Cette étude a été soutenue par l&#39;accord de coopération Award AI075565 (à DAH) de l&#39;Institut national des allergies et des maladies infectieuses et par le Fonds Wendy et Ruby Ken pour l&#39;excellence en urologie pédiatrique recherche. BMC est le Judith et président Robert Winston en urologie pédiatrique.

1. Fonctionnalisation des capteurs électrochimiques <ol><li> Préparer la sonde de capture thiolée à une concentration de 0,05 um à 300 um 1,6-Hexanedithiol (HDT), 10 mM Tris-HCl, pH 8,0, 0,3 M de NaCl, 1 mM EDTA et incuber dans l&#39;obscurité à la température ambiante pendant 10 min . L&#39;incubation de la sonde de capture thiolé avec HDT assure que le groupe thiol sur la sonde de capture est réduite, ce qui entraîne des résultats plus cohérents. </li><li> Appliquer un courant d&#39;azote à l&#39;or nu 16 puce de réseau de capteurs (s) pendant 5 secondes pour éliminer l&#39;humidité et / ou de particules. </li><li> Appliquer 6 pl du mélange de sondes de capture HDT-thiolé à l&#39;électrode de travail de l&#39;ensemble 16 des capteurs du réseau de capteurs et de stocker la puce de capteur (s) dans une boîte de Petri couverte à 4 ° C pendant une nuit. Des sondes de capture thiolées se lient directement à l&#39;électrode d&#39;or à nu et la HDT agit pour empêcher suremballage des sondes de capture et de les maintenir dans une conformation étendue qui favorise l&#39;hybridation avec la cible. </li><li> Leaprès jour, laver la puce du capteur avec déminéralisée H 2 O pendant 2-3 sec et sec sous un courant d&#39;azote pendant 5 sec. </li><li> Appliquer 6 pi de 10 mM Tris-HCl, pH 8,0, 0,3 M de NaCl, 1 mM EDTA, 1 mM 6-mercapto-1-hexanol (SMI) à l&#39;électrode de travail de l&#39;ensemble des 16 capteurs et incuber pendant 50 min. Ceci et toutes les incubations de puces de capteurs qui suivent sont réalisées dans une boîte de Petri couvert à la température ambiante. MCH agit comme un agent de blocage, de remplissage dans les fentes, où la sonde de capture thiolé ou HDT n&#39;est pas présent sur la surface de l&#39;électrode. </li></ol> 2. Préparation des échantillons <ol><li> Transférer 1 ml de culture bactérienne dans la phase logarithmique de croissance (DO600 ≈ 0,1) dans un tube à centrifuger et centrifuger à 16000 g pendant 5 min. Eliminer le surnageant de culture. Le culot bactérien peut être traitée immédiatement ou stocké à -80 ° C pour une utilisation ultérieure. </li><li> Soigneusement remettre le culot bactérien dans 10 pi de 1 M NaOH en appliquant la pointe de la pipette au bottom du tube de centrifugation et de pipetage de haut en bas plusieurs fois. Incuber la suspension à température ambiante pendant 5 min. </li><li> Neutraliser le lysat bactérien en ajoutant 50 pl de 1 M tampon phosphate, pH 7,2, contenant 2,5% de sérum-albumine bovine mM (BSA) et 0,25 d&#39;une sonde de détection de fluorescéine modifié. Incuber le lysat neutralisé pendant 10 min à température ambiante. Sondes de détection fluorescéine modifiés s&#39;hybrident avec des molécules cibles d&#39;ARNr bactériens. </li></ol> 3. Capteur électrochimique Assay <ol><li> Laver le SMI de la puce du capteur avec déminéralisée H 2 O pendant 2-3 sec et sec sous un courant d&#39;azote pendant 5 sec. </li><li> Appliquer 4 de lysat bactérien neutralisé à l&#39;électrode de travail de chacun des 14 capteurs et incuber pendant 15 min. Complexes sonde-cible s&#39;hybrident détecteur de sondes de capture immobilisées thiolés. </li><li> Appliquer 4 l de 1 nM de transition oligonucléotide à 1 M tampon phosphate, pH 7,2, contenant 2,5% de BSA et 0,25 &amp;mu; M fluorescéine modifié sonde de détection à 2 capteurs de contrôle positif (utilisé pour la normalisation du signal) et incuber pendant 15 min. </li><li> Laver la puce du capteur avec déminéralisée H 2 O pendant 2-3 sec et sec sous un courant d&#39;azote pendant 5 sec. </li><li> Appliquer 4 ul de 0,5 U / ml anti-fluorescéine-HRP à 1 M tampon phosphate, pH 7,2, contenant 0,5% de caséine à l&#39;électrode de travail de l&#39;ensemble des 16 capteurs et incuber pendant 15 min. L&#39;anti-fluorescéine-HRP se lie aux sondes de détection de fluorescéine modifiés immobilisés. </li><li> Laver la puce du capteur avec déminéralisée H 2 O pendant 2-3 sec et sec sous un courant d&#39;azote pendant 5 sec. </li><li> Appliquer un film autocollant bien à la surface de la puce du capteur et la charge dans le support de la puce capteur. Pipette 50 ul de substrat TMB sur les 16 capteurs et fermer le support de puce capteur. </li><li> Obtenir amperometry et les mesures de voltampérométrie cycliques pour les 16 capteurs en utilisant le lecteur de puce Hélios. Courant ampérométrique est proportionnelle à la vitesse de TMB réduction sur la surface du capteur (voir Figure 1). </li></ol>

<ol>
	<li>Wu, J., Campuzano, S., Halford, C., Haake, D. A., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ternary+Surface+Monolayers+for+Ultrasensitive+(Zeptomole)+Amperometric+Detection+of+Nucleic+Acid+Hybridization+without+Signal+Amplification.">Ternary Surface Monolayers for Ultrasensitive (Zeptomole) Amperometric Detection of Nucleic Acid Hybridization without Signal Amplification.</a> Anal. Chem. 82, 8830-8837 (2010).</li><li>Halford, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+Antimicrobial+Susceptibility+Testing+by+Sensitive+Detection+of+Precursor+Ribosomal+RNA+Using+a+Novel+Electrochemical+Biosensing+Platform.">Rapid Antimicrobial Susceptibility Testing by Sensitive Detection of Precursor Ribosomal RNA Using a Novel Electrochemical Biosensing Platform.</a> Antimicrob. Agents Chemother. 56, (2012).</li><li>Campuzano, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ternary+monolayers+as+DNA+recognition+interfaces+for+direct+and+sensitive+electrochemical+detection+in+untreated+clinical+samples.">Ternary monolayers as DNA recognition interfaces for direct and sensitive electrochemical detection in untreated clinical samples.</a> Biosens. Bioelectron. 26, 3577-3584 (2011).</li><li>Gau, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+molecular+analysis+without+nucleic+acid+amplification.">Electrochemical molecular analysis without nucleic acid amplification.</a> Methods. 37, 73-83 (2005).</li><li>Patel, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Target+Specific+Capture+Enhances+Sensitivity+of+Electrochemical+Detection+of+Bacterial+Pathogens.">Target Specific Capture Enhances Sensitivity of Electrochemical Detection of Bacterial Pathogens.</a> J. Clin. Microbiol. 49, 4293-4296 (2011).</li><li>Mastali, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimal+probe+length+and+target+location+for+electrochemical+detection+of+selected+uropathogens+at+ambient+temperature.">Optimal probe length and target location for electrochemical detection of selected uropathogens at ambient temperature.</a> J. Clin. Microbiol. 46, 2707-2716 (2008).</li><li>Liao, J. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+electrochemical+DNA+biosensors+for+rapid+molecular+identification+of+uropathogens+in+clinical+urine+specimens.">Use of electrochemical DNA biosensors for rapid molecular identification of uropathogens in clinical urine specimens.</a> J. Clin. Microbiol. 44, 561-570 (2006).</li><li>Liao, J. C., et al. <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+advanced+electrochemical+DNA+biosensor+for+bacterial+pathogen+detection.">Development of an advanced electrochemical DNA biosensor for bacterial pathogen detection.</a> J. Mol. Diagn. 9, 158-168 (2007).</li><li>Pedrero, M., Campuzano, S., Pingarron, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electroanalytical+sensors+and+devices+for+multiplexed+detection+of+foodborne+pathogen+microorganisms.">Electroanalytical sensors and devices for multiplexed detection of foodborne pathogen microorganisms.</a> Sensors (Basel). 9, 5503-5520 (2009).</li><li>Kuralay, F., Campuzano, S., Haake, D. A., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+sensitive+disposable+nucleic+acid+biosensors+for+direct+bioelectronic+detection+in+raw+biological+samples.">Highly sensitive disposable nucleic acid biosensors for direct bioelectronic detection in raw biological samples.</a> Talanta. 85, 1330-1337 (2011).</li><li>Ecker, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ibis+T5000:+a+universal+biosensor+approach+for+microbiology.">Ibis T5000: a universal biosensor approach for microbiology.</a> Nat. Rev. Microbiol. 6, 553-558 (2008).</li><li>Casalta, J. 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Tous les auteurs sont des inventeurs sur les brevets se rapportant aux méthodes décrites. Un de ces brevets a été autorisé à Qvella Corporation. BMC et DAH ont participation dans Qvella Corporation. VG est le président de GeneFluidics, qui est le fabricant de la puce de réseau de capteurs électrochimiques, montage puce et lecteur de puce décrit dans cet article.

Le test de détection électrochimique décrite ici permet la détection rapide de cibles d&#39;acides nucléiques. La sensibilité et la spécificité dépendent en partie de l&#39;énergie libre de l&#39;hybridation cible-sonde, qui à son tour dépend de la longueur et la teneur en GC de la capture et sondes de détection. Nous effectuons généralement les étapes d&#39;hybridation à température ambiante (~ 20 ° C) 5, 6. Toutefois, les étapes d&#39;hybridation (3.2 et 3.3) peuvent également être eff...

Utiliser ARNr comme une molécule cible pour la détection et l&#39;identification bactérienne a un certain nombre d&#39;avantages. L&#39;abondance de l&#39;ARNr dans les cellules bactériennes prévoit une limite de sensibilité aussi bas que 250 bactéries par millilitre, sans la nécessité d&#39;amplification de la cible 1. ARNr bactérien contient des séquences spécifiques d&#39;espèces uniques qui sont accessibles à l&#39;hybridation avec des sondes d&#39;ADN. En conséquence, un ensemble de capteurs électrochimiques peut être utilisée pour identifier des bactéries inconnues, où chaque capteur est fonctionnalisé avec une sonde de capture spécifique d&#39;espèce différente. Capteurs de contrôle positifs doivent être inclus pour une cible d&#39;oligonucléotides synthétiques qui «ponts» de la capture et des sondes de détection pour créer un signal de calibrage interne. Les capteurs électrochimiques ont une large gamme d&#39;applications de recherche fondamentale et translationnelle. Par exemple, le dosage décrit ici a été utilisé pour mesurer précisément l&#39;effet de E. phase de croissance coli sur les RRNA et le nombre de copies pré-ARNr, qui est d&#39;un grand intérêt pour les chercheurs qui s&#39;intéressent à la physiologie bactérienne 2. La sensibilité du test de détection électrochimique est déterminé par le rapport signal sur bruit. Une variété d&#39;amplification du signal et des méthodes de réduction du bruit ont été explorées. Nous constatons que l&#39;amélioration de la chimie de la surface du capteur est essentielle pour réduire la liaison non spécifique de la sonde de détection et / ou enzyme HRP. En particulier, une monocouche mixte de alkanedithiols et mercaptohexanol a été trouvée pour réduire le fond, en recouvrant la surface de l&#39;électrode plus complètement, tout en conservant l&#39;accessibilité de la sonde de capture pour l&#39;hybridation de la cible 3. Ces traitements chimiques de surface sont particulièrement importants pour les essais portant sur des échantillons biologiques complexes.

<table border="1">
 <tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments (optional)</td>
 </tr>
 <tr>
 <td>6-mercapto-1-hexanol (MCH)</td>
 <td>Sigma</td>
 <td>451088</td>
 <td>Store at room temperature</td>
 </tr>
 <tr>
 <td>1,6-hexanedithiol (HDT)</td>
 <td>Sigma</td>
 <td>H-12005</td>
 <td>Store at room temperature</td>
 </tr>
 <tr>
 <td>Thiolated capture probes</td>
 <td>Operon</td>
 <td>N/A</td>
 <td>Store at 100 &mu;M in 0.1x TE at -20 &deg;C</td>
 </tr>
 <tr>
 <td>Fluorescein-modified detector probes</td>
 <td>Operon</td>
 <td>N/A</td>
 <td>Store at 100 &mu;M in 0.1x TE at -20 &deg;C</td>
 </tr>
 <tr>
 <td>Bridging Oligonucleotide</td>
 <td>Operon</td>
 <td>N/A</td>
 <td>Store at 100 &mu;M in 0.1x TE at -20 &deg;C</td>
 </tr>
 <tr>
 <td>Anti-Fluorescein-HRP, Fab fragments</td>
 <td>Roche</td>
 <td>11 426 346 910</td>
 <td>Store at 4 &deg;C</td>
 </tr>
 <tr>
 <td>Helios Chip Reader</td>
 <td>GeneFluidics</td>
 <td>GFR-2009</td>
 <td></td>
 </tr>
 <tr>
 <td>Sensor Chip Mount</td>
 <td>GeneFluidics</td>
 <td>GFR-003</td>
 <td></td>
 </tr>
 <tr>
 <td>Film well sticker</td>
 <td>GeneFluidics</td>
 <td></td>
 <td>Shipped with sensor chips</td>
 </tr>
 <tr>
 <td>Bare gold 16-sensor array chips </td>
 <td>GeneFluidics</td>
 <td>SC1000-16X-B </td>
 <td>Store in 100% N2 at room temperature</td>
 </tr>
 <tr>
 <td>Bovine Serum Albumin </td>
 <td>Sigma</td>
 <td>A7906 </td>
 <td>Store at 4 &deg;C</td>
 </tr>
 <tr>
 <td>1M Phosphate Buffer, pH 7.2 </td>
 <td></td>
 <td></td>
 <td>0.35M NaH2PO4, 0.65M K2HPO4, adjusted to pH 7.2</td>
 </tr>
 <tr>
 <td>Blocker Casein in PBS </td>
 <td>Pierce</td>
 <td>37528 </td>
 <td>Dilute with an equal volume of 1M Phosphate Buffer, pH 7.2, store at 4 &deg;C</td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Table 1. Reagents and Equipment.</td>
 </tr>
 </tbody>
</table>

bacterial detection &amp; identification using electrochemical sensors

Les capteurs électrochimiques sont largement utilisés pour la mesure rapide et précise de glucose dans le sang et peuvent être adaptés à la détection d&#39;une large variété d&#39;analytes. Les capteurs électrochimiques fonctionnent par transduction d&#39;un événement de reconnaissance biologique en un signal électrique utile. La transduction de signal se produit par couplage de l&#39;activité d&#39;une enzyme d&#39;oxydo-réduction pour une électrode ampérométrique. spécificité du capteur est soit une caractéristique inhérente de l&#39;enzyme, la glucose-oxydase dans le cas d&#39;un capteur de glucose, ou un produit de couplage entre l&#39;enzyme et un anticorps ou une sonde. Ici, nous décrivons une méthode de dosage du capteur électrochimique pour détecter directement et identifier les bactéries. Dans tous les cas, les sondes décrites ici sont des oligonucléotides d&#39;ADN. Cette méthode est basée sur hybridation sandwich de capture et de détection des sondes avec cible ARN ribosomal (ARNr). La sonde de capture est fixée à la surface du capteur, tandis que la sonde de détection est lié à horseradish peroxydase (HRP). Quand un substrat tel que le 3,3 &#39;, 5,5&#39;-tétraméthylbenzidine (TMB) est ajouté à une électrode avec des complexes de capture-cible-détecteur lié à sa surface, le substrat est oxydée par le HRP et réduit par l&#39;électrode de travail. Cette redox cycle conduit à la navette d&#39;électrons par le substrat de l&#39;électrode à la HRP, produisant le flux de courant dans l&#39;électrode.

Nous décrivons un dosage électrochimique qui est structuré de manière similaire à un test ELISA sandwich. Comme le montre la figure 1, la cible d&#39;ARN ribosomal (ARNr) l&#39;hybridation avec des sondes de capture et de détection est développée par une réaction d&#39;oxydo-réduction catalysée par HRP conjugué à des fragments d&#39;anticorps anti-fluorescéine qui se lient à la liaison 3 &#39;fluorescéine sur la sonde de détection. Un élément important de la sensibilité du dosage est...

Watch this Scientific Journal Video about Bacterial Detection & Identification Using Electrochemical Sensors at JoVE.com

Bacterial Detection &amp; Identification Using Electrochemical Sensors

Nous décrirons une méthode de dosage du capteur électrochimique pour la détection rapide de bactéries et d&#39;identification. L&#39;essai comporte une matrice de capteurs fonctionnalisé avec de l&#39;ADN d&#39;oligonucléotides sondes de capture pour des séquences spécifiques d&#39;espèces d&#39;ARN ribosomique (ARNr). Sandwich hybridation de l&#39;ARNr cible avec la sonde de capture et une sonde de détection d&#39;oligonucléotides d&#39;ADN lié à la peroxydase de raifort produit un courant ampérométrique mesurable.

Bacterial Detection &amp; identification au moyen de capteurs électrochimiques

Electrochemical  sensors are widely used for rapid and accurate measurement of blood glucose and  can be adapted for detection of a wide variety of ...

bacterial-detection-identification-using-electrochemical-sensors

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Bioengineering

28.1K vues.  Veterans Affairs Greater Los Angeles Healthcare System. Nous décrirons une méthode de dosage du capteur électrochimique pour la détection rapide de bactéries et d'identification. L'essai comporte une matrice de capteurs fonctionnalisé avec de l'ADN d'oligonucléotides sondes de capture pour des séquences spécifiques d'espèces d'ARN ribosomique (ARNr). Sandwich hybridation de l'ARNr cible avec la sonde de capture et une sonde de détection d'oligonucléotides d'ADN lié à la peroxyd...

Vidéo: Bacterial Detection & Identification Using Electrochemical Sensors

Characterizing Bacterial Volatiles using Secondary Electrospray Ionization Mass Spectrometry (SESI-MS)

Secondary electrospray ionization mass spectrometry (SESI-MS) is a method developed for the rapid detection of volatile compounds, without the need for sample pretreatment. The method was first described by Fenn and colleagues1 and has been applied to the detection of illicit drugs2 and explosives3-4, the characterization of skin volatiles5, and the analysis of breath6-7.
SESI ionization occurs by proton transfer reactions between the electrospray solution and the volatile analyte, and is therefore suitable for the analysis of hetero-organic molecules, just as in traditional electrospray ionization (ESI). However, unlike standard ESI, the proton transfer process of SESI occurs in the vapor phase rather than in solution (Fig. 1), and therefore SESI is best suited for detecting organic volatiles and aerosols.
We are expanding the use of SESI-MS to the detection of bacterial volatiles as a method for bacterial identification and characterization8. We have demonstrated that SESI-MS volatile fingerprinting, combined with a statistical analysis method, can be used to differentiate bacterial genera, species, and mixed cultures in a variety of growth media.8 Here we provide the steps for obtaining bacterial volatile fingerprints using SESI-MS, including the instrumental parameters that should be optimized to ensure robust bacterial identification and characterization.

Characterizing Bacterial Volatiles using Secondary Electrospray Ionization Mass Spectrometry SESI-MS

Secondary electrospray ionization mass spectrometry (SESI-MS) enables the detection of volatile organic compounds (VOCs) without the need for any sample pretreatment. This protocol provides instructions for the rapid (within minutes) characterization of bacterial VOCs using SESI-MS.

Caractériser Volatiles bactérienne secondaire à l&#39;aide d&#39;ionisation électrospray spectrométrie de masse (SESI-MS)

Secondary electrospray ionization mass spectrometry (SESI-MS) is a method developed for the rapid detection of volatile compounds, without the need for ...

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Bio-ingénierie

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 
receive the results. ...

Hollow Microneedle-based Sensor for Multiplexed Transdermal Electrochemical Sensing

The development of a minimally invasive multiplexed monitoring system for rapid analysis of biologically-relevant molecules could offer individuals suffering from chronic medical conditions facile assessment of their immediate physiological state. Furthermore, it could serve as a research tool for analysis of complex, multifactorial medical conditions. In order for such a multianalyte sensor to be realized, it must be minimally invasive, sampling of interstitial fluid must occur without pain or harm to the user, and analysis must be rapid as well as selective.
Initially developed for pain-free drug delivery, microneedles have been used to deliver vaccines and pharmacologic agents (e.g., insulin) through the skin.1-2 Since these devices access the interstitial space, microneedles that are integrated with microelectrodes can be used as transdermal electrochemical sensors. Selective detection of glucose, glutamate, lactate, hydrogen peroxide, and ascorbic acid has been demonstrated using integrated microneedle-electrode devices with carbon fibers, modified carbon pastes, and platinum-coated polymer microneedles serving as transducing elements.3-7,8
This microneedle sensor technology has enabled a novel and sophisticated analytical approach for in situ and simultaneous detection of multiple analytes. Multiplexing offers the possibility of monitoring complex microenvironments, which are otherwise difficult to characterize in a rapid and minimally invasive manner. For example, this technology could be utilized for simultaneous monitoring of extracellular levels of, glucose, lactate and pH,9 which are important metabolic indicators of disease states7,10-14 (e.g., cancer proliferation) and exercise-induced acidosis.15

This article details the construction of a multiplexed microneedle-based sensor. The device is being developed for in situ sampling and electrochemical analysis of multiple analytes in a rapid and selective manner. We envision clinical medicine and biomedical research uses for these microneedle-based sensors.

MICRO-creux à base de capteur pour multiplexée transdermique Sensing électrochimique

The development of a minimally invasive multiplexed monitoring system for rapid analysis of biologically-relevant molecules could offer individuals ...

Sensing of Barrier Tissue Disruption with an Organic Electrochemical Transistor

The gastrointestinal tract is an example of barrier tissue that provides a physical barrier against entry of pathogens and toxins, while allowing the passage of necessary ions and molecules. A breach in this barrier can be caused by a reduction in the extracellular calcium concentration. This reduction in calcium concentration causes a conformational change in proteins involved in the sealing of the barrier, leading to an increase of the paracellular flux. To mimic this effect the calcium chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N&#39;,N&#39;-tetra acetic acid (EGTA) was used on a monolayer of cells known to be representative of the gastrointestinal tract. Different methods to detect the disruption of the barrier tissue already exist, such as immunofluorescence and&#160;permeability assays. However, these methods are time-consuming and costly and not suited to dynamic or high-throughput measurements. Electronic methods for measuring barrier tissue integrity also exist for measurement of the transepithelial resistance (TER), however these are often costly and complex. The development of rapid, cheap, and sensitive methods is urgently needed as the integrity of barrier tissue is a key parameter in drug discovery and pathogen/toxin diagnostics. The organic electrochemical transistor (OECT) integrated with barrier tissue forming cells has been shown as a new device capable of dynamically monitoring barrier tissue integrity. The device is able to measure minute variations in ionic flux with unprecedented temporal resolution and sensitivity, in real time, as an indicator of barrier tissue integrity. This new method is based on a simple device that can be compatible with high throughput screening applications and fabricated at low cost.

The Organic Electrochemical Transistor is integrated with live cells and used to monitor ion flux across the gastrointestinal epithelial barrier. In this study, an increase in ion flux, related to disruption of tight junctions, induced by the presence of the calcium chelator EGTA (ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetra acetic acid), is measured.

Détection de perturbation des tissus barrière avec un transistor électrochimique organique

The gastrointestinal tract is an example of barrier tissue that provides a physical barrier against entry of pathogens and toxins, while allowing the ...

Glutamine Flux Imaging Using Genetically Encoded Sensors

Genetically encoded sensors allow real-time monitoring of biological molecules at a subcellular resolution. A tremendous variety of such sensors for biological molecules became available in the past 15 years, some of which became indispensable tools that are used routinely in many laboratories.
One of the exciting applications of genetically encoded sensors is the use of these sensors in investigating cellular transport processes. Properties of transporters such as kinetics and substrate specificities can be investigated at a cellular level, providing possibilities for cell-type specific analyses of transport activities. In this article, we will demonstrate how transporter dynamics can be observed using genetically encoded glutamine sensor as an example. Experimental design, technical details of the experimental settings, and considerations for post-experimental analyses will be discussed.

This article will demonstrate how to monitor glutamine dynamics in live cells using FRET. Genetically encoded sensors allow real-time monitoring of biological molecules at a subcellular resolution. Experimental design, technical details of the experimental settings, and considerations for post-experimental analyses will be discussed for genetically encoded glutamine sensors.

Glutamine Flux Imaging Utilisation de capteurs génétiquement codés

Genetically encoded sensors allow real-time monitoring of biological molecules at a subcellular resolution. A tremendous variety of such sensors for ...

A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis

Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration of pre-processing steps. Utilizing these devices towards the analysis of DNA hybridization events is important because it offers a technology for real time assessment of biomarkers at the point-of-care for various diseases. However, when the device footprint decreases the dominance of various physical phenomena increases. These phenomena influence the fabrication precision and operation reliability of the device. Therefore, there is a great need to accurately fabricate and operate these devices in a reproducible manner in order to improve the overall performance. Here, we describe the protocols and the methods used for the fabrication and the operation of a microfluidic-based electrochemical biochip for accurate analysis of DNA hybridization events. The biochip is composed of two parts: a microfluidic chip with three parallel micro-channels made of polydimethylsiloxane (PDMS), and a 3 x 3 arrayed electrochemical micro-chip. The DNA hybridization events are detected using electrochemical impedance spectroscopy (EIS) analysis. The EIS analysis enables monitoring variations of the properties of the electrochemical system that are dominant at these length scales. With the ability to monitor changes of both charge transfer and diffusional resistance with the biosensor, we demonstrate the selectivity to complementary ssDNA targets, a calculated detection limit of 3.8 nM, and a 13% cross-reactivity with other non-complementary ssDNA following 20 min&#160;of incubation. This methodology can improve the performance of miniaturized devices by elucidating on the behavior of diffusion at the micro-scale regime and by enabling the study of DNA hybridization events.

We present a microfluidic-based electrochemical biochip for DNA hybridization detection. Following ssDNA probe functionalization, the specificity, sensitivity, and detection limit are studied with complementary and non-complementary ssDNA targets. Results illustrate the influence of the DNA hybridization events on the electrochemical system, with a detection limit of 3.8 nM.

Une biopuce microfluidique électrochimique à base d&#39;analyse ADN hybridation Sans étiquette

Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration ...

Flying Insect Detection and Classification with Inexpensive Sensors

An inexpensive, noninvasive system that could accurately classify flying insects would have important implications for entomological research, and allow for the development of many useful applications in vector and pest control for both medical and agricultural entomology. Given this, the last sixty years have seen many research efforts devoted to this task. To date, however, none of this research has had a lasting impact. In this work, we show that pseudo-acoustic optical sensors can produce superior data; that additional features, both intrinsic and extrinsic to the insect&#8217;s flight behavior, can be exploited to improve insect classification; that a Bayesian classification approach allows to efficiently learn classification models that are very robust to over-fitting, and a general classification framework allows to easily incorporate arbitrary number of features. We demonstrate the findings with large-scale experiments that dwarf all previous works combined, as measured by the number of insects and the number of species considered.

We proposed a system that uses inexpensive, noninvasive pseudo-acoustic optical sensors to automatically and accurately detect, count, and classify flying insects based on their flying sound.

Insectes volants Détection et classification des capteurs peu coûteux

An inexpensive, noninvasive system that could accurately classify flying insects would have important implications for entomological research, and allow ...

Label-free Single Molecule Detection Using Microtoroid Optical Resonators

Detecting small concentrations of molecules down to the single molecule limit has impact on areas such as early detection of disease, and fundamental studies on the behavior of molecules. Single molecule detection techniques commonly utilize labels such as fluorescent tags or quantum dots, however, labels are not always available, increase cost and complexity, and can perturb the events being studied. Optical resonators have emerged as a promising means to detect single molecules without the use of labels. Currently the smallest particle detected by a non-plasmonically-enhanced bare optical resonator system in solution is a 25 nm polystyrene sphere1. We have developed a technique known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that can surpass this limit and achieve label-free single molecule detection in aqueous solution2. As signal strength scales with particle volume, our work represents a &#62; 100x improvement in the signal to noise ratio (SNR) over the current state of the art. Here the procedures behind FLOWER are presented in an effort to increase its usage in the field.

We have developed a label-free biosensing system based on optical resonator technology known as Frequency Locking Optical Whispering Evanescent Resonator (FLOWER) that is capable of detecting single molecules in solution. Here the procedures behind this work are described and presented.

Simple détection de molécule libre Label-Utilisation Microtoroid optiques résonateurs

Detecting small concentrations of molecules down to the single molecule limit has impact on areas such as early detection of disease, and fundamental ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

Multicolor détection Fluorescence pour Droplet microfluidique utilisant des fibres optiques

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...

Development of an Electrochemical DNA Biosensor to Detect a Foodborne Pathogen

Vibrio parahaemolyticus (V. parahaemolyticus) is a common foodborne pathogen that contributes to a large proportion of public health problems globally, significantly affecting the rate of human mortality and morbidity. Conventional methods for the detection of V. parahaemolyticus such as culture-based methods, immunological assays, and molecular-based methods require complicated sample handling and are time-consuming, tedious, and costly. Recently, biosensors have proven to be a promising and comprehensive detection method with the advantages of fast detection, cost-effectiveness, and practicality. This research focuses on developing a rapid method of detecting V. parahaemolyticus with high selectivity and sensitivity using the principles of DNA hybridization. In the work, characterization of synthesized polylactic acid-stabilized gold nanoparticles (PLA-AuNPs) was achieved using X-ray Diffraction (XRD), Ultraviolet-visible Spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM), Field-emission Scanning Electron Microscopy (FESEM), and Cyclic Voltammetry (CV). We also carried out further testing of stability, sensitivity, and reproducibility of the PLA-AuNPs. We found that the PLA-AuNPs formed a sound structure of stabilized nanoparticles in aqueous solution. We also observed that the sensitivity improved as a result of the smaller charge transfer resistance (Rct) value and an increase of active surface area (0.41 cm2). The development of our DNA biosensor was based on modification of a screen-printed carbon electrode (SPCE) with PLA-AuNPs and using methylene blue (MB) as the redox indicator. We assessed the immobilization and hybridization events by differential pulse voltammetry (DPV). We found that complementary, non-complementary, and mismatched oligonucleotides were specifically distinguished by the fabricated biosensor. It also showed reliably sensitive detection in cross-reactivity studies against various food-borne pathogens and in the identification of V. parahaemolyticus in fresh cockles.

A protocol for the development of an electrochemical DNA biosensor comprising a polylactic acid-stabilized, gold nanoparticles-modified, screen-printed carbon electrode to detect Vibrio parahaemolyticus is presented.

Développement d’un Biocapteur électrochimique ADN pour détecter un pathogène d’origine alimentaire

Vibrio parahaemolyticus (V. parahaemolyticus) is a common foodborne pathogen that contributes to a large proportion of public health problems globally, ...