Ambient particulate matter(PM)can cause adverse health effects via their ability to produce Reactive Oxygen Species(ROS).Water-Soluble Organic Compounds(WSOCs),a complex mixture of organic compounds which usually coex...Ambient particulate matter(PM)can cause adverse health effects via their ability to produce Reactive Oxygen Species(ROS).Water-Soluble Organic Compounds(WSOCs),a complex mixture of organic compounds which usually coexist with Transition Metals(TMs)in PM,have been found to contribute to ROS formation.However,the interaction between WSOCs and TMs and its effect on ROS generation are still unknown.In this study,we examined the ROS concentrations of V,Zn,Suwannee River Fulvic Acid(SRFA),Suwannee River Humic Acid(SRHA)and the mixtures of V/Zn and SRFA/SRHA by using a cell-free 2’,7’-Dichlorodihydrofluorescein(DCFH)assay.The results showed that V or Zn synergistically promoted ROS generated by SRFA,but had an antagonistic effect on ROS generated by SRHA.Fluorescence quenching experiments indicated that V and Zn were more prone to form stable complexes with aromatic humic acid-like component(C1)and fulvic acidlike component(C3)in SRFA and SRHA.Results suggested that the underlying mechanism involving the fulvic acid-like component in SRFA more tending to complex with TMs to facilitate ROS generation throughπelectron transfer.Our work showed that the complexing ability and complexing stability of atmospheric PM organics with metals could significantly affect ROS generation.It is recommended that the research deploying multiple analytical methods to quantify the impact of PM components on public health and environment is needed in the future.展开更多
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
The great promise of photodynamic therapy(PDT) has thrusted the rapid progress of developing highly effective photosensitizers(PS) in killing cancerous cells and bacteria. To mitigate the intrinsic limitations of the ...The great promise of photodynamic therapy(PDT) has thrusted the rapid progress of developing highly effective photosensitizers(PS) in killing cancerous cells and bacteria. To mitigate the intrinsic limitations of the classical molecular photosensitizers, researchers have been looking into designing new generation of nanomaterial-based photosensitizers(nano-photosensitizers) with better photostability and higher singlet oxygen generation(SOG) efficiency, and ways of enhancing the performance of existing photosensitizers. In this paper, we review the recent development of nano-photosensitizers and nanoplasmonic strategies to enhance the SOG efficiency for better PDT performance. Firstly, we explain the mechanism of reactive oxygen species generation by classical photosensitizers, followed by a brief discussion on the commercially available photosensitizers and their limitations in PDT. We then introduce three types of new generation nanophotosensitizers that can effectively produce singlet oxygen molecules under visible light illumination, i.e., aggregation-induced emission nanodots, metal nanoclusters (< 2 nm), and carbon dots. Different design approaches to synthesize these nano-photosensitizers were also discussed. To further enhance the SOG rate of nano-photosensitizers, plasmonic strategies on using different types of metal nanoparticles in both colloidal and planar metal-PS systems are reviewed. The key parameters that determine the metal-enhanced SOG(ME-SOG) efficiency and their underlined enhancement mechanism are discussed. Lastly, we highlight the future prospects of these nanoengineering strategies, and discuss how the future development in nanobiotechnology and theoretical simulation could accelerate the design of new photosensitizers and ME-SOG systems for highly effective image-guided photodynamic therapy.展开更多
A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe lea...A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity.However,the critical role of Fe species during the electrocatalytic process is still under evaluation.Herein,we report nickel(oxy)hydroxide incorporated with Fe through the surface reconstruction of a bimetallic metal-organic framework(NiFe-MOF)during the water oxidation process.The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni^(4+),which directly correlates with an enhanced OER activity.Both the geometric and electronic structu res of the as-reconstructed Ni_(1-x)Fe_(x)OOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF,further affecting the catalytic activity.As a result,the Ni_(1-x)Fe_(x)OOH derived from Ni_(0.9)Fe_(0.1)-MOF delivers low overpotentials of 260 mV at 10 mA cm^(-2)and 400 mV at 300 mA cm^(-2).展开更多
Atmospheric humic-like substances （HULIS） are not only an unresolved mixture of macro- organic compounds but also powerful chelating agents in atmospheric particulate matters （PMs）; impacting on both the propertie...Atmospheric humic-like substances （HULIS） are not only an unresolved mixture of macro- organic compounds but also powerful chelating agents in atmospheric particulate matters （PMs）; impacting on both the properties of aerosol particles and health effects by generating reactive oxygen spedes （ROS）. Currently, the interests of HULIS are intensively shifting to the investigations of HULIS-metal synergic effects and kinetics modeling studies, as well as the development of HULIS quantification, findings of possible HULIS sources and generation of ROS from HULIS. In light of HULIS studies, we comprehensively review the current knowledge of isolation and physicochemical characterization of HULIS from atmospheric samples as well as HULIS properties （hygroscopic, surface activity, and colloidal） and possible sources of HULIS. This review mainly highlights the generation of reactive oxygen species （ROS） from PMs, HULIS and transition metals, especially iron. This review also summarized the mechanism of iron-organic complexation and recent findings of OH formation from HULIS-metal complexes. This review will be helpful to carry out the modeling studies that concern with HULIS-transition metals and for further studies in the generation of ROS from HULIS-metal complexes,展开更多
Arsenic(As)contaminated food chains have emerged as a serious public concern for humans and animals and are known to affect the cultivation of edible crops throughout the world.Therefore,the present study was designed...Arsenic(As)contaminated food chains have emerged as a serious public concern for humans and animals and are known to affect the cultivation of edible crops throughout the world.Therefore,the present study was designed to investigate the individual as well as the combined effects of exogenous silicon(Si)and sodium nitroprusside(SNP),a nitric oxide(NO)donor,on plant growth,metabolites,and antioxidant defense systems of radish(Raphanus sativus L.)plants under three different concentrations of As stress,i.e.,0.3,0.5,and 0.7 mM in a pot experiment.The results showed that As stress reduced the growth parameters of radish plants by increasing the level of oxidative stress markers,i.e.,malondialdehyde and hydrogen peroxide.However,foliar application of Si(2 mM)and pretreatment with SNP(100μM)alone as well as in combination with Si improved the plant growth parameters,i.e.,root length,fresh and dry weight of plants under As stress.Furthermore,As stress also reduced protein,and metabolites contents(flavonoids,phenolic and anthocyanin).Activities of antioxidative enzymes such as catalase(CAT),ascorbate peroxidase(APX),guaiacol peroxidase(POD),and polyphenol oxidase(PPO),as well as the content of non-enzymatic antioxidants(glutathione and ascorbic acid)decreased under As stress.In most of the parameters in radish,As III concentration showed maximum reduction,as compared to As I and II concentrations.However,the individual and combined application of Si and NO significantly alleviated the As-mediated oxidative stress in radish plants by increasing the protein,and metabolites content.Enhancement in the activities of CAT,APX,POD and PPO enzymes were recorded.Contents of glutathione and ascorbic acid were also enhanced in response to co-application of Si and NO under As stress.Results obtained were more pronounced when Si and NO were applied in combination under As stress,as compared to their individual application.In short,the current study highlights that Si and NO synergistically regulate plant growth through lowering the As-mediated oxidative stress by upregulating the metabolites content,activity of antioxidative enzymes and non-enzymatic antioxidants in radish plants.展开更多
基金supported by the Fundamental Research Funds for the Central Universities (No. E0E48927X2)the National Natural Science Foundation of China (No. 21677145)
文摘Ambient particulate matter(PM)can cause adverse health effects via their ability to produce Reactive Oxygen Species(ROS).Water-Soluble Organic Compounds(WSOCs),a complex mixture of organic compounds which usually coexist with Transition Metals(TMs)in PM,have been found to contribute to ROS formation.However,the interaction between WSOCs and TMs and its effect on ROS generation are still unknown.In this study,we examined the ROS concentrations of V,Zn,Suwannee River Fulvic Acid(SRFA),Suwannee River Humic Acid(SRHA)and the mixtures of V/Zn and SRFA/SRHA by using a cell-free 2’,7’-Dichlorodihydrofluorescein(DCFH)assay.The results showed that V or Zn synergistically promoted ROS generated by SRFA,but had an antagonistic effect on ROS generated by SRHA.Fluorescence quenching experiments indicated that V and Zn were more prone to form stable complexes with aromatic humic acid-like component(C1)and fulvic acidlike component(C3)in SRFA and SRHA.Results suggested that the underlying mechanism involving the fulvic acid-like component in SRFA more tending to complex with TMs to facilitate ROS generation throughπelectron transfer.Our work showed that the complexing ability and complexing stability of atmospheric PM organics with metals could significantly affect ROS generation.It is recommended that the research deploying multiple analytical methods to quantify the impact of PM components on public health and environment is needed in the future.
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Agency for Science,Technology,and Research(A*STAR)for providing financial support via SINGA scholarshipthe research support funding from the Newcastle University(RSA/CCEAMD5010)。
文摘The great promise of photodynamic therapy(PDT) has thrusted the rapid progress of developing highly effective photosensitizers(PS) in killing cancerous cells and bacteria. To mitigate the intrinsic limitations of the classical molecular photosensitizers, researchers have been looking into designing new generation of nanomaterial-based photosensitizers(nano-photosensitizers) with better photostability and higher singlet oxygen generation(SOG) efficiency, and ways of enhancing the performance of existing photosensitizers. In this paper, we review the recent development of nano-photosensitizers and nanoplasmonic strategies to enhance the SOG efficiency for better PDT performance. Firstly, we explain the mechanism of reactive oxygen species generation by classical photosensitizers, followed by a brief discussion on the commercially available photosensitizers and their limitations in PDT. We then introduce three types of new generation nanophotosensitizers that can effectively produce singlet oxygen molecules under visible light illumination, i.e., aggregation-induced emission nanodots, metal nanoclusters (< 2 nm), and carbon dots. Different design approaches to synthesize these nano-photosensitizers were also discussed. To further enhance the SOG rate of nano-photosensitizers, plasmonic strategies on using different types of metal nanoparticles in both colloidal and planar metal-PS systems are reviewed. The key parameters that determine the metal-enhanced SOG(ME-SOG) efficiency and their underlined enhancement mechanism are discussed. Lastly, we highlight the future prospects of these nanoengineering strategies, and discuss how the future development in nanobiotechnology and theoretical simulation could accelerate the design of new photosensitizers and ME-SOG systems for highly effective image-guided photodynamic therapy.
基金supported by the National Natural Science Foundation of China(22105060)the Natural Science Foundation of Hebei Province(E2020205004)+1 种基金Funding from the Science Foundation of Hebei Normal University(L2020B13)the Science and Technology Project of Hebei Education Department(BJ2021028)。
文摘A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity.However,the critical role of Fe species during the electrocatalytic process is still under evaluation.Herein,we report nickel(oxy)hydroxide incorporated with Fe through the surface reconstruction of a bimetallic metal-organic framework(NiFe-MOF)during the water oxidation process.The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni^(4+),which directly correlates with an enhanced OER activity.Both the geometric and electronic structu res of the as-reconstructed Ni_(1-x)Fe_(x)OOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF,further affecting the catalytic activity.As a result,the Ni_(1-x)Fe_(x)OOH derived from Ni_(0.9)Fe_(0.1)-MOF delivers low overpotentials of 260 mV at 10 mA cm^(-2)and 400 mV at 300 mA cm^(-2).
基金the Natural Science Foundation of China under NSFC Grant No. 21477073, 41273127 for support to conduct this research
文摘Atmospheric humic-like substances （HULIS） are not only an unresolved mixture of macro- organic compounds but also powerful chelating agents in atmospheric particulate matters （PMs）; impacting on both the properties of aerosol particles and health effects by generating reactive oxygen spedes （ROS）. Currently, the interests of HULIS are intensively shifting to the investigations of HULIS-metal synergic effects and kinetics modeling studies, as well as the development of HULIS quantification, findings of possible HULIS sources and generation of ROS from HULIS. In light of HULIS studies, we comprehensively review the current knowledge of isolation and physicochemical characterization of HULIS from atmospheric samples as well as HULIS properties （hygroscopic, surface activity, and colloidal） and possible sources of HULIS. This review mainly highlights the generation of reactive oxygen species （ROS） from PMs, HULIS and transition metals, especially iron. This review also summarized the mechanism of iron-organic complexation and recent findings of OH formation from HULIS-metal complexes. This review will be helpful to carry out the modeling studies that concern with HULIS-transition metals and for further studies in the generation of ROS from HULIS-metal complexes,
文摘Arsenic(As)contaminated food chains have emerged as a serious public concern for humans and animals and are known to affect the cultivation of edible crops throughout the world.Therefore,the present study was designed to investigate the individual as well as the combined effects of exogenous silicon(Si)and sodium nitroprusside(SNP),a nitric oxide(NO)donor,on plant growth,metabolites,and antioxidant defense systems of radish(Raphanus sativus L.)plants under three different concentrations of As stress,i.e.,0.3,0.5,and 0.7 mM in a pot experiment.The results showed that As stress reduced the growth parameters of radish plants by increasing the level of oxidative stress markers,i.e.,malondialdehyde and hydrogen peroxide.However,foliar application of Si(2 mM)and pretreatment with SNP(100μM)alone as well as in combination with Si improved the plant growth parameters,i.e.,root length,fresh and dry weight of plants under As stress.Furthermore,As stress also reduced protein,and metabolites contents(flavonoids,phenolic and anthocyanin).Activities of antioxidative enzymes such as catalase(CAT),ascorbate peroxidase(APX),guaiacol peroxidase(POD),and polyphenol oxidase(PPO),as well as the content of non-enzymatic antioxidants(glutathione and ascorbic acid)decreased under As stress.In most of the parameters in radish,As III concentration showed maximum reduction,as compared to As I and II concentrations.However,the individual and combined application of Si and NO significantly alleviated the As-mediated oxidative stress in radish plants by increasing the protein,and metabolites content.Enhancement in the activities of CAT,APX,POD and PPO enzymes were recorded.Contents of glutathione and ascorbic acid were also enhanced in response to co-application of Si and NO under As stress.Results obtained were more pronounced when Si and NO were applied in combination under As stress,as compared to their individual application.In short,the current study highlights that Si and NO synergistically regulate plant growth through lowering the As-mediated oxidative stress by upregulating the metabolites content,activity of antioxidative enzymes and non-enzymatic antioxidants in radish plants.
