outstanding quencher of polydopamine （PDA） decorated Au nanoparticles （Au@PDA NPs） for ultrasensitive detection of carcinoembryonic antigen （CEA） has been successfully achieved. The ECL of CdSe@ZnS QDs with different sizes has been investigated carefully, especially cooperation with TiO2 NPs. Au@PDA NPs have been synthesized and characterized by transmission electron microscopy （TEM） and UV-Vis spectrum, which acted as ECL quenchers to label the secondary antibody （Ab2） of CEA to form Ab2/Au@PDA NPs conjugates. The sandwich-structured immunosensor was formed between capture antibody （Abl） on CdSe@ZnS QDs/TiO2 NPs/glassy carbon electrode, CEA and Ab2/Au@PDA NPs conjugates, resulting in a proportional ECL quenching signal relevant to the CEA concentration. Thus, CEA as a model biomarker has been detected in the linear range from 0.001 to 100 ng mL^-1 with a limit of detection of 0.35 pg mL^-1 （S/N = 3）.
基金supported by the National Natural Science Foundation of China(Grants Nos.11747122,11274364,and 11574007)the National Basic Research Program of China(Grant Nos.2017YFA0303301,and2015CB921102)+1 种基金the Natural Science Foundation of Shandong Province(Grant No.ZR2018PA007)the Doctoral Foundation of University of Jinan(Grant No.160100147)
文摘We investigate the low-energy electronic structure ofa Weyl semimetal quantum dot （QD） with a simple model Hamiltonian with only two Weyl points. Distinguished from the semiconductor and topological insulator QDs, there exist both surface and bulk states near the Fermi level in Weyl semimetal QDs. The surface state, distributed near the side surface of the QD, contributes a circular persistent current, an orbital magnetic moment, and a chiral spin polarization with spin-current locking. There are always surface states even for a strong magnetic field, even though a given surface state gradually evolves into a Landau level with increasing magnetic field. It indicates that these unique properties can be tuned via the QD size. In addition, we show the correspondence to the electronic structures of a three-dimensional Weyl semimetal, such as Wey[ point and Fermi arc. Because a QD has the largest surface-to-volume ratio, it provides a new platform to verify Weyl semimetal by separating and detecting the signals of surface states. Besides, the study of Weyl QDs is also necessary for potential applications in nanoelectronics.
基金supported by the National Science Foundation (CHE-0848556)the donors of the Petroleum Research Fund of the American Chemical Society (PRF #49286-ND6)
文摘The interracial electron transfer （IET） dynamics of single CdSe core/multilayer shell （CdS2MLZnCdS1MLZnSIML） quantum dots （QDs） on the （110） surface of a futile TiO2 single crystal and TiO2 nanoparticles have been compared. The fluorescence decay rates of single QDs on TiO2 are faster than those on glass, an insulating substrate, due to lET from the QDs to TiO2. Whereas the average IET rates are similar for QDs on the single crystal and nanoparticles, the distribution of lET rates is much broader in the latter, indicating a broad distribution of QD adsorption sites on the TiO2 nanoparticles.
