Two Contrasting Failure Modes of Enteric Coated Beads.

Science.gov (United States)

Shi, Galen H; Dong, Xia; Lytle, Michelle; Kemp, Craig A J; Behme, Robert J; Hinds, Jeremy; Xiao, Zhicheng

2018-04-09

This study aimed to elucidate the mechanisms and kinetics of coating failure for enteric coated beads exposed to high-humidity conditions at different storage temperatures. Enteric coated beads were placed on high-humidity conditions (75 to 98% relative humidity (RH)) in the temperature range of 5 to 40°C. These stability samples of beads were tested for acid dissolution and water activity and also analyzed with SEM, X-ray CT, and DMA. Exposure of enteric coated beads to high humidity led to increased gastric release of drug which eventually failed the dissolution specification. SEM showed visible cracks on the surface of beads exposed to 5°C/high humidity and fusion of enteric beads into agglomerates at 40°C/high humidity. In a non-destructive time elapse study, X-ray CT demonstrated swelling of microcrystalline cellulose cores, crack initiation, and propagation through the API layer within days under 5°C/98% RH storage conditions and ultimately fracture through the enteric coating. DMA data showed a marked reduction in T g of the enteric coating materials after exposure to humidity. At 5°C/high humidity, the hygroscopic microcrystalline cellulose core absorbed moisture leading to core swelling and consequent fracture through the brittle API and enteric layers. At 40°C (high humidity) which is above the T g of the enteric polymer, enteric coated beads coalesced into agglomerates due to melt flow of the enteric coating. We believe it is the first report on two distinct failure models of enteric coated dosage forms.

Magnetic nanoparticle-loaded alginate beads for local micro-actuation of in vitro tissue constructs.

Science.gov (United States)

Alshehri, Awatef M; Wilson, Otto C; Dahal, Bishnu; Philip, John; Luo, Xiaolong; Raub, Christopher B

2017-11-01

Magnetic nanoparticles (MNPs) self-align and transduce magnetic force, two properties which lead to promising applications in cell and tissue engineering. However, the toxicity of MNPs to cells which uptake them is a major impediment to applications in engineered tissue constructs. To address this problem, MNPs were embedded in millimeter-scale alginate beads, coated with glutaraldehyde cross-linked chitosan, and loaded in acellular and MDA-MB-231 cancer cell-seeded collagen hydrogels, providing local micro-actuation under an external magnetic field. Brightfield microscopy was used to assess nanoparticle diffusion from the bead. Phase contrast microscopy and digital image correlation were used to track collagen matrix displacement and estimate intratissue strain under magnetic actuation. Coating the magnetic alginate beads with glutaraldehyde-chitosan prevents bulk diffusion of nanoparticles into the surrounding microenvironment. Further, the beads exert force on the surrounding collagen gel and cells, resulting in intratissue strains of 0-10% tunable with bead dimensions, collagen density, and distance from the bead. Cells seeded adjacent to the embedded beads are subjected to strain gradients without loss of cell viability over two days culture. This study describes a simple way to fabricate crosslinked magnetic alginate beads to load in a collagen tissue construct without direct exposure of the construct to nanoparticles. The findings are significant to in vitro studies of mechanobiology in enabling precise control over dynamic mechanical loading of tissue constructs. Copyright © 2017 Elsevier B.V. All rights reserved.

Osseoconductivity of a Specific Streptavidin-Biotin-Fibronectin Surface Coating of Biotinylated Titanium Implants - A Rabbit Animal Study.

Science.gov (United States)

Kämmerer, Peer W; Lehnert, Michael; Al-Nawas, Bilal; Kumar, Vinay V; Hagmann, Sebastien; Alshihri, Abdulmonem; Frerich, Bernhard; Veith, Michael

2015-10-01

Biofunctionalized implant surfaces may accelerate bony integration and increase long-term stability. The aim of the study was to evaluate the osseous reaction toward biomimetic titanium implants surfaces coated with quasicovalent immobilized fibronectin in an in vivo animal model. A total of 84 implants (uncoated [control 1, n = 36], streptavidin-biotin coated [test 1, n = 24], streptavidin-biotin-fibronectin coated [test 2, n = 24]) were inserted 1 mm supracortically in the proximal tibia of 12 rabbits. The samples were examined after 3 and 6 weeks. Total bone-implant contact (tBIC; %), bone-implant contact in the cortical (cBIC; %) and in the spongious bone (sBIC; %) as well as the percentage of linear bone fill (PLF; %) were evaluated. After 3 weeks, streptavidin-biotin-fibronectin implants had a significant higher sBIC (p = .043) and PLF (p = .007) compared with the uncoated samples. After 6 weeks, this difference was significant for tBIC (p = .016) and cBIC (p biotin-coated implants showed less bone growth at both time points of all examined parameters when compared with their counterparts (all p biotin-fibronectin system on smooth surface titanium shows a beneficial faster osseous healing in vivo. Besides, an antifouling effect of the streptavidin-biotin coating was proven. © 2015 Wiley Periodicals, Inc.

Acetylcholinesterase immobilized capillary reactors coupled to protein coated magnetic beads: A new tool for plant extract ligand screening

Science.gov (United States)

Vanzolini, Kenia Lourenço; Jiang, Zhengjin; Zhang, Xiaoqi; Vieira, Lucas Campos Curcino; Corrêa, Arlene Gonçalvez; Cardoso, Carmen Lucia; Cass, Quezia Bezerra; Moaddel, Ruin

2013-01-01

The use of immobilized capillary enzyme reactors (ICERs) and enzymes coated to magnetic beads ((NT or CT)-MB) for ligand screening has been adopted as a new technique of high throughput screening (HTS). In this work the selected target was the enzyme acetylcholinesterase (AChE), which acts on the central nervous system and is a validated target for the treatment of Alzheimer’s disease, as well as for new insecticides. A new approach for the screening of plant extracts was developed based on the ligand fishing experiments and zonal chromatography. For that, the magnetic beads were used for the ligand fishing experiments and capillary bioreactors for the activity assays. The latter was employed also under non-linear conditions to determine the affinity constants of known ligands, for the first time, as well as for the active fished ligand. PMID:24148457

Highly Specific Binding on Antifouling Zwitterionic Polymer-Coated Microbeads as Measured by Flow Cytometry.

Science.gov (United States)

van Andel, Esther; de Bus, Ian; Tijhaar, Edwin J; Smulders, Maarten M J; Savelkoul, Huub F J; Zuilhof, Han

2017-11-08

Micron- and nano-sized particles are extensively used in various biomedical applications. However, their performance is often drastically hampered by the nonspecific adsorption of biomolecules, a process called biofouling, which can cause false-positive and false-negative outcomes in diagnostic tests. Although antifouling coatings have been extensively studied on flat surfaces, their use on micro- and nanoparticles remains largely unexplored, despite the widespread experimental (specifically, clinical) uncertainties that arise because of biofouling. Here, we describe the preparation of magnetic micron-sized beads coated with zwitterionic sulfobetaine polymer brushes that display strong antifouling characteristics. These coated beads can then be equipped with recognition elements of choice, to enable the specific binding of target molecules. First, we present a proof of principle with biotin-functionalized beads that are able to specifically bind fluorescently labeled streptavidin from a complex mixture of serum proteins. Moreover, we show the versatility of the method by demonstrating that it is also possible to functionalize the beads with mannose moieties to specifically bind the carbohydrate-binding protein concanavalin A. Flow cytometry was used to show that thus-modified beads only bind specifically targeted proteins, with minimal/near-zero nonspecific protein adsorption from other proteins that are present. These antifouling zwitterionic polymer-coated beads, therefore, provide a significant advancement for the many bead-based diagnostic and other biosensing applications that require stringent antifouling conditions.

Magnetic bead detection using nano-transformers

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyung Kwon; Ahn, Doyeol [Institute of Quantum Information Processing and Systems, University of Seoul, 90 Jeonnong, Dongdaemun, Seoul 130-743 (Korea, Republic of); Hwang, Jong Seung; Hwang, Sung Woo, E-mail: dahn@uos.ac.kr [Research Center for Time-domain Nano-functional Devices and School of Electrical Engineering, Korea University, 5-1 Anam, Sungbuk, Seoul 136-701 (Korea, Republic of)

2010-11-19

A novel scheme to detect magnetic beads using a nano-scale transformer with a femtoweber resolution is reported. We have performed a Faraday's induction experiment with the nano-transformer at room temperature. The transformer shows the linear output voltage responses to the sinusoidal input current. When magnetic beads are placed on the transformer, the output responses are increased by an amount corresponding to the added magnetic flux from the beads when compared with the case of no beads on the transformer. In this way, we could determine whether magnetic beads are on top of the transformer in a single particle level.

Magnetic bead detection using nano-transformers.

Science.gov (United States)

Kim, Hyung Kwon; Hwang, Jong Seung; Hwang, Sung Woo; Ahn, Doyeol

2010-11-19

A novel scheme to detect magnetic beads using a nano-scale transformer with a femtoweber resolution is reported. We have performed a Faraday's induction experiment with the nano-transformer at room temperature. The transformer shows the linear output voltage responses to the sinusoidal input current. When magnetic beads are placed on the transformer, the output responses are increased by an amount corresponding to the added magnetic flux from the beads when compared with the case of no beads on the transformer. In this way, we could determine whether magnetic beads are on top of the transformer in a single particle level.

Microfluidic magnetic bead conveyor belt.

Science.gov (United States)

van Pelt, Stijn; Frijns, Arjan; den Toonder, Jaap

2017-11-07

Magnetic beads play an important role in the miniaturization of clinical diagnostics systems. In lab-on-chip platforms, beads can be made to link to a target species and can then be used for the manipulation and detection of this species. Current bead actuation systems utilize complex on-chip coil systems that offer low field strengths and little versatility. We demonstrate a novel system based on an external rotating magnetic field and on-chip soft-magnetic structures to focus the field locally. These structures were designed and optimized using finite element simulations in order to create a number of local flux density maxima. These maxima, to which the magnetic beads are attracted, move over the chip surface in a continuous way together with the rotation of the external field, resulting in a mechanism similar to that of a conveyor belt. A prototype was fabricated using PDMS molding techniques mixed with iron powder for the magnetic structures. In the subsequent experiments, a quadrupole electromagnet was used to create the rotating external field. We observed that beads formed agglomerates that rolled over the chip surface, just above the magnetic structures. Field rotation frequencies between 0.1-50 Hz were tested resulting in magnetic bead speeds of over 1 mm s -1 for the highest frequency. With this, we have shown that our novel concept works, combining a simple design and simple operation with a powerful and versatile method for bead actuation. This makes it a promising method for further research and utilization in lab-on-chip systems.

Microfabricated Passive Magnetic Bead separators

DEFF Research Database (Denmark)

Hansen, Mikkel Fougt; Lund-Olesen, Torsten; Smistrup, Kristian

2006-01-01

The use and manipulation of functionalized magnetic beads for bioanalysis in lab-on-a-chip systems is receiving growing interest. We have developed microfluidic systems with integrated magnetic structures for the capture and release of magnetic beads. The systems are fabricated in silicon by deep...

PRELIMINARY STUDY ON RETRO-REFLECTIVE COATED PAPER BASED ON MICRO-GLASS BEADS

Institute of Scientific and Technical Information of China (English)

YulongWang; ChuanshanZhao; TaoZhang

2004-01-01

High-reflectivity micro-glass bead, as a kind ofretro-reflective material, is widely used in reflectivefabric or film and other reflective coatings. But it israrely used in coated paper. The retro-reflectivetheory of micro-bead is described. Also the effect ofsize of micro-bead, dosage of binder and differentcolor layers on reflective properties of coated paperare discussed in this article. The results show that itsretro-reflective efficiency is good, equally toreflective fabric or film when the micro-glass bead isused in coated paper.

A disposable electrochemical immunosensor for prolactin involving affinity reaction on streptavidin-functionalized magnetic particles

International Nuclear Information System (INIS)

Moreno-Guzman, Maria; Gonzalez-Cortes, Araceli; Yanez-Sedeno, Paloma; Pingarron, Jose M.

2011-01-01

A novel electrochemical immunosensor was developed for the determination of the hormone prolactin. The design involved the use of screen-printed carbon electrodes and streptavidin-functionalized magnetic particles. Biotinylated anti-prolactin antibodies were immobilized onto the functionalized magnetic particles and a sandwich-type immunoassay involving prolactin and anti-prolactin antibody labelled with alkaline phosphatase was employed. The resulting bio-conjugate was trapped on the surface of the screen-printed electrode with a small magnet and prolactin quantification was accomplished by differential pulse voltammetry of 1-naphtol formed in the enzyme reaction using 1-naphtyl phosphate as alkaline phosphatase substrate. All variables involved in the preparation of the immunosensor and in the electrochemical detection step were optimized. The calibration plot for prolactin exhibited a linear range between 10 and 2000 ng mL -1 with a slope value of 7.0 nA mL ng -1 . The limit of detection was 3.74 ng mL -1 . Furthermore, the modified magnetic beads-antiprolactin conjugates showed an excellent stability. The immunosensor exhibited also a high selectivity with respect to other hormones. The analytical usefulness of the immnunosensor was demonstrated by analyzing human sera spiked with prolactin at three different concentration levels.

A disposable electrochemical immunosensor for prolactin involving affinity reaction on streptavidin-functionalized magnetic particles

Energy Technology Data Exchange (ETDEWEB)

Moreno-Guzman, Maria; Gonzalez-Cortes, Araceli [Department of Analytical Chemistry, Faculty of Chemistry, University Computense of Madrid, 28040 Madrid (Spain); Yanez-Sedeno, Paloma, E-mail: yseo@quim.ucm.es [Department of Analytical Chemistry, Faculty of Chemistry, University Computense of Madrid, 28040 Madrid (Spain); Pingarron, Jose M. [Department of Analytical Chemistry, Faculty of Chemistry, University Computense of Madrid, 28040 Madrid (Spain)

2011-04-29

A novel electrochemical immunosensor was developed for the determination of the hormone prolactin. The design involved the use of screen-printed carbon electrodes and streptavidin-functionalized magnetic particles. Biotinylated anti-prolactin antibodies were immobilized onto the functionalized magnetic particles and a sandwich-type immunoassay involving prolactin and anti-prolactin antibody labelled with alkaline phosphatase was employed. The resulting bio-conjugate was trapped on the surface of the screen-printed electrode with a small magnet and prolactin quantification was accomplished by differential pulse voltammetry of 1-naphtol formed in the enzyme reaction using 1-naphtyl phosphate as alkaline phosphatase substrate. All variables involved in the preparation of the immunosensor and in the electrochemical detection step were optimized. The calibration plot for prolactin exhibited a linear range between 10 and 2000 ng mL{sup -1} with a slope value of 7.0 nA mL ng{sup -1}. The limit of detection was 3.74 ng mL{sup -1}. Furthermore, the modified magnetic beads-antiprolactin conjugates showed an excellent stability. The immunosensor exhibited also a high selectivity with respect to other hormones. The analytical usefulness of the immnunosensor was demonstrated by analyzing human sera spiked with prolactin at three different concentration levels.

Acetylcholinesterase immobilized capillary reactors coupled to protein coated magnetic beads: A new tool for plant extract ligand screening

OpenAIRE

Vanzolini, Kenia Lourenço; Jiang, Zhengjin; Zhang, Xiaoqi; Vieira, Lucas Campos Curcino; Corrêa, Arlene Gonçalvez; Cardoso, Carmen Lucia; Cass, Quezia Bezerra; Moaddel, Ruin

2013-01-01

The use of immobilized capillary enzyme reactors (ICERs) and enzymes coated to magnetic beads ((NT or CT)-MB) for ligand screening has been adopted as a new technique of high throughput screening (HTS). In this work the selected target was the enzyme acetylcholinesterase (AChE), which acts on the central nervous system and is a validated target for the treatment of Alzheimer’s disease, as well as for new insecticides. A new approach for the screening of plant extracts was developed based on t...

PRELIMINARY STUDY ON RETRO-REFLECTIVE COATED PAPER BASED ON MICRO-GLASS BEADS

Institute of Scientific and Technical Information of China (English)

Yulong Wang; Chuanshan Zhao; Tao Zhang

2004-01-01

High-reflectivity micro-glass bead, as a kind of retro-reflective material, is widely used in reflective fabric or film and other reflective coatings. But it is rarely used in coated paper. The retro-reflective theory of micro-bead is described. Also the effect of size of micro-bead, dosage of binder and different color layers on reflective properties of coated paper are discussed in this article. The results show that its retro-reflective efficiency is good, equally to reflective fabric or film when the micro-glass bead is used in coated paper.

A Phos-tag-based magnetic-bead method for rapid and selective separation of phosphorylated biomolecules.

Science.gov (United States)

Tsunehiro, Masaya; Meki, Yuma; Matsuoka, Kanako; Kinoshita-Kikuta, Emiko; Kinoshita, Eiji; Koike, Tohru

2013-04-15

A simple and efficient method based on magnetic-bead technology has been developed for the separation of phosphorylated and nonphosphorylated low-molecular-weight biomolecules, such as nucleotides, phosphorylated amino acids, or phosphopeptides. The phosphate-binding site on the bead is an alkoxide-bridged dinuclear zinc(II) complex with 1,3-bis(pyridin-2-ylmethylamino)propan-2-olate (Phos-tag), which is linked to a hydrophilic cross-linked agarose coating on a magnetic core particle. All steps for the phosphate-affinity separation are conducted in buffers of neutral pH with 50 μL of the magnetic beads in a 1.5-mL microtube. The entire separation protocol for phosphomonoester-type compounds, from addition to elution, requires less than 12 min per sample if the buffers and the zinc(II)-bound Phos-tag magnetic beads have been prepared in advance. The phosphate-affinity magnetic beads are reusable at least 15 times without a decrease in their phosphate-binding ability and they are stable for three months in propan-2-ol. Copyright © 2013 Elsevier B.V. All rights reserved.

Rapid, highly sensitive detection of herpes simplex virus-1 using multiple antigenic peptide-coated superparamagnetic beads.

Science.gov (United States)

Ran, Ying-Fen; Fields, Conor; Muzard, Julien; Liauchuk, Viktoryia; Carr, Michael; Hall, William; Lee, Gil U

2014-12-07

A sensitive, rapid, and label free magnetic bead aggregation (MBA) assay has been developed that employs superparamagnetic (SPM) beads to capture, purify, and detect model proteins and the herpes simplex virus (HSV). The MBA assay is based on monitoring the aggregation state of a population of SPM beads using light scattering of individual aggregates. A biotin-streptavidin MBA assay had a femtomolar (fM) level sensitivity for analysis times less than 10 minutes, but the response of the assay becomes nonlinear at high analyte concentrations. A MBA assay for the detection of HSV-1 based on a novel peptide probe resulted in the selective detection of the virus at concentrations as low as 200 viral particles (vp) per mL in less than 30 min. We define the parameters that determine the sensitivity and response of the MBA assay, and the mechanism of enhanced sensitivity of the assay for HSV. The speed, relatively low cost, and ease of application of the MBA assay promise to make it useful for the identification of viral load in resource-limited and point-of-care settings where molecular diagnostics cannot be easily implemented.

Electrochemical biotin detection based on magnetic beads and a new magnetic flow cell for screen printed electrode.

Science.gov (United States)

Biscay, Julien; González García, María Begoña; Costa García, Agustín

2015-01-01

The use of the first flow-cell for magnetic assays with an integrated magnet is reported here. The flow injection analysis system (FIA) is used for biotin determination. The reaction scheme is based on a one step competitive assay between free biotin and biotin labeled with horseradish peroxidase (B-HRP). The mixture of magnetic beads modified with streptavidin (Strep-MB), biotin and B-HRP is left 15 min under stirring and then a washing step is performed. After that, 100 μL of the mixture is injected and after 30s 100 μL of 3,3',5,5'-Tetramethylbenzidine (TMB) is injected and the FIAgram is recorded applying a potential of -0.2V. The linear range obtained is from 0.01 to 1 nM of biotin and the sensitivity is 758 nA/nM. The modification and cleaning of the electrode are performed in an easy way due to the internal magnet of the flow cell. Copyright © 2014 Elsevier B.V. All rights reserved.

Self-organizing magnetic beads for biomedical applications

International Nuclear Information System (INIS)

Gusenbauer, Markus; Kovacs, Alexander; Reichel, Franz; Exl, Lukas; Bance, Simon; Özelt, Harald; Schrefl, Thomas

2012-01-01

In the field of biomedicine magnetic beads are used for drug delivery and to treat hyperthermia. Here we propose to use self-organized bead structures to isolate circulating tumor cells using lab-on-chip technologies. Typically blood flows past microposts functionalized with antibodies for circulating tumor cells. Creating these microposts with interacting magnetic beads makes it possible to tune the geometry in size, position and shape. We developed a simulation tool that combines micromagnetics and discrete particle dynamics, in order to design micropost arrays made of interacting beads. The simulation takes into account the viscous drag of the blood flow, magnetostatic interactions between the magnetic beads and gradient forces from external aligned magnets. We developed a particle–particle particle–mesh method for effective computation of the magnetic force and torque acting on the particles. - Highlights: ► We propose to use self-organized bead structures to isolate circulating tumor cells. ► Flexible ways are important to get a high probability of catching cancer cells. ► The beads make it possible to tune the geometry in size position and shape.

Microfluidic magnetic bead conveyor belt

NARCIS (Netherlands)

van Pelt, S.; Frijns, A.J.H.; den Toonder, J.M.J.

2017-01-01

Magnetic beads play an important role in the miniaturization of clinical diagnostics systems. In lab-on-chip platforms, beads can be made to link to a target species and can then be used for the manipulation and detection of this species. Current bead actuation systems utilize complex on-chip coil

Rapid and reagent-saving immunoassay using innovative stirring actions of magnetic beads in microreactors in the sequential injection mode.

Science.gov (United States)

Tanaka, K; Imagawa, H

2005-12-15

We developed new ELISA techniques in sequential injection analysis (SIA) mode using microreactors with content of a few microliters. We immobilized antibodies on magnetic beads 1.0mum in diameter, injected the beads into microreactors and applied rotating magnetic fields of several hundred gauss. Magnetic beads, suspended in liquid in density of approximately 10(9)-10(10) particles per millilitre, form a large number of thin rod clusters, whose length-wise axes are oriented in parallel with the magnetic field. We rotate the Nd magnets below the center of the microreactor by a tiny motor at about 2000-5000rpm. These rotating clusters remarkably accelerate the binding rate of the antibodies with antigens in the liquid. The beads are trapped around the center of the rotating magnetic field even in the flowing liquid. This newly found phenomenon enables easy bead handling in microreactors. Modification of reactor walls with selected blocking reagents was essential, because protein-coated beads often stick to the wall surface and cannot move freely. Washing steps were also shortened.

Quantification of specific bindings of biomolecules by magnetorelaxometry

Directory of Open Access Journals (Sweden)

Steinhoff Uwe

2008-03-01

Full Text Available Abstract The binding reaction of the biomolecules streptavidin and anti-biotin antibody, both labelled by magnetic nanoparticles (MNP, to biotin coated on agarose beads, was quantified by magnetorelaxometry (MRX. Highly sensitive SQUID-based MRX revealed the immobilization of the MNP caused by the biotin-streptavidin coupling. We found that about 85% of streptavidin-functionalised MNP bound specifically to biotin-agarose beads. On the other hand only 20% of antibiotin-antibody functionalised MNP were specifically bound. Variation of the suspension medium revealed in comparison to phosphate buffer with 0.1% bovine serum albumin a slight change of the binding behaviour in human serum, probably due to the presence of functioning (non heated serum proteins. Furthermore, in human serum an additional non-specific binding occurs, being independent from the serum protein functionality. The presented homogeneous bead based assay is applicable in simple, uncoated vials and it enables the assessment of the binding kinetics in a volume without liquid flow. The estimated association rate constant for the MNP-labelled streptavidin is by about two orders of magnitude smaller than the value reported for free streptavidin. This is probably due to the relatively large size of the magnetic markers which reduces the diffusion of streptavidin. Furthermore, long time non-exponential kinetics were observed and interpreted as agglutination of the agarose beads.

Magnetic bead micromixer: Influence of magnetic element geometry and field amplitude

DEFF Research Database (Denmark)

Lund-Olesen, Torsten; Buus, Bjarke B.; Howalt, Jakob

2008-01-01

A scheme for the silicon microfabrication of lab-on-a-chip systems with mixing based on dynamic plugs of magnetic beads is presented. The systems consist of a microfluidic channel integrated with a number of soft magnetic elements by the sides of the channel. The elements are magnetized by a homo......A scheme for the silicon microfabrication of lab-on-a-chip systems with mixing based on dynamic plugs of magnetic beads is presented. The systems consist of a microfluidic channel integrated with a number of soft magnetic elements by the sides of the channel. The elements are magnetized...... by a homogeneous external ac magnetic field. The systems are scalable with respect to the number of magnetic bead plugs and number of parallel channels, and thus they have high potential for use in biological separation using functionalized magnetic beads. The mixing efficiency is characterized for two different...

Configurational Statistics of Magnetic Bead Detection with Magnetoresistive Sensors

DEFF Research Database (Denmark)

Henriksen, Anders Dahl; Ley, Mikkel Wennemoes Hvitfeld; Flyvbjerg, Henrik

2015-01-01

Magnetic biosensors detect magnetic beads that, mediated by a target, have bound to a functionalized area. This area is often larger than the area of the sensor. Both the sign and magnitude of the average magnetic field experienced by the sensor from a magnetic bead depends on the location...... of the bead relative to the sensor. Consequently, the signal from multiple beads also depends on their locations. Thus, a given coverage of the functionalized area with magnetic beads does not result in a given detector response, except on the average, over many realizations of the same coverage. We present...... a systematic theoretical analysis of how this location-dependence affects the sensor response. The analysis is done for beads magnetized by a homogeneous in-plane magnetic field. We determine the expected value and standard deviation of the sensor response for a given coverage, as well as the accuracy...

Highly specific and rapid immuno-fluorescent visualization and detection of E. coli O104:H4 with protein-A coated magnetic beads based LST-MUG assay.

Science.gov (United States)

Barizuddin, Syed; Balakrishnan, Baskar; Stringer, R Cody; Dweik, Majed

2015-08-01

A method combining immunomagnetic separation and fluorescent sensing was developed to detect Escherichia coli (E. coli) O104:H4. The antibody specific to E. coli O104:H4 was immobilized on protein A-coated magnetic beads. This protein-A-anti E. coli O104:H4 complex was used to bind Fluorescein IsoThioCyanate (FITC) labeled E. coli O104:H4 antigen (whole cell) on it. The goal was to achieve a fluorescently detectable protein-A-anti E. coli O104:H4-E. coli O104:H4 complex on the magnetic beads. Fluorescent microscopy was used to image the magnetic beads. The resulting fluorescence on the beads was due to the FITC labeled antigen binding on the protein-A-anti E. coli O104:H4 immobilized magnetic beads. This visually proves the antigen-antibody binding. The fluorescent imaging results were obtained in 2 h if the minimum available bacteria in the sample were at least 10(5) CFU/ml. If no fluorescence was observed on the magnetic beads during fluorescent imaging, it indicates the bacterial concentration in the sample to be too low for it to have bound to the magnetic beads and hence no detection was possible. To detect bacterial concentration less than 10(5) CFU/ml in the sample, an additional step was required for detection. The magnetic bead complex was added to the LST-MUG (lauryl sulfate tryptose-4-methylumbelliferyl-β-D-glucuronide), a signaling reporter. The E. coli O104:H4 grows in LST-MUG and releases β-glucuronidase enzyme. This enzyme cleaves the MUG substrate that produces 4-methylumbelliferone, a highly fluorescent species. This fluorescence was detected using a spectrofluorometer. The emission peak in the fluorescent spectrum was found to be at 450 nm. The lower and upper detection range for this LST-MUG assay was found to be 2.05×10(5)-4.09×10(8) CFU/ml. The results for the LST-MUG assay for concentrations below 10(5) CFU/ml were ascertained in 8h. The advantages of this technique include the specific detection of bacteria without an enrichment step and

Preparation of acetaminophen capsules containing beads prepared by hot-melt direct blend coating.

Science.gov (United States)

Pham, Loan; Christensen, John M

2014-02-01

Twelve hydrophobic coating agents were assessed for their effects on drug release after coating sugar cores by a flexible hot-melt coating method using direct blending. Drug-containing pellets were also produced and used as cores. The cores were coated with single or double wax layers containing acetaminophen (APAP). The harder the wax, the slower the resultant drug releases from single-coated beads. Wax coating can be deposited on cores up to 28% of the beads final weight and reaching 58% with wax and drug. Carnauba-coated beads dissolved in approximately 6 h releasing 80% of the loaded drug. Applying another wax layer extended drug release over 20 h, while still delivering 80% of the loaded drug. When drug-containing pellets (33-58% drug loading) were used as cores, double wax-coated pellets exhibited a near zero-order drug release for 16 h, releasing 80% of the loaded drug delivering 18 mg/h. The simple process of hot-melt coating by direct blending of pellet-containing drug-coated formulations provides excellent options for immediate and sustained release formulations when higher lipid coating or drug loading is warranted. Predicted plasma drug concentration time profiles using convolution and in vitro drug release properties of the beads were performed for optimal formulations.

PCR-free detection of genetically modified organisms using magnetic capture technology and fluorescence cross-correlation spectroscopy.

Directory of Open Access Journals (Sweden)

Xiaoming Zhou

2009-11-01

Full Text Available The safety of genetically modified organisms (GMOs has attracted much attention recently. Polymerase chain reaction (PCR amplification is a common method used in the identification of GMOs. However, a major disadvantage of PCR is the potential amplification of non-target DNA, causing false-positive identification. Thus, there remains a need for a simple, reliable and ultrasensitive method to identify and quantify GMO in crops. This report is to introduce a magnetic bead-based PCR-free method for rapid detection of GMOs using dual-color fluorescence cross-correlation spectroscopy (FCCS. The cauliflower mosaic virus 35S (CaMV35S promoter commonly used in transgenic products was targeted. CaMV35S target was captured by a biotin-labeled nucleic acid probe and then purified using streptavidin-coated magnetic beads through biotin-streptavidin linkage. The purified target DNA fragment was hybridized with two nucleic acid probes labeled respectively by Rhodamine Green and Cy5 dyes. Finally, FCCS was used to detect and quantify the target DNA fragment through simultaneously detecting the fluorescence emissions from the two dyes. In our study, GMOs in genetically engineered soybeans and tomatoes were detected, using the magnetic bead-based PCR-free FCCS method. A detection limit of 50 pM GMOs target was achieved and PCR-free detection of GMOs from 5 microg genomic DNA with magnetic capture technology was accomplished. Also, the accuracy of GMO determination by the FCCS method is verified by spectrophotometry at 260 nm using PCR amplified target DNA fragment from GM tomato. The new method is rapid and effective as demonstrated in our experiments and can be easily extended to high-throughput and automatic screening format. We believe that the new magnetic bead-assisted FCCS detection technique will be a useful tool for PCR-free GMOs identification and other specific nucleic acids.

Theoretical study of in-plane response of magnetic field sensor to magnetic beads magnetized by the sensor self-field

DEFF Research Database (Denmark)

Hansen, Troels Borum Grave; Damsgaard, Christian Danvad; Dalslet, Bjarke Thomas

2010-01-01

We present a theoretical study of the spatially averaged in-plane magnetic field on square and rectangular magnetic field sensors from a single magnetic bead, a monolayer of magnetic beads, and a half-space filled with magnetic beads being magnetized by the magnetic self-field due to the applied...... bias current through the sensor. The analysis of the single bead response shows that beads always contribute positively to the average magnetic field as opposed to the case for an applied homogeneous magnetic field where the sign of the signal depends on the bead position. General expressions...... and analytical approximations are derived for the sensor response to beads as function of the bead distribution, the bias current, the geometry and size of the sensor, and the bead characteristics. Consequences for the sensor design are exemplified and it is described how the contribution from the self...

Magnetic Bead Based Immunoassay for Autonomous Detection of Toxins

Energy Technology Data Exchange (ETDEWEB)

Kwon, Y; Hara, C A; Knize, M G; Hwang, M H; Venkatesteswaran, K S; Wheeler, E K; Bell, P M; Renzi, R F; Fruetel, J A; Bailey, C G

2008-05-01

As a step towards toward the development of a rapid, reliable analyzer for bioagents in the environment, we are developing an automated system for the simultaneous detection of a group of select agents and toxins. To detect toxins, we modified and automated an antibody-based approach previously developed for manual medical diagnostics that uses fluorescent eTag{trademark} reporter molecules and is suitable for highly multiplexed assays. Detection is based on two antibodies binding simultaneously to a single antigen, one of which is labeled with biotin while the other is conjugated to a fluorescent eTag{trademark} through a cleavable linkage. Aqueous samples are incubated with the mixture of antibodies along with streptavidin-coated magnetic beads coupled to a photo-activatable porphyrin complex. In the presence of antigen, a molecular complex is formed where the cleavable linkage is held in proximity to the photoactivable group. Upon excitation at 680 nm, free radicals are generated, which diffuse and cleave the linkage, releasing the eTags{trademark}. Released eTags{trademark} are analyzed using capillary gel electrophoresis with laser-induced fluorescence detection. Limits of detection for ovalbumin and botulinum toxoid individually were 4 ng/mL (or 80 pg) and 16 ng/mL (or 320 pg), respectively, using the manual assay. In addition, we demonstrated the use of pairs of antibodies from different sources in a single assay to decrease the rate of false positives. Automation of the assay was demonstrated on a flow-through format with higher LODs of 125 ng/mL (or 2.5 ng) each of a mixture of ovalbumin and botulinum toxoid. This versatile assay can be easily modified with the appropriate antibodies to detect a wide range of toxins and other proteins.

On-chip signal amplification of magnetic bead-based immunoassay by aviating magnetic bead chains.

Science.gov (United States)

Jalal, Uddin M; Jin, Gyeong Jun; Eom, Kyu Shik; Kim, Min Ho; Shim, Joon S

2017-11-06

In this work, a Lab-on-a-Chip (LOC) platform is used to electromagnetically actuate magnetic bead chains for an enhanced immunoassay. Custom-made electromagnets generate a magnetic field to form, rotate, lift and lower the magnetic bead chains (MBCs). The cost-effective, disposable LOC platform was made with a polymer substrate and an on-chip electrochemical sensor patterned via the screen-printing process. The movement of the MBCs is controlled to improve the electrochemical signal up to 230% when detecting beta-type human chorionic gonadotropin (β-hCG). Thus, the proposed on-chip MBC-based immunoassay is applicable for rapid, qualitative electrochemical point-of-care (POC) analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Heterogeneous time-resolved electrochemiluminoimmunoassay of thyroid stimulating hormone with magnetic beads at oxide-covered aluminum electrode

Energy Technology Data Exchange (ETDEWEB)

Ala-Kleme, Timo, E-mail: timo.ala-kleme@utu.fi

2017-06-15

The heterogeneous immunoassay of thyroid stimulating hormone (TSH) was detected by the time-resolved cathodic electrochemiluminescence immunoassay (tr-CECLIA) method using magnetic beads as a mobile support. The magnetic beads coated with sandwich type TSH immunoassay were captured with a magnet for washing and detection processes. The time-resolved cathodic electrochemiluminescence (tr-CECL) signal of Tb(III) chelate label was generated by cathodic pulse polarization in the aluminum working electrode and platinum counter electrode system. The detection method causes injection of high energy electrons into the aqueous solution near the aluminum electrode and creates rigid simultaneous oxidative and reductive conditions that excitate the Tb(III) chelate used as a label luminophore in the heterogeneous sandwich type immunoassay of TSH in the surface of the magnetic beads. The limit of detection of the method was about 50 mIU L{sup −1}. The precision of it was noticed to be good; the coefficient variation percentage was realized to be lower than 10 %. Unfortunately the limit of detection is not good enough for determination of analyte levels of very low concentrations for instance TSH in body fluids. The possible application areas of the method are in highly sophisticated micro or nano fluidic detection and sensor systems where the aspiration level of the analyte detection limit is not very high and the mobility and manageability and the large surface area of the magnetic beads can be utilized efficiently in separating, washing, moving, coating and detecting processes. In the case of tr-CECLIA the presented method makes possible to use multipurpose working electrodes instead of disposable ones.

Repetitive Immunosensor with a Fiber-Optic Device and Antibody-Coated Magnetic Beads for Semi-Continuous Monitoring of Escherichia coli O157:H7.

Science.gov (United States)

Taniguchi, Midori; Saito, Hirokazu; Mitsubayashi, Kohji

2017-09-19

A rapid and reproducible fiber-optic immunosensor for Escherichia coli O157:H7 ( E. coli O157:H7) was described. The biosensor consisted of a flow cell, an optical fiber with a thin Ni layer, and a PC linked fluorometer. First, the samples with E. coli O157:H7 were incubated with magnetic beads coated with anti- E. coli O157:H7 antibodies and anti- E. coli O157:H7 antibodies labeled cyanine 5 (Cy5) to make sandwich complexes. Then the Cy5-( E. coli O157:H7)-beads were injected into a flow cell and pulled to the magnetized Ni layer on the optical fiber set in the flow cell. An excitation light (λ = 635 nm) was used to illuminate the optical fiber, and the Cy5 florescent molecules facing the optical fiber were exposed to an evanescent wave from the optical fiber. The 670 nm fluorescent light was measured using a photodiode. Finally, the magnetic intensity of the Ni layer was removed and the Cy5- E. coli O157:H7-beads were washed out for the next immunoassay. E. coli O157:H7, diluted with phosphate buffer (PB), was measured from 1 × 10⁵ to 1 × 10⁷ cells/mL. The total time required for an assay was less than 15 min (except for the pretreatment process) and repeating immunoassay on one optical fiber was made possible.

Evaluation of Antigen-Conjugated Fluorescent Beads to Identify Antigen-Specific B Cells

Directory of Open Access Journals (Sweden)

Isabel Correa

2018-03-01

Full Text Available Selection of single antigen-specific B cells to identify their expressed antibodies is of considerable interest for evaluating human immune responses. Here, we present a method to identify single antibody-expressing cells using antigen-conjugated fluorescent beads. To establish this, we selected Folate Receptor alpha (FRα as a model antigen and a mouse B cell line, expressing both the soluble and the membrane-bound forms of a human/mouse chimeric antibody (MOv18 IgG1 specific for FRα, as test antibody-expressing cells. Beads were conjugated to FRα using streptavidin/avidin-biotin bridges and used to select single cells expressing the membrane-bound form of anti-FRα. Bead-bound cells were single cell-sorted and processed for single cell RNA retrotranscription and PCR to isolate antibody heavy and light chain variable regions. Variable regions were then cloned and expressed as human IgG1/k antibodies. Like the original clone, engineered antibodies from single cells recognized native FRα. To evaluate whether antigen-coated beads could identify specific antibody-expressing cells in mixed immune cell populations, human peripheral blood mononuclear cells (PBMCs were spiked with test antibody-expressing cells. Antigen-specific cells could comprise up to 75% of cells selected with antigen-conjugated beads when the frequency of the antigen-positive cells was 1:100 or higher. In PBMC pools, beads conjugated to recombinant antigens FRα and HER2 bound antigen-specific anti-FRα MOv18 and anti-HER2 Trastuzumab antibody-expressing cells, respectively. From melanoma patient-derived B cells selected with melanoma cell line-derived protein-coated fluorescent beads, we generated a monoclonal antibody that recognized melanoma antigen-coated beads. This approach may be further developed to facilitate analysis of B cells and their antibody profiles at the single cell level and to help unravel humoral immune repertoires.

Evaluation of Antigen-Conjugated Fluorescent Beads to Identify Antigen-Specific B Cells.

Science.gov (United States)

Correa, Isabel; Ilieva, Kristina M; Crescioli, Silvia; Lombardi, Sara; Figini, Mariangela; Cheung, Anthony; Spicer, James F; Tutt, Andrew N J; Nestle, Frank O; Karagiannis, Panagiotis; Lacy, Katie E; Karagiannis, Sophia N

2018-01-01

Selection of single antigen-specific B cells to identify their expressed antibodies is of considerable interest for evaluating human immune responses. Here, we present a method to identify single antibody-expressing cells using antigen-conjugated fluorescent beads. To establish this, we selected Folate Receptor alpha (FRα) as a model antigen and a mouse B cell line, expressing both the soluble and the membrane-bound forms of a human/mouse chimeric antibody (MOv18 IgG1) specific for FRα, as test antibody-expressing cells. Beads were conjugated to FRα using streptavidin/avidin-biotin bridges and used to select single cells expressing the membrane-bound form of anti-FRα. Bead-bound cells were single cell-sorted and processed for single cell RNA retrotranscription and PCR to isolate antibody heavy and light chain variable regions. Variable regions were then cloned and expressed as human IgG1/k antibodies. Like the original clone, engineered antibodies from single cells recognized native FRα. To evaluate whether antigen-coated beads could identify specific antibody-expressing cells in mixed immune cell populations, human peripheral blood mononuclear cells (PBMCs) were spiked with test antibody-expressing cells. Antigen-specific cells could comprise up to 75% of cells selected with antigen-conjugated beads when the frequency of the antigen-positive cells was 1:100 or higher. In PBMC pools, beads conjugated to recombinant antigens FRα and HER2 bound antigen-specific anti-FRα MOv18 and anti-HER2 Trastuzumab antibody-expressing cells, respectively. From melanoma patient-derived B cells selected with melanoma cell line-derived protein-coated fluorescent beads, we generated a monoclonal antibody that recognized melanoma antigen-coated beads. This approach may be further developed to facilitate analysis of B cells and their antibody profiles at the single cell level and to help unravel humoral immune repertoires.

Evaluation of Antigen-Conjugated Fluorescent Beads to Identify Antigen-Specific B Cells

Science.gov (United States)

Correa, Isabel; Ilieva, Kristina M.; Crescioli, Silvia; Lombardi, Sara; Figini, Mariangela; Cheung, Anthony; Spicer, James F.; Tutt, Andrew N. J.; Nestle, Frank O.; Karagiannis, Panagiotis; Lacy, Katie E.; Karagiannis, Sophia N.

2018-01-01

Selection of single antigen-specific B cells to identify their expressed antibodies is of considerable interest for evaluating human immune responses. Here, we present a method to identify single antibody-expressing cells using antigen-conjugated fluorescent beads. To establish this, we selected Folate Receptor alpha (FRα) as a model antigen and a mouse B cell line, expressing both the soluble and the membrane-bound forms of a human/mouse chimeric antibody (MOv18 IgG1) specific for FRα, as test antibody-expressing cells. Beads were conjugated to FRα using streptavidin/avidin-biotin bridges and used to select single cells expressing the membrane-bound form of anti-FRα. Bead-bound cells were single cell-sorted and processed for single cell RNA retrotranscription and PCR to isolate antibody heavy and light chain variable regions. Variable regions were then cloned and expressed as human IgG1/k antibodies. Like the original clone, engineered antibodies from single cells recognized native FRα. To evaluate whether antigen-coated beads could identify specific antibody-expressing cells in mixed immune cell populations, human peripheral blood mononuclear cells (PBMCs) were spiked with test antibody-expressing cells. Antigen-specific cells could comprise up to 75% of cells selected with antigen-conjugated beads when the frequency of the antigen-positive cells was 1:100 or higher. In PBMC pools, beads conjugated to recombinant antigens FRα and HER2 bound antigen-specific anti-FRα MOv18 and anti-HER2 Trastuzumab antibody-expressing cells, respectively. From melanoma patient-derived B cells selected with melanoma cell line-derived protein-coated fluorescent beads, we generated a monoclonal antibody that recognized melanoma antigen-coated beads. This approach may be further developed to facilitate analysis of B cells and their antibody profiles at the single cell level and to help unravel humoral immune repertoires. PMID:29628923

A polyamidoamine dendrimer-streptavidin supramolecular architecture for biosensor development.

Science.gov (United States)

Soda, N; Arotiba, O A

2017-12-01

A novel polyamidoamine dendrimer-streptavidin supramolecular architecture suitable as a versatile platform for biosensor development is reported. The dendrimer was electrodeposited on a glassy carbon electrode via cyclic voltammetry. The dendrimer electrode was further modified with streptavidin by electrostatic attraction upon drop coating. The platform i.e. the dendrimer-streptavidin modified electrode was electrochemically interrogated in phosphate buffer, ferrocyanide and H 2 O 2 . The dendrimer-streptavidin platform was used in the preparation of a simple DNA biosensor as a proof of concept. The supramolecular architecture of dendrimer-streptavidin was stable, electroactive and thus lends itself as a versatile immobilisation layer for any biotinylated bioreceptors in biosensor development. Copyright © 2017 Elsevier B.V. All rights reserved.

Bead Capture on Magnetic Sensors in a Microfluidic System

DEFF Research Database (Denmark)

Østerberg, Frederik Westergaard; Dalslet, Bjarke Thomas; Damsgaard, Christian Danvad

2009-01-01

The accumulation of magnetic beads by gravitational sedimentation and magnetic capture on a planar Hall-effect sensor integrated in a microfluidic channel is studied systematically as a function of the bead concentration, the fluid flow rate, and the sensor bias current. It is demonstrated...... that the sedimentation flux is proportional to the bead concentration and has a power law relation to the fluid flow rate. The mechanisms for the bead accumulation are investigated and it is found that gravitational sedimentation dominates the bead accumulation, whereas the stability of the sedimented beads against...

Label-acquired magnetorotation for biosensing: An asynchronous rotation assay

International Nuclear Information System (INIS)

Hecht, Ariel; Kinnunen, Paivo; McNaughton, Brandon; Kopelman, Raoul

2011-01-01

This paper presents a novel application of magnetic particles for biosensing, called label-acquired magnetorotation (LAM). This method is based on a combination of the traditional sandwich assay format with the asynchronous magnetic bead rotation (AMBR) method. In label-acquired magnetorotation, an analyte facilitates the binding of a magnetic label bead to a nonmagnetic solid phase sphere, forming a sandwich complex. The sandwich complex is then placed in a rotating magnetic field, where the rotational frequency of the sandwich complex is a function of the amount of analyte attached to the surface of the sphere. Here, we use streptavidin-coated beads and biotin-coated particles as analyte mimics, to be replaced by proteins and other biological targets in future work. We show this sensing method to have a dynamic range of two orders of magnitude.

Cultivation of human dermal fibroblasts and epidermal keratinocytes on keratin-coated silica bead substrates.

Science.gov (United States)

Tan, Bee Yi; Nguyen, Luong T H; Kim, Hyo-Sop; Kim, Jae-Ho; Ng, Kee Woei

2017-10-01

Human hair keratin is promising as a bioactive material platform for various biomedical applications. To explore its versatility further, human hair keratin was coated onto monolayers of silica beads to produce film-like substrates. This combination was hypothesized to provide a synergistic effect in improving the biochemical properties of the resultant composite. Atomic force microscopy analysis showed uniform coatings of keratin on the silica beads with a slight increase in the resulting surface roughness. Keratin-coated silica beads had higher surface energy and relatively lower negative charge than those of bare silica beads. To investigate cell response, human dermal fibroblasts (HDFs), and human epidermal keratinocytes (HEKs) were cultured on the substrates over 4 days. Results showed that keratin coatings significantly enhanced the metabolic activity of HDFs and encouraged cell spreading but did not exert any significant effects on HEKs. HDF expression of collagen I was significantly more intense on the keratin-coated compared to the bare silica substrates. Furthermore, HDF secretion of various cytokines suggested that keratin coatings triggered active cell responses related to wound healing. Collectively, our study demonstrated that human hair keratin-coated silica bead monolayers have the potential to modulate HDF behavior in culture and may be exploited further. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2789-2798, 2017. © 2017 Wiley Periodicals, Inc.

A High-Throughput SU-8Microfluidic Magnetic Bead Separator

DEFF Research Database (Denmark)

Bu, Minqiang; Christensen, T. B.; Smistrup, Kristian

2007-01-01

We present a novel microfluidic magnetic bead separator based on SU-8 fabrication technique for high through-put applications. The experimental results show that magnetic beads can be captured at an efficiency of 91 % and 54 % at flow rates of 1 mL/min and 4 mL/min, respectively. Integration...... of soft magnetic elements in the chip leads to a slightly higher capturing efficiency and a more uniform distribution of captured beads over the separation chamber than the system without soft magnetic elements....

Removal of organic dyes by magnetic alginate beads.

Science.gov (United States)

Rocher, Vincent; Siaugue, Jean-Michel; Cabuil, Valérie; Bee, Agnès

2008-02-01

This study deals with the development of a clean and safe process for water pollution remediation. We have synthesized a magnetic adsorbent in order to develop a solid-phase extraction process assisted by a magnetic field. To follow an 'ecoconception' approach, magnetic beads containing magnetic nanoparticles and activated carbon are prepared with a biopolymer extracted from algae, sodium alginate. The use of renewable bioresources of low cost and those disposable in large amount allows the development of a product with a low impact on the environment. The adsorption properties of activated carbon and magnetic properties of iron oxide nanoparticles are combined to produce an interesting magnetic composite. Synthesis and characterization of the magnetic beads have been reported. Their adsorption capacity was investigated by measuring the removal of two dyes (methylene blue and methyl orange) of different charges from aqueous solutions. The efficiency of the beads has been compared with that of non-encapsulated activated carbon. The effects of initial dye concentration, pH and calcium content of the beads have been studied. Adsorption kinetics experiments have been carried out and the data have been well fitted by a pseudo-second-order equation.

Magnetic measurements of suspended functionalised ferromagnetic beads under DC applied fields

International Nuclear Information System (INIS)

De Los Santos V, Luis; Llandro, Justin; Lee, Dongwook; Mitrelias, Thanos; Palfreyman, Justin J.; Hayward, Thomas J.; Cooper, Jos; Bland, J.A.C.; Barnes, Crispin H.W.; Arroyo C, Juan L.; Lees, Martin

2009-01-01

In this work, a simple technique to obtain the hysteresis loops of magnetic beads (Spherotech Inc.) in liquid suspension is presented. The magnetic measurements were taken in a DC Magnetic Property Measurement System (MPMS-SQUID sensor). Samples were based on ferromagnetic beads (surface-functionalized NH 2 , mean diameter 4.32 μm) prepared in three conditions: dry, suspended in sucrose solution and in suspension after functionalization with fluorophore. Special small containers (1.3 cm long) made of non magnetic plastic were designed to hold the beads in liquid. The results indicate that the bead's remnant magnetization is half of the value at maximum applied field in all cases. However, due to the additional degrees of rotational freedom, beads suspended in a liquid do not present coercivity. The use of ferromagnetic beads and magnetic elements of different architectures for applications in bioassays is also discussed.

Planar Hall effect sensor bridge geometries optimized for magnetic bead detection

DEFF Research Database (Denmark)

Østerberg, Frederik Westergaard; Rizzi, Giovanni; Henriksen, Anders Dahl

2014-01-01

Novel designs of planar Hall effect bridge sensors optimized for magnetic bead detection are presented and characterized. By constructing the sensor geometries appropriately, the sensors can be tailored to be sensitive to an external magnetic field, the magnetic field due to beads being magnetized...... by the sensor self-field or a combination thereof. The sensors can be made nominally insensitive to small external magnetic fields, while being maximally sensitive to magnetic beads, magnetized by the sensor self-field. Thus, the sensor designs can be tailored towards specific applications with minimal...... of the dynamic magnetic response of suspensions of magnetic beads with a nominal diameter of 80 nm are performed. Furthermore, a method to amplify the signal by appropriate combinations of multiple sensor segments is demonstrated....

Effects of Magnetic Particles Entrance Arrangements on Mixing Efficiency of a Magnetic Bead Micromixer

Institute of Scientific and Technical Information of China (English)

Reza Kamali; Seyed Alireza Shekoohi; Alireza Binesh

2014-01-01

In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter the micromixer by fluid flows and are actuated by an alternating magnetic field normal to the main flow. An important feature of micromixer which is not considered before by researchers is the particle entrance arrangement into the micromixer. This parameter could effectively affect the micromixer efficiency. There are two general micro magnetic particle entrance arrangements in magnetic bead micromixers: determined position entrance and random position entrance. In the case of determined position entrances, micro magnetic particles enter the micromixer at specific positions of entrance cross section. However, in a random position entrance,particles enter the microchannel with no order. In this study mixing efficiencies of identical magnetic bead micromixers which only differ in particle entrance arrangement are numerically investigated and compared.The results reported in this paper illustrate that the prepared computer code can be one of the most powerful and beneficial tools for the magnetic bead micromixer performance analysis. In addition, the results show that some features of the magnetic bead micromixer are strongly affected by the entrance arrangement of the particles.

The isolation and characterization of twelve novel microsatellite loci ...

African Journals Online (AJOL)

hp

2013-12-18

Dec 18, 2013 ... MboI adapter2 (5'-GTCAAGAATTCGGTACCGTCGAC-3') were ligated to the digested products using T4 DNA ligase. The ligated product was hybridized with biotin-labeled sequence repeats (SSR) probes. (GT)15, (CT)15, and the hybrid mixture was incubated with magnetic beads coated with streptavidin.

Theoretical study of in-plane response of magnetic field sensor to magnetic beads in an in-plane homogeneous field

DEFF Research Database (Denmark)

Damsgaard, Christian Danvad; Hansen, Mikkel Fougt

2008-01-01

We present a systematic theoretical study of the average in-plane magnetic field on square and rectangular magnetic field sensors from a single magnetic bead and a monolayer of magnetic beads magnetized by an in-plane externally applied homogeneous magnetic field. General theoretical expressions...... are derived such that the sensor response and its dependence on the sensor size, spacer layer thickness, bead diameter, and bead susceptibility can easily be evaluated. The average magnetic field from a single bead close to the sensor shows a strong dependence on the position of the bead and a change of sign...... when the bead passes the edge of the sensor in the direction of the applied field. Analytical approximations are derived for the average field from a homogeneous monolayer of beads for beads much smaller than the sensor dimension and for a bead size chosen to minimize the position sensitivity...

An approach to implement virtual channels for flowing magnetic beads

International Nuclear Information System (INIS)

Tang, Shih-Hao; Chiang, Hung-Wei; Hsieh, Min-Chien; Chang, Yen-Di; Yeh, Po-Fan; Tsai, Jui-che; Shieh, Wung-Yang

2014-01-01

This work demonstrates the feasibility of a novel microfluidic system with virtual channels formed by ‘walls’ of magnetic fields, including collecting channels, transporting channels and function channels. The channels are defined by the nickel patterns. With its own ferromagnetism, nickel can be magnetized using an external magnetic field; the nickel structures then generate magnetic fields that can either guide or trap magnetic beads. A glass substrate is sandwiched between the liquid containing magnetic beads and the chip with nickel structures, preventing the liquid from directly contacting the nickel. In this work, collecting channels, transporting channels and function channels are displayed sequentially. In the collecting channel portion, channels with different shapes are compared. Next, in the transporting channel portion we demonstrate I-, S- and Y-shaped channels can steer magnetic beads smoothly. Finally, in the function channel portion, a switchable trapping channel implemented with a bistable mechanism performs the passing and blocking of a magnetic bead. (paper)

Echicetin coated polystyrene beads: a novel tool to investigate GPIb-specific platelet activation and aggregation.

Directory of Open Access Journals (Sweden)

Alexey Navdaev

Full Text Available von Willebrand factor/ristocetin (vWF/R induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways.

Echicetin Coated Polystyrene Beads: A Novel Tool to Investigate GPIb-Specific Platelet Activation and Aggregation

Science.gov (United States)

Petunin, Alexey; Clemetson, Kenneth J.; Gambaryan, Stepan; Walter, Ulrich

2014-01-01

von Willebrand factor/ristocetin (vWF/R) induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways. PMID:24705415

Automated solid-phase subcloning based on beads brought into proximity by magnetic force.

Science.gov (United States)

Hudson, Elton P; Nikoshkov, Andrej; Uhlen, Mathias; Rockberg, Johan

2012-01-01

In the fields of proteomics, metabolic engineering and synthetic biology there is a need for high-throughput and reliable cloning methods to facilitate construction of expression vectors and genetic pathways. Here, we describe a new approach for solid-phase cloning in which both the vector and the gene are immobilized to separate paramagnetic beads and brought into proximity by magnetic force. Ligation events were directly evaluated using fluorescent-based microscopy and flow cytometry. The highest ligation efficiencies were obtained when gene- and vector-coated beads were brought into close contact by application of a magnet during the ligation step. An automated procedure was developed using a laboratory workstation to transfer genes into various expression vectors and more than 95% correct clones were obtained in a number of various applications. The method presented here is suitable for efficient subcloning in an automated manner to rapidly generate a large number of gene constructs in various vectors intended for high throughput applications.

Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads

Energy Technology Data Exchange (ETDEWEB)

Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim [Institute of Bioelectronics (ICS-8/PGI-8), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

2015-04-15

As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm{sup 2}, a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle’s position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

Towards a programmable magnetic bead microarray in a microfluidic channel

DEFF Research Database (Denmark)

Smistrup, Kristian; Bruus, Henrik; Hansen, Mikkel Fougt

2007-01-01

to use larger currents and obtain forces of longer range than from thin current lines at a given power limit. Guiding of magnetic beads in the hybrid magnetic separator and the construction of a programmable microarray of magnetic beads in the microfluidic channel by hydrodynamic focusing is presented....

Bead Capture and Release on a Magnetic Sensor in a Microfluidic System

DEFF Research Database (Denmark)

Dalslet, Bjarke Thomas; Damsgaard, Christian Danvad; Freitas, S.C.

Planar Hall effect magnetic sensors for detection of biological agents using surface treated magnetic beads are integrated with a fluid injection system. The response of the sensors is used to evaluate bead capture rates for different bead concentrations c and fluid flow rates Q, and to monitor...... subsequent removal of the beads. It is found that the capture rate scales directly with c and that it depends linearly on Q. At low Q the capture rate is only partially due to gravitational sedimentation of beads. At higher Q an additional term proportional to Q becomes important, which is attributed...... to capture of beads by the magnetic fields near the sensor. It is shown that beads can be washed off the sensor surface....

On-chip measurement of the Brownian relaxation frequency of magnetic beads using magnetic tunneling junctions

DEFF Research Database (Denmark)

Donolato, M.; Sogne, E.; Dalslet, Bjarke Thomas

2011-01-01

We demonstrate the detection of the Brownian relaxation frequency of 250 nm diameter magnetic beads using a lab-on-chip platform based on current lines for exciting the beads with alternating magnetic fields and highly sensitive magnetic tunnel junction (MTJ) sensors with a superparamagnetic free...

Development of a magnetic bead-based method for the collection of circulating extracellular vesicles.

Science.gov (United States)

Shih, Chun-Liang; Chong, Kowit-Yu; Hsu, Shih-Che; Chien, Hsin-Jung; Ma, Ching-Ting; Chang, John Wen-Cheng; Yu, Chia-Jung; Chiou, Chiuan-Chian

2016-01-25

Cells release different types of extracellular vesicles (EVs). These EVs contain biomolecules, including proteins and nucleic acids, from their parent cells, which can be useful for diagnostic applications. The aim of this study was to develop a convenient procedure to collect circulating EVs with detectable mRNA or other biomolecules. Magnetic beads coated with annexin A5 (ANX-beads), which bound to phosphatidylserine moieties on the surfaces of most EVs, were tested for their ability to capture induced apoptotic bodies in vitro and other phosphatidylserine-presenting vesicles in body fluids. Our results show that up to 60% of induced apoptotic bodies could be captured by the ANX-beads. The vesicles captured from cultured media or plasma contained amplifiable RNA. Suitable blood samples for EV collection included EDTA-plasma and serum but not heparin-plasma. In addition, EVs in plasma were labile to freeze-and-thaw cycles. In rodents xenografted with human cancer cells, tumor-derived mRNA could be detected in EVs captured from serum samples. Active proteins could be detected in EVs captured from ascites but not from plasma. In conclusion, we have developed a magnetic bead-based procedure for the collection of EVs from body fluids and proved that captured EVs contain biomolecules from their parent cells, and therefore have great potential for disease diagnosis. Copyright © 2015 Elsevier B.V. All rights reserved.

A planar conducting microstructure to guide and confine magnetic beads to a sensing zone

KAUST Repository

Gooneratne, Chinthaka Pasan

2011-08-01

A novel planar conducting microstructure is proposed to transport and confine magnetic micro/nano beads to a sensing zone. Manipulation and concentration of magnetic beads are achieved by employing square-shaped conducting micro-loops, with a few hundred nano-meters in thickness, arranged in a unique fashion. These microstructures are designed to produce high magnetic field gradients which are directly proportional to the force applied to manipulate the magnetic beads. Furthermore, the size of the microstructures allows greater maneuverability and control of magnetic beads than what could be achieved by permanent magnets. The aim of the microstructures is to guide magnetic beads from a large area and confine them to a smaller area where for example quantification would take place. Experiments were performed with different concentrations of 2 μm diameter magnetic beads. Experimental results showed that magnetic beads could be successfully guided and confined to the sensing zone. © 2011 Elsevier B.V. All rights reserved.

Preparation and Characterization of Super-paramagnetic Nano-beads for DNA Isolation

Institute of Scientific and Technical Information of China (English)

Xin XIE; Xu ZHANG; Bing Bin YU; wei Yang FE

2004-01-01

Unique coupling reagent, bis-(2-hydroxyethyl methacrylate) phosphate was used to prepare coated and functionalized superparamagnetic nanobeads, leading to a simple, effective method for coating the nanobeads. With this method, the thickness of the coating layer and the functional group contents on the nano-beads could be controlled by changing the quantity of the coated monomers. The nanobeads were characterized by means of transmission electron microscopy (TEM) and Fourier transformation infrared spectroscopy (FTIR). The carboxyl-modified magnetic nano-beads were employed to streamline the protocol of isolation of genomic DNA from the human whole blood.

Magnetization of large polystyrene peptide beads for capturing and expanding cancer cells

International Nuclear Information System (INIS)

Marik, Jan; Lau, D.H.; Song Aimin; Wang Xiaobing; Liu Ruiwu; Lam, K.S.

2003-01-01

A method is described for preparation of large magnetic polystyrene beads coupled with peptide ligands for surface receptors of lung cancer cells. We have demonstrated the feasibility of using these magnetic peptide beads for capturing and enriching lung cancer cells spiked into blood. These magnetic peptide beads potentially can be used to efficiently isolate cancer cells from body fluids

Characterization of Antigen-Specific B Cells Using Nominal Antigen-Coated Flow-Beads

Science.gov (United States)

Akl, Ahmed; Lepetit, Maud; Crochette, Romain; Giral, Magali; Lepourry, Julie; Pallier, Annaick; Castagnet, Stéphanie; Dugast, Emilie; Guillot-Gueguen, Cécile; Jacq-Foucher, Marylène; Saulquin, Xavier; Cesbron, Anne; Laplaud, David; Nicot, Arnaud; Brouard, Sophie; Soulillou, Jean-Paul

2013-01-01

In order to characterize the reactivity of B cells against nominal antigens, a method based on the coupling of antigens onto the surface of fluorescent core polystyrene beads was developed. We first demonstrate that murine B cells with a human MOG-specific BCR are able to interact with MOG-coated beads and do not recognize beads coated with human albumin or pp65. B cells purified from human healthy volunteer blood or immunized individuals were tested for their ability to interact with various nominal antigens, including viral, vaccine, self and alloantigens, chosen for their usefulness in studying a variety of pathological processes. A substantial amount of B cells binding self-antigen MOG-coated beads can be detected in normal blood. Furthermore, greater frequencies of B cell against anti-Tetanic Toxin or anti-EBNA1 were observed in primed individuals. This method can reveal increased frequencies of anti-HLA committed B cells in patients with circulating anti-HLA antibodies compared to unsensitized patients and normal individuals. Of interest, those specific CD19 cells were preferentially identified within CD27−IgD+ (i-e naïve) subset. These observations suggest that a broad range of medical situations could benefit from a tool that allows the detection, the quantification and the characterization of antigen-specific blood B cells. PMID:24386360

Effects of Magnetic Particles Entrance Arrange-ments on Mixing Efficiency of a Magnetic Bead Micromixer

Institute of Scientific and Technical Information of China (English)

Reza Kamali∗; Seyed Alireza Shekoohi; Alireza Binesh

2014-01-01

In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter the micromixer by fluid flows and are actuated by an alternating magnetic field normal to the main flow. An important feature of micromixer which is not considered before by researchers is the particle entrance arrangement into the micromixer. This parameter could effectively affect the micromixer efficiency. There are two general micro magnetic particle entrance arrangements in magnetic bead micromixers: determined position entrance and random position entrance. In the case of determined position entrances, micro magnetic particles enter the micromixer at specific positions of entrance cross section. However, in a random position entrance, particles enter the microchannel with no order. In this study mixing efficiencies of identical magnetic bead micromixers which only differ in particle entrance arrangement are numerically investigated and compared. The results reported in this paper illustrate that the prepared computer code can be one of the most powerful and beneficial tools for the magnetic bead micromixer performance analysis. In addition, the results show that some features of the magnetic bead micromixer are strongly affected by the entrance arrangement of the particles.

Binding assays with streptavidin-functionalized superparamagnetic nanoparticles and biotinylated analytes using fluxgate magnetorelaxometry

International Nuclear Information System (INIS)

Heim, Erik; Ludwig, Frank; Schilling, Meinhard

2009-01-01

Binding assays based on the magnetorelaxation of superparamagnetic nanoparticles as markers are presented utilizing a differential fluxgate system. As ligand and receptor, streptavidin and biotin, respectively, are used. Superparamagnetic nanoparticles are functionalized with streptavidin and bound to two types of biotinylated analytes: agarose beads and bovine serum (BSA) proteins. The size difference of the two analytes causes a different progress of the reaction. As a consequence, the analysis of the relaxation signal is carried out dissimilarly for the two analytes. In addition, we studied the reaction kinetics of the two kinds of analytes with the fluxgate system.

Aptamer-Modified Magnetic Beads in Biosensing

Science.gov (United States)

Scheper, Thomas; Walter, Johanna-Gabriela

2018-01-01

Magnetic beads (MBs) are versatile tools for the purification, detection, and quantitative analysis of analytes from complex matrices. The superparamagnetic property of magnetic beads qualifies them for various analytical applications. To provide specificity, MBs can be decorated with ligands like aptamers, antibodies and peptides. In this context, aptamers are emerging as particular promising ligands due to a number of advantages. Most importantly, the chemical synthesis of aptamers enables straightforward and controlled chemical modification with linker molecules and dyes. Moreover, aptamers facilitate novel sensing strategies based on their oligonucleotide nature that cannot be realized with conventional peptide-based ligands. Due to these benefits, the combination of aptamers and MBs was already used in various analytical applications which are summarized in this article. PMID:29601533

Comparison between simulation and experimentally observed interactions between two magnetic beads in a fluidic system

Energy Technology Data Exchange (ETDEWEB)

Oduwole, Olayinka, E-mail: olayinka.oduwole@eng.ox.ac.uk; Grob, David Tim, E-mail: tim.grob@eng.ox.ac.uk; Sheard, Steve, E-mail: steve.sheard@eng.ox.ac.uk

2016-06-01

Continuous flow separation of magnetic particles within a microfluidic device could lead to improved performance of magnetic bead-based assays but the undesirable formation of bead clusters reduces its efficiency; this efficiency refers to the ability to separate bound magnetic beads from a mixture of particles. Such agglomerates are formed due to magnetic binding forces while hydrodynamic interactions strongly influence the particles' movement. This paper presents a model for interactions between a pair of equal sized super-paramagnetic beads suspended in water within a uniform magnetic field. To the best of our knowledge, we present for the first time a comparison between simulated trajectories and the beads' movement captured on video; the beads were suspended in a stationary fluid placed within a uniform magnetic field. In conclusion, the model is a good approximation for beads interacting with their nearest neighbours and is able to predict the trajectory pattern of these particles in a magnetic bead-based assay. Predicting the magnetically induced interaction of nearby beads will help in determining the density of beads in an assay and in avoiding agglomeration over a fixed time duration. - Highlights: • We modelled the interactions between a pair of super-paramagnetic beads suspended in water within a uniform magnetic field. • We tracked the movement of the bead pair and captured it on video. • We compared the numerical results with the video data and achieved a good agreement. • We predicted the agglomeration time as a function of the separation distance.

Magnetic composite beads for sorption of cesium ions from aqueous streams

International Nuclear Information System (INIS)

Shinde, Rakesh N.; Pandey, A.K.; Acharya, R.; Rajurkar, N.S.

2014-01-01

Magnetic separation of metal ions is one of the promising methods due to simple, fast, efficient and cost effective technology. Highly selective magnetic sorbents can be designed by immobilizing functional groups in magnetic carrier which binds to the target specific ions. In the present work chitosan-(3-aminopropyl) triethoxysilane (APTS)- copperferrocyanide (CFC) composite beads have been synthesized for sorption of 137 Cs ions from aqueous streams. Physical characterization of the best resulted polymer beads was carried out by SEM-EDX and VSM technique. Sorption of Cs ions in the various magnetic polymer beads were studied in different aqueous condition by 137 Cs (662 KeV) radiotracer assay

Polymerase chain reaction system using magnetic beads for analyzing a sample that includes nucleic acid

Science.gov (United States)

Nasarabadi, Shanavaz [Livermore, CA

2011-01-11

A polymerase chain reaction system for analyzing a sample containing nucleic acid includes providing magnetic beads; providing a flow channel having a polymerase chain reaction chamber, a pre polymerase chain reaction magnet position adjacent the polymerase chain reaction chamber, and a post pre polymerase magnet position adjacent the polymerase chain reaction chamber. The nucleic acid is bound to the magnetic beads. The magnetic beads with the nucleic acid flow to the pre polymerase chain reaction magnet position in the flow channel. The magnetic beads and the nucleic acid are washed with ethanol. The nucleic acid in the polymerase chain reaction chamber is amplified. The magnetic beads and the nucleic acid are separated into a waste stream containing the magnetic beads and a post polymerase chain reaction mix containing the nucleic acid. The reaction mix containing the nucleic acid flows to an analysis unit in the channel for analysis.

Superparamagnetic beads in rotating magnetic fields: microfluidic experiments

NARCIS (Netherlands)

Den Toonder, J.M.J.; Bokdam, M.

2008-01-01

The effect of the Mason number, ratio of viscous and magnetic force, on suspended superparamagnetic micro sized beads was investigated experimentally. Microfluidic experiments were performed in a set-up that generates a rotating homogeneous magnetic field. In the presence of a magnetic field, the

A more sensitive, efficient and ISO 17025 validated Magnetic Capture real time PCR method for the detection of archetypal Toxoplasma gondii strains in meat.

Science.gov (United States)

Gisbert Algaba, Ignacio; Geerts, Manon; Jennes, Malgorzata; Coucke, Wim; Opsteegh, Marieke; Cox, Eric; Dorny, Pierre; Dierick, Katelijne; De Craeye, Stéphane

2017-11-01

Toxoplasma gondii is a globally prevalent, zoonotic parasite of major importance to public health. Various indirect and direct methods can be used for the diagnosis of toxoplasmosis. Whereas serological tests are useful to prove contact with the parasite has occurred, the actual presence of the parasite in the tissues of a seropositive animal is not demonstrated. For this, a bioassay is still the reference method. As an alternative, various PCR methods have been developed, but due to the limited amount of sample that can be tested, combined with a low tissue cyst density, those have proved to be insufficiently sensitive. A major improvement of the sensitivity was achieved with magnetic capture-based DNA extraction. By combining the hybridization of specific, biotinylated probes with the capture of those probes with streptavidin-coated paramagnetic beads, T. gondii DNA can selectively be "fished out" from a large volume of meat lysate. Still, several studies showed an insufficient sensitivity compared with the mouse bioassay. Here we present a method that is more sensitive (99% limit of detection: 65.4 tachyzoites per 100g of meat), economical and reliable (ISO 17025 validated) by adding a non-competitive PCR inhibition control (co-capture of cellular r18S) and making the release of the target DNA from the streptavidin-coated paramagnetic beads UV-dependent. The presented results demonstrate the potential of the modified Magnetic Capture real time PCR as a full alternative to the mouse bioassay for the screening of various types of tissues and meat, with the additional advantage of being quantitative. Copyright © 2017 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

A magnetic bead-based method for concentrating DNA from human urine for downstream detection.

Science.gov (United States)

Bordelon, Hali; Russ, Patricia K; Wright, David W; Haselton, Frederick R

2013-01-01

Due to the presence of PCR inhibitors, PCR cannot be used directly on most clinical samples, including human urine, without pre-treatment. A magnetic bead-based strategy is one potential method to collect biomarkers from urine samples and separate the biomarkers from PCR inhibitors. In this report, a 1 mL urine sample was mixed within the bulb of a transfer pipette containing lyophilized nucleic acid-silica adsorption buffer and silica-coated magnetic beads. After mixing, the sample was transferred from the pipette bulb to a small diameter tube, and captured biomarkers were concentrated using magnetic entrainment of beads through pre-arrayed wash solutions separated by small air gaps. Feasibility was tested using synthetic segments of the 140 bp tuberculosis IS6110 DNA sequence spiked into pooled human urine samples. DNA recovery was evaluated by qPCR. Despite the presence of spiked DNA, no DNA was detectable in unextracted urine samples, presumably due to the presence of PCR inhibitors. However, following extraction with the magnetic bead-based method, we found that ∼50% of spiked TB DNA was recovered from human urine containing roughly 5×10(3) to 5×10(8) copies of IS6110 DNA. In addition, the DNA was concentrated approximately ten-fold into water. The final concentration of DNA in the eluate was 5×10(6), 14×10(6), and 8×10(6) copies/µL for 1, 3, and 5 mL urine samples, respectively. Lyophilized and freshly prepared reagents within the transfer pipette produced similar results, suggesting that long-term storage without refrigeration is possible. DNA recovery increased with the length of the spiked DNA segments from 10±0.9% for a 75 bp DNA sequence to 42±4% for a 100 bp segment and 58±9% for a 140 bp segment. The estimated LOD was 77 copies of DNA/µL of urine. The strategy presented here provides a simple means to achieve high nucleic acid recovery from easily obtained urine samples, which does not contain inhibitors of PCR.

[DNA extraction from decomposed tissue by double-digest and magnetic beads methods].

Science.gov (United States)

Yang, Dian; Liu, Chao; Liu, Hong

2011-12-01

To study the effect of the double-digest and magnetic beads method for DNA extraction from 3 types of decomposed tissues. DNA of cartilages, nails and joint capsule in 91 highly decomposed corpses which had not been extracted by common magnetic beads method, were prepared with the double-digest and magnetic beads methods, and quantified with Quantifiler kit, followed by amplification with Sinofiler kit or Minifiler kit. DNA concentration extracted from the 91 highly decomposed cartilages, nails and joint capsule samples was 0-0.225 ng/microL. Sixty-two samples whose DNA concentration were more than 0.020 ng/microL had obtained 9 or more STR loci successfully. The detection rate was 68.13%. The successful rate of STR genotyping for the 3 types of decomposed tissues can be significantly improved by the double-digest and magnetic beads methods.

Development of the rectal dosage form with silver-coated glass beads for local-action applications in lower sections of the gastrointestinal tract.

Science.gov (United States)

Siczek, Krzysztof; Fichna, Jakub; Zatorski, Hubert; Karolewicz, Bożena; Klimek, Leszek; Owczarek, Artur

2018-03-01

Recent findings indicating the anti-inflammatory action of silver preparations through modulation of the gut microbiota and apoptosis of inflammatory cells predestine silver use in inflammatory bowel disease (IBD). The aim of our study was to validate the possibility of effective silver release from silver-coated glass beads for anti-inflammatory local application in the lower sections of the gastrointestinal (GI) tract. Silver-coated glass beads were prepared using magnetron method. Release of silver from the silver-coated glass bead surface was carried out in BIO-DIS reciprocating cylinder apparatus. Erosion of silver coating and indirect estimation of the silver release dynamics was assessed using scanning electron microscope. Rectal suppositories containing silver-coated glass beads were prepared using five different methods (M1-M5) and X-ray scanned for their composition. The XR microanalysis and the chemical composition analysis evidenced for a rapid (within 30 min) release of nearly 50% of silver from the coating of the glass beads, which remained stable up to 24 h of incubation. The most homogeneous distribution of beads in the entire volume of the suppository was obtained for formulation M5, where the molten base was poured into mold placed in an ice bath, and the beads were added after 10 s. Our study is the first to present the concept of enclosing silver-coated glass beads in the lipophilic suppository base to attenuate inflammation in the lower GI tract and promises efficient treatment with reduced side effects.

Fibroblast receptor for cell-substratum adhesion: studies on the interaction of baby hamster kidney cells with latex beads coated by cold insoluble globulin (plasma fibronectin)

OpenAIRE

1980-01-01

Studies were carried out on the interactions of uncharged latex beads (0.76 micrometer) with baby hamster kidney cells. Binding of beads to the cells occurred if the beads were coated by cold insoluble globulin (CIG) (plasma fibronectin) but not if the beads were coated by bovine albumin. Bovine albumin-coated beads did not bind to the cells even in the presence of excess CIG in the incubation medium. Binding of beads occurred randomly over the entire surfaces of cells in suspension. However,...

Induced movement of the magnetic beads and DNA-based dumbbell in a micro fluidic channel

Science.gov (United States)

Babić, B.; Ghai, R.; Dimitrov, K.

2007-12-01

We have explored controlled movement of magnetic beads and a dumbbell structure composed of DNA, a magnetic and a non-magnetic bead in a micro fluidic channel. Movement of the beads and dumbbells is simulated assuming that a net force is described as a superposition between the magnetic and hydrodynamic drag forces. Trajectories of beads and dumbbells are observed with optical light microscopy. The experimentally measured data show a good agreement with the simulations. This dynamical approach offers the prospect to stretch the DNA within the dumbbell and investigate its conformational changes. Further on, we demonstrate that short sonication can reduce multiple attachments of DNA to the beads.

Effect of patterned micro-magnets on superparamagnetic beads in microchannels

International Nuclear Information System (INIS)

Guo, S S; Deng, Y L; Zhao, L B; Zhao, X-Z; Chan, H L W

2008-01-01

The trapping response of patterned micro-magnets (PMMs) was studied based on the parameters affecting superparamagnetic beads in microfluidic channels. Using replica moulding and electroplating technologies, the PMMs were fabricated on the microchannel bottom, which generated sufficient magnetic forces to bias the moments of magnetic particles in a flowing stream. A simplified physical principle was used to analyse the relative velocity of the magnetic particle in the confined space of a microchannel. The results revealed that the magnetic force contributed to the fluidic flow rate as well as to the hydrodynamic drag force. The relative velocity of magnetic particles was dependent on the frequency under an external magnetic field driven by an alternate current (ac) source. It showed that the magnetic gradient induced hysteresis characteristics of the transmission spectrum, associated with the interaction of superparamagnetic beads and magnetic field

Magnetic biosensor system to detect biological targets

KAUST Repository

Li, Fuquan; Gooneratne, Chinthaka Pasan; Kosel, Jü rgen

2012-01-01

magnetic concentration, magnetic as well as mechanical trapping and magnetic sensing. Target detection is based on the size difference between bare magnetic beads and magnetic beads with targets attached. This method remedies the need for a coating layer

Magnetic biosensor system to detect biological targets

KAUST Repository

Li, Fuquan

2012-09-01

Magneto-resistive sensors in combination with magnetic beads provide sensing platforms, which are small in size and highly sensitive. These platforms can be fully integrated with microchannels and electronics to enable devices capable of performing complex tasks. Commonly, a sandwich method is used that requires a specific coating of the sensor\\'s surface to immobilize magnetic beads and biological targets on top of the sensor. This paper concerns a micro device to detect biological targets using magnetic concentration, magnetic as well as mechanical trapping and magnetic sensing. Target detection is based on the size difference between bare magnetic beads and magnetic beads with targets attached. This method remedies the need for a coating layer and reduces the number of steps required to run an experiment. © 2012 IEEE.

On-chip measurements of Brownian relaxation vs. concentration of 40nm magnetic beads

DEFF Research Database (Denmark)

Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

2012-01-01

We present on-chip Brownian relaxation measurements on a logarithmic dilution series of 40 nm beads dispersed in water with bead concentrations between 16 mu g/ml and 4000 mu g/ml. The measurements are performed using a planar Hall effect bridge sensor at frequencies up to 1 MHz. No external fields...... are needed as the beads are magnetized by the field generated by the applied sensor bias current. We show that the Brownian relaxation frequency can be extracted from fitting the Cole-Cole model to measurements for bead concentrations of 64 mu g/ml or higher and that the measured dynamic magnetic response...... is proportional to the bead concentration. For bead concentrations higher than or equal to 500 mu g/ml, we extract a hydrodynamic diameter of 47(1) nm for the beads, which is close to the nominal bead size of 40 nm. Furthermore, we study the signal vs. bead concentration at a fixed frequency close to the Brownian...

Method and device for thermal control of biological and chemical reactions using magnetic particles or magnetic beads and variable magnetic fields

OpenAIRE

Zilch, C.; Gerdes, W.; Bauer, J.; Holschuh, K.

2009-01-01

The invention relates to a method for the thermal control of at least one temperature-dependent enzymatic reaction in the presence of magnetic particles, particularly nanoparticles, or magnetic beads, in vitro by heating the magnetic beads or magnetic particles to at least one defined target temperature using alternating magnetic fields. The thermally controllable enzymatic reaction carried out with the method according to the invention is preferably a PCR reaction or another reaction for elo...

Alginate/magnetite hybrid beads for magnetically stimulated release of dopamine.

Science.gov (United States)

Kondaveeti, Stalin; Cornejo, Daniel R; Petri, Denise Freitas Siqueira

2016-02-01

Hybrid beads composed of magnetite nanoparticles (MNP) and alginate (Alg) were synthesized and coded as Alg-MNP. They were incubated in dopamine (DOPA) solution (5 g/L), at pH 7.4 and 8 °C, during 12 h, promoting the DOPA loaded magnetic beads, coded as Alg-MNP/DOPA. The release of DOPA was further evaluated in the absence and the presence of external magnetic field (EMF) of 0.4 T. The products Alg-MNP and Alg-MNP/DOPA were characterized by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared vibrational spectroscopy (FTIR), UV spectrophotometry, thermogravimetric analyses (TGA), inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses and superconducting quantum interference device (SQUID) magnetometer. The magnetic and chemical properties of Alg-MNP beads were not affected by DOPA loading. The incorporation of DOPA into the beads depended on the pH and on the negative charge density. At pH 7.4 38% of DOPA were loaded into Alg-MNP beads, whereas at pH 2 or using neat Alg beads (lower charge density than Alg-MNP) the loading efficiency decreased to one third or less. In the absence of EMF, 24% of the loaded DOPA was released from Alg-MNP at pH 7.4 over a period of 26 h. The released amount increased to 33% under the stimulus of EMF. A model was proposed to explain the loading efficiency of charged drugs, as DOPA, into hybrid beads and the role played by EMF on delivery systems, where drug and matrix are oppositely charged. The results suggest that the alginate combined with magnetite nanoparticles is a promising system for release of DOPA in the presence of EMF. Copyright © 2015 Elsevier B.V. All rights reserved.

On-chip magnetic bead-based DNA melting curve analysis using a magnetoresistive sensor

DEFF Research Database (Denmark)

Rizzi, Giovanni; Østerberg, Frederik Westergaard; Henriksen, Anders Dahl

2014-01-01

We present real-time measurements of DNA melting curves in a chip-based system that detects the amount of surface-bound magnetic beads using magnetoresistive magnetic field sensors. The sensors detect the difference between the amount of beads bound to the top and bottom sensor branches....... The beads are magnetized by the field arising from the bias current passed through the sensors. We demonstrate the first on-chip measurements of the melting of DNA hybrids upon a ramping of the temperature. This overcomes the limitation of using a single washing condition at constant temperature. Moreover...

Cell surface clustering of Cadherin adhesion complex induced by antibody coated beads

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

Cadherin receptors mediate cell-cell adhesion, signal transduction and assembly of cytoskeletons. How a single transmembrane molecule Cadherin can be involved in multiple functions through modulating its binding activities with many membrane adhesion molecules and cytoskeletal components is an unanswered question which can be elucidated by clues from bead experiments. Human lung cells expressing N-Cadherin were examined. After co-incubation with anti-N-Cadherin monoclonal antibody coated beads, cell surface clustering of N-Cadherin was induced. Immunofluorescent detection demonstrated that in addition to Cadherin, β-Catenin, α-Catenin, α-Actinin and Actin fluorescence also aggregated respectively at the membrane site of bead attachment. Myosin heavy chain (MHC), another major component of Actin cytoskeleton, did not aggregate at the membrane site of bead attachment. Adhesion unrelated protein Con A and polylysine conjugated beads did not induce the clustering of adhesion molecules. It is indicated that the Cadherin/Catenins/α-Actinin/Actin complex is formed at Cadherin mediated cell adherens junction; occupancy and cell surface clustering of Cadherin is crucial for the formation of Cadherin adhesion protein complexes.

On-chip measurements of Brownian relaxation of magnetic beads with diameters from 10 nm to 250 nm

DEFF Research Database (Denmark)

Østerberg, Frederik Westergaard; Rizzi, Giovanni; Hansen, Mikkel Fougt

2013-01-01

We demonstrate the use of planar Hall effect magnetoresistive sensors for AC susceptibility measurements of magnetic beads with frequencies ranging from DC to 1 MHz. This wide frequency range allows for measuring Brownian relaxation of magnetic beads with diameters ranging from 10 nm to 250 nm....... Brownian relaxation is measured for six different magnetic bead types and their hydrodynamic diameters are determined. The hydrodynamic diameters are found to be within 40% of the nominal bead diameters. We discuss the applicability of the different bead types for volume-based biosensing with respect...... to sedimentation, magnetic trapping, and signal per bead. Among the investigated beads, we conclude that the beads with a nominal diameter of 80 nm are best suited for future on-chip volume-based biosensing experiments using planar Hall effect sensors....

Synthesis and characterization of monosize magnetic poly(glycidyl methacrylate) beads

Institute of Scientific and Technical Information of China (English)

Evrim Banu Alt1nta(s); Lokman Uzun; Adil Denizli

2007-01-01

Monosize, 1.6 μm, magnetic beads of poly(glycidyl methacrylate) [M-poly(GMA)], were prepared by dispersion polymerization in the presence of Fe3O4 nano-powder. Monosize M-poly(GMA) beads were characterized by swelling tests, density measurements, electron spin resonance (ESR), vibrating sample magnetometer (VSM) and scanning electron microscopy (SEM). The characteristic functional groups of M-poly(GMA)beads were analyzed by Fourier transform infrared spectrometer (FTIR). The M-poly(GMA) beads are highly uniform in size and have a spherical shape and non-porous structure. Polydispersity index (PDI) of M-poly(GMA) beads was calculated to be around 1.008. The hydrated density of the M-poly(GMA) beads measured at 25 ℃ was 1.14 g/cm3. The content of oxirane groups on the surface of the M-poly(GMA) sample was found to be 3.46 mmol/g by using perchloric acid titration. The specific surface area of the M-poly(GMA) beads was determined to be 3.2 m2/g.The equilibrium swelling ratio was 52%. The volume fraction of magnetite nanopowder in the M-poly(GMA) beads was found to be 4.5%. The g factor, that can be considered as a quantity characteristic of the molecules in which the unpaired electrons are located, was found to be 2.28for M-poly(GMA). The external magnetic field at resonance was calculated to be 2055 Gs which was found sufficient to excite all of the dipole moments present in 1.0 g of M-poly(GMA) sample.

Selective manipulation of superparamagnetic beads by a magnetic microchip

KAUST Repository

Gooneratne, Chinthaka Pasan; Yassine, Omar; Giouroudi, Ioanna; Kosel, Jü rgen

2013-01-01

In this paper, a magnetic microchip (MMC) is presented, to first trap and then selectively manipulate individual, superparamagnetic beads (SPBs) to another trapping site. Trapping sites are realized through soft magnetic micro disks made of Ni80Fe20

A magnetic bead-based method for concentrating DNA from human urine for downstream detection.

Directory of Open Access Journals (Sweden)

Hali Bordelon

Full Text Available Due to the presence of PCR inhibitors, PCR cannot be used directly on most clinical samples, including human urine, without pre-treatment. A magnetic bead-based strategy is one potential method to collect biomarkers from urine samples and separate the biomarkers from PCR inhibitors. In this report, a 1 mL urine sample was mixed within the bulb of a transfer pipette containing lyophilized nucleic acid-silica adsorption buffer and silica-coated magnetic beads. After mixing, the sample was transferred from the pipette bulb to a small diameter tube, and captured biomarkers were concentrated using magnetic entrainment of beads through pre-arrayed wash solutions separated by small air gaps. Feasibility was tested using synthetic segments of the 140 bp tuberculosis IS6110 DNA sequence spiked into pooled human urine samples. DNA recovery was evaluated by qPCR. Despite the presence of spiked DNA, no DNA was detectable in unextracted urine samples, presumably due to the presence of PCR inhibitors. However, following extraction with the magnetic bead-based method, we found that ∼50% of spiked TB DNA was recovered from human urine containing roughly 5×10(3 to 5×10(8 copies of IS6110 DNA. In addition, the DNA was concentrated approximately ten-fold into water. The final concentration of DNA in the eluate was 5×10(6, 14×10(6, and 8×10(6 copies/µL for 1, 3, and 5 mL urine samples, respectively. Lyophilized and freshly prepared reagents within the transfer pipette produced similar results, suggesting that long-term storage without refrigeration is possible. DNA recovery increased with the length of the spiked DNA segments from 10±0.9% for a 75 bp DNA sequence to 42±4% for a 100 bp segment and 58±9% for a 140 bp segment. The estimated LOD was 77 copies of DNA/µL of urine. The strategy presented here provides a simple means to achieve high nucleic acid recovery from easily obtained urine samples, which does not contain inhibitors of PCR.

Use of magnetic beads for Gram staining of bacteria in aqueous suspension.

Science.gov (United States)

Yazdankhah, S P; Sørum, H; Larsen, H J; Gogstad, G

2001-12-01

A Gram staining technique was developed using monodisperse magnetic beads in concentrating bacteria in suspension for downstream application. The technique does not require heat fixation of organisms, electrical power, or a microscope. Gram-negative and Gram-positive bacteria were identified macroscopically based on the colour of the suspension. The bacteria concentrated on magnetic beads may also be identified microscopically.

Magnetic chitosan/clay beads: A magsorbent for the removal of cationic dye from water

Energy Technology Data Exchange (ETDEWEB)

Bée, Agnès, E-mail: agnes.bee@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire PHENIX, F-75005 Paris (France); Obeid, Layaly, E-mail: lghannoum@hotmail.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire PHENIX, F-75005 Paris (France); CertiNergy Solutions, 33 avenue du Maine, BP 195, 75755 Paris Cedex 15 (France); Mbolantenaina, Rakotomalala, E-mail: mbolantenaina@yahoo.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire PHENIX, F-75005 Paris (France); Welschbillig, Mathias, E-mail: welschbillig@certinergysolutions.com [CertiNergy Solutions, 33 avenue du Maine, BP 195, 75755 Paris Cedex 15 (France); Talbot, Delphine, E-mail: delphine.talbot@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire PHENIX, F-75005 Paris (France)

2017-01-01

A magnetic composite material composed of magnetic nanoparticles and clay encapsulated in cross-linked chitosan beads was prepared, characterized and used as a magsorbent for the removal of a cationic dye, methylene blue (MB), from aqueous solutions. The magnetic properties of these beads represent an advantage to recover them at the end of the depollution process. The optimal weight ratio R=clay:chitosan for the removal of MB in a large range of pH was determined. For beads without clay, the maximal adsorption capacity of MB occurs in the pH range [9–12], while for beads with clay, the pH range extends by increasing the amount of clay to reach [3–12] for R>0.5. Adsorption isotherms show that the adsorption capacity of magnetic beads is equal to 82 mg/g. Moreover, the kinetics of dye adsorption is relatively fast since 50% of the dye is removed in the first 13 min for an initial MB concentration equal to 100 mg/L. The estimation of the number of adsorption sites at a given pH shows that the main driving force for adsorption of MB in a large range of pH is the electrostatic interaction between the positively charged dye and the permanent negative charges of clay. - Highlights: • A magsorbent based on magnetic nanoparticles and clay encapsulated in chitosan beads was prepared and characterized. • Clay played significant role for the removal of a cationic dye. • The magnetic beads exhibit a maximum adsorption capacity of 82 mg/g for methylene blue. • The pH range of the maximum adsorption extends from [9–12] to [3–12] by increasing the amount of clay. • The magsorbent could be magnetically removed from solution.

In vitro evaluation of chitosan coated- and uncoated-calcium alginate beads containing methyl salicylate-lactose physical mixture.

Science.gov (United States)

Tamilvanan, S; Karmegam, S

2012-01-01

Methyl salicylate-lactose physical mixture (1:1 and 1:1.5 ratios) was incorporated into calcium alginate beads by a coacervation method involving an ionotropic gelation/polyelectrolyte complexation approach. This study aims to determine the influence of chitosan coating over the beads on drug entrapment efficiency (DEE) and release characteristics in artificial saliva compared to that of the uncoated beads. Changes in formulation parameters (gelation time, concentrations of Ca(2+) and alginate) resulted in decrease in DEE of chitosan-uncoated beads (p methyl salicylate-lactose physical mixture.

"On-chip magnetic bead microarray using hydrodynamic focusing in a passive magnetic separator"

DEFF Research Database (Denmark)

Smistrup, Kristian; Kjeldsen, B.; Reimers, R.L.

2005-01-01

Implementing DNA and protein microarrays into lab-on-a-chip systems can be problematic since these are sensitive to heat and strong chemicals. Here, we describe the functionalization of a microchannel with two types of magnetic beads using hydrodynamic focusing combined with a passive magnetic...

Magnetic actuator for the control and mixing of magnetic bead-based reactions on-chip.

Science.gov (United States)

Berenguel-Alonso, Miguel; Granados, Xavier; Faraudo, Jordi; Alonso-Chamarro, Julián; Puyol, Mar

2014-10-01

While magnetic bead (MB)-based bioassays have been implemented in integrated devices, their handling on-chip is normally either not optimal--i.e. only trapping is achieved, with aggregation of the beads--or requires complex actuator systems. Herein, we describe a simple and low-cost magnetic actuator to trap and move MBs within a microfluidic chamber in order to enhance the mixing of a MB-based reaction. The magnetic actuator consists of a CD-shaped plastic unit with an arrangement of embedded magnets which, when rotating, generate the mixing. The magnetic actuator has been used to enhance the amplification reaction of an enzyme-linked fluorescence immunoassay to detect Escherichia coli O157:H7 whole cells, an enterohemorrhagic strain, which have caused several outbreaks in food and water samples. A 2.7-fold sensitivity enhancement was attained with a detection limit of 603 colony-forming units (CFU) /mL, when employing the magnetic actuator.

Applied Study on Magnetic Nanometer Beads in Preparation of Genechip Samples

Institute of Scientific and Technical Information of China (English)

陈慧; 高华方; 谢欣; 马雪梅; 杨渝珍

2004-01-01

Summary: A protocol for enrichment and adsorption of karyocyte from whole blood by using magnetic nanometer beads as solid-phase absorbents was presented. The PCR amplification could be accomplished by using the nanobeads with karyocyte as template directly and the PCR products were applied on an oligonucleotide array to do gene typing. The HLA-A PCR amplification system and a small HLA-A oligonucleotide microarray were applied as the platform and an experiment protocol of separating karyocyte from whole blood using the magnetic nanometer beads (Fe2O3) were set up.The experimental conditions were also discussed. It showed that pH level of PBS eluent, Taq enzyme quantity and fragment length of products could influent the amplification results, and the magnetic nano-beads could succeed in sample preparation in microarray to provide a promising way in automatic detection and lab-on-a-chip.

Improved Peak Capacity for Capillary Electrophoretic Separations of Enzyme Inhibitors with Activity-Based Detection Using Magnetic Bead Microreactors

Science.gov (United States)

Yan, Xiaoyan; Gilman, S. Douglass

2010-01-01

A technique for separating and detecting enzyme inhibitors was developed using capillary electrophoresis with an enzyme microreactor. The on-column enzyme microreactor was constructed using NdFeB magnet(s) to immobilize alkaline phosphatase-coated superparamagnetic beads (2.8 μm diameter) inside a capillary before the detection window. Enzyme inhibition assays were performed by injecting a plug of inhibitor into a capillary filled with the substrate, AttoPhos. Product generated in the enzyme microreactor was detected by laser-induced fluorescence. Inhibitor zones electrophoresed through the capillary, passed through the enzyme microreactor, and were observed as negative peaks due to decreased product formation. The goal of this study was to improve peak capacities for inhibitor separations relative to previous work, which combined continuous engagement electrophoretically mediated microanalysis (EMMA) and transient engagement EMMA to study enzyme inhibition. The effects of electric field strength, bead injection time and inhibitor concentrations on peak capacity and peak width were investigated. Peak capacities were increased to ≥20 under optimal conditions of electric field strength and bead injection time for inhibition assays with arsenate and theophylline. Five reversible inhibitors of alkaline phosphatase (theophylline, vanadate, arsenate, L-tryptophan and tungstate) were separated and detected to demonstrate the ability of this technique to analyze complex inhibitor mixtures. PMID:20024913

Removal of diethyl phthalate from aqueous phase using magnetic poly(EGDMA-VP) beads

Energy Technology Data Exchange (ETDEWEB)

Tuemay Oezer, Elif [Department of Chemistry, Uludag University, Bursa (Turkey); Osman, Bilgen, E-mail: bilgeno@uludag.edu.tr [Department of Chemistry, Uludag University, Bursa (Turkey); Kara, Ali; Besirli, Necati; Guecer, Seref [Department of Chemistry, Uludag University, Bursa (Turkey); Soezeri, Hueseyin [TUBITAK-UME, National Metrology Institute, PO Box 54 TR-41470, Gebze/Kocaeli (Turkey)

2012-08-30

Highlights: Black-Right-Pointing-Pointer Magnetic beads were prepared for removal of diethyl phthalate (DEP). Black-Right-Pointing-Pointer Total capacity of the beads was determined as 98.9 mg DEP per gram polymer. Black-Right-Pointing-Pointer Magnetic beads were regenerated easily and reused for DEP adsorption. Black-Right-Pointing-Pointer Adsorption isotherms, kinetics and thermodynamics were elucidated. - Abstract: The barium hexaferrite (BaFe{sub 12}O{sub 19}) containing magnetic poly(ethylene glycol dimethacrylate-vinyl pyridine), (mag-poly(EGDMA-VP)) beads (average diameter = 53-212 {mu}m) were synthesized and characterized. Their use as an adsorbent in the removal of diethyl phthalate (DEP) from an aqueous solution was investigated. The mag-poly(EGDMA-VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly(EGDMA-VP) beads were characterized by N{sub 2} adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM) and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DEP from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. The maximum DEP adsorption capacity of the mag-poly(EGDMA-VP) beads was determined as 98.9 mg/g at pH 3.0, 25 Degree-Sign C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DEP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.

Chip-Based Measurements of Brownian Relaxation of Magnetic Beads Using a Planar Hall Effect Magnetic Field Sensor

DEFF Research Database (Denmark)

Østerberg, Frederik Westergaard; Dalslet, Bjarke Thomas; Snakenborg, Detlef

2010-01-01

using only the self-field arising from the bias current applied to the sensors as excitation field. We present measurements on a suspension of magnetic beads with a nominal diameter of 250 nm vs. temperature and find that the observations are consistent with the Cole-Cole model for Brownian relaxation...... with a constant hydrodynamic bead diameter when the temperature dependence of the viscosity of water is taken into account. These measurements demonstrate the feasibility of performing measurements of the Brownian relaxation response in a lab-on-a-chip system and constitute the first step towards an integrated...... biosensor based on the detection of the dynamic response of magnetic beads....

Antibody-integrated and functionalized graphite-encapsulated magnetic beads, produced using ammonia gas plasma technology, for capturing Salmonella.

Science.gov (United States)

Sakudo, Akikazu; Chou, Han; Nagatsu, Masaaki

2015-03-01

Salmonella spp. is the single and most important causative agent of foodborne infections, especially involving foods such as eggs, milk and meat. To prevent infection, a reliable surveillance system is required that can quickly and sensitively detect Salmonella. Here, we describe the development of antibody-integrated magnetic beads that are functionalized by a novel strategy using ammonia gas plasma. Ammonia plasma, produced by a radio frequency (RF) power supply, was allowed to react with the surface of graphite-encapsulated magnetic beads, resulting in the introduction of amino groups. An anti-Salmonella antibody was then anchored by sulfide groups present on the protein surface to the amino groups of the magnetic beads via N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). The potential usefulness of these magnetic beads for capturing Salmonella was examined as follows. The beads were incubated with Salmonella in liquid medium and then separated from the supernatant by applying a magnetic field. After thorough washing, adsorption of Salmonella to the beads was confirmed by immunochromatography, polymerase chain reaction and a direct culture assay. Our findings indicate that the capture and concentration of Salmonella using the antibody-integrated magnetic beads was more efficient than commercial Dynabeads® anti-Salmonella, which are conventionally used for concentrating Salmonella from liquid cultures. We believe this novel bead technology will contribute to the enhanced detection of Salmonella. Copyright © 2015 Elsevier Ltd. All rights reserved.

An integrated open-cavity system for magnetic bead manipulation.

Science.gov (United States)

Abu-Nimeh, F T; Salem, F M

2013-02-01

Superparamagnetic beads are increasingly used in biomedical assays to manipulate, transport, and maneuver biomaterials. We present a low-cost integrated system designed in bulk CMOS to manipulate and separate biomedical magnetic beads. The system consists of 8 × 8 coil-arrays suitable for single bead manipulation, or collaborative multi-bead manipulation, using pseudo-parallel executions. We demonstrate the flexibility of the design in terms of different coil sizes, DC current levels, and layout techniques. In one array module example, the size of a single coil is 30 μm × 30 μm and the full array occupies an area of 248 μm × 248 μm in 0.5 μm CMOS technology. The programmable DC current source supports 8 discrete levels up to 1.5 mA. The total power consumption of the entire module is 9 mW when running at full power.

A half-ring GMR sensor for detection of magnetic beads immobilized on a circular micro-trap

KAUST Repository

Gooneratne, Chinthaka Pasan

2011-11-01

Utilizing magnetic principles in biological immunoassays is an attractive option given its ability to remotely and non-invasively manipulate and detect cells tagged with micro/nano size superparamagnetic type beads and due to the fact that even the most complex biological immunoassays will have very little magnetic effect. The presence of magnetic beads can be detected by a magnetic sensor which quantifies the amount of target cells present in the immunoassay. In order to increase the detection rate a circular conducting micro-trap is employed to attract, trap and transport the magnetic beads to the sensing area. In this research we propose a half-ring spin valve type giant magnetoresistance (GMR) sensor for the measurement of stray fields produced by 2 μm magnetic beads which are around the circular micro-trap. A couple of half-ring GMR sensors can be used to cover the entire circular border width, in order to detect the majority of the immobilized magnetic beads. Analytical and numerical analysis leading towards the fabrication of the half-ring GMR sensor are presented. DC characterization of the fabricated sensor showed a magnetoresistance of 5.9 %. Experimental results showed that the half-ring GMR sensor detected the presence of 2 μm magnetic beads. Hence, half-ring GMR sensors integrated with a circular micro-trap have great potential to be used as an effective disease diagnostic device. © 2011 IEEE.

A half-ring GMR sensor for detection of magnetic beads immobilized on a circular micro-trap

KAUST Repository

Gooneratne, Chinthaka Pasan; Liang, Cai; Useinov, Arthur; Kosel, Jü rgen; Giouroudi, Ioanna

2011-01-01

Utilizing magnetic principles in biological immunoassays is an attractive option given its ability to remotely and non-invasively manipulate and detect cells tagged with micro/nano size superparamagnetic type beads and due to the fact that even the most complex biological immunoassays will have very little magnetic effect. The presence of magnetic beads can be detected by a magnetic sensor which quantifies the amount of target cells present in the immunoassay. In order to increase the detection rate a circular conducting micro-trap is employed to attract, trap and transport the magnetic beads to the sensing area. In this research we propose a half-ring spin valve type giant magnetoresistance (GMR) sensor for the measurement of stray fields produced by 2 μm magnetic beads which are around the circular micro-trap. A couple of half-ring GMR sensors can be used to cover the entire circular border width, in order to detect the majority of the immobilized magnetic beads. Analytical and numerical analysis leading towards the fabrication of the half-ring GMR sensor are presented. DC characterization of the fabricated sensor showed a magnetoresistance of 5.9 %. Experimental results showed that the half-ring GMR sensor detected the presence of 2 μm magnetic beads. Hence, half-ring GMR sensors integrated with a circular micro-trap have great potential to be used as an effective disease diagnostic device. © 2011 IEEE.

Electrochemical immunoassay using magnetic beads for the determination of zearalenone in baby food: An anticipated analytical tool for food safety

International Nuclear Information System (INIS)

Hervas, Miriam; Lopez, Miguel Angel; Escarpa, Alberto

2009-01-01

In this work, electrochemical immunoassay involving magnetic beads to determine zearalenone in selected food samples has been developed. The immunoassay scheme has been based on a direct competitive immunoassay method in which antibody-coated magnetic beads were employed as the immobilisation support and horseradish peroxidase (HRP) was used as enzymatic label. Amperometric detection has been achieved through the addition of hydrogen peroxide substrate and hydroquinone as mediator. Analytical performance of the electrochemical immunoassay has been evaluated by analysis of maize certified reference material (CRM) and selected baby food samples. A detection limit (LOD) of 0.011 μg L -1 and EC 50 0.079 μg L -1 were obtained allowing the assessment of the detection of zearalenone mycotoxin. In addition, an excellent accuracy with a high recovery yield ranging between 95 and 108% has been obtained. The analytical features have shown the proposed electrochemical immunoassay to be a very powerful and timely screening tool for the food safety scene.

Electrochemical immunoassay using magnetic beads for the determination of zearalenone in baby food: an anticipated analytical tool for food safety.

Science.gov (United States)

Hervás, Miriam; López, Miguel Angel; Escarpa, Alberto

2009-10-27

In this work, electrochemical immunoassay involving magnetic beads to determine zearalenone in selected food samples has been developed. The immunoassay scheme has been based on a direct competitive immunoassay method in which antibody-coated magnetic beads were employed as the immobilisation support and horseradish peroxidase (HRP) was used as enzymatic label. Amperometric detection has been achieved through the addition of hydrogen peroxide substrate and hydroquinone as mediator. Analytical performance of the electrochemical immunoassay has been evaluated by analysis of maize certified reference material (CRM) and selected baby food samples. A detection limit (LOD) of 0.011 microg L(-1) and EC(50) 0.079 microg L(-1) were obtained allowing the assessment of the detection of zearalenone mycotoxin. In addition, an excellent accuracy with a high recovery yield ranging between 95 and 108% has been obtained. The analytical features have shown the proposed electrochemical immunoassay to be a very powerful and timely screening tool for the food safety scene.

Electrochemical immunoassay using magnetic beads for the determination of zearalenone in baby food: An anticipated analytical tool for food safety

Energy Technology Data Exchange (ETDEWEB)

Hervas, Miriam; Lopez, Miguel Angel [Departamento Quimica Analitica, Universidad de Alcala, Ctra. Madrid-Barcelona, Km. 33600, E-28871 Alcala de Henares, Madrid (Spain); Escarpa, Alberto, E-mail: alberto.escarpa@uah.es [Departamento Quimica Analitica, Universidad de Alcala, Ctra. Madrid-Barcelona, Km. 33600, E-28871 Alcala de Henares, Madrid (Spain)

2009-10-27

In this work, electrochemical immunoassay involving magnetic beads to determine zearalenone in selected food samples has been developed. The immunoassay scheme has been based on a direct competitive immunoassay method in which antibody-coated magnetic beads were employed as the immobilisation support and horseradish peroxidase (HRP) was used as enzymatic label. Amperometric detection has been achieved through the addition of hydrogen peroxide substrate and hydroquinone as mediator. Analytical performance of the electrochemical immunoassay has been evaluated by analysis of maize certified reference material (CRM) and selected baby food samples. A detection limit (LOD) of 0.011 {mu}g L{sup -1} and EC{sub 50} 0.079 {mu}g L{sup -1} were obtained allowing the assessment of the detection of zearalenone mycotoxin. In addition, an excellent accuracy with a high recovery yield ranging between 95 and 108% has been obtained. The analytical features have shown the proposed electrochemical immunoassay to be a very powerful and timely screening tool for the food safety scene.

Dual Recognition Strategy for Specific and Sensitive Detection of Bacteria Using Aptamer-Coated Magnetic Beads and Antibiotic-Capped Gold Nanoclusters.

Science.gov (United States)

Cheng, Dan; Yu, Mengqun; Fu, Fei; Han, Weiye; Li, Gan; Xie, Jianping; Song, Yang; Swihart, Mark T; Song, Erqun

2016-01-05

Food poisoning and infectious diseases caused by pathogenic bacteria such as Staphylococcus aureus (SA) are serious public health concerns. A method of specific, sensitive, and rapid detection of such bacteria is essential and important. This study presents a strategy that combines aptamer and antibiotic-based dual recognition units with magnetic enrichment and fluorescent detection to achieve specific and sensitive quantification of SA in authentic specimens and in the presence of much higher concentrations of other bacteria. Aptamer-coated magnetic beads (Apt-MB) were employed for specific capture of SA. Vancomycin-stabilized fluorescent gold nanoclusters (AuNCs@Van) were prepared by a simple one-step process and used for sensitive quantification of SA in the range of 32-10(8) cfu/mL with the detection limit of 16 cfu/mL via a fluorescence intensity measurement. And using this strategy, about 70 cfu/mL of SA in complex samples (containing 3 × 10(8) cfu/mL of other different contaminated bacteria) could be successfully detected. In comparison to prior studies, the developed strategy here not only simplifies the preparation procedure of the fluorescent probes (AuNCs@Van) to a great extent but also could sensitively quantify SA in the presence of much higher concentrations of other bacteria directly with good accuracy. Moreover, the aptamer and antibiotic used in this strategy are much less expensive and widely available compared to common-used antibodies, making it cost-effective. This general aptamer- and antibiotic-based dual recognition strategy, combined with magnetic enrichment and fluorescent detection of trace bacteria, shows great potential application in monitoring bacterial food contamination and infectious diseases.

Identification of RNAIII-binding proteins in Staphylococcus aureus using tethered RNAs and streptavidin aptamers based pull-down assay.

Science.gov (United States)

Zhang, Xu; Zhu, Qing; Tian, Tian; Zhao, Changlong; Zang, Jianye; Xue, Ting; Sun, Baolin

2015-05-15

It has been widely recognized that small RNAs (sRNAs) play important roles in physiology and virulence control in bacteria. In Staphylococcus aureus, many sRNAs have been identified and some of them have been functionally studied. Since it is difficult to identify RNA-binding proteins (RBPs), very little has been known about the RBPs in S. aureus, especially those associated with sRNAs. Here we adopted a tRNA scaffold streptavidin aptamer based pull-down assay to identify RBPs in S. aureus. The tethered RNA was successfully captured by the streptavidin magnetic beads, and proteins binding to RNAIII were isolated and analyzed by mass spectrometry. We have identified 81 proteins, and expressed heterologously 9 of them in Escherichia coli. The binding ability of the recombinant proteins with RNAIII was further analyzed by electrophoresis mobility shift assay, and the result indicates that proteins CshA, RNase J2, Era, Hu, WalR, Pyk, and FtsZ can bind to RNAIII. This study suggests that some proteins can bind to RNA III in S. aureus, and may be involved in RNA III function. And tRSA based pull-down assay is an effective method to search for RBPs in bacteria, which should facilitate the identification and functional study of RBPs in diverse bacterial species.

Decoupling Internalization, Acidification and Phagosmal-Endosomal/Iysosomal Phagocytosis of Internalin A coated Beads in epithelial cells

Energy Technology Data Exchange (ETDEWEB)

Blanchette, C D; Woo, Y; Thomas, C; Shen, N; Sulchek, T A; Hiddessen, A L

2008-12-22

Phagocytosis has been extensively examined in 'professional' phagocytic cells using pH sensitive dyes. However, in many of the previous studies, a separation between the end of internalization, beginning of acidification and completion of phagosomal-endosomal/lysosomal fusion was not clearly established, and in several cases, it was treated as a one-step process. In addition, very little work has been done to systematically examine phagosomal maturation in 'non-professional' phagocytic cells, such as epithelial cells. Therefore, in this study, we developed a simple and novel method to decouple and accurately measure particle internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion in Madin-Darby Canine Kidney (MDCK) and Caco-2 epithelial cells. Our method was developed using a pathogen mimetic system consisting of polystyrene beads coated with Internalin A (InlA), a membrane surface protein from Listeria monocytogenes known to trigger receptor-mediated internalization. We achieved independent measurements of the rates of internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion in epithelial cells by combining the InlA-coated beads (InlA-beads) with antibody quenching, pH sensitive dyes and endosomal/lysosomal dyes, as follows: the rate of InlA bead internalization was measured via antibody quenching of a pH independent dye (Alexa488) conjugated to InlA-beads, the rate at which phagosomes containing internalized InlA beads became acidified was measured using a pH dependent dye (FITC) conjugated to the beads and the rate of phagosomal-endosomal/lysosomal fusion was measured using a combination of unlabeled InlA-beads and an endosomal/lysosomal dye. By performing these independent measurements under identical experimental conditions, we were able to decouple the three processes and establish time scales for each. In a separate set of experiments, we also exploited the phagosomal acidification

Force measurements of a magnetic micro actuator proposed for a microvalve array

International Nuclear Information System (INIS)

Chang, Pauline J; Chang, Frank W; Yuen, Michelle C; Horsley, David A; Otillar, Robert

2014-01-01

Low-cost, easily-fabricated and power-efficient microvalves are necessary for many microfluidic lab-on-a-chip applications. In this study, we present a simple, low-power, scalable, CMOS-compatible magnetic actuator for microvalve applications composed of a paramagnetic bead as the ball valve over a picoliter reaction well etched into a silicon substrate. The paramagnetic bead, composed of either pure FeSi or magnetite in a SiO 2  matrix, is actuated by the local magnetic field gradient generated by a microcoil in an aqueous environment, and the reaction well is situated at the microcoil center. A permanent magnet beneath the microvalve device provides an external magnetic biasing field that magnetizes the bead, enabling bidirectional actuation and reducing the current required to actuate the bead to a level below 10 mA. The vertical and radial magnetic forces exerted on the bead by the microcoil were measured for both pure FeSi and composite beads and agree well with the predictions of 2D axisymmetric finite element method models. Vertical forces were within a range of 13–80 nN, and radial forces were 11–60 nN depending on the bead type. The threshold current required to initiate bead actuation was measured as a function of bead diameter and is found to scale inversely with volume for small beads, as expected based on the magnetic force model. To provide an estimate of the stiction force acting between the bead and the passivation layer on the substrate, repeated actuation trials were used to study the bead throw distance for substrates coated with silicon dioxide, Parylene-C, and photoresist. The stiction observed was lowest for a photoresist-coated substrate, while silicon dioxide and Parylene-C coated substrates exhibited similar levels of stiction. (paper)

Synthesis and Characterisation of Biocompatible Polymer-Conjugated Magnetic Beads for Enhancement Stability of Urease.

Science.gov (United States)

Doğaç, Yasemin Ispirli; Teke, Mustafa

2016-04-01

We reported natural polymer-conjugated magnetic featured urease systems for removal of urea effectively. The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70 °C), pH stability (4.0-9.0), operational stability (0-250 min), reusability (18 times) and storage stability (24 weeks) were studied for characterisation of the urease-encapsulated biocompatible polymer-conjugated magnetic beads. Also, the surface groups and chemical structure of the magnetic beads were determined by using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The all urease-encapsulated magnetic beads protected their stability of 30-45 % relative activity at 70 °C. A significant increase was observed at their pH stability compared with the free urease for both acidic and alkaline medium. Besides this, their repeatability activity were approximately 100 % during 4(th) run. They showed residual activity of 50 % after 16 weeks. The importance of this work is enhancement stability of immobilised urease by biocompatible polymer-conjugated magnetic beads for the industrial application based on removal of urea.

Asynchronous Magnetic Bead Rotation (AMBR Microviscometer for Label-Free DNA Analysis

Directory of Open Access Journals (Sweden)

Yunzi Li

2014-03-01

Full Text Available We have developed a label-free viscosity-based DNA detection system, using paramagnetic beads as an asynchronous magnetic bead rotation (AMBR microviscometer. We have demonstrated experimentally that the bead rotation period is linearly proportional to the viscosity of a DNA solution surrounding the paramagnetic bead, as expected theoretically. Simple optical measurement of asynchronous microbead motion determines solution viscosity precisely in microscale volumes, thus allowing an estimate of DNA concentration or average fragment length. The response of the AMBR microviscometer yields reproducible measurement of DNA solutions, enzymatic digestion reactions, and PCR systems at template concentrations across a 5000-fold range. The results demonstrate the feasibility of viscosity-based DNA detection using AMBR in microscale aqueous volumes.

Preparation of Immuno-magnetic Beads and Their Separation ＆ Detection to Ovary Cancer Cells

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

The organic monomer-molecule with nanometer magnetic powder by means of reforming the surface of nanometer magnetic powder have been synthesized.Magnetic beads in diameter of 2μm or so are obtained by controlling conditions.Ovary cancer cells of ascites are separated and ovary cancer cells of blood are detected by using immuno-magnetic beads linked with ovary cancer cell mono-antibodies.Results show that the specificity is 85%,sensitivity is 87%,accuracy is 84%,cells acquiring purity is 90%,cells activity is 92% and detection sensitivity is 25×10-7.

Caffeine: A novel green precursor for synthesis of magnetic CoFe2O4 nanoparticles and pH-sensitive magnetic alginate beads for drug delivery.

Science.gov (United States)

Amiri, Mahnaz; Salavati-Niasari, Masoud; Pardakhty, Abbas; Ahmadi, Meysam; Akbari, Ahmad

2017-07-01

Hydrogel beads are promising delivery systems for encapsulation and release of drugs due to the mild process of their fabrication from biopolymers. Magnetic CoFe 2 O 4 nanoparticles (MCFO, 9.72nm in diameter) were synthesized via a co-precipitation method using caffeine as a new environmentally friendly material in order to alkalinize the medium. Drug-targeting Magnetic beads based on CoFe 2 O 4 nanoparticles, sodium alginate and chlorpheniramine maleate (CPAM) were synthesized in the presence of Ca 2+ ions to obtain ionic cross-linked magnetic hydrogel beads. Nanoparticles as well as produced magnetic beads were thoroughly characterized by FTIR, XRD, SEM, nanosizer and VSM techniques. The swelling ratio of beads indicated pH-dependent property with maximum water absorbing at pH7.4. The in vitro release of beads exhibited significant behavior on the subject of nanoparticles concentration and alginate content. Biocompatibility of the CFO nanoparticles and MCFO/Alg beads are demonstrated through cytotoxicity test via MTT assay on U87 cell lines. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetic polymeric microspheres for protein adsorption

International Nuclear Information System (INIS)

Felinto, M.C.F.C.; Parra, D.F.; Lugao, A.B.; Batista, M.P.; Higa, O.Z.; Yamaura, M.; Camilo, R.L.; Ribela, M.T.C.P.; Sampaio, L.C.

2005-01-01

Magnetic beads consisting of polymer-coated manganese ferrite nanoparticles were prepared by the precipitation reaction of manganese ferrite into the channels of methyl methacrylate polymer beads by sodium hydroxide, resulting in MnMagBead. MnMagBead was characterized by infrared spectra (FTIR), thermogravimetric analysis of TGA/DTG and indicates the presence of -CO (carbonyl) groups and the MnFe 2 O 4 on the beads. Magnetization measurements were obtained at room temperature in magnetic fields up to 10 KOe using a vibrating sample magnetometer. Introductory Protein adsorption biological tests were processed using labeled I-125 albumin (BSA), and the activity was measured in a gamma counting spectrometer. These superparamagnetic beads exhibit the capacity to bind biological molecules such as proteins like albumin, with a good capability (5 x 10 -6 ) μg/100 mg of beads as compared with other magnetic resins studied in our group

A planar conducting micro-loop structure for transportation of magnetic beads: An approach towards rapid sensing and quantification of biological entities

KAUST Repository

Gooneratne, Chinthaka Pasan

2012-03-01

Magnetic beads are utilized effectively in a wide variety of medical applications due to their small size, biocompatibility and large surface to volume ratio. Microfluidic lab-on-a-chip (LOC) devices, which utilize magnetic beads, are promising tools for accurate and rapid cell sorting and counting. Effective manipulation of beads is a critical factor for the performance of LOC devices. In this paper we propose a planar conducting micro-loop structure to trap, manipulate and transport magnetic beads. Current through the micro-loops produces magnetic field gradients that are proportional to the force required to manipulate the beads. Numerical analyses were performed to study the magnetic forces and their spatial distributions. Experimental results showed that magnetic beads could not only be transported towards a target region, e.g., for sensing purposes, but also the trapping rate could be increased by switching current between the different loops in the micro-loop structure. This method could lead to rapid and accurate quantification of biological entities tagged with magnetic beads. Copyright © 2012 American Scientific Publishers. All rights reserved.

Signal amplification for impedimetric genosensing using gold-streptavidin nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Bonanni, A.; Esplandiu, M.J. [Sensors and Biosensors Group, Department of Chemistry, Universitat Autonoma de Barcelona, Edifici Cn, 08193 Bellaterra, Barcelona (Spain); Valle, M. del [Sensors and Biosensors Group, Department of Chemistry, Universitat Autonoma de Barcelona, Edifici Cn, 08193 Bellaterra, Barcelona (Spain)], E-mail: manel.delvalle@uab.es

2008-04-20

Streptavidin-coated gold nanoparticles (strept-AuNPs) were used in this work to amplify the impedimetric signal generated in a biosensor detecting the DNA hybridization event. Probe oligomer was adsorbed onto a graphite epoxy composite (GEC) electrode surface and the impedance measurement was performed in a solution containing the redox marker ferrocyanide/ferricyanide. The biotinylated complementary oligomer was used as target. The change of interfacial charge transfer resistance (R{sub ct}), experimented by the redox marker, was recorded to confirm the hybrid formation. The addition of strept-AuNPs, binding to the target due to the strong streptavidin-biotin interaction, led to a further increment of R{sub ct} thus obtaining significant signal amplification. Strept-AuNPs on the electrode surface were observed by scanning electron microscopy (SEM) after silver enhancement treatment. A competitive binding assay was also performed using unlabelled DNA target to demonstrate its applicability to real sample analysis.

Selective manipulation of superparamagnetic beads by a magnetic microchip

KAUST Repository

Gooneratne, Chinthaka Pasan

2013-07-01

In this paper, a magnetic microchip (MMC) is presented, to first trap and then selectively manipulate individual, superparamagnetic beads (SPBs) to another trapping site. Trapping sites are realized through soft magnetic micro disks made of Ni80Fe20, and SPB motion is controlled by current-carrying, tapered, conducting lines made of Au. The MMC was realized using standard microfabrication techniques and provides a cheap and versatile platform for microfluidic systems for cell manipulation. © 2013 IEEE.

Breakthrough analysis for water disinfection using silver nanoparticles coated resin beads in fixed-bed column

International Nuclear Information System (INIS)

Mthombeni, Nomcebo H.; Mpenyana-Monyatsi, Lizzy; Onyango, Maurice S.; Momba, Maggie N.B.

2012-01-01

Highlights: ► Performance of silver nanoparticles coated resin in water disinfection is presented. ► Sigmoidal models are used to describe breakthrough curves. ► The performance of the media in water disinfection is affected by process variables. ► Test with environmental water shows the media is effective in water disinfection. - Abstract: This study demonstrates the use of silver nanoparticles coated resin beads in deactivating microbes in drinking water in a column filtration system. The coated resin beads are characterized using X-ray diffraction (XRD), Fourier transform infra-red (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS) to confirm the functional groups, morphology and the presence of silver nanoparticles on the surface of the resin. The performance of the coated resin is evaluated as a function of bed mass, initial bacterial concentration and flow rate using Escherichia coli as model microbial contaminant in water. The survival curves of E. coli are expressed as breakthrough curves (BTCs), which are modeled using sigmoidal regression equations to obtain relevant rate parameters. The number of bed volumes processed at breakthrough point and capacity of the bed are used as performance indicators. Results show that performance increases with a decrease in initial bacterial concentration, an increase in flow rate and an increase in bed mass.

Planar Hall effect bridge sensors with NiFe/Cu/IrMn stack optimized for self-field magnetic bead detection

DEFF Research Database (Denmark)

Henriksen, Anders Dahl; Rizzi, Giovanni; Hansen, Mikkel Fougt

2016-01-01

, and 30 nm, and 0 ≤ tCu ≤ 0.6 nm. The sensors were characterized by magnetic hysteresis measurements, by measurements of the sensor response vs. applied field, and by measurements of the sensor response to a suspension of magnetic beads magnetized by the sensor self-field due to the sensor bias current....... The exchange bias field was found to decay exponentially with tCu and inversely with tFM. The reduced exchange field for larger values of tFM and tCu resulted in higher sensitivities to both magnetic fields and magnetic beads. We argue that the maximum magnetic bead signal is limited by Joule heating...

Capture of DNA in microfluidic channel using magnetic beads: increasing capture efficiency with integrated microfluidic mixer

DEFF Research Database (Denmark)

Lund-Olesen, Torsten; Dufva, Hans Martin; Hansen, Mikkel Fougt

2007-01-01

We have studied the hybridization of target DNA in solution with probe DNA on magnetic beads immobilized on the channel sidewalls in a magnetic bead separator. The hybridization is carried out under a liquid flow and is diffusion limited. Two systems are compared: one with a straight microfluidic...... place on the surface in a microfluidic system....

Detection of a magnetic bead by hybrid nanodevices using scanning gate microscopy

Science.gov (United States)

Corte-León, H.; Krzysteczko, P.; Marchi, F.; Motte, J.-F.; Manzin, A.; Schumacher, H. W.; Antonov, V.; Kazakova, O.

2016-05-01

Hybrid ferromagnetic(Py)/non-magnetic metal(Au) junctions with a width of 400 nm are studied by magnetotransport measurements, magnetic scanning gate microscopy (SGM) with a magnetic bead (MB) attached to the probe, and micromagnetic simulations. In the transverse geometry, the devices demonstrate a characteristic magnetoresistive behavior that depends on the direction of the in plane magnetic field, with minimum/maximum variation when the field is applied parallel/perpendicular to the Py wire. The SGM is performed with a NdFeB bead of 1.6 μm diameter attached to the scanning probe. Our results demonstrate that the hybrid junction can be used to detect this type of MB. A rough approximation of the sensing volume of the junction has the shape of elliptical cylinder with the volume of ˜1.51 μm3. Micromagnetic simulations coupled to a magnetotransport model including anisotropic magnetoresistance and planar Hall effects are in good agreement with the experimental findings, enabling the interpretation of the SGM images.

Radioimmunotargeting with modified streptavidin-biotin. Final report

International Nuclear Information System (INIS)

Cantor, C.R.

1998-01-01

For the past three years, the author has designed and produced several useful streptavidin variants, characterized their properties both in vitro and in vivo, and developed methods and strategies needed for characterization of each molecule and the entire radioimmunotargeting approaches using these molecules. In molecular design of these streptavidin mutants, an enhanced molecular modeling method, including empirical free energy calculations was used which is of great assistance in designing streptavidin mutants effectively and intelligently. When the original proposal was submitted in 1992, the reviewers were rather skeptical about the proposal to design successfully a various streptavidin mutants, particularly a dimeric streptavidin and multi-flavor streptavidins. These were clearly very challenging tasks, but now the author has the molecules in hand. This demonstrates the power of the molecular modeling method he is using and suggests the feasibility of further enhancements of these and other streptavidin variants by the molecular modeling capability. The author has also developed signal amplification methods which could introduce large amounts of radioisotopes specifically at target tumor sites in the radioimmunotargeting approaches

Diffraction-based BioCD biosensor for point-of-care diagnostics

Science.gov (United States)

Choi, H.; Chang, C.; Savran, C.; Nolte, D.

2018-02-01

The BioCD platform technology uses spinning-disk interferometry to detect molecular binding to target molecular probes in biological samples. Interferometric configurations have included differential phase contrast and in-line quadrature detection. For the detection of extremely low analyte concentrations, nano- or microparticles can enhance the signal through background-free diffraction detection. Diffraction signal measurements on BioCD biosensors are achieved by forming gratings on a disc surface. The grating pattern was printed with biotinylated bovine serum albumin (BSA) and streptavidin coated beads were deployed. The diameter of the beads was 1 micron and strong protein bonding occurs between BSA and streptavidin-coated beads at the printed location. The wavelength for the protein binding detection was 635 nm. The periodic pattern on the disc amplified scattered light into the first-order diffraction position. The diffracted signal contains Mie scattering and a randomly-distributed-bead noise contributions. Variation of the grating pattern periodicity modulates the diffraction efficiency. To test multiple spatial frequencies within a single scan, we designed a fan-shaped grating to perform frequency filter multiplexing on a diffraction-based BioCD.

A micro-pillar array to trap magnetic beads in microfluidic systems

KAUST Repository

Gooneratne, Chinthaka Pasan

2012-12-01

A micro-pillar array (MPA) is proposed in this paper to trap and separate magnetic beads (MBs) in microfluidic systems. MBs are used in many biomedical applications due to being compatible in dimension to biomolecules, the large surface area available to attach biomolecules, and the fact that they can be controlled by a magnetic field. Trapping and separating these labeled biomolecules is an important step toward achieving reliable and accurate quantification for disease diagnostics. Nickel Iron (Ni50Fe 50) micro-pillars were fabricated on a Silicon (Si) substrate by standard microfabrication techniques. Experimental results showed that MBs could be trapped on the MPA at the single bead level and separated from other non-target particles. This principle can easily be extended to trap and separate target biomolecules in heterogeneous biological samples. © 2012 IEEE.

Bioinspired methodology for preparing magnetic responsive chitosan beads to be integrated in a tubular bioreactor for biomedical applications.

Science.gov (United States)

Song, Wenlong; Oliveira, Mariana B; Sher, Praveen; Gil, Sara; Nóbrega, J Miguel; Mano, João F

2013-08-01

Magnetic responsive chitosan beads were prepared using a methodology inspired by the rolling of water droplets over lotus leaves. Liquid precursors containing chitosan and magnetic microparticles were dispensed in the form of spherical droplets and crosslinked with genipin over synthetic superhydrophobic surfaces. Scanning electronic microscopy, histology and micro-computed tomography were employed to characterize the structure of the prepared composite beads and the inner distribution of the magnetic particles. Cellular metabolic activity tests showed that fibroblasts-like (L929 cell line) can adhere and proliferate on the prepared chitosan beads. We hypothesize that such spherical biomaterials could be integrated in a new concept of tubular bioreactor. The magnetic beads can be immobilized by an external magnetic field at specific positions and may be transported along the bioreactor by the drag of the culture medium flow. The system behavior was also studied through numerical modeling, which allowed to identify the relative importance of the main parameters, and to conclude that the distance between carrier beads plays a major role on their interaction with the culture medium and, consequently, on the overall system performance. In an up-scaled version of this bioreactor, the herein presented system may comprise different chambers in serial or parallel configurations. This constitutes a simple way of preparing magnetic responsive beads combined with a new design of bioreactor, which may find application in biomedicine and biotechnology, including in cell expansion for tissue engineering or for the production of therapeutic proteins to be used in cell therapies.

Bioinspired methodology for preparing magnetic responsive chitosan beads to be integrated in a tubular bioreactor for biomedical applications

International Nuclear Information System (INIS)

Song, Wenlong; Oliveira, Mariana B; Sher, Praveen; Gil, Sara; Mano, João F; Nóbrega, J Miguel

2013-01-01

Magnetic responsive chitosan beads were prepared using a methodology inspired by the rolling of water droplets over lotus leaves. Liquid precursors containing chitosan and magnetic microparticles were dispensed in the form of spherical droplets and crosslinked with genipin over synthetic superhydrophobic surfaces. Scanning electronic microscopy, histology and micro-computed tomography were employed to characterize the structure of the prepared composite beads and the inner distribution of the magnetic particles. Cellular metabolic activity tests showed that fibroblasts-like (L929 cell line) can adhere and proliferate on the prepared chitosan beads. We hypothesize that such spherical biomaterials could be integrated in a new concept of tubular bioreactor. The magnetic beads can be immobilized by an external magnetic field at specific positions and may be transported along the bioreactor by the drag of the culture medium flow. The system behavior was also studied through numerical modeling, which allowed to identify the relative importance of the main parameters, and to conclude that the distance between carrier beads plays a major role on their interaction with the culture medium and, consequently, on the overall system performance. In an up-scaled version of this bioreactor, the herein presented system may comprise different chambers in serial or parallel configurations. This constitutes a simple way of preparing magnetic responsive beads combined with a new design of bioreactor, which may find application in biomedicine and biotechnology, including in cell expansion for tissue engineering or for the production of therapeutic proteins to be used in cell therapies. (paper)

Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

Energy Technology Data Exchange (ETDEWEB)

Kistrup, Kasper, E-mail: kkis@nanotech.dtu.dk [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby (Denmark); Skotte Sørensen, Karen, E-mail: karen@nanotech.dtu.dk [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby (Denmark); Center for Integrated Point of Care Technologies (CiPoC), DELTA, Venlighedsvej 4, DK-2870 Hørsholm (Denmark); Wolff, Anders, E-mail: anders.wolff@nanotech.dtu.dk [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby (Denmark); Fougt Hansen, Mikkel, E-mail: mikkel.hansen@nanotech.dtu.dk [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345 East, DK-2800 Kongens Lyngby (Denmark)

2015-04-15

We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/µg and 1.72(14) nL/µg were found for Milli-Q water and lysis-binding buffer, respectively. - Highlights: • We present an all-polymer mass producible passive filled microfluidic chip system. • Rapid system fabrication is obtained by injection moulding and ultrasonic welding. • The system is made for single-use nucleic acid extraction using magnetic beads. • We systematically map compatibility of the chip system with various surfactants. • We quantify the volume carry-over of magnetic beads in water and 0.1% triton-X solution.

Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

International Nuclear Information System (INIS)

Kistrup, Kasper; Skotte Sørensen, Karen; Wolff, Anders; Fougt Hansen, Mikkel

2015-01-01

We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/µg and 1.72(14) nL/µg were found for Milli-Q water and lysis-binding buffer, respectively. - Highlights: • We present an all-polymer mass producible passive filled microfluidic chip system. • Rapid system fabrication is obtained by injection moulding and ultrasonic welding. • The system is made for single-use nucleic acid extraction using magnetic beads. • We systematically map compatibility of the chip system with various surfactants. • We quantify the volume carry-over of magnetic beads in water and 0.1% triton-X solution

Structure-Guided Design of an Engineered Streptavidin with Reusability to Purify Streptavidin-Binding Peptide Tagged Proteins or Biotinylated Proteins

OpenAIRE

Wu, Sau-Ching; Wong, Sui-Lam

2013-01-01

Development of a high-affinity streptavidin-binding peptide (SBP) tag allows the tagged recombinant proteins to be affinity purified using the streptavidin matrix without the need of biotinylation. The major limitation of this powerful technology is the requirement to use biotin to elute the SBP-tagged proteins from the streptavidin matrix. Tight biotin binding by streptavidin essentially allows the matrix to be used only once. To address this problem, differences in interactions of biotin an...

Streptavidin-coated gold nanoparticles: critical role of oligonucleotides on stability and fractal aggregation

Directory of Open Access Journals (Sweden)

Roberta D'Agata

2017-01-01

Full Text Available Gold nanoparticles (AuNPs exhibit unique properties that can be modulated through a tailored surface functionalization, enabling their targeted use in biochemical sensing and medical diagnostics. In particular, streptavidin-modified AuNPs are increasingly used for biosensing purposes. We report here a study of AuNPs surface-functionalized with streptavidin-biotinylated oligonucleotide, focussing on the role played by the oligonucleotide probes in the stabilization/destabilization of the functionalized nanoparticle dispersion. The behaviour of the modified AuNP dispersion as a consequence of the competitive displacement of the biotinylated oligonucleotide has been investigated and the critical role of displaced oligonucletides in triggering the quasi one-dimensional aggregation of nanoparticles is demonstrated for the first time. The thorough understanding of the fundamental properties of bioconjugated AuNPs is of great importance for the design of highly sensitive and reliable functionalized AuNP-based assays.

Combining magnetic nanoparticle with biotinylated nanobodies for rapid and sensitive detection of influenza H3N2

Science.gov (United States)

Zhu, Min; Hu, Yonghong; Li, Guirong; Ou, Weijun; Mao, Panyong; Xin, Shaojie; Wan, Yakun

2014-09-01

Our objective is to develop a rapid and sensitive assay based on magnetic beads to detect the concentration of influenza H3N2. The possibility of using variable domain heavy-chain antibodies (nanobody) as diagnostic tools for influenza H3N2 was investigated. A healthy camel was immunized with inactivated influenza H3N2. A nanobody library of 8 × 108 clones was constructed and phage displayed. After three successive biopanning steps, H3N2-specific nanobodies were successfully isolated, expressed in Escherichia coli, and purified. Sequence analysis of the nanobodies revealed that we possessed four classes of nanobodies against H3N2. Two nanobodies were further used to prepare our rapid diagnostic kit. Biotinylated nanobody was effectively immobilized onto the surface of streptavidin magnetic beads. The modified magnetic beads with nanobody capture specifically influenza H3N2 and can still be recognized by nanobodies conjugated to horseradish peroxidase (HRP) conjugates. Under optimized conditions, the present immunoassay exhibited a relatively high sensitive detection with a limit of 50 ng/mL. In conclusion, by combining magnetic beads with specific nanobodies, this assay provides a promising influenza detection assay to develop a potential rapid, sensitive, and low-cost diagnostic tool to screen for influenza infections.

One pot synthesis of new poly(vinyl alcohol) blended natural polymer based magnetic hydrogel beads: Controlled natural anticancer alkaloid delivery system.

Science.gov (United States)

Kesavan, Mookkandi Palsamy; Ayyanaar, Srinivasan; Lenin, Nayagam; Sankarganesh, Murugesan; Dhaveethu Raja, Jeyaraj; Rajesh, Jegathalaprathaban

2018-02-01

Facile one-pot synthesis has been demonstrated for new biocompatible and dual responsive magnetic iron oxide nanoparticles cross-linked poly(vinyl alcohol) (PVA) blended natural polymer chitosan (CS) based hydrogel beads (mCS-PVA) as a controlled natural anticancer alkaloid Luotonin A (LuA) delivery system. The prepared magnetic hydrogel beads were characterized using powder X-ray diffraction measurement, Fourier transform-infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and vibrating sample magnetometer. The magnetic hydrogel beads are exhibited significant water retention and follow the second order kinetic model in swelling study. The swelling ratio of the magnetic gel beads increased by the addition of PVA and showed a maximum swelling ratio of 40.83 ± 1.01 g/g and follows non-Fickian water transport mechanism. Stimuli responsive mCS and mCS-PVA hydrogel beads functionalized with LuA is demonstrated for controlled release at physiological pH and under magnetic field. The magnetic hydrogel beads show highest LuA releasing efficacy at acidic medium (pH = 5.0) with maximum efficiency of 73.33 ± 1.44%. This efficacy may also be tuned by altering the external magnetic field as well as the weight percentage (wt %) of polyethylene glycol. It is clearly that the newly produced magnetic hydrogel beads can be served as an effective intestinal LuA delivery system. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 543-551, 2018. © 2017 Wiley Periodicals, Inc.

Flow Cytometry-Based Bead-Binding Assay for Measuring Receptor Ligand Specificity

NARCIS (Netherlands)

Sprokholt, Joris K.; Hertoghs, Nina; Geijtenbeek, Teunis B. H.

2016-01-01

In this chapter we describe a fluorescent bead-binding assay, which is an efficient and feasible method to measure interaction between ligands and receptors on cells. In principle, any ligand can be coated on fluorescent beads either directly or via antibodies. Binding between ligand-coated beads

Concanavalin A immobilized magnetic poly(glycidyl methacrylate) beads for prostate specific antigen binding.

Science.gov (United States)

Idil, Neslihan; Perçin, Işık; Karakoç, Veyis; Yavuz, Handan; Aksöz, Nilüfer; Denizli, Adil

2015-10-01

The aim of this study was to prepare Concanavalin A (Con A) immobilized magnetic poly(glycidyl methacrylate) (mPGMA) beads for prostate specific antigen (PSA) binding and to study binding capacities of the beads using lectin-glycoprotein interactions. Firstly, iron oxide nanoparticles were synthesized by co-precipitation method and then, beads were synthesized by dispersion polymerization in the presence of iron oxide nanoparticles. Con A molecules were both covalently immobilized onto the beads directly and through the spacer arm (1,6-diaminohexane-HDMA). The total PSA and free PSA binding onto the mPGMA-HDMA-Con A beads were higher than that of the mPGMA-Con A beads. Maximum PSA binding capacity was observed as 91.2 ng/g. Approximately 45% of the bound PSA was eluted by using 0.1 M mannose as elution agent. The mPGMA-HDMA-Con A beads could be reused without a remarkable decrease in the binding capacities after 5 binding-desorption cycles. Serum fractions were analyzed using SDS-PAGE. The mPGMA-HDMA-Con A beads could be useful for the detection of PSA and suggested as a model system for other glycoprotein biomarkers. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic iron oxide nanoparticles (MIONs) cross-linked natural polymer-based hybrid gel beads: Controlled nano anti-TB drug delivery application.

Science.gov (United States)

Kesavan, Mookkandi Palsamy; Ayyanaar, Srinivasan; Vijayakumar, Vijayaparthasarathi; Dhaveethu Raja, Jeyaraj; Annaraj, Jamespandi; Sakthipandi, Kathiresan; Rajesh, Jegathalaprathaban

2018-04-01

The nanosized rifampicin (RIF) has been prepared to increase the solubility in aqueous solution, which leads to remarkable enhancement of its bioavailability and their convenient delivery system studied by newly produced nontoxic, biodegradable magnetic iron oxide nanoparticles (MIONs) cross-linked polyethylene glycol hybrid chitosan (mCS-PEG) gel beads. The functionalization of both nano RIF and mCS-PEG gel beads were studied using various spectroscopic and microscopic techniques. The size of prepared nano RIF was found to be 70.20 ± 3.50 nm. The mechanical stability and swelling ratio of the magnetic gel beads increased by the addition of PEG with a maximum swelling ratio of 38.67 ± 0.29 g/g. Interestingly, this magnetic gel bead has dual responsive assets in the nano drug delivery application (pH and the magnetic field). As we expected, magnetic gel beads show higher nano drug releasing efficacy at acidic medium (pH = 5.0) with maximum efficiency of 71.00 ± 0.87%. This efficacy may also be tuned by altering the external magnetic field and the weight percentage (wt%) of PEG. These results suggest that such a dual responsive magnetic gel beads can be used as a potential system in the nano drug delivery applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1039-1050, 2018. © 2017 Wiley Periodicals, Inc.

A micro-pillar array to trap magnetic beads in microfluidic systems

KAUST Repository

Gooneratne, Chinthaka Pasan; Kosel, Jü rgen

2012-01-01

A micro-pillar array (MPA) is proposed in this paper to trap and separate magnetic beads (MBs) in microfluidic systems. MBs are used in many biomedical applications due to being compatible in dimension to biomolecules, the large surface area

Bead magnetorelaxometry with an on-chip magnetoresistive sensor

DEFF Research Database (Denmark)

Dalslet, Bjarke Thomas; Damsgaard, Christian Danvad; Donolato, Marco

2011-01-01

Magnetorelaxometry measurements on suspensions of magnetic beads are demonstrated using a planar Hall effect sensor chip embedded in a microfluidic system. The alternating magnetic field used for magnetizing the beads is provided by the sensor bias current and the complex magnetic susceptibility...... spectra are recorded as the 2nd harmonic of the sensor response. The complex magnetic susceptibility signal appears when a magnetic bead suspension is injected, it scales with the bead concentration, and it follows the Cole-Cole expression for Brownian relaxation. The complex magnetic susceptibility...... signal resembles that from conventional magnetorelaxometry done on the same samples apart from an offset in Brownian relaxation frequency. The time dependence of the signal can be rationalized as originating from sedimented beads....

Detection of a magnetic bead by hybrid nanodevices using scanning gate microscopy

Directory of Open Access Journals (Sweden)

H. Corte-León

2016-05-01

Full Text Available Hybrid ferromagnetic(Py/non-magnetic metal(Au junctions with a width of 400 nm are studied by magnetotransport measurements, magnetic scanning gate microscopy (SGM with a magnetic bead (MB attached to the probe, and micromagnetic simulations. In the transverse geometry, the devices demonstrate a characteristic magnetoresistive behavior that depends on the direction of the in plane magnetic field, with minimum/maximum variation when the field is applied parallel/perpendicular to the Py wire. The SGM is performed with a NdFeB bead of 1.6 μm diameter attached to the scanning probe. Our results demonstrate that the hybrid junction can be used to detect this type of MB. A rough approximation of the sensing volume of the junction has the shape of elliptical cylinder with the volume of ∼1.51 μm3. Micromagnetic simulations coupled to a magnetotransport model including anisotropic magnetoresistance and planar Hall effects are in good agreement with the experimental findings, enabling the interpretation of the SGM images.

Construction of microscale structures in enclosed microfluidic networks by using a magnetic beads based method.

Science.gov (United States)

Wang, Zhenyu; Zhang, Xiaojuan; Yang, Jun; Yang, Zhong; Wan, Xiaoping; Hu, Ning; Zheng, Xiaolin

2013-08-20

A large number of microscale structures have been used to elaborate flowing control or complex biological and chemical reaction on microfluidic chips. However, it is still inconvenient to fabricate microstructures with different heights (or depths) on the same substrate. These kinds of microstructures can be fabricated by using the photolithography and wet-etching method step by step, but involves time-consuming design and fabrication process, as well as complicated alignment of different masters. In addition, few existing methods can be used to perform fabrication within enclosed microfluidic networks. It is also difficult to change or remove existing microstructures within these networks. In this study, a magnetic-beads-based approach is presented to build microstructures in enclosed microfluidic networks. Electromagnetic field generated by microfabricated conducting wires (coils) is used to manipulate and trap magnetic beads on the bottom surface of a microchannel. These trapped beads are accumulated to form a microscale pile with desired shape, which can adjust liquid flow, dock cells, modify surface, and do some other things as those fabricated microstructures. Once the electromagnetic field is changed, trapped beads may form new shapes or be removed by a liquid flow. Besides being used in microfabrication, this magnetic-beads-based method can be used for novel microfluidic manipulation. It has been validated by forming microscale dam structure for cell docking and modified surface for cell patterning, as well as guiding the growth of neurons. Copyright © 2013 Elsevier B.V. All rights reserved.

A multi-purpose ultrasonic streaming mixer for integrated magnetic bead ELISAs

International Nuclear Information System (INIS)

Brandhoff, Lukas; Lang, Walter; Vellekoop, Michael J; Zirath, Helene; Peham, Johannes; Wiesinger-Mayr, Herbert; Salas, Mariugenia; Haller, Anna; Spittler, Andreas; Schnetz, Guntram

2015-01-01

We present an ultrasonic streaming mixer for disposable and on-chip magnetic bead ELISAs. The ultrasonic transducer is placed at system-level to keep cost per chip as low as possible, and is coupled to the chip by means of a solid ultrasonic horn. The system provides mixing of liquids, as well as dispersion of the superparamagnetic beads in the ELISA. Additionally it can be used clean the chamber surface from nonspecifically bound proteins during the washing steps in the ELISA protocol. Using our system the time for the ELISA protocol has been greatly reduced down to 30 min. (paper)

Using Magnets and Magnetic Beads to Dissect Signaling Pathways Activated by Mechanical Tension Applied to Cells

Science.gov (United States)

Marjoram, R.J.; Guilluy, C; Burridge, K.

2015-01-01

Cellular tension has implications in normal biology and pathology. Membrane adhesion receptors serve as conduits for mechanotransduction that lead to cellular responses. Ligand-conjugated magnetic beads are a useful tool in the study of how cells sense and respond to tension. Here we detail methods for their use in applying tension to cells and strategies for analyzing the results. We demonstrate the methods by analyzing mechanotransduction through VE-cadherin on endothelial cells using both permanent magnets and magnetic tweezers. PMID:26427549

Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

Science.gov (United States)

Kistrup, Kasper; Skotte Sørensen, Karen; Wolff, Anders; Fougt Hansen, Mikkel

2015-04-01

We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/μg and 1.72(14) nL/μg were found for Milli-Q water and lysis-binding buffer, respectively.

Kinase-loaded magnetic beads for sequential in vitro phosphorylation of peptides and proteins.

Science.gov (United States)

Hromadkova, Lenka; Kupcik, Rudolf; Vajrychova, Marie; Prikryl, Petr; Charvatova, Andrea; Jankovicova, Barbora; Ripova, Daniela; Bilkova, Zuzana; Slovakova, Marcela

2018-01-15

Post-translational modifications, including phosphorylation, greatly impact the physiological function of proteins, especially those that are natively unfolded and implicated in many neurodegenerative diseases. However, structural and functional studies of such proteins require fully defined phosphorylation, including those that are not physiological. Thus, the kinases ERK2 and GSK-3β were immobilized to various superparamagnetic beads with carboxylic, aldehyde, Ni 2+ , or Co 3+ functional groups, with a view to efficiently phosphorylate peptides and proteins in vitro. Full phosphorylation of specific synthetic peptides confirmed that beads were successfully loaded with kinases. Remarkably, enzymes covalently immobilized on carboxylated SeraMag beads remained active upon reuse, with residual activity after 10 uses 99.5 ± 0.34% for GSK-3β and 36.2 ± 2.01% for ERK2. The beads were also used to sequentially phosphorylate recombinant tau, which in vivo is a biomarker of Alzheimer's disease. Thus, a system consisting of two fully active kinases immobilized to magnetic beads is demonstrated for the first time. In comparison to soluble enzymes, the beads are easier to handle, reusable, and thus low-cost. Importantly, these beads are also convenient to remove from reactions to minimize contamination of phosphorylated products or to exchange with other kinases.

The Drug Release Profile from Calcium-induced Alginate Gel Beads Coated with an Alginate Hydrolysate

Directory of Open Access Journals (Sweden)

Susumu Kawashima

2007-11-01

Full Text Available Calcium-induced alginate gel bead (Alg-Ca coated with an alginate hydrolysate(Alg, e.g. the guluronic acid block (GB was prepared and the model drug, hydrocortisonerelease profiles were investigated under simulated gastrointestinal conditions. Theirmolecular weights were one sixth or one tenth that of Alg and the diffraction patterns of thehydrolysates resembled that of Alg. The drug release rate from Alg-Ca coated with GBapparently lowered than that of Alg-Ca (coating-free in the gastric juice (pH1.2. And thecoating did not resist the disintegration of Alg-Ca in the intestinal juice (pH 6.8 and thegel erosion accelerated the drug release. On the other hand, for the coated Alg-Cacontaining chitosan, the drug release showed zero-order kinetics without rapid erosion ofAlg-Ca. The drug release rate from Alg-Ca was able to be controlled by the coating andmodifying the composition of the gel matrix.

Characterization of PEI-coated superparamagnetic iron oxide nanoparticles for transfection: Size distribution, colloidal properties and DNA interaction

Energy Technology Data Exchange (ETDEWEB)

Steitz, Benedikt [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Hofmann, Heinrich [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Kamau, Sarah W. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zuerich, Zurich (Switzerland); Hassa, Paul O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zuerich, Zurich (Switzerland); Hottiger, Michael O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zuerich, Zurich (Switzerland); Rechenberg, Brigitte von [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Hofmann-Amtenbrink, Magarethe [MatSearch, Chemin Jean Pavillard 14, 1009 Pully (Switzerland); Petri-Fink, Alke [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland)]. E-mail: alke.fink@epfl.ch

2007-04-15

Superparamagnetic iron oxide nanoparticles (SPIONs) were coated with polyethylenimine. Here, we briefly describe the synthesis as well as DNA:PEI:SPION complexes and the characterization of the compounds according to their particle size, {zeta}-potential, morphology, DNA complexing ability, magnetic sedimentation, and colloidal stability. PEI coating of SPIONs led to colloidally stable beads even in high salt concentrations over a wide pH range. DNA plasmids and PCR products encoding for green fluorescent protein were associated with the described beads. The complexes were added to cells and exposed to permanent and pulsating magnetic fields. Presence of these magnetic fields significantly increased the transfection efficiency.

Characterization of PEI-coated superparamagnetic iron oxide nanoparticles for transfection: Size distribution, colloidal properties and DNA interaction

International Nuclear Information System (INIS)

Steitz, Benedikt; Hofmann, Heinrich; Kamau, Sarah W.; Hassa, Paul O.; Hottiger, Michael O.; Rechenberg, Brigitte von; Hofmann-Amtenbrink, Magarethe; Petri-Fink, Alke

2007-01-01

Superparamagnetic iron oxide nanoparticles (SPIONs) were coated with polyethylenimine. Here, we briefly describe the synthesis as well as DNA:PEI:SPION complexes and the characterization of the compounds according to their particle size, ζ-potential, morphology, DNA complexing ability, magnetic sedimentation, and colloidal stability. PEI coating of SPIONs led to colloidally stable beads even in high salt concentrations over a wide pH range. DNA plasmids and PCR products encoding for green fluorescent protein were associated with the described beads. The complexes were added to cells and exposed to permanent and pulsating magnetic fields. Presence of these magnetic fields significantly increased the transfection efficiency

Synthesis of magnetic hollow silica using polystyrene bead as a template

International Nuclear Information System (INIS)

Wu, W.; Caruntu, D.; Martin, A.; Yu, M.H.; O'Connor, C.J.; Zhou, W.L.; Chen, J.-F.

2007-01-01

In this paper, we report a new route to synthesize novel magnetic hollow silica nanospheres (MHSNs) using polystyrene particles as sacrificial templates, and TEOS and Fe 3 O 4 as precursors. TEM, EDS, XRD, and SQUID were applied to characterize MHSNs. TEM and EDS results show that the MHSNs consist of about 200 nm of hollow cores and ∼35 nm shells with ∼10 nm of Fe 3 O 4 nanoparticles embedded. The polystyrene beads were successfully removed by immersing the as-prepared silica nanocomposite in a toluene solution. XRD results demonstrate that the Fe 3 O 4 magnetic nanoparticles still keep spinel structure even heated at low temperature. The surface status of the polystyrene beads and Fe 3 O 4 nanoparticles has an important effect on the formation of the MHSNs. The MHSNs present a superparamagnetism at room temperature by SQUID measurement. The MHSNs have potential applications in biosystem and nanomedicine

High heat generation ability in AC magnetic field for nano-sized magnetic Y3Fe5O12 powder prepared by bead milling

International Nuclear Information System (INIS)

Aono, Hiromichi; Ebara, Hiroki; Senba, Ryota; Naohara, Takashi; Maehara, Tsunehiro; Hirazawa, Hideyuki; Watanabe, Yuji

2012-01-01

Nano-sized magnetic Y 3 Fe 5 O 12 ferrite having a high heat generation ability in an AC magnetic field was prepared by bead milling. A commercial powder sample (non-milled sample) of ca. 2.9 μm in particle size did not show any temperature enhancement in the AC magnetic field. The heat generation ability in the AC magnetic field improved with a decrease in the average crystallite size for the bead-milled Y 3 Fe 5 O 12 ferrites. The highest heat ability in the AC magnetic field was for the fine Y 3 Fe 5 O 12 powder with a 15-nm crystallite size (the samples were milled for 4 h using 0.1 mmφ beads). The heat generation ability of the excessively milled Y 3 Fe 5 O 12 samples decreased. The main reason for the high heat generation property of the milled samples was ascribed to an increase in the Néel relaxation of the superparamagnetic material. The heat generation ability was not influenced by the concentration of the ferrite powder. For the samples milled for 4 h using 0.1 mmφ beads, the heat generation ability (W g −1 ) was estimated using a 3.58×10 −4 fH 2 frequency (f/kHz) and the magnetic field (H/kA m −1 ), which is the highest reported value of superparamagnetic materials. - Highlights: ► The nano-sized Y 3 Fe 5 O 12 powder prepared by bead-milling has the highest heat generation ability in an AC magnetic field. ► The heat generation properties are ascribed to an increase in the Néel relaxation of the superparamagnetic material. ► The heat ability (W g −1 ) can be estimated using 3.58×10 −4 fH 2 (f=kHz, H=kA m −1 ). ► This is an expectable material for use in a drug delivery system for the thermal coagulation therapy of cancer tumors.

Investigation on rare earth magnets recycling by organophosphoric extractant encapsulated polymeric beads for separation of dysprosium

International Nuclear Information System (INIS)

Yadav, Kartikey K.; Singh, D.K.; Kain, V.

2017-01-01

Rare earth elements (REEs) are a basic requirement of the electronics and new industries including green technology. In the present work an organophosphoric extractant encapsulating polyethersulfone (PES) beads has been developed and employed for dysprosium (Dy) separation from aqueous stream. Polyethersulfonic beads encapsulating PC88A were prepared by phase inversion method. During the synthesis of the beads, preparatory parameters were also optimized to obtain best suited beads which were subsequently characterized for their encapsulation capacity and micro structural investigation. The results obtained in the present investigation suggested that PES/PVAJPC88A composite beads could be used for separation of rare earths from aqueous medium obtained from the solubilisation of magnetic scrap materials

Expression of streptavidin gene in bacteria and plants

International Nuclear Information System (INIS)

Guan, Xueni; Wurtele, E.S.; Nikolau, B.J.

1990-01-01

Six biotin-containing proteins are present in plants, representing at least four different biotin enzymes. The physiological function of these biotin enzymes is not understood. Streptavidin, a protein from Streptomyces avidinii, binds tightly and specifically to biotin causing inactivation of biotin enzymes. One approach to elucidating the physiological function of biotin enzymes in plant metabolism is to create transgenic plants expressing the streptavidin gene. A plasmid containing a fused streptavidin-beta-galactosidase gene has been expressed in E. coli. We also have constructed various fusion genes that include an altered CaMV 35S promoter, signal peptides to target the streptavidin protein to specific organelles, and the streptavidin coding gene. We are examining the expression of these genes in cells of carrot

Observation of the dynamics of magnetically induced chains of sub-micron superparamagnetic beads in aqueous solutions by laser light scattering

International Nuclear Information System (INIS)

Tanizawa, Y; Tashiro, T; Sandhu, A; Ko, P J

2013-01-01

Optical monitoring the behaviour of magnetically induced self-assembled chains of superparamagnetic beads (SPBs) are of interest for biomedical applications such as biosensors. However, it is difficult to directly monitor magnetically induced self-assembly of sub-micron nano-beads with conventional optical microscopes. Here, we describe the optical observation of the dynamics of magnetically induced self-assembled rotating chains of 130 nm SPBs in aqueous solutions by laser light scattering. Magnetic fields of ∼1 kOe were applied to control the self-assembly chains of SPBs and their behaviour analyzed by monitoring the intensity of laser light scattered from the chain structures. We compared the light scattering from chains that were formed only by the application of external fields with chains formed by beads functionalized by EDC, where chemical reactions lead to the bonding of individual beads to form chains. The EDC experiments are a precursor to experiments on molecular recognition applications for biomedical diagnostics.

Magnetic bead manipulation in a sub-microliter fluid volume applicable for biosensing

NARCIS (Netherlands)

Derks, R.J.S.; Wimberger-Friedl, R.; Prins, M.W.J.; Dietzel, A.H.

2007-01-01

Magnetic actuation principles using superparamagnetic beads suspended in a fluid are studied in this paper. An exptl. setup contg. a submicroliter fluid vol. surrounded by four miniaturized electromagnets was designed and fabricated. On the basis of optical velocity measurements, the induced

Magnetic polymer beads: Recent trends and developments in synthetic design and applications

KAUST Repository

Philippova, Olga

2011-04-01

The paper describes the synthesis, properties and applications of magnetic polymer beads. State-of-the-art, future challenges, and promising trends in this field are analyzed. New applications in oil recovery are described. © 2010 Elsevier Ltd. All rights reserved.

Magnetic polymer beads: Recent trends and developments in synthetic design and applications

KAUST Repository

Philippova, Olga; Barabanova, Anna; Molchanov, Vyacheslav; Khokhlov, Alexei

2011-01-01

The paper describes the synthesis, properties and applications of magnetic polymer beads. State-of-the-art, future challenges, and promising trends in this field are analyzed. New applications in oil recovery are described. © 2010 Elsevier Ltd. All rights reserved.

Comparison of anti-CD3 and anti-CD28-coated beads with soluble anti-CD3 for expanding human T cells: Differing impact on CD8 T cell phenotype and responsiveness to restimulation

Directory of Open Access Journals (Sweden)

Kurlander Roger J

2010-10-01

Full Text Available Abstract Background The ability to expand virus- or tumor-specific T cells without damaging their functional capabilities is critical for success adoptive transfer immunotherapy of patients with opportunistic infection or tumor. Careful comparisons can help identify expansion methods better suited for particular clinical settings and identify recurrent deficiencies requiring new innovation. Methods We compared the efficacy of magnetic beads coated with anti-CD3 and anti-CD28 (anti-CD3/CD28 beads, and soluble anti-CD3 plus mixed mononuclear cells (designated a rapid expansion protocol or REP in expanding normal human T cells. Results Both anti-CD3/CD28 beads and soluble anti-CD3 promoted extensive expansion. Beads stimulated greater CD4 cell growth (geometric mean of 56- versus 27-fold (p Conclusions Anti-CD3/CD28 beads are highly effective for expanding CD4 cells, but soluble anti-CD3 has significant potential advantages for expanding CD8 T cells, particularly where preservation of phenotypically "young" CD8 cells would be desirable, or where the T cells of interest have been antigen-stimulated in vitro or in vivo in the recent past.

A label-free colorimetric aptasensor for simple, sensitive and selective detection of Pt (II) based on platinum (II)-oligonucleotide coordination induced gold nanoparticles aggregation.

Science.gov (United States)

Fan, Daoqing; Zhai, Qingfeng; Zhou, Weijun; Zhu, Xiaoqing; Wang, Erkang; Dong, Shaojun

2016-11-15

Herein, a gold nanoparticles (AuNPs) based label-free colorimetric aptasensor for simple, sensitive and selective detection of Pt (II) was constructed for the first time. Four bases (G-G mismatch) mismatched streptavidin aptamer (MSAA) was used to protect AuNPs from salt-induced aggregation and recognize Pt (II) specifically. Only in the presence of Pt (II), coordination occurs between G-G bases and Pt (II), leading to the activation of streptavidin aptamer. Streptavidin coated magnetic beads (MBs) were used as separation agent to separate Pt (II)-coordinated MSAA. The residual less amount of MSAA could not efficiently protect AuNPs anymore and aggregation of AuNPs will produce a colorimetric product. With the addition of Pt (II), a pale purple-to-blue color variation could be observed by the naked eye. A detection limit of 150nM and a linear range from 0.6μM to 12.5μM for Pt (II) could be achieved without any amplification. Copyright © 2016 Elsevier B.V. All rights reserved.

Aptasensor development for detection of virus in water

DEFF Research Database (Denmark)

Kirkegaard, Julie

of three types of waterborne viruses: norovirus, rotavirus and hepatitis A virus. The development of the aptasensor involved sample preparation for aptamer selection of rotavirus and hepatitis A virus, an iterative design process of the aptasensor, investigation of the surface immobilisation of aptamers...... and finally an impedimetric electrical characterisation of the sensor. The sample preparation of the rotavirus was based on purification and biotinylation of the virus to meet the requirements of the aptamer selection process. The selection process, performed by an external collaborator, was based...... on streptavidin coated magnetic bead separation, hence the needed biotinylation. It was found that the BPH linker gave the highest yield when the biotinylated rotavirus were immobilised onto the beads. The design of the viral aptasensor was determined by an iterative design process. The final chip design...

Iron Nanoparticles (Fe3O4 Used to Synthesize Magnetic Sodium Alginate Hydrogel Beads for the Removal of Basic Blue 159 from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Atiyeh Ghajarieh

2017-11-01

Full Text Available Dyes are a main source of pollutants in textile plant effluents. Due to their molecular structure, they are usually toxic, carcinogenous, and persistent in the environment. The aim of the present work was to explore the removal of basic blue159 (BB159 using magnetic sodium alginate hydrogel beads. Magnetic sodium alginate hydrogel beads were initially synthesized  accoriodng to Rocher method using CaCl2 as a crosslink agent. Fourier transform infrared spectroscopy (FTIR was then employed to examine the functional groups on the surface of the magnetic sodium alginate hydrogel beads. In a third stage, the magnetic properties of the beads were measured using a vibrating sample magnetometer (VSM and the magnetic parameters were calculated. Subsequently, the effects of such parameters as adsorbent dosage, pH, initial concentration of dye, and contact time were evaluated on the BB159 removal efficiency of the adsorbent used. Finally, the Langmuir, Freundlich, Temkin, and B.E.T models were exploited to study the adsorption isotherm of BB159 onto the magnetic sodium alginate hydrogel beads. It was found that the magnetic sodium alginate beads possess both –COO and –OH groups that play important roles in the adsorption of the positively charged BB159 dye. A saturation magnetization equal to 21/8(emu/g was obtained for the sodium alginate beads/nano Fe3O4. Results also revealed that the highest dye removal from aqueous solutions was achieved at pH=11 in 120 minutes for 9 grams of the adsorbent. The study indicated that BB159 removal using the magnetic sodium alginate hydrogel beads as the adsorbent obeys the Langmuir model. Moreover, it was shown that the efficiency of the process for BB159 removal from aqueous solutions was satisfactory (85%.

Comparison of La3+ and mixed rare earths-loaded magnetic chitosan beads for fluoride adsorption

DEFF Research Database (Denmark)

Liang, Peng; An, Ruiqi; Li, Ruifen

2018-01-01

La3+ and mixed-rare earth magnetic chitosan beads (MCLB and MCLRB) were successfully prepared for fluoride removal, respectively. The adsorbents were characterized by scanning electron microscope and magnetic response. Batch experiments were carried out to investigate the adsorbent performance...

A magnetic bead-based ligand binding assay to facilitate human kynurenine 3-monooxygenase drug discovery.

Science.gov (United States)

Wilson, Kris; Mole, Damian J; Homer, Natalie Z M; Iredale, John P; Auer, Manfred; Webster, Scott P

2015-02-01

Human kynurenine 3-monooxygenase (KMO) is emerging as an important drug target enzyme in a number of inflammatory and neurodegenerative disease states. Recombinant protein production of KMO, and therefore discovery of KMO ligands, is challenging due to a large membrane targeting domain at the C-terminus of the enzyme that causes stability, solubility, and purification difficulties. The purpose of our investigation was to develop a suitable screening method for targeting human KMO and other similarly challenging drug targets. Here, we report the development of a magnetic bead-based binding assay using mass spectrometry detection for human KMO protein. The assay incorporates isolation of FLAG-tagged KMO enzyme on protein A magnetic beads. The protein-bound beads are incubated with potential binding compounds before specific cleavage of the protein-compound complexes from the beads. Mass spectrometry analysis is used to identify the compounds that demonstrate specific binding affinity for the target protein. The technique was validated using known inhibitors of KMO. This assay is a robust alternative to traditional ligand-binding assays for challenging protein targets, and it overcomes specific difficulties associated with isolating human KMO. © 2014 Society for Laboratory Automation and Screening.

Hydrodynamic Torques and Rotations of Superparamagnetic Bead Dimers

Science.gov (United States)

Pease, Christopher; Etheridge, J.; Wijesinghe, H. S.; Pierce, C. J.; Prikockis, M. V.; Sooryakumar, R.

Chains of micro-magnetic particles are often rotated with external magnetic fields for many lab-on-a-chip technologies such as transporting beads or mixing fluids. These applications benefit from faster responses of the actuated particles. In a rotating magnetic field, the magnetization of superparamagnetic beads, created from embedded magnetic nano-particles within a polymer matrix, is largely characterized by induced dipoles mip along the direction of the field. In addition there is often a weak dipole mop that orients out-of-phase with the external rotating field. On a two-bead dimer, the simplest chain of beads, mop contributes a torque Γm in addition to the torque from mip. For dimers with beads unbound to each other, mop rotates individual beads which generate an additional hydrodynamic torque on the dimer. Whereas, mop directly torques bound dimers. Our results show that Γm significantly alters the average frequency-dependent dimer rotation rate for both bound and unbound monomers and, when mop exceeds a critical value, increases the maximum dimer rotation frequency. Models that include magnetic and hydrodynamics torques provide good agreement with the experimental findings over a range of field frequencies.

[Evaluation of TB-beads assay utilizing the technique of magnetic beads--an innovative assay method for detection of acid fast bacilli].

Science.gov (United States)

Ohkuma, Masanori; Ikeda, Katsuyoshi; Obayashi, Konen; Ando, Yukio; Koriyama, Toyoyasu; Kimu, Minhi; Hirose, Nobuyuki; Nagasawa, Zenzo; Miyamoto, Hiroshi

2012-01-01

The centrifuge method with the use of Semi-Alkalin Proteinase (SAP) and NALC-NaOH, recommended by the "2007 edition of the assay guideline for detection of Mycobacterium tuberculosis," has significantly contributed to improving the sensitivities and specificities of both smear and culture tests for detection of acid fast bacilli (AFB). However, this method poses some challenges in terms of its cumbersome and time-consuming assay protocol. "TB-beads (Kyokuto Pharmaceutical Industrial Co., Ltd.)" is a newly-developed method for detection of AFB utilizing magnetic beads. We evaluated the quality of this method in comparison with the centrifuge method, focusing on the results of smear and culture tests. This evaluation study was conducted using both 5 positive and 5 negative sputum samples. The sensitivity of TB-beads for fluorescent smear tests, conducted using "Acri-stain," was almost the same as that of the centrifuge method. One advantage of TB-beads, however, was that it was very convenient to practice microscopic observation due to the clear background of the smeared glass slides. The comparison of the contamination rates between the two methods showed that TB-beads suggested significantly lower contamination rates. The centrifuge method resulted in 50% and 60% of contamination rates for HK Semisolid Isolation Medium and BacT/ALERT MP, respectively. On the other hand, the contamination rates of TB-beads for both of the culture methods were only 10%. With regard to the 5 positive sputum samples, the comparison of the detection rates between the centrifuge and TB-Beads method was made utilizing Myco Acid, Ogawa K, and BacT/ALERT MP. The TB-Beads method suggested higher detection rates for Myco Acid and Ogawa K, while there were no significant differences between the two methods for BacT/ALERT MP (16-23 days). TB-beads is an easy method that allows to simplify the process of smear tests, and contributes to significantly reducing the contamination rate of culture

Structure-guided design of an engineered streptavidin with reusability to purify streptavidin-binding peptide tagged proteins or biotinylated proteins.

Directory of Open Access Journals (Sweden)

Sau-Ching Wu

Full Text Available Development of a high-affinity streptavidin-binding peptide (SBP tag allows the tagged recombinant proteins to be affinity purified using the streptavidin matrix without the need of biotinylation. The major limitation of this powerful technology is the requirement to use biotin to elute the SBP-tagged proteins from the streptavidin matrix. Tight biotin binding by streptavidin essentially allows the matrix to be used only once. To address this problem, differences in interactions of biotin and SBP with streptavidin were explored. Loop3-4 which serves as a mobile lid for the biotin binding pocket in streptavidin is in the closed state with biotin binding. In contrast, this loop is in the open state with SBP binding. Replacement of glycine-48 with a bulkier residue (threonine in this loop selectively reduces the biotin binding affinity (Kd from 4 × 10(-14 M to 4.45 × 10(-10 M without affecting the SBP binding affinity. Introduction of a second mutation (S27A to the first mutein (G48T results in the development of a novel engineered streptavidin SAVSBPM18 which could be recombinantly produced in the functional form from Bacillus subtilis via secretion. To form an intact binding pocket for tight binding of SBP, two diagonally oriented subunits in a tetrameric streptavidin are required. It is vital for SAVSBPM18 to be stably in the tetrameric state in solution. This was confirmed using an HPLC/Laser light scattering system. SAVSBPM18 retains high binding affinity to SBP but has reversible biotin binding capability. The SAVSBPM18 matrix can be applied to affinity purify SBP-tagged proteins or biotinylated molecules to homogeneity with high recovery in a reusable manner. A mild washing step is sufficient to regenerate the matrix which can be reused for multiple rounds. Other applications including development of automated protein purification systems, lab-on-a-chip micro-devices, reusable biosensors, bioreactors and microarrays, and strippable

Structure-guided design of an engineered streptavidin with reusability to purify streptavidin-binding peptide tagged proteins or biotinylated proteins.

Science.gov (United States)

Wu, Sau-Ching; Wong, Sui-Lam

2013-01-01

Development of a high-affinity streptavidin-binding peptide (SBP) tag allows the tagged recombinant proteins to be affinity purified using the streptavidin matrix without the need of biotinylation. The major limitation of this powerful technology is the requirement to use biotin to elute the SBP-tagged proteins from the streptavidin matrix. Tight biotin binding by streptavidin essentially allows the matrix to be used only once. To address this problem, differences in interactions of biotin and SBP with streptavidin were explored. Loop3-4 which serves as a mobile lid for the biotin binding pocket in streptavidin is in the closed state with biotin binding. In contrast, this loop is in the open state with SBP binding. Replacement of glycine-48 with a bulkier residue (threonine) in this loop selectively reduces the biotin binding affinity (Kd) from 4 × 10(-14) M to 4.45 × 10(-10) M without affecting the SBP binding affinity. Introduction of a second mutation (S27A) to the first mutein (G48T) results in the development of a novel engineered streptavidin SAVSBPM18 which could be recombinantly produced in the functional form from Bacillus subtilis via secretion. To form an intact binding pocket for tight binding of SBP, two diagonally oriented subunits in a tetrameric streptavidin are required. It is vital for SAVSBPM18 to be stably in the tetrameric state in solution. This was confirmed using an HPLC/Laser light scattering system. SAVSBPM18 retains high binding affinity to SBP but has reversible biotin binding capability. The SAVSBPM18 matrix can be applied to affinity purify SBP-tagged proteins or biotinylated molecules to homogeneity with high recovery in a reusable manner. A mild washing step is sufficient to regenerate the matrix which can be reused for multiple rounds. Other applications including development of automated protein purification systems, lab-on-a-chip micro-devices, reusable biosensors, bioreactors and microarrays, and strippable detection agents for

Detection of fine magnetic particles coated on a thread using an HTS-SQUID

International Nuclear Information System (INIS)

Kawagishi, K.; Itozaki, H.; Kondo, T.; Komori, K.; Koetitz, R.

2004-01-01

Polymer-coated magnetic particles, which contain superparamagnetic ferrite nanoparticles, were attached to a nylon thread of 0.35 mm in diameter and were detected by an HTS-SQUID. The length of the sample attached into the thread was within 3 mm and its interval was 30 mm. The particles were magnetized by a coil applied dc field or by a magnet of 1.4 T. The thread ran 2 mm under the SQUID with 20-100 mm/s of the rate. Signals of magnetic beads were detected and the peak-to-peak amplitude of the signals was directly proportional to the applied field and the weight of the magnetic particles. Obtained peak-to-peak amplitude for 20 ng of magnetite particles was 350 pT at 0.25 mT of applied dc field with noise of 18 pT, and estimated detection limit was 10 ng. S/N ratio was improved by the remanence measurement using the magnet and 5.8 ng of detection limit was obtained. This measurement has been proved to be promising for the continuous analysis of ultra dilute DNA solution

Preparation of ionic-crosslinked chitosan-based gel beads and effect of reaction conditions on drug release behaviors.

Science.gov (United States)

Chen, Shilan; Liu, Mingzhu; Jin, Shuping; Wang, Bin

2008-02-12

Drug-loaded chitosan (CS) beads were prepared under simple and mild condition using trisodium citrate as ionic crosslinker. The beads were further coated with poly(methacrylic acid) (PMAA) by dipping the beads in PMAA aqueous solution. The surface and cross-section morphology of these beads were observed by scanning electron microscopy and the observation showed that the coating beads had core-shell structure. In vitro release of model drug from these beads obtained under different reaction conditions was investigated in buffer medium (pH 1.8). The results showed that the rapid drug release was restrained by PMAA coating and the optimum conditions for preparing CS-based drug-loaded beads were decided through the effect of reaction conditions on the drug release behaviors. In addition, the drug release mechanism of CS-based drug-loaded beads was analyzed by Peppa's potential equation. According to this study, the ionic-crosslinked CS beads coated by PMAA could serve as suitable candidate for drug site-specific carrier in stomach.

Superparamagnetic poly(methyl methacrylate) beads for nattokinase purification from fermentation broth.

Science.gov (United States)

Yang, Chengli; Xing, Jianmin; Guan, Yueping; Liu, Huizhou

2006-09-01

An effective method for purification of nattokinase from fermentation broth using magnetic poly(methyl methacrylate) (PMMA) beads immobilized with p-aminobenzamidine was proposed in this study. Firstly, magnetic PMMA beads with a narrow size distribution were prepared by spraying suspension polymerization. Then, they were highly functionalized via transesterification reaction with polyethylene glycol. The surface hydroxyl-modified magnetic beads obtained were further modified with chloroethylamine to transfer the surface amino-modified magnetic functional beads. The morphology and surface functionality of the magnetic beads were examined by scanning electron microscopy and Fourier transform infrared. An affinity ligand, p-aminobenzamidine was covalently immobilized to the amino-modified magnetic beads by the glutaraldehyde method for nattokinase purification directly from the fermentation broth. The purification factor and the recovery of the enzyme activity were found to be 8.7 and 85%, respectively. The purification of nattokinase from fermentation broth by magnetic beads only took 40 min, which shows a very fast purification of nattokinase compared to traditional purification methods.

Evaluation of different strategies for magnetic particle functionalization with DNA aptamers.

Science.gov (United States)

Pérez-Ruiz, Elena; Lammertyn, Jeroen; Spasic, Dragana

2016-12-25

The optimal bio-functionalization of magnetic particles is essential for developing magnetic particle-based bioassays. Whereas functionalization with antibodies is generally well established, immobilization of DNA probes, such as aptamers, is not yet fully explored. In this work, four different types of commercially available magnetic particles, coated with streptavidin, maleimide or carboxyl groups, were evaluated for their surface coverage with aptamer bioreceptors, efficiency in capturing target protein and non-specific protein adsorption on their surface. A recently developed aptamer against the peanut allergen, Ara h 1 protein, was used as a model system. Conjugation of biotinylated Ara h 1 aptamer to the streptavidin particles led to the highest surface coverage, whereas the coverage of maleimide particles was 25% lower. Carboxylated particles appeared to be inadequate for DNA functionalization. Streptavidin particles also showed the greatest target capturing efficiency, comparable to the one of particles functionalized with anti-Ara h 1 antibody. The performance of streptavidin particles was additionally tested in a sandwich assay with the aptamer as a capture receptor on the particle surface. While the limit of detection obtained was comparable to the same assay system with antibody as capture receptor, it was superior to previously reported values using the same aptamer in similar assay schemes with different detection platforms. These results point to the promising application of the Ara h 1 aptamer-functionalized particles in bioassay development. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimization of magnetoresistive sensor current for on-chip magnetic bead detection using the sensor self-field

DEFF Research Database (Denmark)

Henriksen, Anders Dahl; Rizzi, Giovanni; Østerberg, Frederik Westergaard

2015-01-01

We investigate the self-heating of magnetoresistive sensors used for measurements on magnetic beads in magnetic biosensors. The signal from magnetic beads magnetized by the field due to the sensor bias current is proportional to the bias current squared. Therefore, we aim to maximize the bias...... current while limiting the sensor self-heating. We systematically characterize and model the Joule heating of magnetoresistive sensors with different sensor geometries and stack compositions. The sensor heating is determined using the increase of the sensor resistance as function of the bias current......, thus the heat conductance is proportional to the sensor area and inversely proportional to the oxide thickness. This simple heat conductance determines the relationship between bias current and sensor temperature, and we show that View the MathML source25μm wide sensor on a View the MathML source1μm...

Establishing a novel automated magnetic bead-based method for the extraction of DNA from a variety of forensic samples.

Science.gov (United States)

Witt, Sebastian; Neumann, Jan; Zierdt, Holger; Gébel, Gabriella; Röscheisen, Christiane

2012-09-01

Automated systems have been increasingly utilized for DNA extraction by many forensic laboratories to handle growing numbers of forensic casework samples while minimizing the risk of human errors and assuring high reproducibility. The step towards automation however is not easy: The automated extraction method has to be very versatile to reliably prepare high yields of pure genomic DNA from a broad variety of sample types on different carrier materials. To prevent possible cross-contamination of samples or the loss of DNA, the components of the kit have to be designed in a way that allows for the automated handling of the samples with no manual intervention necessary. DNA extraction using paramagnetic particles coated with a DNA-binding surface is predestined for an automated approach. For this study, we tested different DNA extraction kits using DNA-binding paramagnetic particles with regard to DNA yield and handling by a Freedom EVO(®)150 extraction robot (Tecan) equipped with a Te-MagS magnetic separator. Among others, the extraction kits tested were the ChargeSwitch(®)Forensic DNA Purification Kit (Invitrogen), the PrepFiler™Automated Forensic DNA Extraction Kit (Applied Biosystems) and NucleoMag™96 Trace (Macherey-Nagel). After an extensive test phase, we established a novel magnetic bead extraction method based upon the NucleoMag™ extraction kit (Macherey-Nagel). The new method is readily automatable and produces high yields of DNA from different sample types (blood, saliva, sperm, contact stains) on various substrates (filter paper, swabs, cigarette butts) with no evidence of a loss of magnetic beads or sample cross-contamination. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Targeting to carcinoma cells with chitosan- and starch-coated magnetic nanoparticles for magnetic hyperthermia.

Science.gov (United States)

Kim, Dong-Hyun; Kim, Kyoung-Nam; Kim, Kwang-Mahn; Lee, Yong-Keun

2009-01-01

The delivery of hyperthermic thermoseeds to a specific target site with minimal side effects is an important challenge in targeted hyperthermia, which employs magnetic method and functional polymers. An external magnetic field is used to control the site-specific targeting of the magnetic nanoparticles. Polymer-coated magnetic nanoparticles can confer a higher affinity to the biological cell membranes. In this study, uncoated, chitosan-coated, and starch-coated magnetic nanoparticles were synthesized for use as a hyperthermic thermoseed. Each sample was examined with respect to their applications to hyperthermia using XRD, VSM, and FTIR. In addition, the temperature changes under an alternating magnetic field were observed. As in vitro tests, the magnetic responsiveness of chitosan- and starch-coated magnetite was determined by a simple blood vessel model under various intensities of magnetic field. L929 normal cells and KB carcinoma cells were used to examine the cytotoxicity and affinity of each sample using the MTT method. The chitosan-coated magnetic nanoparticles generated a higher DeltaT of 23 degrees C under an AC magnetic field than the starch-coated magnetite, and the capturing rate of the particles was 96% under an external magnetic field of 0.4 T. The highest viability of L929 cells was 93.7%. Comparing the rate of KB cells capture with the rate of L929 cells capture, the rate of KB cells capture relatively increased with 10.8% in chitosan-coated magnetic nanoparticles. Hence, chitosan-coated magnetic nanoparticles are biocompatible and have a selective affinity to KB cells. The targeting of magnetic nanoparticles in hyperthermia was improved using a controlled magnetic field and a chitosan-coating. Therefore, chitosan-coated magnetic nanoparticles are expected to be promising materials for use in magnetic targeted hyperthermia. 2008 Wiley Periodicals, Inc.

Fibrous polymer grafted magnetic chitosan beads with strong poly(cation-exchange) groups for single step purification of lysozyme.

Science.gov (United States)

Bayramoglu, Gulay; Tekinay, Turgay; Ozalp, V Cengiz; Arica, M Yakup

2015-05-15

Lysozyme is an important polypetide used in medical and food applications. We report a novel magnetic strong cation exchange beads for efficient purification of lysozyme from chicken egg white. Magnetic chitosan (MCHT) beads were synthesized via phase inversion method, and then grafted with poly(glycidyl methacrylate) (p(GMA)) via the surface-initiated atom transfer radical polymerization (SI-ATRP). Epoxy groups of the grafted polymer, were modified into strong cation-exchange groups (i.e., sulfonate groups) in the presence of sodium sulfite. The MCTH and MCTH-g-p(GMA)-SO3H beads were characterized by ATR-FTIR, SEM, and VSM. The sulphonate groups content of the modified MCTH-g-p(GMA)-4 beads was found to be 0.53mmolg(-1) of beads by the potentiometric titration method. The MCTH-g-p(GMA)-SO3H beads were first used as an ion-exchange support for adsorption of lysozyme from aqueous solution. The influence of different experimental parameters such as pH, contact time, and temperature on the adsorption process was evaluated. The maximum adsorption capacity was found to be 208.7mgg(-1) beads. Adsorption of lysozyme on the MCTH-g-p(GMA)-SO3H beads fitted to Langmuir isotherm model and followed the pseudo second-order kinetic. More than 93% of the adsorbed lysozyme was desorbed using Na2CO3 solution (pH 11.0). The purity of the lysozyme was checked by HPLC and SDS gel electrophoresis. In addition, the MCTH-g-p(GMA)-SO3H beads prepared in this work showed promising potential for separation of various anionic molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of the Effect of Psyllium on the Viability of Lactobacillus Acidophilus in Alginate-Polyl Lysine Beads.

Science.gov (United States)

Esmaeilzadeh, Jaleh; Nazemiyeh, Hossein; Maghsoodi, Maryam; Lotfipour, Farzaneh

2016-09-01

Purpose: Psylliumseeds are used in traditional herbal medicine to treat various disorders. Moreover, as a soluble fiber, psyllium has potential to stimulate bacterial growth in digestive system. We aimed to substitute alkali-extractable polysaccharides of psyllium for alginate in beads with second coat of poly-l-lysine to coat Lactobacillus acidophilus. Methods: Beads were prepared using extrusion technique. Poly-l-lysine as second coat was incorporated on optimum alginate/psyllium beads using immersion technique. Beads were characterized in terms of size, encapsulation efficiency, integrity and bacterial survival in harsh conditions. Results: Beads with narrow size distribution ranging from 1.85 ± 0.05 to 2.40 ± 0.18 mm with encapsulation efficiency higher than 96% were achieved. Psyllium concentrations in beads did not produce constant trend in bead sizes. Surface topography by SEM showed that substitution of psyllium enhanced integrity of obtained beads. Psyllium successfully protected the bacteria against acidic condition and lyophilization equal to alginate in the beads. Better survivability with beads of alginate/psyllium-poly-l-lysine was achieved with around 2 log rise in bacterial count in acid condition compared to the corresponding single coat beads. Conclusion: Alginate/psyllium (1:2) beads with narrow size distribution and high encapsulation efficiency of the bacteria have been achieved. Presence of psyllium produced a much smoother and integrated surface texture for the beads with sufficient protection of the bacteria against acidic condition as much as alginate. Considering the health benefits of psyllium and its prebiotic activity, psyllium can be beneficially replaced in part for alginate in probiotic coating.

Efficacy of polymer coating of probiotic beads suspended in pressurized and pasteurized longan juices on the exposure to simulated gastrointestinal environment.

Science.gov (United States)

Chaikham, Pittaya; Apichartsrangkoon, Arunee; George, Trevor; Jirarattanarangsri, Wachira

2013-11-01

Alginate-coated Lactobacillus acidophilus LA5 or Lactobacillus casei 01 was recoated with either 0.1-0.5% (w/v) alginate or 0.05-0.15% (w/v) poly-L-lysine (PLL) plus 0.2% (w/v) alginate or 5-15% (w/v) gelatin, after which they were determined for survivability in gastric or bile longan juices. The morphology of encapsulated probiotic cells illustrated that recoated beads with 0.5% alginate showed a more compact surface and a greater protective effect than other recoating materials. The recoated beads with 0.5% alginate and 0.05-0.15% PLL plus 0.2% alginate of both strains showed the highest viability in gastric longan juice. In bile longan juice, only 0.5% alginate showed the best protection for both recoated beads. When considering the storage stability, encapsulated L. acidophilus LA5 exhibited a higher viable count than those of the free cells, whereas L. casei 01 showed equivalent viability of both free and double-coated cells. Based on the impact of pressurization or pasteurization, both processed juices gave rise to equivalent survivability of the probiotic cells during storage.

Cermet coatings for magnetic fusion reactors

International Nuclear Information System (INIS)

Smith, M.F.; Whitley, J.B.; McDonald, J.M.

1984-01-01

Cermet coatings consisting of SiC particles in an aluminum matrix were produced by a low pressure chamber plasma spray process. Properties of these coatings are being investigated to evaluate their suitability for use in the next generation of magnetic confinement fusion reactors. Although this preliminary study has focused primarily upon SiC-Al cermets, the deposition process can be adapted to other ceramic-metal combinations. Potential applications for cermet coatings in magnetic fusion devices are presented along with experimental results from thermal tests of candidate coatings. (Auth.)

Magnetostriction in glass-coated magnetic microwires

International Nuclear Information System (INIS)

Zhukov, A.; Zhukova, V.; Blanco, J.M.; Cobeno, A.F.; Vazquez, M.; Gonzalez, J

2003-01-01

The hysteretic magnetic properties of glass coated magnetic microwires depend on the magnetostriction constant: Co-rich microwires with negative magnetostriction constant present an almost non-hysteretic loop with relatively high magnetic anisotropy field up to around 8 kA/m. In contrast, Fe-rich microwires with positive magnetostriction show rectangular hysteresis loops with switching field depending on diameter of the metallic nucleus and the thickness of the glass coating. The softest magnetic properties, such as large magnetic permeability, are observed in nearly zero magnetostrictive alloys. It is then obvious that the experimental determination of the saturation magnetostriction λ s of glass-coated microwires is very important to predict their magnetic behaviour. Different methods for the determination of the saturation magnetostriction λ s of tiny glass coated microwires have been reviewed and compared in this manuscript. Small angle magnetization rotation (SAMR) method and change of the giant magneto-impedance spectrum under applied stress have been employed in nearly zero magnetostrictive in as-prepared and current annealed glass-covered microwires. The conditions of applicability of these methods to the microwires have been analysed, taking into account the domain structure expected for vanishing magnetostriction constant of the metallic nucleus. These different techniques give similar saturation magnetostriction constant values. Heat treatment results in a significant change of λ s

Selection and Characterization of Single Stranded DNA Aptamers for the Hormone Abscisic Acid

Science.gov (United States)

Gonzalez, Victor M.; Millo, Enrico; Sturla, Laura; Vigliarolo, Tiziana; Bagnasco, Luca; Guida, Lucrezia; D'Arrigo, Cristina; De Flora, Antonio; Salis, Annalisa; Martin, Elena M.; Bellotti, Marta; Zocchi, Elena

2013-01-01

The hormone abscisic acid (ABA) is a small molecule involved in pivotal physiological functions in higher plants. Recently, ABA has been also identified as an endogenous hormone in mammals, regulating different cell functions including inflammatory processes, stem cell expansion, insulin release, and glucose uptake. Aptamers are short, single-stranded (ss) oligonucleotidesable to recognize target molecules with high affinity. The small size of the ABA molecule represented a challenge for aptamer development and the aim of this study was to develop specific anti-ABA DNA aptamers. Biotinylated abscisic acid (bio-ABA) was immobilized on streptavidin-coated magnetic beads. DNA aptamers against bio-ABA were selected with 7 iterative rounds of the systematic evolution of ligands by exponential enrichment method (SELEX), each round comprising incubation of the ABA-binding beads with the ssDNA sequences, DNA elution, electrophoresis, and polymerase chain reaction (PCR) amplification. The PCR product was cloned and sequenced. The binding affinity of several clones was determined using bio-ABA immobilized on streptavidin-coated plates. Aptamer 2 and aptamer 9 showed the highest binding affinity, with dissociation constants values of 0.98±0.14 μM and 0.80±0.07 μM, respectively. Aptamers 2 and 9 were also able to bind free, unmodified ABA and to discriminate between different ABA enantiomers and isomers. Our findings indicate that ssDNA aptamers can selectively bind ABA and could be used for the development of ABA quantitation assays. PMID:23971905

A novel automated device for rapid nucleic acid extraction utilizing a zigzag motion of magnetic silica beads

International Nuclear Information System (INIS)

Yamaguchi, Akemi; Matsuda, Kazuyuki; Uehara, Masayuki; Honda, Takayuki; Saito, Yasunori

2016-01-01

We report a novel automated device for nucleic acid extraction, which consists of a mechanical control system and a disposable cassette. The cassette is composed of a bottle, a capillary tube, and a chamber. After sample injection in the bottle, the sample is lysed, and nucleic acids are adsorbed on the surface of magnetic silica beads. These magnetic beads are transported and are vibrated through the washing reagents in the capillary tube under the control of the mechanical control system, and thus, the nucleic acid is purified without centrifugation. The purified nucleic acid is automatically extracted in 3 min for the polymerase chain reaction (PCR). The nucleic acid extraction is dependent on the transport speed and the vibration frequency of the magnetic beads, and optimizing these two parameters provided better PCR efficiency than the conventional manual procedure. There was no difference between the detection limits of our novel device and that of the conventional manual procedure. We have already developed the droplet-PCR machine, which can amplify and detect specific nucleic acids rapidly and automatically. Connecting the droplet-PCR machine to our novel automated extraction device enables PCR analysis within 15 min, and this system can be made available as a point-of-care testing in clinics as well as general hospitals. - Highlights: • Automatic nucleic acid extraction is performed in 3 min. • Zigzag motion of magnetic silica beads yields rapid and efficient extraction. • The present our device provides better performance than the conventional procedure.

[Development of new magnetic bead separation and purification instrument].

Science.gov (United States)

Xu, Yingyuan; Chen, Yi

2014-05-01

The article describes the development of new magnetic bead separation and purification instrument. The main application of the instrument is to capture tubercle bacillus from sputum. It is a pretreatment instrument and provides a new platform to help doctors to diagnose bacillary phthisis. Not only could it be used for tubercle bacillus capturing, but also for gene, protein and cell separating and purification. Because the controller of the instrument is 16-bit single chip microcomputer, the cost could be greatly reduced and it will be widely used in China.

Integration of antibody by surface functionalization of graphite-encapsulated magnetic beads using ammonia gas plasma technology for capturing influenza A virus.

Science.gov (United States)

Sakudo, Akikazu; Chou, Han; Ikuta, Kazuyoshi; Nagatsu, Masaaki

2015-05-01

Antibody-integrated magnetic beads have been functionalized for influenza A virus capture. First, ammonia plasma produced by a radio frequency power source was reacted with the surface of graphite-encapsulated magnetic beads to introduce amino groups. Anti-influenza A virus hemagglutinin antibody was then anchored by its surface sulfide groups to the amino groups on the beads via N-succinimidyl 3-(2-pyridyldithio) propionate. After incubation with influenza A virus, adsorption of the virus to the beads was confirmed by immunochromatography, polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and inoculation of chicken embryonated eggs, indicating that virus infectivity is maintained and that the proposed method is useful for the enhanced detection and isolation of influenza A virus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chitosan coated alginate-xanthan gum bead enhanced pH and thermotolerance of Lactobacillus plantarum LAB12.

Science.gov (United States)

Fareez, Ismail M; Lim, Siong Meng; Mishra, Rakesh K; Ramasamy, Kalavathy

2015-01-01

The vulnerability of probiotics at low pH and high temperature has limited their optimal use as nutraceuticals. This study addressed these issues by adopting a physicochemical driven approach of incorporating Lactobacillus plantarum LAB12 into chitosan (Ch) coated alginate-xanthan gum (Alg-XG) beads. Characterisation of Alg-XG-Ch, which elicited little effect on bead size and polydispersity, demonstrated good miscibility with improved bead surface smoothness and L. plantarum LAB12 entrapment when compared to Alg, Alg-Ch and Alg-XG. Sequential incubation of Alg-XG-Ch in simulated gastric juice and intestinal fluid yielded high survival rate of L. plantarum LAB12 (95%) at pH 1.8 which in turn facilitated sufficient release of probiotics (>7 log CFU/g) at pH 6.8 in both time- and pH-dependent manner. Whilst minimising viability loss at 75 and 90 °C, Alg-XG-Ch improved storage durability of L. plantarum LAB12 at 4 °C. The present results implied the possible use of L. plantarum LAB12 incorporated in Alg-XG-Ch as new functional food ingredient with health claims. Copyright © 2014 Elsevier B.V. All rights reserved.

In vitro transcription of a torsionally constrained template

DEFF Research Database (Denmark)

Bentin, Thomas; Nielsen, Peter E

2002-01-01

of torsionally constrained DNA by free RNAP. We asked whether or not a newly synthesized RNA chain would limit transcription elongation. For this purpose we developed a method to immobilize covalently closed circular DNA to streptavidin-coated beads via a peptide nucleic acid (PNA)-biotin conjugate in principle...

Polyvinyl-alcohol-based magnetic beads for rapid and efficient separation of specific or unspecific nucleic acid sequences

International Nuclear Information System (INIS)

Oster, J.; Parker, Jeffrey; Brassard, Lothar

2001-01-01

The versatile application of polyvinyl-alcohol-based magnetic M-PVA beads is demonstrated in the separation of genomic DNA, sequence specific nucleic acid purification, and binding of bacteria for subsequent DNA extraction and detection. It is shown that nucleic acids can be obtained in high yield and purity using M-PVA beads, making sample preparation efficient, fast and highly adaptable for automation processes

Yersinia pestis detection by loop-mediated isothermal amplification combined with magnetic bead capture of DNA

Directory of Open Access Journals (Sweden)

Na Feng

Full Text Available ABSTRACT We developed a loop-mediated isothermal amplification (LAMP assay for the detection of Y. pestis by targeting the 3a sequence on chromosome. All 11 species of the genus Yersinia were used to evaluate the specificity of LAMP and PCR, demonstrating that the primers had a high level of specificity. The sensitivity of LAMP or PCR was 2.3 or 23 CFU for pure culture, whereas 2.3 × 104 or 2.3 × 106 CFU for simulated spleen and lung samples. For simulated liver samples, the sensitivity of LAMP was 2.3 × 106 CFU, but PCR was negative at the level of 2.3 × 107 CFU. After simulated spleen and lung samples were treated with magnetic beads, the sensitivity of LAMP or PCR was 2.3 × 103 or 2.3 × 106 CFU, whereas 2.3 × 105 or 2.3 × 107 CFU for magnetic bead-treated liver samples. These results indicated that some components in the tissues could inhibit LAMP and PCR, and liver tissue samples had a stronger inhibition to LAMP and PCR than spleen and lung tissue samples. LAMP has a higher sensitivity than PCR, and magnetic bead capture of DNAs could remarkably increase the sensitivity of LAMP. LAMP is a simple, rapid and sensitive assay suitable for application in the field or poverty areas.

Magnet-induced temporary superhydrophobic coatings from one-pot synthesized hydrophobic magnetic nanoparticles.

Science.gov (United States)

Fang, Jian; Wang, Hongxia; Xue, Yuhua; Wang, Xungai; Lin, Tong

2010-05-01

In this paper, we report on the production of superhydrophobic coatings on various substrates (e.g., glass slide, silicon wafer, aluminum foil, plastic film, nanofiber mat, textile fabrics) using hydrophobic magnetic nanoparticles and a magnet-assembly technique. Fe(3)O(4) magnetic nanoparticles functionalized with a thin layer of fluoroalkyl silica on the surface were synthesized by one-step coprecipitation of Fe(2+)/Fe(3+) under an alkaline condition in the presence of a fluorinated alkyl silane. Under a magnetic field, the magnetic nanoparticles can be easily deposited on any solid substrate to form a thin superhydrophobic coating with water contact angle as high as 172 degrees , and the surface superhydrophobicity showed very little dependence on the substrate type. The particulate coating showed reasonable durability because of strong aggregation effect of nanoparticles, but the coating layer can be removed (e.g., by ultrasonication) to restore the original surface feature of the substrates. By comparison, the thin particle layer deposited under no magnetic field showed much lower hydrophobicity. The main reason for magnet-induced superhydrophobic surfaces is the formation of nano- and microstructured surface features. Such a magnet-induced temporary superhydrophobic coating may have wide applications in electronic, biomedical, and defense-related areas.

Fluctuations of cytoskeleton-bound microbeads-the effect of bead-receptor binding dynamics

International Nuclear Information System (INIS)

Metzner, C; Raupach, C; Mierke, C T; Fabry, B

2010-01-01

The cytoskeleton (CSK) of living cells is a crosslinked fiber network, subject to ongoing biochemical remodeling processes that can be visualized by tracking the spontaneous motion of CSK-bound microbeads. The bead motion is characterized by anomalous diffusion with a power-law time evolution of the mean square displacement (MSD), and can be described as a stochastic transport process with apparent diffusivity D and power-law exponent β: MSD ∼ D (t/t 0 ) β . Here we studied whether D and β change with the time that has passed after the initial bead-cell contact, and whether they are sensitive to bead coating (fibronectin, integrin antibodies, poly-L-lysine, albumin) and bead size (0.5-4.5 μm). The measurements are interpreted in the framework of a simple model that describes the bead as an overdamped particle coupled to the fluctuating CSK network by an elastic spring. The viscous damping coefficient characterizes the degree of bead internalization into the cell, and the spring constant characterizes the strength of the binding of the bead to the CSK. The model predicts distinctive signatures of the MSD that change with time as the bead couples more tightly to the CSK and becomes internalized. Experimental data show that the transition from the unbound to the tightly bound state occurs in an all-or-nothing manner. The time point of this transition shows considerable variability between individual cells (2-30 min) and depends on the bead size and bead coating. On average, this transition occurs later for smaller beads and beads coated with ligands that trigger the formation of adhesion complexes (fibronectin, integrin antibodies). Once the bead is linked to the CSK, however, the ligand type and bead size have little effect on the MSD. On longer timescales of several hours after bead addition, smaller beads are internalized into the cell more readily, leading to characteristic changes in the MSD that are consistent with increased viscous damping by the

Sodium lauryl sulfate impedes drug release from zinc-crosslinked alginate beads: switching from enteric coating release into biphasic profiles.

Science.gov (United States)

Taha, Mutasem O; Nasser, Wissam; Ardakani, Adel; Alkhatib, Hatim S

2008-02-28

The aim of this research is to investigate the effects of sodium lauryl sulfate (SLS) on ionotropically cross-linked alginate beads. Different levels of SLS were mixed with sodium alginate and chlorpheniramine maleate (as loaded model drug). The resulting viscous solutions were dropped onto aqueous solutions of zinc or calcium ions for ionotropic curing. The generated beads were assessed by their drug releasing profiles, infrared and differential scanning colorimetery (DSC) traits. SLS was found to exert profound concentration-dependent impacts on the characteristics of zinc-crosslinked alginate beads such that moderate modifications in the levels of SLS switched drug release from enteric coating-like behavior to a biphasic release modifiable to sustained-release by the addition of minute amounts of xanthan gum. Calcium cross-linking failed to reproduce the same behavior, probably due to the mainly ionic nature of calcium-carboxylate bonds compared to the coordinate character of their zinc-carboxylate counterparts. Apparently, moderate levels of SLS repel water penetration into the beads, and therefore minimize chlorpheniramine release. However, higher SLS levels seem to discourage polymeric cross-linking and therefore allow biphasic drug release.

Development of liposomes entrapped in alginate beads for the treatment of colorectal cancer.

Science.gov (United States)

Bansal, Divya; Gulbake, Arvind; Tiwari, Jyoti; Jain, Sanjay K

2016-01-01

Folic Acid conjugated liposomes encapsulating Oxaliplatin (L-OHP) were entrapped in alginate beads and further coated with Eudragit-S-100 for effective delivery to colon tumors. Liposomes were prepared by cast film method and folic acid was coupled on the surface of liposomes. They were further entrapped in alginate beads which were Eudragit coated for degradation in the colonic region. The prepared beads were characterized for shape and surface morphology, percentage entrapment efficiency and drug release studies. The in vitro drug release was investigated using a USP dissolution paddle type apparatus in different simulated gastrointestinal fluids. In vivo studies of the beads containing free drug, folic acid coupled and uncoupled liposomes bearing L-OHP was administered orally at the dose of 10mg L-OHP/kg body weight to tumor bearing NUDE/SCID mice. γ-Scintigraphic study showed that Eudragit coated alginate beads entered into the colon of Balb/c mice between 4.20 and 4.50h after oral administration. In vivo data showed that folic acid coupled liposomes entrapped in alginate beads delivered 2.82 ± 0.58 and 21.52 ± 2.76 μg L-OHP/g tissues in the colon and tumor after 12h, reflecting its targeting potential to colon and tumor. The results clearly demonstrate that Eudragit coated calcium alginate beads bearing folic acid coupled liposome can be used as a prospective carrier for drug delivery to colon specific tumor. Copyright © 2015 Elsevier B.V. All rights reserved.

The synthesis, magnetic purification and evaluation of 99mTc-labeled microbubbles

International Nuclear Information System (INIS)

Lazarova, Neva; Causey, Patrick W.; Lemon, Jennifer A.; Czorny, Shannon K.; Forbes, John R.; Zlitni, Aimen; Genady, Afaf; Foster, F. Stuart; Valliant, John F.

2011-01-01

Introduction: Ultrasound (US) contrast agents based on microbubbles (MBs) are being investigated as platforms for drug and gene delivery. A methodology for determining the distribution and fate of modified MBs quantitatively in vivo can be achieved by tagging MBs directly with 99m Tc. This creates the opportunity to employ dual-modality imaging using both US and small animal SPECT along with quantitative ex vivo tissue counting to evaluate novel MB constructs. Methods: A 99m Tc-labeled biotin derivative ( 99m TcL1) was prepared and incubated with streptavidin-coated MBs. The 99m Tc-labeled bubbles were isolated using a streptavidin-coated magnetic-bead purification strategy that did not disrupt the MBs. A small animal scintigraphic/CT imaging study as well as a quantitative biodistribution study was completed using 99m TcL1 and 99m Tc-labeled bubbles in healthy C57Bl-6 mice. Results: The imaging and biodistribution data showed rapid accumulation and retention of 99m Tc-MBs in the liver (68.2±6.6 %ID/g at 4 min; 93.3±3.2 %ID/g at 60 min) and spleen (214.2±19.7 %ID/g at 4 min; 213.4±19.7 %ID/g at 60 min). In contrast, 99m TcL1 accumulated in multiple organs including the small intestine (22.5±3.6 %ID/g at 4 min; 83.4±5.9 %ID/g at 60 min) and bladder (184.0±88.1 %ID/g at 4 min; 24.2±17.7 %ID/g at 60 min). Conclusion: A convenient means to radiolabel and purify MBs was developed and the distribution of the labeled products determined. The result is a platform which can be used to assess the pharmacokinetics and fate of novel MB constructs both regionally using US and throughout the entire subject in a quantitative manner by employing small animal SPECT and tissue counting.

Uptake of magnetic nanoparticles into cells for cell tracking

International Nuclear Information System (INIS)

Becker, Christiane; Hodenius, Michael; Blendinger, Gitta; Sechi, Antonio; Hieronymus, Thomas; Mueller-Schulte, Detlef; Schmitz-Rode, Thomas; Zenke, Martin

2007-01-01

A challenge for future applications in nanotechnology is the functional integration of nano-sized materials into cellular structures. Here we investigated superparamagnetic Fe 3 O 4 iron oxide nanoparticles coated with a lipid bilayer for uptake into cells and for targeting subcellular compartments. It was found that magnetic nanoparticles (MNPs) are effectively taken up into cells and make cells acquire magnetic activity. Biotin-conjugated MNPs were further functionalized by binding of the fluorescent tag streptavidin-fluorescein isothiocyanate (FITC) and, following uptake into cells, shown to confer magnetic activity and fluorescence labeling. Such FITC-MNPs were localized in the lysosomal compartment of cells which suggests a receptor-mediated uptake mechanism

Magnetic Beads-Based Sensor with Tailored Sensitivity for Rapid and Single-Step Amperometric Determination of miRNAs

Directory of Open Access Journals (Sweden)

Eva Vargas

2017-11-01

Full Text Available This work describes a sensitive amperometric magneto-biosensor for single-step and rapid determination of microRNAs (miRNAs. The developed strategy involves the use of direct hybridization of the target miRNA (miRNA-21 with a specific biotinylated DNA probe immobilized on streptavidin-modified magnetic beads (MBs, and labeling of the resulting heteroduplexes with a specific DNA–RNA antibody and the bacterial protein A (ProtA conjugated with an horseradish peroxidase (HRP homopolymer (Poly-HRP40 as an enzymatic label for signal amplification. Amperometric detection is performed upon magnetic capture of the modified MBs onto the working electrode surface of disposable screen-printed carbon electrodes (SPCEs using the H2O2/hydroquinone (HQ system. The magnitude of the cathodic signal obtained at −0.20 V (vs. the Ag pseudo-reference electrode demonstrated linear dependence with the concentration of the synthetic target miRNA over the 1.0 to 100 pM range. The method provided a detection limit (LOD of 10 attomoles (in a 25 μL sample without any target miRNA amplification in just 30 min (once the DNA capture probe-MBs were prepared. This approach shows improved sensitivity compared with that of biosensors constructed with the same anti-DNA–RNA Ab as capture instead of a detector antibody and further labeling with a Strep-HRP conjugate instead of the Poly-HRP40 homopolymer. The developed strategy involves a single step working protocol, as well as the possibility to tailor the sensitivity by enlarging the length of the DNA/miRNA heteroduplexes using additional probes and/or performing the labelling with ProtA conjugated with homopolymers prepared with different numbers of HRP molecules. The practical usefulness was demonstrated by determination of the endogenous levels of the mature target miRNA in 250 ng raw total RNA (RNAt extracted from human mammary epithelial normal (MCF-10A and cancer (MCF-7 cells and tumor tissues.

Silver doped hydroxyapatite coatings by sacrificial anode deposition under magnetic field.

Science.gov (United States)

Swain, S; Rautray, T R

2017-09-13

Uniform distribution of silver (Ag) in the hydroxyapatite (HA) coated Ti surface has been a concern for which an attempt has been made to dope Ag in HA coating with and without magnetic field. Cathodic deposition technique was employed to coat Ag incorporated hydroxyapatite coating using a sacrificial silver anode method by using NdFeB bar magnets producing 12 Tesla magnetic field. While uniform deposition of Ag was observed in the coatings under magnetic field, dense coating was evident in the coating without magnetic field conditions. Uniformly distributed Ag incorporated HA in the present study has potential to fight microorganism while providing osseoconduction properties of the composite coating.

Creating nanoshell on the surface of titanium hydride bead

Directory of Open Access Journals (Sweden)

PAVLENKO Vyacheslav Ivanovich

2016-12-01

Full Text Available The article presents data on the modification of titanium hydride bead by creating titanium nanoshell on its surface by ion-plasma vacuum magnetron sputtering. To apply titanium nanoshell on the titanium hydride bead vacuum coating plant of multifunctional nanocomposite coatings QVADRA 500 located in the center of high technology was used. Analysis of the micrographs of the original surface of titanium hydride bead showed that the microstructure of the surface is flat, smooth, in addition the analysis of the microstructure of material surface showed the presence of small porosity, roughness, mainly cavities, as well as shallow longitudinal cracks. The presence of oxide film in titanium hydride prevents the free release of hydrogen and fills some micro-cracks on the surface. Differential thermal analysis of both samples was conducted to determine the thermal stability of the initial titanium hydride bead and bead with applied titanium nanoshell. Hydrogen thermal desorption spectra of the samples of the initial titanium hydride bead and bead with applied titanium nanoshell show different thermal stability of compared materials in the temperature range from 550 to 860о C. Titanium nanoshells applied in this way allows increasing the heat resistance of titanium hydride bead – the temperature of starting decomposition is 695о C and temperature when decomposition finishes is more than 1000о C. Modified in this way titanium hydride bead can be used as a filler in the radiation protective materials used in the construction or upgrading biological protection of nuclear power plants.

Decoupling internalization, acidification and phagosomal-endosomal/lysosomal fusion during phagocytosis of InlA coated beads in epithelial cells.

Directory of Open Access Journals (Sweden)

Craig D Blanchette

Full Text Available BACKGROUND: Phagocytosis has been extensively examined in 'professional' phagocytic cells using pH sensitive dyes. However, in many of the previous studies, a separation between the end of internalization, beginning of acidification and completion of phagosomal-endosomal/lysosomal fusion was not clearly established. In addition, very little work has been done to systematically examine phagosomal maturation in 'non-professional' phagocytic cells. Therefore, in this study, we developed a simple method to measure and decouple particle internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion in Madin-Darby Canine Kidney (MDCK and Caco-2 epithelial cells. METHODOLOGY/PRINCIPAL FINDINGS: Our method was developed using a pathogen mimetic system consisting of polystyrene beads coated with Internalin A (InlA, a membrane surface protein from Listeria monocytogenes known to trigger receptor-mediated phagocytosis. We were able to independently measure the rates of internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion in epithelial cells by combining the InlA-coated beads (InlA-beads with antibody quenching, a pH sensitive dye and an endosomal/lysosomal dye. By performing these independent measurements under identical experimental conditions, we were able to decouple the three processes and establish time scales for each. In a separate set of experiments, we exploited the phagosomal acidification process to demonstrate an additional, real-time method for tracking bead binding, internalization and phagosomal acidification. CONCLUSIONS/SIGNIFICANCE: Using this method, we found that the time scales for internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion ranged from 23-32 min, 3-4 min and 74-120 min, respectively, for MDCK and Caco-2 epithelial cells. Both the static and real-time methods developed here are expected to be readily and broadly applicable, as they simply

Heat generation ability in AC magnetic field of nano MgFe2O4-based ferrite powder prepared by bead milling

International Nuclear Information System (INIS)

Hirazawa, Hideyuki; Aono, Hiromichi; Naohara, Takashi; Maehara, Tsunehiro; Sato, Mitsunori; Watanabe, Yuji

2011-01-01

Nanosized MgFe 2 O 4 -based ferrite powder having heat generation ability in an AC magnetic field was prepared by bead milling and studied for thermal coagulation therapy applications. The crystal size and the particle size significantly decreased by bead milling. The heat generation ability in an AC magnetic field improved with the milling time, i.e. a decrease in crystal size. However, the heat generation ability decreased for excessively milled samples with crystal sizes of less than 5.5 nm. The highest heat ability (ΔT=34 o C) in the AC magnetic field (370 kHz, 1.77 kA/m) was obtained for fine MgFe 2 O 4 powder having a ca. 6 nm crystal size (the samples were milled for 6-8 h using 0.1 mm φ beads). The heat generation of the samples was closely related to hysteresis loss, a B-H magnetic property. The reason for the high heat generation properties of the samples milled for 6-8 h using 0.1 mm φ beads was ascribed to the increase in hysteresis loss by the formation of a single domain. Moreover, the improvement in heating ability was obtained by calcination of the bead-milled sample at low temperature. In this case, the maximum heat generation (ΔT=41 o C) ability was obtained for a ca. 11 nm crystal size sample was prepared by crystal growth during the sample calcination. On the other hand, the ΔT value for Mg 0.5 Ca 0.5 Fe 2 O 4 was synthesized using a reverse precipitation method decreased by bead milling. - Research Highlights: →The crystal and particle size for MgFe 2 O 4 based ferrite were decreased by bead milling. →The highest heat ability was obtained for MgFe 2 O 4 having a ca. 6 nm crystal size. →This high heat generation ability was ascribed to the increase in hysteresis loss. →Hysteresis loss was increased by the formation of a single domain.

Connecting DNA origami structures using the biotin- streptavidin ...

African Journals Online (AJOL)

Aghomotsegin

carbon nanotubes on DNA origami. In order to reconfigure DNA origami pliers, Kuzuya (Kuzuya et al.,. 2011) and colleagues used the strong binding biotin- streptavidin interaction. All these researchers made use of the biotin- streptavidin interaction to functionalize the DNA strand or. DNA origami structures. In this work, we ...

Clinical feasibility of two-step streptavidin/111In-biotin scintigraphy in patients with suspected vertebral osteomyelitis

International Nuclear Information System (INIS)

Lazzeri, Elena; Erba, Paola A.; Volterrani, Duccio; Bottoni, Antonio; Mariani, Giuliano; Pauwels, Ernest K.J.; Manca, Mario; Bodei, Lisa; Trippi, Donatella; Cristofani, Renza; Consoli, Vincenzo; Palestro, Christopher J.

2004-01-01

Streptavidin accumulates at sites of inflammation and infection as a result of increased capillary permeability. In addition to being utilised by bacteria for their own growth, biotin forms a stable, high-affinity non-covalent complex with avidin. The objective of this investigation was to determine the diagnostic performance of two-step streptavidin/ 111 In-biotin imaging for evaluating patients with suspected vertebral osteomyelitis. We evaluated 55 consecutive patients with suspected vertebral osteomyelitis (34 women and 21 men aged 27-86 years), within 2 weeks after the onset of clinical symptoms. Thirty-two of the patients underwent magnetic resonance imaging (MRI) and 24, computed tomography (CT). DTPA-conjugated biotin was radiolabelled by incubating 500 μg of DTPA-biotin with 111 MBq of 111 In-chloride. Two-step scintigraphy was performed by first infusing 3 mg streptavidin intravenously, followed 4 h later by 111 In-biotin. Imaging was begun 60 min later. Streptavidin/ 111 In-biotin scintigraphy was positive in 32/34 patients with spinal infection (94.12% sensitivity). The study was negative in 19/21 patients without infection (95.24% specificity). The corresponding results for MRI and CT were 54.17% and 35.29% (sensitivity), and 75% and 57.14% (specificity), respectively. All statistical parameters of diagnostic performance (Youden's J index, kappa measure of agreement with correct classification, accuracy, sensitivity, specificity, positive likelihood and negative likelihood) were clearly better for streptavidin/ 111 In-biotin scintigraphy than for either MRI or CT. Streptavidin/ 111 In-biotin scintigraphy is highly sensitive and specific for detecting vertebral osteomyelitis in the first 2 weeks after the onset of clinical symptoms, and is potentially very useful for guiding clinical decisions on instituting appropriate therapy. (orig.)

Development of Ferrite-Coated Soft Magnetic Composites: Correlation of Microstructure to Magnetic Properties

Science.gov (United States)

Sunday, Katie Jo

Soft magnetic composites (SMCs) comprised of ferrite-coated ferrous powder permit isotropic magnetic flux capabilities, lower core losses, and complex designs through the use of traditional powder metallurgy techniques. Current coating materials and methods are vastly limited by the nonmagnetic properties of organic and some inorganic coatings and their inability to withstand high heat treatments for proper stress relief of core powder after compaction. Ferrite-based coatings are ferrimagnetic, highly resistive, and boast high melting temperatures, thus providing adequate electrical barriers between metallic particles. These insulating layers are necessary for reducing eddy current losses by increasing resistivity in order to improve the overall magnetic efficiency and subsequent frequency range. The goals of this work are to correlate ferrite-coated Fe powder composites microstructure for the coating and core powder to magnetic properties such as permeability, coercivity, and core loss. We first explore the relevant concepts of SMC materials from their composition to processing steps to pertinent properties. This thesis employs a suite of characterization techniques for powder and composite properties. We use X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to provide a complete understanding of the effect of processing conditions on ferrite-coated Fe-based SMCs. Magnetic, mechanical, and electrical properties are then analyzed to correlate microstructural features and determine their effect on such properties. In the second part of this thesis, we present a proof of concept study on Al2O3- and Al2O3- Fe3O4-coated Fe powder composites, illustrating magnetization is highly dependent on ferromagnetic volume. We then expand on previous work to compare an ideal, crystalline state using Fe3O 4-Fe thin film heterostructures to a highly strained state using bulk powder studies. Fe3O4-coated Fe composites are produced via mechanical

Pharmacokinetics and biodistribution of radiolabeled avidin, streptavidin and biotin

International Nuclear Information System (INIS)

Rosebrough, S.F.

1993-01-01

The extraordinarily high affinity of avidin and streptavidin for biotin may be exploited in a two-step approach for delivering radiolabeled biotin derivatives suitable for imaging and therapy to target-bound streptavidin or avidin conjugated monoclonal antibodies (MAbs). The in vivo pharmacokinetics and biodistribution of radiolabeled avidin, streptavidin (SA) and DTPA-biocytinamide (DTPA-biotin) were studied in the rabbit and dog. SA circulated in the blood similar to other 60 kDa proteins, avidin cleared immediately and DTPA-biotin exhibited plasma clearance by glomerular filtration. (author)

A tosyl-activated magnetic bead cellulose as solid support for sensitive protein detection

Czech Academy of Sciences Publication Activity Database

Yan, J.; Horák, Daniel; Lenfeld, Jiří; Hammond, M.; Kamali-Moghaddam, M.

2013-01-01

Roč. 167, č. 3 (2013), s. 235-240 ISSN 0168-1656 R&D Projects: GA ČR GAP503/10/0664; GA MŠk 7E12054 EU Projects: European Commission(XE) 259796 - DIATOOLS Institutional support: RVO:61389013 Keywords : bead cellulose * magnetic * protein detection Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.884, year: 2013

Planar Hall effect sensor for magnetic micro- and nanobead detection

DEFF Research Database (Denmark)

Ejsing, Louise Wellendorph; Hansen, Mikkel Fougt; Menon, Aric Kumaran

2004-01-01

Magnetic bead sensors based on the planar Hall effect in thin films of exchange-biased permalloy have been fabricated and characterized. Typical sensitivities are 3 muV/Oe mA. The sensor response to an applied magnetic field has been measured without and with coatings of commercially available 2 ...

Mesoporous polymer-coated PAN beads for environmental applications. Fabrication, characterisation and uranium adsorption studies

International Nuclear Information System (INIS)

Aly, Z.; Scales, N.; Davis, J.; Lumpkin, G.

2017-01-01

Adsorption of U(VI) and other heavy metals on millimetre sized polymer-coated polyacrylinitrile (PAN) beads was investigated. PAN was used as scaffolds for the polymer layer thus producing porous material of high surface area, improved mechanical strength and improved adsorption capabilities. Extensive U(VI) adsorption studies were undertaken and results modelled using different kinetic and equilibrium models. Parameters including thermodynamic parameters were evaluated. Sorbent capacities were assessed as 124, 16, and 33 mg g"-"1 for PCP, SPP and Dowex at 60 deg C respectively. U(VI) adsorption mechanism for these adsorbents was postulated. Recovered uranium may be used for production of cheap electricity. (author)

Sensitive detection of nucleic acids by PNA hybridization directed co-localization of fluorescent beads

DEFF Research Database (Denmark)

Shiraishi, Takehiko; Deborggraeve, Stijn; Büscher, Philippe

2011-01-01

)avidin-coated fluorescent beads, differing in size and color [green beads (1 µm) and red beads (5.9 µm)], thereby allowing distinct detection of each PNA probe by conventional fluorescence microscopy. These two PNA beads showed easily detectable co-localization when simultaneously hybridizing to a target nucleic acid...

A solid-phase technique for preparation of no-carrier-added technetium-99m radiopharmaceuticals: application to the streptavidin/biotin system

International Nuclear Information System (INIS)

Dunn-Dufault, Robert; Pollak, Alfred; Fitzgerald, Jane; Thornback, John R.; Ballinger, James R.

2000-01-01

A high effective specific activity (HESA) formulation of a biotin-containing 99m Tc ligand [RP488: dimethyl-Gly-Ser-Cys(Acm)-Lys(Biotin)-Gly] conveniently prepared from solid phase was compared to a typical low effective specific activity (LESA) solution formulation to demonstrate improved targeting to streptavidin in an in vitro assay and in an in vivo rat model. RP488 was coupled to a maleimide-functionalized polyethylene glycol resin via a thiol ether linkage and labeled with 99m Tc-gluconate at room temperature, followed by elution of the HESA 99m Tc-RP488 in saline (minimum specific activity ∼ 1000 TBq/mmol by amino acid analysis). Both HESA and LESA 99m Tc-RP488 labeled at > 90% purity. In vitro, HESA 99m Tc-RP488 incubated with streptavidin-agarose was bound quantitatively, but there was competition from addition of increasing amounts of cold RP488. In rats, radiotracer uptake was evident at the site of implantation of streptavidin-agarose beads for the HESA dose, less uptake of low effective specific activity (LESA) material, and no appreciable uptake in the control rats of the LESA or HESA dose. The target-to-background ratio for HESA 99m Tc-RP488 was 5.4 times that of the control. The solid-phase technology offers a convenient way to prepare high specific activity receptor-targeting 99m Tc radiopharmaceuticals

Ultra-sensitive chemiluminescent detection of Staphylococcus aureus based on competitive binding of Staphylococcus protein A-modified magnetic beads to immunoglobulin G

International Nuclear Information System (INIS)

Xiong, Jie; Wang, Wenwen; Zhou, Yali; Kong, Weijun; Wang, Zhenxing; Fu, Zhifeng

2016-01-01

Staphylococcus protein A (SPA) is a surface protein only expressed naturally in the cell walls of Staphylococcus aureus (S. aureus) and binds specifically to the Fc region of immunoglobulin G (IgG). This fact can be utilized for the detection of S. aureus. Specifically, SPA-modified magnetic beads, compete with S. aureus pathogens for binding to rabbit IgG that previously was labeled with horseradish peroxidase (HRP). The beads were then magnetically separated, and chemiluminescence (CL) was generated by adding the reagents luminol and H_2O_2. Under optimal conditions, the intensity of CL decreases with increasing concentration of S. aureus over a very wide linear range (10 to 1.0 × 10"9 cfu·mL"−"1), with a limit of detection of 6.0 cfu·mL"−"1 at an S/N ratio of 3. The assay (including binding reaction, magnetic separation, washing of beads and detection) is completed within 50 min which is faster than many reported methods. It can well distinguish S. aureus from other Gram-positive and Gram-negative bacteria. The magnetic beads have the beneficial effect of eliminating undesired matrix effects and of concentrating the sample. The method was applied to the analysis of urine, apple juice and glucose injection samples spiked with S. aureus, and recoveries ranged from 85 to 107 %. (author)

Efficient isolation of pure and functional mitochondria from mouse tissues using automated tissue disruption and enrichment with anti-TOM22 magnetic beads.

Directory of Open Access Journals (Sweden)

Andras Franko

Full Text Available To better understand molecular mechanisms regulating changes in metabolism, as observed e.g. in diabetes or neuronal disorders, the function of mitochondria needs to be precisely determined. The usual isolation methods such as differential centrifugation result in isolates of highly variable quality and quantity. To fulfill the need of a reproducible isolation method from solid tissues, which is suitable to handle parallel samples simultaneously, we developed a protocol based on anti-TOM22 (translocase of outer mitochondrial membrane 22 homolog antibody-coupled magnetic beads. To measure oxygen consumption rate in isolated mitochondria from various mouse tissues, a traditional Clark electrode and the high-throughput XF Extracellular Flux Analyzer were used. Furthermore, Western blots, transmission electron microscopic and proteomic studies were performed to analyze the purity and integrity of the mitochondrial preparations. Mitochondrial fractions isolated from liver, brain and skeletal muscle by anti-TOM22 magnetic beads showed oxygen consumption capacities comparable to previously reported values and little contamination with other organelles. The purity and quality of isolated mitochondria using anti-TOM22 magnetic beads was compared to traditional differential centrifugation protocol in liver and the results indicated an obvious advantage of the magnetic beads method compared to the traditional differential centrifugation technique.

Controlled torque on superparamagnetic beads for functional biosensors

NARCIS (Netherlands)

Janssen, X.J.A.; Schellekens, A.J.; van Ommering, K.; IJzendoorn, van L.J.; Prins, M.W.J.

2009-01-01

We demonstrate that a rotating magnetic field can be used to apply a controlled torque on superparamagnetic beads which leads to a tunable bead rotation frequency in fluid. Smooth rotation is obtained for field rotation frequencies many orders of magnitude higher than the bead rotation frequency. A

Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites

Science.gov (United States)

Wu, Shen; Sun, Aizhi; Zhai, Fuqiang; Wang, Jin; Zhang, Qian; Xu, Wenhuan; Logan, Philip; Volinsky, Alex A.

2012-03-01

This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 °C increased the maximum permeability by 72.5%. The result of annealing at 580 °C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites.

Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites

International Nuclear Information System (INIS)

Wu Shen; Sun Aizhi; Zhai Fuqiang; Wang Jin; Zhang Qian; Xu Wenhuan; Logan, Philip; Volinsky, Alex A.

2012-01-01

This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 °C increased the maximum permeability by 72.5%. The result of annealing at 580 °C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites. - Highlights: ► Silicone uniformly coated the powder, increased the operating frequency of SMCs. ► The annealing treatment increased the DC properties of SMCs. ► Annealing at 580 °C increased the maximum permeability by 72.5%. ► Compared with epoxy coated, the SMCs had higher resistivity annealing at 580 °C.

Rapid detection and purification of sequence specific DNA binding proteins using magnetic separation

Directory of Open Access Journals (Sweden)

TIJANA SAVIC

2006-02-01

Full Text Available In this paper, a method for the rapid identification and purification of sequence specific DNA binding proteins based on magnetic separation is presented. This method was applied to confirm the binding of the human recombinant USF1 protein to its putative binding site (E-box within the human SOX3 protomer. It has been shown that biotinylated DNA attached to streptavidin magnetic particles specifically binds the USF1 protein in the presence of competitor DNA. It has also been demonstrated that the protein could be successfully eluted from the beads, in high yield and with restored DNA binding activity. The advantage of these procedures is that they could be applied for the identification and purification of any high-affinity sequence-specific DNA binding protein with only minor modifications.

Multiscale evaluation of cellular adhesion alteration and cytoskeleton remodeling by magnetic bead twisting.

Science.gov (United States)

Isabey, Daniel; Pelle, Gabriel; André Dias, Sofia; Bottier, Mathieu; Nguyen, Ngoc-Minh; Filoche, Marcel; Louis, Bruno

2016-08-01

Cellular adhesion forces depend on local biological conditions meaning that adhesion characterization must be performed while preserving cellular integrity. We presently postulate that magnetic bead twisting provides an appropriate stress, i.e., basically a clamp, for assessment in living cells of both cellular adhesion and mechanical properties of the cytoskeleton. A global dissociation rate obeying a Bell-type model was used to determine the natural dissociation rate ([Formula: see text]) and a reference stress ([Formula: see text]). These adhesion parameters were determined in parallel to the mechanical properties for a variety of biological conditions in which either adhesion or cytoskeleton was selectively weakened or strengthened by changing successively ligand concentration, actin polymerization level (by treating with cytochalasin D), level of exerted stress (by increasing magnetic torque), and cell environment (by using rigid and soft 3D matrices). On the whole, this multiscale evaluation of the cellular and molecular responses to a controlled stress reveals an evolution which is consistent with stochastic multiple bond theories and with literature results obtained with other molecular techniques. Present results confirm the validity of the proposed bead-twisting approach for its capability to probe cellular and molecular responses in a variety of biological conditions.

SABinder: A Web Service for Predicting Streptavidin-Binding Peptides.

Science.gov (United States)

He, Bifang; Kang, Juanjuan; Ru, Beibei; Ding, Hui; Zhou, Peng; Huang, Jian

2016-01-01

Streptavidin is sometimes used as the intended target to screen phage-displayed combinatorial peptide libraries for streptavidin-binding peptides (SBPs). More often in the biopanning system, however, streptavidin is just a commonly used anchoring molecule that can efficiently capture the biotinylated target. In this case, SBPs creeping into the biopanning results are not desired binders but target-unrelated peptides (TUP). Taking them as intended binders may mislead subsequent studies. Therefore, it is important to find if a peptide is likely to be an SBP when streptavidin is either the intended target or just the anchoring molecule. In this paper, we describe an SVM-based ensemble predictor called SABinder. It is the first predictor for SBP. The model was built with the feature of optimized dipeptide composition. It was observed that 89.20% (MCC = 0.78; AUC = 0.93; permutation test, p binders. In either case, it will be helpful and can benefit related scientific community.

Coating possibilities for magnetic switches

International Nuclear Information System (INIS)

Sharp, D.J.; Harjes, H.C.; Mann, G.A.; Morgan, F.A.

1990-01-01

High average power magnetic pulse compression systems are now being considered for use in several applications such as the High Power Radiation Source (HiPoRS) project. Such systems will require high reliability magnetic switches (saturable inductors) that are very efficient and have long lifetimes. One of the weakest components in magnetic switches is their interlaminar insulation. Considerations related to dielectric breakdown, thermal management of compact designs, and economical approaches for achieving these needs must be addressed. Various dielectric insulation and coating materials have been applied to Metglas foil in an attempt to solve the complex technical and practical problems associated with large magnetic switch structures. This work reports various needs, studies, results, and proposals in selecting and evaluating continuous coating approaches for magnetic foil. Techniques such as electrophoretic polymer deposition and surface chemical oxidation are discussed. We also propose continuous photofabrication processes for applying dielectric ribs or spacers to the foil which permit circulation of dielectric liquids for cooling during repetitive operation. 10 refs., 8 figs., 11 tabs

Biotin-Streptavidin Competition Mediates Sensitive Detection of Biomolecules in Enzyme Linked Immunosorbent Assay.

Science.gov (United States)

Lakshmipriya, Thangavel; Gopinath, Subash C B; Tang, Thean-Hock

2016-01-01

Enzyme Linked Immunosorbent Assay (ELISA) is the gold standard assay for detecting and identifying biomolecules using antibodies as the probe. Improving ELISA is crucial for detecting disease-causing agents and facilitating diagnosis at the early stages of disease. Biotinylated antibody and streptavidin-conjugated horse radish peroxide (streptavidin-HRP) often are used with ELISA to enhance the detection of various kinds of targets. In the present study, we used a competition-based strategy in which we pre-mixed free biotin with streptavidin-HRP to generate high-performance system, as free biotin occupies some of the biotin binding sites on streptavidin, thereby providing more chances for streptavidin-HRP to bind with biotinylated antibody. ESAT-6, which is a protein secreted early during tuberculosis infection, was used as the model target. We found that 8 fM of free biotin mixed with streptavidin-HRP anchored the higher detection level of ESAT-6 by four-fold compared with detection without free biotin (only streptavidin-HRP), and the limit of detection of the new method was 250 pM. These results suggest that biotin-streptavidin competition can be used to improve the diagnosis of analytes in other types of sensors.

Monitoring ligand-receptor interactions by photonic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Jeney, Sylvia [M E Mueller Institute for Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, Basel, 4056 (Switzerland); Mor, Flavio; Forro, Laszlo [Laboratory of Complex Matter Physics (LPMC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Koszali, Roland [Institute for Information and Communication Technologies (IICT), University of Applied Sciences of Western Switzerland (HEIG-VD), Rue Galilee 15, CH 1401 Yverdon-les-bains (Switzerland); Moy, Vincent T, E-mail: sylvia.jeney@unibas.ch, E-mail: vmoy@miami.edu [Department of Physiology and Biophysics, University of Miami Miller School of Medicine, 1600 NW 10th Avenue, Miami, FL 33136 (United States)

2010-06-25

We introduce a method for the acquisition of single molecule force measurements of ligand-receptor interactions using the photonic force microscope (PFM). Biotin-functionalized beads, manipulated with an optical trap, and a streptavidin-functionalized coverslip were used to measure the effect of different pulling forces on the lifetime of individual streptavidin-biotin complexes. By optimizing the design of the optical trap and selection of the appropriate bead size, pulling forces in excess of 50 pN were achieved. Based on the amplitude of three-dimensional (3D) thermal position fluctuations of the attached bead, we were able to select for a bead-coverslip interaction that was mediated by a single streptavidin-biotin complex. Moreover, the developed experimental system was greatly accelerated by automation of data acquisition and analysis. In force-dependent kinetic measurements carried out between streptavidin and biotin, we observed that the streptavidin-biotin complex exhibited properties of a catch bond, with the lifetime increasing tenfold when the pulling force increased from 10 to 20 pN. We also show that silica beads were more appropriate than polystyrene beads for the force measurements, as tethers, longer than 200 nm, could be extracted from polystyrene beads.

Monitoring ligand-receptor interactions by photonic force microscopy

International Nuclear Information System (INIS)

Jeney, Sylvia; Mor, Flavio; Forro, Laszlo; Koszali, Roland; Moy, Vincent T

2010-01-01

We introduce a method for the acquisition of single molecule force measurements of ligand-receptor interactions using the photonic force microscope (PFM). Biotin-functionalized beads, manipulated with an optical trap, and a streptavidin-functionalized coverslip were used to measure the effect of different pulling forces on the lifetime of individual streptavidin-biotin complexes. By optimizing the design of the optical trap and selection of the appropriate bead size, pulling forces in excess of 50 pN were achieved. Based on the amplitude of three-dimensional (3D) thermal position fluctuations of the attached bead, we were able to select for a bead-coverslip interaction that was mediated by a single streptavidin-biotin complex. Moreover, the developed experimental system was greatly accelerated by automation of data acquisition and analysis. In force-dependent kinetic measurements carried out between streptavidin and biotin, we observed that the streptavidin-biotin complex exhibited properties of a catch bond, with the lifetime increasing tenfold when the pulling force increased from 10 to 20 pN. We also show that silica beads were more appropriate than polystyrene beads for the force measurements, as tethers, longer than 200 nm, could be extracted from polystyrene beads.

Secretory production of tetrameric native full-length streptavidin with thermostability using Streptomyces lividans as a host.

Science.gov (United States)

Noda, Shuhei; Matsumoto, Takuya; Tanaka, Tsutomu; Kondo, Akihiko

2015-01-13

Streptavidin is a tetrameric protein derived from Streptomyces avidinii, and has tight and specific biotin binding affinity. Applications of the streptavidin-biotin system have been widely studied. Streptavidin is generally produced using protein expression in Escherichia coli. In the present study, the secretory production of streptavidin was carried out using Streptomyces lividans as a host. In this study, we used the gene encoding native full-length streptavidin, whereas the core region is generally used for streptavidin production in E. coli. Tetrameric streptavidin composed of native full-length streptavidin monomers was successfully secreted in the culture supernatant of S. lividans transformants, and had specific biotin binding affinity as strong as streptavidin produced by E. coli. The amount of Sav using S. lividans was about 9 times higher than using E. coli. Surprisingly, streptavidin produced by S. lividans exhibited affinity to biotin after boiling, despite the fact that tetrameric streptavidin is known to lose its biotin binding ability after brief boiling. We successfully produced a large amount of tetrameric streptavidin as a secretory-form protein with unique thermotolerance.

Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells

Science.gov (United States)

Kandel, Prakash K.; Fernando, Lawrence P.; Ackroyd, P. Christine; Christensen, Kenneth A.

2011-03-01

We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing.We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG

Biosensing utilizing the motion of magnetic microparticles in a microfluidic system

KAUST Repository

Giouroudi, Ioanna

2010-10-23

The study for the design of a compact and inexpensive biosensing device, which can be operated either by primary care personnel or by patients as opposed to skilled operators, is presented. The main parts of the proposed device are a microfluidic channel, permanent magnets and functionalized magnetic microparticles. The innovative aspect of the proposed biosensing method is that it utilizes the volumetric increase of magnetic microparticles when analyte binds to their surface. Their velocity decreases drastically when they are accelerated by an externally applied magnetic force within a microfluidic channel. This effect is utilized to detect the presence of analyte e.g. microbes. Analytical calculations showed that a decrease in velocity of approximately 23% can be achieved due to the volumetric change of a magnetic microparticle of View the MathML source1μm diameter when HIV virions of approximately View the MathML source0,135μm are bound to its surface and by keeping its magnetic properties the same. Preliminary experiments were carried out utilizing superparamagnetic microparticles coated with streptavidin and polystyrene microparticles coated with biotin.

Tethered particle analysis of supercoiled circular DNA using peptide nucleic acid handles

DEFF Research Database (Denmark)

Norregaard, Kamilla; Andersson, Magnus; Nielsen, Peter Eigil

2014-01-01

This protocol describes how to monitor individual naturally supercoiled circular DNA plasmids bound via peptide nucleic acid (PNA) handles between a bead and a surface. The protocol was developed for single-molecule investigation of the dynamics of supercoiled DNA, and it allows the investigation...... of both the dynamics of the molecule itself and of its interactions with a regulatory protein. Two bis-PNA clamps designed to bind with extremely high affinity to predetermined homopurine sequence sites in supercoiled DNA are prepared: one conjugated with digoxigenin for attachment to an anti......-digoxigenin-coated glass cover slide, and one conjugated with biotin for attachment to a submicron-sized streptavidin-coated polystyrene bead. Plasmids are constructed, purified and incubated with the PNA handles. The dynamics of the construct is analyzed by tracking the tethered bead using video microscopy: less...

Fabrication of micromagnetic beads with molecular recognition/electron-transfer peptides for the sensing of ovalbumin

Energy Technology Data Exchange (ETDEWEB)

Sugawara, Kazuharu, E-mail: kzsuga@maebashi-it.ac.jp [Maebashi Institute of Technology, Gunma, 371-0816 (Japan); Kuramitz, Hideki [Department of Environmental Biology and Chemistry, Graduate School of Science and Engineering for Research, University of Toyama, Toyama, 930-8555 (Japan); Shinohara, Hiroki [Maebashi Institute of Technology, Gunma, 371-0816 (Japan)

2017-03-15

Electrochemical sensing of ovalbumin (OVA) was performed using magnetic beads with OVA recognition (RNRCKGTDVQAW)/electron-transfer (YYYYC) peptides. The focus of this study was to construct a highly sensitive and regenerative tool for OVA detection based on the interaction between a protein and peptide-1(RNRCKGTDVQAWYYYYC). The peptide-1 was introduced to the bead through four types of cross-linking reagents. Magnetic beads of different sizes with N-(6-maleimidocaproyloxy)sulfosuccinimide (Sulfo-EMCS) were also prepared. An oxidation peak due to tyrosine residues at 0.65 V depended on the distance of the electron-transfer peptide from the bead surface and on the surface area of the magnetic beads that contacted the electrode surface. The response of the electro-transfer peptide moiety was decreased because the protein was accumulated via the recognition peptide on the beads. When using Sulfo-EMCS and beads that were 6.0–6.9 μm in diameter, the calibration curve of OVA was linear and ranged from 8.0 × 10{sup −13} to 2.0 × 10{sup −11} M. To regenerate the magnetic beads, the measurements were achieved after removal of the OVA using a denaturing reagent. When OVA was added to fetal bovine serum containing a complex matrix, OVA was recovered at a rate of 98–100%. Consequently, these magnetic beads could be a powerful tool for the sensing of OVA in real samples. - Highlights: • Ovalbumin recognition/electron-transfer peptides were immobilized on magnetic beads. • The accumulation of the protein through the peptides on the beads caused the change of electrode response. • The magnetic beads could be reused for sensing of ovalbumin.

Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

DEFF Research Database (Denmark)

Kistrup, Kasper; Sørensen, Karen Skotte; Wolff, Anders

2014-01-01

We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible......-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/µg and 1.72(14) nL/µg were found for Milli-Q water and lysis...

Preparation of biodegradable magnetic microspheres with poly(lactic acid)-coated magnetite

Energy Technology Data Exchange (ETDEWEB)

Zhao Hong; Saatchi, Katayoun [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, 6T 1Z3 (Canada); Haefeli, Urs O. [Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, V6T 1Z3 (Canada)], E-mail: uhafeli@interchange.ubc.ca

2009-05-15

Poly(lactic acid) (PLA)-coated magnetic nanoparticles were made using uncapped PLA with free carboxylate groups. The physical properties of these particles were compared to those of oleate-coated or oleate/sulphonate bilayer (W40) coated magnetic particles. Magnetic microspheres (MMS) with the matrix material poly(lactide-co-glycolide) (PLGA) or PLA were then formed by the emulsion solvent extraction method with encapsulation efficiencies of 40%, 83% and 96% for oleate, PLA and oleate/sulfonate-coated magnetic particles, respectively. MMS made from PLA-coated magnetite were hemocompatible and produced no hemolysis, whereas the other MMS were hemolytic above 0.3 mg/mL of blood.

Preparation of biodegradable magnetic microspheres with poly(lactic acid)-coated magnetite

International Nuclear Information System (INIS)

Zhao Hong; Saatchi, Katayoun; Haefeli, Urs O.

2009-01-01

Poly(lactic acid) (PLA)-coated magnetic nanoparticles were made using uncapped PLA with free carboxylate groups. The physical properties of these particles were compared to those of oleate-coated or oleate/sulphonate bilayer (W40) coated magnetic particles. Magnetic microspheres (MMS) with the matrix material poly(lactide-co-glycolide) (PLGA) or PLA were then formed by the emulsion solvent extraction method with encapsulation efficiencies of 40%, 83% and 96% for oleate, PLA and oleate/sulfonate-coated magnetic particles, respectively. MMS made from PLA-coated magnetite were hemocompatible and produced no hemolysis, whereas the other MMS were hemolytic above 0.3 mg/mL of blood.

Effect of algal density in bead, bead size and bead concentrations ...

African Journals Online (AJOL)

Effect of algal density in bead, bead size and bead concentrations on wastewater nutrient removal. ... African Journal of Biotechnology ... The bioreactor containing algal beads (4 mm diameter) with 1.5 x 106 cells bead-1 (cell stocking) at concentration of 10.66 beads ml-1 wastewater (1:3 bead: wastewater, v/v) achieved ...

Magnet polepiece design for uniform magnetic force on superparamagnetic beads

OpenAIRE

Fallesen, Todd; Hill, David B.; Steen, Matthew; Macosko, Jed C.; Bonin, Keith; Holzwarth, George

2010-01-01

Here we report construction of a simple electromagnet with novel polepieces which apply a spatially uniform force to superparamagnetic beads in an optical microscope. The wedge-shaped gap was designed to keep ∂Bx∕∂y constant and B large enough to saturate the bead. We achieved fields of 300–600 mT and constant gradients of 67 T∕m over a sample space of 0.5×4 mm2 in the focal plane of the microscope and 0.05 mm along the microscope optic axis. Within this space the maximum force on a 2.8 μm di...

Effect of endogenous biotin on the applications of streptavidin and biotin in mice

International Nuclear Information System (INIS)

Rusckowski, Mary; Fogarasi, Miklos; Fritz, Benjamin; Hnatowich, Donald J.

1997-01-01

The use of streptavidin-conjugated antibody to pretarget tumors in animals and patients, prior to administration of radiolabeled biotin, has provided encouraging results, in part because of the high affinity of biotin for streptavidin and the rapid whole-body clearance of biotin. However, binding of endogenous biotin to streptavidin may interfere with the clinical potential of this approach. This report evaluates the effect of endogenous biotin on an antibody-streptavidin conjugate in a mouse tumor model. Tumored nude mice were depleted of endogenous biotin by sequential intraperitoneal injections of streptavidin. The assay of serum biotin levels indicated less than 0.5 ng of biotin per mL of serum in treated mice versus 4 ng per mL in untreated animals. Flow cytometric analysis was used on single-cell suspensions of tumor from animals receiving streptavidin-conjugated IgG to detect the presence of the antibody on the cell membrane (with fluoroisothiocyanate-conjugated goat anti-mouse antibody), and to detect biotin binding sites on streptavidin (with biotin-phycoerythrin). Both treated and untreated mice demonstrated the presence of antibody on tumor cells through 48 h postadministration, but only in treated animals were biotin binding sites observed. These results in the mouse model suggest that the small concentration of streptavidin delivered to a tumor via a specific antibody may be saturated with endogenous biotin and therefore not able to be targeted subsequently with radiolabeled biotin

Streptavidin-binding peptides and uses thereof

Science.gov (United States)

Szostak, Jack W. (Inventor); Wilson, David S. (Inventor); Keefe, Anthony D. (Inventor)

2006-01-01

The invention provides peptides with high affinity for streptavidin. These peptides may be expressed as part of fusion proteins to facilitate the detection, quantitation, and purification of proteins of interest.

Magnetic properties of permalloy-coated organic tubules

Science.gov (United States)

Krebs, J. J.; Rubinstein, M.; Lubitz, P.; Harford, M. Z.; Baral, S.; Shashidar, R.; Ho, Y. S.; Chow, G. M.; Qadri, S.

1991-11-01

An initial investigation is presented of the ferromagnetic properties of a novel type of magnetic composite, viz., permalloy-coated submicron diameter hollow cylinders or tubules. The tubules form spontaneously from an organic material, a diacetylenic phosopholipid, and were used as templates on which the ferromagnetic material was deposited by electroless deposition. The permalloy-coated tubules were dispersed in an epoxy matrix to measure the magnetization and ferromagnetic resonance (FMR) properties of individual tubules. The nature of the magnetic anisotropy and the FMR spectra observed confirmed that the tubules are well aligned by a magnetic field during the epoxy curing. The FMR spectra are interpreted in terms of a powder pattern distribution of thin-film spectra consistent with the large diameter-to-thickness ratio.

Artificial Metalloenzymes Based on the Biotin-Streptavidin Technology: Challenges and Opportunities.

Science.gov (United States)

Heinisch, Tillmann; Ward, Thomas R

2016-09-20

The biotin-streptavidin technology offers an attractive means to engineer artificial metalloenzymes (ArMs). Initiated over 50 years ago by Bayer and Wilchek, the biotin-(strept)avidin techonology relies on the exquisite supramolecular affinity of either avidin or streptavidin for biotin. This versatile tool, commonly referred to as "molecular velcro", allows nearly irreversible anchoring of biotinylated probes within a (strept)avidin host protein. Building upon a visionary publication by Whitesides from 1978, several groups have been exploiting this technology to create artificial metalloenzymes. For this purpose, a biotinylated organometallic catalyst is introduced within (strept)avidin to afford a hybrid catalyst that combines features reminiscent of both enzymes and organometallic catalysts. Importantly, ArMs can be optimized by chemogenetic means. Combining a small collection of biotinylated organometallic catalysts with streptavidin mutants allows generation of significant diversity, thus allowing optimization of the catalytic performance of ArMs. Pursuing this strategy, the following reactions have been implemented: hydrogenation, alcohol oxidation, sulfoxidation, dihydroxylation, allylic alkylation, transfer hydrogenation, Suzuki cross-coupling, C-H activation, and metathesis. In this Account, we summarize our efforts in the latter four reactions. X-ray analysis of various ArMs based on the biotin-streptavidin technology reveals the versatility and commensurability of the biotin-binding vestibule to accommodate and interact with transition states of the scrutinized organometallic transformations. In particular, streptavidin residues at positions 112 and 121 recurrently lie in close proximity to the biotinylated metal cofactor. This observation led us to develop a streamlined 24-well plate streptavidin production and screening platform to optimize the performance of ArMs. To date, most of the efforts in the field of ArMs have focused on the use of purified

Enhanced protein adsorption and patterning on nanostructured latex-coated paper.

Science.gov (United States)

Juvonen, Helka; Määttänen, Anni; Ihalainen, Petri; Viitala, Tapani; Sarfraz, Jawad; Peltonen, Jouko

2014-06-01

Specific interactions of extracellular matrix proteins with cells and their adhesion to the substrate are important for cell growth. A nanopatterned latex-coated paper substrate previously shown to be an excellent substrate for cell adhesion and 2D growth was studied for directed immobilization of proteins. The nanostructured latex surface was formed by short-wavelength IR irradiation of a two-component latex coating consisting of a hydrophilic film-forming styrene butadiene acrylonitrile copolymer and hydrophobic polystyrene particles. The hydrophobic regions of the IR-treated latex coating showed strong adhesion of bovine serum albumin (cell repelling protein), fibronectin (cell adhesive protein) and streptavidin. Opposite to the IR-treated surface, fibronectin and streptavidin had a poor affinity toward the untreated pristine latex coating. Detailed characterization of the physicochemical surface properties of the latex-coated substrates revealed that the observed differences in protein affinity were mainly due to the presence or absence of the protein repelling polar and charged surface groups. The protein adsorption was assisted by hydrophobic (dehydration) interactions. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanohole 3D-size tailoring through polystyrene bead combustion during thin film deposition

International Nuclear Information System (INIS)

Peng Xiaofeng; Kamiya, Itaru

2009-01-01

A novel approach is presented for nanohole 3D-size tailoring. The process starts with a monolayer of polystyrene (PS) beads spun coat on silicon wafer as a template. The holes can be directly prepared through combustion of PS beads by oxygen plasma during metal or oxide thin film deposition. The incoming particles are prevented from adhering on PS beads by H 2 O and CO 2 generated from the combustion of the PS beads. The hole depth generally depends on the film thickness. The hole diameter can be tailored by the PS bead size, film deposition rate, and also the combustion speed of the PS beads. In this work, a series of holes with depth of 4-24 nm and diameter of 10-36 nm has been successfully prepared. The hole wall materials can be selected from metals such as Au or Pt and oxides such as SiO 2 or Al 2 O 3 . These templates could be suitable for the preparation and characterization of novel nanodevices based on single quantum dots or single molecules, and could be extended to the studies of a wide range of coating materials and substrates with controlled hole depth and diameters.

PVD Ti coatings on Sm-Co magnets

International Nuclear Information System (INIS)

Bovda, O.M.; Bovda, V.O.; Garkusha, I.E.; Leonov, S.O.; Onishchenko, L.V.; Tereshin, V.I.; Totrika, O.S.; Chen, C.H.

2008-01-01

The combination of conventional ion-plasma deposition (PVD) and pulsed plasma technologies (PPT) has been applied for rare-earth Sm-Co based magnets, to provide them with enhanced corrosion resistance. The influence of pulsed plasma treatment on Sm-Co magnets with deposited titanium PVD coatings has been investigated. It was revealed that thickness of modified layer significantly depends on the thickness of initial titanium film and plasma treatment regimes. As a result of plasma treatment with energy density of 30 J/cm 2 and pulse duration of ∼ 5 μs fine-grained layer with the thickness of 70 microns has been formed on the Sm-Co magnet with pure titanium film of 50 micron. According to SEM analyses considerable diffusion of titanium to the bulk of the magnet, on the depth of 20 microns, took place. Such reaction enhances strong bonding between the coating and the magnet

Fabrication of magnetic alginate beads with uniform dispersion of CoFe2O4 by the polydopamine surface functionalization for organic pollutants removal

Science.gov (United States)

Li, Xiaoli; Lu, Haijun; Zhang, Yun; He, Fu; Jing, Lingyun; He, Xinghua

2016-12-01

A simple and efficient method for production of magnetic composites by decorating CoFe2O4 with polydopamine (PDA) through oxidative polymerization of dopamine was conducted. Further, magnetic alginate beads with porous structure containing well-dispersed CoFe2O4-PDA were fabricated by ionic crosslinking technology. The resulting SA@CoFe2O4-PDA beads were characterized using scanning electron microscopy, Fourier transform infrared spectrometry, X-ray diffractometer, vibrating sample magnetometer and X-ray photoelectron spectroscopy. Adsorption potential of SA@CoFe2O4-PDA beads for organic dyes including Methylene Blue (MB), Crystal Violet (CV) and Malachite Green (MG) was evaluated. SA@CoFe2O4-PDA beads exhibited excellent adsorption performances due to the composite effect, large surface area and porous structure. Organic dyes could be removed from water solution with high efficiency in a wide pH range of 4.0-9.0. Moreover, it exhibited much higher adsorptivity towards MB and CV with the maximum adsorption capacities of 466.60 and 456.52 mg/g, respectively, which were much higher than that of MG (248.78 mg/g). Ca-electrolyte had obvious adverse effects on MB and CV adsorption than MG. FTIR and XPS demonstrated that carboxylate, catechol, hydroxyl and amine groups might be involved in adsorption of organic dyes. The characteristics of wide pH range, high adsorption capacity and convenient magnetic separation would make SA@CoFe2O4-PDA beads as effective adsorbent for removal of organic dyes from wastewater.

Separation of magnetic beads in a hybrid continuous flow microfluidic device

Energy Technology Data Exchange (ETDEWEB)

Samanta, Abhishek [Haldia Institute of Technology, Production Engineering Department, Haldia (India); Ganguly, Ranjan; Datta, Amitava [Jadavpur University, Power Engineering Department (India); Modak, Nipu, E-mail: nmechju@gmail.com [Jadavpur University, Mechanical Engineering Department (India)

2017-04-01

Magnetic separation of biological entities in microfluidic environment is a key task for a large number of bio-analytical protocols. In magnetophoretic separation, biochemically functionalized magnetic beads are allowed to bind selectively to target analytes, which are then separated from the background stream using a suitably imposed magnetic field. Here we present a numerical study, characterizing the performance of a magnetophoretic hybrid microfluidic device having two inlets and three outlets for immunomagnetic isolation of three different species from a continuous flow. The hybrid device works on the principle of split-flow thin (SPLITT) fractionation and field flow fractionation (FFF) mechanisms. Transport of the magnetic particles in the microchannel has been predicted following an Eulerian-Lagrangian model and using an in-house numerical code. Influence of the salient geometrical parameters on the performance of the separator is studied by characterizing the particle trajectories and their capture and separation indices. Finally, optimum channel geometry is identified that yields the maximum capture efficiency and separation index. - Highlights: • Immunomagnetic separation in a hybrid microchannel design is investigated numerically. • Influence of salient geometric parameters on the device performance is analysed. • Optimum device dimension for best separation parameters are identified. • Optimized design of hybrid separator performs better than FFF or SPLITT devices.

Silica-supported Macroporous Chitosan Bead for Affinity Purification of Trypsin Inhibitor

Institute of Scientific and Technical Information of China (English)

Feng Na XI; Jian Min WU; Ming Ming LUAN

2005-01-01

Macroporous cross-linking chitosan layer coated on silica gel (CTS-SiO2) was prepared by phase inversion and polyethylene glycol (PEG) molecular imprinting methods. Formation of macroporous surface was investigated by scanning electron microscopy (SEM) and BET analysis.The prepared bead was activated by reacting with 1,2-ethylene diglycidyl ether for introducing epoxy groups, and trypsin could be efficiently immobilized on the bead as a biospecific ligand.The bead bearing trypsin was employed to purify trypsin inhibitor (TIs) from egg white as affinity adsorbent.

Plasma spraying of hard magnetic coatings based on Sm-Co alloys

International Nuclear Information System (INIS)

KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Saunin, V N; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Telegin, S V

2015-01-01

Our research is focused on the formation of hard magnetic coatings by plasma spraying an arc-melted Sm-Co powder. We have studied basic magnetic characteristics depending on the components ratio in the alloy. A sample with a 40 wt.% Sm coating exhibits the highest coercive force (63 kOe) as compared to near-to-zero coercive force in the starting powder. X-ray structure analysis of the starting alloy and the coating reveals that the amount of SmCo 5 phase in the sprayed coating increases occupying up to 2/3 of the sample. We have also studied temperature dependence of the coating and have been able to obtain plasma sprayed permanent magnets operating within the temperature range from -100 to +500 °C. The technique used does not involve any additional thermal treatment and allows a coating to be formed right on the magnetic conductor surface irrespective of the conductor geometry

Improved tumor localization with (strept)avidin and labeled biotin as a substitute for antibody

International Nuclear Information System (INIS)

Hnatowich, D.J.; Fritz, B.; Virzi, F.; Mardirossian, G.; Rusckowski, M.

1993-01-01

We have investigated tumor localization with labeled biotin administered subsequent to unlabeled and unconjugated streptavidin. Nude mice bearing anti-CEA tumors (LS174T) received 10 μg of 111 In-labeled anti-CEA antibody (C110) or 111 In-labeled streptavidin with sacrifice 5 h later. In an examination of pretargeting, other animals received 50 μg of unlabeled streptavidin followed 3 h later with 1 μg of 111 In-labeled biotin (EB 1 ) and sacrifice 2 h later. The biodistribution of labeled streptavidin was similar to that of labeled specific antibody except for lower blood and higher kidney levels. Tumor levels were also lower with labeled streptavidin but, because of still lower levels in liver and blood, the tumor/normal tissue ratios were improved. When unlabeled streptavidin was administered and followed by labeled biotin (pretargeting), tumor levels were further reduced modestly; however, normal tissue levels were greatly reduced such that the tumor/blood and tumor/liver ratios were 10.6 and 2.2 vs 1.5 and 0.5 for the specific antibody. Improvements were seen in all tissues sampled with the exception of kidney and muscle. A further control of labeled biotin alone (without the preinjection of streptavidin) showed minimal accumulations in all tissues with the exception of kidneys. In conclusion, the accumulation of (strept)avidin by passive diffusion in tumor may be comparable, at early times, to the accumulation of specific antibody. (author)

Immobilization of streptavidin on 4H-SiC for biosensor development

International Nuclear Information System (INIS)

Williams, Elissa H.; Davydov, Albert V.; Motayed, Abhishek; Sundaresan, Siddarth G.; Bocchini, Peter; Richter, Lee J.; Stan, Gheorghe; Steffens, Kristen; Zangmeister, Rebecca; Schreifels, John A.; Rao, Mulpuri V.

2012-01-01

A sequential layer formation chemistry is demonstrated for the functionalization of silicon carbide (SiC) appropriate to biosensing applications. (0 0 0 1) 4H-SiC was functionalized with 3-aminopropyltriethoxysilane (APTES) and subsequently biotinylated for the selective immobilization of streptavidin. Atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, fluorescence microscopy, and contact angle measurements were utilized to determine the structure, thickness, wettability, and reactivity of the resulting surface after each functionalization step. Optimization of the APTES layer was found to be critical to the success of the subsequent steps; multilayer, polymeric films resulted in irreproducible behavior. It was shown that there was significant non-specific (electrostatic) binding of streptavidin to APTES functionalized SiC, thus revealing the importance of a uniform biotinylation step prior to streptavidin attachment. The experimental results demonstrate that the APTES functionalized and biotinylated SiC surface has the potential to be employed as a biosensing platform for the selective detection of streptavidin molecules.

Intravenous avidin chase improved localization of radiolabeled streptavidin in intraperitoneal xenograft pretargeted with biotinylated antibody

International Nuclear Information System (INIS)

Zhang Meili; Sakahara, Harumi; Yao Zhengsheng; Saga, Tsuneo; Nakamoto, Yuhi; Sato, Noriko; Nakada, Hiroshi; Yamashina, Ikuo; Konishi, Junji

1997-01-01

In the present study, we examined the effect of avidin administered intravenously (i.v.) on the biodistribution of radiolabeled streptavidin in mice bearing intraperitoneal (IP) xenografts pretargeted with biotinylated antibody. Tumors were established in nude mice by IP inoculation of LS180 human colon cancer cells. Monoclonal antibody MLS128, which recognizes Tn antigen on mucin, was biotinylated and injected IP into the IP tumor-bearing mice. Radioiodinated streptavidin was administered IP or i.v. 48 h after pretargeting of biotinylated antibody. Avidin was administered i.v. 30 min prior to streptavidin injection. The localization of radioiodinated streptavidin in the tumor pretargeted with biotinylated antibody was significantly higher than that without pretargeting and that of radioiodinated MLS128 by the one-step method. Avidin administration significantly accelerated the clearance of radioiodinated streptavidin in blood and other normal tissues and increased the tumor-to-blood radioactivity ratio regardless of administration route of streptavidin. The i.v. avidin chase improved tumor localization of radiolabeled streptavidin in the IP xenografts pretargeted with biotinylated antibody

The Motion of a Single Molecule, the Lambda-Receptor, in the Bacterial Outer Membrane

DEFF Research Database (Denmark)

Oddershede, Lene; Dreyer, Jakob Kisbye; Grego, Sonia

2002-01-01

Using optical tweezers and single particle tracking, we have revealed the motion of a single protein, the lambda-receptor, in the outer membrane of living Escherichia coli bacteria. We genetically modified the lambda-receptor placing a biotin on an extracellular site of the receptor in vivo....... The efficiency of this in vivo biotinylation is very low, thus enabling the attachment of a streptavidin-coated bead binding specifically to a single biotinylated lambda-receptor. The bead was used as a handle for the optical tweezers and as a marker for the single particle tracking routine. We propose a model...

Ferrite bead effect on Class-D amplifier audio quality

OpenAIRE

Haddad , Kevin El; Mrad , Roberto; Morel , Florent; Pillonnet , Gael; Vollaire , Christian; Nagari , Angelo

2014-01-01

International audience; This paper studies the effect of ferrite beads on the audio quality of Class-D audio amplifiers. This latter is a switch-ing circuit which creates high frequency harmonics. Generally, a filter is used at the amplifier output for the sake of electro-magnetic compatibility (EMC). So often, in integrated solutions, this filter contains ferrite beads which are magnetic components and present nonlinear behavior. Time domain measurements and their equivalence in frequency do...

Floating-bioadhesive gastroretentive Caesalpinia pulcherrima-based beads of amoxicillin trihydrate for Helicobacter pylori eradication.

Science.gov (United States)

Thombre, Nilima A; Gide, Paraag S

2016-01-01

An oral dosage form containing floating bioadhesive gastroretentive microspheres forms a stomach-specific drug delivery system for the treatment of Helicobacter pylori. To prepare and evaluate controlled release floating bioadhesive gastroretentive chitosan-coated amoxicillin trihydrate-loaded Caesalpinia pulcherrima galactomannan (CPG)-alginate beads (CCA-CPG-A), for H. pylori eradication. CCA-CPG-A beads were prepared by ionotropic gelation, using 2(3) factorial design with quantity of drug, combination of CPG with sodium alginate and concentration of calcium chloride as variables. Beads facilitated mucoadhesion to gastric mucosa with floating nature caused by chitosan coating for wide distribution throughout GIT. Developed beads were evaluated for characteristics like beads size-morphology, entrapment efficiency, DSC, XRD, FTIR, swelling ratio, in vitro mucoadhesion, in vitro drug release, in vitro floating and in vitro H. pylori growth inhibition studies. CCA-CPG-A beads were studied in Wistar rats for in vivo gastric mucoadhesion, in vivo H. pylori growth inhibition studies using PCR amplification of isolated DNA, rapid urease test. Developed beads possess drug release of 79-92%, entrapment efficiency of 65-89%, mucoadhesion of 61-89%. In vivo mucoadhesion study showed more than 85% mucoadhesion of beads even after 7th hour. In vitro-in vivo growth inhibition study showed complete eradication of H. pylori. CPG-alginate and chitosan in beads interacts with gastric mucosubstrate surface for prolonged gastric residence with floating bioadhesion mechanism for H. pylori eradication in rats. Floating bioadhesive CCA-CPG-A beads offer a promising drug delivery system for H. pylori eradication at lower dose, reduced adverse effect and enhance bioavailability.

Improved tumor localization with (strept)avidin and labeled biotin as a substitute for antibody

International Nuclear Information System (INIS)

Hnatowich, D.J.; Fritz, B.; Virzi, F.; Mardirossian, G.; Rusckowski, M.

1993-01-01

We have investigated tumor localization with labeled biotin administered subsequent to unlabeled and unconjugated streptavidin. Nude mice bearing anti-CEA tumors (LS174T) received 10 μg of 111 In-labeled anti-CEA antibody (C110) or 111 In-labeled streptavidin with sacrifice 5 h later. In an examination of pretargeting, other animals received 50 μg of unlabeled streptavidin followed 3 h later with 1 μg of 111 In-labeled biotin (EB 1 ) and sacrifice 2 h later. The biodistribution of labeled streptavidin was similar to that of labeled specific antibody except for lower blood and higher kidney levels. Tumor levels were also lower with labeled streptavidin but, because of still lower levels in liver and blood, the tumor/normal tissue ratios were improved. When unlabeled streptavidin was administered and followed by labeled biotin (pretargeting), tumor levels were further reduced modestly; however, normal tissue levels were greatly reduced such that the tumor/blood and tumor/liver ratios were 10.6 and 2.2 vs 1.5 and 0.5 for the specific antibody. Improvements were seen in all tissues sampled with the exception of kidney and muscle. A further control of labeled biotin alone showed minimal accumulation in all tissues with the exception of kidneys. In conclusion, the accumulation of (strept)avidin by passive diffusion in tumor may be comparable, at early times, to the accumulation of specific antibody. By combining the administration of unlabeled (strept)avidin with labeled biotin, tumor targeting may potentially be improved. (author)

Magnetic bead/capture DNA/glucose-loaded nanoliposomes for amplifying the glucometer signal in the rapid screening of hepatitis C virus RNA.

Science.gov (United States)

Tu, Haijian; Lin, Kun; Lun, Yongzhi; Yu, Liuming

2018-06-01

A digital detection strategy based on a portable personal glucometer (PGM) was developed for the simple, rapid, and sensitive detection of hepatitis C virus (HCV) RNA, involving the release of glucose-loaded nanoliposomes due to coupling-site-specific cleavage by the endonuclease BamHI. The glucose-loaded nanoliposomes were synthesized using a reversed-phase evaporation method and provided an amplified signal at the PGM in the presence of HCV RNA. Initially, a 21-mer oligonucleotide complementary to HCV RNA was covalently conjugated to a magnetic bead through the amino group at the 5' end of the oligonucleotide, and then bound to a glucose-loaded liposome by typical carbodiimide coupling at its 3' end. In the presence of the target HCV RNA, the target hybridized with the oligonucleotide to form double-stranded DNA. The symmetrical duplex sequence 5'-GGATCC-3' between guanines was then catalytically cleaved by BamHI, which detached the glucose-loaded liposome from the magnetic bead. Following magnetic separation of the bead, the detached glucose-loaded liposome was lysed using Triton X-100 to release the glucose molecules within it, which were then detected as an amplified signal at the digital PGM. Under optimal conditions, the PGM signal increased with increasing HCV RNA, and displayed a strongly linear dependence on the level of HCV RNA for concentrations ranging from 10 pM to 1.0 μM. The detection limit (LOD) of the system was 1.9 pM. Good reproducibility and favorable specificity were achieved in the analysis of the target HCV RNA. Human serum samples containing HCV RNA were analyzed using this strategy, and the developed sensing platform was observed to yield satisfactory results based on a comparison with the corresponding results from a Cobas ® Amplicor HCV Test Analyzer. Graphical abstract A digital detection strategy utilizing a personal glucometer was developed for the detection of hepatitis C virus RNA. The strategy involved the use of the

On-Chip Magnetic Bead Manipulation and Detection Using a Magnetoresistive Sensor-Based Micro-Chip: Design Considerations and Experimental Characterization

KAUST Repository

Gooneratne, Chinthaka Pasan; Kodzius, Rimantas; Li, Fuquan; Foulds, Ian G.; Kosel, Jü rgen

2016-01-01

The remarkable advantages micro-chip platforms offer over cumbersome, time-consuming equipment currently in use for bio-analysis are well documented. In this research, a micro-chip that includes a unique magnetic actuator (MA) for the manipulation of superparamagnetic beads (SPBs), and a magnetoresistive sensor for the detection of SPBs is presented. A design methodology, which takes into account the magnetic volume of SPBs, diffusion and heat transfer phenomena, is presented with the aid of numerical analysis to optimize the parameters of the MA. The MA was employed as a magnetic flux generator and experimental analysis with commercially available COMPEL™ and Dynabeads® demonstrated the ability of the MA to precisely transport a small number of SPBs over long distances and concentrate SPBs to a sensing site for detection. Moreover, the velocities of COMPEL™ and Dynabead® SPBs were correlated to their magnetic volumes and were in good agreement with numerical model predictions. We found that 2.8 μm Dynabeads® travel faster, and can be attracted to a magnetic source from a longer distance, than 6.2 μm COMPEL™ beads at magnetic flux magnitudes of less than 10 mT. The micro-chip system could easily be integrated with electronic circuitry and microfluidic functions, paving the way for an on-chip biomolecule quantification device

On-Chip Magnetic Bead Manipulation and Detection Using a Magnetoresistive Sensor-Based Micro-Chip: Design Considerations and Experimental Characterization

KAUST Repository

Gooneratne, Chinthaka Pasan

2016-08-26

The remarkable advantages micro-chip platforms offer over cumbersome, time-consuming equipment currently in use for bio-analysis are well documented. In this research, a micro-chip that includes a unique magnetic actuator (MA) for the manipulation of superparamagnetic beads (SPBs), and a magnetoresistive sensor for the detection of SPBs is presented. A design methodology, which takes into account the magnetic volume of SPBs, diffusion and heat transfer phenomena, is presented with the aid of numerical analysis to optimize the parameters of the MA. The MA was employed as a magnetic flux generator and experimental analysis with commercially available COMPEL™ and Dynabeads® demonstrated the ability of the MA to precisely transport a small number of SPBs over long distances and concentrate SPBs to a sensing site for detection. Moreover, the velocities of COMPEL™ and Dynabead® SPBs were correlated to their magnetic volumes and were in good agreement with numerical model predictions. We found that 2.8 μm Dynabeads® travel faster, and can be attracted to a magnetic source from a longer distance, than 6.2 μm COMPEL™ beads at magnetic flux magnitudes of less than 10 mT. The micro-chip system could easily be integrated with electronic circuitry and microfluidic functions, paving the way for an on-chip biomolecule quantification device

On-Chip Magnetic Bead Manipulation and Detection Using a Magnetoresistive Sensor-Based Micro-Chip: Design Considerations and Experimental Characterization

Directory of Open Access Journals (Sweden)

Chinthaka P. Gooneratne

2016-08-01

Full Text Available The remarkable advantages micro-chip platforms offer over cumbersome, time-consuming equipment currently in use for bio-analysis are well documented. In this research, a micro-chip that includes a unique magnetic actuator (MA for the manipulation of superparamagnetic beads (SPBs, and a magnetoresistive sensor for the detection of SPBs is presented. A design methodology, which takes into account the magnetic volume of SPBs, diffusion and heat transfer phenomena, is presented with the aid of numerical analysis to optimize the parameters of the MA. The MA was employed as a magnetic flux generator and experimental analysis with commercially available COMPEL™ and Dynabeads® demonstrated the ability of the MA to precisely transport a small number of SPBs over long distances and concentrate SPBs to a sensing site for detection. Moreover, the velocities of COMPEL™ and Dynabead® SPBs were correlated to their magnetic volumes and were in good agreement with numerical model predictions. We found that 2.8 μm Dynabeads® travel faster, and can be attracted to a magnetic source from a longer distance, than 6.2 μm COMPEL™ beads at magnetic flux magnitudes of less than 10 mT. The micro-chip system could easily be integrated with electronic circuitry and microfluidic functions, paving the way for an on-chip biomolecule quantification device.

Effect of algal density in bead, bead size and bead concentrations ...

African Journals Online (AJOL)

Laboratory experiments were performed to study nitrogen and phosphorus uptake by the unicellular green microalga Chlorella vulgaris immobilized in calcium alginate beads. Different cell stockings in beads, different bead sizes and different algal bead concentrations in wastewaters were tested. Significant higher nutrients ...

Novel highly porous magnetic hydrogel beads composed of chitosan and sodium citrate: an effective adsorbent for the removal of heavy metals from aqueous solutions.

Science.gov (United States)

Pu, Shengyan; Ma, Hui; Zinchenko, Anatoly; Chu, Wei

2017-07-01

This research focuses on the removal of heavy metal ions from aqueous solutions using magnetic chitosan hydrogel beads as a potential sorbent. Highly porous magnetic chitosan hydrogel (PMCH) beads were prepared by a combination of in situ co-precipitation and sodium citrate cross-linking. Fourier transform infrared spectroscopy indicated that the high sorption efficiency of metal cations is attributable to the hydroxyl, amino, and carboxyl groups in PMCH beads. Thermogravimetric analysis demonstrated that introducing Fe 3 O 4 nanoparticles increases the thermal stability of the adsorbent. Laser confocal microscopy revealed highly uniform porous structure of the resultant PMCH beads, which contained a high moisture content (93%). Transmission electron microscopy micrographs showed that the Fe 3 O 4 nanoparticles, with a mean diameter of 5 ± 2 nm, were well dispersed inside the chitosan beads. Batch adsorption experiments and adsorption kinetic analysis revealed that the adsorption process obeys a pseudo-second-order model. Isotherm data were satisfactorily described by the Langmuir equation, and the maximum adsorption capacity of the adsorbent was 84.02 mg/g. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectra analyses were performed to confirm the adsorption of Pb 2+ and to identify the adsorption mechanism.

The Role of an Aggrecan 32mer Fragment in Post-Traumatic Osteoarthritis

Science.gov (United States)

2017-10-01

streptavidin-coated AlphaLISA donor beads and incubate for 30 minutes.  Read sample absorbance at 615nm on the PerkinElmer Enspire plate reader. 11...HRPO approval within the next six months. Nothing to report 15 Significant changes in use or care of human subjects, vertebrate animals ...human subjects, vertebrate animals , biohazards, and/or select agents during the reporting period. If required, were these changes approved by the

Magnetic Bead and Fluorescent Silica Nanoparticles Based Optical Immunodetection of Staphylococcal Enterotoxin B (SEB in Bottled Water

Directory of Open Access Journals (Sweden)

Shiva K. RASTOGI

2009-10-01

Full Text Available Staphylococcal enterotoxins (SEs are a major cause of food-borne diseases, most commonly SEs assayed immunologically with ELISA. An immunoassay based on fluorescein dye doped silica dioxide nanoparticles (F-SiNPs and magnetic bead (MB is described here for the detection of staphylococcal enterotoxin B (SEB. F-SiNPs have unique optical properties which make them attractive for biosensing. The water-in-oil (W/O reverse microemulsion method was used for the synthesis of F-SiNPs (~ 95 nm of diameter. The F-SiNPs were characterized using SEM, TEM and FTIR spectroscopy. The detection of SEB is preformed in PBS buffer, and bottled drinking water using sandwich immunoassay format. Target analytes were captured using MBs modified with the antigen-specific “capture” antibody, and detected using F-SiNP labeled secondary antigen-specific antibody. We report a limit of detection down to 1 ng/mL SEB spiked sample in less than 2 hr assay time using fluorocount method. This study demonstrates the bio warfare agent SEB capture by magnetic beads and detection using F-SiNPs.

Novel biosensor system model based on fluorescence quenching by a fluorescent streptavidin and carbazole-labeled biotin.

Science.gov (United States)

Zhu, Xianwei; Shinohara, Hiroaki; Miyatake, Ryuta; Hohsaka, Takahiro

2016-10-01

In the present study, a novel molecular biosensor system model was designed by using a couple of the fluorescent unnatural mutant streptavidin and the carbazole-labeled biotin. BODIPY-FL-aminophenylalanine (BFLAF), a fluorescent unnatural amino acid was position-specifically incorporated into Trp120 position of streptavidin by four-base codon method. On the other hand, carbazole-labeled biotin was synthesized as a quencher for the fluorescent Trp120BFLAF mutant streptavidin. The fluorescence of fluorescent Trp120BFLAF mutant streptavidin was decreased as we expected when carbazole-labeled biotin was added into the mutant streptavidin solution. Furthermore, the fluorescence decrease of Trp120BFLAF mutant streptavidin with carbazole-labeled biotin (100 nM) was recovered by the competitive addition of natural biotin. This result demonstrated that by measuring the fluorescence quenching and recovery, a couple of the fluorescent Trp120BFLAF mutant streptavidin and the carbazole-labeled biotin were successfully applicable for quantification of free biotin as a molecular biosensor system. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Sampling polyhexamethylene guanidine aerosols using eosin Y-coated glass beads

International Nuclear Information System (INIS)

Choi, Sang Hyun; Park, Seon Kyung; Kang, Hyun Joong; Kwon, Jung Hwan; Lee, Kyu Hong

2015-01-01

Fatalities caused by the use of polyhexamethylene guanidine (PHMG), a general-purpose chemical germicide used as a humidifier disinfectant in Korea, have raised concerns about exposure to biocide aerosols in indoor environments. A sampler capable of accumulating PHMG from aqueous aerosols was developed as an alternative to low-volume air samplers. This sampler was prepared by placing glass beads coated with 2-(2,4,5,7-tetrabromo-6-oxido-3-oxo-3H-xanthen-9-yl)benzoate (Eosin Y) in a custom-made plastic holder. Passive sampling rates, measured in a bench-top exposure chamber at two different aqueous PHMG aerosol generation rates, were found to be independent of the experimental conditions. This suggests that the capacity of the sampler to accumulate the PHMG aerosol was sufficient for the sampling duration tested. However, the passive sampling rate was 7.6 × 10"−"6 m"3/h for the sampler area of 22 cm"2. This rate is lower than the typical human breathing rate and inadequate for quantitative instrumental analyses at low concentrations in indoor air. A 30-fold enhancement of the sampling rate was achieved by forced convection using a commercial battery-operated fan at ≥2000 rpm. With this accelerated sampling rate, the sampler could be used to monitor time-integrated concentrations of PHMG aerosols in the air

Sampling polyhexamethylene guanidine aerosols using eosin Y-coated glass beads

Energy Technology Data Exchange (ETDEWEB)

Choi, Sang Hyun; Park, Seon Kyung; Kang, Hyun Joong; Kwon, Jung Hwan [Korea University, Seoul (Korea, Republic of); Lee, Kyu Hong [Korea Institute of Toxicology, Jeongeup (Korea, Republic of)

2015-07-15

Fatalities caused by the use of polyhexamethylene guanidine (PHMG), a general-purpose chemical germicide used as a humidifier disinfectant in Korea, have raised concerns about exposure to biocide aerosols in indoor environments. A sampler capable of accumulating PHMG from aqueous aerosols was developed as an alternative to low-volume air samplers. This sampler was prepared by placing glass beads coated with 2-(2,4,5,7-tetrabromo-6-oxido-3-oxo-3H-xanthen-9-yl)benzoate (Eosin Y) in a custom-made plastic holder. Passive sampling rates, measured in a bench-top exposure chamber at two different aqueous PHMG aerosol generation rates, were found to be independent of the experimental conditions. This suggests that the capacity of the sampler to accumulate the PHMG aerosol was sufficient for the sampling duration tested. However, the passive sampling rate was 7.6 × 10{sup −6} m{sup 3}/h for the sampler area of 22 cm{sup 2}. This rate is lower than the typical human breathing rate and inadequate for quantitative instrumental analyses at low concentrations in indoor air. A 30-fold enhancement of the sampling rate was achieved by forced convection using a commercial battery-operated fan at ≥2000 rpm. With this accelerated sampling rate, the sampler could be used to monitor time-integrated concentrations of PHMG aerosols in the air.

Nano-magnetic particles used in biomedicine: core and coating materials.

Science.gov (United States)

Karimi, Z; Karimi, L; Shokrollahi, H

2013-07-01

Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine. Copyright © 2013 Elsevier B.V. All rights reserved.

Electron beam curable branched chain polyurethane acrylates for magnetic media coatings

International Nuclear Information System (INIS)

Ukachi, Takashi; Haga, Kei-ichi; Matsumura, Yoshio

1989-01-01

Electron beam curable binder resins have been studied to realize the high quality magnetic coatings. It was supposed that resins with a higher crosslink density could lead to magnetic coatings with higher abrasion resistance. Branched chain polyurethane acrylates show a higher degree of cure by irradiation with an electron beam in comparison with linear polyurethane acrylates. This paper describes the potential wear resistance between properties of magnetic coatings and the physical properties of the cured unpigmented branched chain polyurethane acrylates that were used as the binder resins. (author)

Fluorescent Quantification of DNA Based on Core-Shell Fe3O4@SiO2@Au Nanocomposites and Multiplex Ligation-Dependent Probe Amplification.

Science.gov (United States)

Fan, Jing; Yang, Haowen; Liu, Ming; Wu, Dan; Jiang, Hongrong; Zeng, Xin; Elingarami, Sauli; Ll, Zhiyang; Li, Song; Liu, Hongna; He, Nongyue

2015-02-01

In this research, a novel method for relative fluorescent quantification of DNA based on Fe3O4@SiO2@Au gold-coated magnetic nanocomposites (GMNPs) and multiplex ligation- dependent probe amplification (MLPA) has been developed. With the help of self-assembly, seed-mediated growth and chemical reduction method, core-shell Fe3O4@SiO2@Au GMNPs were synthesized. Through modified streptavidin on the GMNPs surface, we obtained a bead chip which can capture the biotinylated probes. Then we designed MLPA probes which were tagged with biotin or Cy3 and target DNA on the basis of human APP gene sequence. The products from the thermostable DNA ligase induced ligation reactions and PCR amplifications were incubated with SA-GMNPs. After washing, magnetic separation, spotting, the fluorescent scanning results showed our method can be used for the relative quantitative analysis of the target DNA in the concentration range of 03004~0.5 µM.

On-bead combinatorial synthesis and imaging of chemical exchange saturation transfer magnetic resonance imaging agents to identify factors that influence water exchange.

Science.gov (United States)

Napolitano, Roberta; Soesbe, Todd C; De León-Rodríguez, Luis M; Sherry, A Dean; Udugamasooriya, D Gomika

2011-08-24

The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid, economical on-bead combinatorial synthesis of a library of imaging agents. Eighty different 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid (DOTA)-tetraamide peptoid derivatives were prepared on beads using a variety of charged, uncharged but polar, hydrophobic, and variably sized primary amines. A single chemical exchange saturation transfer image of the on-bead library easily distinguished those compounds having the most favorable water exchange kinetics. This combinatorial approach will allow rapid screening of libraries of imaging agents to identify the chemical characteristics of a ligand that yield the most sensitive imaging agents. This technique could be automated and readily adapted to other types of MRI or magnetic resonance/positron emission tomography agents as well.

Fabrication of a pen-shaped portable biochemical reaction system based on magnetic bead manipulation

International Nuclear Information System (INIS)

Shikida, Mitsuhiro; Inagaki, Noriyuki; Okochi, Mina; Honda, Hiroyuki; Sato, Kazuo

2011-01-01

A pen-shaped platform that is similar to a mechanical pencil is proposed for producing a portable reaction system. A reaction unit, as the key component in the system, was produced by using a heat shrinkable tube. A mechanical pencil supplied by Mitsubishi Pencil Co. Ltd was used as the pen-shaped platform for driving the reaction cylinder. It was actuated using an inchworm motion. We confirmed that the magnetic beads were successfully manipulated in the droplet in the cylinder-shaped reaction units. (technical note)

Multi-layered electroless Ni-P coatings on powder-sintered Nd-Fe-B permanent magnet

International Nuclear Information System (INIS)

Chen Zhong; Ng, Alice; Yi Jianzhang; Chen Xingfu

2006-01-01

This paper has shown a successful protective coating scheme for powder-sintered Nd-Fe-B permanent magnet using multi-layered electroless nickel (EN) deposition. A low-phosphorus nickel layer is plated with an alkaline EN solution first, followed by a high-phosphorus nickel layer plated with an acidic solution. An additional topcoat by medium-phosphorus nickel on the high-phosphorus coating is also explored. It is shown that the high-phosphorus nickel layer coated in acidic solution provides the best corrosion protection because of its dense amorphous structure. The medium phosphorus topcoat is also dense and is able to provide reasonable corrosion resistance. The low-phosphorus layer itself does not have enough corrosion resistance; its main role is to provide an intermediate coating on the powder-sintered magnet. X-ray diffraction measurement shows that the low-phosphorus coating consists of nano-crystallines, and the high- and the medium-phosphorus coatings are dominated by amorphous structure. Microscopic observation and scratch test on these composite coatings demonstrate good adhesion between the magnet and the coatings. Remanence and coercivity of the plated magnet decrease with the applied coatings, but measured values are still very attractive for practical applications among known hard magnets

Heating ability and biocompatibility study of silica-coated magnetic ...

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 38; Issue 6. Heating ability and biocompatibility study of silica-coated magnetic nanoparticles as heating mediators for magnetic hyperthermia and magnetically triggered drug delivery systems. Meysam Soleymani Mohammad Edrissi. Volume 38 Issue 6 October 2015 ...

[The cytotoxicity of N48 NdFeB magnets coated with titanium-nitride].

Science.gov (United States)

Cao, Xiao-Ming; Hou, Zhi-Ming; Chu, Ming

2008-04-01

To evaluate the effect of N48 NdFeB magnets coated with titanium-nitride on the growth and apoptosis of L929 mouse fibroblast cells, and to determine the material biocompatibility. The NdFeB magnets coated with titanium-nitride, bare NdFeB magnets and ordinary brackets were put into RPMI-1640 to prepare fusions. L929 mouse fibroblast cells were cultivated in the negative control liquid, positive control liquid, 100%, 50% and 25% sample fusions, respectively. The cell proliferation vitality was detected by MTT assay and the relative growth rate was calculated.Cell scatter diagrams of the negative control liquid, 100% titanium-nitride coated magnets fusion and bare magnets fusion were detected by flow cytometry Annexin V/PI double staining method. The ratios of normal cells, early apoptosis, advanced apoptosis and necrosis cells were calculated. The results were analyzed for paired t test using SPSS11.5 software package. The toxic levels of N48 NdFeB coated with titanium-nitride were ranked as 0-1. The toxic levels of bare magnets were ranked as 2. The cell scatter diagrams showed that there was no significant difference in living cell, early apoptosis and necrosis between magnets coated with titanium-nitride and control group. But there was significant difference between the bare magnets group and control group. The N48 NdFeB magnets coated with titanium-nitride have good biocompatibility.

A Magnetic Sensor System for Biological Detection

KAUST Repository

Li, Fuquan

2015-05-01

Magnetic biosensors detect biological targets through sensing the stray field of magnetic beads which label the targets. Commonly, magnetic biosensors employ the “sandwich” method to immobilize biological targets, i.e., the targets are sandwiched between a bio-functionalized sensor surface and bio-functionalized magnetic beads. This method has been used very successfully in different application, but its execution requires a rather elaborate procedure including several washing and incubation steps. This dissertation investigates a new magnetic biosensor concept, which enables a simple and effective detection of biological targets. The biosensor takes advantage of the size difference between bare magnetic beads and compounds of magnetic beads and biological targets. First, the detection of super-paramagnetic beads via magnetic tunnel junction (MTJ) sensors is implemented. Frequency modulation is used to enhance the signal-to-noise ratio, enabling the detection of a single magnetic bead. Second, the concept of the magnetic biosensor is investigated theoretically. The biosensor consists of an MTJ sensor, which detects the stray field of magnetic beads inside of a trap on top of the MTJ. A microwire between the trap and the MTJ is used to attract magnetic beads to the trapping well by applying a current to it. The MTJ sensor’s output depends on the number of beads inside the trap. If biological targets are in the sample solution, the beads will form bead compounds consisting of beads linked to the biological targets. Since bead compounds are larger than bare beads, the number of beads inside the trapping well will depend on the presence of biological targets. Hence, the output of the MTJ sensor will depend on the biological targets. The dependences of sensor signals on the sizes of the MTJ sensor, magnetic beads and biological targets are studied to find the optimum constellations for the detection of specific biological targets. The optimization is demonstrated

TiO₂ beads and TiO₂-chitosan beads for urease immobilization.

Science.gov (United States)

Ispirli Doğaç, Yasemin; Deveci, Ilyas; Teke, Mustafa; Mercimek, Bedrettin

2014-09-01

The aim of the present study is to synthesize TiO2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO2 beads. In the first method (A), urease enzyme was immobilized onto TiO2 beads by adsorption and then crosslinking. In the second method (B), TiO2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5mg/ml for A and 1.0mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60°C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70°C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30°C (A), 40°C (B) and 35°C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65°C. However, at this temperature free urease protected only 15% activity. Copyright © 2014 Elsevier B.V. All rights reserved.

Binding kinetics of magnetic nanoparticles on latex beads and yeast cells studied by magnetorelaxometry

International Nuclear Information System (INIS)

Eberbeck, Dietmar; Bergemann, Christian; Hartwig, Stefan; Steinhoff, Uwe; Trahms, Lutz

2005-01-01

The ion exchange mediated binding of magnetic nanoparticles (MNP) to modified latex spheres and yeast cells was quantified using magnetorelaxometry. By fitting subsequently recorded relaxation curves, the kinetics of the binding reactions was extracted. The signal of MNP with weak ion exchanger groups bound to latex and yeast cells scales linearly with the concentration of latex beads or yeast cells whereas that of MNP with strong ion exchanger groups is proportional to the square root of concentration. The binding of the latter leads to a much stronger aggregation of yeast cells than the former MNP

Measurement of transverse Jc profiles of coated conductors using a magnetic knife of permanent magnets

Energy Technology Data Exchange (ETDEWEB)

Haenisch, J [Los Alamos National Laboratory; Mueller, F M [Los Alamos National Laboratory; Ashworth, S P [Los Alamos National Laboratory; Coulter, J Y [Los Alamos National Laboratory; Matias, Vlad [Los Alamos National Laboratory

2008-01-01

The transverse J{sub c} distribution in YBCO coated conductors was measured non-destructively with high resolution using a 'magnetic knife' made of permanent magnets. The method utilizes the strong depression of J{sub c} in applied magnetic fields. A narrow region of low (including zero) magnetic field, in a surrounding higher field, is moved transversely across the sample in order to reveal the critical-current density distribution. The net resolution of this device is approximately 65 {micro}m, and the J{sub c} resolution is better than 0.5%. A Fourier series inversion process was used to determine the transverse J{sub c} distribution in the sample. The J{sub c} profile was correlated with other sample properties of coated conductors prepared by pulsed laser deposition. Because of its straight-forward and inexpensive design, this J{sub c} imaging technique can be a powerful tool for quality control in coated-conductor production.

Magnetic bead purification of labeled DNA fragments forhigh-throughput capillary electrophoresis sequencing

Energy Technology Data Exchange (ETDEWEB)

Elkin, Christopher; Kapur, Hitesh; Smith, Troy; Humphries, David; Pollard, Martin; Hammon, Nancy; Hawkins, Trevor

2001-09-15

We have developed an automated purification method for terminator sequencing products based on a magnetic bead technology. This 384-well protocol generates labeled DNA fragments that are essentially free of contaminates for less than $0.005 per reaction. In comparison to laborious ethanol precipitation protocols, this method increases the phred20 read length by forty bases with various DNA templates such as PCR fragments, Plasmids, Cosmids and RCA products. Our method eliminates centrifugation and is compatible with both the MegaBACE 1000 and ABIPrism 3700 capillary instruments. As of September 2001, this method has produced over 1.6 million samples with 93 percent averaging 620 phred20 bases as part of Joint Genome Institutes Production Process.

Parallel RNA extraction using magnetic beads and a droplet array.

Science.gov (United States)

Shi, Xu; Chen, Chun-Hong; Gao, Weimin; Chao, Shih-Hui; Meldrum, Deirdre R

2015-02-21

Nucleic acid extraction is a necessary step for most genomic/transcriptomic analyses, but it often requires complicated mechanisms to be integrated into a lab-on-a-chip device. Here, we present a simple, effective configuration for rapidly obtaining purified RNA from low concentration cell medium. This Total RNA Extraction Droplet Array (TREDA) utilizes an array of surface-adhering droplets to facilitate the transportation of magnetic purification beads seamlessly through individual buffer solutions without solid structures. The fabrication of TREDA chips is rapid and does not require a microfabrication facility or expertise. The process takes less than 5 minutes. When purifying mRNA from bulk marine diatom samples, its repeatability and extraction efficiency are comparable to conventional tube-based operations. We demonstrate that TREDA can extract the total mRNA of about 10 marine diatom cells, indicating that the sensitivity of TREDA approaches single-digit cell numbers.

AC magnetization loss characteristics of HTS coated-conductors with magnetic substrates

International Nuclear Information System (INIS)

Tsukamoto, O.; Liu, M.; Odaka, S.; Miyagi, D.; Ohmatsu, K.

2007-01-01

AC magnetization loss characteristics of an HTS coated tape conductor with magnetic substrate subjected to an external AC magnetic field were investigated. The external magnetic field was perpendicular or parallel to the wide face of the tape conductor. Magnetization losses in the conductor and in the magnetic substrate itself without the superconductor layer, were measured by electric and calorimetric methods. The influence of the magnetic property of the substrate was strongly dependent on the direction of the external magnetic field. When the external magnetic field was perpendicular, magnetic property of the substrate did not affect the magnetization loss characteristics. This result suggests that the magnetization losses can be reduced by subdivisions of the superconducting layers even in the case of magnetic substrate conductors. When the external magnetic field was parallel, the magnetization losses were dominated by the losses in the magnetic substrate. Therefore, to reduce the magnetization losses in this case, reduction of magnetization losses in the substrate is necessary

Fabrication of magnetic alginate beads with uniform dispersion of CoFe{sub 2}O{sub 4} by the polydopamine surface functionalization for organic pollutants removal

Energy Technology Data Exchange (ETDEWEB)

Li, Xiaoli, E-mail: lixiaoli@lzu.edu.cn [Gansu Key Laboratory for Environmental Pollution Prediction and Control, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Lu, Haijun, E-mail: 784616040@qq.com [Gansu Key Laboratory for Environmental Pollution Prediction and Control, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Zhang, Yun, E-mail: zhangyun@lzu.edu.cn [Institute of Biochemical Engineering & Environmental Technology, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); He, Fu, E-mail: hef15@lzu.edu.cn [Institute of Biochemical Engineering & Environmental Technology, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Jing, Lingyun, E-mail: jingly12@lzu.edu.cn [Gansu Key Laboratory for Environmental Pollution Prediction and Control, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); He, Xinghua, E-mail: 466410250@qq.com [Institute of Biochemical Engineering & Environmental Technology, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

2016-12-15

Highlights: • SA@CoFe{sub 2}O{sub 4}-PDA with magnetic particles and biopolymers were used for dye removal. • SA@CoFe{sub 2}O{sub 4}-PDA exhibited the synergistic effect. • High adsorption capacities and fast kinetics were obtained. • Cationic dyes could be removed with high efficiency in a wide pH range. • Possible mechanism of adsorption was investigated. - Abstract: A simple and efficient method for production of magnetic composites by decorating CoFe{sub 2}O{sub 4} with polydopamine (PDA) through oxidative polymerization of dopamine was conducted. Further, magnetic alginate beads with porous structure containing well-dispersed CoFe{sub 2}O{sub 4}-PDA were fabricated by ionic crosslinking technology. The resulting SA@CoFe{sub 2}O{sub 4}-PDA beads were characterized using scanning electron microscopy, Fourier transform infrared spectrometry, X-ray diffractometer, vibrating sample magnetometer and X-ray photoelectron spectroscopy. Adsorption potential of SA@CoFe{sub 2}O{sub 4}-PDA beads for organic dyes including Methylene Blue (MB), Crystal Violet (CV) and Malachite Green (MG) was evaluated. SA@CoFe{sub 2}O{sub 4}-PDA beads exhibited excellent adsorption performances due to the composite effect, large surface area and porous structure. Organic dyes could be removed from water solution with high efficiency in a wide pH range of 4.0–9.0. Moreover, it exhibited much higher adsorptivity towards MB and CV with the maximum adsorption capacities of 466.60 and 456.52 mg/g, respectively, which were much higher than that of MG (248.78 mg/g). Ca-electrolyte had obvious adverse effects on MB and CV adsorption than MG. FTIR and XPS demonstrated that carboxylate, catechol, hydroxyl and amine groups might be involved in adsorption of organic dyes. The characteristics of wide pH range, high adsorption capacity and convenient magnetic separation would make SA@CoFe{sub 2}O{sub 4}-PDA beads as effective adsorbent for removal of organic dyes from wastewater.

Improving surface-enhanced Raman scattering effect using gold-coated hierarchical polystyrene bead substrates modified with postgrowth microwave treatment.

Science.gov (United States)

Yuen, Clement; Zheng, Wei; Huang, Zhiwei

2008-01-01

We report a novel postgrowth microwave heating implementation by selectively modifying hierarchical polystyrene (PS) bead substrates coated with gold (Au) films to effectively improve the surface-enhanced Raman scattering (SERS) effect on the analytes. The SERS signal of probe molecule rhodamine 6G (Rh 6G) on the microwave-treated Au-PS substrates can be improved by 10-fold, while the detection limit of Rh 6G in concentration can be enhanced by two orders of magnitude compared to the as-growth substrates. The high-quality SERS spectrum of saliva can also be acquired using the modified substrates, demonstrating the potential for the realization of the high-performance SERS substrates for biomedical applications.

Structure and properties of bulk amorphous magnetically soft coatings prepared by plasma spraying

International Nuclear Information System (INIS)

Kalita, V.I.; Kekalo, I.B.; Komlev, D.I.; Taranichev, V.E.

1995-01-01

Co-Ni-Fe-Si-B composition plasma coatings consisting of amorphous disk-shaped particles forming the bulk of a coating, of crystalline particles and of a threshold space, were studied. Iron and metalloid distribution heterogeneous by the thickness represents a peculiar feature for coating amorphous particles. Structure of coatings and their magnetic properties depend on some technological parameters. Conclusion is made that at annealing the variation of magnetic properties is determined by the processes of directed ordering and stratification of amorphous phase, while the low level of the initial magnetic properties of coatings is caused alongside with structure peculiarities, by occurrence of independent fine-dispersive domain structure in each disk-shaped amorphous phase. 14 refs., 8 figs., 6 tabs

Simulation of non-linear coaxial line using ferrite beads

International Nuclear Information System (INIS)

Furuya, S.; Matsumoto, H.; Tachi, K.; Takano, S.; Irisawa, J.

2002-01-01

A ferrite sharpener is a non-linear coaxial line using ferrite beads, which produces high-voltage, high-dV/dt pulses. We have been examining the characteristics of ferrite sharpeners experimentally, varying various parameters. Also we have made the simulation of the ferrite sharpener and compared the predictions with the experimental results in detail to analyze the characteristics of the sharpener. In this report, calculating the magnetization M of the ferrite bead, we divide the bead into n sections radially instead of adopting M at the average radius in the previous report. (author)

A planar conducting micro-loop structure for transportation of magnetic beads: An approach towards rapid sensing and quantification of biological entities

KAUST Repository

Gooneratne, Chinthaka Pasan; Giouroudi, Ioanna; Kosel, Jü rgen

2012-01-01

tools for accurate and rapid cell sorting and counting. Effective manipulation of beads is a critical factor for the performance of LOC devices. In this paper we propose a planar conducting micro-loop structure to trap, manipulate and transport magnetic

TiO2 beads and TiO2-chitosan beads for urease immobilization

International Nuclear Information System (INIS)

Ispirli Doğaç, Yasemin; Deveci, İlyas; Teke, Mustafa; Mercimek, Bedrettin

2014-01-01

The aim of the present study is to synthesize TiO 2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO 2 beads. In the first method (A), urease enzyme was immobilized onto TiO 2 beads by adsorption and then crosslinking. In the second method (B), TiO 2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2 mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5 mg/ml for A and 1.0 mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0 mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4–70 °C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30 °C (A), 40 °C (B) and 35 °C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65 °C. However, at this temperature free urease protected only 15% activity. - Highlights: • TiO 2 and TiO 2 -chitosan beads for urease immobilization have been prepared and characterized. • The beads used in this work are good matrices for the immobilization of urease. • The immobilized urease was shown to have good properties and stabilities (pH and thermal stability, operational stability). • The 50

Quantitative and multiplexed detection for blood typing based on quantum dot-magnetic bead assay.

Science.gov (United States)

Xu, Ting; Zhang, Qiang; Fan, Ya-Han; Li, Ru-Qing; Lu, Hua; Zhao, Shu-Ming; Jiang, Tian-Lun

2017-01-01

Accurate and reliable blood grouping is essential for safe blood transfusion. However, conventional methods are qualitative and use only single-antigen detection. We overcame these limitations by developing a simple, quantitative, and multiplexed detection method for blood grouping using quantum dots (QDs) and magnetic beads. In the QD fluorescence assay (QFA), blood group A and B antigens were quantified using QD labeling and magnetic beads, and the blood groups were identified according to the R value (the value was calculated with the fluorescence intensity from dual QD labeling) of A and B antigens. The optimized performance of QFA was established by blood typing 791 clinical samples. Quantitative and multiplexed detection for blood group antigens can be completed within 35 min with more than 10 5 red blood cells. When conditions are optimized, the assay performance is satisfactory for weak samples. The coefficients of variation between and within days were less than 10% and the reproducibility was good. The ABO blood groups of 791 clinical samples were identified by QFA, and the accuracy obtained was 100% compared with the tube test. Receiver-operating characteristic curves revealed that the QFA has high sensitivity and specificity toward clinical samples, and the cutoff points of the R value of A and B antigens were 1.483 and 1.576, respectively. In this study, we reported a novel quantitative and multiplexed method for the identification of ABO blood groups and presented an effective alternative for quantitative blood typing. This method can be used as an effective tool to improve blood typing and further guarantee clinical transfusion safety.

Design and synthesis of biotin analogues reversibly binding with streptavidin.

Science.gov (United States)

Yamamoto, Tomohiro; Aoki, Kiyoshi; Sugiyama, Akira; Doi, Hirofumi; Kodama, Tatsuhiko; Shimizu, Yohei; Kanai, Motomu

2015-04-01

Two new biotin analogues, biotin carbonate 5 and biotin carbamate 6, have been synthesized. These molecules were designed to reversibly bind with streptavidin by replacing the hydrogen-bond donor NH group(s) of biotin's cyclic urea moiety with oxygen. Biotin carbonate 5 was synthesized from L-arabinose (7), which furnishes the desired stereochemistry at the 3,4-cis-dihydroxy groups, in 11% overall yield (over 10 steps). Synthesis of biotin carbamate 6 was accomplished from L-cysteine-derived chiral aldehyde 33 in 11% overall yield (over 7 steps). Surface plasmon resonance analysis of water-soluble biotin carbonate analogue 46 and biotin carbamate analogue 47 revealed that KD values of these compounds for binding to streptavidin were 6.7×10(-6)  M and 1.7×10(-10)  M, respectively. These values were remarkably greater than that of biotin (KD =10(-15)  M), and thus indicate the importance of the nitrogen atoms for the strong binding between biotin and streptavidin. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sequential injection chemiluminescence immunoassay for nonionic surfactants by using magnetic microbeads

International Nuclear Information System (INIS)

Zhang Ruiq; Nakajima, Hizuru; Soh, Nobuaki; Nakano, Koji; Masadome, Takashi; Nagata, Kazumi; Sakamoto, Kazuhira; Imato, Toshihiko

2007-01-01

A rapid and sensitive immunoassay based on a sequential injection analysis (SIA) using magnetic microbeads for the determination of alkylphenol polyethoxylates (APnEOs) is described. An SIA system was constructed from a syringe pump, a switching valve, a flow-through type immunoreaction cell equipped with a photon counting unit and a neodymium magnet. Magnetic beads, to which an anti-APnEOs monoclonal antibody was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of the magnetic beads in and from the immunoreaction cell were controlled by means of a neodymium magnet and adjusting the flow of a carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an anti-APnEOs monoclonal antibody immobilized on the magnetic beads with a sample APnEOs and a horseradish peroxidase (HRP)-labeled APnEOs in the same sample solution, and was based on the subsequent chemiluminscence reaction of HRP on the magnetic microbeads with a luminol solution containing hydrogen peroxide and p-iodophenol. The anti-APnEOs antibody was immobilized on the magnetic microbeads by coupling the antibody with the magnetic beads after activation of a carboxylate moiety on the surface of the magnetic beads that had been coated with a polylactic acid film. The antibody immobilized magnetic beads were introduced in the immunoreaction cell and trapped in it by the neodymium magnet, which was equipped beneath the immunoreaction cell. An APnEOs sample solution containing the HRP-labeled APnEOs at a constant concentration, and a luminol solution containing hydrogen peroxide and p-iodophenol were sequentially introduced into the immunoreaction cell, according to an SIA programmed sequence. Chemiluminescence emission was monitored by means of a photon counting unit located at the upper side of the immunoreaction cell by collecting the emitted light with a lens. A typical sigmoidal calibration curve was obtained, when the logarithm

Construction and optimization of an efficient breathing-based isothermal emulsion amplification method

Energy Technology Data Exchange (ETDEWEB)

Shen, Yanting, E-mail: shenyanting798@126.com [Research Center for Learning Science, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); State Key Laboratory of Bioelectronics, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); Tian, Fei, E-mail: 642807827@qq.com [Research Center for Learning Science, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); Tu, Jing, E-mail: jtu@seu.edu.cn [State Key Laboratory of Bioelectronics, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); Li, Rui, E-mail: lirui901113@163.com [Research Center for Learning Science, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); Chen, Zhenzhu, E-mail: zzchen_seu@163.com [Research Center for Learning Science, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); Bai, Yunfei, E-mail: whitecf@seu.edu.cn [State Key Laboratory of Bioelectronics, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); Ge, Qinyu, E-mail: geqinyu@seu.edu.cn [State Key Laboratory of Bioelectronics, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China); Lu, Zuhong, E-mail: zhlu@seu.edu.cn [State Key Laboratory of Bioelectronics, Southeast University, Sipailou Road no. 2, Nanjing, Jiangsu Province 210096 (China)

2017-06-22

The reaction temperature is one of the main factors that affect the stability of emulsion PCR (emPCR). Focusing on this point, we applied the “DNA breathing” mechanism in BEAMing (Bead, Emulsion, Amplification, and Magnetic) and proposed a more stable emulsion amplification method. Compared to the conventional emPCR, this method provided excellent results. Firstly, more stable emulsion system resulted in higher percentage of single-molecular amplifications (73.17%). Secondly, an ordinary temperature-controlling device was enough. Our outcome showed that the reaction temperature of this method was not strict so that the ordinary temperature-controlling device was enough for it (the heat block sets vs. the PCR instrument: 13.140 ± 0.110 vs. 13.008 ± 0.039, P = 0.120). Thirdly, the single-biotinylated emP{sub 1} coated streptavidin beads were stable enough to be used for this method (the control temperature vs. the reaction temperature: 2967.91 ± 409.045 vs. 3026.22 ± 442.129, P = 0.334), which could replace the double-biotinylated emP{sub 1} coated beads and was benefit for saving cost. In conclusion, the method presented here with stable emulsion system, simplified temperature-controlling device, and decreased investment would be a highly streamlined and inexpensive option for future single-molecular amplification based researches. - Highlights: • A breathing-based isothermal emulsion amplification (BIEA) method was developed. • BIEA showed excellent properties compared with conventional amplification method. • Terminal breathing of DNA duplex was firstly used in emulsion amplification.

Monolayer-crystal streptavidin support films provide an internal standard of cryo-EM image quality

Energy Technology Data Exchange (ETDEWEB)

Han, Bong-Gyoon [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Watson, Zoe [Univ. of California, Berkeley, CA (United States); Cate, Jamie H. D. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Glaeser, Robert M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2017-03-01

Analysis of images of biotinylated Escherichia coli 70S ribosome particles, bound to streptavidin affinity grids, demonstrates that the image-quality of particles can be predicted by the image-quality of the monolayer crystalline support film. Also, the quality of the Thon rings is a good predictor of the image-quality of particles, but only when images of the streptavidin crystals extend to relatively high resolution. When the estimated resolution of streptavidin was 5 Å or worse, for example, the ribosomal density map obtained from 22,697 particles went to only 9.5 Å, while the resolution of the map reached 4.0 Å for the same number of particles, when the estimated resolution of streptavidin crystal was 4 Å or better. It thus is easy to tell which images in a data set ought to be retained for further work, based on the highest resolution seen for Bragg peaks in the computed Fourier transforms of the streptavidin component. The refined density map obtained from 57,826 particles obtained in this way extended to 3.6 Å, a marked improvement over the value of 3.9 Å obtained previously from a subset of 52,433 particles obtained from the same initial data set of 101,213 particles after 3-D classification. These results are consistent with the hypothesis that interaction with the air-water interface can damage particles when the sample becomes too thin. Finally, streptavidin monolayer crystals appear to provide a good indication of when that is the case.

Monodisperse measurement of the biotin-streptavidin interaction strength in a well-defined pulling geometry.

Directory of Open Access Journals (Sweden)

Steffen M Sedlak

Full Text Available The widely used interaction of the homotetramer streptavidin with the small molecule biotin has been intensively studied by force spectroscopy and has become a model system for receptor ligand interaction. However, streptavidin's tetravalency results in diverse force propagation pathways through the different binding interfaces. This multiplicity gives rise to polydisperse force spectroscopy data. Here, we present an engineered monovalent streptavidin tetramer with a single cysteine in its functional subunit that allows for site-specific immobilization of the molecule, orthogonal to biotin binding. Functionality of streptavidin and its binding properties for biotin remain unaffected. We thus created a stable and reliable molecular anchor with a unique high-affinity binding site for biotinylated molecules or nanoparticles, which we expect to be useful for many single-molecule applications. To characterize the mechanical properties of the bond between biotin and our monovalent streptavidin, we performed force spectroscopy experiments using an atomic force microscope. We were able to conduct measurements at the single-molecule level with 1:1-stoichiometry and a well-defined geometry, in which force exclusively propagates through a single subunit of the streptavidin tetramer. For different force loading rates, we obtained narrow force distributions of the bond rupture forces ranging from 200 pN at 1,500 pN/s to 230 pN at 110,000 pN/s. The data are in very good agreement with the standard Bell-Evans model with a single potential barrier at Δx0 = 0.38 nm and a zero-force off-rate koff,0 in the 10-6 s-1 range.

Monodisperse measurement of the biotin-streptavidin interaction strength in a well-defined pulling geometry.

Science.gov (United States)

Sedlak, Steffen M; Bauer, Magnus S; Kluger, Carleen; Schendel, Leonard C; Milles, Lukas F; Pippig, Diana A; Gaub, Hermann E

2017-01-01

The widely used interaction of the homotetramer streptavidin with the small molecule biotin has been intensively studied by force spectroscopy and has become a model system for receptor ligand interaction. However, streptavidin's tetravalency results in diverse force propagation pathways through the different binding interfaces. This multiplicity gives rise to polydisperse force spectroscopy data. Here, we present an engineered monovalent streptavidin tetramer with a single cysteine in its functional subunit that allows for site-specific immobilization of the molecule, orthogonal to biotin binding. Functionality of streptavidin and its binding properties for biotin remain unaffected. We thus created a stable and reliable molecular anchor with a unique high-affinity binding site for biotinylated molecules or nanoparticles, which we expect to be useful for many single-molecule applications. To characterize the mechanical properties of the bond between biotin and our monovalent streptavidin, we performed force spectroscopy experiments using an atomic force microscope. We were able to conduct measurements at the single-molecule level with 1:1-stoichiometry and a well-defined geometry, in which force exclusively propagates through a single subunit of the streptavidin tetramer. For different force loading rates, we obtained narrow force distributions of the bond rupture forces ranging from 200 pN at 1,500 pN/s to 230 pN at 110,000 pN/s. The data are in very good agreement with the standard Bell-Evans model with a single potential barrier at Δx0 = 0.38 nm and a zero-force off-rate koff,0 in the 10-6 s-1 range.

New advances in electrochemical biosensors for the detection of toxins: Nanomaterials, magnetic beads and microfluidics systems. A review

International Nuclear Information System (INIS)

Reverté, Laia; Prieto-Simón, Beatriz; Campàs, Mònica

2016-01-01

The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised. - Highlights: • Nanomaterials improve the performance of electrochemical biosensors. • Carbon nanomaterials can act as electrocatalysts or label supports in biosensors. • Metal nanomaterials can act as nanostructured supports or labels in biosensors. • Magnetic beads are exploited as immobilisation supports and/or label carriers.

New advances in electrochemical biosensors for the detection of toxins: Nanomaterials, magnetic beads and microfluidics systems. A review

Energy Technology Data Exchange (ETDEWEB)

Reverté, Laia [IRTA, Carretera Poble Nou km. 5.5, 43540 Sant Carles de la Ràpita, Tarragona (Spain); Prieto-Simón, Beatriz [ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute, University of South Australia, SA 5095 (Australia); Campàs, Mònica, E-mail: monica.campas@irta.cat [IRTA, Carretera Poble Nou km. 5.5, 43540 Sant Carles de la Ràpita, Tarragona (Spain)

2016-02-18

The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised. - Highlights: • Nanomaterials improve the performance of electrochemical biosensors. • Carbon nanomaterials can act as electrocatalysts or label supports in biosensors. • Metal nanomaterials can act as nanostructured supports or labels in biosensors. • Magnetic beads are exploited as immobilisation supports and/or label carriers.

Crystal structure of core streptavidin determined from multi-wavelength anomalous diffraction of synchrotron radiation

International Nuclear Information System (INIS)

Hendrickson, W.A.; Paehler, A.; Smith, J.L.; Satow, Y.; Merritt, E.A.; Phizackerley, R.P.

1989-01-01

A three-dimensional crystal structure of the biotin-binding core of streptavidin has been determined at 3.1-angstrom resolution. The structure was analyzed from diffraction data measured at three wavelengths from a single crystal of the selenobiotinyl complex with streptavidin. Streptavidin is a tetramer with subunits arrayed in D 2 symmetry. Each protomer is an 8-stranded β-barrel with simple up-down topology. Biotin molecules are bound at one end of each barrel. This study demonstrates the effectiveness of multi-wavelength anomalous diffraction (MAD) procedures for macromolecular crystallography and provides a basis for detailed study of biotin-avidin interactions

Simultaneous Determination of the Main Peanut Allergens in Foods Using Disposable Amperometric Magnetic Beads-Based Immunosensing Platforms

Directory of Open Access Journals (Sweden)

Víctor Ruiz-Valdepeñas Montiel

2016-06-01

Full Text Available In this work, a novel magnetic beads (MBs-based immunosensing approach for the rapid and simultaneous determination of the main peanut allergenic proteins (Ara h 1 and Ara h 2 is reported. It involves the use of sandwich-type immunoassays using selective capture and detector antibodies and carboxylic acid-modified magnetic beads (HOOC-MBs. Amperometric detection at −0.20 V was performed using dual screen-printed carbon electrodes (SPdCEs and the H2O2/hydroquinone (HQ system. This methodology exhibits high sensitivity and selectivity for the target proteins providing detection limits of 18.0 and 0.07 ng/mL for Ara h 1 and Ara h 2, respectively, with an assay time of only 2 h. The usefulness of the approach was evaluated by detecting the endogenous content of both allergenic proteins in different food extracts as well as trace amounts of peanut allergen (0.0001% or 1.0 mg/kg in wheat flour spiked samples. The developed platform provides better Low detection limits (LODs in shorter assay times than those claimed for the allergen specific commercial ELISA kits using the same immunoreagents and quantitative information on individual food allergen levels. Moreover, the flexibility of the methodology makes it readily translate to the detection of other food-allergens.

Electromagnetic field analyses of two-layer power transmission cables consisting of coated conductors with magnetic and non-magnetic substrates and AC losses in their superconductor layers

International Nuclear Information System (INIS)

Nakahata, Masaaki; Amemiya, Naoyuki

2008-01-01

Two-dimensional electromagnetic field analyses were undertaken using two representative cross sections of two-layer cables consisting of coated conductors with magnetic and non-magnetic substrates. The following two arrangements were used for the coated conductors between the inner and outer layers: (1) tape-on-tape and (2) alternate. The calculated magnetic flux profile around each coated conductor was visualized. In the case of the non-magnetic substrate, the magnetic field to which coated conductors in the outer layer are exposed contains more perpendicular component to the conductor wide face (perpendicular field component) when compared to that in the inner layer. On the other hand, for the tape-on-tape arrangement of coated conductors with a magnetic substrate, the reverse is true. In the case of the alternate arrangement of the coated conductor with a magnetic substrate, the magnetic field to which the coated conductors in the inner and outer layers are exposed experiences a small perpendicular field component. When using a non-magnetic substrate, the AC loss in the superconductor layer of the coated conductors in the two-layer cables is dominated by that in the outer layer, whereas the reverse is true in the case of a magnetic substrate. When comparing the AC losses in superconductor layers of coated conductors with non-magnetic and magnetic substrates in two-layer cables, the latter is larger than the former, but the influence of the magnetism of substrates on AC losses in superconductor layers is not remarkable

Functionality screen of streptavidin mutants by non-denaturing SDS-PAGE using biotin-4-fluorescein.

Science.gov (United States)

Humbert, Nicolas; Ward, Thomas R

2008-01-01

Site-directed mutagenesis or directed evolution of proteins often leads to the production of inactive mutants. For streptavidin and related proteins, mutations may lead to the loss of their biotin-binding properties. With high-throughput screening methodologies in mind, it is imperative to detect, prior to the high-density protein production, the bacteria that produce non-functional streptavidin isoforms. Based on the incorporation of biotin-4-fluorescein in streptavidin mutants present in Escherichia coli bacterial extracts, we detail a functional screen that allows the identification of biotin-binding streptavidin variants. Bacteria are cultivated in a small volume, followed by a rapid treatment of the cells; biotin-4-fluorescein is added to the bacterial extract and loaded on an Sodium Dodecyl Sulfate Poly-Acrylamide Gel Electrophoresis (SDS-PAGE) under non-denaturing conditions. Revealing is performed using a UV transilluminator. This screen is thus easy to implement, cheap and requires only readily available equipment.

Magnetic and microstructural properties of Fe{sub 3}O{sub 4}-coated Fe powder soft magnetic composites

Energy Technology Data Exchange (ETDEWEB)

Jo Sunday, Katie [Department of Materials Science and Engineering, Drexel University, Philadelphia, PA19104 (United States); Hanejko, Francis G. [Hoeganaes Corporation, Cinnaminson, NJ08077 (United States); Taheri, Mitra L., E-mail: mtaheri@coe.drexel.edu [Department of Materials Science and Engineering, Drexel University, Philadelphia, PA19104 (United States)

2017-02-01

Soft magnetic composites (SMCs) comprised of ferrite-coated ferrous powder permit isotropic magnetic flux capabilities, lower core losses, and complex designs through the use of traditional powder metallurgy techniques. Current coating materials and methods are vastly limited by the nonmagnetic properties of organic and some inorganic coatings and their inability to withstand high heat treatments for proper stress relief of core powder after compaction. Ferrite-based coatings are ferrimagnetic, highly resistive, and possess high melting temperatures, thus providing adequate electrical barriers between metallic particles. In this work, iron powder was coated with Fe{sub 3}O{sub 4} particles via mechanical milling, then compacted and cured in an inert gas environment. We find density and coercivity to improve with increasing temperatures; however, core loss greatly increases, which is attributed to the formation of a more conductive iron-oxide phase and less resistive Fe volume. Our work begins to exemplify the unique qualities and potential for ferrite-based coatings using traditional powder metallurgy techniques and higher curing temperatures for electromagnetic devices. - Highlights: • Fe{sub 3}O{sub 4}-coated Fe powder was produced via mechanical milling, then compacted and cured into composite form. • SEM/EDS confirm Fe particles are individually isolated with iron-oxide coating material. • Larger particle sizes show improved core loss and coercivity measurements. • We report good magnetic properties for compaction at 800 MPa and a curing temperature of 700 °C.

In Vitro Capture of Small Ferrous Particles with a Magnetic Filtration Device Designed for Intravascular Use with Intraarterial Chemotherapy: Proof-of-Concept Study.

Science.gov (United States)

Mabray, Marc C; Lillaney, Prasheel; Sze, Chia-Hung; Losey, Aaron D; Yang, Jeffrey; Kondapavulur, Sravani; Liu, Derek; Saeed, Maythem; Patel, Anand; Cooke, Daniel; Jun, Young-Wook; El-Sayed, Ivan; Wilson, Mark; Hetts, Steven W

2016-03-01

To establish that a magnetic device designed for intravascular use can bind small iron particles in physiologic flow models. Uncoated iron oxide particles 50-100 nm and 1-5 µm in size were tested in a water flow chamber over a period of 10 minutes without a magnet (ie, control) and with large and small prototype magnets. These same particles and 1-µm carboxylic acid-coated iron oxide beads were likewise tested in a serum flow chamber model without a magnet (ie, control) and with the small prototype magnet. Particles were successfully captured from solution. Particle concentrations in solution decreased in all experiments (P particles in water with a large magnet), 97% (50-100-nm particles in water with a small magnet), 99% (1-5-µm particles in water with a large magnet), 99% (1-5-µm particles in water with a small magnet), 95% (50-100-nm particles in serum with a small magnet), 92% (1-5-µm particles in serum with a small magnet), and 75% (1-µm coated beads in serum with a small magnet) lower compared with matched control runs. This study demonstrates the concept of magnetic capture of small iron oxide particles in physiologic flow models by using a small wire-mounted magnetic filter designed for intravascular use. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

Domain-wall dynamics in glass-coated magnetic microwires

International Nuclear Information System (INIS)

Varga, R.; Zhukov, A.; Usov, N.; Blanco, J.M.; Gonzalez, J.; Zhukova, V.; Vojtanik, P.

2007-01-01

Glass-coated magnetic microwires with positive magnetostriction show peculiar domain structure that consists mostly of one large domain with magnetization-oriented axially. It was shown that small closure domains appear at the end of the microwire in order to decrease the stray fields. As a result of such domain structure, the magnetization reversal in axial direction runs through the depinning of one of such closure domains and subsequent propagation of the corresponding domain wall. Quite unusual domain-wall (DW) dynamics of the DW propagation predicted previously from the theory has been found in such amorphous microwires. In this paper, we are dealing with the DW dynamics of glass-coated microwires with small positive magnetostriction. The DW damping coming from the structural relaxation dominates at low temperatures as a result of the decrease of the mobility of the structural atomic-level defects. Negative critical propagation field points to the possible DW propagation without applied magnetic field. Probable explanation could be in terms of the effective mass of the DW

A preparation method and effects of Al–Cr coating on NdFeB sintered magnets

International Nuclear Information System (INIS)

Zheng, Jingwu; Lin, Min; Xia, Qingping

2012-01-01

A 50 μm Al–Cr coating on NdFeB sintered magnets was prepared through dipping in solution, shaking dry and heating at 300 °C. The morphology and composition of the Al–Cr coating were investigated with scanning electron microscope, energy dispersive spectrometer and X-ray diffraction. The corrosion resistance of NdFeB sintered magnets with and without the Al–Cr coating was analyzed by normal salt spray, polarization curves and electrochemical impedance spectroscopy. The magnetic properties were measured with a hysteresis loop tracer. The results show that the Al–Cr coating forms an overlapping structure and Al flakes lie nearly parallel to the substrate, which improves the anticorrosion and increases normal salt spray test from 10 to 100 h. The corrosion potential of NdFeB sintered magnets with and without the Al–Cr coating moves positively from −0.67 to −0.48 V, which is in accordance with Nyquist and Bode plots. The Al–Cr coating has little influence on the magnetic properties of the NdFeB sintered magnets. - Highlights: ► The Al–Cr coating can be prepared by dipping in solution, shaking dry and heating. ► The coating morphology shows to be an intense overlapping structure. ► The barrier effect combines with passivation and cathodic protection. ► The anticorrosion abilities improve while magnetic properties change little. ► Compared with other surface treatments, this method is convenient and low cost.

Beads.

Science.gov (United States)

Weewish Tree, 1979

1979-01-01

Beads served both as ornaments and as a medium of exchange, and the Indians manufactured them from such natural sources as bones, stones, beans, nuts, animal teeth, and polished antlers. Even after the introduction of European glass beads, the Indians continued to make their favorite beads from the natural sources. (DS)

A streptavidin linker layer that functions after drying.

Science.gov (United States)

Xia, Nan; Shumaker-Parry, Jennifer S; Zareie, M Hadi; Campbell, Charles T; Castner, David G

2004-04-27

The ability of streptavidin (SA) to simultaneously bind four biotins is often used in linker layers, where a biotinylated molecule is linked to a biotin-functionalized surface via SA. For biosensor and array applications, it is desirable that the SA linker layer be stable to drying and rehydration. In this study it was observed that a significant decrease in binding capacity of a SA layer occurred when that layer was dried. For this study a SA linker layer was constructed by binding SA to a biotin-containing alkylthiolate monolayer (BAT/OEG) self-assembled onto gold. Its stability after drying was investigated using surface plasmon resonance (SPR). Approximately a quarter of the SA layer was removed from the BAT/OEG surface upon drying and rehydration, suggesting disruption of SA-biotin binding when dry. This resulted in the dried SA layer losing approximately 40% of its biotinylated ferritin (BF) binding capacity. Coating the layer with trehalose before drying was found to inhibit the loss of SA from the BAT/OEG surface. SPR showed that the trehalose-protected SA linker layer retained approximately 91% of its original BF binding capacity after drying and rehydration. Atomic force microscopy, which was used to image individual surface-bound SA and BF molecules, qualitatively confirmed these observations.

Sensitive detection of point mutation by electrochemiluminescence and DNA ligase-based assay

Science.gov (United States)

Zhou, Huijuan; Wu, Baoyan

2008-12-01

The technology of single-base mutation detection plays an increasingly important role in diagnosis and prognosis of genetic-based diseases. Here we reported a new method for the analysis of point mutations in genomic DNA through the integration of allele-specific oligonucleotide ligation assay (OLA) with magnetic beads-based electrochemiluminescence (ECL) detection scheme. In this assay the tris(bipyridine) ruthenium (TBR) labeled probe and the biotinylated probe are designed to perfectly complementary to the mutant target, thus a ligation can be generated between those two probes by Taq DNA Ligase in the presence of mutant target. If there is an allele mismatch, the ligation does not take place. The ligation products are then captured onto streptavidin-coated paramagnetic beads, and detected by measuring the ECL signal of the TBR label. Results showed that the new method held a low detection limit down to 10 fmol and was successfully applied in the identification of point mutations from ASTC-α-1, PANC-1 and normal cell lines in codon 273 of TP53 oncogene. In summary, this method provides a sensitive, cost-effective and easy operation approach for point mutation detection.

Increased osteoblast density in the presence of novel calcium phosphate coated magnetic nanoparticles

International Nuclear Information System (INIS)

Pareta, Rajesh A; Webster, Thomas J; Taylor, Erik

2008-01-01

Bone diseases (including osteoporosis, osteoarthritis and bone cancer) are of great concern to the medical world. Drugs are available to treat such diseases, but often these drugs are not specifically targeted to the site of the disease and, thus, lack an immediate directed therapeutic effect. The optimal drug delivery system should enhance healthy bone growth with high specificity to the site of bone disease. It has been previously shown that magnetic nanoparticles can be directed in the presence of a magnetic field to any part of the body, allowing for site-specific drug delivery and possibly an immediate increase in bone density. The objective of the present study was to build off of this evidence and determine the density of osteoblasts (bone forming cells) in the presence of various uncoated and coated magnetic nanoparticles that could eventually be used in drug delivery applications. Results showed that some magnetic nanoparticles (specifically, γ-Fe 2 O 3 ) significantly promoted osteoblast density (that is, cells per well) after 5 and 8 days of culture compared to controls (no particles). These magnetic nanoparticles were further coated with calcium phosphate (CaP; the main inorganic component of bone) to tailor them for treating various bone diseases. The coatings were conducted in the presence of either bovine serum albumin (BSA) or citric acid (CA) to reduce magnetic nanoparticle agglomeration, a common problem resulting from the use of nanoparticles which decreases their effectiveness. Results with these coatings showed that magnetic nanoparticles, specifically (γ-Fe 2 O 3 ), coated in the presence of BSA significantly increased osteoblast density compared to controls after 1 day. In this manner, this study provided unexpected evidence that CaP-coated γ-Fe 2 O 3 magnetic nanoparticles increased osteoblast density (compared to no particles) and, thus, should be further studied to treat numerous bone diseases

The growth speed of microtubules with XMAP215-coated beads coupled to their ends is increased by tensile force

Science.gov (United States)

Trushko, Anastasiya; Schäffer, Erik; Howard, Jonathon

2013-01-01

The generation of pulling and pushing forces is one of the important functions of microtubules, which are dynamic and polarized structures. The ends of dynamic microtubules are able to form relatively stable links to cellular structures, so that when a microtubule grows it can exert a pushing force and when it shrinks it can exert a pulling force. Microtubule growth and shrinkage are tightly regulated by microtubule-associated proteins (MAPs) that bind to microtubule ends. Given their localization, MAPs may be exposed to compressive and tensile forces. The effect of such forces on MAP function, however, is poorly understood. Here we show that beads coated with the microtubule polymerizing protein XMAP215, the Xenopus homolog of Dis1 and chTOG, are able to link stably to the plus ends of microtubules, even when the ends are growing or shrinking; at growing ends, the beads increase the polymerization rate. Using optical tweezers, we found that tensile force further increased the microtubule polymerization rate. These results show that physical forces can regulate the activity of MAPs. Furthermore, our results show that XMAP215 can be used as a handle to sense and mechanically manipulate the dynamics of the microtubule tip. PMID:23964126

EB curable wetting resins for magnetic media coatings

International Nuclear Information System (INIS)

Laskin, L.; Ansel, R.E.; Murray, K.P.; Schmid, S.R.

1984-01-01

The magnetic media industry is studying means to improve the recording density, durability, product uniformity and production efficiency and to reduce wetting agent migration in the magnetic film. The use of electron beam curable resin binders for magnetic coatings is one of the approaches being studied for this. This paper compares the wetting efficiencies of several electron beam curable systems with a conventional resin and a conventional wetting agent. In this study it has been demonstrated that EB resins can be designed to effect proper magnetic pigment dispersion

A preparation method and effects of Al-Cr coating on NdFeB sintered magnets

Energy Technology Data Exchange (ETDEWEB)

Zheng, Jingwu [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Lin, Min, E-mail: linm@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, 519 Road Zhuangshi, District Zhenghai, Ningbo 315201, People' s Republic of China (China); Xia, Qingping [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)

2012-11-15

A 50 {mu}m Al-Cr coating on NdFeB sintered magnets was prepared through dipping in solution, shaking dry and heating at 300 Degree-Sign C. The morphology and composition of the Al-Cr coating were investigated with scanning electron microscope, energy dispersive spectrometer and X-ray diffraction. The corrosion resistance of NdFeB sintered magnets with and without the Al-Cr coating was analyzed by normal salt spray, polarization curves and electrochemical impedance spectroscopy. The magnetic properties were measured with a hysteresis loop tracer. The results show that the Al-Cr coating forms an overlapping structure and Al flakes lie nearly parallel to the substrate, which improves the anticorrosion and increases normal salt spray test from 10 to 100 h. The corrosion potential of NdFeB sintered magnets with and without the Al-Cr coating moves positively from -0.67 to -0.48 V, which is in accordance with Nyquist and Bode plots. The Al-Cr coating has little influence on the magnetic properties of the NdFeB sintered magnets. - Highlights: Black-Right-Pointing-Pointer The Al-Cr coating can be prepared by dipping in solution, shaking dry and heating. Black-Right-Pointing-Pointer The coating morphology shows to be an intense overlapping structure. Black-Right-Pointing-Pointer The barrier effect combines with passivation and cathodic protection. Black-Right-Pointing-Pointer The anticorrosion abilities improve while magnetic properties change little. Black-Right-Pointing-Pointer Compared with other surface treatments, this method is convenient and low cost.

Gold-based optical biosensor for single-mismatched DNA detection using salt-induced hybridization

DEFF Research Database (Denmark)

Zhan, Zongrui; Ma, Xingyi; Cao, Cuong

2011-01-01

In this study, a gold nanoparticle (Au-NP)-based detection method for sensitive and specific DNA-based diagnostic applications is described. A sandwich format consisting of Au-NPs/DNA/PMP (Streptavidin-coated MagnetSphere Para-Magnetic Particles) was fabricated. PMPs captured and separated target...

AC magnetization loss characteristics of HTS striated coated conductors with magnetic substrates

International Nuclear Information System (INIS)

Tsukamoto, O; Alamgir, A K M; Sekizawa, S; Miyagi, D

2008-01-01

AC magnetization losses in subdivided CC (Coated Conductor) with magnetic substrate were experimentally investigated comparing with those in subdivided CC with non-magnetic substrate for an AC external magnetic field perpendicular to the wide face of the CC. It is well known that the subdivision is effective to reduce magnetization losses in CC with non-magnetic substrate. The experimental results show that the subdivision is also effective for the CC with magnetic substrate and that the level of reduction of the losses by the subdivisions is almost the same as that of non-magnetic substrate CCs. It is concluded from the experimental results that the magnetic property of the substrate does not affect the magnetization losses in the subdivided conductor in the range of the experiment where the amplitude of the AC external magnetic field is 0 ∼ 0.1 T and the frequency is 16 ∼ 86 Hz

AC magnetization loss characteristics of HTS striated coated conductors with magnetic substrates

Energy Technology Data Exchange (ETDEWEB)

Tsukamoto, O; Alamgir, A K M; Sekizawa, S [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa, 240-8501 (Japan); Miyagi, D [Okayama University, 1-1, Tsushima-Naka, 1-Chome, Okayama 700-8530 (Japan)], E-mail: Osami-t@ynu.ac.jp

2008-02-01

AC magnetization losses in subdivided CC (Coated Conductor) with magnetic substrate were experimentally investigated comparing with those in subdivided CC with non-magnetic substrate for an AC external magnetic field perpendicular to the wide face of the CC. It is well known that the subdivision is effective to reduce magnetization losses in CC with non-magnetic substrate. The experimental results show that the subdivision is also effective for the CC with magnetic substrate and that the level of reduction of the losses by the subdivisions is almost the same as that of non-magnetic substrate CCs. It is concluded from the experimental results that the magnetic property of the substrate does not affect the magnetization losses in the subdivided conductor in the range of the experiment where the amplitude of the AC external magnetic field is 0 {approx} 0.1 T and the frequency is 16 {approx} 86 Hz.

Microwave synthesis of gibberellin acid 3 magnetic molecularly imprinted polymer beads for the trace analysis of gibberellin acids in plant samples by liquid chromatography-mass spectrometry detection.

Science.gov (United States)

Zhang, Zhuomin; Tan, Wei; Hu, Yuling; Li, Gongke; Zan, Song

2012-02-21

In this study, novel GA3 magnetic molecularly imprinted polymer (mag-MIP) beads were synthesized by a microwave irradiation method, and the beads were applied for the trace analysis of gibberellin acids (GAs) in plant samples including rice and cucumber coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS). The microwave synthetic procedure was optimized in detail. In particular, the interaction between GA3 and functional monomers was further studied for the selection of the optimal functional monomers during synthesis. It can be seen that the interaction between GA3 and acrylamide (AM) finally selected was stronger than that between GA3 and other functional monomers. GA3 mag-MIP beads were characterized by a series of physical tests. GA3 mag-MIP beads had a porous and homogeneous surface morphology with stable chemical, thermal and magnetic properties. Moreover, GA3 mag-MIP beads demonstrated selective and specific absorption behavior for the target compounds during unsaturated extraction, which resulted in a higher extraction capacity (∼708.4 pmol for GA3) and selectivity than GA3 mag-non-imprinted polymer beads. Finally, an analytical method of GA3 mag-AM-MIP bead extraction coupled with HPLC-MS detection was established and applied for the determination of trace GA1, GA3, GA4 and GA7 in rice and cucumber samples. It was satisfactory that GA4 could be actually found to be 121.5 ± 1.4 μg kg(-1) in real rice samples by this novel analytical method. The recoveries of spiked rice and cucumber samples were found to be 76.0-109.1% and 79.9-93.6% with RSDs of 2.8-8.8% and 3.1-7.7% (n = 3), respectively. The proposed method is efficient and applicable for the trace analysis of GAs in complicated plant samples.

Multiplex detection of plant pathogens through the luminex magplex bead system

NARCIS (Netherlands)

Vlugt, van der R.A.A.; Raaij, van H.M.G.; Weerdt, de M.; Bergervoet, J.H.W.

2015-01-01

Here we describe a versatile multiplex method for both the serological and molecular detection of plant pathogens. The Luminex MagPlex bead system uses small paramagnetic microspheres (“beads”), either coated with specific antibodies or oligonucleotides, which capture respectively viruses and/or

Preparation and magnetic properties of Ni–P–La coating by electroless plating on silicon substrate

Energy Technology Data Exchange (ETDEWEB)

Gao, Yun [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Wang, Jihui, E-mail: jhwang@tju.edu.cn [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Yuan, Jing [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); College of Physics and Electronic Information Engineering, Qinghai University for Nationalities, Xining, Qinghai 810007 (China); Li, Haiqin [College of Physics and Electronic Information Engineering, Qinghai University for Nationalities, Xining, Qinghai 810007 (China)

2016-02-28

Graphical abstract: The content of Ni phase, which is the main ferromagnetic phase in Ni–P–La coating, is almost increased linearly with the concentration of La in plating solution. - Highlights: • The La element improves the magnetic properties of Ni–P–La coating. • Magnetism increases but the stability of bath decreases with La content and pH. • Coatings peel off at high temperature (≥80 °C) and magnetism is weak in short time. • The optimum is the La{sub 2}O{sub 3} of 10 mg L{sup −1}, pH of 5.0, temperature of 75 °C and time of 45 min. - Abstract: Ni–P–La coatings were prepared on Si substrate by electroless plating method under different La content, pH value, plating temperature and plating time. The surface morphology, chemical composition, structure and magnetic properties of coatings were observed and determined by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). The results showed that Ni–P–La coating is smooth and uniform with a cellular morphology grown in columnar manner. With the increase of La content, pH value and plating time, the thickness and saturation magnetization of coating are increased continuously, but the stability of plating bath is decreased greatly with La content and pH value. Under higher plating temperature, the thickness and saturation magnetization of coatings are obviously enhanced. But too high plating temperature is harmful to the plating bath and coating. The optimum plating conditions for Ni–P–La coating is La{sub 2}O{sub 3} addition of 10 mg L{sup −1}, pH value of 5.0, plating temperature of 75 °C and plating time of 45 min. The role of La element is to benefit the deposition of Ni element, promote the formation of Ni phase during the annealing process, and thus improve the magnetic properties of Ni–P–La coating.

Electrochemical analysis of gold-coated magnetic nanoparticles for detecting immunological interaction

International Nuclear Information System (INIS)

Pham, Thao Thi-Hien; Sim, Sang Jun

2010-01-01

An electrochemical impedance immunosensor was developed for detecting the immunological interaction between human immunoglobulin (IgG) and protein A from Staphylococcus aureus based on the immobilization of human IgG on the surface of modified gold-coated magnetic nanoparticles. The nanoparticles with an Au shell and Fe oxide cores were functionalized by a self-assembled monolayer of 11-mercaptoundecanoic acid. The electrochemical analysis was conducted on the modified magnetic carbon paste electrodes with the nanoparticles. The magnetic nanoparticles were attached to the surface of the magnetic carbon paste electrodes via magnetic force. The cyclic voltammetry technique and electrochemical impedance spectroscopy measurements of the magnetic carbon paste electrodes coated with magnetic nanoparticles-human IgG complex showed changes in its alternating current (AC) response both after the modification of the surface of the electrode and the addition of protein A. The immunological interaction between human IgG on the surface of the modified magnetic carbon paste electrodes and protein A in the solution could be successfully monitored.

Influence of coating on nanocrystalline magnetic properties during high temperature thermal ageing

Energy Technology Data Exchange (ETDEWEB)

Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

2017-05-15

Since their birth or mergence the late 1980s, the nanocrystalline ultrasoft magnetic materials are taking a great importance in power electronic systems conception. One of the main advantages that make them more attractive nowadays is their ability to be packaged since the reduction of the magnetostrictive constant to almost zero. In aircraft applications, due to the high component compactness and to their location (for example near the jet engine), the operating temperature increases and may reach easily 200 °C and more. Consequently, the magnetic thermal ageing may occur but is, unfortunately, weakly studied. This paper focuses on the influence of the coating (packaging type) on the magnetic nanocrystalline performances during a thermal ageing. This study is based on monitoring the magnetic characteristics of two types of nanocrystalline cores (naked and coated) during a thermal activated ageing (100, 150 and 200 °C). Based on a dedicated monitoring protocol, a large magnetic characterization has been done and analyzed. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The coating impacts drastically the magnetic properties during thermal ageing. • Irreversible ageing phenomena after the total coating breakage. • The deteriorations are related to the storage of the magnetoelastic anisotropy.

A Rapid Detection Method of Brucella with Quantum Dots and Magnetic Beads Conjugated with Different Polyclonal Antibodies

Science.gov (United States)

Song, Dandan; Qu, Xiaofeng; Liu, Yushen; Li, Li; Yin, Dehui; Li, Juan; Xu, Kun; Xie, Renguo; Zhai, Yue; Zhang, Huiwen; Bao, Hao; Zhao, Chao; Wang, Juan; Song, Xiuling; Song, Wenzhi

2017-03-01

Brucella spp. are facultative intracellular bacteria that cause zoonotic disease of brucellosis worldwide. Traditional methods for detection of Brucella spp. take 48-72 h that does not meet the need of rapid detection. Herein, a new rapid detection method of Brucella was developed based on polyclonal antibody-conjugating quantum dots and antibody-modified magnetic beads. First, polyclonal antibodies IgG and IgY were prepared and then the antibody conjugated with quantum dots (QDs) and immunomagnetic beads (IMB), respectively, which were activated by N-(3-dimethylaminopropyl)- N'-ethylcar-bodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to form probes. We used the IMB probe to separate the Brucella and labeled by the QD probe, and then detected the fluorescence intensity with a fluorescence spectrometer. The detection method takes 105 min with a limit of detection of 103 CFU/mL and ranges from 10 to 105 CFU/mL ( R 2 = 0.9983), and it can be well used in real samples.

Magnetic Beads Enhance Adhesion of NIH 3T3 Fibroblasts: A Proof-of-Principle In Vitro Study for Implant-Mediated Long-Term Drug Delivery to the Inner Ear.

Science.gov (United States)

Aliuos, Pooyan; Schulze, Jennifer; Schomaker, Markus; Reuter, Günter; Stolle, Stefan R O; Werner, Darja; Ripken, Tammo; Lenarz, Thomas; Warnecke, Athanasia

2016-01-01

Long-term drug delivery to the inner ear may be achieved by functionalizing cochlear implant (CI) electrodes with cells providing neuroprotective factors. However, effective strategies in order to coat implant surfaces with cells need to be developed. Our vision is to make benefit of electromagnetic field attracting forces generated by CI electrodes to bind BDNF-secreting cells that are labelled with magnetic beads (MB) onto the electrode surfaces. Thus, the effect of MB-labelling on cell viability and BDNF production were investigated. Murine NIH 3T3 fibroblasts-genetically modified to produce BDNF-were labelled with MB. Atomic force and bright field microscopy illustrated the internalization of MB by fibroblasts after 24 h of cultivation. Labelling cells with MB did not expose cytotoxic effects on fibroblasts and allowed adhesion on magnetic surfaces with sufficient BDNF release. Our data demonstrate a novel approach for mediating enhanced long-term adhesion of BDNF-secreting fibroblasts on model electrode surfaces for cell-based drug delivery applications in vitro and in vivo. This therapeutic strategy, once transferred to cells suitable for clinical application, may allow the biological modifications of CI surfaces with cells releasing neurotrophic or other factors of interest.

Magnetic Beads Enhance Adhesion of NIH 3T3 Fibroblasts: A Proof-of-Principle In Vitro Study for Implant-Mediated Long-Term Drug Delivery to the Inner Ear.

Directory of Open Access Journals (Sweden)

Pooyan Aliuos

Full Text Available Long-term drug delivery to the inner ear may be achieved by functionalizing cochlear implant (CI electrodes with cells providing neuroprotective factors. However, effective strategies in order to coat implant surfaces with cells need to be developed. Our vision is to make benefit of electromagnetic field attracting forces generated by CI electrodes to bind BDNF-secreting cells that are labelled with magnetic beads (MB onto the electrode surfaces. Thus, the effect of MB-labelling on cell viability and BDNF production were investigated.Murine NIH 3T3 fibroblasts-genetically modified to produce BDNF-were labelled with MB.Atomic force and bright field microscopy illustrated the internalization of MB by fibroblasts after 24 h of cultivation. Labelling cells with MB did not expose cytotoxic effects on fibroblasts and allowed adhesion on magnetic surfaces with sufficient BDNF release.Our data demonstrate a novel approach for mediating enhanced long-term adhesion of BDNF-secreting fibroblasts on model electrode surfaces for cell-based drug delivery applications in vitro and in vivo. This therapeutic strategy, once transferred to cells suitable for clinical application, may allow the biological modifications of CI surfaces with cells releasing neurotrophic or other factors of interest.

Engineering of a Bacillus subtilis strain with adjustable levels of intracellular biotin for secretory production of functional streptavidin.

Science.gov (United States)

Wu, Sau-Ching; Wong, Sui-Lam

2002-03-01

Streptavidin is a biotin-binding protein which has been widely used in many in vitro and in vivo applications. Because of the ease of protein recovery and availability of protease-deficient strains, the Bacillus subtilis expression-secretion system is an attractive system for streptavidin production. However, attempts to produce streptavidin using B. subtilis face the problem that cells overproducing large amounts of streptavidin suffer poor growth, presumably because of biotin deficiency. This problem cannot be solved by supplementing biotin to the culture medium, as this will saturate the biotin binding sites in streptavidin. We addressed this dilemma by engineering a B. subtilis strain (WB800BIO) which overproduces intracellular biotin. The strategy involves replacing the natural regulatory region of the B. subtilis chromosomal biotin biosynthetic operon (bioWAFDBIorf2) with an engineered one consisting of the B. subtilis groE promoter and gluconate operator. Biotin production in WB800BIO is induced by gluconate, and the level of biotin produced can be adjusted by varying the gluconate dosage. A level of gluconate was selected to allow enhanced intracellular production of biotin without getting it released into the culture medium. WB800BIO, when used as a host for streptavidin production, grows healthily in a biotin-limited medium and produces large amounts (35 to 50 mg/liter) of streptavidin, with over 80% of its biotin binding sites available for future applications.

Electroless Co–P-Carbon Nanotube composite coating to enhance magnetic properties of grain-oriented electrical steel

International Nuclear Information System (INIS)

Goel, Vishu; Anderson, Philip; Hall, Jeremy; Robinson, Fiona; Bohm, Siva

2016-01-01

The effect of Co–P-CNT coating on the magnetic properties of grain oriented electrical steel was investigated. To analyse the coating, Raman spectroscopy, Superconducting QUantum Interference Device (SQUID), single strip testing, Scanning Electron Microscopy (SEM) and talysurf surface profilometry were performed. Raman spectra showed the D and G band which corroborates the presence of Multi-Walled Carbon Nanotubes (MWCNT) in the coating. The magnetic nature of the coating was confirmed by SQUID results. Power loss results show an improvement ranging 13–15% after coating with Co–P-CNT. The resistivity of the coating was measured to be 10 4 µΩ cm. Loss separation graphs were plotted before and after coating to study the improvement in power loss. It was found that the coating helps in reducing the hysteresis loss. The thickness of the coating was found to be 414±40 nm. The surface profilometry results showed that the surface roughness improved after coating the sample. - Highlights: • Co–P-CNT coating on Fe–3%Si steel was able to reduce the power loss by 13–15%. • Co–P-CNT coating reduced the surface roughness and enhanced the magnetic properties. • The decrease in coating thickness increased the stacking factor. • The stacking factor was further improved by the magnetic nature of the coating.

Electroless Co–P-Carbon Nanotube composite coating to enhance magnetic properties of grain-oriented electrical steel

Energy Technology Data Exchange (ETDEWEB)

Goel, Vishu, E-mail: vishu.goel.nit@gmail.com [Wolfson Centre for Magnetics, Cardiff University, Cardiff CF243AA (United Kingdom); Anderson, Philip, E-mail: AndersonPI1@cf.ac.uk [Wolfson Centre for Magnetics, Cardiff University, Cardiff CF243AA (United Kingdom); Hall, Jeremy, E-mail: HallJP@cf.ac.uk [Wolfson Centre for Magnetics, Cardiff University, Cardiff CF243AA (United Kingdom); Robinson, Fiona, E-mail: fiona.cj.robinson@tatasteel.com [Cogent power Ltd., Newport NP19 0RB (United Kingdom); Bohm, Siva, E-mail: siva.bohm@tatasteel.com [IIT Bombay, Mumbai 400076 (India)

2016-06-01

The effect of Co–P-CNT coating on the magnetic properties of grain oriented electrical steel was investigated. To analyse the coating, Raman spectroscopy, Superconducting QUantum Interference Device (SQUID), single strip testing, Scanning Electron Microscopy (SEM) and talysurf surface profilometry were performed. Raman spectra showed the D and G band which corroborates the presence of Multi-Walled Carbon Nanotubes (MWCNT) in the coating. The magnetic nature of the coating was confirmed by SQUID results. Power loss results show an improvement ranging 13–15% after coating with Co–P-CNT. The resistivity of the coating was measured to be 10{sup 4} µΩ cm. Loss separation graphs were plotted before and after coating to study the improvement in power loss. It was found that the coating helps in reducing the hysteresis loss. The thickness of the coating was found to be 414±40 nm. The surface profilometry results showed that the surface roughness improved after coating the sample. - Highlights: • Co–P-CNT coating on Fe–3%Si steel was able to reduce the power loss by 13–15%. • Co–P-CNT coating reduced the surface roughness and enhanced the magnetic properties. • The decrease in coating thickness increased the stacking factor. • The stacking factor was further improved by the magnetic nature of the coating.

Effects of coating molecules on the magnetic heating properties of Au-Fe3O4 heterodimer nanoparticles

Science.gov (United States)

Yamamoto, Y.; Ogasawara, J.; Himukai, H.; Itoh, T.

2016-10-01

In this paper, we report the heating properties of gold-magnetite (Au-Fe3O4) heterodimer nanoparticles (NPs) subjected to an alternating magnetic field. The Au-Fe3O4 NPs coated with oleic acid and oleylamine (OA) were synthesized through a method that combines seed mediation and high-temperature decomposition. The coating was replaced with dimercaptosuccinic acid (DMSA) by the ligand-exchange method. The specific absorption rates (SARs) for the OA- and DMSA-coated Au-Fe3O4 NPs coated with OA and DMSA at room temperature were determined through the calorimetric and magnetometric methods. SAR depended on the square of the magnetic field H up to an H value of 4 kA/m. The absolute value of the SAR for DMSA-coated NPs is about fivefold higher than that of the OA-coated NPs. The AC magnetic hysteresis measurements showed the recovery of the magnetic volume and the decrease in the magnetic anisotropy of the DMSA-coated NPs relative to those of the OA-coated NPs. These results suggest that the protective agent influences the magnetic properties of magnetite NPs via gold NPs.

Structure and magnetic properties of iron-based soft magnetic composite with Ni-Cu-Zn ferrite-silicone insulation coating

Science.gov (United States)

Li, Wangchang; Wang, Wei; Lv, Junjun; Ying, Yao; Yu, Jing; Zheng, Jingwu; Qiao, Liang; Che, Shenglei

2018-06-01

This paper investigates the structure and magnetic properties of Ni-Cu-Zn ferrite-silicone coated iron-based soft magnetic composites (SMCs). Scanning electron microscopy coupled with a energy-dispersive spectroscopy (EDS) analysis revealed that the Ni-Cu-Zn ferrite and silicone resin were uniformly coated on the surface of iron powders. By controlling the composition of the coating layer, low total core loss of 97.7 mW/cm3 (eddy current loss of 48 mW/cm3, hysteresis loss of 49.7 mW/cm3, measured at 100 kHz and 0.02 T) and relatively high effective permeability of 72.5 (measured at 100 kHz) were achieved. In addition, the as-prepared SMCs displayed higher electrical resistivity, good magnetic characteristics over a wide range of frequencies (20-200 kHz) and ideal the D-C bias properties (more than 75% at H = 50 Oe). Furthermore, higher elastic modulus and hardness of SMCs, which means that the coating layer has good mechanical properties and is not easily damaged during the pressing process, were obtained in this paper. The results of this work indicate that the Ni-Cu-Zn ferrite-silicone coated SMCs have desirable properties which would make them suitable for application in the fields of the electric-magnetic switching devices, such as inductance coils, transformer cores, synchronous electric motors and resonant inductors.

Fundamentals of magnet-actuated droplet manipulation on an open hydrophobic surface†

Science.gov (United States)

Long, Zhicheng; Shetty, Abhishek M.; Solomon, Michael J.; Larson, Ronald G.

2010-01-01

We systematically investigate droplet movement, coalescence, and splitting on an open hydrophobic surface. These processes are actuated by magnetic beads internalized in an oil-coated aqueous droplet using an external magnet. Results are organized into an ‘operating diagram’ that describes regions of droplet stable motion, breakage, and release from the magnet. The results are explained theoretically with a simple model that balances magnetic, friction, and capillary-induced drag forces and includes the effects of particle type, droplet size, surrounding oil layer, surface tension, and viscosity. Finally, we discuss the implications of the results for the design of magnet-actuated droplet systems for applications such as nucleic acid purification, immunoassay and drug delivery. PMID:19458864

Trapping a magnetic field of 7.9 T using a bulk magnet fabricated from stack of coated conductors

International Nuclear Information System (INIS)

Tamegai, T.; Hirai, T.; Sun, Y.; Pyon, S.

2016-01-01

Highlight: • A bulk magnet is fabricated using double stack of coated conductors (CC). • Magneto-optical imaging of the CC confirmed its homogeneity. • The fabricated bulk magnet has successfully trapped a magnetic field of 7.9 T. • The trapped magnetic field is consistent with the magnetic induction calculated from J_c(B) characteristics of the CC. - Abstract: We have fabricated a bulk magnet using double stack, each 130 layers, of short segments of coated conductors (CCs). The bulk magnet is magnetized by field-cooling in a magnetic field of 9 T down to 4.2 K. After reducing the magnetic field down to zero, we have successfully trapped a magnetic field of 7.9 T at the centre of the double stack. The magnetic field profile of the bulk magnet is calculated by fully considering the J_c(B) characteristics of the short segment of the CC. The trapped magnetic field values measured by Hall probes at three locations near the centre of the double stacks agree reasonably well with the calculated magnetic induction.

Structure and superparamagnetic behaviour of magnetite nanoparticles in cellulose beads

Energy Technology Data Exchange (ETDEWEB)

Correa, Jose R., E-mail: correa@fq.uh.cu [Department of General Chemistry, Faculty of Chemistry, University of Havana, Zapata and G, Havana City 10400 (Cuba); Bordallo, Eduardo [Sugar Cane-Cellulose Research Center, Cuba-9, Quivican (Cuba); Canetti, Dora [Department of Inorganic Chemistry, Faculty of Chemistry, University of Havana, Zapata and G, Havana City 10400 (Cuba); Leon, Vivian [Sugar Cane-Cellulose Research Center, Cuba-9, Quivican (Cuba); Otero-Diaz, Luis C. [Department of Inorganic Chemistry-1, Complutense University of Madrid, Madrid 28040 (Spain); Electron Microscopy Center, Complutense University of Madrid, Madrid 28040 (Spain); Negro, Carlos [Chemical Engineering Department, Complutense University of Madrid, Madrid 28040 (Spain); Gomez, Adrian [Electron Microscopy Center, Complutense University of Madrid, Madrid 28040 (Spain); Saez-Puche, Regino [Department of Inorganic Chemistry-1, Complutense University of Madrid, Madrid 28040 (Spain)

2010-08-15

Superparamagnetic magnetite nanoparticles were obtained starting from a mixture of iron(II) and iron(III) solutions in a preset total iron concentration from 0.04 to 0.8 mol l{sup -1} with ammonia at 25 and 70 {sup o}C. The regeneration of cellulose from viscose produces micrometrical spherical cellulose beads in which synthetic magnetite were embedded. The characterization of cellulose-magnetite beads by X-ray diffraction, Scanning and Transmission Electron Microscopy and magnetic measurement is reported. X-ray diffraction patterns indicate that the higher is the total iron concentration and temperature the higher is the crystal size of the magnetite obtained. Transmission Electron Microscopy studies of cellulose-magnetite beads revealed the distribution of magnetite nanoparticles inside pores of hundred nanometers. Magnetite as well as the cellulose-magnetite composites exhibit superparamagnetic characteristics. Field cooling and zero field cooling magnetic susceptibility measurements confirm the superparamagnetic behaviour and the blocking temperature for the magnetite with a mean size of 12.5 nm, which is 200 K.

Magnetic field effects on coating deposition rate and surface morphology coatings using magnetron sputtering

International Nuclear Information System (INIS)

Yang, Yu-Sen; Huang, Wesley

2010-01-01

Chromium nitride coatings exhibit superior hardness, excellent wear and oxidation resistance, and are widely applied in the die and mold industries. The aim of this study was to investigate magnetic field effects on the deposition rate and surface morphology of chromium nitride coatings deposited by magnetron sputtering. Four types of magnetic field configurations, including the magnetron sputtering system, SNSN, SNNN, and intermediate magnetron modification, are discussed in this paper. SKD11 cold work die steel and a silicon (100) chip were used as substrates in the chromium nitride depositions. The process parameters, such as target current, substrate bias, and the distance between the substrate and target, are at fixed conditions, except for the magnetic arrangement type. The experimental results showed that the deposition rates of the four types of magnetic field configurations were 1.06, 1.38, 1.67 and 1.26 µm h −1 , respectively. In these cases, the SNNN type performs more than 58% faster than the unbalanced magnetron configuration does for the deposition rate. The surface morphology of chromium nitride films was also examined by SEM and is discussed in this paper

Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

Science.gov (United States)

Akbaba, Hasan; Karagöz, Uğur; Selamet, Yusuf; Kantarcı, A. Gülten

2017-03-01

The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15-17 emu g-1 for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting.

Synthesis and characterization of cationic lipid coated magnetic nanoparticles using multiple emulsions as microreactors

Energy Technology Data Exchange (ETDEWEB)

Akbaba, Hasan; Karagöz, Uğur [Ege University, Faculty of Pharmacy, Department of Pharmaceutical Biotechnology, 35100 Izmir (Turkey); Selamet, Yusuf [Izmir Institute of Technology, Faculty of Science, Department of Physics, 35433 Izmir (Turkey); Kantarcı, A. Gülten, E-mail: gulten.kantarci@ege.edu.tr [Ege University, Faculty of Pharmacy, Department of Pharmaceutical Biotechnology, 35100 Izmir (Turkey)

2017-03-15

The aim of this study was to develop a novel iron oxide nanoparticle synthesis method with in-situ surface coating. For this purpose multiple emulsions were used as microreactors for the first time and magnetic iron oxide particles synthesized in the core of cationic solid lipid nanoparticles. DLS, SEM, TEM, VSM, Raman Spectrometer, XRD, and XPS techniques were performed for characterization of the magnetic nanoparticles. Obtained magnetic nanoparticles are superparamagnetic and no additional process was needed for surface adjustments. They are positively charged as a result of cationic lipid coating and has appropriate particle size (<30 nm) for drug or nucleic acid delivery. Structure analysis showed that magnetic core material is in the form of magnetite. Saturation magnetization value was measured as 15–17 emu g{sup −1} for lipid coated magnetic nanoparticles obtained by multiple emulsion method which is reasonably sufficient for magnetic targeting. - Highlights: • A novel iron oxide nanoparticle synthesis method with in-situ surface coating. • Combining advantages of microemulsions and multiple emulsion methods. • Multiple emulsions were used as microreactors for magnetic nanoparticle synthesis. • Superparamagnetic iron oxide particles synthesized in the core of cationic lipids. • Possible delivery systems for nucleic acids, oil soluble compounds or drugs.

Magnetic anisotropy in rapidly quenched amorphous glass-coated nanowires

Energy Technology Data Exchange (ETDEWEB)

Óvári, T.-A.; Rotărescu, C.; Atițoaie, A.; Corodeanu, S.; Lupu, N., E-mail: nicole@phys-iasi.ro; Chiriac, H.

2016-07-15

Results on the roles played by the magnetoelastic and magnetostatic anisotropy terms in the magnetic behavior of glass-coated magnetostrictive amorphous nanowires prepared by means of rapid solidification are reported. Their contributions have been analyzed both experimentally, through hysteresis loop measurements, and theoretically, using micromagnetic simulations. All the investigated samples exhibit a magnetically bistable behavior, characterized by a single-step magnetization reversal when the applied field reaches a critical threshold value, called switching field. The combined interpretation of the experimental and theoretical data allows one to understand the effect of the magnetoelastic term on the value of the switching field, on one hand, and the effect of the magnetostatic term on the nucleation mechanism on the other, both with an essential impact on the characteristics of the nanowires’ magnetic bistability. The results are crucial for understanding the basic magnetic properties of these novel rapidly solidified ultrathin magnetic wires, as well as for tailoring their properties according to the specific requirements of various sensing applications. - Highlights: • Glass-coated nanowires have been very recently prepared by rapid solidification. • Amorphous wires change their properties as their diameter reaches the nano range. • Here we report on their main anisotropy terms: magnetoelastic and shape. • The results are essential for tailoring their properties for future applications.

Magnetic Bead—Magic Bullet

Directory of Open Access Journals (Sweden)

Christine Ruffert

2016-01-01

Full Text Available Microfluidics is assumed to be one of the leading and most promising areas of research since the early 1990s. In microfluidic systems, small spherical magnetic particles with superparamagnetic properties, called magnetic beads, play an important role in the design of innovative methods and tools, especially in bioanalysis and medical sciences. The intention of this review paper is to address main aspects from the state-of-the-art in the area of magnetic bead research, while demonstrating the broad variety of applications and the huge potential to solve fundamental biological and medical problems in the fields of diagnostics and therapy. Basic issues and demands related to the fabrication of magnetic particles and physical properties of nanosize magnets are discussed in Section 2. Of main interest are the control and adjustment of the nanoparticles’ properties and the availability of adequate approaches for particle detection via their magnetic field. Section 3 presents an overview of magnetic bead applications in nanomedicine. In Section 4, practical aspects of sample manipulation and separation employing magnetic beads are described. Finally, the benefits related to the use of magnetic bead-based microfluidic systems are summarized, illustrating ongoing questions and open tasks to be solved on the way to an approaching microfluidic age.

Time-resolved homo-FRET studies of biotin-streptavidin complexes.

Science.gov (United States)

Andreoni, Alessandra; Nardo, Luca; Rigler, Rudolf

2016-09-01

Förster resonance energy transfer is a mechanism of fluorescence quenching that is notably useful for characterizing properties of biomolecules and/or their interactions. Here we study water-solutions of Biotin-Streptavidin complexes, in which Biotin is labeled with a rigidly-bound fluorophore that can interact by Förster resonance energy transfer with the fluorophores labeling the other, up to three, Biotins of the same complex. The fluorophore, Atto550, is a Rhodamine analogue. We detect the time-resolved fluorescence decay of the fluorophores with an apparatus endowed with single-photon sensitivity and temporal resolution of ~30ps. The decay profiles we observe for samples containing constant Biotin-Atto550 conjugates and varying Streptavidin concentrations are multi-exponential. Each decay component can be associated with the rate of quenching exerted on each donor by each of the acceptors that label the other Biotin molecules, depending on the binding site they occupy. The main features that lead to this result are that (i) the transition dipole moments of the up-to-four Atto550 fluorophores that label the complexes are fixed as to both relative positions and mutual orientations; (ii) the fluorophores are identical and the role of donor in each Biotin-Streptavidin complex is randomly attributed to the one that has absorbed the excitation light (homo-FRET). Obviously the high-temporal resolution of the excitation-detection apparatus is necessary to discriminate among the fluorescence decay components. Copyright © 2016 Elsevier B.V. All rights reserved.

FDTD analysis of 3-D conducting target coated by anisotropic magnetized plasma

International Nuclear Information System (INIS)

Xu Lijun; Liu Shaobin; Mo Jinjun; Yuan Naichang

2006-01-01

The JEC finite-difference time-domain (JEC-FDTD) method is extended to three dimensional anisotropic dispersive media- the magnetized plasma. The problem which incorporates both anisotropy and frequency dispersion at the same time is solved for the electromagnetic wave propagation. The three dimensional JEC-FDTD formulations for anisotropic magnetized plasma are derived. The method is applied to the electromagnetic scattering of dihedral corner reflector and sphere-cone coated with anisotropic magnetized plasma. By simulating the interaction of electromagnetic wave with magnetized plasma, some numerical results are obtained, which indicate that an appropriate plasma coating may efficiently reduce the RCS of a metallic target. (authors)

Switchable cell trapping using superparamagnetic beads

Energy Technology Data Exchange (ETDEWEB)

Bryan, M. T.; Smith, K. H.; Real, M. E.; Bashir, M. A.; Fry, P. W.; Fischer, P.; Im, M.-Y.; Schrefl, T.; Allwood, D. A.; Haycock, J. W.

2010-04-30

Ni{sub 81}Fe{sub 19} microwires are investigated as the basis of a switchable template for positioning magnetically-labeled neural Schwann cells. Magnetic transmission X-ray microscopy and micromagnetic modeling show that magnetic domain walls can be created or removed in zigzagged structures by an applied magnetic field. Schwann cells containing superparamagnetic beads are trapped by the field emanating from the domain walls. The design allows Schwann cells to be organized on a surface to form a connected network and then released from the surface if required. As aligned Schwann cells can guide nerve regeneration, this technique is of value for developing glial-neuronal co-culture models in the future treatment of peripheral nerve injuries.

Magnetic properties of iron-based soft magnetic composites with SiO{sub 2} coating obtained by reverse microemulsion method

Energy Technology Data Exchange (ETDEWEB)

Wu, Shen [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Sun, Aizhi, E-mail: sunaizhi@126.com [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Lu, Zhenwen; Cheng, Chuan [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Gao, Xuexu [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

2015-05-01

In this work, iron-based soft magnetic composites coated with the amorphous SiO{sub 2} layer have been fabricated by utilizing tetraethoxysilane in the reverse microemulsion method, and then the effects of addition amount of SiO{sub 2} and annealing temperature on the magnetic properties were investigated. The results show that the surface of iron powders contains a thin amorphous SiO{sub 2} insulation layer, which effectively decreases the magnetic loss of synthesized magnets. The magnetic loss of coated samples decreased by 87.8% as compared with that of uncoated samples at 150 kHz. Magnetic measurements show that the sample with 1.25 wt% SiO{sub 2} has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Also, the annealing treatment increased the initial permeability, the maximum permeability and the magnetic induction and decreased the coercivity with increasing temperature in the range 300–600 °C. The results of the loss separation imply that the annealed SMCs have a higher hysteresis loss coefficient (k{sub 2}) and lower eddy current loss coefficient (k{sub 3}) as compared with the pure iron compacts after the same heat treatment due to the preservation of the SiO{sub 2} layer. - Highlights: • SiO{sub 2} coated the iron powder by reverse microemulsion method, decreased the magnetic loss of SMCs. • 25 wt% is the optimum coating amount to attain the desired permeability. • The influence of annealing temperature on the magnetic performance of the core was discussed. • Compare with the pure iron compacts, the annealed SMCs have lower value of eddy current coefficient.

Experiments, modeling and simulation of the magnetic behavior of inhomogeneously coated nickel/aluminum hybrid foams

Energy Technology Data Exchange (ETDEWEB)

Jung, A., E-mail: anne.jung@mx.uni-saarland.de [Universität des Saarlandes, Institute of Applied Mechanics, Campus A4 2, 66123 Saarbrücken (Germany); Klis, D., E-mail: d.klis@lte.uni-saarland.de [Universität des Saarlandes, Laboratory for Electromagnetic Theory, Campus C6 3, 66123 Saarbrücken (Germany); Goldschmidt, F., E-mail: f.goldschmidt@mx.uni-saarland.de [Universität des Saarlandes, Institute of Applied Mechanics, Campus A4 2, 66123 Saarbrücken (Germany)

2015-03-15

Open-cell metal foams are used as lightweight construction elements, energy absorbers or as support for catalytic coatings. Coating of open-cell metal foams is not only used for catalytic applications, but it leads also to tremendous increase in stiffness and energy absorption capacity. A non-line of sight coating technique for complex 3D structures is electrodeposition. Unfortunately, due to the 3D porosity and the related problems in mass transport limitation during the deposition, it is not possible to produce homogeneously coated foams. In the present contribution, we present a semi-non-destructive technique applicable to determine the coating thickness distribution of magnetic coatings by measuring the remanent magnetic field of coated foams. In order to have a closer look at the mass transport mechanism, a numerical model was developed to predict the field scans for different coating thickness distributions in the foams. For long deposition times the deposition reaches a steady state whereas a Helmholtz equation is sufficient to predict the coating thickness distribution. The applied current density could be identified as the main influencing parameter. Based on the developed model, it is possible to improve the electrodeposition process and hence the homogeneity in the coating thickness of coated metal foams. This leads to enhanced mechanical properties of the hybrid foams and contributes to better and resource-efficient energy absorbers and lightweight materials. - Highlights: • Production of hybrid foams by electrodeposition of nickel on open-cell metal foams. • Magnetic field scans for visualization of spatial coating thickness distribution. • Modeling of magnetic fields of inhomogeneously coated hybrid foams. • Investigation of mass transport limitation during coating by a Helmholtz equation. • Increasing coating homogeneity by use of low current densities and deposition rates.

Connecting DNA Origami Structures Using the Biotin-Streptavidin ...

African Journals Online (AJOL)

Abstract. This work made use of the strong interaction between biotin and streptavidin to connect designed DNA origami structures. The caDNAno software was used to design a 6 layer 3D origami cross-like structure. Selected DNA strands at the engineered attachment sites on the DNA origami structure were biotinylated.

Insulator coated magnetic nanoparticulate composites with reduced core loss and method of manufacture thereof

Science.gov (United States)

Zhang, Yide (Inventor); Wang, Shihe (Inventor); Xiao, Danny (Inventor)

2004-01-01

A series of bulk-size magnetic/insulating nanostructured composite soft magnetic materials with significantly reduced core loss and its manufacturing technology. This insulator coated magnetic nanostructured composite is comprises a magnetic constituent, which contains one or more magnetic components, and an insulating constituent. The magnetic constituent is nanometer scale particles (1-100 nm) coated by a thin-layered insulating phase (continuous phase). While the intergrain interaction between the immediate neighboring magnetic nanoparticles separated by the insulating phase (or coupled nanoparticles) provide the desired soft magnetic properties, the insulating material provides the much demanded high resistivity which significantly reduces the eddy current loss. The resulting material is a high performance magnetic nanostructured composite with reduced core loss.

Lab-on-a-Chip Magneto-Immunoassays: How to Ensure Contact between Superparamagnetic Beads and the Sensor Surface

Directory of Open Access Journals (Sweden)

Andreas Hütten

2013-09-01

Full Text Available Lab-on-a-chip immuno assays utilizing superparamagnetic beads as labels suffer from the fact that the majority of beads pass the sensing area without contacting the sensor surface. Different solutions, employing magnetic forces, ultrasonic standing waves, or hydrodynamic effects have been found over the past decades. The first category uses magnetic forces, created by on-chip conducting lines to attract beads towards the sensor surface. Modifications of the magnetic landscape allow for additional transport and separation of different bead species. The hydrodynamic approach uses changes in the channel geometry to enhance the capture volume. In acoustofluidics, ultrasonic standing waves force µm-sized particles onto a surface through radiation forces. As these approaches have their disadvantages, a new sensor concept that circumvents these problems is suggested. This concept is based on the granular giant magnetoresistance (GMR effect that can be found in gels containing magnetic nanoparticles. The proposed design could be realized in the shape of paper-based test strips printed with gel-based GMR sensors.

Bifunctional groups grafted polyethersulfone magnetic beads for selective sequestration of plutonium

International Nuclear Information System (INIS)

Paul, Sumana; Aggarwal, S.K.; Pandey, A.K.

2014-01-01

The present study involves synthesis of polyethersulfone (PES) beads grafted with two different monomers viz. 2-hydroxyethylmethacrylate phosphoric acid ester (HEMP) and 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) by photo-induced free radical polymerization method. The selection of bifunctional polymer was based on our previous studies, which indicated its efficacy for selective preconcentration of Pu from 3-4 mol L -1 HNO 3 . The HEMP-co-AMPS grafted PES beads were used for selective extraction of plutonium from dissolver solution

Superparamagnetic microbead transport induced by a magnetic field on large-area magnetic antidot arrays

Science.gov (United States)

Ouk, Minae; Beach, Geoffrey S. D.

2017-12-01

A method is presented for directed transport of superparamagnetic microbeads (SPBs) on magnetic antidot patterned substrates by applying a rotating elliptical magnetic field. We find a critical frequency for transport, beyond which the bead dynamics transitions from stepwise locomotion to local oscillation. We also find that the out-of-plane (HOOP) and in-plane (HIP) field magnitudes play crucial roles in triggering bead motion. Namely, we find threshold values in HOOP and HIP that depend on bead size, which can be used to independently and remotely address specific bead populations in a multi-bead mixture. These behaviors are explained in terms of the dynamic potential energy lansdscapes computed from micromagnetic simulations of the substrate magnetization configuration. Finally, we show that large-area magnetic patterns suitable for particle transport and sorting can be fabricated through a self-assembly lithography technique, which provides a simple, cost-effective means to integrate magnetic actuation into microfluidic systems.

One-Step Method for Preparation of Magnetic Nanoparticles Coated with Chitosan

Directory of Open Access Journals (Sweden)

Karla M. Gregorio-Jauregui

2012-01-01

Full Text Available Preparation of magnetic nanoparticles coated with chitosan in one step by the coprecipitation method in the presence of different chitosan concentrations is reported here. Obtaining of magnetic superparamagnetic nanoparticles was confirmed by X-ray diffraction and magnetic measurements. Scanning transmission electron microscopy allowed to identify spheroidal nanoparticles with around 10-11 nm in average diameter. Characterization of the products by Fourier transform infrared spectroscopy demonstrated that composite chitosan-magnetic nanoparticles were obtained. Chitosan content in obtained nanocomposites was estimated by thermogravimetric analysis. The nanocomposites were tested in Pb2+ removal from a PbCl2 aqueous solution, showing a removal efficacy up to 53.6%. This work provides a simple method for chitosan-coated nanoparticles obtaining, which could be useful for heavy metal ions removal from water.

Enhanced quality factors and force sensitivity by attaching magnetic beads to cantilevers for atomic force microscopy in liquid

Science.gov (United States)

Hoof, Sebastian; Nand Gosvami, Nitya; Hoogenboom, Bart W.

2012-12-01

Dynamic-mode atomic force microscopy (AFM) in liquid remains complicated due to the strong viscous damping of the cantilever resonance. Here, we show that a high-quality resonance (Q >20) can be achieved in aqueous solution by attaching a microgram-bead at the end of the nanogram-cantilever. The resulting increase in cantilever mass causes the resonance frequency to drop significantly. However, the force sensitivity—as expressed via the minimum detectable force gradient—is hardly affected, because of the enhanced quality factor. Through the enhancement of the quality factor, the attached bead also reduces the relative importance of noise in the deflection detector. It can thus yield an improved signal-to-noise ratio when this detector noise is significant. We describe and analyze these effects for a set-up that includes magnetic actuation of the cantilevers and that can be easily implemented in any AFM system that is compatible with an inverted optical microscope.

Magnetic Nanoparticles Coated with a Thermosensitive Polymer with Hyperthermia Properties

Directory of Open Access Journals (Sweden)

Felisa Reyes-Ortega

2017-12-01

Full Text Available Magnetic nanoparticles (MNPs have been widely used to increase the efficacy of chemotherapeutics, largely through passive accumulation provided by the enhanced permeability and retention effect. Their incorporation into biopolymer coatings enables the preparation of magnetic field-responsive, biocompatible nanoparticles that are well dispersed in aqueous media. Here we describe a synthetic route to prepare functionalized, stable magnetite nanoparticles (MNPs coated with a temperature-responsive polymer, by means of the hydrothermal method combined with an oil/water (o/w emulsion process. The effects of both pH and temperature on the electrophoretic mobility and surface charge of these MNPs are investigated. The magnetite/polymer composition of these systems is detected by Fourier Transform Infrared Spectroscopy (FTIR and quantified by thermogravimetric analysis. The therapeutic possibilities of the designed nanostructures as effective heating agents for magnetic hyperthermia are demonstrated, and specific absorption rates as high as 150 W/g, with 20 mT magnetic field and 205 kHz frequency, are obtained. This magnetic heating response could provide a promising nanoparticle system for combined diagnostics and cancer therapy.

Hybrid, silica-coated, Janus-like plasmonic-magnetic nanoparticles

OpenAIRE

Sotiriou, Georgios A.; Hirt, Ann M.; Lozach, Pierre-Yves; Teleki, Alexandra; Krumeich, Frank; Pratsinis, Sotiris E.

2011-01-01

Hybrid plasmonic-magnetic nanoparticles possess properties that are attractive in bioimaging, targeted drug delivery, in vivo diagnosis and therapy. The stability and toxicity, however, of such nanoparticles challenge their safe use today. Here, biocompatible, SiO2-coated, Janus-like Ag/Fe2O3 nanoparticles are prepared by one-step, scalable flame aerosol technology. A nanothin SiO2 shell around these multifunctional nanoparticles leaves intact their morphology, magnetic and plasmonic properti...

Certain patterns of IgG adsorption by polystyrene bead surfaces

Energy Technology Data Exchange (ETDEWEB)

Mamedov, M K

1985-01-01

The article reports on tests of domestic Soviet polystyrene beads that permit a simplified modification of the enzyme-adsorption method to identify the alpha hepatitis virus and its antibody in nonspecialized, general laboratories. Only patterns of Ig immunoglobulin adsorption were studied. Human IgG was conjugated with the radioactive isotope /sup 125/I by a chloramine method, with mean radioactivity and protein concentration measured frequently. Bovine serum albumin (BSA) and an anionic detergent Tween-20, and a phosphate-salt buffer with pH 5.8-8.2, were used to produce m-Ig and Ig. Adsorption involved incubation of the beads in various solutions, followed by measurement of their radioactivity. Results of several series of tests were subjected to Student-Fisher evaluation. This suggested that the presence of albumin in physiological concentrations in the solution had no important impact on m-Ig adsorption on the bead surface, which effectively adsorbed Ig from solutions without additional proteins, but also from Ig solutions containing serum albumin in physiological concentrations. Thus, it was possible to coat the beads with alpha Ig hepatitis virus. The Tween-20 weak detergent was effective for eliminating unwanted protein adsorption. 9 references, 3 figures.

Alignment of SWNTs by protein-ligand interaction of functionalized magnetic particles under low magnetic fields.

Science.gov (United States)

Park, Tae Jung; Park, Jong Pil; Lee, Seok Jae; Jung, Dae-Hwan; Ko, Young Koan; Jung, Hee-Tae; Lee, Sang Yup

2011-05-01

Carbon nanotubes (CNTs) have attracted considerable attention for applications using their superior mechanical, thermal and electrical properties. A simple method to controllably align single-walled CNTs (SWNTs) by using magnetic particles embedded with superparamagnetic iron oxide as an accelerator under the magnetic field was developed. The functionalization of SWNTs using biotin, interacted with streptavidin-coupled magnetic particles (micro-to-nano in diameter), and layer-by-layer assembly were performed for the alignment of a particular direction onto the clean silicon and the gold substrate at very low magnetic forces (0.02-0.89 T) at room temperature. The successful alignment of the SWNTs with multi-layer film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By changing the orientation and location of the substrates, crossed-networks of SWNTs-magnetic particle complex could easily be fabricated. We suggest that this approach, which consists of a combination of biological interaction among streptavidin-biotin and magnetite particles, should be useful for lateral orientation of individual SWNTs with controllable direction.

Sequential mass spectrometric analysis of uranium and plutonium employing resin bead technique

International Nuclear Information System (INIS)

Ramakumar, K.L.; Aggarwal, S.K.; Chitambar, S.A.; Jain, H.C.

1985-01-01

Sequential mass spectrometric analysis of uranium and plutonium employing anion exchange resin bead technique is reported using a high sensitive single stage magnetic analyser instrument, the routinely employed rhenium double filament assembly and 0.5M HNO 3 as a wetting agent for loading the resin beads. A precision of bettter than 0.3per cent (2sigma) is obtained on the isotopic ratio measurements. However, extreme care has to be exercised to carry the resin bead experiments under ultra clean conditions so as to avoid pick up of contamination. (author)

Detection of smaller Jc region and damage in YBCO coated conductors by using permanent magnet method

International Nuclear Information System (INIS)

Hattori, K.; Saito, A.; Takano, Y.; Suzuki, T.; Yamada, H.; Takayama, T.; Kamitani, A.; Ohshima, S.

2011-01-01

We developed a non-destructive method for measuring the critical current density (J c ) in YBCO-coated conductors by using a permanent magnet (Sm 2 Co 17 ). J c could be determined from the repulsive force (F r ) generated between a permanent magnet and a coated conductor where shielding current flows. We also examined the influence of damage to the film on the J c distribution. The measured F r when the permanent magnet approached the cut part was smaller than that of the undamaged area. We developed a non-destructive method for measuring the critical current density (J c ) in YBCO-coated conductors by using a permanent magnet (Sm 2 Co 17 ). J c could be determined from the repulsive force (F r ) generated between a permanent magnet and a coated conductor where shielding current flows. We tried to detect a smaller J c region in the coated conductor by using the system. The J c distribution could be determined without influence from the thick copper film on YBCO thin film. We also examined the influence of damage to the film on the J c distribution. The surface of the coated conductors was cut by using a knife. The measured F r when the permanent magnet approached the cut part was smaller than that of the undamaged area. This J c measurement technique will be useful for detecting smaller J c regions and defects in coated conductors.

A magnetic method to concentrate and trap biological targets

KAUST Repository

Li, Fuquan

2012-11-01

Magnetoresistive sensors in combination with magnetic particles have been used in biological applications due to, e.g., their small size and high sensitivity. A growing interest is to integrate magnetoresistive sensors with microchannels and electronics to fabricate devices that can perform complex analyses. A major task in such systems is to immobilize magnetic particles on top of the sensor surface, which is required to detect the particles\\' stray field. In the presented work, a bead concentrator, consisting of gold microstructures, at the bottom of a microchannel, is used to attract and move magnetic particles into a trap. The trap is made of a chamber with a gold microstructure underneath and is used to attract and immobilize a defined number of magnetic beads. In order to detect targets, two kinds of solutions were prepared; one containing only superparamagnetic particles, the other one containing beads with the protein Bovine serum albumin as the target and fluorescent markers. Due to the size difference between bare beads and beads with target, less magnetic beads were immobilized inside the volume chamber in case of magnetic beads with target as compared to bare magnetic beads. © 1965-2012 IEEE.

Effect of administration route and dose of streptavidin or biotin on the tumor uptake of radioactivity in intraperitoneal tumor with multistep targeting

International Nuclear Information System (INIS)

Zhang Meili; Yao Zhengsheng; Sakahara, Harumi; Saga, Tsuneo; Nakamoto, Yuji; Sato, Noriko; Zhao Songji; Nakada, Hiroshi; Yamashina, Ikuo; Konishi, Junji

1998-01-01

The effect of the administration route and dose of streptavidin or biotin on the biodistribution of radioactivity in multistep targeting was studied in nude mice bearing intraperitoneal (IP) colon cancer xenograft. The multistep targeting included a two-step method using biotinylated antibody and radiolabeled streptavidin and a three-step method with radiolabeled biotin based on the two-step method. A monoclonal antibody, MLS128, which recognizes Tn antigen on mucin, was biotinylated and injected intravenously (IV) or IP in nude mice bearing human colon cancer LS180 IP xenografts for pretargeting. In the two-step method, IP-injected streptavidin showed a higher tumor uptake and tumor-to-nontumor ratios than IV-injected streptavidin regardless of administration route of pretargeting. The tumor uptake of radiolabeled streptavidin was increased with a high dose of biotinylated antibody pretargeting, but decreased with an increasing dose of streptavidin. In the three-step targeting, IP injection also gave a higher tumor uptake of radiolabeled biotin than IV injection. In conclusion, IP administration of radiolabeled streptavidin or biotin resulted in more efficient IP tumor targeting with the multistep methods

Fluorescent detection of C-reactive protein using polyamide beads

Science.gov (United States)

Jagadeesh, Shreesha; Chen, Lu; Aitchison, Stewart

2016-03-01

Bacterial infection causes Sepsis which is one of the leading cause of mortality in hospitals. This infection can be quantified from blood plasma using C - reactive protein (CRP). A quick diagnosis at the patient's location through Point-of- Care (POC) testing could give doctors the confidence to prescribe antibiotics. In this paper, the development and testing of a bead-based procedure for CRP quantification is described. The size of the beads enable them to be trapped in wells without the need for magnetic methods of immobilization. Large (1.5 mm diameter) Polyamide nylon beads were used as the substrate for capturing CRP from pure analyte samples. The beads captured CRP either directly through adsorption or indirectly by having specific capture antibodies on their surface. Both methods used fluorescent imaging techniques to quantify the protein. The amount of CRP needed to give a sufficient fluorescent signal through direct capture method was found suitable for identifying bacterial causes of infection. Similarly, viral infections could be quantified by the more sensitive indirect capture method. This bead-based assay can be potentially integrated as a disposable cartridge in a POC device due to its passive nature and the small quantities needed.

Microfluidic magnetic separator using an array of soft magnetic elements

DEFF Research Database (Denmark)

Smistrup, Kristian; Lund-Olesen, Torsten; Hansen, Mikkel Fougt

2006-01-01

We present the design, fabrication, characterization, and demonstration of a new passive magnetic bead separator. The device operates in an effective state when magnetized by an external magnetic field of only 50 mT, which is available from a tabletop electromagnet. We demonstrate the complete...... capture of 1.0 mu m fluorescent magnetic beads from a 7.5 mu L sample volume traveling at an average linear fluid velocity of 5 mm/s....

Magnetically anisotropic additive for scalable manufacturing of polymer nanocomposite: iron-coated carbon nanotubes

International Nuclear Information System (INIS)

Yamamoto, Namiko; Manohara, Harish; Platzman, Ellen

2016-01-01

Novel nanoparticles additives for polymer nanocomposites were prepared by coating carbon nanotubes (CNTs) with ferromagnetic iron (Fe) layers, so that their micro-structures can be bulk-controlled by external magnetic field application. Application of magnetic fields is a promising, scalable method to deliver bulk amount of nanocomposites while maintaining organized nanoparticle assembly throughout the uncured polymer matrix. In this work, Fe layers (∼18 nm thick) were deposited on CNTs (∼38 nm diameter and ∼50 μm length) to form thin films with high aspect ratio, resulting in a dominance of shape anisotropy and thus high coercivity of ∼50–100 Oe. The Fe-coated CNTs were suspended in water and applied with a weak magnetic field of ∼75 G, and yet preliminary magnetic assembly was confirmed. Our results demonstrate that the fabricated Fe-coated CNTs are magnetically anisotropic and effectively respond to magnetic fields that are ∼10 3 times smaller than other existing work (∼10 5 G). We anticipate this work will pave the way for effective property enhancement and bulk application of CNT–polymer nanocomposites, through controlled micro-structure and scalable manufacturing. (paper)

The role of CH/π interactions in the high affinity binding of streptavidin and biotin.

Science.gov (United States)

Ozawa, Motoyasu; Ozawa, Tomonaga; Nishio, Motohiro; Ueda, Kazuyoshi

2017-08-01

The streptavidin-biotin complex has an extraordinarily high affinity (Ka: 10 15 mol -1 ) and contains one of the strongest non-covalent interactions known. This strong interaction is widely used in biological tools, including for affinity tags, detection, and immobilization of proteins. Although hydrogen bond networks and hydrophobic interactions have been proposed to explain this high affinity, the reasons for it remain poorly understood. Inspired by the deceased affinity of biotin observed for point mutations of streptavidin at tryptophan residues, we hypothesized that a CH/π interaction may also contribute to the strong interaction between streptavidin and biotin. CH/π interactions were explored and analyzed at the biotin-binding site and at the interface of the subunits by the fragment molecular orbital method (FMO) and extended applications: PIEDA and FMO4. The results show that CH/π interactions are involved in the high affinity for biotin at the binding site of streptavidin. We further suggest that the involvement of CH/π interactions at the subunit interfaces and an extended CH/π network play more critical roles in determining the high affinity, rather than involvement at the binding site. Copyright © 2017 Elsevier Inc. All rights reserved.

Design study of superconducting sextupole magnet using HTS coated conductor for neutron-focusing device

International Nuclear Information System (INIS)

Tosaka, T.; Koyanagi, K.; Ono, M.; Kuriyama, T.; Watanabe, I.; Tsuchiya, K.; Suzuki, J.; Adachi, T.; Shimizu, H.M.

2006-01-01

We performed a design study of sextupole magnet using high temperature superconducting (HTS) wires. The sextupole magnet is used as a focusing lens for neutron-focusing devices. A neutron-focusing device is desired to have a large aperture and a high magnetic field gradient of G, where G = 2B/r 2 , B is the magnetic field and r is a distance from the sextupole magnet axis. Superconducting magnets offer promising prospects to meet the demands of a neutron-focusing device. Recently NbTi coils of low temperature superconducting (LTS) have been developed for a sextupole magnet with a 46.8 mm aperture. The maximum magnetic field gradient G of this magnet is 9480 T/m 2 at 4.2 K and 12,800 T/m 2 at 1.8 K. On the other hand, rapid progress on second generation HTS wire has been made in increasing the performance of critical current and in demonstrating a long length. The second generation HTS wire is referred to as coated conductor. It consists of tape-shaped base upon which a thin coating of superconductor, usually YBCO, is deposited or grown. This paper describes a design study of sextupole magnet using coated conductors

A giant magnetoresistance ring-sensor based microsystem for magnetic bead manipulation and detection

KAUST Repository

Gooneratne, Chinthaka P.

2011-03-28

In this paper a novel spin valvegiant magnetoresistance(GMR) ring-sensor integrated with a microstructure is proposed for concentrating, trapping, and detecting superparamagnetic beads (SPBs). Taking advantage of the fact that SPBs can be manipulated by an external magnetic field, a unique arrangement of conducting microrings is utilized to manipulate the SPBs toward the GMR sensing area in order to increase the reliability of detection. The microrings are arranged and activated in such a manner so as to enable the detection of minute concentrations of SPBs in a sample. Precise manipulation is achieved by applying current sequentially to the microrings. The fabricated ring-shaped GMR element is located underneath the innermost ring and has a magnetoresistance of approximately 5.9%. By the performed experiments it was shown that SPBs could be successfully manipulated toward the GMR sensing zone.

A giant magnetoresistance ring-sensor based microsystem for magnetic bead manipulation and detection

KAUST Repository

Gooneratne, Chinthaka P.; Giouroudi, Ioanna; Liang, Cai; Kosel, Jü rgen

2011-01-01

In this paper a novel spin valvegiant magnetoresistance(GMR) ring-sensor integrated with a microstructure is proposed for concentrating, trapping, and detecting superparamagnetic beads (SPBs). Taking advantage of the fact that SPBs can be manipulated by an external magnetic field, a unique arrangement of conducting microrings is utilized to manipulate the SPBs toward the GMR sensing area in order to increase the reliability of detection. The microrings are arranged and activated in such a manner so as to enable the detection of minute concentrations of SPBs in a sample. Precise manipulation is achieved by applying current sequentially to the microrings. The fabricated ring-shaped GMR element is located underneath the innermost ring and has a magnetoresistance of approximately 5.9%. By the performed experiments it was shown that SPBs could be successfully manipulated toward the GMR sensing zone.

Se-SAD serial femtosecond crystallography datasets from selenobiotinyl-streptavidin

Science.gov (United States)

Yoon, Chun Hong; Demirci, Hasan; Sierra, Raymond G.; Dao, E. Han; Ahmadi, Radman; Aksit, Fulya; Aquila, Andrew L.; Batyuk, Alexander; Ciftci, Halilibrahim; Guillet, Serge; Hayes, Matt J.; Hayes, Brandon; Lane, Thomas J.; Liang, Meng; Lundström, Ulf; Koglin, Jason E.; Mgbam, Paul; Rao, Yashas; Rendahl, Theodore; Rodriguez, Evan; Zhang, Lindsey; Wakatsuki, Soichi; Boutet, Sébastien; Holton, James M.; Hunter, Mark S.

2017-04-01

We provide a detailed description of selenobiotinyl-streptavidin (Se-B SA) co-crystal datasets recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) for selenium single-wavelength anomalous diffraction (Se-SAD) structure determination. Se-B SA was chosen as the model system for its high affinity between biotin and streptavidin where the sulfur atom in the biotin molecule (C10H16N2O3S) is substituted with selenium. The dataset was collected at three different transmissions (100, 50, and 10%) using a serial sample chamber setup which allows for two sample chambers, a front chamber and a back chamber, to operate simultaneously. Diffraction patterns from Se-B SA were recorded to a resolution of 1.9 Å. The dataset is publicly available through the Coherent X-ray Imaging Data Bank (CXIDB) and also on LCLS compute nodes as a resource for research and algorithm development.

Early Diagnosis of Irkut Virus Infection Using Magnetic Bead-Based Serum Peptide Profiling by MALDI-TOF MS in a Mouse Model

Directory of Open Access Journals (Sweden)

Nan Li

2014-03-01

Full Text Available Early diagnosis is important for the prompt post-exposure prophylaxis of lyssavirus infections. To diagnose Irkut virus (IRKV infection during incubation in mice, a novel method using magnetic bead-based serum peptide profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS has been established. For this test, serum peptides were concentrated by adsorption to and elution from the magnetic bead-based weak cation ion exchanger. Mass spectrograms obtained by MALDI-TOF MS were analyzed using ClinProTools bioinformatics software. Construction of the diagnostic model was performed using serum samples from mice infected with IRKV and rabies virus (RABV BD06, Flury-LEP, and SRV9 (as controls. The method accurately diagnosed sera 2, 4 and 8 days after IRKV and RABV infections. The sensitivity, specificity, and total accuracy of diagnosis were 86.7%, 95.2%, and 92.9%, respectively. However, IRKV could not be differentiated from RABV 1 day after infection. The results of the present study indicate that serum peptide profiling by MALDI-TOF MS is a promising technique for the early clinical diagnosis of lyssavirus infections and needs to be further tested in humans and farm animals.

Targeting of [[sup 111]In]biocytin to cultured ovarian adenocarcinoma cells using covalent monoclonal antibody -streptavidin conjugates

Energy Technology Data Exchange (ETDEWEB)

Sheldon, K.; Marks, A. (Toronto Univ., ON (Canada). Banting and Best Dept. of Medical Research); Baumal, R. (Hospital for Sick Children, Toronto, ON (Canada). Dept. of Pathology)

1992-11-01

Three monoclonal antibodies (mAb) directed against the human ovarian adenocarcinoma cell line HEY, were substituted with maleimide and covalently bonded to thiolated streptavidin. The conjugates were separated from unreacted reagents by successive affinity chromatography on protein A-Sepharose and iminobiotin columns. Purified conjugates consisted of an immunoglobulin (Ig) monomer bound to a streptavidin tetramer through a covalent bond between the Ig molecule and one of the streptavidin subunits. The conjugates were able to specifically target [[sup 111]In]biocytin to HEY cells in vitro in the presence of human serum and ascitic fluid from ovarian cancer patients. (Author).

Estimation of magnetic relaxation property for CVD processed YBCO-coated conductors

International Nuclear Information System (INIS)

Takahashi, Y.; Kiuchi, M.; Otabe, E.S.; Matsushita, T.; Shikimachi, K.; Watanabe, T.; Kashima, N.; Nagaya, S.

2010-01-01

Ion Beam Assist Deposition/Chemical Vapor Deposition(IBAD/CVD)-processed YBCO-coated conductors with high critical current density J c at high magnetic fields are expected to be applied to superconducting equipments such as superconducting magnetic energy storage (SMES). For application to superconducting magnet in SMES one of the most important properties for superconductors is the relaxation property of superconducting current. In this paper, the relaxation property is investigated for IBAD/CVD-processed YBCO-coated conductors of the superconducting layer in the range of 0.18-0.90 μm. This property can be quantitatively characterized by the apparent pinning potential, U 0 *. It is found that U 0 * takes a smaller value due to the two-dimensional pinning mechanism at high magnetic fields for conductor with thinner superconducting layer. Although U 0 * decreases with increasing thickness at low magnetic fields at 20 K, it increases at high magnetic fields. The results are theoretically explained by the model of the flux creep and flow based on the dimensionality of flux pinning. Scaling analysis is examined for the dependence of U 0 * on the magnetic field, temperature and the layer thickness.

Effect of surfactant coating on magnetic properties of Fe3O4 nanoparticles: ESR study

International Nuclear Information System (INIS)

Koeseoglu, Yueksel

2006-01-01

Magnetic properties of surfactant-coated and uncoated superparamagnetic iron oxide nanoparticles, Fe 3 O 4 (SPION) were investigated by electron spin resonance (ESR) technique. For all samples, a strong and broad single ESR signal has been observed at all temperatures. A strong temperature dependence of ESR linewidth and resonance field is observed. Also, there is a strong effect of surfactant coating on magnetic properties of Fe 3 O 4 nanoparticles. While the resonance field is decreasing by coating, the linewidth of the ESR spectra is increasing. These changes in resonance field and the linewidth are attributed to the decrease in effective magnetic moment due to a non-collinear spin structure originated from the pinning of the surface spins and coated surfactant at the interface of nanoparticles. Also, the changes are due to the contribution of the volume of the diamagnetic coating mass to the sample volume

Magnetic nanoparticles coated with polyaniline to stabilize immobilized trypsin

Energy Technology Data Exchange (ETDEWEB)

Maciel, J. C., E-mail: jackeline-maciel@hotmail.com [Universidade Federal de Roraima (Brazil); Mercês, A. A. D.; Cabrera, M. [Universidade Federal de Pernambuco, Laboratório de Imunopatologia Keizo Asami (Brazil); Shigeyosi, W. T. [Universidade Federal de São Carlos, Departamento de Física (Brazil); Souza, S. D. de; Olzon-Dionysio, M.; Fabris, J. D. [Universidade Federal dos Vales de Jequitinhonha e Mucuri (Brazil); Cardoso, C. A. [Universidade Federal de São Carlos, Departamento de Física (Brazil); Neri, D. F. M. [Universidade Federal do Vale do São Francisco (Brazil); Silva, M. P. C.; Carvalho, L. B. [Universidade Federal de Pernambuco, Laboratório de Imunopatologia Keizo Asami (Brazil)

2016-12-15

It is reported the synthesis of magnetic nanoparticles via the chemical co-precipitation of Fe {sup 3+} ions and their preparation by coating them with polyaniline. The electronic micrograph analysis showed that the mean diameter for the nanoparticles is ∼15 nm. FTIR, powder X-ray diffraction and Mössbauer spectroscopy were used to understand the chemical, crystallographic and {sup 57}Fe hyperfine structures for the two samples. The nanoparticles, which exhibited magnetic behavior with relatively high spontaneous magnetization at room temperature, were identified as being mainly formed by maghemite (γFe{sub 2}O{sub 3}). The coated magnetic nanoparticles (sample labeled “mPANI”) presented a real ability to bind biological molecules such as trypsin, forming the magnetic enzyme derivative (sample “mPANIG-Trypsin”). The amount of protein and specific activity of the immobilized trypsin were found to be 13±5 μg of protein/mg of mPANI (49.3 % of immobilized protein) and 24.1±0.7 U/mg of immobilized protein, respectively. After 48 days of storage at 4 {sup ∘}C, the activity of the immobilized trypsin was found to be 89 % of its initial activity. This simple, fast and low-cost procedure was revealed to be a promising way to prepare mPANI nanoparticles if technological applications addressed to covalently link biomolecules are envisaged. This route yields chemically stable derivatives, which can be easily recovered from the reaction mixture with a magnetic field and recyclable reused.

A Mössbauer study of the chemical stability of iron oxide nanoparticles in PMMA and PVB beads

DEFF Research Database (Denmark)

Chen, Wei; Mørup, Steen; Hansen, Mikkel Fougt

2008-01-01

We have prepared magnetic beads consisting of iron oxide nanoparticles in a polymethyl methacrylate (PMMA) and a polyvinyl butyral (PVB) matrix. High-field Mossbauer studies show that the particles have an almost perfect collinear spin structure and magnetization measurements show that they are s...... transformed to maghemite. The PVB beads are hydrophilic and biocompatible and are therefore well suited for applications in medicine and biology....

Experiment list: SRX319558 [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available | cell type=mouse embryonic stem cells || genotype/variation=expressing control BirA || chip beads=Dynabeads... MyOne Streptavidin T1 || chip beads vendor=Invitrogen http://dbarchive.bioscienc

Experiment list: SRX319557 [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available se embryonic stem cells || genotype/variation=expressing Flag-bio tagged Nanog || chip beads=Dynabeads MyOne... Streptavidin T1 || chip beads vendor=Invitrogen http://dbarchive.biosciencedbc.j

Experiment list: SRX172567 [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available P-Seq source_name=Embryonic Stem Cell || background mouse strain=129SvJae/C57BL/6 || chip antibody=streptavidin beads... || antibody vendor/catalog=Invitrogen 656-01 Dynabeads® MyOne? Streptavidin T1 || genotype/variati

ANOMALOUS ELECTRODEPOSITION OF Fe-Ni ALLOY COATING FROM SIMPLE AND COMPLEX BATHS AND ITS MAGNETIC PROPERTY

Directory of Open Access Journals (Sweden)

M A Islam

2010-03-01

Full Text Available Electrodeposition of Fe-Ni thin films has been carried on copper substrate under various electrodeposition conditions from two simple and six complex baths. Sulfate baths composing of NiSO4. 7H2O, FeSO4.7H2O, H3BO3 and Na2SO4KEYWORDS: Anomalous Electrodeposition, Fe-Ni Coating, Complexing agent, Current Density, Magnetic Property. 1. INTRODUCTION Alloy electrodeposition technologies can extend tremendously the potential of electrochemical deposition processes to provide coatings that require unique mechanical, chemical and physical properties [1]. There has been a great research interest in the development and characterization of iron-nickel (Fe-Ni thin films due to their operational capacity, economic interest, magnetic and other properties [2]. Due to their unique low coefficient of thermal expansion (CTE and soft magnetic properties, Fe-Ni alloys have been used in industrial applications for over 100 years [3]. Typical examples of applications that are based on the low CTE of Fe-Ni alloys include: thermostatic bimetals, glass sealing, integrated circuit packaging, cathode ray tube, shadow masks, membranes for liquid natural gas tankers; applications based on the soft magnetic properties include: read-write heads for magnetic storage, magnetic actuators, magnetic shielding, high performance transformer cores. comprise the simple baths whereas complex baths were prepared by adding ascorbic acid, saccharin and citric acid in simple baths. The effect of bath composition, pH and applied current density on coating appearance, composition, morphology and magnetic property were studied. Wet chemical analysis technique was used to analyze the coating composition whereas SEM and VSM were used to study the deposit morphology and magnetic property respectively. Addition of complexing agents in plating baths suppressed the anomalous nature of Fe-Ni alloy electrodeposition. Coatings obtained from simple baths were characterized by coarse grained non

Magnetic heating by silica-coated Co–Zn ferrite particles

Czech Academy of Sciences Publication Activity Database

Veverka, Miroslav; Závěta, K.; Kaman, Ondřej; Veverka, Pavel; Knížek, Karel; Pollert, Emil; Burian, M.; Kašpar, P.

2014-01-01

Roč. 47, č. 6 (2014), "065503-1"-"065503-11" ISSN 0022-3727 R&D Projects: GA ČR GAP204/10/0035; GA ČR(CZ) GAP108/11/0807 Institutional support: RVO:68378271 Keywords : cobalt–zinc ferrite * magnetic nanoparticles * coprecipitation * silica coating * hysteresis loops * calorimetric measurements * hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.721, year: 2014 http://stacks.iop.org/0022-3727/47/065503

Development of simple immunoradiometric assays using avidin coupled to polystyrene beads as a common solid phase

International Nuclear Information System (INIS)

Jyotsna, N.; Singh, Y.; Chouthkanthiwar, V.; Paradkar, S.; Sivaprasad, N.

1998-01-01

In this paper, we describe the preparation and application of avidin coupled polystyrene beads as a common solid phase for use in immunoradiometric assays (IRMAs). The assay system is based on two matched commercial monoclonal antibodies, of which, the capture antibody is biotinylated using biotinamidocaproate N-hydroxysuccinimide ester and the detection antibody is radiolabeled with 125 I by conventional Chloramine-T method. Avidin was immobilized on the polystyrene beads through a primary coat of bovine serum albumin using glutaraldhyde activation method. Various factors, such as concentration of reagents, incubation time, etc. were optimised to obtain a simple assay protocol consisting of only two pipetting steps, namely, that of a mixture of the two labelled antibodies (radiolabelled and biotinylated) and of the standard or sample. The advantage of the Avidin-Biotin system is the improved sensitivity, economy of antibody and the possibility to use a common solid phase in assays for different analytes. Using the polystyrene beads along with the novel decanting device, it has been possible to achieve the convenience of the 'coated-tube' technology without the expensive automation necessary for large scale preparation of antibody coated tubes. This protocol has been successfully applied to Prolactin, LH and FSH assays. The sensitivity of the Prolactin assay is 8μIU/mL (0.3 ng/mL), that of the FSH assay is 1mIU/mL and that of the LH assay is 0.9 mIU/mL. The intra-assay and inter-assay variations were <10%. Shelf life of the avidin coupled beads was found to be about 8 months and that of the biotin labelled antibodies up to 18 months. (author)

Progammed synthesis of magnetic mesoporous silica coated carbon nanotubes for organic pollutant adsorption

Energy Technology Data Exchange (ETDEWEB)

Tong, Yue; Zhang, Min, E-mail: congmingyang123@163.com; Xia, Peixiong; Wang, Linlin; Zheng, Jing; Li, Weizhen; Xu, Jingli, E-mail: xujingli@sues.edu.cn

2016-05-15

Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis method and were characterized by TEM, XRD, FTIR, TGA, N{sub 2} adsorption–desorption and VSM. The well-designed mesoporous magnetic nanotubes had a large specific area, a highly open mesoporous structure and high magnetization. Firstly, SiO{sub 2}-coated maghemite/CNTs nanoparticles (CNTs/Fe{sub 3}O{sub 4}@SiO{sub 2} composites) were synthesized by the combination of high temperature decomposition process and an sol–gel method, in which the iron acetylacetonate as well as TEOS acted as the precursor for maghemite and SiO{sub 2}, respectively. The CNTs/Fe{sub 3}O{sub 4}@SiO{sub 2} composites revealed a core–shell structure, Then, CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} was obtained by extracting cetyltrimethylammonium bromide (CTAB) via an ion-exchange procedure. The resulting composites show not only a magnetic response to an externally applied magnetic field, but also can be a good adsorbent for the organic pollutant in the ambient temperature. - Graphical abstract: Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis, which can be a good adsorbent for the organic pollutant in the ambient temperature. - Highlights: • The surface of CNTs/Fe{sub 3}O{sub 4} is hydrophilic, which facilitates the silica coating. • The CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} was synthesized by a facile method. • The CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} can be a good adsorbent for the organic pollutant.

Iron-based soft magnetic composites with Mn–Zn ferrite nanoparticles coating obtained by sol–gel method

International Nuclear Information System (INIS)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-01-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn–Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol–gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn–Zn ferrites. Mn–Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn–Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn–Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability. - Highlights: ► Uniformly coated Mn–Zn ferrite powder increased the operating frequency of SMCs. ► Compared with epoxy coated, the permeability of SMCs increased by 33.5% at 10 kHz. ► 400 °C is the optimum annealing temperature to attain the desired permeability.

Iron-based soft magnetic composites with Mn-Zn ferrite nanoparticles coating obtained by sol-gel method

Science.gov (United States)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-11-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn-Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol-gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn-Zn ferrites. Mn-Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn-Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn-Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

Novel multi-biotin grafted poly(lactic acid) and its self-assembling nanoparticles capable of binding to streptavidin

Science.gov (United States)

Yan, Hao; Jiang, Weimin; Zhang, Yinxing; Liu, Ying; Wang, Bin; Yang, Li; Deng, Lihong; Singh, Gurinder K; Pan, Jun

2012-01-01

Targeted drug delivery requires novel biodegradable, specific binding systems with longer circulation time. The aim of this study was to prepare biotinylated poly(lactic acid) (PLA) nanoparticles (NPs) which can meet regular requirements as well conjugate more biotins in the polymer to provide better binding with streptavidin. A biotin-graft-PLA was synthesized based on previously published biodegradable poly(ethylene glycol) (PEG)-graft-PLA, with one polymer molecule containing three PEG molecules. Newly synthesized biotin-graft-PLA had three biotins per polymer molecule, higher than the previous biotinylated PLA (≤1 biotin per polymer molecule). A PEG with a much lower molecular weight (MW ~1900) than the previous biotinylated PLA (PEG MW ≥ 3800), and thus more biocompatible, was used which supplied good nonspecific protein-resistant property compatible to PEG-graft-PLA, suggesting its possible longer stay in the bloodstream. Biotin-graft-PLA specifically bound to streptavidin and self-assembled into NPs, during which naproxen, a model small molecule (MW 230 Da) and hydrophobic drug, was encapsulated (encapsulation efficiency 51.88%). The naproxen-loaded NPs with particle size and zeta potential of 175 nm and −27.35 mV realized controlled release within 170 hours, comparable to previous studies. The biotin-graft-PLA NPs adhered approximately two-fold more on streptavidin film and on biotin film via a streptavidin arm both in static and dynamic conditions compared with PEG-graft-PLA NPs, the proven nonspecific protein-resistant NPs. The specific binding of biotin-graft-PLA NPs with streptavidin and with biotin using streptavidin arm, as well as its entrapment and controlled release for naproxen, suggest potential applications in targeted drug delivery. PMID:22334778

Microstructural and electrochemical characterization of Ni/Ti/sub 2/N composite coating for sintered NdFeB permanent magnets

International Nuclear Information System (INIS)

Ali, A.; Ahmad, A.; Deen, K.M.; Ahmad, R.

2009-01-01

Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in humid or moist environments. The paper presents the anticorrosion characteristics of a novel Ni/Ti/sub 2/N composite coating applied through electrodeposition and cathodic arc physical vapour deposition (CAPVD) to sintered NdFeB permanent magnets. The performance of composite coating was evaluated in simulated marine environment with the help of dc polarization techniques. The rate of coating degradation was also determined by employing ac electrochemical impedance spectroscopy (EIS). The coating morphology and surface chemistry were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for identification of component phases in the coating-substrate system. The results showed that the composite coating provided an adequately improved corrosion protection to the sintered NdFeB magnets in the simulated marine environment compared to the earlier reported ceramic and metallic coatings. The composite coating did not damage the magnetic properties of coating-substrate system that remained at par with the ceramic and nickel coating having copper interlayer. (author)

Experiment list: SRX319556 [Chip-atlas[Archive