Gold（Au） nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first tim...Gold（Au） nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first time the support shape effect on the catalysis of Au nanoclusters by using CO oxidation as a model reaction. Au22（L8）6（L = 1,8-bis（diphenylphosphino） octane） nanoclusters were supported on CeO2 rods or cubes, then pretreated at different temperatures（up to 673 K）, allowing the gradual removal of the organic phosphine ligands. CO oxidation test over these differently pretreated samples shows that CeO2 rods are much better supports than cubes for Au22 nanoclusters in enhancing the reaction rate. In situ IR spectroscopy coupled with CO adsorption indicates that the shape of CeO2 support can impact the nature and quantity of exposed Au sites, as well as the efficiency of organic ligand removal. Although CeO2 rods are helpful in exposing a greater percentage of total Au sites upon ligands removal, the percentage of active Au sites（denoted by Au d＋, 0 〈 d 〈 1） is lower than that on CeO2 cubes. The in situ extended X-ray absorption spectroscopy（EXAFS） and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM） results show that the Au nanoclusters bound more strongly to the CeO2 rods than to the cubes where the Au nanoclusters show more sintering. Considering the typical redox mechanism for CO oxidation over supported Au nanoclusters and nanoparticles, it is concluded that the reactivity of the lattice oxygen of CeO2 is the determining factor for CO oxidation over Au22/CeO2. CeO2 rods offer more reactive lattice oxygen and abundant oxygen vacancies than the cubes and thus make the rods a superior support for Au nanoclusters in catalyzing low temperature CO oxidation.展开更多
Heteroatom dopants can greatly modify the electronic and physical properties and catalytic performance of gold nanoclusters. In this study, we investigate the catalytic activity of [Au25-x（PET）18-xM]NH3 （PET = 2-ph...Heteroatom dopants can greatly modify the electronic and physical properties and catalytic performance of gold nanoclusters. In this study, we investigate the catalytic activity of [Au25-x（PET）18-xM]NH3 （PET = 2-phenylethanethiolate, and M = Cu, Co, Ni, and Zn） nanoclusters in aerobic alcohol oxidation. The [Au25-xPET）18-xM]NH3 nanoclusters are thoroughly characterized by matrix assisted laser desorption ionization （MALDI） mass spectrometry, X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectroscopy （FT-IR）, and inductively coupled plasma-mass spectrometry （ICP-MS）. The XPS analyses suggest that the transition metals strongly interact with the gold atoms of the nanoclusters. The CeO2-supported nanoclusters show catalytic activity, based on the conversion of benzyl alcohol, in the order, [Au25-x（PET）18-xNi] 〉 [Au25-x（PET）18-xCu] 〉 [Au25-x（PET）18-xZn] 〉 [Au25-x（PET）18-xCo]. Regarding product selectivity, the [Au25-xPET）18-xZn] and [Au25-x（PET）18-xCo] catalysts preferably yield benzaldehyde, [Au25-x（PET）18-xCu] yields benzaldehyde and benzyl acid, and [Au25-x（PET）18-xNi] yields benzyl acid. The exposed metal atoms are considered as the catalytic active sites. Also, the catalytic performance （including activity and selectivity） of the [Au25-x（PET）18-xM] catalysts is greatly turned and mediated by the transition metal type.展开更多
The use of near-infrared （NIR） light for photodynamic therapy （PDT） is a promising strategy to circumvent the limitations of current PDT, in which visible light with limited tissue penetration depth is usually use...The use of near-infrared （NIR） light for photodynamic therapy （PDT） is a promising strategy to circumvent the limitations of current PDT, in which visible light with limited tissue penetration depth is usually used. In the present stud~ alkyl thiolated gold nanoclusters （AuNCs） were co-modified with human serum albumin （HSA） and catalase （CAT）, and then employed as a multifunctional, optical, theranostic nano-agent. In the AuNC@HSA/CAT system, the AuNCs were able to produce singlet oxygen under excitation by a 1,064-nm laser, which locates in the second NIR window （NIR-II）, and featured much lower tissue absorption and scattering, enabling NIR-II-triggered PDT. The HSA coating greatly improved the physiological stability of the nanoparticles, which showed efficient tumor retention after intravenous injection, as revealed by detecting the AuNC fluorescence. Moreover, the presence of CAT in the nanoparticles triggered decomposition of tumor endogenous H202 to generate oxygen, thereby enhancing the efficacy of PDT by relieving tumor hypoxia. Compared with conventional PDT using visible light, NIR-II-triggered PDT exhibits remarkably increased tissue penetration. Thus, we developed a new type of photosensitizing nano-agent that simultaneously enables in vivo fluorescence imaging, tumor hypoxia relief, and NIR-II light-induced in vivo PDT in the treatment of cancer.展开更多
基金supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Divisionsupported by the U.S. Department of Energy, Office of Science, Office of Basic Energy, Sciences under Contract No. DE-AC02-76SF00515the facilities support at the beamline BL 2-2 provided by the Synchrotron Catalysis Consortium U.S. DOE (No. De-SC0012335)
文摘Gold（Au） nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first time the support shape effect on the catalysis of Au nanoclusters by using CO oxidation as a model reaction. Au22（L8）6（L = 1,8-bis（diphenylphosphino） octane） nanoclusters were supported on CeO2 rods or cubes, then pretreated at different temperatures（up to 673 K）, allowing the gradual removal of the organic phosphine ligands. CO oxidation test over these differently pretreated samples shows that CeO2 rods are much better supports than cubes for Au22 nanoclusters in enhancing the reaction rate. In situ IR spectroscopy coupled with CO adsorption indicates that the shape of CeO2 support can impact the nature and quantity of exposed Au sites, as well as the efficiency of organic ligand removal. Although CeO2 rods are helpful in exposing a greater percentage of total Au sites upon ligands removal, the percentage of active Au sites（denoted by Au d＋, 0 〈 d 〈 1） is lower than that on CeO2 cubes. The in situ extended X-ray absorption spectroscopy（EXAFS） and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM） results show that the Au nanoclusters bound more strongly to the CeO2 rods than to the cubes where the Au nanoclusters show more sintering. Considering the typical redox mechanism for CO oxidation over supported Au nanoclusters and nanoparticles, it is concluded that the reactivity of the lattice oxygen of CeO2 is the determining factor for CO oxidation over Au22/CeO2. CeO2 rods offer more reactive lattice oxygen and abundant oxygen vacancies than the cubes and thus make the rods a superior support for Au nanoclusters in catalyzing low temperature CO oxidation.
文摘Heteroatom dopants can greatly modify the electronic and physical properties and catalytic performance of gold nanoclusters. In this study, we investigate the catalytic activity of [Au25-x（PET）18-xM]NH3 （PET = 2-phenylethanethiolate, and M = Cu, Co, Ni, and Zn） nanoclusters in aerobic alcohol oxidation. The [Au25-xPET）18-xM]NH3 nanoclusters are thoroughly characterized by matrix assisted laser desorption ionization （MALDI） mass spectrometry, X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectroscopy （FT-IR）, and inductively coupled plasma-mass spectrometry （ICP-MS）. The XPS analyses suggest that the transition metals strongly interact with the gold atoms of the nanoclusters. The CeO2-supported nanoclusters show catalytic activity, based on the conversion of benzyl alcohol, in the order, [Au25-x（PET）18-xNi] 〉 [Au25-x（PET）18-xCu] 〉 [Au25-x（PET）18-xZn] 〉 [Au25-x（PET）18-xCo]. Regarding product selectivity, the [Au25-xPET）18-xZn] and [Au25-x（PET）18-xCo] catalysts preferably yield benzaldehyde, [Au25-x（PET）18-xCu] yields benzaldehyde and benzyl acid, and [Au25-x（PET）18-xNi] yields benzyl acid. The exposed metal atoms are considered as the catalytic active sites. Also, the catalytic performance （including activity and selectivity） of the [Au25-x（PET）18-xM] catalysts is greatly turned and mediated by the transition metal type.
基金This article was partially supported by the National Basic Research Programs of China （973 Program） （No. 2016YFA0201200）, the National Natural Science Foundation of China （No. 51525203）, Collaborative Innovation Center of Suzhou Nano Science and Technology, and a Project Funded by the Priority Academic Program Development （PAPD） of Jiangsu Higher Education Institutions.
文摘The use of near-infrared （NIR） light for photodynamic therapy （PDT） is a promising strategy to circumvent the limitations of current PDT, in which visible light with limited tissue penetration depth is usually used. In the present stud~ alkyl thiolated gold nanoclusters （AuNCs） were co-modified with human serum albumin （HSA） and catalase （CAT）, and then employed as a multifunctional, optical, theranostic nano-agent. In the AuNC@HSA/CAT system, the AuNCs were able to produce singlet oxygen under excitation by a 1,064-nm laser, which locates in the second NIR window （NIR-II）, and featured much lower tissue absorption and scattering, enabling NIR-II-triggered PDT. The HSA coating greatly improved the physiological stability of the nanoparticles, which showed efficient tumor retention after intravenous injection, as revealed by detecting the AuNC fluorescence. Moreover, the presence of CAT in the nanoparticles triggered decomposition of tumor endogenous H202 to generate oxygen, thereby enhancing the efficacy of PDT by relieving tumor hypoxia. Compared with conventional PDT using visible light, NIR-II-triggered PDT exhibits remarkably increased tissue penetration. Thus, we developed a new type of photosensitizing nano-agent that simultaneously enables in vivo fluorescence imaging, tumor hypoxia relief, and NIR-II light-induced in vivo PDT in the treatment of cancer.
基金This work was supported by the National Natural Science Foundation of China(No.21973022)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012353).
