71 research outputs found
ANALYSE CHIMIQUE QUANTITATIVE A HAUTE RESOLUTION SPATIALE PAR MICROSONDE ET NANOSONDE NUCLEAIRE
The study of the role of trace elements at cellular level requires the use of state-of-the-art analytical tools that could achieve enough sensitivity and spatial resolution. We developed a new methodology for the accurate quantification of chemical element distribution in single cells based on a combination of ion beam analysis techniques STIM, PIXE and RBS. The quantification procedure relies on the development of a STIM data analysis software (Paparamborde). Validity of this methodology and limits are discussed here. The method allows the quantification of trace elements (ÎŒg/g) with a 19.8 % uncertainty in cellular compartments with mass below 0.1 ng. The main limit of the method lies in the poor number of samples that can be analyzed, due to long irradiation times required and limited access to ion beam analysis facilities. This is the reason why we developed a database for cellular chemical composition capitalization (BDC4). BDC4 has been designed in order to use cellular chemical composition as a tracer for biological activities and is expected to provide in the future reference chemical compositions for any cellular type or compartment. Application of the STIM-PIXE-RBS methodology to the study of nuclear toxicology of cobalt compounds is presented here showing that STIM analysis is absolutely needed when organic mass loss appears during PIXE-RBS irradiation.Etudier le rĂŽle des Ă©lĂ©ments traces Ă lâĂ©chelle cellulaire requiert des outils analytiques de pointe. Nous avons dĂ©veloppĂ© une nouvelle mĂ©thodologie prĂ©cise de la rĂ©partition des Ă©lĂ©ments chimiques cellulaires Ă partir dâune combinaison des mĂ©thodes dâanalyse par faisceaux dâions PIXE, RBS et STIM. Cette mĂ©thodologie sâappuie fortement sur le dĂ©veloppement dâun logiciel (Paparamborde) pour le traitement quantitatif des expĂ©riences STIM. La validitĂ© de cette mĂ©thode ainsi que ses limites sont discutĂ©es. La mĂ©thode STIM-PIXE-RBS permet de quantifier la composition en Ă©lĂ©ments traces (ÎŒg/g) avec une incertitude de mesure Ă©valuĂ©e Ă 19,8% dans des compartiments cellulaires de masse infĂ©rieure Ă 0,1 ng. Une des limites de la mĂ©thode rĂ©side dans le faible nombre dâĂ©chantillons analysables en raison Ă la fois du temps minimum nĂ©cessaire pour rĂ©aliser une acquisition et de lâaccĂšs limitĂ© aux plateformes dâanalyse par faisceaux dâions. Câest pourquoi nous avons Ă©galement dĂ©veloppĂ© une base de donnĂ©es pour la capitalisation des compositions chimiques cellulaires (BDC4). Cette base de donnĂ©es sâinscrit dans la logique de lâutilisation de la composition chimique cellulaire comme un traceur de lâactivitĂ© biologique, et doit permettre Ă terme de dĂ©finir des compositions chimiques de rĂ©fĂ©rence pour les diffĂ©rents types cellulaires analysĂ©s. Lâapplication de la mĂ©thodologie STIM-PIXE-RBS Ă lâĂ©tude de la toxicologie nuclĂ©aire du cobalt permet dâillustrer son intĂ©rĂȘt en pratique. En particulier, lâanalyse STIM sâavĂšre indispensable dans le cas dâĂ©chantillons prĂ©sentant une perte de masse organique au cours de lâanalyse PIXE-RBS
Iron Storage within Dopamine Neurovesicles Revealed by Chemical Nano-Imaging
Altered homeostasis of metal ions is suspected to play a critical role in neurodegeneration. However, the lack of analytical technique with sufficient spatial resolution prevents the investigation of metals distribution in neurons. An original experimental setup was developed to perform chemical element imaging with a 90 nm spatial resolution using synchrotron-based X-ray fluorescence. This unique spatial resolution, combined to a high brightness, enables chemical element imaging in subcellular compartments. We investigated the distribution of iron in dopamine producing neurons because iron-dopamine compounds are suspected to be formed but have yet never been observed in cells. The study shows that iron accumulates into dopamine neurovesicles. In addition, the inhibition of dopamine synthesis results in a decreased vesicular storage of iron. These results indicate a new physiological role for dopamine in iron buffering within normal dopamine producing cells. This system could be at fault in Parkinson's disease which is characterized by an increased level of iron in the substancia nigra pars compacta and an impaired storage of dopamine due to the disruption of vesicular trafficking. The re-distribution of highly reactive dopamine-iron complexes outside neurovesicles would result in an enhanced death of dopaminergic neurons
Analyse chimique quantitative à haute résolution spatiale par microsonde et nanosonde nucléaires
Etudier le rĂŽle des Ă©lĂ©ments traces Ă lâĂ©chelle cellulaire requiert des outils analytiques de pointe. Nous avons dĂ©veloppĂ© une nouvelle mĂ©thodologie prĂ©cise de la rĂ©partition des Ă©lĂ©ments chimiques cellulaires Ă partir dâune combinaison des mĂ©thodes dâanalyse par faisceaux dâions PIXE, RBS et STIM. Cette mĂ©thodologie sâappuie fortement sur le dĂ©veloppement dâun logiciel (Paparamborde) pour le traitement quantitatif des expĂ©riences STIM. La validitĂ© de cette mĂ©thode ainsi que ses limites sont discutĂ©es. La mĂ©thode STIM-PIXE-RBS permet de quantifier la composition en Ă©lĂ©ments traces (”g/g) avec une incertitude de mesure Ă©valuĂ©e Ă 19,8% dans des compartiments cellulaires de masse infĂ©rieure Ă 0,1 ng.Une des limites de la mĂ©thode rĂ©side dans le faible nombre dâĂ©chantillons analysables en raison Ă la fois du temps minimum nĂ©cessaire pour rĂ©aliser une acquisition et de lâaccĂšs limitĂ© aux plateformes dâanalyse par faisceaux dâions. Câest pourquoi nous avons Ă©galement dĂ©veloppĂ© une base de donnĂ©es pour la capitalisation des compositions chimiques cellulaires (BDC4). Cette base de donnĂ©es sâinscrit dans la logique de lâutilisation de la composition chimique cellulaire comme un traceur de lâactivitĂ© biologique, et doit permettre Ă terme de dĂ©finir des compositions chimiques de rĂ©fĂ©rence pour les diffĂ©rents types cellulaires analysĂ©s.Lâapplication de la mĂ©thodologie STIM-PIXE-RBS Ă lâĂ©tude de la toxicologie nuclĂ©aire du cobalt permet dâillustrer son intĂ©rĂȘt en pratique. En particulier, lâanalyse STIM sâavĂšre indispensable dans le cas dâĂ©chantillons prĂ©sentant une perte de masse organique au cours de lâanalyse PIXE-RBS.The study of the role of trace elements at cellular level requires the use of state-of-the-art analytical tools that could achieve enough sensitivity and spatial resolution. We developed a new methodology for the accurate quantification of chemical element distribution in single cells based on a combination of ion beam analysis techniques STIM, PIXE and RBS. The quantification procedure relies on the development of a STIM data analysis software (Paparamborde). Validity of this methodology and limits are discussed here. The method allows the quantification of trace elements (”g/g) with a 19.8 % uncertainty in cellular compartments with mass below 0.1 ng.The main limit of the method lies in the poor number of samples that can be analyzed, due to long irradiation times required and limited access to ion beam analysis facilities. This is the reason why we developed a database for cellular chemical composition capitalization (BDC4). BDC4 has been designed in order to use cellular chemical composition as a tracer for biological activities and is expected to provide in the future reference chemical compositions for any cellular type or compartment.Application of the STIM-PIXE-RBS methodology to the study of nuclear toxicology of cobalt compounds is presented here showing that STIM analysis is absolutely needed when organic mass loss appears during PIXE-RBS irradiation
Quantitative analysis of chemical elements in single cells using nuclear microprobe and nanoprobe
Etudier le rĂŽle des Ă©lĂ©ments traces Ă lâĂ©chelle cellulaire requiert des outils analytiques de pointe. Nous avons dĂ©veloppĂ© une nouvelle mĂ©thodologie prĂ©cise de la rĂ©partition des Ă©lĂ©ments chimiques cellulaires Ă partir dâune combinaison des mĂ©thodes dâanalyse par faisceaux dâions PIXE, RBS et STIM. Cette mĂ©thodologie sâappuie fortement sur le dĂ©veloppement dâun logiciel (Paparamborde) pour le traitement quantitatif des expĂ©riences STIM. La validitĂ© de cette mĂ©thode ainsi que ses limites sont discutĂ©es. La mĂ©thode STIM-PIXE-RBS permet de quantifier la composition en Ă©lĂ©ments traces (ÎŒg/g) avec une incertitude de mesure Ă©valuĂ©e Ă 19,8% dans des compartiments cellulaires de masse infĂ©rieure Ă 0,1 ng. Une des limites de la mĂ©thode rĂ©side dans le faible nombre dâĂ©chantillons analysables en raison Ă la fois du temps minimum nĂ©cessaire pour rĂ©aliser une acquisition et de lâaccĂšs limitĂ© aux plateformes dâanalyse par faisceaux dâions. Câest pourquoi nous avons Ă©galement dĂ©veloppĂ© une base de donnĂ©es pour la capitalisation des compositions chimiques cellulaires (BDC4). Cette base de donnĂ©es sâinscrit dans la logique de lâutilisation de la composition chimique cellulaire comme un traceur de lâactivitĂ© biologique, et doit permettre Ă terme de dĂ©finir des compositions chimiques de rĂ©fĂ©rence pour les diffĂ©rents types cellulaires analysĂ©s. Lâapplication de la mĂ©thodologie STIM-PIXE-RBS Ă lâĂ©tude de la toxicologie nuclĂ©aire du cobalt permet dâillustrer son intĂ©rĂȘt en pratique. En particulier, lâanalyse STIM sâavĂšre indispensable dans le cas dâĂ©chantillons prĂ©sentant une perte de masse organique au cours de lâanalyse PIXE-RBS.The study of the role of trace elements at cellular level requires the use of state-of-the-art analytical tools that could achieve enough sensitivity and spatial resolution. We developed a new methodology for the accurate quantification of chemical element distribution in single cells based on a combination of ion beam analysis techniques STIM, PIXE and RBS. The quantification procedure relies on the development of a STIM data analysis software (Paparamborde). Validity of this methodology and limits are discussed here. The method allows the quantification of trace elements (ÎŒg/g) with a 19.8 % uncertainty in cellular compartments with mass below 0.1 ng. The main limit of the method lies in the poor number of samples that can be analyzed, due to long irradiation times required and limited access to ion beam analysis facilities. This is the reason why we developed a database for cellular chemical composition capitalization (BDC4). BDC4 has been designed in order to use cellular chemical composition as a tracer for biological activities and is expected to provide in the future reference chemical compositions for any cellular type or compartment. Application of the STIM-PIXE-RBS methodology to the study of nuclear toxicology of cobalt compounds is presented here showing that STIM analysis is absolutely needed when organic mass loss appears during PIXE-RBS irradiation
Analyse chimique quantitative à haute résolution spatiale par microsonde et nanosonde nucléaires
Etudier le rĂŽle des Ă©lĂ©ments traces Ă lâĂ©chelle cellulaire requiert des outils analytiques de pointe. Nous avons dĂ©veloppĂ© une nouvelle mĂ©thodologie prĂ©cise de la rĂ©partition des Ă©lĂ©ments chimiques cellulaires Ă partir dâune combinaison des mĂ©thodes dâanalyse par faisceaux dâions PIXE, RBS et STIM. Cette mĂ©thodologie sâappuie fortement sur le dĂ©veloppement dâun logiciel (Paparamborde) pour le traitement quantitatif des expĂ©riences STIM. La validitĂ© de cette mĂ©thode ainsi que ses limites sont discutĂ©es. La mĂ©thode STIM-PIXE-RBS permet de quantifier la composition en Ă©lĂ©ments traces (”g/g) avec une incertitude de mesure Ă©valuĂ©e Ă 19,8% dans des compartiments cellulaires de masse infĂ©rieure Ă 0,1 ng.Une des limites de la mĂ©thode rĂ©side dans le faible nombre dâĂ©chantillons analysables en raison Ă la fois du temps minimum nĂ©cessaire pour rĂ©aliser une acquisition et de lâaccĂšs limitĂ© aux plateformes dâanalyse par faisceaux dâions. Câest pourquoi nous avons Ă©galement dĂ©veloppĂ© une base de donnĂ©es pour la capitalisation des compositions chimiques cellulaires (BDC4). Cette base de donnĂ©es sâinscrit dans la logique de lâutilisation de la composition chimique cellulaire comme un traceur de lâactivitĂ© biologique, et doit permettre Ă terme de dĂ©finir des compositions chimiques de rĂ©fĂ©rence pour les diffĂ©rents types cellulaires analysĂ©s.Lâapplication de la mĂ©thodologie STIM-PIXE-RBS Ă lâĂ©tude de la toxicologie nuclĂ©aire du cobalt permet dâillustrer son intĂ©rĂȘt en pratique. En particulier, lâanalyse STIM sâavĂšre indispensable dans le cas dâĂ©chantillons prĂ©sentant une perte de masse organique au cours de lâanalyse PIXE-RBS.The study of the role of trace elements at cellular level requires the use of state-of-the-art analytical tools that could achieve enough sensitivity and spatial resolution. We developed a new methodology for the accurate quantification of chemical element distribution in single cells based on a combination of ion beam analysis techniques STIM, PIXE and RBS. The quantification procedure relies on the development of a STIM data analysis software (Paparamborde). Validity of this methodology and limits are discussed here. The method allows the quantification of trace elements (”g/g) with a 19.8 % uncertainty in cellular compartments with mass below 0.1 ng.The main limit of the method lies in the poor number of samples that can be analyzed, due to long irradiation times required and limited access to ion beam analysis facilities. This is the reason why we developed a database for cellular chemical composition capitalization (BDC4). BDC4 has been designed in order to use cellular chemical composition as a tracer for biological activities and is expected to provide in the future reference chemical compositions for any cellular type or compartment.Application of the STIM-PIXE-RBS methodology to the study of nuclear toxicology of cobalt compounds is presented here showing that STIM analysis is absolutely needed when organic mass loss appears during PIXE-RBS irradiation
In-air scanning transmission ion microscopy of cultured cancer cells
International audienceScanning transmission ion microscopy (STIM) imaging of living cultured cells has been carried out using a proton external-beam with the nuclear microprobe of Bordeaux-Gradignan. STIM could be performed in air atmosphere after passage of a focused proton beam through a 150 nm thick silicon nitride window. Energy loss STIM images were obtained with a spatial resolution in the micrometer range and enabled the identification of sub-cellular ultrastructures
Paparamborde: a software dedicated to quantitative mapping of biological samples using scanning transmission ion microscopy
Paparamborde, Programme d'Analyse des PArticules RAlenties dans la MatiĂšre de BORDEaux, a software dedicated to the scanning transmission ion microscopy (STIM) analysis of biological samples was developed. The programme includes the reconstruction of the median and/or mean energy loss image of the sample, as well as accurate calculation of sample thickness performed over the whole or a part of the scanned surface. The calculation is based on the conversion of transmitted particle energy into areal density of matter (g/cm) and uses SRIM code for the stopping power calculation. A new routine for the calculation of X-ray absorption correction factors (XCF), as needed for PIXE quantification of trace element, has been added in the latest version of Paparamborde, allowing the thickness heterogeneity of sample to be properly taken into account in the calculation of XCF
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