Ce travail a été soutenu par la Fondation sciences Israël (subvention n ° 1118-1108 et n ° subvention 1146-1112) et le Fonds de recherche Memorial Kroll Minna. ES reconnaît avec gratitude le soutien financier de la Berrie Nanotechnology Institute Russell.

Une. Préparation du oxydé poreux SiO 2 <ol><li> Plaquettes Etch Si (un seul côté brillant sur la &lt;100&gt; visage et fortement dopée, de type p, 0,0008 Ω · cm) dans une solution 3:1 (v / v) de solution aqueuse de HF et d&#39;éthanol absolu pendant 30 secondes à un courant constant densité de 385 mA / cm 2. S&#39;il vous plaît noter que HF est un liquide très corrosif, et il doit être manipulé avec un soin extrême. </li><li> Rincer la surface du Si poreux (PSi) film résultant avec de l&#39;éthanol absolu à plusieurs reprises; sécher les films sous un gaz d&#39;azote sec. </li><li> Oxyder les échantillons PSi fraîchement gravé dans un four tubulaire à 800 ° C pendant 1 h dans l&#39;air ambiant (placer l&#39;échantillon dans le four à la température ambiante, chauffer le four à 800 ° C, laisser dans le four pendant 1 heure, éteignez le la chaudière et retirer les échantillons du four seulement à la température ambiante). </li></ol> 2. Biofonctionnalisation de Psio 2 échafaudages <ol><li> Incuber un PSi oxydé (PSIO 2) l&#39;échantillon pendant 1 heure dans mercaptopropyl (95% (MPTS) solution de triméthoxysilane-3) (108 mM dans du toluène). </li><li> Rincer le Psio 2 échantillon traité au silane avec du toluène, le méthanol et l&#39;acétone; sec sous un gaz d&#39;azote sec. </li><li> Incuber la Psio 2 échantillon de silane modifié pendant 30 min dans 1 ml de solution 100 mM PEO-iodoacétyle biotine. </li><li> Rincer le Psio 2 Extrait biotine traités avec 0,1 M de tampon phosphate salin (PBS) de solution à plusieurs reprises. </li><li> Incuber l&#39;échantillon 2 Psio biotine modifiée pendant 30 min dans 1 ml de pg / ml de streptavidine (SA) solution 100. </li><li> Rincer le SA-traité Psio 2 échantillon avec une solution 0,1 M PBS plusieurs fois. </li><li> Incuber l&#39;échantillon SA-modifié Psio 2 résultant pendant 30 min dans 1 ml de 100 pg / ml biotinylé E. Anticorps monoclonal coli (immunoglobuline G, IgG) ou avec une solution de 100 ug / ml d&#39;IgG de lapin biotinylé (comme un modèle pour un anticorps monoclonal). </li></ol> 3. Marquage fluorescent et microscopie de fluorescence <ol><li> Incuber les surfaces IgG modifiés avec 15 ug / ml de fluorescéine (FITC) marqué d&#39;anti IgG de lapin pendant 40 min et à 15 ug / ml de fluorescéine (FITC) marqué IgG anti-souris comme témoin. </li><li> Rincer les échantillons modifiés avec 0,1 M de solution PBS à plusieurs reprises. </li><li> Examiner les échantillons sous un microscope à fluorescence. </li></ol> 4. Culture de bactéries <ol><li> Cultiver E. bactéries coli K12 dans un tube de 10 ml avec 5 ml de milieu Luria Bertani (LB) (moyenne composition dans 1 litre d&#39;eau désionisée: 5 g de NaCl, 5 g d&#39;extrait de levure et 10 g de tryptone). Incuber les bactéries secouant la nuit à 37 ° C. </li><li> Surveiller la concentration des bactéries par la lecture de la densité optique (DO) à une longueur d&#39;onde de 600 nm. Après croissance pendant une nuit dans du milieu LB, lire la DO600 en utilisant un spectrophotomètre pour déterminer la concentration bactérienne. Le nombre de cellules est désastreusecte proportionnelles aux mesures (OD 600 DO 600 = 1 10 8 cellules / ml). </li></ol> 5. Les bactéries de détection <ol><li> Placez le Psio IgG-2 modifié et soigné Psio 2 (comme le contrôle) des échantillons dans une cellule d&#39;écoulement en plexiglas sur mesure. Fixer la cellule d&#39;écoulement pour s&#39;assurer que l&#39;échantillon réflectivité est mesurée au même endroit au cours de toutes les mesures. </li><li> Incuber les échantillons avec E. coli K12 suspension (10 4 cellules / ml) pendant 30 min à température ambiante. Ensuite, retirer la suspension de bactéries par rinçage de la cellule avec 0,85% p / solution saline v pendant 30 min. </li><li> Surveiller les changements dans les données de réflectivité dans l&#39;ensemble de l&#39;expérience. Toutes les mesures optiques doivent être effectués dans un milieu aqueux environnant. Spectra devrait être recueilli en utilisant un spectromètre CCD et analysée par application d&#39;une transformée de Fourier rapide (FFT), comme décrit précédemment 25,26. </li><li> Confirmer la présence de la bactérie sur lasurface du biocapteur, par l&#39;observation des échantillons sous un microscope optique verticale immédiatement après l&#39;expérience de biocapteurs. </li></ol>

<ol>
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Les auteurs déclarent aucun intérêt financier concurrents.

Un immunocapteur optique sans étiquette, sur la base d&#39;un Psio 2 nanostructure (un film mince de Fabry-Pérot) est fabriqué, et son application potentielle comme un biocapteur pour la détection de bactéries est confirmée. Modifications et dépannage L&#39;une des préoccupations majeures lors de la conception d&#39;un immunocapteur est la sensibilité des anticorps à subir des changements de conformation non souhaitées pendant le dépôt et la ...

Précoce et précise l&#39;identification des bactéries pathogènes est extrêmement important pour la sécurité alimentaire et de l&#39;eau, surveillance de l&#39;environnement, et le point-of-care diagnostic 1. Les techniques traditionnelles de microbiologie sont longues, laborieuses, et n&#39;ont pas la capacité de détecter des micro-organismes en &quot;temps réel&quot; ou à l&#39;extérieur de l&#39;environnement de laboratoire, les biocapteurs évoluent pour répondre à ces défis 2-5. Au cours des dernières années, le Si poreux (PSI) a émergé comme une plate-forme prometteuse pour la conception de capteurs et biocapteurs 6-20. Cours de la dernière décennie, de nombreuses études concernant les capteurs et biocapteurs optiques à base de PSI-ont été publiés 21,22. La couche nanostructurée PSi est typiquement fabriqué par gravure électrochimique anodique à partir d&#39;un monocristal de Si plaquette. Les nanomatériaux PSi obtenus présentent de nombreuses caractéristiques avantageuses, comme une grande surface et le volume libre, tailles de pores qui peuvent être contrôlés et accordable optipropriétés cal 10,16. Les propriétés optiques de la couche de PSi, comme photoluminescence 8,11 et lumière blanche interférométrie à base de réflectance 7,19, sont fortement influencées par les conditions environnementales. Capture d&#39;analytes voyageurs molécules / cible à l&#39;intérieur des résultats de couches poreuses à une variation de l&#39;indice de réfraction moyen de la pellicule, comme une modulation observée dans le spectre de photoluminescence ou sous forme de décalage de longueur d&#39;onde dans le spectre de réflectivité 10. Bien que la grande innovation dans la technologie des biocapteurs optiques PSi, il n&#39;y a que peu de rapports sur les plates-formes à base de PSI-pour la détection de bactéries 6,8,20,23-29. En outre, la plupart de ces études de preuve de concept ont démontré «indirecte» de détection des bactéries. Ainsi, en général, avant la lyse des cellules est nécessaire pour extraire les fragments de protéine / ADN ciblés, caractéristiques de la bactérie étudiée 29. Notre approche consiste à saisir directement les bactéries ciblescellules sur le biocapteur psi. Par conséquent, les anticorps monoclonaux, qui sont spécifiques à une cible, les bactéries, sont immobilisés sur la surface poreuse. La liaison de cellules de bactéries, par l&#39;intermédiaire d&#39;interactions anticorps-antigène, à la surface du biocapteur induire des changements dans l&#39;amplitude (intensité) du spectre de réflectivité de 24 à 26. Dans ce travail, nous rapportons sur la construction d&#39;un biocapteur à base de PSI-optique et de démontrer son application comme les biocapteurs plate-forme sans étiquette pour la détection d&#39;Escherichia coli (E. coli) K12 (utilisées comme un micro-organisme modèle). L&#39;surveillés le signal optique est de la lumière réfléchie à partir de la nanostructure PSi raison de Fabry-Pérot mince film interférence (Figure 1A). Les variations de l&#39;amplitude / intensité de la lumière sont corrélés à l&#39;immobilisation spécifique des cellules des bactéries cibles sur la surface du biocapteur, permettant une détection rapide et une quantification des bactéries.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Si wafer</td>
			<td>Siltronix Corp.</td>
			<td></td>
			<td>Highly-B-doped, p-type, 0.0008 &#937;-cm resistivity, &#60;100&#62; oriented</td>
		</tr>
		<tr>
			<td>Aqueous HF (48%)</td>
			<td>Merck</td>
			<td>101513</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol absolute</td>
			<td>Merck</td>
			<td>818760</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS buffer solution (pH 7.4)</td>
			<td></td>
			<td></td>
			<td>prepared by dissolving 50 mM Na2HPO4, 17 mM NaH2PO4, and 68 mM NaCl in Milli-Q water (18.2 M&#937;)</td>
		</tr>
		<tr>
			<td>Saline 0.85% w/v</td>
			<td></td>
			<td></td>
			<td>prepared by dissolving 0.85 g NaCl in 100 ml Milli-Q water (18.2 M&#937;)</td>
		</tr>
		<tr>
			<td>95% (3-Mercaptopropyl)trimethoxysilane (MPTS)</td>
			<td>Sigma Aldrich Chemicals</td>
			<td>175617</td>
			<td></td>
		</tr>
		<tr>
			<td>PEO-iodoacetyl biotin</td>
			<td>Sigma Aldrich Chemicals</td>
			<td>B2059</td>
			<td></td>
		</tr>
		<tr>
			<td>Streptavidin (SA)</td>
			<td>Jackson ImmunoResearch Labs Inc.</td>
			<td>016-000-114</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescein (DTAF)-streptavidin</td>
			<td>Jackson ImmunoResearch Labs Inc.</td>
			<td>016-010-084</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated-rabbit IgG</td>
			<td>Jackson ImmunoResearch Labs Inc.</td>
			<td>011-060-003</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescently tagged anti-rabbit IgG</td>
			<td>Jackson ImmunoResearch Labs Inc.</td>
			<td>111-095-003</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescently tagged anti-mouse IgG</td>
			<td>Jackson ImmunoResearch Labs Inc.</td>
			<td>115-095-003</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated E. coli antibody</td>
			<td>Jackson ImmunoResearch Labs Inc.</td>
			<td>1007</td>
			<td></td>
		</tr>
		<tr>
			<td>E. coli (K-12)</td>
			<td></td>
			<td></td>
			<td>was generously supplied by Prof. Sima Yaron, Technion</td>
		</tr>
	</tbody>
</table>

optical detection of e. coli bacteria by mesoporous silicon biosensors

<html> Un biocapteur optique sans étiquette basée sur une nanostructure poreuse de Si est conçu pour la saisie rapide et la détection de bactéries Escherichia coli K12, comme un micro-organisme du modèle. Le biocapteur repose sur la liaison directe des cellules des bactéries cibles sur sa surface, tandis qu&#39;aucun traitement préalable (par exemple par lyse cellulaire) de l&#39;échantillon étudié est nécessaire. Un film mince de Si mésoporeux est utilisé comme élément de capteur optique du biocapteur. Sous éclairage en lumière blanche, la couche poreuse affiche motifs de franges de Fabry-Pérot bien résolus dans le spectre de réflectivité. En appliquant une transformée de Fourier rapide (FFT) pour les résultats des données de réflectivité dans un seul pic. Les variations de l&#39;intensité du pic FFT sont surveillés. Ainsi, les bactéries cibles capturer sur la surface du biocapteur, par des interactions anticorps-antigène, induit des changements mesurables dans l&#39;intensité des pics de la FFT, permettant une observation «en temps réel» de l&#39;attachement de bactéries. nt &quot;&gt; Le film de Si mésoporeux, fabriqué par un procédé d&#39;anodisation électrochimique, est conjugué avec des anticorps monoclonaux, spécifiques de la bactérie cible. L&#39;immobilisation, immunoactivité et la spécificité des anticorps sont confirmées par des expériences de marquage par fluorescence. Une fois que le capteur biologique est exposée à l&#39; bactéries cibles, les cellules sont directement capturés sur la surface de Si poreux anticorps modifié. Ces événements de capture spécifiques entraînent des changements d&#39;intensité dans le film mince spectre du biocapteur optique interférentiel. Nous démontrons que ces biocapteurs peuvent détecter des concentrations relativement faibles de bactéries (détection limite de 10 4 cellules / ml) en moins d&#39;une heure.

PSi oxydée (2) Psio films sont préparés comme décrit dans la section du texte protocole. Figure 1B montre une micrographie électronique à balayage à haute résolution de la pellicule de PSi obtenu après oxydation thermique. La couche Psio 2 est caractérisé par des pores cylindriques bien définis ayant un diamètre dans la gamme de 30 à 80 nm. L&#39;anticorps monoclonal (IgG) molécules sont greffées sur les Psio deux surfaces à ...

Watch this Scientific Journal Video about Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors at JoVE.com

Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors

Un biocapteur optique sans étiquette pour la détection de bactéries rapides est introduit. Le biocapteur est basé sur un silicium poreux nanostructuré, qui est conçu pour capter directement les cellules des bactéries cibles sur sa surface. Nous utilisons des anticorps monoclonaux, immobilisés sur le transducteur poreux, comme les sondes de capture. Nos études démontrent l&#39;applicabilité de ces biocapteurs pour la détection de concentrations bactériennes faibles en quelques minutes sans traitement préalable de l&#39;échantillon (telle que la lyse cellulaire).

Détection optique de<em&gt; E. coli</em&gt; Bactérie par mésoporeux Silicon biocapteurs

A label-free optical biosensor based on a nanostructured porous Si is designed for rapid capture and detection of Escherichia coli K12 bacteria, as a ...

optical-detection-of-e-coli-bacteria-by-mesoporous-silicon-biosensors

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Bioengineering

Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors

16.8K vues.  Technion - Israel Institute of Technology.  Un biocapteur optique sans étiquette pour la détection de bactéries rapides est introduit. Le biocapteur est basé sur un silicium poreux nanostructuré, qui est conçu pour capter directement les cellules des bactéries cibles sur sa surface. Nous utilisons des anticorps monoclonaux, immobilisés sur le transducteur poreux, comme les sondes de capture. Nos études démontrent l'applicabilité de ces biocapteurs pour la détection de concentrations bactériennes f...

Vidéo: Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors

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. ...

Recherche

Bio-ingénierie

A Cre-Lox P Recombination Approach for the Detection of Cell Fusion In Vivo

The ability of two or more cells of the same type to fuse has been utilized in metazoans throughout evolution to form many complex organs, including skeletal muscle, bone and placenta. Contemporary studies demonstrate fusion of cells of the same type confers enhanced function. For example, when the trophoblast cells of the placenta fuse to form the syncytiotrophoblast, the syncytiotrophoblast is better able to transport nutrients and hormones across the maternal-fetal barrier than unfused trophoblasts1-4. More recent studies demonstrate fusion of cells of different types can direct cell fate. The "reversion" or modification of cell fate by fusion was once thought to be limited to cell culture systems. But the advent of stem cell transplantation led to the discovery by us and others that stem cells can fuse with somatic cells in vivo and that fusion facilitates stem cell differentiation5-7. Thus, cell fusion is a regulated process capable of promoting cell survival and differentiation and thus could be of central importance for development, repair of tissues and even the pathogenesis of disease.
Limiting the study of cell fusion, is lack of appropriate technology to 1) accurately identify fusion products and to 2) track fusion products over time. Here we present a novel approach to address both limitations via induction of bioluminescence upon fusion (Figure 1); bioluminescence can be detected with high sensitivity in vivo8-15. We utilize a construct encoding the firefly luciferase (Photinus pyralis) gene placed adjacent to a stop codon flanked by LoxP sequences. When cells expressing this gene fuse with cells expressing the Cre recombinase protein, the LoxP sites are cleaved and the stop signal is excised allowing transcription of luciferase. Because the signal is inducible, the incidence of false-positive signals is very low. Unlike existing methods which utilize the Cre/LoxP system16, 17, we have incorporated a "living" detection signal and thereby afford for the first time the opportunity to track the kinetics of cell fusion in vivo.
To demonstrate the approach, mice ubiquitously expressing Cre recombinase served as recipients of stem cells transfected with a construct to express luciferase downstream of a floxed stop codon. Stem cells were transplanted via intramyocardial injection and after transplantation intravital image analysis was conducted to track the presence of fusion products in the heart and surrounding tissues over time. This approach could be adapted to analyze cell fusion in any tissue type at any stage of development, disease or adult tissue repair.

A Cre-Lox P Recombination Approach for the Detection of Cell Fusion In Vivo

A method to track cell fusion in living organisms over time is described. The approach utilizes Cre-LoxP recombination to induce luciferase expression upon cell fusion. The luminescent signal generated can be detected in living organisms using biophotonic imaging systems with a sensitivity of detection of &tilde;1,000 cells in peripheral tissues.

Une approche recombinaison Cre-Lox P pour la détection de la fusion cellulaire In Vivo</em

The ability of two or more cells of the same type to fuse has been utilized in metazoans throughout evolution to form many complex organs, including ...

Attaching Biological Probes to Silica Optical Biosensors Using Silane Coupling Agents

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) technique), make use of various surface modification techniques, that can, for example, prevent surface fouling, tune the hydrophobicity / hydrophilicity of the surface, adapt to a variety of electronic environments, and most frequently, induce specificity towards a target of interest.1-5 These techniques extend the functionality of otherwise highly sensitive biosensors to real-world applications in complex environments, such as blood, urine, and wastewater analysis.2,6-7 While commercial biosensing platforms, such as Biacore, have well-understood, standard techniques for performing such surface modifications, these techniques have not been translated in a standardized fashion to other label-free biosensing platforms, such as Whispering Gallery Mode (WGM) optical resonators.8-9
WGM optical resonators represent a promising technology for performing label-free detection of a wide variety of species at ultra-low concentrations.6,10-12 The high sensitivity of these platforms is a result of their unique geometric optics: WGM optical resonators confine circulating light at specific, integral resonance frequencies.13 Like the SPR platforms, the optical field is not totally confined to the sensor device, but evanesces; this "evanescent tail" can then interact with species in the surrounding environment. This interaction causes the effective refractive index of the optical field to change, resulting in a slight, but detectable, shift in the resonance frequency of the device. Because the optical field circulates, it can interact many times with the environment, resulting in an inherent amplification of the signal, and very high sensitivities to minor changes in the environment.2,14-15
To perform targeted detection in complex environments, these platforms must be paired with a probe molecule (usually one half of a binding pair, e.g. antibodies / antigens) through surface modification.2 Although WGM optical resonators can be fabricated in several geometries from a variety of material systems, the silica microsphere is the most common. These microspheres are generally fabricated on the end of an optical fiber, which provides a "stem" by which the microspheres can be handled during functionalization and detection experiments. Silica surface chemistries may be applied to attach probe molecules to their surfaces; however, traditional techniques generated for planar substrates are often not adequate for these three-dimensional structures, as any changes to the surface of the microspheres (dust, contamination, surface defects, and uneven coatings) can have severe, negative consequences on their detection capabilities. Here, we demonstrate a facile approach for the surface functionalization of silica microsphere WGM optical resonators using silane coupling agents to bridge the inorganic surface and the biological environment, by attaching biotin to the silica surface.8,16 Although we use silica microsphere WGM resonators as the sensor system in this report, the protocols are general and can be used to functionalize the surface of any silica device with biotin.

Biosensors interface with complex, biological environments and perform targeted detection by combining highly sensitive sensors with highly specific probes attached to the sensor via surface modification. Here, we demonstrate the surface functionalization of silica optical sensors with biotin using silane coupling agents to bridge the sensor and the biological environment.

Fixation des sondes biologiques à des biocapteurs optiques de silice à l&#39;aide d&#39;agents de couplage au silane

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) ...

Analyzing Cellular Internalization of Nanoparticles and Bacteria by Multi-spectral Imaging Flow Cytometry

Nanoparticulate systems have emerged as valuable tools in vaccine delivery through their ability to efficiently deliver cargo, including proteins, to antigen presenting cells1-5. Internalization of nanoparticles (NP) by antigen presenting cells is a critical step in generating an effective immune response to the encapsulated antigen. To determine how changes in nanoparticle formulation impact function, we sought to develop a high throughput, quantitative experimental protocol that was compatible with detecting internalized nanoparticles as well as bacteria. To date, two independent techniques, microscopy and flow cytometry, have been the methods used to study the phagocytosis of nanoparticles. The high throughput nature of flow cytometry generates robust statistical data. However, due to low resolution, it fails to accurately quantify internalized versus cell bound nanoparticles. Microscopy generates images with high spatial resolution; however, it is time consuming and involves small sample sizes6-8. Multi-spectral imaging flow cytometry (MIFC) is a new technology that incorporates aspects of both microscopy and flow cytometry that performs multi-color spectral fluorescence and bright field imaging simultaneously through a laminar core. This capability provides an accurate analysis of fluorescent signal intensities and spatial relationships between different structures and cellular features at high speed.
	Herein, we describe a method utilizing MIFC to characterize the cell populations that have internalized polyanhydride nanoparticles or Salmonella enterica serovar Typhimurium. We also describe the preparation of nanoparticle suspensions, cell labeling, acquisition on an ImageStreamX system and analysis of the data using the IDEAS application. We also demonstrate the application of a technique that can be used to differentiate the internalization pathways for nanoparticles and bacteria by using cytochalasin-D as an inhibitor of actin-mediated phagocytosis.

In this article, we describe a method utilizing multi-spectral imaging flow cytometry to quantify the internalization of polyanhydride nanoparticles or bacteria by RAW 264.7 cells.

Analyser l&#39;internalisation cellulaire de nanoparticules et de bactéries multi-spectrale par cytométrie de flux d&#39;imagerie

Nanoparticulate  systems have emerged as valuable tools in vaccine delivery through their  ability to efficiently deliver cargo, including proteins, to ...

Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria

A structurally transformed lytic bacteriophage having a broad host range of Staphylococcus aureus strains and a penicillin-binding protein (PBP 2a) antibody conjugated latex beads have been utilized to create a biosensor designed for discrimination of methicillin resistant (MRSA) and sensitive (MSSA) S. aureus species 1,2. The lytic phages have been converted into phage spheroids by contact with water-chloroform interface. Phage spheroid monolayers have been moved onto a biosensor surface by Langmuir-Blodgett (LB) technique 3. The created biosensors have been examined by a quartz crystal microbalance with dissipation tracking (QCM-D) to evaluate bacteria-phage interactions. Bacteria-spheroid interactions led to reduced resonance frequency and a rise in dissipation energy for both MRSA and MSSA strains. After the bacterial binding, these sensors have been further exposed to the penicillin-binding protein antibody latex beads. Sensors analyzed with MRSA responded to PBP 2a antibody beads; although sensors inspected with MSSA gave no response. This experimental distinction determines an unambiguous discrimination between methicillin resistant and sensitive S. aureus strains. Equally bound and unbound bacteriophages suppress bacterial growth on surfaces and in water suspensions. Once lytic phages are changed into spheroids, they retain their strong lytic activity and show high bacterial capture capability. The phage and phage spheroids can be utilized for testing and sterilization of antibiotic resistant microorganisms. Other applications may include use in bacteriophage therapy and antimicrobial surfaces.

Lytic phage biosensors and antibody beads are able to discriminate between methicillin resistant (MRSA) and sensitive staphylococcus bacteria. The phages were immobilized by a Langmuir-Blodgett method onto a surface of a quartz crystal microbalance sensor and worked as broad range staphylococcus probes. Antibody beads recognize MRSA.

Biocapteurs pour la détection de bactéries aux antibiotiques de staphylocoques résistants

A structurally transformed lytic bacteriophage having a broad host range of Staphylococcus aureus strains and a penicillin-binding protein (PBP 2a) ...

Use of Label-free Optical Biosensors to Detect Modulation of Potassium Channels by G-protein Coupled Receptors

Ion channels control the electrical properties of neurons and other excitable cell types by selectively allowing ions to flow through the plasma membrane1. To regulate neuronal excitability, the biophysical properties of ion channels are modified by signaling proteins and molecules, which often bind to the channels themselves to form a heteromeric channel complex2,3. Traditional assays examining the interaction between channels and regulatory proteins require exogenous labels that can potentially alter the protein&#39;s behavior and decrease the physiological relevance of the target, while providing little information on the time course of interactions in living cells. Optical biosensors, such as the X-BODY Biosciences BIND Scanner system, use a novel label-free technology, resonance wavelength grating (RWG) optical biosensors, to detect changes in resonant reflected light near the biosensor. This assay allows the detection of the relative change in mass within the bottom portion of living cells adherent to the biosensor surface resulting from ligand induced changes in cell adhesion and spreading, toxicity, proliferation, and changes in protein-protein interactions near the plasma membrane. RWG optical biosensors have been used to detect changes in mass near the plasma membrane of cells following activation of G protein-coupled receptors (GPCRs), receptor tyrosine kinases, and other cell surface receptors. Ligand-induced changes in ion channel-protein interactions can also be studied using this assay. In this paper, we will describe the experimental procedure used to detect the modulation of Slack-B sodium-activated potassium (KNa) channels by GPCRs.

Optical biosensor techniques can detect changes in mass near the plasma membrane in living cells and allow one to follow cellular responses in both individual cells and populations of cells. This protocol will describe detection of the modulation of potassium channels by G-protein coupled receptors in intact cells using this approach.

L&#39;utilisation de biocapteurs optiques sans étiquette pour détecter la modulation de potassium par les canaux G récepteurs couplés aux protéines

Ion channels control the electrical properties of neurons and other excitable cell types by selectively allowing ions to flow through the plasma ...

Nanomanipulation of Single RNA Molecules by Optical Tweezers

A large portion of the human genome is transcribed but not translated. In this post genomic era, regulatory functions of RNA have been shown to be increasingly important. As RNA function often depends on its ability to adopt alternative structures, it is difficult to predict RNA three-dimensional structures directly from sequence. Single-molecule approaches show potentials to solve the problem of RNA structural polymorphism by monitoring molecular structures one molecule at a time. This work presents a method to precisely manipulate the folding and structure of single RNA molecules using optical tweezers. First, methods to synthesize molecules suitable for single-molecule mechanical work are described. Next, various calibration procedures to ensure the proper operations of the optical tweezers are discussed. Next, various experiments are explained. To demonstrate the utility of the technique, results of mechanically unfolding RNA hairpins and a single RNA kissing complex are used as evidence. In these examples, the nanomanipulation technique was used to study folding of each structural domain, including secondary and tertiary, independently. Lastly, the limitations and future applications of the method are discussed.

Optical tweezers have been used to study RNA folding by stretching individual molecules from their 5&#8217; and 3&#8217; ends. Here common procedures are described to synthesize RNA molecules for tweezing, calibration of the instrument, and methods to manipulate single molecules.

Nanomanipulation de molécules d&#39;ARN simple par pinces optiques

A large portion of the human genome is transcribed but not translated. In this post genomic era, regulatory functions of RNA have been shown to be ...

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 ...

Synthesis of Infectious Bacteriophages in an E. coli-based Cell-free Expression System

A new generation of cell-free transcription-translation (TXTL) systems, engineered to have a greater versatility and modularity, provide novel capabilities to perform basic and applied sciences in test tube reactions. Over the past decade, cell-free TXTL has become a powerful technique for a broad range of novel multidisciplinary research areas related to quantitative and synthetic biology. The new TXTL platforms are particularly useful to construct and interrogate biochemical systems through the execution of synthetic or natural gene circuits. In vitro TXTL has proven convenient to rapidly prototype regulatory elements and biological networks as well as to recapitulate molecular self-assembly mechanisms found in living systems. In this article, we describe how infectious bacteriophages, such as MS2 (RNA), &#934;&#935;174 (ssDNA), and T7 (dsDNA), are entirely synthesized from their genome in one-pot reactions using an all Escherichia coli, cell-free TXTL system. Synthesis of the three coliphages is quantified using the plaque assay. We show how the yield of synthesized phage depends on the biochemical settings of the reactions. Molecular crowding, emulated through a controlled concentration of PEG 8000, affects the amount of synthesized phages by orders of magnitudes. We also describe how to amplify the phages and how to purify their genomes. The set of protocols and results presented in this work should be of interest to multidisciplinary researchers involved in cell-free synthetic biology and bioengineering.

Synthesis of Infectious Bacteriophages in an E. coli-based Cell-free Expression System

A new generation of cell-free transcription-translation platforms has been engineered to construct biochemical systems in vitro through the execution of gene circuits. In this article, we describe how bacteriophages, such as MS2, &#934;&#935;174, and T7, are synthesized from their genome using an all E. coli cell-free TXTL system.