Cette recherche a été financée par l&#39;Initiative de Santé Canada de recherche en génomique et le développement (GRDI) et la Stratégie canadienne de réglementation de la biotechnologie (SCRB). Les auteurs ne sont pas de conflit d&#39;intérêts.

<ol>
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Rev. 27 (2), 120-139 (2009).</li><li>Cadet, J., Bellon, S., Douki, T., Frelon, S., Gasparutto, D., Muller, E., Pouget, J. P., Ravanat, J. L., Romieu, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Radiation-induced+DNA+damage:+formation,+measurement,+and+biochemical+features.">Radiation-induced DNA damage: formation, measurement, and biochemical features.</a> J Environ Pathol Toxicol Oncol. 23 (1), 23-23 (2004).</li><li>Weiss, J. M., Goode, E. L., Ladiges, W. C., Ulrich, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymorphic+variation+in+hOGG1+and+risk+of+cancer:+a+review+of+the+functional+and+epidemiologic+literature.">Polymorphic variation in hOGG1 and risk of cancer: a review of the functional and epidemiologic literature.</a> Mol. Carcinog. 42 (3), 127-141 (2005).</li><li>Culp, S. 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T., Sowers, L. C., Hwang, S., Chung, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=First+principles+calculations+of+the+tautomers+and+pKa+values+of+8-oxoguanine:+implications+for+mutagenicity+and+repair.">First principles calculations of the tautomers and pKa values of 8-oxoguanine: implications for mutagenicity and repair.</a> Chem. Res. Toxicol. 15 (8), 1023-1035 (2002).</li><li>Park, J. -. H., Gopishetty, S., Szewczuk, L. M., Troxel, A. B., Harvey, R. G., Penning, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+8-oxo-7,8-dihydro-2'-deoxyguanosine+(8-oxo-dGuo)+by+PAH+o-quinones:+involvement+of+reactive+oxygen+species+and+copper(ii)/copper(i)+redox+cycling.">Formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo) by PAH o-quinones: involvement of reactive oxygen species and copper(ii)/copper(i) redox cycling.</a> Chem. Res. Toxicol. 18 (6), 1026-1037 (2005).</li><li>Mangal, D., Vudathala, D., Park, J. H., Lee, S. H., Penning, T. M., Blair, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+7,8-dihydro-8-oxo-2'-deoxyguanosine+in+cellular+DNA+during+oxidative+stress.">Analysis of 7,8-dihydro-8-oxo-2'-deoxyguanosine in cellular DNA during oxidative stress.</a> Chem. Res. Toxicol. 22 (5), 788-797 (2009).</li><li>Ravanat, J. L., Douki, T., Duez, P., Gremaud, E., Herbert, K., Hofer, T., Lasserre, L., Saint-Pierre, C., Favier, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+background+level+of+8-oxo-7,8-dihydro-2'-deoxyguanosine:+an+isotope+based+method+to+evaluate+artefactual+oxidation+of+DNA+during+its+extraction+and+subsequent+work-up.">Cellular background level of 8-oxo-7,8-dihydro-2'-deoxyguanosine: an isotope based method to evaluate artefactual oxidation of DNA during its extraction and subsequent work-up.</a> Carcinogenesis. 23 (11), 1911-1918 (2002).</li><li>Gossen, J. A., De Leeuw, W. J. F., Tan, C. H. T., Zwarthoff, E. C., Berends, F., Lohman, P. H. M., Knook, D. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+an+HPLC+method+with+electrochemical+detection+of+femtomoles+of+8-oxo-7,8-dihydroguanine+and+8-oxo-7,8-dihydro-2'-deoxyguanosine+in+the+presence+of+uric+acid.">Development of an HPLC method with electrochemical detection of femtomoles of 8-oxo-7,8-dihydroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine in the presence of uric acid.</a> Talanta. 63 (2), 323-331 (2004).</li><li>Ravanat, J. -. L., Turesky, R. J., Gremaud, E., Trudel, L. J., Stadler, R. 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Toxicol. 8 (8), 1039-1045 (1995).</li><li>Kawanishi, S., Murata, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+of+DNA+damage+induced+by+bromate+differs+from+general+types+of+oxidative+stress.">Mechanism of DNA damage induced by bromate differs from general types of oxidative stress.</a> Toxicology. 221 (2-3), 172-178 (2006).</li><li>Tahara, S., Kaneko, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Susceptibility+of+mouse+splenic+cells+to+oxidative+DNA+damage+by+x-ray+irradiation.">Susceptibility of mouse splenic cells to oxidative DNA damage by x-ray irradiation.</a> Biol. Pharm. Bull. 27 (1), 105-108 (2004).</li><li>Garratt, L. W., Mistry, V., Singh, R., Sandhu, J. K., Sheil, B., Cooke, M. S., Sly, P. 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No conflict of interest or competing financial interests declared.

Bien que 8-oxo-dGuo a été rapporté comme un biomarqueur utile de l&#39;oxydation de l&#39;ADN, sa quantification fiable peut représenter un défi. Bien que plusieurs méthodes publiées existent, il ya une nécessité d&#39;une approche globale, aperçu descriptif du protocole pour permettre aux chercheurs de déployer la méthode dans leurs laboratoires. Ici, nous présentons un aperçu détaillé d&#39;un protocole fondé HPLC-qui ​​permettra aux nouveaux utilisateurs d&#39;établir une méthode efficace pour ...

Espèces réactives de l&#39;oxygène (ROS), dont les niveaux de l&#39;état d&#39;équilibre peut augmenter pendant de nombreuses conditions pathologiques et le métabolisme xenotoxic, contribuent à une augmentation de la fréquence des dommages oxydatifs à l&#39;ADN. Parmi plusieurs produits d&#39;oxydation possibles de nucléobases, des dommages oxydatifs de l&#39;ADN peut être facilement mesurée en utilisant le marqueur stable 8-oxo-7,8-dihydro-2&#39;-désoxyguanosine (8-oxo-dGuo), qui est l&#39;une des formes oxydées de 2 &#39; -deoxyguanosine (dGuo) 1. 8-oxo-dGuo ADN est le plus abondant lésion 2 et, par conséquent, a été étudiée de façon plus détaillée en tant que biomarqueur de l&#39;oxydation de l&#39;ADN malgré l&#39;existence de produits d&#39;oxydation de l&#39;ADN multiple 3. Chez l&#39;homme, ces dommages peuvent être réparé via la base réparation par excision de 8-oxoguanine glycosylase 1 (hOGG1) 4. Si laissé non réparés, 8-oxo-dGuo peut contribuer à la formation de base de mutations paire de substitution (ie, G à T transversions) 4. Fait important, la 8-oxo-dGuo est un marqueur établi for dommages à l&#39;ADN par rapport à l&#39;initiation et à la promotion de la cancérogenèse 2. Par conséquent, la quantification précise de la 8-oxo-dGuo est un biomarqueur utile et souhaitable de dommages oxydatifs de l&#39;ADN 5. Il ya une grande confusion dans la littérature concernant les noms corrects pour les formes oxydante endommagées de 2-désoxyguanosine et, d&#39;ailleurs, le nom correct du composé (s) régulièrement mesurés en tant que biomarqueur de lésions oxydatives de l&#39;ADN 6. Les 8-céto-6,8-dicéto-énol et 6, les formes tautomères des 8-oxo-dGuo (représenté sur la figure 1) sont les deux plus importants tautomères décrits dans la littérature 5,7. La forme 6,8-dicéto est la forme la plus importante au pH physiologique de 7,4, et est le produit d&#39;oxydation de l&#39;ADN le plus important 7. Par conséquent, 8-oxo-dGuo, plutôt que 8-hydroxy-dGuo est le nom le plus approprié pour ce produit d&#39;oxydation 6. Il est également important de noter que le 2-désoxyguanosine (dGuo), plutôt que nucleobase guanine (GUA) ribonucléoside ou guanosine (Guo), respectivement, sont détectés par la plupart des méthodes 6. Détection précise et la quantification de 8-oxo-dGuo est difficile en raison de: i) la variabilité dans la digestion de l&#39;échantillon d&#39;ADN, ii) l&#39;oxydation accidentelle de dGuo à 8-oxo-dGuo qui peut se produire lors de la préparation de l&#39;échantillon, et iii) la nécessité pour la validation effective de la méthode HPLC-ED analytique 8. Dans ce protocole, nous avons cherché à obtenir i) en fournissant des conditions, favorables à la digestion complète de l&#39;ADN et ii) par le chélateur inclusion de métal et des solutions de chélateur-traitée et un réactif d&#39;ADN isolation spéciale, tandis que iii) n&#39;a été que partiellement abordées par l&#39;inclusion de Des témoins positifs et fournissent ainsi que la méthode est capable de détecter des 8-oxo-dGuo dans des échantillons biologiques. En outre la validation est au-delà de la portée de ce document. Cependant, nous sommes convaincus que ce protocole aidera la prospectiveles utilisateurs à déterminer la mesure dans laquelle ils ont besoin de valider formellement le protocole, en fonction de leurs besoins. Une liste des étapes nécessaires à la validation formelle de la méthode est fournie plus loin. Pendant le développement et le déploiement d&#39;une méthode de détection 8-oxo-dGuo, méthodes publiées ont été revues et consolidées. Ainsi, cette méthode élimine le besoin de recueillir des informations de plusieurs sources publiées qui manquent souvent d&#39;importants détails expérimentaux tout en fournissant également des moyens rapides et simples de tester si la méthode pour la détection et la quantification de 8-oxo-dGuo a été adoptée avec succès. Ce procédé a été adapté avec succès utilisé pour analyser des échantillons d&#39;ADN à partir de cellules en culture et le tissu murin. Cet article vidéo aidera les autres groupes à établir une méthode efficace pour la détection et la quantification fiable de 8-oxo-dGuo par HPLC-ED.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>8-oxo-dGuo standard</td>
			<td>Cayman Chemical Company</td>
			<td>89320</td>
			<td>Inappropriately referred to as &#34;8-hydroxy-2&#39;-deoxy Guanosine&#34; - see Fig. 1 and text for details</td>
		</tr>
		<tr>
			<td>Alkaline phosphatase&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>P5931</td>
			<td>From E.coli</td>
		</tr>
		<tr>
			<td>Chelex 100</td>
			<td>Sigma-Aldrich</td>
			<td>C7901</td>
			<td>Chelates heavy metals</td>
		</tr>
		<tr>
			<td>Desferoxamine mesylate</td>
			<td>Sigma-Aldrich</td>
			<td>D9533</td>
			<td></td>
		</tr>
		<tr>
			<td>dGuo standard</td>
			<td>Sigma-Aldrich</td>
			<td>D7145</td>
			<td></td>
		</tr>
		<tr>
			<td>Dibasic sodium phosphate</td>
			<td>Sigma-Aldrich</td>
			<td>S9390</td>
			<td></td>
		</tr>
		<tr>
			<td>DNA from salmon sperm</td>
			<td>Sigma-Aldrich</td>
			<td>D1626</td>
			<td>Sodium salt</td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>Sigma-Aldrich</td>
			<td>D4527</td>
			<td>TypeII, from bovine pancreas</td>
		</tr>
		<tr>
			<td>DNAzol</td>
			<td>Invitrogen</td>
			<td>10503-27</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA)</td>
			<td>Sigma-Aldrich</td>
			<td>E4884</td>
			<td>The compound would not completely dissolve until solution pH is adjusted to 8.0 with e.g. NaOH</td>
		</tr>
		<tr>
			<td>F12-K media</td>
			<td>ATCC</td>
			<td>30-2004</td>
			<td></td>
		</tr>
		<tr>
			<td>Foetal bovine serum</td>
			<td>ATCC</td>
			<td>30-2020</td>
			<td></td>
		</tr>
		<tr>
			<td>Guard column</td>
			<td>Chromatographic Specialties</td>
			<td>YBA 99S03 0204GC</td>
			<td>Protects colum from contamination; may also lead to pressure build-up</td>
		</tr>
		<tr>
			<td>Magnesium chloride</td>
			<td>Sigma-Aldrich</td>
			<td>M8266</td>
			<td></td>
		</tr>
		<tr>
			<td>Monobasic sodium phosphate</td>
			<td>Sigma-Aldrich</td>
			<td>S9638</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Invitrogen</td>
			<td>15140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline</td>
			<td>Invitrogen</td>
			<td>15190-250</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphodiesterase I enzyme&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>P3243</td>
			<td>Type II from Crotalus adamaneus venom</td>
		</tr>
		<tr>
			<td>Teflon homogenizer</td>
			<td>Thomas Scientific</td>
			<td>7724T-1 or 7724T-5 for 1 or 5 mL, respectively</td>
			<td>Volume (holding capacity) depends on the amount of sample to be processed.</td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Invitrogen</td>
			<td>15050-065</td>
			<td></td>
		</tr>
		<tr>
			<td>YMC-BASIC column with bonded spherical silica</td>
			<td>Chromatographic Specialties</td>
			<td>YBA 99S03 1546WT</td>
			<td></td>
		</tr>
	</tbody>
</table>

hplc measurement of the dna oxidation biomarker, 8-oxo-7,8-dihydro-2&#8217;-deoxyguanosine, in cultured cells and animal tissues

Le stress oxydatif est associé à de nombreux processus physiologiques et pathologiques, ainsi que le métabolisme des xénobiotiques, conduisant à l&#39;oxydation des macromolécules biologiques, y compris l&#39;ADN. Par conséquent, la détection efficace de l&#39;oxydation de l&#39;ADN est important pour une variété de disciplines de recherche, y compris la médecine et de la toxicologie. Un biomarqueur commun par oxydation de l&#39;ADN endommagé est le 8-oxo-7,8-dihydro-2&#39;-désoxyguanosine (8-oxo-dGuo; souvent appelée à tort comme 8-hydroxy-2&#39;-désoxyguanosine (8-OH-dGuo ou 8 oxo-dG)). Plusieurs protocoles de mesure 8-oxo-dGuo par chromatographie liquide à haute pression avec détection électrochimique (HPLC-ED) ont été décrites. Toutefois, ceux-ci ont été principalement appliquées à l&#39;ADN purifié traité avec pro-oxydants. En outre, en raison de différences méthodologiques entre les laboratoires, principalement en raison de différences dans l&#39;équipement analytique, l&#39;adoption de méthodes publiées pour la détection de la 8-oxo-dGuo par HPLC-ED nécessite une optimisation soignée par chaque laboratoire. UNprotocole complet, décrivant un tel processus d&#39;optimisation, est absente. Ici, un protocole détaillé est décrit pour la détection de 8-oxo-dGuo par HPLC-DE, en ADN à partir de cellules en culture ou des tissus animaux. Elle illustre comment la préparation d&#39;échantillons d&#39;ADN peut être facilement et rapidement optimisée pour minimiser l&#39;oxydation indésirable de l&#39;ADN qui peut se produire au cours de la préparation des échantillons. Ce protocole montre comment détecter 8-oxo-dGuo dans des cellules humaines en culture d&#39;adénocarcinome alvéolaire (par exemple, des cellules A549) traités avec l&#39;agent oxydant KBrO 3, et à partir de la rate des souris exposées à la dibenzo d&#39;hydrocarbure aromatique polycyclique (DEF, p) chrysène (DBC, anciennement connu sous le dibenzo (a, l) pyrène, Dalp). Dans l&#39;ensemble, ce travail illustre comment une méthode HPLC-ED peut être facilement optimisée pour la détection de la 8-oxo-dGuo dans des échantillons biologiques.

dGuo a été observé à un temps de rétention de 4,7 min alors que les 8-oxo-dGuo avait un temps de rétention d&#39;environ 6,4 min (Figure 2A et B). Il n&#39;y a de différence sur 1000 fois dans les hauteurs de pics entre les deux analytes, comme on le voit sur ​​la figure 2C. Voltammogrammes pour 8-oxo-dGuo et dGuo ont été obtenus par les normes en cours d&#39;exécution à un potentiel de travail dans la gamme de 0,2 à 1,1 V. Le potentiel de travail optima...

Watch this Scientific Journal Video about HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2â€™-deoxyguanosine, in Cultured Cells and Animal Tissues at JoVE.com

HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2&amp;#8217;-deoxyguanosine, in Cultured Cells and Animal Tissues

Le but de ce protocole est la détection du marqueur de l&#39;oxydation de l&#39;ADN, 8-oxo-7,8-dihydro-2&#39;-désoxyguanosine (8-oxo-dGuo) par CLHP-DE, en ADN à partir de cellules en culture ou des tissus animaux.

HPLC: Mesure de l&#39;oxydation des biomarqueurs ADN, 8-oxo-7,8-dihydro-2&#39;-désoxyguanosine, dans des cellules cultivées et des tissus animaux

Oxidative stress is associated with many physiological and pathological processes, as well as xenobiotic metabolism, leading to the oxidation of ...

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Research

JoVE Journal

Chemistry

HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2&#8217;-deoxyguanosine, in Cultured Cells and Animal Tissues

26.2K vues.  Health Canada.  Le but de ce protocole est la détection du marqueur de l'oxydation de l'ADN, 8-oxo-7,8-dihydro-2'-désoxyguanosine (8-oxo-dGuo) par CLHP-DE, en ADN à partir de cellules en culture ou des tissus animaux. 

Vidéo: HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2&#8217;-deoxyguanosine, in Cultured Cells and Animal Tissues

Steady-state, Pre-steady-state, and Single-turnover Kinetic Measurement for DNA Glycosylase Activity

Human 8-oxoguanine DNA glycosylase (OGG1) excises the mutagenic oxidative DNA lesion 8-oxo-7,8-dihydroguanine (8-oxoG) from DNA. Kinetic characterization of OGG1 is undertaken to measure the rates of 8-oxoG excision and product release. When the OGG1 concentration is lower than substrate DNA, time courses of product formation are biphasic; a rapid exponential phase (i.e. burst) of product formation is followed by a linear steady-state phase. The initial burst of product formation corresponds to the concentration of enzyme properly engaged on the substrate, and the burst amplitude depends on the concentration of enzyme. The first-order rate constant of the burst corresponds to the intrinsic rate of 8-oxoG excision and the slower steady-state rate measures the rate of product release (product DNA dissociation rate constant, koff). Here, we describe steady-state, pre-steady-state, and single-turnover approaches to isolate and measure specific steps during OGG1 catalytic cycling. A fluorescent labeled lesion-containing oligonucleotide and purified OGG1 are used to facilitate precise kinetic measurements. Since low enzyme concentrations are used to make steady-state measurements, manual mixing of reagents and quenching of the reaction can be performed to ascertain the steady-state rate (koff). Additionally, extrapolation of the steady-state rate to a point on the ordinate at zero time indicates that a burst of product formation occurred during the first turnover (i.e. y-intercept is positive). The first-order rate constant of the exponential burst phase can be measured using a rapid mixing and quenching technique that examines the amount of product formed at short time intervals (&lt;1 sec) before the steady-state phase and corresponds to the rate of 8-oxoG excision (i.e. chemistry). The chemical step can also be measured using a single-turnover approach where catalytic cycling is prevented by saturating substrate DNA with enzyme (E&gt;S). These approaches can measure elementary rate constants that influence the efficiency of removal of a DNA lesion.

Time courses for the glycosylase activity of 8-oxoguanine DNA glycosylase are biphasic exhibiting a burst of product formation and a linear steady-state phase. Utilizing quench-flow techniques, the burst and the steady-state rates can be measured, which correspond to excision of 8-oxoguanine and release of the glycosylase from the product DNA, respectively.

L&#39;état d&#39;équilibre des mesures cinétiques, pré-état stationnaire, et un seul chiffre d&#39;affaires de l&#39;activité de ADNglycosylase

Human 8-oxoguanine DNA glycosylase (OGG1) excises the mutagenic oxidative DNA lesion 8-oxo-7,8-dihydroguanine (8-oxoG) from DNA. Kinetic characterization ...

Recherche

Chimie

HPLC-based Assay to Monitor Extracellular Nucleotide/Nucleoside Metabolism in Human Chronic Lymphocytic Leukemia Cells

This method describes a sensitive, specific, reliable and reproducible reverse phase high-performance liquid chromatography (RP-HPLC) assay developed and validated for the quantification of extracellular purine nucleotides and nucleosides produced by purified chronic lymphocytic leukemia (CLL) cells under different culture conditions. The chromatographic separation of adenosine 5&#39;-monophosphate (AMP), adenosine (ADO) and inosine (INO) is performed at RT on a silica-based, reversed-phase column that is used for polar compound retention. The method includes a binary mobile phase, which consists of 7 mM ammonium acetate and acetonitrile with a flow rate of 1.00 ml/min. The eluates are monitored using a Photodiode Array UV detector set at 260 nm. A standard calibration curve is generated to calculate the equation for the analytical quantification of each purine compound. System control, data acquisition and analysis are then performed. Applying this protocol, AMP, INO and ADO elute at 7, 11 and 11.9 min, respectively, and the total run time for each sample is 20 min. This protocol may be applied to different cell types and cell lines (both suspension and adherent), using culture media as matrix. The advantages are easy and fast sample preparation and the requirement of a small amount of supernatant for analysis. Furthermore, the use of a serum-free medium allows skipping the protein precipitation step with acetonitrile that impacts the final concentration of purine compounds. One of the limitations of the method is the requirement of the equilibration column run before each single sample run, making the total run time of the experiment longer and preventing high throughput screening applications.

The protocol described here represents an easy and reproducible method that employs reverse phase high-performance liquid chromatography (RP-HPLC) to measure purine metabolism on chronic lymphocytic leukemia (CLL) cells cultured under different conditions.

base HPLC-Assay pour surveiller extracellulaires Nucleotide / nucléosidiques Métabolisme dans les chroniques cellules leucémie lymphocytaire humaines

This method describes a sensitive, specific, reliable and reproducible reverse phase high-performance liquid chromatography (RP-HPLC) assay developed and ...

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile organic carbons (VOCs), illustrating this with a titanium dioxide based catalyst, and the VOC 2-propanol. The protocol takes advantage of field asymmetric ion mobility spectroscopy (FAIMS), an analysis tool that is capable of continuously identifying and monitoring the concentration of VOCs such as 2-propanol and acetone at the ppb level. The continuous nature of FAIMS allows detailed kinetic analysis, and long-term reactions, offering a significant advantage over gas chromatography, a batch process traditionally used in air purification characterization. The use of FAIMS in photocatalytic air purification has only recently been used for the first time, and with the protocol illustrated here, the flexibility in allowing alternative VOCs and photocatalysts to be tested using comparable protocols offers a unique system to elucidate photocatalytic air purification reactions at low concentrations.

A protocol for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) model volatile organic carbons such as 2-propanol is described.

Analysant la photo-oxydation de 2-propanol à des Concentrations de niveau Air intérieur à l’aide de la spectrométrie de mobilité ionique asymétrique champ

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile ...

Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, the focus is on metallic substrates immersed in acidic solutions containing organic corrosion inhibitors, as these systems can be particularly sensitive to oxidation following removal from solution. To minimize the likelihood of such degradation, samples are removed from solution within a glove box purged with inert gas, either N2 or Ar. The glove box is directly attached to the load-lock of the ultra-high vacuum X-ray photoelectron spectroscopy instrument, avoiding any exposure to the ambient laboratory atmosphere, and thus reducing the possibility of post immersion substrate oxidation. On this basis, one can be more certain that the X-ray photoelectron spectroscopy features observed are likely to be representative of the in situ submerged scenario, e.g. the oxidation state of the metal is not modified.

A protocol to avoid the oxidation of metallic substrates during sample transfer from an inhibited acidic solution to an X-ray photoelectron spectrometer is presented.

Détermination de la composition chimique de corrosion Inhibiteur Interfaces / métal avec XPS: Minimiser Poster Immersion Oxydation

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

Fabrication et essai de thermomètres photoniques

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS

The search for new histone deacetylase (HDAC) inhibitors is of increasing interest in drug discovery. Isoform selectivity has been in the spotlight since the approval of romidepsin, a class I HDAC inhibitor for cancer therapy, and the clinical investigation of HDAC6-specific inhibitors for multiple myeloma. The present method is used to determine the inhibitory activity of test compounds on HDAC1 and HDAC6 in cells. The isoform activity is measured using the ultra-high-performance liquid chromatography &#8211; mass spectrometry (UHPLC-MS) analysis of specific substrates incubated with treated and untreated HeLa cells. The method has the advantage of reflecting the endogenous HDAC activity within the cell environment, in contrast to cell-free biochemical assays conducted on isolated isoforms. Moreover, because it is based on the quantification of synthetic substrates, the method does not require the antibody recognition of endogenous acetylated proteins. It is easily adaptable to several cell lines and an automated process. The method has already proved useful in finding HDAC6-selective compounds in neuroblasts. Representative results are shown here with the standard HDAC inhibitors trichostatin A (non-specific), MS275 (HDAC1-specific), and tubastatin A (HDAC6-specific) using HeLa cells.

The present method serves to identify isoform-specific inhibitors of histone deacetylases (HDAC) in HeLa cells by the UHPLC-MS analysis of multiple substrates. This is an antibody-free method developed to reflect HDAC1 and HDAC6 activity in the living cell environment, in contrast to single-isoform cell-free assays.

Mesure simultanée de HDAC1 et de HDAC6 activité en HeLa cellules utilisant UHPLC-MS

The search for new histone deacetylase (HDAC) inhibitors is of increasing interest in drug discovery. Isoform selectivity has been in the spotlight since ...

DNA-magnetic Particle Binding Analysis by Dynamic and Electrophoretic Light Scattering

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the evaluation of DNA-magnetic particles binding via dynamic light scattering (DLS) and electrophoretic light scattering (ELS). Analysis by DLS provides valuable information on the physicochemical properties of particles including particle size, polydispersity, and zeta potential. The latter describes the surface charge of the particle which plays major role in electrostatic binding of materials such as DNA. Here, a comparative analysis exploits three chemical modifications of nanoparticles and microparticles and their effects on DNA binding and elution. Chemical modifications by branched polyethylenimine, tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane are investigated. Since DNA exhibits a negative charge, it is expected that zeta potential of particle surface will decrease upon binding of DNA. Forming of clusters should also affect particle size. In order to investigate the efficiency of these particles in isolation and elution of DNA, the particles are mixed with DNA in low pH (~6), high ionic strength and dehydration environment. Particles are washed on magnet and then DNA is eluted by Tris-HCl buffer (pH = 8). DNA copy number is estimated using quantitative polymerase chain reaction (PCR). Zeta potential, particle size, polydispersity and quantitative PCR data are evaluated and compared. DLS is an insightful and supporting method of analysis that adds a new perspective to the process of screening of particles for DNA isolation.

This protocol describes the synthesis of magnetic particles and evaluation of their DNA-binding properties via dynamic and electrophoretic light scattering. This method focuses on monitoring changes in particle size, their polydispersity and zeta potential of particle surface which play major role in binding of materials such as DNA.

ADN-magnétoscopie liaison analyse par diffusion de la lumière dynamique et électrophorèse

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the ...

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

Démêler les fibres d’aramide de copolymère haute résistance afin de permettre la détermination de leurs propriétés mécaniques

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

Technical Aspect of the Automated Synthesis and Real-Time Kinetic Evaluation of [11C]SNAP-7941

Positron emission tomography (PET) is an essential molecular imaging technique providing insights into pathways and using specific targeted radioligands for in vivo investigations. Within this protocol, a robust and reliable remote-controlled radiosynthesis of [11C]SNAP-7941, an antagonist to the melanin-concentrating hormone receptor 1, is described. The radiosynthesis starts with cyclotron produced [11C]CO2 that is subsequently further reacted via a gas-phase transition to [11C]CH3OTf. Then, this reactive intermediate is introduced to the precursor solution and forms the respective radiotracer. Chemical as well as the radiochemical purity are determined by means of RP-HPLC, routinely implemented in the radiopharmaceutical quality control process. Additionally, the molar activity is calculated as it is a necessity for the following real-time kinetic investigations. Furthermore, [11C]SNAP-7941 is applied to MDCKII-WT and MDCKII-hMDR1 cells for evaluating the impact of P-glycoprotein (P-gp) expression on cell accumulation. For this reason, the P-gp expressing cell line (MDCKII-hMDR1) is either used without or with blocking prior to experiments by means of the P-gp substrate (&#177;)-verapamil and the results are compared to the ones observed for the wildtype cells. The overall experimental approach demonstrates the importance of a precise time-management that is essential for every preclinical and clinical study using PET tracers radiolabelled with short-lived nuclides, such as carbon-11 (half-life: 20 min).

Technical Aspect of the Automated Synthesis and Real-Time Kinetic Evaluation of [11C]SNAP-7941

Here, we represent a protocol for the fully automated radiolabelling of [11C]SNAP-7941 and the analysis of the real-time kinetics of this PET-tracer on P-gp expressing and non-expressing cells.

Aspect technique de la synthèse automatisée et de l'évaluation cinétique en temps réel de [11C]SNAP-7941

Positron emission tomography (PET) is an essential molecular imaging technique providing insights into pathways and using specific targeted radioligands ...

Quantitative Atomic-Site Analysis of Functional Dopants/Point Defects in Crystalline Materials by Electron-Channeling-Enhanced Microanalysis

A novel elemental and chemical analysis scheme based on electron-channeling phenomena in crystalline materials is introduced, where the incident high-energy electron beam is rocked with the submicrometric pivot point fixed on a specimen. This method enables us to quantitatively derive the site occupancies and site-dependent chemical information of impurities or intentionally doped functional elements in a specimen, using energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy attached to a scanning transmission electron microscope, which is of significant interest to current materials science, particularly related to nanotechnologies. This scheme is applicable to any combination of elements even when the conventional Rietveld analysis by X-ray or neutron diffraction occasionally fails to provide the desired results because of limited sample sizes and close scattering factors of neighboring elements in the periodic table. In this methodological article, we demonstrate the basic experimental procedure and analysis method of the present beam-rocking microanalysis.

We provide a general outline of quantitative microanalysis methods for estimating the site occupancies of impurities and their chemical states by taking advantage of electron-channeling phenomena under incident electron beam-rocking conditions, which reliably extract information from minority species, light elements, oxygen vacancies, and other point/line/planar defects.

Analyse quantitative de site atomique de dopants fonctionnels/défauts ponctuels dans des matériaux cristallins par microanalyse améliorée par canalisation électronique