A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions (0.28≤x≤1.00). The morphological and structural characterization of these c...A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions (0.28≤x≤1.00). The morphological and structural characterization of these catalysts were carried out with X-ray diffraction, trans- mission electron microscopy (TEM) analysis and physical adsorption technique, and their redox properties were studied by temperature programmed reduction using both H2 and CO as probe molecules. Two cycles of oxidation/reduction were carried out in order to evaluate the effects of redox aging and gold sintering on the oxygen exchange capability. As observed with other noble metals, gold enhanced and promoted the ceria reduction at lower temperatures. Reduction by CO was shown to be dependent on the fine dispersion of gold and to be nega- tively affected by the ageing process more than reduction with hydrogen. This might have implications in reactions like water gas shift and CO-PROX which involve CO as a main reactant.展开更多
Silica supported gold nanoparticles were synthesized and promoted by lanthanum oxide as dopant. The influences of LaOand silica textural structure on the gold dispersion, formation of active species, crystalline compo...Silica supported gold nanoparticles were synthesized and promoted by lanthanum oxide as dopant. The influences of LaOand silica textural structure on the gold dispersion, formation of active species, crystalline composition and the reacting role of dopants were studied in detail. The characterization results suggested that the dispersion of gold nanoparticles depended on the textural structure of silica without lanthanum oxide doping where small mesopores are more preferable to disperse gold nanoparticles. The addition of lanthanum oxide largely increased the dispersion of gold nanoparticles and oxygen active sites independent of the textural structure of silica support. The interaction between lanthanum oxide and silica enhanced by the synergy facilitated the release of oxygen vacancies and transition of active oxygen species. In addition, the chemical properties were greatly changed after lanthanum oxide addition which was only inconspicuously impacted by the initial textural structure of silica supports, shedding light on the further design of economic gold catalyst based on simple synthesis method.展开更多
In recent years,gold nanoparticles have demonstrated excellent enzyme-mimicking activities which resemble those of peroxidase,oxidase,catalase,superoxide dismutase or reductase.This,merged with their ease of synthesis...In recent years,gold nanoparticles have demonstrated excellent enzyme-mimicking activities which resemble those of peroxidase,oxidase,catalase,superoxide dismutase or reductase.This,merged with their ease of synthesis,tunability,biocompatibility and low cost,makes them excellent candidates when compared with biological enzymes for applications in biomedicine or biochemical analyses.Herein,over 200 research papers have been systematically reviewed to present the recent progress on the fundamentals of gold nanozymes and their potential applications.The review reveals that the morphology and surface chemistry of the nanoparticles play an important role in their catalytic properties,as well as external parameters such as pH or temperature.Yet,real applications often require specific biorecognition elements to be immobilized onto the nanozymes,leading to unexpected positive or negative effects on their activity.Thus,rational design of efficient nanozymes remains a challenge of paramount importance.Different implementation paths have already been explored,including the application of peroxidase-like nanozymes for the development of clinical diagnostics or the regulation of oxidative stress within cells via their catalase and superoxide dismutase activities.The review also indicates that it is essential to understand how external parameters may boost or inhibit each of these activities,as more than one of them could coexist.Likewise,further toxicity studies are required to ensure the applicability of gold nanozymes in vivo.Current challenges and future prospects of gold nanozymes are discussed in this review,whose significance can be anticipated in a diverse range of fields beyond biomedicine,such as food safety,environmental analyses or the chemical industry.展开更多
Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-4-VPy)) microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate (EGDMA) ...Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-4-VPy)) microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate (EGDMA) and 4-vinylpyridine (4-VPy) with 2,2'-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile. The polymer microspheres containing pyridyl group were then utilized as stabilizer for gold metallic colloids with the diameter around 7 nm, which were prepared by the in situ reduction of gold chloride trihydrate with sodium borohydride through the coordination of the pyridyl group on the gel layer and surface of the microsphere with the gold metallic nano-particles. The catalytic properties of the pyridyl- functionalized microsphere-stabilized gold metallic colloids and the behavior of the stabilized-catalyst for the recycling were investigated with reduction of 4-nitrophenol to 4-aminophenol as a model reaction.展开更多
The gold ion modified TiO2 was prepared by means of sol-gel whereas gold deposited TiO2 was prepared by means of photoreduction. The physical properties were influenced significantly by the presence of gold ion or gol...The gold ion modified TiO2 was prepared by means of sol-gel whereas gold deposited TiO2 was prepared by means of photoreduction. The physical properties were influenced significantly by the presence of gold ion or gold. The enhanced photo-activity of gold modified TiO2 vas quantified in terms of methylene blue degradation. The presence of gold ion in TiO2 lattices or gold on TiO2 surface enhanced their-photo-activity. The optimum molar content of gold ion doping and gold deposition all was 0.5%. The first-order rates constants of gold modified TiO2 was more than that of pure TiO2, and decreased by increasing the content of gold ion and gold when their contents were more than 0.5%. Gold ion doped in TiO2 lattices was more effective to enhance the photo-activity than gold on TiO2 surface. Moreover, the relationship between physical properties, chemical properties and photo-activity has been discussed.展开更多
27 January 2014San Francisco,CA,USA-The International Council of Ophthalmology(ICO)Board of Trustees is pleased to announce the selection of Richard L.Abbott,MD,as the 2014 International Duke Elder medalist.The Duke E...27 January 2014San Francisco,CA,USA-The International Council of Ophthalmology(ICO)Board of Trustees is pleased to announce the selection of Richard L.Abbott,MD,as the 2014 International Duke Elder medalist.The Duke Elder Medal is awarded every four years to an ophthalmologist who,by his/her distinction,leadership,and teaching,has contributed most to the development of international relations and friendship between ophthalmologists,and who has advanced the field by his/her contributions in writing and organization in ophthalmology.展开更多
In this paper, we describe a simple and efficient synthesis of gold nanoparticles(GNPs) of various shapes(spherical, rod-like, hexagonal, truncated triangular, and triangular) using Au(Ⅲ) reduction in aqueous solutio...In this paper, we describe a simple and efficient synthesis of gold nanoparticles(GNPs) of various shapes(spherical, rod-like, hexagonal, truncated triangular, and triangular) using Au(Ⅲ) reduction in aqueous solutions by L-tryptophan. We evaluated the influences of reaction temperature, foreign metal ions Ag(Ⅰ), and surfactants of nonionic(polyethylene glycol, PEG), anionic(sodium dodecyl sulfate, SDS), and cationic(cetyltrimethyl ammonium bromide, CTAB) on GNPs synthesis. We characterized the resultant GNPs using UV–visible adsorption spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, selected-area electron diffraction, and Fourier-transform infrared spectroscopy. We fabricated the variously sized GNPs by controlling the rate of the reduction of gold ions in aqueous solution by varying the reaction temperature: the higher the temperature, the smaller the gold nanospheres. We found the existence of Ag(Ⅰ) to reinforce the reduction of Au(Ⅲ) and to correspond with the appearance of some amorphous bimetallic Au/Ag nanoparticles. Additionally, we found the presence of surfactants to greatly influence the shape of the formed GNPs, especially the presence of CTAB, which results in the anisotropic growth of gold nanocrystals into hexagonal, truncated triangular, and triangular nanoplates. In addition, with the increase in CTAB concentration, we found the amount of gold nanoplates to first increase and then decrease. Finally, we performed preliminary explorations of the reduction process and morphological evolution to propose possible corresponding reduction and morphological evolution pathways.展开更多
This study focuses on shape-controlled synthesis of gold nanoparticles, using the green reducing agent L-Tryptophan(L-Trp), which is non-toxic and eco-friendly. This specific agent was investigated to realize certain ...This study focuses on shape-controlled synthesis of gold nanoparticles, using the green reducing agent L-Tryptophan(L-Trp), which is non-toxic and eco-friendly. This specific agent was investigated to realize certain morphology controlling effects by changing the relative growth rates among various crystal planes. Experimental samples were characterized by transmission electron microscope, UV-Vis spectrophotometer and X-ray diffraction(XRD) for size and morphological information. The effects of the specific additives of PVP((C_6 H_9 NO)_n), CTAB(C_(16)H_(33)(CH_3)_3 NBr), and KBr were examined for their morphological control individually and synergistically in this system. Hexagonal gold nanoparticles were successfully obtained via the PVP/CTAB and PVP/KBr systems. Particular amounts of PVP/KBr produced various polyhedron structures, such as cubes, and others with triangular and rhombic straight-side cross sections.展开更多
文摘A series of gold-based catalysts were prepared by deposition precipitation or incipient wetness impregnation on CexZ1-xO2 solid solutions (0.28≤x≤1.00). The morphological and structural characterization of these catalysts were carried out with X-ray diffraction, trans- mission electron microscopy (TEM) analysis and physical adsorption technique, and their redox properties were studied by temperature programmed reduction using both H2 and CO as probe molecules. Two cycles of oxidation/reduction were carried out in order to evaluate the effects of redox aging and gold sintering on the oxygen exchange capability. As observed with other noble metals, gold enhanced and promoted the ceria reduction at lower temperatures. Reduction by CO was shown to be dependent on the fine dispersion of gold and to be nega- tively affected by the ageing process more than reduction with hydrogen. This might have implications in reactions like water gas shift and CO-PROX which involve CO as a main reactant.
基金supported by the foundation of programme from Education Department of Sichuan (15ZA0303)New Century Excellent Talent Project of China (NCET-05-0783)
文摘Silica supported gold nanoparticles were synthesized and promoted by lanthanum oxide as dopant. The influences of LaOand silica textural structure on the gold dispersion, formation of active species, crystalline composition and the reacting role of dopants were studied in detail. The characterization results suggested that the dispersion of gold nanoparticles depended on the textural structure of silica without lanthanum oxide doping where small mesopores are more preferable to disperse gold nanoparticles. The addition of lanthanum oxide largely increased the dispersion of gold nanoparticles and oxygen active sites independent of the textural structure of silica support. The interaction between lanthanum oxide and silica enhanced by the synergy facilitated the release of oxygen vacancies and transition of active oxygen species. In addition, the chemical properties were greatly changed after lanthanum oxide addition which was only inconspicuously impacted by the initial textural structure of silica supports, shedding light on the further design of economic gold catalyst based on simple synthesis method.
基金The authors J.L.,C.E.and C.C.acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No.720325.B.D.and C.C.thank the support from the Commonwealth Split-site Scholarship.
文摘In recent years,gold nanoparticles have demonstrated excellent enzyme-mimicking activities which resemble those of peroxidase,oxidase,catalase,superoxide dismutase or reductase.This,merged with their ease of synthesis,tunability,biocompatibility and low cost,makes them excellent candidates when compared with biological enzymes for applications in biomedicine or biochemical analyses.Herein,over 200 research papers have been systematically reviewed to present the recent progress on the fundamentals of gold nanozymes and their potential applications.The review reveals that the morphology and surface chemistry of the nanoparticles play an important role in their catalytic properties,as well as external parameters such as pH or temperature.Yet,real applications often require specific biorecognition elements to be immobilized onto the nanozymes,leading to unexpected positive or negative effects on their activity.Thus,rational design of efficient nanozymes remains a challenge of paramount importance.Different implementation paths have already been explored,including the application of peroxidase-like nanozymes for the development of clinical diagnostics or the regulation of oxidative stress within cells via their catalase and superoxide dismutase activities.The review also indicates that it is essential to understand how external parameters may boost or inhibit each of these activities,as more than one of them could coexist.Likewise,further toxicity studies are required to ensure the applicability of gold nanozymes in vivo.Current challenges and future prospects of gold nanozymes are discussed in this review,whose significance can be anticipated in a diverse range of fields beyond biomedicine,such as food safety,environmental analyses or the chemical industry.
基金This work was supported in part by the National Science Foundation of China(No.20504015)the Opening Research Fund from the State Key Laboratory of Polymer Chemistry and Physics,Chinese Academy of Sciences(No.200613).
文摘Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-4-VPy)) microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate (EGDMA) and 4-vinylpyridine (4-VPy) with 2,2'-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile. The polymer microspheres containing pyridyl group were then utilized as stabilizer for gold metallic colloids with the diameter around 7 nm, which were prepared by the in situ reduction of gold chloride trihydrate with sodium borohydride through the coordination of the pyridyl group on the gel layer and surface of the microsphere with the gold metallic nano-particles. The catalytic properties of the pyridyl- functionalized microsphere-stabilized gold metallic colloids and the behavior of the stabilized-catalyst for the recycling were investigated with reduction of 4-nitrophenol to 4-aminophenol as a model reaction.
基金Guangdong Natural Science Foundation (No .980 0 12 )
文摘The gold ion modified TiO2 was prepared by means of sol-gel whereas gold deposited TiO2 was prepared by means of photoreduction. The physical properties were influenced significantly by the presence of gold ion or gold. The enhanced photo-activity of gold modified TiO2 vas quantified in terms of methylene blue degradation. The presence of gold ion in TiO2 lattices or gold on TiO2 surface enhanced their-photo-activity. The optimum molar content of gold ion doping and gold deposition all was 0.5%. The first-order rates constants of gold modified TiO2 was more than that of pure TiO2, and decreased by increasing the content of gold ion and gold when their contents were more than 0.5%. Gold ion doped in TiO2 lattices was more effective to enhance the photo-activity than gold on TiO2 surface. Moreover, the relationship between physical properties, chemical properties and photo-activity has been discussed.
文摘27 January 2014San Francisco,CA,USA-The International Council of Ophthalmology(ICO)Board of Trustees is pleased to announce the selection of Richard L.Abbott,MD,as the 2014 International Duke Elder medalist.The Duke Elder Medal is awarded every four years to an ophthalmologist who,by his/her distinction,leadership,and teaching,has contributed most to the development of international relations and friendship between ophthalmologists,and who has advanced the field by his/her contributions in writing and organization in ophthalmology.
基金supported by the Independent Innovation Foundation of Tianjin University (No. 2016XZC-0028)
文摘In this paper, we describe a simple and efficient synthesis of gold nanoparticles(GNPs) of various shapes(spherical, rod-like, hexagonal, truncated triangular, and triangular) using Au(Ⅲ) reduction in aqueous solutions by L-tryptophan. We evaluated the influences of reaction temperature, foreign metal ions Ag(Ⅰ), and surfactants of nonionic(polyethylene glycol, PEG), anionic(sodium dodecyl sulfate, SDS), and cationic(cetyltrimethyl ammonium bromide, CTAB) on GNPs synthesis. We characterized the resultant GNPs using UV–visible adsorption spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, selected-area electron diffraction, and Fourier-transform infrared spectroscopy. We fabricated the variously sized GNPs by controlling the rate of the reduction of gold ions in aqueous solution by varying the reaction temperature: the higher the temperature, the smaller the gold nanospheres. We found the existence of Ag(Ⅰ) to reinforce the reduction of Au(Ⅲ) and to correspond with the appearance of some amorphous bimetallic Au/Ag nanoparticles. Additionally, we found the presence of surfactants to greatly influence the shape of the formed GNPs, especially the presence of CTAB, which results in the anisotropic growth of gold nanocrystals into hexagonal, truncated triangular, and triangular nanoplates. In addition, with the increase in CTAB concentration, we found the amount of gold nanoplates to first increase and then decrease. Finally, we performed preliminary explorations of the reduction process and morphological evolution to propose possible corresponding reduction and morphological evolution pathways.
基金supported by the Independent Innovation Foundation of Tianjin University (No.2016XZC-0028)
文摘This study focuses on shape-controlled synthesis of gold nanoparticles, using the green reducing agent L-Tryptophan(L-Trp), which is non-toxic and eco-friendly. This specific agent was investigated to realize certain morphology controlling effects by changing the relative growth rates among various crystal planes. Experimental samples were characterized by transmission electron microscope, UV-Vis spectrophotometer and X-ray diffraction(XRD) for size and morphological information. The effects of the specific additives of PVP((C_6 H_9 NO)_n), CTAB(C_(16)H_(33)(CH_3)_3 NBr), and KBr were examined for their morphological control individually and synergistically in this system. Hexagonal gold nanoparticles were successfully obtained via the PVP/CTAB and PVP/KBr systems. Particular amounts of PVP/KBr produced various polyhedron structures, such as cubes, and others with triangular and rhombic straight-side cross sections.