Nous tenons à remercier le financement de la DARPA parrainé Micro Focus / Nano Fluidics Fundamentals (MF3) Centre sous le numéro N66001-10-1-4003, et de la DARPA subvention N660001-09-C-2082.

<ol>
	<li>Jung, B., Bharadwaj, R., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On-chip+millionfold+sample+stacking+using+transient+isotachophoresis.">On-chip millionfold sample stacking using transient isotachophoresis.</a> Anal. Chem. 78 (7), 2319-2319 (2006).</li><li>Jung, B., Zhu, Y., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+100+am+fluorophores+using+a+high-sensitivity+on-chip+CE+system+and+transient+isotachophoresis.">Detection of 100 am fluorophores using a high-sensitivity on-chip CE system and transient isotachophoresis.</a> Anal. Chem. 79 (1), 345-345 (2007).</li><li>Everaerts, F. M., Beckers, J. L., Verheggen, T. P. E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isotachophoresis:+Theory,+instrumentation,+and+applications.">Isotachophoresis: Theory, instrumentation, and applications.</a> Elsevier Science &#38; Technology. , (1976).</li><li>Khurana, T. K., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preconcentration,+separation,+and+indirect+detection+of+nonfluorescent+analytes+using+fluorescent+mobility+markers.">Preconcentration, separation, and indirect detection of nonfluorescent analytes using fluorescent mobility markers.</a> Anal. Chem. 80 (1), 279-279 (2008).</li><li>Bercovici, M., Kaigala, G. V., Backhouse, C. J., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+carrier+ampholytes+assay+for+portable,+label-free+detection+of+chemical+toxins+in+tap+water.">Fluorescent carrier ampholytes assay for portable, label-free detection of chemical toxins in tap water.</a> Anal. Chem. 82 (5), 1858-1858 (2010).</li><li>Bercovici, M., Kaigala, G. V., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+for+analyte+identification+using+isotachophoresis+and+a+fluorescent+carrier+ampholyte+assay.">Method for analyte identification using isotachophoresis and a fluorescent carrier ampholyte assay.</a> Anal. Chem. 82 (5), 2134-2134 (2010).</li><li>Kaigala, G. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miniaturized+system+for+isotachophoresis+assays.">Miniaturized system for isotachophoresis assays.</a> Lab Chip. 10 (17), 2242-2242 (2010).</li><li>Chambers, R. D., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+and+quantification+of+isotachophoresis+zones+using+nonfocusing+fluorescent+tracers.">Imaging and quantification of isotachophoresis zones using nonfocusing fluorescent tracers.</a> Anal. Chem. 81 (8), 3022-3022 (2009).</li><li>Schoch, R. B., Ronaghi, M., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+selective+extraction,+isolation,+preconcentration,+and+quantitation+of+small+RNAs+from+cell+lysate+using+on-chip+isotachophoresis.">Rapid and selective extraction, isolation, preconcentration, and quantitation of small RNAs from cell lysate using on-chip isotachophoresis.</a> Lab Chip. 9 (15), 2145-2145 (2009).</li><li>Persat, A., Marshall, L. A., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+nucleic+acids+from+whole+blood+using+isotachophoresis.">Purification of nucleic acids from whole blood using isotachophoresis.</a> Anal. Chem. 81 (22), 9507-9507 (2009).</li><li>Bercovici, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+detection+of+urinary+tract+infections+using+isotachophoresis+and+molecular+beacons.">Rapid detection of urinary tract infections using isotachophoresis and molecular beacons.</a> Anal. Chem. 83 (11), 4110-4110 (2011).</li><li>Marshall, L. A., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extraction+of+DNA+from+malaria-infected+erythrocytes+using+isotachophoresis.">Extraction of DNA from malaria-infected erythrocytes using isotachophoresis.</a> Anal. Chem. 83 (24), 9715-9715 (2011).</li><li>Persat, A., Chambers, R. D., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+principles+of+electrolyte+chemistry+for+microfluidic+electrokinetics.+Part+I:+Acid-base+equilibria+and+pH+buffers.">Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part I: Acid-base equilibria and pH buffers.</a> Lab Chip. 9 (17), 2437-2437 (2009).</li><li>Garcia-Schwarz, G., Bercovici, M., Marshall, L. A., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sample+dispersion+in+isotachophoresis.">Sample dispersion in isotachophoresis.</a> J. Fluid Mech. 1 (1), 1-1 (2011).</li><li>Kohlrausch, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#220;ber+concentrations-verschiebungen+durch+electrolyse+im+inneren+von+l&#214;sungen+und+l&#214;sungsgemischen.">&#220;ber concentrations-verschiebungen durch electrolyse im inneren von l&#214;sungen und l&#214;sungsgemischen.</a> Ann. Phys. 298 (10), 209-209 (1897).</li><li>Alberty, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Moving+boundary+systems+formed+by+weak+electrolytes.+Theory+of+simple+systems+formed+by+weak+acids+and+bases.">Moving boundary systems formed by weak electrolytes. Theory of simple systems formed by weak acids and bases.</a> J. Am. Chem. Soc. 72 (6), 2361-2361 (1950).</li><li>Jovin, 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=Multiphasic+zone+electrophoresis.+I.+Steady-state+moving-boundary+systems+formed+by+different+electrolyte+combinations.">Multiphasic zone electrophoresis. I. Steady-state moving-boundary systems formed by different electrolyte combinations.</a> Biochem. 12 (5), 871-871 (1973).</li><li>Persat, A., Santiago, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA+profiling+by+simultaneous+selective+isotachophoresis+and+hybridization+with+molecular+beacons.">MicroRNA profiling by simultaneous selective isotachophoresis and hybridization with molecular beacons.</a> Anal. Chem. , (2011).</li></ol>

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Les méthodes présentées ici ITP permettre la détection rapide, sensible et robuste et la manipulation des molécules ioniques. Le principal défi dans l&#39;utilisation de PTI est un choix approprié de tampons LE et TE. Dans le PTI anionique, nous choisissons généralement que l&#39;anion chlorure de premier plan, car il est un acide fort avec une mobilité absolue très élevée et donc a des propriétés très prévisibles. Par conséquent, le choix de mémoire tampon dans anionique ITP est généralement réduit à choisir un bon TE et contre-ion. Pour sélectifs des expériences axées, le choix TE est essentiel à l&#39;exclusion de contamination des ions. Dans les applications où les contaminants ne sont pas présents, inférieure TE mobilité efficace accélère le taux de mise au point. Nous vous recommandons d&#39;utiliser ce qui suit, relativement bien comportés-anioniques ions TE: MES, MOPS, HEPES, tricine. Choix de contre-ion affecte à la fois le pH du système et TE de mobilité efficace. Contre-courants sont tris (pKa 8,1) et de bis-tris (pKa 6,4). Pour les essais nécessitant un pH inférieur ou supérieur, nous vous recommandons la pyridine (pKa 5,25) etéthanolamine (pKa 9,5), respectivement. Dans les tableaux 1 et 2, pour le PTI anioniques et cationiques, respectivement, nous résumons plusieurs exemples de tampons utiles. Nous prenons HCl comme l&#39;ion anionique LE et de sodium comme ions cationique LE, et nous n&#39;assumons 100 mm Résistance ionique du tampon LE. Le lecteur notera que la force ionique du tampon dans nos protocoles (et dans les tableaux 1-2) est toujours supérieure ou égale à 10 mM. Si, en théorie de la physique des ITP s&#39;applique à une force ionique inférieure à 10 mM, contaminants naturels (par exemple l&#39;acide carbonique provenant de la réaction entre l&#39;eau et du dioxyde de carbone atmosphérique) près du niveau 1 mM limitent souvent l&#39;utilisation pratique de faibles tampons de force ionique. Nous notons que le mécanisme de transduction du signal ne se limite pas aux essais présentés dans ce protocole. Comme nous l&#39;avons brièvement dans la partie 5, en mode plateau purifié zones peuvent être détectées par les changements de conductivité locale, ABSORPTION UVBance, la température, ou d&#39;un indice de réfraction. Dans notre propre groupe, nous avons développé une méthode qui utilise des ampholytes porteurs fluorescents pour la détection sensible et l&#39;identification des analytes inconnus. 5 Dans des expériences de mode de pointe, des sondes spécifiques peuvent être utilisés pour étiqueter les analytes ciblés. Dans un exemple, nous utilisons des balises moléculaires - des sondes oligonucléotidiques qui sont fluorescents lors de l&#39;hybridation à leur séquence cible - pour détecter l&#39;ADN cible ou des molécules d&#39;ARN avec une grande spécificité 11,18. Bien que le PTI est relativement robuste à la dispersion causée par la pression axée débit et EOF, EOF excessive peut conduire à la stagnation de l&#39;interface ITP, où la vitesse moyenne EOF devient égale à la vitesse ITP 14. EOF Cette forte se produit surtout dans des conditions de pH élevé et la force ionique faible. Pour cette raison, nous recommandons l&#39;utilisation de tampons avec un pH de 8 ou moins, et avec la force ionique de l&#39;ordre de 100 mm si commode. Dans notre expérience, PVP est leplus de revêtement efficace pour la suppression EOF en jetons de borosilicate. Toutefois, en raison de ses propriétés de tamisage, le PVP peut ne pas être approprié pour certaines applications, telles que se concentrer l&#39;ADN génomique. Dans les expériences, nous observons que l&#39;ajout de PVP peut réduire considérablement la mobilité ADN génomique absolue (au point où il ne se concentre pas). Dans ces cas, un revêtement silanol tels que Sigmacote en conjonction avec un agent tensio-actif (par exemple Triton X-100) peut également être efficace dans la réduction de EOF 10. <table border="1"><tbody><tr><td></td><td colspan="4"> Anion TE (pKa -1) </td></tr><tr><td> Contre-ion tampon (pKa +1) </td><td> MES (6,10) </td><td> MOPS (7,20) </td><td> HEPES (7,50) </td><td> tricine (8.15) </td></tr><tr><td> éthanolamine (9.50) </td><td> 21,41 </td><td> 20,40 </td><td> 17,38 </td><td> 22,85 </td></tr><tr><td> tris (8,08) </td><td> 21,00 </td><td> 19,23 &lt;/ Td&gt; <td> 15,84 </td><td> 17,56 </td></tr><tr><td> bis-tris (6,40) </td><td> 18,22 </td><td> 10,41 </td><td> 7,30 </td><td> 5,23 </td></tr><tr><td> pyridine (5.18) </td><td> 1,01 </td><td> 3,72 </td><td> 2,42 </td><td> 1,48 </td></tr></tbody></table> Tableau 1. L&#39;ampleur de mobilité effective (× 10 -9 m 2 / V / s) de la zone analyte pure corrigée dans ITP anionique où la LE est de 100 mm et 200 contre-HCl tampon mM. <table border="1"><tbody><tr><td></td><td colspan="4"> Cation TE (pKa +1) </td></tr><tr><td> Contre-ion tampon (pKa -1) </td><td> éthanolamine (9.50) </td><td> tris (8,08) </td><td> bis-tris (6,40) </td><td> pyridine (5.18) </td></tr><tr><td> MES (6,10) </td><td> 35,57 </td><td> 21,96 </td><td> 16,39 </td><td> 10,45 </td></tr><tr><td> MOPS (7.20) </td><td> 35,47 </td><td> 20,92 </td><td> 9,76 </td><td> 3,93 </td></tr><tr><td> HEPES (7,50) </td><td> 35,35 </td><td> 19,97 </td><td> 7,77 </td><td> 2,88 </td></tr><tr><td> Tricine (8.15) </td><td> 34,77 </td><td> 16,72 </td><td> 4,50 </td><td> 1,44 </td></tr></tbody></table> Tableau 2. L&#39;ampleur de mobilité effective (× 10 -9 m 2 / V / s) de la zone analyte pure corrigée dans ITP cationique où le LE est de 100 mM de sodium et 200 mM tampon contre-ion.

<table border="1"><tbody><tr><td colspan="4"> REACTIFS </td></tr><tr><td> Nom </td><td> Entreprise </td><td> Numéro de catalogue </td><td> Commentaires </td></tr><tr><td> L&#39;eau distillée </td><td> GIBCO </td><td> 10977 </td><td> RNase / DNase </td></tr><tr><td> Clorox Ultra </td><td> Clorox </td><td> 02489CT </td><td></td></tr><tr><td> l&#39;hydroxyde de sodium (NaOH) </td><td> Mallinckrodt </td><td> 7708 </td><td></td></tr><tr><td> de l&#39;acide chlorhydrique (HCl) </td><td> EMD Chemicals </td><td> HX0603-4 </td><td></td></tr><tr><td> Trizma de base (tris) </td><td> Sigma-Aldrich </td><td> T6066 </td><td></td></tr><tr><td> polyvinylpyrrolidone (PVP) </td><td> Polysciences Inc </td><td> 06067 </td><td> MW 1000000 </td></tr><tr><td> HEPES </td><td> Sigma-Aldrich </td><td> H-4034 </td><td></td></tr><tr><td> Alexa Fluor 488 d&#39;acide carboxylique </td><td> Invitrogen </td><td> A20000 </td><td></td></tr><tr><td> tricine </td><td> Sigma-Aldrich </td><td> T-9784 </td><td></td></tr><tr><td> bis-tris </td><td> Sigma-Aldrich </td><td> B4429 </td><td></td></tr><tr><td> EDTA </td><td> GIBCO </td><td> AM9260G </td><td></td></tr><tr><td> Triton X-100 </td><td> Sigma-Aldrich </td><td> X100 </td><td></td></tr><tr><td> lysozyme </td><td> Sigma-Aldrich </td><td> L6876 </td><td></td></tr><tr><td> SYBR Green II </td><td> Invitrogen </td><td> S7564 </td><td></td></tr><tr><td> éthanolamine </td><td> Sigma-Aldrich </td><td> 411000 </td><td></td></tr><tr><td> Rhodamine 6G </td><td> Acros Organics (Geel, Belgique) </td><td> CAS 989-38-8 </td><td></td></tr><tr><td> L-aminoacides </td><td> Sigma-Aldrich </td><td> LAA21 </td><td></td></tr><tr><td> Puissance SYBR Green ARN-to-C T 1-Step Kit </td><td> Applied Biosystems </td><td> 4389986 </td><td></td></tr><tr> &lt;td&gt; amorces de PCR </td><td> Integrated DNA Technologies </td><td></td><td></td></tr><tr><td colspan="4"> ÉQUIPEMENT </td></tr><tr><td> Nom </td><td> Entreprise </td><td> Numéro de catalogue </td><td> Commentaires </td></tr><tr><td> Borosilicate puce microfluidique </td><td> Caliper Life Sciences Inc </td><td> NS12A </td><td> Livré avec ou sans plastique caddy </td></tr><tr><td> Pompe à vide </td><td> Gast </td><td> DOA-P104-AA </td><td></td></tr><tr><td> SourceMeter </td><td> Keithley </td><td> 2410 </td><td> Constant courants et constants modes de fonctionnement de tension </td></tr><tr><td> Microscope inversé à épifluorescence </td><td> Olympe </td><td> IX70 </td><td> Utilisez lampe au mercure (Olympus) ou LED (Thorlabs) pour l&#39;éclairage </td></tr><tr><td> Filtre cube </td><td> Oméga </td><td> XF115-2 </td><td> Excitation / émission: bleu / vert </td></tr><tr><td> Coffre-fort-Verrouiller microtubes </td><td> Eppendorf </td><td> 022363204 </td><td> Une capacité de 1,5 mL </td></tr><tr><td> Centrifuger </td><td> Eppendorf </td><td> 5417C </td><td></td></tr></tbody></table> Tableau 3. Réactifs et équipements spécifiques.

on-chip isotachophoresis for separation of ions and purification of nucleic acids

Techniques électrocinétiques sont un aliment de base des applications à micro-en raison de leur capacité unique d&#39;effectuer une variété de processus fluidiques et électrophorétique dans des systèmes simples et compacts sans pièces mobiles. Isotachophorèse (PTI) est une technique simple et très robuste qui peut atteindre électrocinétique de séparation 1,2 million de fois préconcentration et efficace et d&#39;extraction basée sur la mobilité ionique. 3 Par exemple, nous avons démontré l&#39;application du PTI à la séparation et la détection sensible de non marqué molécules ioniques (par exemple les toxines, de l&#39;ADN, d&#39;ARNr, miRNA) avec peu ou pas de préparation de l&#39;échantillon 4-8 et à l&#39;extraction et la purification des acides nucléiques à partir des matrices complexes, y compris la culture cellulaire, de l&#39;urine et le sang. 9-12 PTI réalise focalisation et de séparation utilisant un champ électrique appliqué et deux tampons de canal dans un système fluidique. Pour les analytes anioniques, le premier électrolyte (LE) tampon est choisi sette que ses anions ont une plus grande mobilité électrophorétique effective que les anions de l&#39;électrolyte de fuite (TE) du tampon (mobilité efficace décrit la vitesse de dérive observable d&#39;un ion et prend en compte l&#39;état d&#39;ionisation de l&#39;ion, tel que décrit en détail par Persat et al . 13). Après l&#39;établissement d&#39;une interface entre les électrodes en tungstène et LE, un champ électrique est appliqué de telle sorte que les ions LE s&#39;éloigner de la région occupée par des ions TE. Ions de l&#39;échantillon de la race la mobilité efficace intermédiaire avant d&#39;ions TE, mais ne peut pas dépasser ions LE, et aussi ils se concentrent à l&#39;interface LE-TE (ci-après dénommé l &#39;«interface ITP&quot;). En outre, le TE et les zones de formulaire de la conductivité LE respectivement basse et haute, qui établissent un gradient de champ raide électrique à l&#39;interface ITP. Ce gradient de champ des pré-espèces des échantillons car ils se concentrent. Le bon choix des résultats TE et LE dans la focalisation et la purification des espèces cibles à partir d&#39;autres non-ciblées espèces et, finalement, la séparation uneségrégation des espèces d-échantillon. Nous revoyons ici le PTI physique principes qui sous-tend et de discuter de deux modes de fonctionnement: standard &quot;de pointe&quot; et &quot;plateau&quot; modes. En mode de pointe, relativement diluée ions de l&#39;échantillon se concentrer ensemble au sein de chevauchement des pics étroits à l&#39;interface ITP. En mode plateau, ions de l&#39;échantillon plus abondantes atteindre une concentration en régime permanent et séparer en adjacentes plateau-comme zones ordonnées par leur mobilité efficace. Modes de pointe et le plateau se posent sur les mêmes sous-jacents de physique, mais représentent des régimes distincts différenciés par la concentration de l&#39;analyte initiale et / ou la quantité de temps alloué pour l&#39;accumulation de l&#39;échantillon. Nous avons d&#39;abord décrire en détail une expérience en mode modèle de pointe et alors démontrer un essai en mode de pointe pour l&#39;extraction des acides nucléiques à partir de E. la culture de cellules Escherichia. Nous concluons en présentant une analyse en mode plateau, où nous utilisons un non-focalisation traceur (NFT) espèces de visualiser la séparation et parformer quantification d&#39;acides aminés.

Watch this Scientific Journal Video about On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids at JoVE.com

On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids

Isotachophorèse (PTI) est une séparation solide électrocinétique et de la technique de préconcentration avec des applications allant de la détection de la toxine à la préparation des échantillons. Nous passons en revue les principes physiques de l&#39;ITP et la méthodologie de l&#39;application de cette technique à deux exemples d&#39;applications spécifiques: la séparation et la détection de petites molécules et de purification des acides nucléiques à partir de lysat de culture cellulaire.

Sur la puce isotachophorèse pour la séparation des ions et purification des acides nucléiques

Electrokinetic techniques are a staple of microscale applications because of their unique ability to perform a variety of fluidic and electrophoretic ...

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24.2K vues.  Stanford University. Isotachophorèse (PTI) est une séparation solide électrocinétique et de la technique de préconcentration avec des applications allant de la détection de la toxine à la préparation des échantillons. Nous passons en revue les principes physiques de l'ITP et la méthodologie de l'application de cette technique à deux exemples d'applications spécifiques: la séparation et la détection de petites molécules et de purification des acides nucléiques à pa...

Vidéo: On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids

Fabrication of Electrochemical-DNA Biosensors for the Reagentless Detection of Nucleic Acids, Proteins and Small Molecules

As medicine is currently practiced, doctors send specimens to a central laboratory for testing and thus must wait hours or days to 
receive the results. Many patients would be better served by rapid, bedside tests. To this end our laboratory and others have developed a versatile, reagentless 
biosensor platform that supports the quantitative, reagentless, electrochemical detection of nucleic acids (DNA, RNA), proteins (including antibodies) and small 
molecules analytes directly in unprocessed clinical and environmental samples. In this video, we demonstrate the preparation and use of several biosensors in this 
"E-DNA" class. In particular, we fabricate and demonstrate sensors for the detection of a target DNA sequence in a polymerase chain reaction mixture, an HIV-specific antibody and the drug cocaine. The preparation procedure requires only three hours of hands-on effort followed by an overnight incubation, and their use requires only minutes.

"E-DNA" sensors, reagentless, electrochemical biosensors that perform well even when challenged directly in blood and other complex matrices, have been adapted to the detection of a wide range of nucleic acid, protein and small molecule analytes. Here we present a general procedure for the fabrication and use of such sensors.

La fabrication des électrochimique de l&#39;ADN des Biocapteurs pour la détection sans réactif d&#39;acides nucléiques, protéines et petites molécules

As medicine is currently practiced, doctors send specimens to a central laboratory for testing and thus must wait hours or days to 
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Lensfree On-chip Tomographic Microscopy Employing Multi-angle Illumination and Pixel Super-resolution

Tomographic imaging has been a widely used tool in medicine as it can provide three-dimensional (3D) structural information regarding objects of different size scales. In micrometer and millimeter scales, optical microscopy modalities find increasing use owing to the non-ionizing nature of visible light, and the availability of a rich set of illumination sources (such as lasers and light-emitting-diodes) and detection elements (such as large format CCD and CMOS detector-arrays). Among the recently developed optical tomographic microscopy modalities, one can include optical coherence tomography, optical diffraction tomography, optical projection tomography and light-sheet microscopy. 1-6 These platforms provide sectional imaging of cells, microorganisms and model animals such as C. elegans, zebrafish and mouse embryos.
Existing 3D optical imagers generally have relatively bulky and complex architectures, limiting the availability of these equipments to advanced laboratories, and impeding their integration with lab-on-a-chip platforms and microfluidic chips. To provide an alternative tomographic microscope, we recently developed lensfree optical tomography (LOT) as a high-throughput, compact and cost-effective optical tomography modality. 7 LOT discards the use of lenses and bulky optical components, and instead relies on multi-angle illumination and digital computation to achieve depth-resolved imaging of micro-objects over a large imaging volume. LOT can image biological specimen at a spatial resolution of &lt;1 &mu;m x &lt;1 &mu;m x &lt;3 &mu;m in the x, y and z dimensions, respectively, over a large imaging volume of 15-100 mm3, and can be particularly useful for lab-on-a-chip platforms.

Lensfree optical tomography is a three-dimensional microscopy technique that offers a spatial resolution of &lt;1 &mu;m &times; &lt;1 &mu;m &times; &lt;3 &mu;m in x, y and z dimensions, respectively, over a large imaging-volume of 15-100 mm3, which can be particularly useful for integration with lab-on-a-chip platforms.

Lensfree sur puce microscopie tomographique Employant multi-angle d&#39;éclairage et de Pixel Super-résolution

Tomographic imaging has been a widely used tool in medicine as it can provide three-dimensional (3D) structural information regarding objects of different ...

On-Chip Endothelial Inflammatory Phenotyping

Atherogenesis is potentiated by metabolic abnormalities that contribute to a heightened state of systemic inflammation resulting in endothelial dysfunction. However, early functional changes in endothelium that signify an individual's level of risk are not directly assessed clinically to help guide therapeutic strategy. Moreover, the regulation of inflammation by local hemodynamics contributes to the non-random spatial distribution of atherosclerosis, but the mechanisms are difficult to delineate in vivo. We describe a lab-on-a-chip based approach to quantitatively assay metabolic perturbation of inflammatory events in human endothelial cells (EC) and monocytes under precise flow conditions. Standard methods of soft lithography are used to microfabricate vascular mimetic microfluidic chambers (VMMC), which are bound directly to cultured EC monolayers.1 These devices have the advantage of using small volumes of reagents while providing a platform for directly imaging the inflammatory events at the membrane of EC exposed to a well-defined shear field. We have successfully applied these devices to investigate cytokine-,2 lipid-3, 4 and RAGE-induced5 inflammation in human aortic EC (HAEC). Here we document the use of the VMMC to assay monocytic cell (THP-1) rolling and arrest on HAEC monolayers that are conditioned under differential shear characteristics and activated by the inflammatory cytokine TNF-&alpha;. Studies such as these are providing mechanistic insight into atherosusceptibility under metabolic risk factors.

Microfluidic flow chambers etched by photolithography and fabricated from PDMS are applied to probe functional outcomes associated with EC dysfunction and inflammation. In a representative experiment, the ability of differential shear stress to modulate monocytic cell adhesion to cytokine activated EC monolayers is demonstrated.

On-Chip phénotypage endothélium inflammatoire

Atherogenesis is potentiated by metabolic abnormalities that contribute to a heightened state of systemic inflammation resulting in endothelial ...

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An easy-to-use and low-cost sensor platform is highly desired to measure various types of analytes (e.g., biomarkers, hormones, and drugs) quantitatively and specifically. For this reason, dry film photoresist technology - enabling cheap, facile, and high-throughput fabrication - was used to manufacture the microfluidic biosensor presented here. Depending on the bioassay used afterwards, the versatile platform is capable of detecting various types of biomolecules. For the fabrication of the device, platinum electrodes are structured on a flexible polyimide (PI) foil in the only clean-room process step. The PI foil serves as a substrate for the electrodes, which are insulated with an epoxy-based photoresist. The microfluidic channel is subsequently generated by the development and lamination of dry film photoresist (DFR) foils onto the PI wafer. By using a hydrophobic stopping barrier in the channel, the channel is separated into two specific areas: an immobilization section for the enzyme-linked assay and an electrochemical measurement cell for the amperometric signal readout.
The on-chip bioassay immobilization is performed by the adsorption of the biomolecules to the channel surface. The glucose oxidase enzyme is used as a transducer for electrochemical signal generation. In the presence of the substrate, glucose, hydrogen peroxide is produced, which is detected at the platinum working electrode. The stop-flow technique is applied to obtain signal amplification along with rapid detection. Different biomolecules can quantitatively be measured by means of the introduced microfluidic system, giving an indication of different types of diseases, or, in regard to therapeutic drug monitoring, facilitating a personalized therapy.

A microfluidic biosensor platform was designed and fabricated using low-cost dry film photoresist technology for the rapid and sensitive quantification of various analytes. This single-use system allows for the electrochemical readout of on-chip-immobilized enzyme-linked assays by means of the stop-flow technique.

Feuil sec axée sur la résine photosensible de biocapteurs microfluidiques électrochimiques plate-forme : Fabrication de dispositifs, préparation de dosage sur puce et fonctionnement du système

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An ...

Fabrication and Validation of an Organ-on-chip System with Integrated Electrodes to Directly Quantify Transendothelial Electrical Resistance

Organs-on-chips, in vitro models involving the culture of (human) tissues inside microfluidic devices, are rapidly emerging and promise to provide useful research tools for studying human health and disease. To characterize the barrier function of cell layers cultured inside organ-on-chip devices, often transendothelial or transepithelial electrical resistance (TEER) is measured. To this end, electrodes are usually integrated into the chip by micromachining methods to provide more stable measurements than is achieved with manual insertion of electrodes into the inlets of the chip. However, these electrodes frequently hamper visual inspection of the studied cell layer or require expensive cleanroom processes for fabrication. To overcome these limitations, the device described here contains four easily integrated electrodes that are placed and fixed outside of the culture area, making visual inspection possible. Using these four electrodes the resistance of six measurement paths can be quantified, from which the TEER can be directly isolated, independent of the resistance of culture medium-filled microchannels. The blood-brain barrier was replicated in this device and its TEER was monitored to show the device applicability. This chip, the integrated electrodes and the TEER determination method are generally applicable in organs-on-chips, both to mimic other organs or to be incorporated into existing organ-on-chip systems.

This publication describes the fabrication of an organ-on-chip device with integrated electrodes for direct quantification of transendothelial electrical resistance (TEER). For validation, the blood-brain barrier was mimicked inside this microfluidic device and its barrier function was monitored. The presented methods for electrode integration and direct TEER quantification are generally applicable.

Fabrication et Validation d’un système d’orgue-on-chip avec électrodes intégrées à quantifier directement transendothéliale résistance électrique

Organs-on-chips, in vitro models involving the culture of (human) tissues inside microfluidic devices, are rapidly emerging and promise to provide useful ...

Visual Detection of Multiple Nucleic Acids in a Capillary Array

Multi-target, short time, and resource-affordable methodologies for the detection of multiple nucleic acids in a single, easy to operate test are urgently needed in disease diagnosis, microbial monitoring, genetically modified organism (GMO) detection, and forensic analysis. We have previously described the platform called CALM (Capillary Array-based Loop-mediated isothermal amplification for Multiplex visual detection of nucleic acids). Herein, we describe improved fabrication and performance processes for this platform. Here, we apply a small, ready-to-use cassette assembled by capillary array for multiplex visual detection of nucleic acids. The capillary array is pre-treated into a hydrophobic and hydrophilic pattern before fixing loop-mediated isothermal amplification (LAMP) primer sets in capillaries. After assembly of the loading adaptor, LAMP reaction mixture is loaded and isolated into each capillary, due to capillary force by a single pipetting step. The LAMP reactions are performed in parallel in the capillaries. The results are visually read out by illumination with a hand-held UV flashlight. Using this platform, we demonstrate monitoring of 8 frequently appearing elements and genes in GMO samples with high specificity and sensitivity. In summary, the platform described herein is intended to facilitate the detection of multiple nucleic acids. We believe it will be widely applicable in fields where high-throughput nucleic acid analysis is required.

This protocol describes the fabrication of a small, ready-to-use cassette that can be applied for visual detection of multiple nucleic acids in a single, test that is easy to operate. In this approach, a capillary array was used for multiplex and highly efficient detection of GMO targets.

Détection visuelle de plusieurs acides nucléiques dans une gamme capillaire

Multi-target, short time, and resource-affordable methodologies for the detection of multiple nucleic acids in a single, easy to operate test are urgently ...

Preparation, Purification, and Use of Fatty Acid-containing Liposomes

Liposomes containing single-chain amphiphiles, particularly fatty acids, exhibit distinct properties compared to those containing diacylphospholipids due to the unique chemical properties of these amphiphiles. In particular, fatty acid liposomes enhance dynamic character, due to the relatively high solubility of single-chain amphiphiles. Similarly, liposomes containing free fatty acids are more sensitive to salt and divalent cations, due to the strong interactions between the carboxylic acid head groups and metal ions. Here we illustrate techniques for preparation, purification, and use of liposomes comprised in part or whole of single chain amphiphiles (e.g., oleic acids).

Liposomes containing single-chain amphiphiles, particularly fatty acids, exhibit distinct properties compared to those containing diacylphospholipids due to the unique chemical properties of single chain amphiphiles. Here we describe techniques for the preparation, purification, and use of liposomes comprised in part or whole of these amphiphiles.

Préparation, Purification et l’utilisation de Liposomes contenant de l’acide gras

Liposomes containing single-chain amphiphiles, particularly fatty acids, exhibit distinct properties compared to those containing diacylphospholipids due ...

Simultaneous Quantification of Selected Kynurenines Analyzed by Liquid Chromatography-Mass Spectrometry in Medium Collected from Cancer Cell Cultures

The kynurenine pathway and the tryptophan catabolites called kynurenines have received increased attention for their involvement in immune regulation and cancer biology. An in vitro cell culture assay is often used to learn about the contribution of different tryptophan catabolites in a disease mechanism and for testing therapeutic strategies. Cell culture medium that is rich in secreted metabolites and signaling molecules reflects the status of tryptophan metabolism and other cellular events. New protocols for the reliable quantification of multiple kynurenines in the complex cell culture medium are desired to allow for a reliable and quick analysis of multiple samples. This can be accomplished with liquid chromatography coupled with mass spectrometry. This powerful technique is employed in many clinical and research laboratories for the quantification of metabolites and can be used for measuring kynurenines.
Presented here is the use of liquid chromatography coupled with single quadrupole mass spectrometry (LC-SQ) for the simultaneous determination of four kynurenines, i.e., kynurenine, 3-hydroxykynurenine, 3-hydroxyanthranilic, and xanthurenic acid in the medium collected from in vitro cultured cancer cells. SQ detector is simple to use and less expensive compared to other mass spectrometers. In the SQ-MS analysis, multiple ions from the sample are generated and separated according to their specific mass-to-charge ratio (m/z), followed by the detection using a Single Ion Monitoring (SIM) mode.
This paper draws the attention on the advantages of the reported method and indicates some weak points. It is focused on critical elements of LC-SQ analysis including sample preparation along with chromatography and mass spectrometry analysis. The quality control, method calibration conditions and matrix effect issues are also discussed. We described a simple application of 3-nitrotyrosine as one analog standard for all target analytes. As confirmed by experiments with human ovary and breast cancer cells, the proposed LC-SQ method&#160;generates reliable results and can be further applied to other in vitro cellular models.

Described here is a protocol for the determination of four different tryptophan metabolites generated in the kynurenine pathway (kynurenine, 3-hydroxykynurenine, xanthurenic acid, 3-hydroxyanthranilic acid) in the medium collected from cancer cell cultures analyzed by liquid chromatography coupled with a single quadrupole mass spectrometry.

Quantification simultanée de kynurenines sélectionnées analysées par chromatographie liquide-spectrométrie de masse dans le milieu recueilli à partir des cultures de cellules cancéreuses

The kynurenine pathway and the tryptophan catabolites called kynurenines have received increased attention for their involvement in immune regulation and ...

Self-Assembly of Gamma-Modified Peptide Nucleic Acids into Complex Nanostructures in Organic Solvent Mixtures

Current strategies in DNA and RNA nanotechnology enable the self-assembly of a variety of nucleic acid nanostructures in aqueous or substantially hydrated media. In this article, we describe detailed protocols that enable the construction of nanofiber architectures in organic solvent mixtures through the self-assembly of uniquely addressable, single-stranded, gamma-modified peptide nucleic acid (&#947;PNA) tiles. Each single-stranded tile (SST) is a 12-base &#947;PNA oligomer composed of two concatenated modular domains of 6 bases each. Each domain can bind to a mutually complimentary domain present on neighboring strands using programmed complementarity to form nanofibers that can grow to microns in length. The SST motif is made of 9 total oligomers to enable the formation of 3-helix nanofibers. In contrast with analogous DNA nanostructures, which form diameter-monodisperse structures, these &#947;PNA systems form nanofibers that bundle along their widths during self-assembly in organic solvent mixtures. Self-assembly protocols described here therefore also include a conventional surfactant, Sodium Dodecyl Sulfate (SDS), to reduce bundling effects.

This article provides protocols for the design and self-assembly of nanostructures from gamma-modified peptide nucleic acid oligomers in organic solvent mixtures.

Auto-assemblage d’acides nucléiques peptides gamma modifiés en nanostructures complexes dans des mélanges de solvants organiques

Current strategies in DNA and RNA nanotechnology enable the self-assembly of a variety of nucleic acid nanostructures in aqueous or substantially hydrated ...

On-Chip Octanol-Assisted Liposome Assembly for Bioengineering

Microfluidics is a widely used tool to generate droplets and vesicles of various kinds in a controlled and high-throughput manner. Liposomes are simplistic cellular mimics composed of an aqueous interior surrounded by a lipid bilayer; they are valuable in designing synthetic cells and understanding the fundamentals of biological cells in an in vitro fashion and are important for applied sciences, such as cargo delivery for therapeutic applications. This article describes a detailed working protocol for an on-chip microfluidic technique, octanol-assisted liposome assembly (OLA), to produce monodispersed, micron-sized, biocompatible liposomes. OLA functions similarly to bubble blowing, where an inner aqueous (IA) phase and a surrounding lipid-carrying 1-octanol phase are pinched off by surfactant-containing outer fluid streams. This readily generates double-emulsion droplets with protruding octanol pockets. As the lipid bilayer assembles at the droplet interface, the pocket spontaneously detaches to give rise to a unilamellar liposome that is ready for further manipulation and experimentation. OLA provides several advantages, such as steady liposome generation (&#62;10 Hz), efficient encapsulation of biomaterials, and monodispersed liposome populations, and requires very small sample volumes (~50 &#181;L), which can be crucial when working with precious biologicals. The study includes details on microfabrication, soft-lithography, and surface passivation, which are needed to establish OLA technology in the lab. A proof-of-principle synthetic biology application is also shown by inducing the formation of biomolecular condensates inside the liposomes via transmembrane proton flux. It is anticipated that this accompanying video protocol will facilitate the readers to establish and troubleshoot OLA in their labs.

The present protocol describes octanol-assisted liposome assembly (OLA), a microfluidic technique to generate biocompatible liposomes. OLA produces monodispersed, micron-sized liposomes with efficient encapsulation, allowing immediate on-chip experimentation. This protocol is anticipated to be particularly suitable for synthetic biology and synthetic cell research.