Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developin...Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains challenging.Herein,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the surface.These NWs possess uniform sizes and well-controlled atomic arrangements.Compared to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based catalysts.Additionally,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/C.The ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.展开更多
We demonstrate the regioselective growth of Au on Au nanobipyramids,either with etching of the tips,uniform coating except the tips,or forming a single island on the axial tip or an island on the equatorial corner.Imp...We demonstrate the regioselective growth of Au on Au nanobipyramids,either with etching of the tips,uniform coating except the tips,or forming a single island on the axial tip or an island on the equatorial corner.Importantly,the regioselectivity not only arises from the local curvature,as suggested by the recent literature,but also critically depends on the extent of ligand coverage on the seed surface.It is important to consider the competitive growth together with the curvature−ligand interplay:when there are insufficient ligands,they bind preferentially to the sharp tip for high surface energy,so that the remaining growth materials are diverted elsewhere;when the bipyramid is fully covered by ligands,the growth then selectively occurs at the tips because of the larger gaps among the ligands there.Our results demonstrate the great potentials in the rational design and synthesis when constructing sophisticated hybrid structures for functional nanomaterials.展开更多
Bimetallic nanoparticles exhibit a synergistic effect that critically depends on their surface composition,but such promotion mechanisms become vague with varying surface compositions.Here,alumina supported Ag@Pd core...Bimetallic nanoparticles exhibit a synergistic effect that critically depends on their surface composition,but such promotion mechanisms become vague with varying surface compositions.Here,alumina supported Ag@Pd core–shell and PdAg alloy structure with controlled size and surface compositions were prepared to demonstrate synergetic mechanisms,particularly,ligand and strain effects on activity and ethylene selectivity for acetylene hydrogenation.The performance evaluation indicates that Ag@Pd catalysts with well-controlled Pd-shell thickness can effectively lower apparent activation energy and improve ethylene selectivity.Hydrogenation activity increases from 0.019 to 0.062 s^(-1) with decreasing Pd-shell thickness under mild conditions,which is 3–6 times higher than their alloyed and monometallic counterparts.Combined characterizations and density functional theory are conducted to reveal such shell-thickness-dependent performance.The ligand effect arising from Ag alloying in the interface of Ag@Pd2ML observes the strongest binding of acetylene,but it diminished sharply and the strain effect gets more prevailing with increasing shell thickness.The competition of ethylene desorption and deephydrogenation were also investigated to understand the selectivity governing factors,and the selectivity descriptor(0.5BE(C_(2)H_(4))–BE(H))was built to match the contribution of ligand and strain effect on the different surfaces of Pd-Ag bimetallic NPs.The exploration of synergetic mechanisms among bimetallic NPs with varied structure and surface compositions in this work can help us to deepen the understanding catalyst structure–activity relationship and provide a feasible way to optimize the overall catalytic performance.展开更多
The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like ...The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like screening model. Association pathway and dissocia-tion pathway were investigated by the comparison of several energies. The cleavage energy of Pd（PR3）2 complex was calculated, as well as the oxidative addition reaction barrier energy of Pd（PR3）n （n=1,2） with aryl bromide in N,N-dimethylformamide solvent. This study proved that the ligands volume possessed a great impact on the mechanism of oxidative addition： less bulky ligand palladium associated with aryl bromide via two donor ligands,but larger bulky ligand palladium coordinated via monoligand.展开更多
The reactivity of the metalloporphyrins was closely related to their ligand effect at axial position. The electronic properties of six model Co（II） porphyrins are investigated by spectral and electrochemical methods...The reactivity of the metalloporphyrins was closely related to their ligand effect at axial position. The electronic properties of six model Co（II） porphyrins are investigated by spectral and electrochemical methods. Structural parameters of the COOI） complexes are directly obtained from their crystal structures. We demonstrate that the unpaired 3d electron of low-spin Co（II） ions in nonplanar Co（II） porphyrin complexes activated by core contraction of porphyrin macrocycles can be further activated by the axial ligation of imidazole. The activated electron can combine with a n orbital of the porphyrin ring to form a new d-π orbital, which can induce the Q-band of Co（II） porphyrins to visibly split. Addition of imidazole causes the Co（II）/Co（III） and Co（II）/Co（I） reactions to shift to more negative potential. Our results indicate that strong axial ligation and core contraction both play important roles in electron transfer in redox catalysis involving Co（II） complexes.展开更多
We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed ...We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed by an Ag17 core with C3 symmetry and the remaining 15 Ag atoms bond to each other and coordinate with the 24 surface ligands.When applied as electrocatalyst for CO_(2) reduction reaction(CO_(2)RR),Ag_(32) exhibited the highest Faradaic efficiency(FE)of CO up to 96.44%at−0.8 V with hydrogen evolution being significantly suppressed in a wide potential range,meanwhile it has a reaction rate constant of 0.242 min−1 at room temperature and an activation energy of 45.21 kJ·mol−1 in catalyzing the reduction of 4-nitrophenol,both markedly superior than the thiolate and phosphine ligand co-protected Ag_(32) nanocluster.Such strong ligand effect was further understood by density functional theory(DFT)calculations,as it revealed that,one single ligand stripping off from the intact cluster can create the undercoordinated Ag atom as the catalytically active site for both clusters,but alkynyl-protected Ag_(32) nanocluster possesses a smaller energy barrier for forming the key*COOH intermediate in CO_(2)RR,and favors the adsorption of 4-nitrophenol.This study not only discovers a new member of homoleptic alkynyl-protected Ag nanocluster,but also highlights the great potentials of employing alkynyl-protected Ag nanoclusters as bifunctional catalysts toward various reactions.展开更多
The enhancement effects of Y ( Ⅲ) ions on the fluorescence of Ce ( Ⅲ) in Ce ( Ⅲ)-Y ( Ⅲ)-PMMA (polymethylmethacrylate ) or Ce ( Ⅲ)-Y ( Ⅲ)-PVC (polyvinyl chloride ) complex systems were observed. The influence of ...The enhancement effects of Y ( Ⅲ) ions on the fluorescence of Ce ( Ⅲ) in Ce ( Ⅲ)-Y ( Ⅲ)-PMMA (polymethylmethacrylate ) or Ce ( Ⅲ)-Y ( Ⅲ)-PVC (polyvinyl chloride ) complex systems were observed. The influence of Y ( Ⅲ) ions on the emission spectra of PMMA ligands in PMMA-Y ( Ⅲ) and the fluorescent enhance- ment of Y( Ⅲ) on Ce( Ⅲ) emission in PMMA-Ce-Y by Y( Ⅲ) ion were studied. It was also of interest to note that when Y ( Ⅲ) ions were added into PMMA and into bpy(bipyridine ) , respectively , the emission spectrum of PMMA ligands was split into fine structure bands by Y ( Ⅲ) , and the fluorescence intensities of bpy ligands in bpy-Y ( Ⅲ) complexes were considerably increased.展开更多
The effects of peptides,amino acids and organic bases as an axial ligand on reaction ac- tivities in the electrocarboxylation of benzyl chloride with CO_2 catalyzed by CoTPP are reported. The imidazole organic base,pe...The effects of peptides,amino acids and organic bases as an axial ligand on reaction ac- tivities in the electrocarboxylation of benzyl chloride with CO_2 catalyzed by CoTPP are reported. The imidazole organic base,peptide containing —SH and amino acid containing imidazolyl en- hance the catalytic activity.The effect of imidazole amounts on the catalytic activity of CoTPP is studied.展开更多
The ligand exchange reaction is a typical reaction of ferrocenes. This reaction proceeds via the abstraction of a cyclopentadienyl ring by a Lewis acid followed by coordination of an aromatic compound to the resulting...The ligand exchange reaction is a typical reaction of ferrocenes. This reaction proceeds via the abstraction of a cyclopentadienyl ring by a Lewis acid followed by coordination of an aromatic compound to the resulting species. This reaction with conventional heating requires a long reaction time. Furthermore, the reactions with heterocycles are lower than those with the corresponding hydrocarbons, and do not produce any products in some cases. In this paper, the ligand exchange reaction of ferrocene and a heterocyclic aromatic compound during microwave irradiation and its effect are discussed. As a result, for some heterocycles, the decrease in the reaction time was confirmed. Furthermore, under the microwave irradiation conditions, the tendency in which the difference in their reactivities became low was confirmed.展开更多
We present an extended analytical model including the depletion effect and the dimension of ligand-receptor complex, aiming to elucidate their influences on endocytosis of spherocylindrical nanoparticles （NPs）. It i...We present an extended analytical model including the depletion effect and the dimension of ligand-receptor complex, aiming to elucidate their influences on endocytosis of spherocylindrical nanoparticles （NPs）. It is found that the dimension of ligand-receptor complex （δ） and the depletion effect interrelatedly govern the optimal conditions of NP endocytosis. The endocytosis phase diagram constructed in the space of NP radius and relative aspect ratio indicates that the endocytosis of NP is enhanced evidently by reducing the optimal radius and the threshold radius of endocytosed NP. Meanwhile, through thermodynamic and kinetic analysis of the diffusion of receptors, the dependence of diffusion length on depletion effect and the dimension of ligand-receptor complex can be identified in great detail. For small aspect ratio, diffusion length decreases with increasing concentration c of small bioparticles in cellular environment. Endocytosis speed corresponding to large radius R and high concentration c of small bioparticles strongly depends on the increasing （2r-δ）. These results may show some highlights into the conscious design of NPs for diagnostic agents and therapeutic drug delivery applications.展开更多
Objective: In order to explore the radioprotective effects of the expression of hematopoietic growth factors regulated by radio-inducible promoter on radiation injury. Methods:The human FL (Flt3 ligand) cDNA and EGFP ...Objective: In order to explore the radioprotective effects of the expression of hematopoietic growth factors regulated by radio-inducible promoter on radiation injury. Methods:The human FL (Flt3 ligand) cDNA and EGFP (enhanced green fluorescent protein) cDNA were linked together with IRES and then inserted into the eukaryotic expression vector pCI-Egr, which was constructed by substituting CMV promoter in pCIneo with the Egr-1 promoter (Egr-EF). The vector was transferred into human bone marrow stromal ...展开更多
Electrocatalytic oxygen reduction and evolution reactions are involved in new energy conversion and storage technologies,such as various fuel cells and metal-air batteries and also water splitting devices[1,2].However...Electrocatalytic oxygen reduction and evolution reactions are involved in new energy conversion and storage technologies,such as various fuel cells and metal-air batteries and also water splitting devices[1,2].However,both reactions are very slow in kinetics,and thus catalysts are required[3,4].展开更多
Atomically precise metal nanoclusters(MNCs),as a potential type of photoacoustic(PA)contrast agent,are limited in application due to their low PA conversion efficiency(PACE).Here,with hydrophilic Au25SR18(SR=thiolate)...Atomically precise metal nanoclusters(MNCs),as a potential type of photoacoustic(PA)contrast agent,are limited in application due to their low PA conversion efficiency(PACE).Here,with hydrophilic Au25SR18(SR=thiolate)as model NCs,we present a result that weakly polar solvent induces aggregation,which effectively enhances PA intensity and PACE.The PA intensity and PACE are highly dependent on the degree of aggregation,while the aggregation-enhanced PA intensity(AEPA)positively correlates to the protected ligands.Such an AEPA phenomenon indicates that aggregation actually accelerates the intramolecular motion of Au NCs,and enlarges the proportion of excited state energy dissipated through vibrational relaxation.This result conflicts with the restriction of intramolecular motion mechanism of aggregation-induced emission.Further experiments show that the increased energy of AEPA originates from the aggregation inhibiting the intermolecular energy transfer from excited Au NCs to their surrounding medium molecules,including solvent molecule and dissolved oxygen,rather than restricting radiative relaxations.This study develops a new strategy for enhancing the PA intensity of Au NCs,and contributes to a deeper understanding of the origin of the PA signal and the excited state energy dissipation processes for MNCs.展开更多
基金the National Natural Science Foundation of China(No.22275009)SINOPEC(contact No.421028)Fundamental Research Funds for the Central Universities(No.XK2020-02).
文摘Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains challenging.Herein,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the surface.These NWs possess uniform sizes and well-controlled atomic arrangements.Compared to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based catalysts.Additionally,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/C.The ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.
基金support from the National Natural Science Foundation of China General Program(No.21673117,H.C.)Major Program(No.91956109,H.C.)+2 种基金Zhejiang Provincial Natural Science Foundation of China Major Program(No.2022XHSJJ002,H.C.)Jiangsu Science and Technology Plan(BK20211258)Start-up Fund from Westlake University.
文摘We demonstrate the regioselective growth of Au on Au nanobipyramids,either with etching of the tips,uniform coating except the tips,or forming a single island on the axial tip or an island on the equatorial corner.Importantly,the regioselectivity not only arises from the local curvature,as suggested by the recent literature,but also critically depends on the extent of ligand coverage on the seed surface.It is important to consider the competitive growth together with the curvature−ligand interplay:when there are insufficient ligands,they bind preferentially to the sharp tip for high surface energy,so that the remaining growth materials are diverted elsewhere;when the bipyramid is fully covered by ligands,the growth then selectively occurs at the tips because of the larger gaps among the ligands there.Our results demonstrate the great potentials in the rational design and synthesis when constructing sophisticated hybrid structures for functional nanomaterials.
基金supported by National Key Research&Development Program of China (2022YFA1506200)the National Natural Science Foundations of China (22078007, 21627813, 21706009,22002085)+3 种基金Guangdong Basic and Applied Basic Research Foundation (2020A1515110832)the Fundamental Research Funds for the Central Universities (buctrc201921, JD2223)Innovative Achievement Commercialization Service-Platform of Industrial CatalysisChemistry and Chemical Engineering Guangdong Laboratory for a startup funding support(2111001)
文摘Bimetallic nanoparticles exhibit a synergistic effect that critically depends on their surface composition,but such promotion mechanisms become vague with varying surface compositions.Here,alumina supported Ag@Pd core–shell and PdAg alloy structure with controlled size and surface compositions were prepared to demonstrate synergetic mechanisms,particularly,ligand and strain effects on activity and ethylene selectivity for acetylene hydrogenation.The performance evaluation indicates that Ag@Pd catalysts with well-controlled Pd-shell thickness can effectively lower apparent activation energy and improve ethylene selectivity.Hydrogenation activity increases from 0.019 to 0.062 s^(-1) with decreasing Pd-shell thickness under mild conditions,which is 3–6 times higher than their alloyed and monometallic counterparts.Combined characterizations and density functional theory are conducted to reveal such shell-thickness-dependent performance.The ligand effect arising from Ag alloying in the interface of Ag@Pd2ML observes the strongest binding of acetylene,but it diminished sharply and the strain effect gets more prevailing with increasing shell thickness.The competition of ethylene desorption and deephydrogenation were also investigated to understand the selectivity governing factors,and the selectivity descriptor(0.5BE(C_(2)H_(4))–BE(H))was built to match the contribution of ligand and strain effect on the different surfaces of Pd-Ag bimetallic NPs.The exploration of synergetic mechanisms among bimetallic NPs with varied structure and surface compositions in this work can help us to deepen the understanding catalyst structure–activity relationship and provide a feasible way to optimize the overall catalytic performance.
基金This work was supported by the National Natural Science Foundation of China （No.20776089） and the New Century Excellent Talents Program of Ministry of Education （No.NCET-05-0783）. The State Key Laboratory of Polymer Materials Engineering in Sichuan University was acknowledged for providing dmol3 modules and Prof. Ying Xue, Xiang-yuan Li, and Quan Zhu were grateful for the useful discussions.
文摘The process and mechanism of the ligand volume controlled Pd（PR3）2 （PR3=PH3, PMe3, and PtBu3） oxidative addition with aryl bromide were investigated, using density functional theory method with the conductor-like screening model. Association pathway and dissocia-tion pathway were investigated by the comparison of several energies. The cleavage energy of Pd（PR3）2 complex was calculated, as well as the oxidative addition reaction barrier energy of Pd（PR3）n （n=1,2） with aryl bromide in N,N-dimethylformamide solvent. This study proved that the ligands volume possessed a great impact on the mechanism of oxidative addition： less bulky ligand palladium associated with aryl bromide via two donor ligands,but larger bulky ligand palladium coordinated via monoligand.
基金This work was supported by the National Natural Science Foundation of China （No. 21575166, and 21372069）, and the Scientific Research Fund of Hunan Provincial Education Department （No. 15K042）.
文摘The reactivity of the metalloporphyrins was closely related to their ligand effect at axial position. The electronic properties of six model Co（II） porphyrins are investigated by spectral and electrochemical methods. Structural parameters of the COOI） complexes are directly obtained from their crystal structures. We demonstrate that the unpaired 3d electron of low-spin Co（II） ions in nonplanar Co（II） porphyrin complexes activated by core contraction of porphyrin macrocycles can be further activated by the axial ligation of imidazole. The activated electron can combine with a n orbital of the porphyrin ring to form a new d-π orbital, which can induce the Q-band of Co（II） porphyrins to visibly split. Addition of imidazole causes the Co（II）/Co（III） and Co（II）/Co（I） reactions to shift to more negative potential. Our results indicate that strong axial ligation and core contraction both play important roles in electron transfer in redox catalysis involving Co（II） complexes.
基金supported by the Open Fund of Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications(No.2021A07)support from Guangdong Natural Science Funds(No.2022A1515011840)+2 种基金the National Natural Science Foundation of China(No.21805170)the National Natural Science Foundation of China(No.21903008)the Chongqing Science and Technology Commission(No.cstc2020jcyj-msxmX0382).
文摘We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed by an Ag17 core with C3 symmetry and the remaining 15 Ag atoms bond to each other and coordinate with the 24 surface ligands.When applied as electrocatalyst for CO_(2) reduction reaction(CO_(2)RR),Ag_(32) exhibited the highest Faradaic efficiency(FE)of CO up to 96.44%at−0.8 V with hydrogen evolution being significantly suppressed in a wide potential range,meanwhile it has a reaction rate constant of 0.242 min−1 at room temperature and an activation energy of 45.21 kJ·mol−1 in catalyzing the reduction of 4-nitrophenol,both markedly superior than the thiolate and phosphine ligand co-protected Ag_(32) nanocluster.Such strong ligand effect was further understood by density functional theory(DFT)calculations,as it revealed that,one single ligand stripping off from the intact cluster can create the undercoordinated Ag atom as the catalytically active site for both clusters,but alkynyl-protected Ag_(32) nanocluster possesses a smaller energy barrier for forming the key*COOH intermediate in CO_(2)RR,and favors the adsorption of 4-nitrophenol.This study not only discovers a new member of homoleptic alkynyl-protected Ag nanocluster,but also highlights the great potentials of employing alkynyl-protected Ag nanoclusters as bifunctional catalysts toward various reactions.
文摘The enhancement effects of Y ( Ⅲ) ions on the fluorescence of Ce ( Ⅲ) in Ce ( Ⅲ)-Y ( Ⅲ)-PMMA (polymethylmethacrylate ) or Ce ( Ⅲ)-Y ( Ⅲ)-PVC (polyvinyl chloride ) complex systems were observed. The influence of Y ( Ⅲ) ions on the emission spectra of PMMA ligands in PMMA-Y ( Ⅲ) and the fluorescent enhance- ment of Y( Ⅲ) on Ce( Ⅲ) emission in PMMA-Ce-Y by Y( Ⅲ) ion were studied. It was also of interest to note that when Y ( Ⅲ) ions were added into PMMA and into bpy(bipyridine ) , respectively , the emission spectrum of PMMA ligands was split into fine structure bands by Y ( Ⅲ) , and the fluorescence intensities of bpy ligands in bpy-Y ( Ⅲ) complexes were considerably increased.
文摘The effects of peptides,amino acids and organic bases as an axial ligand on reaction ac- tivities in the electrocarboxylation of benzyl chloride with CO_2 catalyzed by CoTPP are reported. The imidazole organic base,peptide containing —SH and amino acid containing imidazolyl en- hance the catalytic activity.The effect of imidazole amounts on the catalytic activity of CoTPP is studied.
文摘The ligand exchange reaction is a typical reaction of ferrocenes. This reaction proceeds via the abstraction of a cyclopentadienyl ring by a Lewis acid followed by coordination of an aromatic compound to the resulting species. This reaction with conventional heating requires a long reaction time. Furthermore, the reactions with heterocycles are lower than those with the corresponding hydrocarbons, and do not produce any products in some cases. In this paper, the ligand exchange reaction of ferrocene and a heterocyclic aromatic compound during microwave irradiation and its effect are discussed. As a result, for some heterocycles, the decrease in the reaction time was confirmed. Furthermore, under the microwave irradiation conditions, the tendency in which the difference in their reactivities became low was confirmed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11047022,11204045,and 11464004)the Tracking Key Program of Social Development of Guizhou Province,China(Grant Nos.SY20123089 and SZ20113069)+2 种基金the General Financial Grant from the China Postdoctoral Science Foundation(Grant No.2014M562341)the Research Foundation for Young University Teachers from Guizhou University(Grant No.201311)the College Innovation Talent Team of Guizhou Province,China(Grant No.(2014)32)
文摘We present an extended analytical model including the depletion effect and the dimension of ligand-receptor complex, aiming to elucidate their influences on endocytosis of spherocylindrical nanoparticles （NPs）. It is found that the dimension of ligand-receptor complex （δ） and the depletion effect interrelatedly govern the optimal conditions of NP endocytosis. The endocytosis phase diagram constructed in the space of NP radius and relative aspect ratio indicates that the endocytosis of NP is enhanced evidently by reducing the optimal radius and the threshold radius of endocytosed NP. Meanwhile, through thermodynamic and kinetic analysis of the diffusion of receptors, the dependence of diffusion length on depletion effect and the dimension of ligand-receptor complex can be identified in great detail. For small aspect ratio, diffusion length decreases with increasing concentration c of small bioparticles in cellular environment. Endocytosis speed corresponding to large radius R and high concentration c of small bioparticles strongly depends on the increasing （2r-δ）. These results may show some highlights into the conscious design of NPs for diagnostic agents and therapeutic drug delivery applications.
基金National Natural Science Foundation of China(No 39900040)Natiorlal Natural Science Outstanding Youth Foundation of China(No 39825111).
文摘Objective: In order to explore the radioprotective effects of the expression of hematopoietic growth factors regulated by radio-inducible promoter on radiation injury. Methods:The human FL (Flt3 ligand) cDNA and EGFP (enhanced green fluorescent protein) cDNA were linked together with IRES and then inserted into the eukaryotic expression vector pCI-Egr, which was constructed by substituting CMV promoter in pCIneo with the Egr-1 promoter (Egr-EF). The vector was transferred into human bone marrow stromal ...
基金the support from the National Natural Science Foundation of China(21773146,22171176 and 22102092)the Fok Ying-Tong Education Foundation for Outstanding Young Teachers in University+2 种基金the Research Funds of Shaanxi Normal Universitythe Fundamental Research Funds for the Central Universitiesthe NRF of Korea(NRF-2021R1A3B1076539 and NRF-2020R1I1A1A01074630)。
文摘Electrocatalytic oxygen reduction and evolution reactions are involved in new energy conversion and storage technologies,such as various fuel cells and metal-air batteries and also water splitting devices[1,2].However,both reactions are very slow in kinetics,and thus catalysts are required[3,4].
基金Natural Science Foundation of Shandong Province,Grant/Award Number:ZR2020MB063Taishan Scholar Program of Shandong Province,Grant/Award Number:ts201511027。
文摘Atomically precise metal nanoclusters(MNCs),as a potential type of photoacoustic(PA)contrast agent,are limited in application due to their low PA conversion efficiency(PACE).Here,with hydrophilic Au25SR18(SR=thiolate)as model NCs,we present a result that weakly polar solvent induces aggregation,which effectively enhances PA intensity and PACE.The PA intensity and PACE are highly dependent on the degree of aggregation,while the aggregation-enhanced PA intensity(AEPA)positively correlates to the protected ligands.Such an AEPA phenomenon indicates that aggregation actually accelerates the intramolecular motion of Au NCs,and enlarges the proportion of excited state energy dissipated through vibrational relaxation.This result conflicts with the restriction of intramolecular motion mechanism of aggregation-induced emission.Further experiments show that the increased energy of AEPA originates from the aggregation inhibiting the intermolecular energy transfer from excited Au NCs to their surrounding medium molecules,including solvent molecule and dissolved oxygen,rather than restricting radiative relaxations.This study develops a new strategy for enhancing the PA intensity of Au NCs,and contributes to a deeper understanding of the origin of the PA signal and the excited state energy dissipation processes for MNCs.
