Two types of CeO2 nanocubes （average size of 5 and 20 nm, respectively） prepared via the hydrothermal process were selected to load gold species via a deposition-precipitation （DP） method. Various measurements, in...Two types of CeO2 nanocubes （average size of 5 and 20 nm, respectively） prepared via the hydrothermal process were selected to load gold species via a deposition-precipitation （DP） method. Various measurements, including X-ray diffraction （XRD）, Raman spectra, high resolution transmission electron microscopy （HRTEM）, in situ diffuse reflectance infrared Fourier transform spectroscopy （in situ DRIFTS）, and temperature-programmed reduction by hydrogen （H2-TPR）, were applied to characterize the catalysts. It is found that the sample with ceria size of 20 nm （Au/CeO2-20） was covered by well dis ersed both Au^3＋ and Au^δ＋ （0〈δ〈1）. For the other sample with ceria size of 5 nm （Au/CEO2-5）, Au^3＋ is the dominant gold species. Au/CeO2-20 performed better catalytic activity for CO oxidation because of the strong CO adsorption of Au^δ＋ in the catalysts. The catalytic activity of Au/CeO2-5 was improved due to the transformation of Au^3＋ to Au^δ＋. Based on the CO oxidation and in situ DRIFTS results, Au^δ＋ is likely to play a more important role in catalyzing CO oxidation reaction.展开更多
Ceria nanoparticles were facilely synthesized by a molten NaOH-KOH hydroxide flux method with the precursor of Ce(NO3)3·6H2O under different conditions in alumina crucibles or Teflon-lined stainless steel autocla...Ceria nanoparticles were facilely synthesized by a molten NaOH-KOH hydroxide flux method with the precursor of Ce(NO3)3·6H2O under different conditions in alumina crucibles or Teflon-lined stainless steel autoclave.The XRD patterns and TEM images show that both the crystal and particle sizes of synthesized nanoceria are around 10 nm.XPS results reveal that the nanoceria obtained in alumina crucible has a Ce3+fraction of 17.1%which is higher than that of ceria synthesized in the Teflon vessel,the FTIR spectra of nanoceria prepared in alumina crucible show a stronger intensity of O-H stretching mode.UV-DRS and PL spectra results show that the nanoceria synthesized in alumina crucible with a calculated band gap of 2.9 eV has a wider responding light wavelength and a lower photogene rated electron-hole recombination rate,due to a higher concentration of oxygen vacancies(Ce^3+%).The photocatalytic results show that the degradation ratio and rate of the Rhodamine B(RhB)solution with the nanoceria synthesized in alumina crucible are 98.39%and 0.02919 min-1,both of which are larger than those of the ceria obtained from Teflon vessel.This method proves to be a simple and scalable way to synthesize nanoceria with rich oxygen vacancies and high photocatalytic activity.展开更多
Ceria is widely used as a catalyst for soot combustion,but effects of Zr substitution on the reaction mechanism is ambiguous.The present work elucidates effects of Zr substitution on soot combustion over cubic fluorit...Ceria is widely used as a catalyst for soot combustion,but effects of Zr substitution on the reaction mechanism is ambiguous.The present work elucidates effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria.The nanostructured CeO_(2),Ce_(0.92)Zr_(0.08)O_(2),and Ce_(0.84)Zr_(0.16)O_(2)composed of 5-6 nm crystallites display T_(m-CO2)(the temperature at maximum CO_2 yield)at 383,355,and 375℃under 10 vol.%O_(2)/N_(2),respectively.The size of agglomerate decreases from 165.5 to 51.9-57.3 nm,which is beneficial for the sootceria contact.Moreover,Zr increases the amount of surface oxygen vacancies,generating more active oxygen(O_(2)^-and O^(-))for soot oxidation.Thus,the activities of Ce_(0.92)Zr_(0.08)O_(2)and Ce_(0.84)Zr_(0.16)O_(2)in soot combustion are better than that of CeO_(2).Although oxygen vacancies promote the migration of lattice O~(2-),the enriched surface Zr also inhibits the mobility of lattice O^(2-).Therefore,the T_(m-CO2)of Ce_(0.84)Zr_(0.1)6 O_(2)is higher than that of Ce_(0.92)Zr_(0.08)O_(2).Based on reaction kinetic study,soot in direct contact with ceria preferentially decomposes with low activation energy,while the oxidation of isolated soot occurs through diffusion with high activation energy.The obtained findings provide new understanding on the soot combustion over nanoceria.展开更多
Central nervous system(CNS)injury,induced by ischemic/hemorrhagic or traumatic damage,is one of the most common causes of death and long-term disability worldwide.Reactive oxygen and nitrogen species(RONS)resulting in...Central nervous system(CNS)injury,induced by ischemic/hemorrhagic or traumatic damage,is one of the most common causes of death and long-term disability worldwide.Reactive oxygen and nitrogen species(RONS)resulting in oxidative/nitrosative stress play a critical role in the pathological cascade of molecular events after CNS injury.Therefore,by targeting RONS,antioxidant therapies have been intensively explored in previous studies.However,traditional antioxidants have achieved limited success thus far,and the development of new antioxidants to achieve highly effective RONS modulation in CNS injury still remains a great challenge.With the rapid development of nanotechnology,novel nanomaterials provided promising opportunities to address this challenge.Within these,nanoceria has gained much attention due to its regenerative and excellent RONS elimination capability.To promote its practical application,it is important to know what has been done and what has yet to be done.This review aims to present the opportunities and challenges of nanoceria in treating CNS injury.The physicochemical properties of nanoceria and its interaction with RONS are described.The applications of nanoceria for stroke and neurotrauma treatment are summarized.The possible directions for future application of nanoceria in CNS injury treatment are proposed.展开更多
The authors studied dispersing behavior of a nanoceria abrasive under joint actions of mechanical ultra-sonication and chemical dispersants,to explore effective approaches and methods for dispersing it and manifesting...The authors studied dispersing behavior of a nanoceria abrasive under joint actions of mechanical ultra-sonication and chemical dispersants,to explore effective approaches and methods for dispersing it and manifesting its functions of nanometric scale.It was found that mechanical ultra-sonication solely could not disperse the nanoceria abrasive effectively,while dispersants such as sodium hexametaphosphate(SHP) and sodium dodecylbenzenesulfonate(SDBS) could help to disperse the nanoceria abrasive.SHP and SDBS were found to increase value of zeta potential of the nanoceria abrasive markedly and decrease level of apparent viscosity of its slurry observably.It was deduced by analysis that the dispersants increased inter-particles mutual repulsive force by forming steric hindrance between particles and augmenting zeta potential of particle surfaces,which could overcome van der Waals attracting force to some extent,reduce agglomeration and flocculation of the nanoceria particles,thus improve dispersibility and stability of the nanoceria particles in slurries.展开更多
Nanotechnology offers exciting new approaches for biology and medicine. In recent years, nanoparticles,particularly those of the rare metal cerium, are showing potential for a wide range of applications in medicine.Ce...Nanotechnology offers exciting new approaches for biology and medicine. In recent years, nanoparticles,particularly those of the rare metal cerium, are showing potential for a wide range of applications in medicine.Cerium oxide nanoparticles or nanoceria are antioxidants and possess catalytic activities that mimic those of super oxide dismutase and catalase, thereby protecting cellsfrom oxidative stress. The retina is highly susceptible to oxidative stress because of its high oxygen consumption and high metabolic activity associated with exposure to light. Many retinal diseases progress through oxidative stress as a result of a chronic or acute rise in reactive oxygen species. Diseases of the retina are the leading causes of blindness throughout the world. Although some treatments may delay or slow the development of retinal diseases, there are no cures for most forms of blinding diseases. In this review is summarized evidence that cerium oxide nanoparticles can function as catalytic antioxidants in vivo in rodent models of age-related macular degeneration and inherited retinal degeneration and may represent a novel therapeutic strategy for the treatment of human eye diseases. This may shift current research and clinical practice towards the use of nanoceria, alone or in combination with other therapeutics.展开更多
In the past decades, enzyme mimetics based on ceria nanoparticles （nanoceria） have been developed as potential substitutes for nature enzymes. The mixed valence states of cerium and the patterns of oxygen vacancies ...In the past decades, enzyme mimetics based on ceria nanoparticles （nanoceria） have been developed as potential substitutes for nature enzymes. The mixed valence states of cerium and the patterns of oxygen vacancies on crystal planes result in different enzyme mimetic activities. In this review we survey the bio-applications of nanoceria-based enzyme mimetics as well as the underlying mechanisms. Factors influencing the enzyme mimetic activities and future perspective of nanoceria-based enzyme mimetics are also addressed.展开更多
Ca^(2+)plays critical roles in the development of diseases,whereas existing various Ca regulation methods have been greatly restricted in their clinical applications due to their high toxicity and inefficiency.To solv...Ca^(2+)plays critical roles in the development of diseases,whereas existing various Ca regulation methods have been greatly restricted in their clinical applications due to their high toxicity and inefficiency.To solve this issue,with the help of Ca overexpressed tumor drug resistance model,the phytic acid(PA)-modified CeO_(2) nano-inhibitors have been rationally designed as an unprecedentedly safe and efficient Ca2+inhibitor to successfully reverse tumor drug resistance through Ca^(2+)negative regulation strategy.Using doxorubicin(Dox)as a model chemotherapeutic drug,the Ca^(2+)nano-inhibitors efficiently deprived intracellular excessive free Ca2+,suppressed P-glycoprotein(P-gp)expression and significantly enhanced intracellular drug accumulation in Dox-resistant tumor cells.This Ca^(2+)negative regulation strategy improved the intratumoral Dox concentration by a factor of 12.4 and nearly eradicated tumors without obvious adverse effects.Besides,nanocerias as pH-regulated nanozyme greatly alleviated the adverse effects of chemotherapeutic drug on normal cells/organs and substantially improved survivals of mice.We anticipate that this safe and effective Ca^(2+)negative regulation strategy has potentials to conquer the pitfalls of traditional Ca inhibitors,improve therapeutic efficacy of common chemotherapeutic drugs and serves as a facile and effective treatment platform of other Ca^(2+) associated diseases.展开更多
基金Financial support was given from the National Science Foundation of China （NSFC） （Nos. 21501109, 21771117）, the Excellent Young Scientists Fund from NSFC （No. 21622106）, the Science Fund for Distinguished Young Scholars of Shandong Province of China （No. JQ201703）, and the Taishan Scholar Project of Shandong Province of China.
文摘Two types of CeO2 nanocubes （average size of 5 and 20 nm, respectively） prepared via the hydrothermal process were selected to load gold species via a deposition-precipitation （DP） method. Various measurements, including X-ray diffraction （XRD）, Raman spectra, high resolution transmission electron microscopy （HRTEM）, in situ diffuse reflectance infrared Fourier transform spectroscopy （in situ DRIFTS）, and temperature-programmed reduction by hydrogen （H2-TPR）, were applied to characterize the catalysts. It is found that the sample with ceria size of 20 nm （Au/CeO2-20） was covered by well dis ersed both Au^3＋ and Au^δ＋ （0〈δ〈1）. For the other sample with ceria size of 5 nm （Au/CEO2-5）, Au^3＋ is the dominant gold species. Au/CeO2-20 performed better catalytic activity for CO oxidation because of the strong CO adsorption of Au^δ＋ in the catalysts. The catalytic activity of Au/CeO2-5 was improved due to the transformation of Au^3＋ to Au^δ＋. Based on the CO oxidation and in situ DRIFTS results, Au^δ＋ is likely to play a more important role in catalyzing CO oxidation reaction.
基金Project supported by National Natural Science Foundation of China(51804088)the Talents&Platform Funding from Science&Technology Department of Guizhou Province([2017]5788,[2018]5781)+1 种基金the Basic Research Program from Science&Technology Department of Guizhou Province([2019]1082)the Doctor Funding of Guizhou University((2017)04)。
文摘Ceria nanoparticles were facilely synthesized by a molten NaOH-KOH hydroxide flux method with the precursor of Ce(NO3)3·6H2O under different conditions in alumina crucibles or Teflon-lined stainless steel autoclave.The XRD patterns and TEM images show that both the crystal and particle sizes of synthesized nanoceria are around 10 nm.XPS results reveal that the nanoceria obtained in alumina crucible has a Ce3+fraction of 17.1%which is higher than that of ceria synthesized in the Teflon vessel,the FTIR spectra of nanoceria prepared in alumina crucible show a stronger intensity of O-H stretching mode.UV-DRS and PL spectra results show that the nanoceria synthesized in alumina crucible with a calculated band gap of 2.9 eV has a wider responding light wavelength and a lower photogene rated electron-hole recombination rate,due to a higher concentration of oxygen vacancies(Ce^3+%).The photocatalytic results show that the degradation ratio and rate of the Rhodamine B(RhB)solution with the nanoceria synthesized in alumina crucible are 98.39%and 0.02919 min-1,both of which are larger than those of the ceria obtained from Teflon vessel.This method proves to be a simple and scalable way to synthesize nanoceria with rich oxygen vacancies and high photocatalytic activity.
基金financially supported by Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302013)the Natural Science Foundation for Distinguished Young Scientists of Guangdong Province(No.2020B1515020015)+1 种基金Pearl River S&T Nova Program of Guangzhou(No.201806010069)。
文摘Ceria is widely used as a catalyst for soot combustion,but effects of Zr substitution on the reaction mechanism is ambiguous.The present work elucidates effects of Zr substitution on soot combustion over cubic fluorite-structured nanoceria.The nanostructured CeO_(2),Ce_(0.92)Zr_(0.08)O_(2),and Ce_(0.84)Zr_(0.16)O_(2)composed of 5-6 nm crystallites display T_(m-CO2)(the temperature at maximum CO_2 yield)at 383,355,and 375℃under 10 vol.%O_(2)/N_(2),respectively.The size of agglomerate decreases from 165.5 to 51.9-57.3 nm,which is beneficial for the sootceria contact.Moreover,Zr increases the amount of surface oxygen vacancies,generating more active oxygen(O_(2)^-and O^(-))for soot oxidation.Thus,the activities of Ce_(0.92)Zr_(0.08)O_(2)and Ce_(0.84)Zr_(0.16)O_(2)in soot combustion are better than that of CeO_(2).Although oxygen vacancies promote the migration of lattice O~(2-),the enriched surface Zr also inhibits the mobility of lattice O^(2-).Therefore,the T_(m-CO2)of Ce_(0.84)Zr_(0.1)6 O_(2)is higher than that of Ce_(0.92)Zr_(0.08)O_(2).Based on reaction kinetic study,soot in direct contact with ceria preferentially decomposes with low activation energy,while the oxidation of isolated soot occurs through diffusion with high activation energy.The obtained findings provide new understanding on the soot combustion over nanoceria.
基金supported by the Pre-research Project(2020XYY15)of Army Medical University。
文摘Central nervous system(CNS)injury,induced by ischemic/hemorrhagic or traumatic damage,is one of the most common causes of death and long-term disability worldwide.Reactive oxygen and nitrogen species(RONS)resulting in oxidative/nitrosative stress play a critical role in the pathological cascade of molecular events after CNS injury.Therefore,by targeting RONS,antioxidant therapies have been intensively explored in previous studies.However,traditional antioxidants have achieved limited success thus far,and the development of new antioxidants to achieve highly effective RONS modulation in CNS injury still remains a great challenge.With the rapid development of nanotechnology,novel nanomaterials provided promising opportunities to address this challenge.Within these,nanoceria has gained much attention due to its regenerative and excellent RONS elimination capability.To promote its practical application,it is important to know what has been done and what has yet to be done.This review aims to present the opportunities and challenges of nanoceria in treating CNS injury.The physicochemical properties of nanoceria and its interaction with RONS are described.The applications of nanoceria for stroke and neurotrauma treatment are summarized.The possible directions for future application of nanoceria in CNS injury treatment are proposed.
基金Project supported by the Development Foundation of China Acadmy of Enginerring Physics (2009B0302035)
文摘The authors studied dispersing behavior of a nanoceria abrasive under joint actions of mechanical ultra-sonication and chemical dispersants,to explore effective approaches and methods for dispersing it and manifesting its functions of nanometric scale.It was found that mechanical ultra-sonication solely could not disperse the nanoceria abrasive effectively,while dispersants such as sodium hexametaphosphate(SHP) and sodium dodecylbenzenesulfonate(SDBS) could help to disperse the nanoceria abrasive.SHP and SDBS were found to increase value of zeta potential of the nanoceria abrasive markedly and decrease level of apparent viscosity of its slurry observably.It was deduced by analysis that the dispersants increased inter-particles mutual repulsive force by forming steric hindrance between particles and augmenting zeta potential of particle surfaces,which could overcome van der Waals attracting force to some extent,reduce agglomeration and flocculation of the nanoceria particles,thus improve dispersibility and stability of the nanoceria particles in slurries.
基金Supported by NIH NEI,No.R21EY018306,R01EY18724,R01EY022111National Science Foundation,No.CBET-0708172
文摘Nanotechnology offers exciting new approaches for biology and medicine. In recent years, nanoparticles,particularly those of the rare metal cerium, are showing potential for a wide range of applications in medicine.Cerium oxide nanoparticles or nanoceria are antioxidants and possess catalytic activities that mimic those of super oxide dismutase and catalase, thereby protecting cellsfrom oxidative stress. The retina is highly susceptible to oxidative stress because of its high oxygen consumption and high metabolic activity associated with exposure to light. Many retinal diseases progress through oxidative stress as a result of a chronic or acute rise in reactive oxygen species. Diseases of the retina are the leading causes of blindness throughout the world. Although some treatments may delay or slow the development of retinal diseases, there are no cures for most forms of blinding diseases. In this review is summarized evidence that cerium oxide nanoparticles can function as catalytic antioxidants in vivo in rodent models of age-related macular degeneration and inherited retinal degeneration and may represent a novel therapeutic strategy for the treatment of human eye diseases. This may shift current research and clinical practice towards the use of nanoceria, alone or in combination with other therapeutics.
文摘In the past decades, enzyme mimetics based on ceria nanoparticles （nanoceria） have been developed as potential substitutes for nature enzymes. The mixed valence states of cerium and the patterns of oxygen vacancies on crystal planes result in different enzyme mimetic activities. In this review we survey the bio-applications of nanoceria-based enzyme mimetics as well as the underlying mechanisms. Factors influencing the enzyme mimetic activities and future perspective of nanoceria-based enzyme mimetics are also addressed.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52002314,21872109,81802841,and 81702999)China Postdoctoral Science Foundation(Nos.2018M633504 and 2018M633749)+3 种基金The study was also supported by the National Natural Science Foundation of Shaanxi Province(No.2019JQ-486)the Natural Science Basic Research Plan in Shaanxi Province(No.2019JM-033)Technology Innovation Development Foundation of Tangdu Hospital(No.2019QYTS003)Authors also acknowledge the support from the Fundamental Research Funds for the Central Universities(Nos.D5000210829 and G2021KY05102).
文摘Ca^(2+)plays critical roles in the development of diseases,whereas existing various Ca regulation methods have been greatly restricted in their clinical applications due to their high toxicity and inefficiency.To solve this issue,with the help of Ca overexpressed tumor drug resistance model,the phytic acid(PA)-modified CeO_(2) nano-inhibitors have been rationally designed as an unprecedentedly safe and efficient Ca2+inhibitor to successfully reverse tumor drug resistance through Ca^(2+)negative regulation strategy.Using doxorubicin(Dox)as a model chemotherapeutic drug,the Ca^(2+)nano-inhibitors efficiently deprived intracellular excessive free Ca2+,suppressed P-glycoprotein(P-gp)expression and significantly enhanced intracellular drug accumulation in Dox-resistant tumor cells.This Ca^(2+)negative regulation strategy improved the intratumoral Dox concentration by a factor of 12.4 and nearly eradicated tumors without obvious adverse effects.Besides,nanocerias as pH-regulated nanozyme greatly alleviated the adverse effects of chemotherapeutic drug on normal cells/organs and substantially improved survivals of mice.We anticipate that this safe and effective Ca^(2+)negative regulation strategy has potentials to conquer the pitfalls of traditional Ca inhibitors,improve therapeutic efficacy of common chemotherapeutic drugs and serves as a facile and effective treatment platform of other Ca^(2+) associated diseases.
