Cadmium(Cd)is a toxic trace metal that occurs naturally in agricultural soils and can accumulate in the edible parts of crops,notably in cereal grains.This study investigated the extent to which sulfur(S)fertilization...Cadmium(Cd)is a toxic trace metal that occurs naturally in agricultural soils and can accumulate in the edible parts of crops,notably in cereal grains.This study investigated the extent to which sulfur(S)fertilization increases the availability of Cd in a calcareous(Calc)and a non-calcareous(Ncalc)soil.Changes in Cd availability and speciation were monitored over a 21-d incubation period,along with changes in pH and the concentrations of sulfate,nitrate,calcium,magnesium,aluminum(Al),manganese(Mn),and nickel(Ni)in the potassium nitrate(KNO_(3))extracts,after the addition at agronomic rates of three forms of S fertilizers:elemental S(S(0)),potassium sulfate(K_(2)SO_(4)),and ammonium sulfate((NH_(4))_(2)SO_(4)).Elemental S did not increase the Cd concentration in the KNO_(3)extracts of either soil due to its too limited oxidation to sulfates.The two sulfate fertilizers had contrasting effects on Cd concentration depending on the nature of the counter cation(K^(+)or NH_(4)^(+)).While K_(2)SO_(4)caused almost no change in Cd concentration in either soil,(NH_(4))_(2)SO_(4)increased Cd concentration in both soils.The nitrification of NH_(4)^(+)reduced soil pH,thereby increasing the concentrations of Cd,Al,Mn,and Ni in the Ncalc soil over time,as evidenced by the strong negative correlations between soil pH and the concentrations of these four elements in the KNO3 extract after 21 d.In the Calc soil,the mechanism of Cd concentration increase after(NH_(4))_(2)SO_(4)addition was more difficult to understand and could result from the proton-mediated alteration of Cd-bearing phases such as carbonates,following ammonia(NH_(3))volatilization.The relevance of these results for the S fertilization of cereals in Cd-contaminated soils is discussed.展开更多
New“all-in-one”theranostic systems,combining a magnetic resonance imaging(MRI)contrast agent with a biphotonic photodynamic therapy(2P-PDT)photosensitiser generating cytotoxic singlet oxygen,were envisaged and synth...New“all-in-one”theranostic systems,combining a magnetic resonance imaging(MRI)contrast agent with a biphotonic photodynamic therapy(2P-PDT)photosensitiser generating cytotoxic singlet oxygen,were envisaged and synthesised.They are based on azamacrocycles,regiospecifically functionalised by two-photon PDTπ-conjugated dibromobenzene-picolinate photosensitisers and acetate,able to complex gadolinium(III)and allow an MRI signal.Our approach was to use two different macrocyclic platforms,tacn and pyclen,for modulating simultaneously the structures,properties and solubility of the complexes.Photophysical properties of the ligands and their gadolinium(III)complexes were fully investigated.The Gd^(3+)-pyclen derivative showed the best water solubility and the greatest value of singlet oxygen generation of the series withΦ_(Δ)=0.53 enabling in vitro studies.The biological PDT activity under mono and biphotonic excitation was evaluated in human breast cancer cells(MCF-7).While a very low dark toxicity was observed,an almost total cell death was induced after only 3 successive irradiations of 1.57 s.Finally,its relaxivity was measured in a DMSO/H_(2)O solvent mixture with r_(1p)=11.21 and r_(2p)=24.60 mM^(-1)s^(-1)at 3.0 T and T_(1)-and T_(2)-weighted phantom MR images were obtained highlighting a first generation of“all-in-one”PDT/MRI theranostic agents.展开更多
基金supported by the CNRS-INSU EC2CO program in the framework of the CADSOU project,by the Nouvelle Aquitaine Region in the framework of the ESTOCADE project,and by the French National Research Institute for Agriculture,Food and Environment(INRAE)The authors are grateful to Ms.Melike Emet(INRAE,UMR ISPA)and Ms.Sylvie Bussière(INRAE,UMR ISPA)for their help treating the samples,and to Ms.Francesca Degan(ARVALIS-Institut du végétal)and Ms.Séverine Piutti(INRAE,UMR LAE)for helpful comments.
文摘Cadmium(Cd)is a toxic trace metal that occurs naturally in agricultural soils and can accumulate in the edible parts of crops,notably in cereal grains.This study investigated the extent to which sulfur(S)fertilization increases the availability of Cd in a calcareous(Calc)and a non-calcareous(Ncalc)soil.Changes in Cd availability and speciation were monitored over a 21-d incubation period,along with changes in pH and the concentrations of sulfate,nitrate,calcium,magnesium,aluminum(Al),manganese(Mn),and nickel(Ni)in the potassium nitrate(KNO_(3))extracts,after the addition at agronomic rates of three forms of S fertilizers:elemental S(S(0)),potassium sulfate(K_(2)SO_(4)),and ammonium sulfate((NH_(4))_(2)SO_(4)).Elemental S did not increase the Cd concentration in the KNO_(3)extracts of either soil due to its too limited oxidation to sulfates.The two sulfate fertilizers had contrasting effects on Cd concentration depending on the nature of the counter cation(K^(+)or NH_(4)^(+)).While K_(2)SO_(4)caused almost no change in Cd concentration in either soil,(NH_(4))_(2)SO_(4)increased Cd concentration in both soils.The nitrification of NH_(4)^(+)reduced soil pH,thereby increasing the concentrations of Cd,Al,Mn,and Ni in the Ncalc soil over time,as evidenced by the strong negative correlations between soil pH and the concentrations of these four elements in the KNO3 extract after 21 d.In the Calc soil,the mechanism of Cd concentration increase after(NH_(4))_(2)SO_(4)addition was more difficult to understand and could result from the proton-mediated alteration of Cd-bearing phases such as carbonates,following ammonia(NH_(3))volatilization.The relevance of these results for the S fertilization of cereals in Cd-contaminated soils is discussed.
基金ANR(SADAM ANR-16-CE07-0015-02)Hungarian National Research,Development and Innovation Office(NKFIH K-128201 and 134694 projects)+1 种基金EU and co-financed by the European Regional Development Fund under the project GINOP-2.3.2-15-2016-00008French National Research Agency(ANR-10-INBS-04,«Investments for the future»)。
文摘New“all-in-one”theranostic systems,combining a magnetic resonance imaging(MRI)contrast agent with a biphotonic photodynamic therapy(2P-PDT)photosensitiser generating cytotoxic singlet oxygen,were envisaged and synthesised.They are based on azamacrocycles,regiospecifically functionalised by two-photon PDTπ-conjugated dibromobenzene-picolinate photosensitisers and acetate,able to complex gadolinium(III)and allow an MRI signal.Our approach was to use two different macrocyclic platforms,tacn and pyclen,for modulating simultaneously the structures,properties and solubility of the complexes.Photophysical properties of the ligands and their gadolinium(III)complexes were fully investigated.The Gd^(3+)-pyclen derivative showed the best water solubility and the greatest value of singlet oxygen generation of the series withΦ_(Δ)=0.53 enabling in vitro studies.The biological PDT activity under mono and biphotonic excitation was evaluated in human breast cancer cells(MCF-7).While a very low dark toxicity was observed,an almost total cell death was induced after only 3 successive irradiations of 1.57 s.Finally,its relaxivity was measured in a DMSO/H_(2)O solvent mixture with r_(1p)=11.21 and r_(2p)=24.60 mM^(-1)s^(-1)at 3.0 T and T_(1)-and T_(2)-weighted phantom MR images were obtained highlighting a first generation of“all-in-one”PDT/MRI theranostic agents.
