Name: monitoring protein adsorption with solid-state nanopores
Uploaded: 2011-12-02T13:00:00
Description: Watch this Scientific Journal Video about Monitoring Protein Adsorption with Solid-state Nanopores at JoVE.com

Les auteurs tiennent à remercier John Grazul (Cornell University), André Marziali (L&#39;Université de la Colombie-Britannique à Vancouver) et Vincent Tabard-Cossa (L&#39;Université d&#39;Ottawa) pour leurs conseils. Ce travail est financé en partie par des subventions de la National Science Foundation américaine (DMR-0706517 et DMR-1006332) et le National Institutes of Health (R01-GM088403). Le forage a été effectué nanopore à l&#39;installation de microscopie électronique du Centre de Cornell pour la recherche sur les matériaux (CCMR) avec le soutien de la National Science Foundation - la recherche en sciences des matériaux et centres d&#39;ingénierie (MRSEC) programme (DMR 0520404). La préparation des membranes de nitrure de silicium a été réalisée à la Cornell facilité l&#39;échelle nanométrique, un membre du Réseau National Nanotechnology Infrastructure, qui est soutenu par la National Science Foundation (Grant ECS-0335765).

1. Fabrication de semi-conducteurs nanopores dans des membranes de nitrure de silicium <ol><li> Apportez de la FEI Tecnai F20 S / TEM à une tension d&#39;accélération de 200 kV. Si vous utilisez un autre S / TEM, la tension d&#39;accélération doit être supérieure ou égale à 200 kV 9 </li><li> Chargez une 20 nm d&#39;épaisseur de silicium de grille SPI fenêtre de nitrure dans le porte-échantillon TEM et nettoyer avec un plasma d&#39;oxygène pendant 30 secondes pour éliminer tous les contaminant...

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Spontanée adsorption des protéines sur des surfaces semi-conducteurs de 27 à 29 est fondamentalement important dans un certain nombre de domaines, tels que les applications de biopuces et la conception d&#39;une nouvelle classe de biomatériaux hybrides fonctionnels. Des études antérieures ont montré que les protéines adsorbées sur des surfaces semi-conducteurs ne montrent pas la mobilité latérale ou les taux de désorption significative, et donc l&#39;adsorption des protéines est généralement co...

<table border="1"><tr><td> Nom du réactif </td><td> Société </td><td> Numéro de catalogue </td><td> Commentaires </td></tr><tr><td> Tecnai F20 S / TEM </td><td> FEI </td><td></td><td> S / TEM nécessite source de tension d&#39;accélération ≥ 200kV et à émission de champ. </td></tr><tr><td> 20 nm d&#39;épaisseur fenêtre de membrane de nitrure de silicium pour le TEM </td><td> SPI </td><td> 4163SN-BA </td><td></td></tr><tr><td> Axon Axopatch 200B amplificateur de patch-clamp </td><td> Molecular Devices </td><td></td><td></td></tr><tr><td> Axon Digidata 1440A </td><td> Molecular Devices </td><td></td><td></td></tr><tr><td> pClamp 10 logiciels </td><td> Molecular Devices </td><td></td><td> Électrophysiologie Acquisition de données et d&#39;analyse du logiciel </td></tr><tr><td> L&#39;acide sulfurique </td><td> FIsher scientifique </td><td> A300 </td><td></td></tr><tr><td> peroxyde d&#39;hydrogène </td><td> Fisher Scientific </td><td> H325 </td><td></td></tr><tr><td> toriques en silicone </td><td> McMaster-Carr </td><td> 003 S70 </td><td> Sinon, utiliser le PDMS </td></tr><tr><td> fil d&#39;argent </td><td> Sigma-Aldrich </td><td> 348759 </td><td> Pour les électrodes </td></tr><tr><td> CPS technologie, D sous contact, broches </td><td> Newark </td><td> 9K4978 </td><td> Pour les électrodes </td></tr><tr><td> chlorure de potassium </td><td> Sigma </td><td> P9541 </td><td></td></tr><tr><td> phosphate de potassium dibasique </td><td> Sigma </td><td> P2222 </td><td></td></tr><tr><td> phosphate de potassium monobasique </td><td> Sigma </td><td> P5379 </td><td></td></tr><tr><td> PDMS </td><td> Dow Corning </td><td></td><td> Sylgar 184 Elastomer ensemble. Pour faire la chambre. </td></tr><tr><td> Kwik-Cast Mastic </td><td> Instruments de précision du monde </td><td> KWIK-CAST </td><td> Rapide mastic silicone agissant </td></tr><tr><td> plaque chauffante </td><td> Fisher Scientific </td><td></td><td></td></tr><tr><td> Cage de Faraday </td><td></td><td></td><td></td></tr></table>

monitoring protein adsorption with solid-state nanopores

Solid-state nanopores ont été utilisés pour effectuer des mesures au niveau molécule unique d&#39;examiner la structure locale et la flexibilité des acides nucléiques 1-6, le déroulement des protéines 7, et l&#39;affinité de liaison des ligands différents 8. En couplant ces nanopores à la technique résistive impulsion 9-12, de telles mesures peut être faite sous une grande variété de conditions et sans la nécessité d&#39;un étiquetage 3. Dans la technique résistive impulsions, une solution de sel ionique est introduite des deux côtés de la nanopore. Par conséquent, les ions sont entraînés par un côté de la chambre à l&#39;autre par un potentiel transmembranaire appliquée, résultant en un courant stable. Le partitionnement d&#39;un analyte dans le nanopore provoque une déviation bien définie dans ce courant, qui peuvent être analysés pour en extraire une seule molécule d&#39;informations. En utilisant cette technique, l&#39;adsorption de certaines protéines sur les parois nanopore peut être contrôlé dans une large gamme deconditions 13. L&#39;adsorption des protéines gagne en importance, parce que les dispositifs microfluidiques diminuer en taille, l&#39;interaction de ces systèmes avec des protéines unique devient une préoccupation. Ce protocole décrit un test rapide pour la protéine de liaison à des films de nitrure, qui peut être facilement étendu à d&#39;autres films minces se prêtent au forage nanopore, ou sur des surfaces de nitrure fonctionnalisés. Une variété de protéines peuvent être explorés dans une large gamme de solutions et de conditions de dénaturation. En outre, ce protocole peut être utilisé pour explorer plus de problèmes de base en utilisant la spectroscopie nanopore.

Watch this Scientific Journal Video about Monitoring Protein Adsorption with Solid-state Nanopores at JoVE.com

Monitoring Protein Adsorption with Solid-state Nanopores

Une méthode d&#39;utilisation de l&#39;état solide nanopores pour surveiller l&#39;adsorption non-spécifique de protéines sur une surface inorganique est décrite. La méthode utilise le principe résistif impulsion, permettant à l&#39;adsorption à sonder en temps réel et à la molécule seul niveau. Parce que le processus d&#39;adsorption est seule protéine loin de l&#39;équilibre, nous proposons l&#39;emploi de réseaux parallèles de nanopores de synthèse, permettant pour la détermination quantitative du taux de réaction de premier ordre apparent constant de l&#39;adsorption des protéines ainsi que l&#39;adsorption de Langmuir et les constantes.

Surveillance des protéines par adsorption à semi-conducteurs Nanopores

Solid-state nanopores have been used to perform measurements at the single-molecule level to examine the local structure and flexibility of nucleic acids ...

monitoring-protein-adsorption-with-solid-state-nanopores

Research

JoVE Journal

Bioengineering

Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring

Nanomedications can be carried by blood borne monocyte-macrophages into the reticuloendothelial system (RES; spleen, liver, lymph nodes) and to end organs. The latter include the lung, RES, and brain and are operative during human immunodeficiency virus type one (HIV-1) infection. Macrophage entry into tissues is notable in areas of active HIV-1 replication and sites of inflammation. In order to assess the potential of macrophages as nanocarriers, superparamagnetic iron-oxide and/or drug laden particles coated with surfactants were parenterally injected into HIV-1 encephalitic mice. This was done to quantitatively assess particle and drug biodistribution. Magnetic resonance imaging (MRI) test results were validated by histological coregistration and enhanced image processing. End organ disease as typified by altered brain histology were assessed by MRI. The demonstration of robust migration of nanoformulations into areas of focal encephalitis provides '"proof of concept" for the use of advanced bioimaging techniques to monitor macrophage migration. Importantly, histopathological aberrations in brain correlate with bioimaging parameters making the general utility of MRI in studies of cell distribution in disease feasible. We posit that using such methods can provide a real time index of disease burden and therapeutic efficacy with translational potential to humans.

Bioimaging methods used to assess cell biodistribution of nanoparticles are applicable for therapeutic and diagnostic monitoring of nanoformulated compounds. The methods described herein are sensitive and specific when assessed by histological coregistration. The methodologies provide a translational pathway from rodent to human applications.

Bioimaging enregistré des nanomatériaux pour la surveillance des services diagnostiques et thérapeutiques

Nanomedications can be carried by blood borne monocyte-macrophages into the reticuloendothelial system (RES; spleen, liver, lymph nodes) and to end ...

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Bio-ingénierie

Fluorescence detection methods for microfluidic droplet platforms

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that accompany system miniaturisation. Advantages include the ability to efficiently process nano- to femoto- liter volumes of sample, facile integration of functional components, an intrinsic predisposition towards large-scale multiplexing, enhanced analytical throughput, improved control and reduced instrumental footprints.1
In recent years much interest has focussed on the development of droplet-based (or segmented flow) microfluidic systems and their potential as platforms in high-throughput experimentation.2-4 Here water-in-oil emulsions are made to spontaneously form in microfluidic channels as a result of capillary instabilities between the two immiscible phases. Importantly, microdroplets of precisely defined volumes and compositions can be generated at frequencies of several kHz. Furthermore, by encapsulating reagents of interest within isolated compartments separated by a continuous immiscible phase, both sample cross-talk and dispersion (diffusion- and Taylor-based) can be eliminated, which leads to minimal cross-contamination and the ability to time analytical processes with great accuracy. Additionally, since there is no contact between the contents of the droplets and the channel walls (which are wetted by the continuous phase) absorption and loss of reagents on the channel walls is prevented.
Once droplets of this kind have been generated and processed, it is necessary to extract the required analytical information. In this respect the detection method of choice should be rapid, provide high-sensitivity and low limits of detection, be applicable to a range of molecular species, be non-destructive and be able to be integrated with microfluidic devices in a facile manner. To address this need we have developed a suite of experimental tools and protocols that enable the extraction of large amounts of photophysical information from small-volume environments, and are applicable to the analysis of a wide range of physical, chemical and biological parameters. Herein two examples of these methods are presented and applied to the detection of single cells and the mapping of mixing processes inside picoliter-volume droplets. We report the entire experimental process including microfluidic chip fabrication, the optical setup and the process of droplet generation and detection.

Droplet-based microfluidic platforms are promising candidates for high throughput experimentation since they are able to generate picoliter, self-compartmentalized vessels inexpensively at kHz rates. Through integration with fast, sensitive and high resolution fluorescence spectroscopic methods, the large amounts of information generated within these systems can be efficiently extracted, harnessed and utilized.

Méthodes de détection par fluorescence pour les plateformes microfluidiques gouttelettes

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that ...

Mass Cytometry: Protocol for Daily Tuning and Running Cell Samples on a CyTOF Mass Cytometer

In recent years, the rapid analysis of single cells has commonly been performed using flow cytometry and fluorescently-labeled antibodies. However, the issue of spectral overlap of fluorophore emissions has limited the number of simultaneous probes. In contrast, the new CyTOF mass cytometer by DVS Sciences couples a liquid single-cell introduction system to an ICP-MS.1 Rather than fluorophores, chelating polymers containing highly-enriched metal isotopes are coupled to antibodies or other specific probes.2-5 Because of the metal purity and mass resolution of the mass cytometer, there is no "spectral overlap" from neighboring isotopes, and therefore no need for compensation matrices. Additionally, due to the use of lanthanide metals, there is no biological background and therefore no equivalent of autofluorescence. With a mass window spanning atomic mass 103-203, theoretically up to 100 labels could be distinguished simultaneously. Currently, more than 35 channels are available using the chelating reagents available from DVS Sciences, allowing unprecedented dissection of the immunological profile of samples.6-7
Disadvantages to mass cytometry include the strict requirement for a separate metal isotope per probe (no equivalent of forward or side scatter), and the fact that it is a destructive technique (no possibility of sorting recovery). The current configuration of the mass cytometer also has a cell transmission rate of only ~25%, thus requiring a higher input number of cells.
Optimal daily performance of the mass cytometer requires several steps. The basic goal of the optimization is to maximize the measured signal intensity of the desired metal isotopes (M) while minimizing the formation of oxides (M+16) that will decrease the M signal intensity and interfere with any desired signal at M+16. The first step is to warm up the machine so a hot, stable ICP plasma has been established. Second, the settings for current and make-up gas flow rate must be optimized on a daily basis. During sample collection, the maximum cell event rate is limited by detector efficiency and processing speed to 1000 cells/sec. However, depending on the sample quality, a slower cell event rate (300-500 cells/sec) is usually desirable to allow better resolution between cells events and thus maximize intact singlets over doublets and debris. Finally, adequate cleaning of the machine at the end of the day helps minimize background signal due to free metal.

The steps necessary for daily tuning and optimization of the performance of a CyTOF mass cytometer are described. Comments on optimal sample preparation and flow rate are discussed

Cytométrie de masse: Protocole pour Tuning quotidien et échantillons cellulaires course sur un cytomètre de masse CyTOF

In recent years, the rapid analysis of single cells has commonly been performed using flow cytometry and fluorescently-labeled antibodies. However, the ...

Multi-analyte Biochip (MAB) Based on All-solid-state Ion-selective Electrodes (ASSISE) for Physiological Research

Lab-on-a-chip (LOC) applications in environmental, biomedical, agricultural, biological, and spaceflight research require an ion-selective electrode (ISE) that can withstand prolonged storage in complex biological media 1-4. An all-solid-state ion-selective-electrode (ASSISE) is especially attractive for the aforementioned applications. The electrode should have the following favorable characteristics: easy construction, low maintenance, and (potential for) miniaturization, allowing for batch processing. A microfabricated ASSISE intended for quantifying H+, Ca2+, and CO32- ions was constructed. It consists of a noble-metal electrode layer (i.e. Pt), a transduction layer, and an ion-selective membrane (ISM) layer. The transduction layer functions to transduce the concentration-dependent chemical potential of the ion-selective membrane into a measurable electrical signal.
The lifetime of an ASSISE is found to depend on maintaining the potential at the conductive layer/membrane interface 5-7. To extend the ASSISE working lifetime and thereby maintain stable potentials at the interfacial layers, we utilized the conductive polymer (CP) poly(3,4-ethylenedioxythiophene) (PEDOT) 7-9 in place of silver/silver chloride (Ag/AgCl) as the transducer layer. We constructed the ASSISE in a lab-on-a-chip format, which we called the multi-analyte biochip (MAB) (Figure 1).
Calibrations in test solutions demonstrated that the MAB can monitor pH (operational range pH 4-9), CO32- (measured range 0.01 mM - 1 mM), and Ca2+ (log-linear range 0.01 mM to 1 mM). The MAB for pH provides a near-Nernstian slope response after almost one month storage in algal medium. The carbonate biochips show a potentiometric profile similar to that of a conventional ion-selective electrode. Physiological measurements were employed to monitor biological activity of the model system, the microalga Chlorella vulgaris.
The MAB conveys an advantage in size, versatility, and multiplexed analyte sensing capability, making it applicable to many confined monitoring situations, on Earth or in space.
Biochip Design and Experimental Methods
The biochip is 10 x 11 mm in dimension and has 9 ASSISEs designated as working electrodes (WEs) and 5 Ag/AgCl reference electrodes (REs). Each working electrode (WE) is 240 &mu;m in diameter and is equally spaced at 1.4 mm from the REs, which are 480 &mu;m in diameter. These electrodes are connected to electrical contact pads with a dimension of 0.5 mm x 0.5 mm. The schematic is shown in Figure 2.
Cyclic voltammetry (CV) and galvanostatic deposition methods are used to electropolymerize the PEDOT films using a Bioanalytical Systems Inc. (BASI) C3 cell stand (Figure 3). The counter-ion for the PEDOT film is tailored to suit the analyte ion of interest. A PEDOT with poly(styrenesulfonate) counter ion (PEDOT/PSS) is utilized for H+ and CO32-, while one with sulphate (added to the solution as CaSO4) is utilized for Ca2+. The electrochemical properties of the PEDOT-coated WE is analyzed using CVs in redox-active solution (i.e. 2 mM potassium ferricyanide (K3Fe(CN)6)). Based on the CV profile, Randles-Sevcik analysis was used to determine the effective surface area 10. Spin-coating at 1,500 rpm is used to cast ~2 &mu;m thick ion-selective membranes (ISMs) on the MAB working electrodes (WEs).
The MAB is contained in a microfluidic flow-cell chamber filled with a 150 &mu;l volume of algal medium; the contact pads are electrically connected to the BASI system (Figure 4). The photosynthetic activity of Chlorella vulgaris is monitored in ambient light and dark conditions.

Multi-analyte Biochip MAB Based on All-solid-state Ion-selective Electrodes ASSISE for Physiological Research

All-solid-state ion-selective electrodes (ASSISEs) constructed from a conductive polymer (CP) transducer provide several months of functional lifetime in liquid media. Here, we describe the fabrication and calibration process of ASSISEs in a lab-on-a-chip format. The ASSISE is demonstrated to have maintained a near-Nernstian slope profile after prolonged storage in complex biological media.

Biochip multi-analyte (MAB) Basé sur des électrodes sélectives d&#39;ions All-état solide (ASSISE) pour la recherche physiologique

Lab-on-a-chip (LOC) applications in environmental, biomedical, agricultural, biological, and spaceflight research require an ion-selective electrode (ISE) ...

Multi-Scale Modification of Metallic Implants With Pore Gradients, Polyelectrolytes and Their Indirect Monitoring In vivo

Metallic implants, especially titanium implants, are widely used in clinical applications. Tissue in-growth and integration to these implants in the tissues are important parameters for successful clinical outcomes. In order to improve tissue integration, porous metallic implants have being developed. Open porosity of metallic foams is very advantageous, since the pore areas can be functionalized without compromising the mechanical properties of the whole structure. Here we describe such modifications using porous titanium implants based on titanium microbeads. By using inherent physical properties such as hydrophobicity of titanium, it is possible to obtain hydrophobic pore gradients within microbead based metallic implants and at the same time to have a basement membrane mimic based on hydrophilic, natural polymers. 3D pore gradients are formed by synthetic polymers such as Poly-L-lactic acid (PLLA) by freeze-extraction method. 2D nanofibrillar surfaces are formed by using collagen/alginate followed by a crosslinking step with a natural crosslinker (genipin). This nanofibrillar film was built up by layer by layer (LbL) deposition method of the two oppositely charged molecules, collagen and alginate. Finally, an implant where different areas can accommodate different cell types, as this is necessary for many multicellular tissues, can be obtained. By, this way cellular movement in different directions by different cell types can be controlled. Such a system is described for the specific case of trachea regeneration, but it can be modified for other target organs. Analysis of cell migration and the possible methods for creating different pore gradients are elaborated. The next step in the analysis of such implants is their characterization after implantation. However, histological analysis of metallic implants is a long and cumbersome process, thus for monitoring host reaction to metallic implants in vivo an alternative method based on monitoring CGA and different blood proteins is also described. These methods can be used for developing in vitro custom-made migration and colonization tests and also be used for analysis of functionalized metallic implants in vivo without histology.

Multi-Scale Modification of Metallic Implants With Pore Gradients, Polyelectrolytes and Their Indirect Monitoring In vivo

In this video, we will demonstrate modification techniques for porous metallic implants to improve their functionality and to control cell migration. Techniques include development of pore gradients to control cell movement in 3D and production of basement membrane mimics to control cell movement in 2-D. Also, a HPLC-based method for monitoring implant integration in-vivo via analysis of blood proteins is described.

Modification multi-échelle des implants métalliques avec des gradients des pores, polyélectrolytes et leur surveillance indirecte<em&gt; In vivo</em

Metallic implants, especially titanium implants, are widely used in  clinical applications. Tissue in-growth and integration to these implants in  the ...

Construction and Setup of a Bench-scale Algal Photosynthetic Bioreactor with Temperature, Light, and pH Monitoring for Kinetic Growth Tests

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth parameters used in these models must be accurately determined. Algal growth experiments are often constrained by the dynamic nature of the culture environment, and control systems are needed to accurately determine the kinetic parameters. The first step in setting up a controlled batch experiment is live data acquisition and monitoring. This protocol outlines a process for the assembly and operation of a bench-scale photosynthetic bioreactor that can be used to conduct microalgal growth experiments. This protocol describes how to size and assemble a flat-plate, bench-scale PBR from acrylic. It also details how to configure a PBR with continuous pH, light, and temperature monitoring using a data acquisition and control unit, analog sensors, and open-source data acquisition software.

This paper describes the assembly process and operation of a bench-scale photosynthetic bioreactor that can be used, in conjunction with other methods, to estimate pertinent kinetic growth parameters. This system continuously monitors the pH, light, and temperature using sensors, a data acquisition and control unit, and open-source data acquisition software.

Construction et mise en place d&#39;un bioréacteur photosynthétique Algal à échelle de banc avec surveillance de la température, de la lumière et du pH pour les tests de croissance cinétique

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic ...

In Vesiculo Synthesis of Peptide Membrane Precursors for Autonomous Vesicle Growth

Compartmentalization of biochemical reactions is a central aspect of synthetic cells. For this purpose, peptide-based reaction compartments serve as an attractive alternative to liposomes or fatty acid-based vesicles. Externally or within the vesicles, peptides can be easily expressed and simplify the synthesis of membrane precursors. Provided here is a protocol for the creation of vesicles with diameters of ~200 nm based on the amphiphilic elastin-like polypeptides (ELP) utilizing dehydration-rehydration from glass beads. Also presented are protocols for bacterial ELP expression and purification via inverse temperature cycling, as well as their covalent functionalization with fluorescent dyes. Furthermore, this report describes a protocol to enable the transcription of RNA aptamer dBroccoli inside ELP vesicles as a less complex example for a biochemical reaction. Finally, a protocol is provided, which allows in vesiculo expression of fluorescent proteins and the membrane peptide, whereas synthesis of the latter results in vesicle growth.

Presented here are protocols for the creation of peptide-based small unilamellar vesicles capable of growth. To facilitate in vesiculo production of the membrane peptide, these vesicles are equipped with a transcription-translation system and the peptide-encoding plasmid.

Dans Vesiculo Synthesis of Peptide Membrane Precursors for Autonomous Vesicle Growth

Compartmentalization of biochemical reactions is a central aspect of synthetic cells. For this purpose, peptide-based reaction compartments serve as an ...

Functional Transcranial Doppler Ultrasound for Monitoring Cerebral Blood Flow

Functional transcranial Doppler ultrasound (fTCD) is the use of transcranial Doppler ultrasound (TCD) to study neural activation occurring during stimuli such as physical movement, activation of tactile sensors in the skin, and viewing images. Neural activation is inferred from an increase in the cerebral blood flow velocity (CBFV) supplying the region of the brain involved in processing sensory input. For example, viewing bright light causes increased neural activity in the occipital lobe of the cerebral cortex, leading to increased blood flow in the posterior cerebral artery, which supplies the occipital lobe. In fTCD, changes in CBFV are used to estimate changes in cerebral blood flow (CBF).
With its high temporal resolution measurement of blood flow velocities in the major cerebral arteries, fTCD complements other established functional imaging techniques. The goal of this Methods paper is to give step-by-step instructions for using fTCD to perform a functional imaging experiment. First, the basic steps for identifying the middle cerebral artery (MCA) and optimizing the signal will be described. Next, placement of a fixation device for holding the TCD probe in place during the experiment will be described. Finally, the breath-holding experiment, which is a specific example of a functional imaging experiment using fTCD, will be demonstrated.

Functional transcranial Doppler ultrasound complements other functional imaging modalities, with its high temporal resolution measurement of stimulus-induced changes in cerebral blood flow within the basal cerebral arteries. This Methods paper gives step-by-step instructions for using functional transcranial Doppler ultrasound to perform a functional imaging experiment.&#160;

Échographie Doppler transcrânienne fonctionnelle pour la surveillance du flux sanguin cérébral

Functional transcranial Doppler ultrasound (fTCD) is the use of transcranial Doppler ultrasound (TCD) to study neural activation occurring during stimuli ...

Construction of a Wireless-Enabled Endoscopically Implantable Sensor for pH Monitoring with Zero-Bias Schottky Diode-based Receiver

Ambulatory pH monitoring of pathological reflux is an opportunity to observe the relationship between symptoms and exposure of the esophagus to acidic or non-acidic refluxate. This paper describes a method for the development, manufacturing, and implantation of a miniature wireless-enabled pH sensor. The sensor is designed to be implanted endoscopically with a single hemostatic clip. A fully passive rectenna-based receiver based on a zero-bias Schottky diode is also constructed and tested. To construct the device, a two-layer printed circuit board and off-the-shelf components were used. A miniature microcontroller with integrated analog peripherals is used as an analog front end for the ion-sensitive field-effect transistor (ISFET) sensor and to generate a digital signal which is transmitted with an amplitude shift keying transmitter chip. The device is powered by two primary alkaline cells. The implantable device has a total volume of 0.6 cm3 and a weight of 1.2 grams, and its performance was verified in an ex vivo model (porcine esophagus and stomach). Next, a small footprint passive rectenna-based receiver which can be easily integrated either into an external receiver or the implantable neurostimulator, was constructed and proven to receive the RF signal from the implant when in proximity (20 cm) to it. The small size of the sensor provides continuous pH monitoring with minimal obstruction of the esophagus. The sensor could be used in routine clinical practice for 24/96 h esophageal pH monitoring without the need to insert a nasal catheter. The &#34;zero-power&#34; nature of the receiver also enables the use of the sensor for automatic in-vivo calibration of miniature lower esophageal sphincter neurostimulation devices. An active sensor-based control enables the development of advanced algorithms to minimize the used energy to achieve a desirable clinical outcome. One of the examples of such an algorithm would be a closed-loop system for on-demand neurostimulation therapy of gastroesophageal reflux disease (GERD).

The manuscript presents a miniature implantable pH sensor with ASK modulated wireless output together with a fully passive receiver circuit based on zero-bias Schottky diodes. This solution can be used as a basis in the development of in vivo calibrated electrostimulation therapy devices and for ambulatory pH monitoring.

Construction d’un capteur implantable par endoscopie sans fil pour la surveillance du pH avec récepteur à diode Schottky à polarisation nulle

Ambulatory pH monitoring of pathological reflux is an opportunity to observe the relationship between symptoms and exposure of the esophagus to acidic or ...

Coral Growth and Monitoring Using the Micro-Device System

After setting the micro drive system, add one milliliter of the commercial microbiome source solution into 500 milliliters of the seawater while stirring. Next, inject 50 milliliters of the diluted solution and 10 microliters of the commercial coral nutrition solution into the circulation system. Switch on the inner circulation pump and turn on the air pump to culture the microbiome for 21 days.Cut the rock coral branches into a length of three to five centimeters. Adhere these coral branches onto 3D-printed coral support bases. Place the coral branch samples back into the original seawater tank for a minimum of seven days for recovery.Fix the coral support base onto the rotation unit using glue. Assemble the coral culture module and connect it to the outer circulation loop. Position the camera on the top of the studio and capture the images from a vertical view.Next, place the coral culture module in the mini photo studio with the coral positioned in the center and at the bottom. Capture coral images by rotating the outside handle. The coral culture module effectively controlled the seawater temperature and prevented temperature fluctuation, which can strongly affect coral survival.The sample corals'tentacles extended over one month indicating that the system provided a suitable survival environment for the coral.