Nanoscale layer-selective readout of magnetization direction from a magnetic multilayer using a spin-torque oscillator

International Nuclear Information System (INIS)

Suto, Hirofumi; Nagasawa, Tazumi; Kudo, Kiwamu; Mizushima, Koichi; Sato, Rie

2014-01-01

Technology for detecting the magnetization direction of nanoscale magnetic material is crucial for realizing high-density magnetic recording devices. Conventionally, a magnetoresistive device is used that changes its resistivity in accordance with the direction of the stray field from an objective magnet. However, when several magnets are near such a device, the superposition of stray fields from all the magnets acts on the sensor, preventing selective recognition of their individual magnetization directions. Here we introduce a novel readout method for detecting the magnetization direction of a nanoscale magnet by use of a spin-torque oscillator (STO). The principles behind this method are dynamic dipolar coupling between an STO and a nanoscale magnet, and detection of ferromagnetic resonance (FMR) of this coupled system from the STO signal. Because the STO couples with a specific magnet by tuning the STO oscillation frequency to match its FMR frequency, this readout method can selectively determine the magnetization direction of the magnet. (papers)

Immunoliposome-mediated delivery of neomycin phosphotransferase for the lineage-specific selection of differentiated/committed stem cell progenies: potential advantages over transfection with marker genes, fluorescence-activated and magnetic affinity cell-sorting.

Science.gov (United States)

Heng, Boon Chin; Cao, Tong

2005-01-01

A major challenge in the therapeutic application of stem cells in regenerative medicine is the lineage-specific selection of their committed/differentiated progenies for transplantation. This is necessary to avoid engraftment of undesired lineages at the transplantation site, i.e. fibroblastic scar tissue, as well as to enhance the efficacy of transplantation therapy. Commonly used techniques for lineage-specific selection of committed/differentiated stem cell progenies include marker gene transfection, fluorescence-activated (FACS) and magnetic-affinity (MACS) cell-sorting. Nevertheless, these have their disadvantages for therapeutic applications. Marker gene transfection invariably leads to permanent genetic modification of stem cells, which in turn limits their use in human clinical therapy due to overwhelming ethical and safety concerns. FACS requires expensive instrumentation and highly-skilled personnel, and is unsuited for handling bulk quantities of cells that would almost certainly be required for transplantation therapy. MACS is a cheaper alternative, but the level of purity attained is also reduced. A possible novel approach that has yet to be investigated is immunoliposome-mediated delivery of neomycin phosphotranferase (NPT) for lineage-specific selection of stem cell progenies. This would avoid permanent genetic modification to the cell, unlike recombinant NPT expression linked to activation of specific promoter sequences. Moreover, it could potentially provide a much more practical and cost-effective alternative for handling bulk quantities of cells that would be required for transplantation therapy, as compared to FACS or MACS. As such, this alternative approach needs to be rigorously investigated, in view of its potentially useful applications in stem cell therapeutics.

Microstructure and Magnetic Properties of Magnetic Material Fabricated by Selective Laser Melting

Science.gov (United States)

Jhong, Kai Jyun; Huang, Wei-Chin; Lee, Wen Hsi

Selective Laser Melting (SLM) is a powder-based additive manufacturing which is capable of producing parts layer-by-layer from a 3D CAD model. The aim of this study is to adopt the selective laser melting technique to magnetic material fabrication. [1]For the SLM process to be practical in industrial use, highly specific mechanical properties of the final product must be achieved. The integrity of the manufactured components depend strongly on each single laser-melted track and every single layer, as well as the strength of the connections between them. In this study, effects of the processing parameters, such as the space distance of surface morphology is analyzed. Our hypothesis is that when a magnetic product is made by the selective laser melting techniques instead of traditional techniques, the finished component will have more precise and effective properties. This study analyzed the magnitudes of magnetic properties in comparison with different parameters in the SLM process and compiled a completed product to investigate the efficiency in contrast with products made with existing manufacturing processes.

A nanowire magnetic memory cell based on a periodic magnetic superlattice

International Nuclear Information System (INIS)

Song, J-F; Bird, J P; Ochiai, Y

2005-01-01

We analyse the operation of a semiconductor nanowire-based memory cell. Large changes in the nanowire conductance result when the magnetization of a periodic array of nanoscale magnetic gates, which comprise the other key component of the memory cell, is switched between distinct configurations by an external magnetic field. The resulting conductance change provides the basis for a robust memory effect, which can be implemented in a semiconductor structure compatible with conventional semiconductor integrated circuits

Multifunctional biocompatible graphene oxide quantum dots decorated magnetic nanoplatform for efficient capture and two-photon imaging of rare tumor cells.

Science.gov (United States)

Shi, Yongliang; Pramanik, Avijit; Tchounwou, Christine; Pedraza, Francisco; Crouch, Rebecca A; Chavva, Suhash Reddy; Vangara, Aruna; Sinha, Sudarson Sekhar; Jones, Stacy; Sardar, Dhiraj; Hawker, Craig; Ray, Paresh Chandra

2015-05-27

Circulating tumor cells (CTCs) are extremely rare cells in blood containing billions of other cells. The selective capture and identification of rare cells with sufficient sensitivity is a real challenge. Driven by this need, this manuscript reports the development of a multifunctional biocompatible graphene oxide quantum dots (GOQDs) coated, high-luminescence magnetic nanoplatform for the selective separation and diagnosis of Glypican-3 (GPC3)-expressed Hep G2 liver cancer tumor CTCs from infected blood. Experimental data show that an anti-GPC3-antibody-attached multifunctional nanoplatform can be used for selective Hep G2 hepatocellular carcinoma tumor cell separation from infected blood containing 10 tumor cells/mL of blood in a 15 mL sample. Reported data indicate that, because of an extremely high two-photon absorption cross section (40530 GM), an anti-GPC3-antibody-attached GOQDs-coated magnetic nanoplatform can be used as a two-photon luminescence platform for selective and very bright imaging of a Hep G2 tumor cell in a biological transparency window using 960 nm light. Experimental results with nontargeted GPC3(-) and SK-BR-3 breast cancer cells show that multifunctional-nanoplatform-based cell separation, followed by two-photon imaging, is highly selective for Hep G2 hepatocellular carcinoma tumor cells.

Magnetic field exposure stiffens regenerating plant protoplast cell walls.

Science.gov (United States)

Haneda, Toshihiko; Fujimura, Yuu; Iino, Masaaki

2006-02-01

Single suspension-cultured plant cells (Catharanthus roseus) and their protoplasts were anchored to a glass plate and exposed to a magnetic field of 302 +/- 8 mT for several hours. Compression forces required to produce constant cell deformation were measured parallel to the magnetic field by means of a cantilever-type force sensor. Exposure of intact cells to the magnetic field did not result in any changes within experimental error, while exposure of regenerating protoplasts significantly increased the measured forces and stiffened regenerating protoplasts. The diameters of intact cells or regenerating protoplasts were not changed after exposure to the magnetic field. Measured forces for regenerating protoplasts with and without exposure to the magnetic field increased linearly with incubation time, with these forces being divided into components based on the elasticity of synthesized cell walls and cytoplasm. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye, and no changes were noted after exposure to the magnetic field. Analysis suggested that exposure to the magnetic field roughly tripled the Young's modulus of the newly synthesized cell wall without any lag.

Non-chemotoxic induction of cancer cell death using magnetic nanowires

KAUST Repository

Contreras, Maria F.; Sougrat, Rachid; Zaher, Amir Omar; Ravasi, Timothy; Kosel, Jü rgen

2015-01-01

In this paper, we show that magnetic nanowires with weak magnetic fields and low frequencies can induce cell death via a mechanism that does not involve heat production. We incubated colon cancer cells with two concentrations (2.4 and 12 μg/mL) of nickel nanowires that were 35 nm in diameter and exposed the cells and nanowires to an alternating magnetic field (0.5 mT and 1 Hz or 1 kHz) for 10 or 30 minutes. This low-power field exerted a force on the magnetic nanowires, causing a mechanical disturbance to the cells. Transmission electron microscopy images showed that the nanostructures were internalized into the cells within 1 hour of incubation. Cell viability studies showed that the magnetic field and the nanowires separately had minor deleterious effects on the cells; however, when combined, the magnetic field and nanowires caused the cell viability values to drop by up to 39%, depending on the strength of the magnetic field and the concentration of the nanowires. Cell membrane leakage experiments indicated membrane leakage of 20%, suggesting that cell death mechanisms induced by the nanowires and magnetic field involve some cell membrane rupture. Results suggest that magnetic nanowires can kill cancer cells. The proposed process requires simple and low-cost equipment with exposure to only very weak magnetic fields for short time periods. © 2015 Contreras et al.

Non-chemotoxic induction of cancer cell death using magnetic nanowires

KAUST Repository

Contreras, Maria F.

2015-03-01

In this paper, we show that magnetic nanowires with weak magnetic fields and low frequencies can induce cell death via a mechanism that does not involve heat production. We incubated colon cancer cells with two concentrations (2.4 and 12 μg/mL) of nickel nanowires that were 35 nm in diameter and exposed the cells and nanowires to an alternating magnetic field (0.5 mT and 1 Hz or 1 kHz) for 10 or 30 minutes. This low-power field exerted a force on the magnetic nanowires, causing a mechanical disturbance to the cells. Transmission electron microscopy images showed that the nanostructures were internalized into the cells within 1 hour of incubation. Cell viability studies showed that the magnetic field and the nanowires separately had minor deleterious effects on the cells; however, when combined, the magnetic field and nanowires caused the cell viability values to drop by up to 39%, depending on the strength of the magnetic field and the concentration of the nanowires. Cell membrane leakage experiments indicated membrane leakage of 20%, suggesting that cell death mechanisms induced by the nanowires and magnetic field involve some cell membrane rupture. Results suggest that magnetic nanowires can kill cancer cells. The proposed process requires simple and low-cost equipment with exposure to only very weak magnetic fields for short time periods. © 2015 Contreras et al.

Magnetic manipulation of particles and cells in ferrofluid flow through straight microchannels using two magnets

Science.gov (United States)

Zeng, Jian

Microfluidic devices have been increasingly used in the past two decades for particle and cell manipulations in many chemical and biomedical applications. A variety of force fields have been demonstrated to control particle and cell transport in these devices including electric, magnetic, acoustic, and optical forces etc. Among these particle handling techniques, the magnetic approach provides clear advantages over others such as low cost, noninvasive, and free of fluid heating issues. However, the current knowledge of magnetic control of particle transport is still very limited, especially lacking is the handling of diamagnetic particle. This thesis is focused on the magnetic manipulation of diamagnetic particles and cells in ferrofluid flow through the use of a pair of permanent magnets. By varying the configuration of the two magnets, diverse operations of particles and cells is implemented in a straight microchannel that can potentially be integrated into lab-on-a-chip devices for various applications. First, an approach for embedding two, symmetrically positioned, repulsive permanent magnets about a straight rectangular microchannel in a PDMS-based microfluidic device is developed for particle focusing. Focusing particles and cells into a tight stream is often required in order for continuous detection, counting, and sorting. The closest distance between the magnets is limited only by the size of the magnets involved in the fabrication process. The device is used to implement and investigate the three-dimensional magnetic focusing of polystyrene particles in ferrofluid microflow with both top-view and side-view visualizations. The effects of flow speed and particle size on the particle focusing effectiveness are studied. This device is also applied to magnetically focus yeast cells in ferrofluid, which proves to be biocompatible as verified by cell viability test. In addition, an analytical model is developed and found to be able to predict the experimentally

The Development of Magnetic Molecules for the Selective Removal of Contaminants

International Nuclear Information System (INIS)

Bushart, S.P.; Bradbury, D.; Elder, G.; Duffield, J.; Pascual, I.; Ratcliffe, N.

2006-01-01

'Magnetic molecules' are a new type of decontaminant for removing dilute dissolved contaminants from solution. Magnetic molecules have a specific ion exchange function to selectively react with a particular type of ionic contamination in a liquid solution. The magnetic molecules also have a very small magnetic ferritin core (ferritin is an iron-III mammalian storage protein having about 10 nm diameter), which enables the magnetic molecule to be removed from solution by magnetic filtration. The ion exchange function is attached to the magnetic ferritin core by organic reaction sequences. The ion exchange function selectively bonds to a specific type of contaminant ion. For example, ion exchange functions can selectively target radioactive contaminant ions such as cobalt, cesium and plutonium. The procedure for decontamination is that the appropriate magnetic molecule (which targets the contaminant which it is desired to remove) is added to the solution and the solution is then passed through a magnetic filter. The contaminant binds to the magnetic molecule and is then removed by the magnetic filter. The magnetic molecule/contaminant can then be recovered from the magnetic filter by back-washing. Work has been undertaken towards the development of magnetic molecules for use as radioactive decontaminants for radioactive waste management purposes. Previously we have reported on the functionalization of ferritin with the chelating agent DTPA and have shown that this can be used to bind Ca(II) in solution and separate it from Na(I) ions by the process of equilibrium dialysis. Approximately 100 DTPA molecules could be bound to the surface of the ferritin molecule. Synthetic conditions have been optimised, and which will be reported here, ferritin has been functionalized with approximately 1200 DTPA molecules per mole of ferritin and used successfully to achieve a quantitative separation of Co(II) from Cs(I) ions by equilibrium dialysis. This separation has been carried

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

Measurements of magnetic anisotropy in sickle cells

International Nuclear Information System (INIS)

Salvo Souza, L.H. de.

1982-03-01

Room temperature magnetic measurements in deoxigenated sickle cells showed the existence of magnetic anisotropy, Δchi=1,29 x 10 -3 . This effect was supposed paramagnetic and considered to be due to the iron atoms of the hemoglobin molecules which are one over the other, forming ordered chains inside the erythrocytes. Low temperature (liquid He - 4,2K) measurements of the magnetic anisotropy of sickle cells and normal red blood cells diluted in a cryoprotector was made to confirm the paramagnetic origin of the fenomena. For that purpose it was used a superconductor magnetometer coupled to a SQUID, developed in the 'Laboratorio do Estado Solido do Departamento de Fisica da PUC-RJ'. The results obtained seem to confirm the expected paramagnetic anisotropy and, furthermore, suggest the presence of magnetic interactions among the iron atoms in the sickle cells samples. (Author) [pt

Selection of Shared and Neoantigen-Reactive T Cells for Adoptive Cell Therapy Based on CD137 Separation

Directory of Open Access Journals (Sweden)

Sivan Seliktar-Ofir

2017-10-01

Full Text Available Adoptive cell therapy (ACT of autologous tumor infiltrating lymphocytes (TIL is an effective immunotherapy for patients with solid tumors, yielding objective response rates of around 40% in refractory patients with metastatic melanoma. Most clinical centers utilize bulk, randomly isolated TIL from the tumor tissue for ex vivo expansion and infusion. Only a minor fraction of the administered T cells recognizes tumor antigens, such as shared and mutation-derived neoantigens, and consequently eliminates the tumor. Thus, there are many ongoing effects to identify and select tumor-specific TIL for therapy; however, those approaches are very costly and require months, which is unreasonable for most metastatic patients. CD137 (4-1BB has been identified as a co-stimulatory marker, which is induced upon the specific interaction of T cells with their target cell. Therefore, CD137 can be a useful biomarker and an important tool for the selection of tumor-reactive T cells. Here, we developed and validated a simple and time efficient method for the selection of CD137-expressing T cells for therapy based on magnetic bead separation. CD137 selection was performed with clinical grade compliant reagents, and TIL were expanded in a large-scale manner to meet cell numbers required for the patient setting in a GMP facility. For the first time, the methodology was designed to comply with both clinical needs and limitations, and its feasibility was assessed. CD137-selected TIL demonstrated significantly increased antitumor reactivity and were enriched for T cells recognizing neoantigens as well as shared tumor antigens. CD137-based selection enabled the enrichment of tumor-reactive T cells without the necessity of knowing the epitope specificity or the antigen type. The direct implementation of the CD137 separation method to the cell production of TIL may provide a simple way to improve the clinical efficiency of TIL ACT.

Fundamentals and Application of Magnetic Particles in Cell Isolation and Enrichment

Science.gov (United States)

Plouffe, Brian D.; Murthy, Shashi K.; Lewis, Laura H.

2014-01-01

Magnetic sorting using magnetic beads has become a routine methodology for the separation of key cell populations from biological suspensions. Due to the inherent ability of magnets to provide forces at a distance, magnetic cell manipulation is now a standardized process step in numerous processes in tissue engineering, medicine, and in fundamental biological research. Herein we review the current status of magnetic particles to enable isolation and separation of cells, with a strong focus on the fundamental governing physical phenomena, properties and syntheses of magnetic particles and on current applications of magnet-based cell separation in laboratory and clinical settings. We highlight the contribution of cell separation to biomedical research and medicine and detail modern cell separation methods (both magnetic and non-magnetic). In addition to a review of the current state-of-the-art in magnet-based cell sorting, we discuss current challenges and available opportunities for further research, development and commercialization of magnetic particle-based cell separation systems. PMID:25471081

Design of a novel magnetic platform for cell manipulation

Science.gov (United States)

Lucarini, Gioia; Iacovacci, Veronica; Gouveia, Pedro J.; Ricotti, Leonardo; Menciassi, Arianna

2018-02-01

Cell manipulation tasks, especially in lab-on-a-chip applications for personalized medicine, could greatly benefit from mobile untethered microdevices able to wirelessly navigate in fluidic environments by means of magnetic fields. In this paper, the design, fabrication and testing of a magnetic platform enabling the controlled locomotion and immersion of microrobots placed at the air/liquid interface is proposed and exploited for cell manipulation. The proposed microrobot consists of a polymeric magnetic thin film that acts as cell transporter and a specific coating strategy, devised to enhance a safe cancer cell adhesion to the magnetic film. Experimental results demonstrated an overall cell viability and a fine control of magnetic microrobot locomotion. The proposed technologies are promising in view of future cell manipulation tasks for personalized medicine applications.

Non-chemotoxic induction of cancer cell death using magnetic nanowires

Directory of Open Access Journals (Sweden)

Contreras MF

2015-03-01

Full Text Available Maria F Contreras,1 Rachid Sougrat,2 Amir Zaher,3 Timothy Ravasi,1,3 Jürgen Kosel3 1Division of Biological and Environmental Sciences and Engineering, 2Advanced Nanofabrication Imaging and Characterization, 3Division of Computer, Electrical and Mathematical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia Abstract: In this paper, we show that magnetic nanowires with weak magnetic fields and low frequencies can induce cell death via a mechanism that does not involve heat production. We incubated colon cancer cells with two concentrations (2.4 and 12 µg/mL of nickel nanowires that were 35 nm in diameter and exposed the cells and nanowires to an alternating magnetic field (0.5 mT and 1 Hz or 1 kHz for 10 or 30 minutes. This low-power field exerted a force on the magnetic nanowires, causing a mechanical disturbance to the cells. Transmission electron microscopy images showed that the nanostructures were internalized into the cells within 1 hour of incubation. Cell viability studies showed that the magnetic field and the nanowires separately had minor deleterious effects on the cells; however, when combined, the magnetic field and nanowires caused the cell viability values to drop by up to 39%, depending on the strength of the magnetic field and the concentration of the nanowires. Cell membrane leakage experiments indicated membrane leakage of 20%, suggesting that cell death mechanisms induced by the nanowires and magnetic field involve some cell membrane rupture. Results suggest that magnetic nanowires can kill cancer cells. The proposed process requires simple and low-cost equipment with exposure to only very weak magnetic fields for short time periods. Keywords: cell death induction, low frequency alternating magnetic field, nanomedicine, nanowire internalization, nickel nanowires

Biofunctionalized Magnetic Nanowires

KAUST Repository

Kosel, Jurgen

2013-12-19

Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

Biofunctionalized Magnetic Nanowires

KAUST Repository

Kosel, Jü rgen; Ravasi, Timothy; Contreras Gerenas, Maria Fernanda

2013-01-01

Magnetic nanowires can be used as an alternative method overcoming the limitations of current cancer treatments that lack specificity and are highly cytotoxic. Nanowires are developed so that they selectively attach to cancer cells via antibodies, potentially destroying them when a magnetic field induces their vibration. This will transmit a mechanical force to the targeted cells, which is expected to induce apoptosis on the cancer cells.

Diffusion in a tokamak with helical magnetic cells

International Nuclear Information System (INIS)

Wakatani, Masahiro

1975-05-01

In a tokamak with helical magnetic cells produced by a resonant helical magnetic field, diffusion in the collisional regime is studied. The diffusion coefficient is greatly enhanced near the resonant surface even for a weak helical magnetic field. A theoretical model for disruptive instabilities based on the enhanced transport due to helical magnetic cells is discussed. This may explain experiments of the tokamak with resonant helical fields qualitatively. (author)

Application of magnetic carriers to two examples of quantitative cell analysis

Energy Technology Data Exchange (ETDEWEB)

Zhou, Chen; Qian, Zhixi; Choi, Young Suk; David, Allan E. [Department of Chemical Engineering, 212 Ross Hall, Auburn University, Auburn, AL 36849 (United States); Todd, Paul, E-mail: pwtodd@hotmail.com [Techshot, Inc., 7200 Highway 150, Greenville, IN 47124 (United States); Hanley, Thomas R. [Department of Chemical Engineering, 212 Ross Hall, Auburn University, Auburn, AL 36849 (United States)

2017-04-01

The use of magnetophoretic mobility as a surrogate for fluorescence intensity in quantitative cell analysis was investigated. The objectives of quantitative fluorescence flow cytometry include establishing a level of labeling for the setting of parameters in fluorescence activated cell sorters (FACS) and the determination of levels of uptake of fluorescently labeled substrates by living cells. Likewise, the objectives of quantitative magnetic cytometry include establishing a level of labeling for the setting of parameters in flowing magnetic cell sorters and the determination of levels of uptake of magnetically labeled substrates by living cells. The magnetic counterpart to fluorescence intensity is magnetophoretic mobility, defined as the velocity imparted to a suspended cell per unit of magnetic ponderomotive force. A commercial velocimeter available for making this measurement was used to demonstrate both applications. Cultured Gallus lymphoma cells were immunolabeled with commercial magnetic beads and shown to have adequate magnetophoretic mobility to be separated by a novel flowing magnetic separator. Phagocytosis of starch nanoparticles having magnetic cores by cultured Chinese hamster ovary cells, a CHO line, was quantified on the basis of magnetophoretic mobility. - Highlights: • Commercial particle tracking velocimetry measures magnetophoretic mobility of labeled cells. • Magnetically labeled tumor cells were shown to have adequate mobility for capture in a specific sorter. • The kinetics of nonspecific endocytosis of magnetic nanomaterials by CHO cells was characterized. • Magnetic labeling of cells can be used like fluorescence flow cytometry for quantitative cell analysis.

Single cell detection using a magnetic zigzag nanowire biosensor.

Science.gov (United States)

Huang, Hao-Ting; Ger, Tzong-Rong; Lin, Ya-Hui; Wei, Zung-Hang

2013-08-07

A magnetic zigzag nanowire device was designed for single cell biosensing. Nanowires with widths of 150, 300, 500, and 800 nm were fabricated on silicon trenches by electron beam lithography, electron beam evaporation, and lift-off processes. Magnetoresistance measurements were performed before and after the attachment of a single magnetic cell to the nanowires to characterize the magnetic signal change due to the influence of the magnetic cell. Magnetoresistance responses were measured in different magnetic field directions, and the results showed that this nanowire device can be used for multi-directional detection. It was observed that the highest switching field variation occurred in a 150 nm wide nanowire when the field was perpendicular to the substrate plane. On the other hand, the highest magnetoresistance ratio variation occurred in a 800 nm wide nanowire also when the field was perpendicular to the substrate plane. Besides, the trench-structured substrate proposed in this study can fix the magnetic cell to the sensor in a fluid environment, and the stray field generated by the corners of the magnetic zigzag nanowires has the function of actively attracting the magnetic cells for detection.

Magnetic stem cell targeting to the inner ear

Science.gov (United States)

Le, T. N.; Straatman, L.; Yanai, A.; Rahmanian, R.; Garnis, C.; Häfeli, U. O.; Poblete, T.; Westerberg, B. D.; Gregory-Evans, K.

2017-12-01

Severe sensorineural deafness is often accompanied by a loss of auditory neurons in addition to injury of the cochlear epithelium and hair cell loss. Cochlear implant function however depends on a healthy complement of neurons and their preservation is vital in achieving optimal results. We have developed a technique to target mesenchymal stem cells (MSCs) to a deafened rat cochlea. We then assessed the neuroprotective effect of systematically delivered MSCs on the survival and function of spiral ganglion neurons (SGNs). MSCs were labeled with superparamagnetic nanoparticles, injected via the systemic circulation, and targeted using a magnetized cochlea implant and external magnet. Neurotrophic factor concentrations, survival of SGNs, and auditory function were assessed at 1 week and 4 weeks after treatments and compared against multiple control groups. Significant numbers of magnetically targeted MSCs (>30 MSCs/section) were present in the cochlea with accompanied elevation of brain-derived neurotrophic factor and glial cell-derived neurotrophic factor levels (p < 0.001). In addition we saw improved survival of SGNs (approximately 80% survival at 4 weeks). Hearing threshold levels in magnetically targeted rats were found to be significantly better than those of control rats (p < 0.05). These results indicate that magnetic targeting of MSCs to the cochlea can be accomplished with a magnetized cochlear permalloy implant and an external magnet. The targeted stem cells release neurotrophic factors which results in improved SGN survival and hearing recovery. Combining magnetic cell-based therapy and cochlear implantation may improve cochlear implant function in treating deafness.

Using magnetic resonance imaging to evaluate dendritic cell-based vaccination.

Directory of Open Access Journals (Sweden)

Peter M Ferguson

Full Text Available Cancer immunotherapy with antigen-loaded dendritic cell-based vaccines can induce clinical responses in some patients, but further optimization is required to unlock the full potential of this strategy in the clinic. Optimization is dependent on being able to monitor the cellular events that take place once the dendritic cells have been injected in vivo, and to establish whether antigen-specific immune responses to the tumour have been induced. Here we describe the use of magnetic resonance imaging (MRI as a simple, non-invasive approach to evaluate vaccine success. By loading the dendritic cells with highly magnetic iron nanoparticles it is possible to assess whether the injected cells drain to the lymph nodes. It is also possible to establish whether an antigen-specific response is initiated by assessing migration of successive rounds of antigen-loaded dendritic cells; in the face of a successfully primed cytotoxic response, the bulk of antigen-loaded cells are eradicated on-route to the node, whereas cells without antigen can reach the node unchecked. It is also possible to verify the induction of a vaccine-induced response by simply monitoring increases in draining lymph node size as a consequence of vaccine-induced lymphocyte trapping, which is an antigen-specific response that becomes more pronounced with repeated vaccination. Overall, these MRI techniques can provide useful early feedback on vaccination strategies, and could also be used in decision making to select responders from non-responders early in therapy.

Magnetic cell labeling of primary and stem cell-derived pig hepatocytes for MRI-based cell tracking of hepatocyte transplantation.

Directory of Open Access Journals (Sweden)

Dwayne R Roach

Full Text Available Pig hepatocytes are an important investigational tool for optimizing hepatocyte transplantation schemes in both allogeneic and xenogeneic transplant scenarios. MRI can be used to serially monitor the transplanted cells, but only if the hepatocytes can be labeled with a magnetic particle. In this work, we describe culture conditions for magnetic cell labeling of cells from two different pig hepatocyte cell sources; primary pig hepatocytes (ppHEP and stem cell-derived hepatocytes (PICM-19FF. The magnetic particle is a micron-sized iron oxide particle (MPIO that has been extensively studied for magnetic cell labeling for MRI-based cell tracking. ppHEP could endocytose MPIO with labeling percentages as high as 70%, achieving iron content as high as ~55 pg/cell, with >75% viability. PICM-19FF had labeling >97%, achieving iron content ~38 pg/cell, with viability >99%. Extensive morphological and functional assays indicated that magnetic cell labeling was benign to the cells. The results encourage the use of MRI-based cell tracking for the development and clinical use of hepatocyte transplantation methodologies. Further, these results generally highlight the importance of functional cell assays in the evaluation of contrast agent biocompatibility.

Preparation of poly-L-lysine functionalized magnetic nanoparticles and their influence on viability of cancer cells

Energy Technology Data Exchange (ETDEWEB)

Khmara, I. [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia); Pavol Jozef Safarik University, Faculty of Science, Park Angelinum 9, Kosice (Slovakia); Koneracka, M.; Kubovcikova, M. [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia); Zavisova, V., E-mail: zavisova@saske.sk [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia); Antal, I.; Csach, K.; Kopcansky, P. [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia); Vidlickova, I.; Csaderova, L.; Pastorekova, S.; Zatovicova, M. [Institute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava (Slovakia)

2017-04-01

This study was aimed at development of biocompatible amino-functionalized magnetic nanoparticles as carriers of specific antibodies able to detect and/or target cancer cells. Poly-L-lysine (PLL)-modified magnetic nanoparticle samples with different PLL/Fe{sub 3}O{sub 4} content were prepared and tested to define the optimal PLL/Fe{sub 3}O{sub 4} weight ratio. The samples were characterized for particle size and morphology (SEM, TEM and DLS), and surface properties (zeta potential measurements). The optimal PLL/Fe{sub 3}O{sub 4} weight ratio of 1.0 based on both zeta potential and DLS measurements was in agreement with the UV/VIS measurements. Magnetic nanoparticles with the optimal PLL content were conjugated with antibody specific for the cancer biomarker carbonic anhydrase IX (CA IX), which is induced by hypoxia, a physiologic stress present in solid tumors and linked with aggressive tumor behavior. CA IX is localized on the cell surface with the antibody-binding epitope facing the extracellular space and is therefore suitable for antibody-based targeting of tumor cells. Here we showed that PLL/Fe{sub 3}O{sub 4} magnetic nanoparticles exhibit cytotoxic activities in a cell type-dependent manner and bind to cells expressing CA IX when conjugated with the CA IX-specific antibody. These data support further investigations of the CA IX antibody-conjugated, magnetic field-guided/activated nanoparticles as tools in anticancer strategies. - Highlights: • Antibody-coupled magnetic nanoparticles can serve for targeting of cancer cells. • Nanoparticle properties depend on poly-L-lysine loading that prevents aggregation. • Nanoparticles show time-, concentration-, and cell type-specific cytotoxicity. • M75 antibody detects the hypoxia-induced tumor biomarker CA IX. • M75-conjugated nanoparticles exhibit selective cell binding and internalization.

Magnetic resonance investigation of magnetic-labeled baker's yeast cells

International Nuclear Information System (INIS)

Godoy Morais, J.P.M.; Azevedo, R.B.; Silva, L.P.; Lacava, Z.G.M.; Bao, S.N.; Silva, O.; Pelegrini, F.; Gansau, C.; Buske, N.; Safarik, I.; Safarikova, M.; Morais, P.C.

2004-01-01

In this study, the interaction of DMSA-coated magnetite nanoparticles (5 and 10 nm core-size) with Saccharomyces cerevisae was investigated using magnetic resonance (MR) and transmission electron microscopy (TEM). The TEM micrographs revealed magnetite nanoparticles attached externally to the cell wall. The MR data support the strong interaction among the nanoparticles supported by the cells. A remarkable shift in the resonance field was used as signature of particle attachment to the cell wall

Effects of high-gradient magnetic fields on living cell machinery

International Nuclear Information System (INIS)

Zablotskii, V; Lunov, O; Kubinova, S; Polyakova, T; Dejneka, A; Sykova, E

2016-01-01

A general interest in biomagnetic effects is related to fundamental studies of the influence of magnetic fields on living objects on the cellular and whole organism levels. Emerging technologies offer new directions for the use of high-gradient magnetic fields to control cell machinery and to understand the intracellular biological processes of the emerging field of nanomedicine. In this review we aim at highlighting recent advances made in identifying fundamental mechanisms by which magnetic gradient forces act on cell fate specification and cell differentiation. The review also provides an analysis of the currently available magnetic systems capable of generating magnetic fields with spatial gradients of up to 10 MT m −1 , with the focus on their suitability for use in cell therapy. Relationships between experimental factors and underlying biophysical mechanisms and assumptions that would ultimately lead to a deeper understanding of cell machinery and the development of more predictive models for the evaluation of the effects of magnetic fields on cells, tissue and organisms are comprehensively discussed. (topical review)

Design features of the solenoid magnets for the central cell of the MFTF-B

International Nuclear Information System (INIS)

Wohlwend, J.W.; Tatro, R.E.; Ring, D.S.

1981-01-01

The 14 superconducting solenoid magnets which form the central cell of the MFTF-B are being designed and fabricated by General Dynamics for the Lawrence Livermore National Laboratory. Each solenoid coil has a mean diameter of five meters and contains 600 turns of a proven conductor type. Structural loading resulting from credible fault events, cooldown and warmup requirements, and manufacturing processes consistent with other MFTF-B magnets have been considered in the selection of 304 LN as the structural material for the magnet. The solenoid magnets are connected by 24 intercoil beams and 20 solid struts which resist the longitudinal seismic and electromagnetic attractive forces and by 24 hanger/side supports which react magnet dead weight and seismic loads. A modular arrangement of two solenoid coils within a vacuum vessel segment allow for sequential checkout and installation

How a High-Gradient Magnetic Field Could Affect Cell Life

Science.gov (United States)

Zablotskii, Vitalii; Polyakova, Tatyana; Lunov, Oleg; Dejneka, Alexandr

2016-01-01

The biological effects of high-gradient magnetic fields (HGMFs) have steadily gained the increased attention of researchers from different disciplines, such as cell biology, cell therapy, targeted stem cell delivery and nanomedicine. We present a theoretical framework towards a fundamental understanding of the effects of HGMFs on intracellular processes, highlighting new directions for the study of living cell machinery: changing the probability of ion-channel on/off switching events by membrane magneto-mechanical stress, suppression of cell growth by magnetic pressure, magnetically induced cell division and cell reprograming, and forced migration of membrane receptor proteins. By deriving a generalized form for the Nernst equation, we find that a relatively small magnetic field (approximately 1 T) with a large gradient (up to 1 GT/m) can significantly change the membrane potential of the cell and thus have a significant impact on not only the properties and biological functionality of cells but also cell fate. PMID:27857227

How a High-Gradient Magnetic Field Could Affect Cell Life

Science.gov (United States)

Zablotskii, Vitalii; Polyakova, Tatyana; Lunov, Oleg; Dejneka, Alexandr

2016-11-01

The biological effects of high-gradient magnetic fields (HGMFs) have steadily gained the increased attention of researchers from different disciplines, such as cell biology, cell therapy, targeted stem cell delivery and nanomedicine. We present a theoretical framework towards a fundamental understanding of the effects of HGMFs on intracellular processes, highlighting new directions for the study of living cell machinery: changing the probability of ion-channel on/off switching events by membrane magneto-mechanical stress, suppression of cell growth by magnetic pressure, magnetically induced cell division and cell reprograming, and forced migration of membrane receptor proteins. By deriving a generalized form for the Nernst equation, we find that a relatively small magnetic field (approximately 1 T) with a large gradient (up to 1 GT/m) can significantly change the membrane potential of the cell and thus have a significant impact on not only the properties and biological functionality of cells but also cell fate.

Fundamentals and application of magnetic particles in cell isolation and enrichment: a review

International Nuclear Information System (INIS)

Plouffe, Brian D; Murthy, Shashi K; Lewis, Laura H

2015-01-01

Magnetic sorting using magnetic beads has become a routine methodology for the separation of key cell populations from biological suspensions. Due to the inherent ability of magnets to provide forces at a distance, magnetic cell manipulation is now a standardized process step in numerous processes in tissue engineering, medicine, and in fundamental biological research. Herein we review the current status of magnetic particles to enable isolation and separation of cells, with a strong focus on the fundamental governing physical phenomena, properties and syntheses of magnetic particles and on current applications of magnet-based cell separation in laboratory and clinical settings. We highlight the contribution of cell separation to biomedical research and medicine and detail modern cell-separation methods (both magnetic and non-magnetic). In addition to a review of the current state-of-the-art in magnet-based cell sorting, we discuss current challenges and available opportunities for further research, development and commercialization of magnetic particle-based cell-separation systems. (review article)

Cell behaviors on magnetic electrospun poly-D, L-lactide nanofibers

International Nuclear Information System (INIS)

Li, Long; Yang, Guang; Li, Jinrong; Ding, Shan; Zhou, Shaobing

2014-01-01

It is widely accepted that magnetic fields have an influence on cell behaviors, but the effects are still not very clear since the magnetic field's type, intensity and exposure time are different. In this study, a static magnetic field (SMF) in moderate intensity (10 mT) was employed to investigate its effect on osteoblast and 3T3 fibroblast cell behaviors cultured respectively with magnetic polymer nanofiber mats. The magnetic mats composed of random oriented or aligned polymer nanofibers were fabricated by electrospinning the mixed solution of poly-D, L-lactide (PLA) and iron oxide nanoparticles. The fiber morphology was characterized by scanning electron microscopy (SEM), the nanoparticle distribution in fiber matrix was measured with transmission electron microscope (TEM). Mechanical properties of nanofiber mats are studied by uniaxial tensile test. The results showed the nanofibers loaded with magnetic nanoparticles displayed excellent magnetic responsibility and biodegradability. In vitro cytotoxicity analysis demonstrated that the osteoblast proliferation of all fiber mats stimulated with or without SMF was increased with the increase of the culturing days. Furthermore, in the horizontal SMFs, cell orientation tended to deviate from nanofiber orientation to field direction while the nanofiber orientation is perpendicular to the field direction, while the horizonal direction of SMFs could also direct the cell growth orientation. The magnetic nanofiber mats provide a potential platform to explore the cell behaviors under the stimulation of external magnetic field. - Highlights: • The random oriented and aligned magnetic electrospun nanofibers were prepared. • The nanofibers displayed excellent magnetic responsibility and biodegradability. • The horizonal direction of SMFs could also direct the cell growth orientation

Magnetic domain wall conduits for single cell applications

DEFF Research Database (Denmark)

Donolato, Marco; Torti, A.; Kostesha, Natalie

2011-01-01

The ability to trap, manipulate and release single cells on a surface is important both for fundamental studies of cellular processes and for the development of novel lab-on-chip miniaturized tools for biological and medical applications. In this paper we demonstrate how magnetic domain walls...... walls over 16 hours. Moreover, we demonstrate the controlled transport and release of individual yeast cells via displacement and annihilation of individual domain walls in micro- and nano-sized magnetic structures. These results pave the way to the implementation of magnetic devices based on domain...... walls technology in lab-on-chip systems devoted to accurate individual cell trapping and manipulation....

Advanced cell therapies: targeting, tracking and actuation of cells with magnetic particles.

Science.gov (United States)

Connell, John J; Patrick, P Stephen; Yu, Yichao; Lythgoe, Mark F; Kalber, Tammy L

2015-01-01

Regenerative medicine would greatly benefit from a new platform technology that enabled measurable, controllable and targeting of stem cells to a site of disease or injury in the body. Superparamagnetic iron-oxide nanoparticles offer attractive possibilities in biomedicine and can be incorporated into cells, affording a safe and reliable means of tagging. This review describes three current and emerging methods to enhance regenerative medicine using magnetic particles to guide therapeutic cells to a target organ; track the cells using MRI and assess their spatial localization with high precision and influence the behavior of the cell using magnetic actuation. This approach is complementary to the systemic injection of cell therapies, thus expanding the horizon of stem cell therapeutics.

Detection of molecules and cells using nuclear magnetic resonance with magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Rümenapp, Christine, E-mail: ruemenapp@tum.de [Zentralinstitut für Medizintechnik (IMETUM), Technische Universität München, Garching (Germany); Gleich, Bernhard [Zentralinstitut für Medizintechnik (IMETUM), Technische Universität München, Garching (Germany); Mannherz, Hans Georg [Abteilung für Anatomie und Molekulare Embryologie, Ruhr Universität Bochum, Bochum (Germany); Haase, Axel [Zentralinstitut für Medizintechnik (IMETUM), Technische Universität München, Garching (Germany)

2015-04-15

For the detection of small molecules, proteins or even cells in vitro, functionalised magnetic nanoparticles and nuclear magnetic resonance measurements can be applied. In this work, magnetic nanoparticles with the size of 5–7 nm were functionalised with antibodies to detect two model systems of different sizes, the protein avidin and Saccharomyces cerevisiae as the model organism. The synthesised magnetic nanoparticles showed a narrow size distribution, which was determined using transmission electron microscopy and dynamic light scattering. The magnetic nanoparticles were functionalised with the according antibodies via EDC/NHS chemistry. The binding of the antigen to magnetic nanoparticles was detected through the change in the NMR T{sub 2} relaxation time at 0.5 T (≈21.7 MHz). In case of a specific binding the particles cluster and the T{sub 2} relaxation time of the sample changes. The detection limit in buffer for FITC-avidin was determined to be 1.35 nM and 10{sup 7} cells/ml for S. cerevisiae. For fluorescent microscopy the avidin molecules were labelled with FITC and for the detection of S. cerevisiae the magnetic nanoparticles were additionally functionalised with rhodamine. The binding of the particles to S. cerevisiae and the resulting clustering was also seen by transmission electron microscopy.

Life on magnets: stem cell networking on micro-magnet arrays

Czech Academy of Sciences Publication Activity Database

Zablotskyy, Vitaliy A.; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, D.; Dumas-Bouchiat, F.; Givord, D.; Dempsey, N.; Syková, Eva

2013-01-01

Roč. 8, č. 8 (2013), e70416 E-ISSN 1932-6203 R&D Projects: GA ČR GAP304/11/0653; GA ČR(CZ) GAP304/12/1370 Grant - others:AV ČR(CZ) M100101219 Institutional support: RVO:68378271 ; RVO:68378041 Keywords : micro- magnet * stem cells Subject RIV: BM - Solid Matter Physics ; Magnet ism; FH - Neurology (UEM-P) Impact factor: 3.534, year: 2013

Yeast cells proliferation on various strong static magnetic fields and temperatures

International Nuclear Information System (INIS)

Otabe, E S; Kuroki, S; Nikawa, J; Matsumoto, Y; Ooba, T; Kiso, K; Hayashi, H

2009-01-01

The effect of strong magnetic fields on activities of yeast cells were investigated. Experimental yeast cells were cultured in 5 ml of YPD(Yeast extract Peptone Dextrose) for the number density of yeast cells of 5.0 ±0.2 x 10 6 /ml with various temperatures and magnetic fields up to 10 T. Since the yeast cells were placed in the center of the superconducting magnet, the effect of magnetic force due to the diamagnetism and magnetic gradient was negligibly small. The yeast suspension was opened to air and cultured in shaking condition. The number of yeast cells in the yeast suspension was counted by a counting plate with an optical microscope, and the time dependence of the number density of yeast cells was measured. The time dependence of the number density of yeast cells, ρ, of initial part is analyzed in terms of Malthus equation as given by ρ = ρo exp(kt), where k is the growth coefficient. It is found that, the growth coefficient under the magnetic field is suppressed compared with the control. The growth coefficient decreasing as increasing magnetic field and is saturated at about 5 T. On the other hand, it is found that the suppression of growth of yeast cells by the magnetic field is diminished at high temperatures.

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

Collection of ions in a plasma by magnetic field acceleration with selective polarization

International Nuclear Information System (INIS)

Forsen, H.K.

1976-01-01

Method and apparatus are described for generating and accelerating ions in a vapor by use of relatively polarized laser radiation and a magnetic field. As applied to uranium isotope enrichment, a flowing uranium vapor has particles of the 235 U isotope type selectively ionized by laser radiation and the ionized flow is subjected to a transverse gradient in a magnetic field. The magnetic field gradient induces an acceleration on the ionized particles of 235 U which deflects them from their normal flow path toward a collecting structure. High magnetic field and corresponding high ion accelerations are achieved without loss in ionization selectivity by maintaining a polarization between the applied laser radiation and magnetic field which minimizes Zeeman splitting of the uranium energy states

Targeted cancer cell death induced by biofunctionalized magnetic nanowires

KAUST Repository

Contreras, Maria F.; Ravasi, Timothy; Kosel, Jü rgen

2014-01-01

Magnetic micro and nanomaterials are increasingly interesting for biomedical applications since they possess many advantageous properties: they can become biocompatible, they can be functionalized to target specific cells and they can be remotely manipulated by magnetic fields. The goal of this study is to use antibody-functionalized nickel nanowires (Ab-NWs) as an alternative method in cancer therapy overcoming the limitations of current treatments that lack specificity and are highly cytotoxic. Ab-NWs have been incubated with cancer cells and a 12% drop on cell viability was observed for a treatment of only 10 minutes and an alternating magnetic field of low intensity and low frequency. It is believed that the Ab-NWs vibrate transmitting a mechanical force to the targeted cells inducing cell death. © 2014 IEEE.

Targeted cancer cell death induced by biofunctionalized magnetic nanowires

KAUST Repository

Contreras, Maria F.

2014-02-01

Magnetic micro and nanomaterials are increasingly interesting for biomedical applications since they possess many advantageous properties: they can become biocompatible, they can be functionalized to target specific cells and they can be remotely manipulated by magnetic fields. The goal of this study is to use antibody-functionalized nickel nanowires (Ab-NWs) as an alternative method in cancer therapy overcoming the limitations of current treatments that lack specificity and are highly cytotoxic. Ab-NWs have been incubated with cancer cells and a 12% drop on cell viability was observed for a treatment of only 10 minutes and an alternating magnetic field of low intensity and low frequency. It is believed that the Ab-NWs vibrate transmitting a mechanical force to the targeted cells inducing cell death. © 2014 IEEE.

Selective binding and magnetic separation of His-tagged proteins using Fe3O4/PAM/NTA-Ni2+ Magnetic Nanoparticles

Science.gov (United States)

Guo, Huiling; Li, Mengyun; Tu, Shu; Sun, Honghao

2018-03-01

Fe3O4 nanoparticles coated with polyacrylamide (PAM) were synthesized. The magnetic core, with an average hydrodynamic size of 235.5 nm, allowed the magnetic nanoparticles (MNPs) rapid separation from solutions under an external magnetic field. NTA-Ni2+ was modified on the surface of Fe3O4/PAM MNPs to selectively trap his-tagged green fluorescent protein (GFP). The results showed that Fe3O4/PAM/NTA-Ni2+ MNPs exhibited remarkable capability of selective binding and separating his-tagged GFP. The adsorption efficiency was 93.37%.

Pulsed Magnetic Field Improves the Transport of Iron Oxide Nanoparticles through Cell Barriers

Science.gov (United States)

Min, Kyoung Ah; Shin, Meong Cheol; Yu, Faquan; Yang, Meizhu; David, Allan E.; Yang, Victor C.; Rosania, Gus R.

2013-01-01

Understanding how a magnetic field affects the interaction of magnetic nanoparticles (MNPs) with cells is fundamental to any potential downstream applications of MNPs as gene and drug delivery vehicles. Here, we present a quantitative analysis of how a pulsed magnetic field influences the manner in which MNPs interact with, and penetrate across a cell monolayer. Relative to a constant magnetic field, the rate of MNP uptake and transport across cell monolayers was enhanced by a pulsed magnetic field. MNP transport across cells was significantly inhibited at low temperature under both constant and pulsed magnetic field conditions, consistent with an active mechanism (i.e. endocytosis) mediating MNP transport. Microscopic observations and biochemical analysis indicated that, in a constant magnetic field, transport of MNPs across the cells was inhibited due to the formation of large (>2 μm) magnetically-induced MNP aggregates, which exceeded the size of endocytic vesicles. Thus, a pulsed magnetic field enhances the cellular uptake and transport of MNPs across cell barriers relative to a constant magnetic field by promoting accumulation while minimizing magnetically-induced MNP aggregates at the cell surface. PMID:23373613

Quantitative Magnetization Transfer Imaging in Human Brain at 3 T via Selective Inversion Recovery

OpenAIRE

Dortch, Richard D.; Li, Ke; Gochberg, Daniel F.; Welch, E. Brian; Dula, Adrienne N.; Tamhane, Ashish A.; Gore, John C.; Smith, Seth A.

2011-01-01

Quantitative magnetization transfer imaging yields indices describing the interactions between free water protons and immobile, macromolecular protons—including the macromolecular to free pool size ratio (PSR) and the rate of magnetization transfer between pools kmf. This study describes the first implementation of the selective inversion recovery quantitative magnetization transfer method on a clinical 3.0-T scanner in human brain in vivo. Selective inversion recovery data were acquired at 1...

Magnetically insulated fission electric cells for direct energy conversion

International Nuclear Information System (INIS)

Slutz, S.A.; Seidel, D.B.; Lipinski, R.J.; Rochau, G.E.; Brown, L.C.

2003-01-01

The principles of fission electric cells are reviewed. A detailed Monte Carlo model of the efficiency of a fission electric cell is presented and a theory of magnetically insulated fission electric cells (MIFECs) is developed. It is shown that the low operating voltages observed in previous MIFEC experiments were due to nonoptimal magnetic field profiles. Improved magnetic field profiles are presented. It is further shown that the large electric field present in a MIFEC limits the structure of the cathode and can lead to a displacement instability of the cathode toward the anode. This instability places constraints on the number of cells that can be strung together without some external cathode support. The large electric field stress also leads to electrical surface breakdown of the cathode. It is shown that this leads to the formation of a virtual cathode resulting in geometry constraints for spherical cells. Finally it is shown that the requirements of magnetic insulation and high efficiency leads to very low average density of the fissile material. Thus a reactor using fission electric cells for efficient direct energy conversion will be large and require a very large number of cells. This could be mitigated somewhat by the use of exotic fuels

Porcine Dental Epithelial Cells Differentiated in a Cell Sheet Constructed by Magnetic Nanotechnology

Directory of Open Access Journals (Sweden)

Wataru Koto

2017-10-01

Full Text Available Magnetic nanoparticles (MNPs are widely used in medical examinations, treatments, and basic research, including magnetic resonance imaging, drug delivery systems, and tissue engineering. In this study, MNPs with magnetic force were applied to tissue engineering for dental enamel regeneration. The internalization of MNPs into the odontogenic cells was observed by transmission electron microscopy. A combined cell sheet consisting of dental epithelial cells (DECs and dental mesenchymal cells (DMCs (CC sheet was constructed using magnetic force-based tissue engineering technology. The result of the iron staining indicated that MNPs were distributed ubiquitously over the CC sheet. mRNA expression of enamel differentiation and basement membrane markers was examined in the CC sheet. Immunostaining showed Collagen IV expression at the border region between DEC and DMC layers in the CC sheet. These results revealed that epithelial–mesenchymal interactions between DEC and DMC layers were caused by bringing DECs close to DMCs mechanically by magnetic force. Our study suggests that the microenvironment in the CC sheet might be similar to that during the developmental stage of a tooth bud. In conclusion, a CC sheet employing MNPs could be developed as a novel and unique graft for artificially regenerating dental enamel.

Magnetization Dynamics in Two Novel Current-Driven Spintronic Memory Cell Structures

KAUST Repository

Velazquez-Rizo, Martin

2017-07-01

In this work, two new spintronic memory cell structures are proposed. The first cell uses the diffusion of polarized spins into ferromagnets with perpendicular anisotropy to tilt their magnetization followed by their dipolar coupling to a fixed magnet (Bhowmik et al., 2014). The possibility of setting the magnetization to both stable magnetization states in a controlled manner using a similar concept remains unknown, but the proposed structure poses to be a solution to this difficulty. The second cell proposed takes advantage of the multiple stable magnetic states that exist in ferromagnets with configurational anisotropy and also uses spin torques to manipulate its magnetization. It utilizes a square-shaped ferromagnet whose stable magnetization has preferred directions along the diagonals of the square, giving four stable magnetic states allowing to use the structure as a multi-bit memory cell. Both devices use spin currents generated in heavy metals by the Spin Hall effect present in these materials. Among the advantages of the structures proposed are their inherent non-volatility and the fact that there is no need for applying external magnetic fields during their operation, which drastically improves the energy efficiency of the devices. Computational simulations using the Object Oriented Micromagnetic Framework (OOMMF) software package were performed to study the dynamics of the magnetization process in both structures and predict their behavior. Besides, we fabricated a 4-terminal memory cell with configurational anisotropy similar to the device proposed, and found four stable resistive states on the structure, proving the feasibility of this technology for implementation of high-density, non-volatile memory cells.

Effects of high-gradient magnetic fields on living cell machinery

Czech Academy of Sciences Publication Activity Database

Zablotskyy, V.; Lunov, O.; Kubinová, Šárka; Polyakova, T.; Syková, Eva; Dejneka, A.

2016-01-01

Roč. 49, č. 2016 (2016), s. 493003 ISSN 0022-3727 R&D Projects: GA MŠk(CZ) LO1309 Institutional support: RVO:68378041 Keywords : living cell * magnetic gradient force * cell mechanics * stem cell * magnetic field Subject RIV: FP - Other Medical Disciplines Impact factor: 2.588, year: 2016

Magnetic manipulation device for the optimization of cell processing conditions.

Science.gov (United States)

Ito, Hiroshi; Kato, Ryuji; Ino, Kosuke; Honda, Hiroyuki

2010-02-01

Variability in human cell phenotypes make it's advancements in optimized cell processing necessary for personalized cell therapy. Here we propose a strategy of palm-top sized device to assist physically manipulating cells for optimizing cell preparations. For the design of such a device, we combined two conventional approaches: multi-well plate formatting and magnetic cell handling using magnetite cationic liposomes (MCLs). From our previous works, we showed the labeling applications of MCL on adhesive cells for various tissue engineering approaches. To feasibly transfer cells in multi-well plate, we here evaluated the magnetic response of MCL-labeled suspension type cells. The cell handling performance of Jurkat cells proved to be faster and more robust compared to MACS (Magnetic Cell Sorting) bead methods. To further confirm our strategy, prototype palm-top sized device "magnetic manipulation device (MMD)" was designed. In the device, the actual cell transportation efficacy of Jurkat cells was satisfying. Moreover, as a model of the most distributed clinical cell processing, primary peripheral blood mononuclear cells (PBMCs) from different volunteers were evaluated. By MMD, individual PBMCs indicated to have optimum Interleukin-2 (IL-2) concentrations for the expansion. Such huge differences of individual cells indicated that MMD, our proposing efficient and self-contained support tool, could assist the feasible and cost-effective optimization of cell processing in clinical facilities. Copyright (c) 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Synthesis and magnetic properties of size-selected CoPt nanoparticles

International Nuclear Information System (INIS)

Tournus, F.; Blanc, N.; Tamion, A.; Hillenkamp, M.; Dupuis, V.

2011-01-01

CoPt nanoparticles are widely studied, in particular for their potentially very high magnetic anisotropy. However, their magnetic properties can differ from the bulk ones and they are expected to vary with the particle size. In this paper, we report the synthesis and characterization of well-defined CoPt nanoparticle samples produced in ultrahigh vacuum conditions following a physical route: the mass-selected low energy cluster beam deposition technique. This approach relies on an electrostatic deviation of ionized clusters which allows us to easily adjust the particle size, independently from the deposited equivalent thickness (i.e. the surface or volume particle density in a sample). Diluted samples made of CoPt particles, with different diameters, embedded in amorphous carbon are studied by transmission electron microscopy and superconducting interference device magnetometry, which gives access to the magnetic anisotropy energy distribution. We then compare the magnetic properties of two different particle sizes. The results are found to be consistent with an anisotropy constant (including its distribution) which does not evolve with the particle size in the range considered. - Highlights: → Samples of mass-selected CoPt nanoparticles are synthesized by an original physical method. → The magnetic properties of two different particle sizes are compared. → The anisotropy constant (including its dispersion) does not evolve in the range considered. → These results illustrate some invariance properties of ZFC curves.

Selectivity in multiple quantum nuclear magnetic resonance

International Nuclear Information System (INIS)

Warren, W.S.

1980-11-01

The observation of multiple-quantum nuclear magnetic resonance transitions in isotropic or anisotropic liquids is shown to give readily interpretable information on molecular configurations, rates of motional processes, and intramolecular interactions. However, the observed intensity of high multiple-quantum transitions falls off dramatically as the number of coupled spins increases. The theory of multiple-quantum NMR is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first-order systems and anisotropic systems with high symmetry) to shown that this intensity decrease is expected if standard multiple-quantum pulse sequences are used. New pulse sequences are developed which excite coherences and produce population inversions only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible

Selectivity in multiple quantum nuclear magnetic resonance

Energy Technology Data Exchange (ETDEWEB)

Warren, Warren Sloan [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

1980-11-01

The observation of multiple-quantum nuclear magnetic resonance transitions in isotropic or anisotropic liquids is shown to give readily interpretable information on molecular configurations, rates of motional processes, and intramolecular interactions. However, the observed intensity of high multiple-quantum transitions falls off dramatically as the number of coupled spins increases. The theory of multiple-quantum NMR is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first-order systems and anisotropic systems with high symmetry) to shown that this intensity decrease is expected if standard multiple-quantum pulse sequences are used. New pulse sequences are developed which excite coherences and produce population inversions only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible.

Size dependent magnetism of mass selected deposited transition metal clusters

International Nuclear Information System (INIS)

Lau, T.

2002-05-01

The size dependent magnetic properties of small iron clusters deposited on ultrathin Ni/Cu(100) films have been studied with circularly polarised synchrotron radiation. For X-ray magnetic circular dichroism studies, the magnetic moments of size selected clusters were aligned perpendicular to the sample surface. Exchange coupling of the clusters to the ultrathin Ni/Cu(100) film determines the orientation of their magnetic moments. All clusters are coupled ferromagnetically to the underlayer. With the use of sum rules, orbital and spin magnetic moments as well as their ratios have been extracted from X-ray magnetic circular dichroism spectra. The ratio of orbital to spin magnetic moments varies considerably as a function of cluster size, reflecting the dependence of magnetic properties on cluster size and geometry. These variations can be explained in terms of a strongly size dependent orbital moment. Both orbital and spin magnetic moments are significantly enhanced in small clusters as compared to bulk iron, although this effect is more pronounced for the spin moment. Magnetic properties of deposited clusters are governed by the interplay of cluster specific properties on the one hand and cluster-substrate interactions on the other hand. Size dependent variations of magnetic moments are modified upon contact with the substrate. (orig.)

Dynamic analysis of magnetic nanoparticles crossing cell membrane

Energy Technology Data Exchange (ETDEWEB)

Pedram, Maysam Z. [Department of Mechanical Engineering, Sharif University of Tech., Azadi Ave., Tehran (Iran, Islamic Republic of); Shamloo, Amir, E-mail: shamloo@sharif.edu [Department of Mechanical Engineering, Sharif University of Tech., Azadi Ave., Tehran (Iran, Islamic Republic of); Ghafar-Zadeh, Ebrahim [Biologically-Inspired Sensors and Actuators Laboratory, Department of Electrical Engineering and Computer science, York University, Keel Street, Toronto (Canada); Alasty, Aria, E-mail: aalasti@sharif.edu [Department of Mechanical Engineering, Sharif University of Tech., Azadi Ave., Tehran (Iran, Islamic Republic of)

2017-05-01

Nowadays, nanoparticles (NPs) are used in a variety of biomedical applications including brain disease diagnostics and subsequent treatments. Among the various types of NPs, magnetic nanoparticles (MNPs) have been implemented by many research groups for an array of life science applications. In this paper, we studied MNPs controlled delivery into the endothelial cells using a magnetic field. Dynamics equations of MNPs were defined in the continuous domain using control theory methods and were applied to crossing the cell membrane. This study, dedicated to clinical and biomedical research applications, offers a guideline for the generation of a magnetic field required for the delivery of MNPs.

Magnetic particle mixing with magnetic micro-convection for microfluidics

International Nuclear Information System (INIS)

Kitenbergs, Guntars; Erglis, Kaspars; Perzynski, Régine; Cēbers, Andrejs

2015-01-01

In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the miscible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele–Shaw cell. Subsequent image analysis both qualitatively and quantitatively reveals the high enhancement of mixing efficiency provided by this method. The mixing efficiency dependence on the magnetic field and the physical limits is discussed. A suitable model for a continuous-flow microfluidics setup for mixing with magnetic micro-convection is also proposed and justified with an experiment. In addition, possible applications in improving the speed of ferrohydrodynamic sorting and magnetic label or selected tracer mixing in lab on a chip systems are noted. - Highlights: • We study the magnetic micro-convection as a mixing method in microfluidics. • We show that the method enhances mixing with magnetic field squared dependency. • We propose a flow cell setup for mixing and justify it with a sample experiment. • The mixing method can be easily implemented in an existing microfluidics setup

¹⁹F magnetic resonance probes for live-cell detection of peroxynitrite using an oxidative decarbonylation reaction.

Science.gov (United States)

Bruemmer, Kevin J; Merrikhihaghi, Sara; Lollar, Christina T; Morris, Siti Nur Sarah; Bauer, Johannes H; Lippert, Alexander R

2014-10-21

We report a newly discovered oxidative decarbonylation reaction of isatins that is selectively mediated by peroxynitrite (ONOO(-)) to provide anthranilic acid derivatives. We have harnessed this rapid and selective transformation to develop two reaction-based probes, 5-fluoroisatin and 6-fluoroisatin, for the low-background readout of ONOO(-) using (19)F magnetic resonance spectroscopy. 5-fluoroisatin was used to non-invasively detect ONOO(-) formation in living lung epithelial cells stimulated with interferon-γ (IFN-γ).

Manifestation of Spin Selection Rules on the Quantum Tunneling of Magnetization in a Single Molecule Magnet

OpenAIRE

Henderson, J. J.; Koo, C.; Feng, P. L.; del Barco, E.; Hill, S.; Tupitsyn, I. S.; Stamp, P. C. E.; Hendrickson, D. N.

2009-01-01

We present low temperature magnetometry measurements on a new Mn3 single-molecule magnet (SMM) in which the quantum tunneling of magnetization (QTM) displays clear evidence for quantum mechanical selection rules. A QTM resonance appearing only at elevated temperatures demonstrates tunneling between excited states with spin projections differing by a multiple of three: this is dictated by the C3 symmetry of the molecule, which forbids pure tunneling from the lowest metastable state. Resonances...

Instant magnetic labeling of tumor cells by ultrasound in vitro

International Nuclear Information System (INIS)

Mo Runyang; Yang Jian; Wu, Ed X.; Lin Shuyu

2011-01-01

Magnetic labeling of living cells creates opportunities for numerous biomedical applications. Here we describe an instantly cell magnetic labeling method based on ultrasound. We present a detailed study on the ultrasound performance of a simple and efficient labeling protocol for H-22 cells in vitro. High frequency focus ultrasound was investigated as an alternative method to achieve instant cell labeling with the magnetic particles without the need for adjunct agents or initiating cell cultures. Mean diameter of 168 nm dextran-T40 coated superparamagnetic iron oxide (SPIO) nanoparticles were prepared by means of classical coprecipitation in solution in our laboratory. H-22 tumor cells suspended in phosphate-buffered saline (PBS, pH=7.2) were exposed to ultrasound at 1.37 MHz for up to 120 s in the presence of SPIOs. The cellular uptake of iron oxide nanoparticles was detected by prussion blue staining. The viability of cells was determined by a trypan blue exclusion test. At 2 W power and 60 s ultrasound exposure in presence of 410 μg/ml SPIOs, H-22 cell labeling efficiency reached 69.4±6.3% and the labeled cells exhibited an iron content of 10.38±2.43 pg per cell. Furthermore, 95.2±3.2% cells remained viable. The results indicated that the ultrasound protocol could be potentially applied to label cells with large-sized magnetic particles. We also calculated the shear stress at the 2 W power and 1.37 MHz used in experiments. The results showed that the shear stress threshold for ultrasonically induced H-22 cell reparable sonoporation was 697 Pa. These findings provide a quantitative guidance in designing ultrasound protocols for cell labeling. - Highlights: → High frequency focus ultrasound can be used as a safe method for instant magnetic labeling of cells. → 8-16 times increased efficiency can be gained by ultrasound versus that by transfection agents. → Calculation of shear stress around cells provide a quantitative design for ultrasound protocols.

An effective strategy of magnetic stem cell delivery for spinal cord injury therapy

Science.gov (United States)

Tukmachev, Dmitry; Lunov, Oleg; Zablotskii, Vitalii; Dejneka, Alexandr; Babic, Michal; Syková, Eva; Kubinová, Šárka

2015-02-01

Spinal cord injury (SCI) is a condition that results in significant mortality and morbidity. Treatment of SCI utilizing stem cell transplantation represents a promising therapy. However, current conventional treatments are limited by inefficient delivery strategies of cells into the injured tissue. In this study, we designed a magnetic system and used it to accumulate stem cells labelled with superparamagnetic iron oxide nanoparticles (SPION) at a specific site of a SCI lesion. The loading of stem cells with engineered SPIONs that guarantees sufficient attractive magnetic forces was achieved. Further, the magnetic system allowed rapid guidance of the SPION-labelled cells precisely to the lesion location. Histological analysis of cell distribution throughout the cerebrospinal channel showed a good correlation with the calculated distribution of magnetic forces exerted onto the transplanted cells. The results suggest that focused targeting and fast delivery of stem cells can be achieved using the proposed non-invasive magnetic system. With future implementation the proposed targeting and delivery strategy bears advantages for the treatment of disease requiring fast stem cell transplantation.Spinal cord injury (SCI) is a condition that results in significant mortality and morbidity. Treatment of SCI utilizing stem cell transplantation represents a promising therapy. However, current conventional treatments are limited by inefficient delivery strategies of cells into the injured tissue. In this study, we designed a magnetic system and used it to accumulate stem cells labelled with superparamagnetic iron oxide nanoparticles (SPION) at a specific site of a SCI lesion. The loading of stem cells with engineered SPIONs that guarantees sufficient attractive magnetic forces was achieved. Further, the magnetic system allowed rapid guidance of the SPION-labelled cells precisely to the lesion location. Histological analysis of cell distribution throughout the cerebrospinal

Effects of high-gradient magnetic fields on living cell machinery

Czech Academy of Sciences Publication Activity Database

Zablotskyy, Vitaliy A.; Lunov, Oleg; Kubinová, Šárka; Polyakova, Tetyana; Syková, E.; Dejneka, Alexandr

2016-01-01

Roč. 49, č. 49 (2016), s. 1-23, č. článku 493003. ISSN 0022-3727 R&D Projects: GA MŠk LO1409 Grant - others:FUNBIO(XE) CZ.2.16/3.1.00/21568 Institutional support: RVO:68378271 Keywords : living cell * magnetic gradient force * cell mechanics * stem cell * magnetic field Subject RIV: BO - Biophysics Impact factor: 2.588, year: 2016

Addressing of LnCaP Cell Using Magnetic Particles Assisted Impedimetric Microelectrode.

Science.gov (United States)

Nguyen, Dung Thi Xuan; Tran, Trong Binh; Nguyen, Phuong-Diem; Min, Junhong

2016-03-01

In this study, we provide a facile, effective technique for a simple isolation and enrichment of low metastatic prostate tumor cell LNCaP using biocompatible, magnetic particles asissted impedimetric sensing system. Hydrophobic cell membrane anchors (BAM) were generated onto magnetic particles which diameters vary from 50 nm to 5 μm and were used to capture LNCaP cells from the suspension. Finally, magnetic particle-LNCaP complex were addressed onto the surface of the interdigitated microelectrode (IDM). Cell viability was monitored by our laboratory developed-technique Electrical Cell Substrate Impedance Sensing (ECIS). The results reavealed that 50 nm-magnetic particles showed best performance in terms of cell separation and cell viability. This technique provides a simple and efficient method for the direct addressing of LNCaP cell on the surface and enhances better understanding of cell behavior for cancer management in the near future.

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

Manifestation of spin selection rules on the quantum tunneling of magnetization in a single-molecule magnet.

Science.gov (United States)

Henderson, J J; Koo, C; Feng, P L; del Barco, E; Hill, S; Tupitsyn, I S; Stamp, P C E; Hendrickson, D N

2009-07-03

We present low temperature magnetometry measurements on a new Mn3 single-molecule magnet in which the quantum tunneling of magnetization (QTM) displays clear evidence for quantum mechanical selection rules. A QTM resonance appearing only at high temperatures demonstrates tunneling between excited states with spin projections differing by a multiple of three. This is dictated by the C3 molecular symmetry, which forbids pure tunneling from the lowest metastable state. Transverse field resonances are understood by correctly orienting the Jahn-Teller axes of the individual manganese ions and including transverse dipolar fields. These factors are likely to be important for QTM in all single-molecule magnets.

Magnetic Studies of Ferrofluid-Modified Microbial Cells

Czech Academy of Sciences Publication Activity Database

Mosiniewicz-Szablewska, E.; Šafaříková, Miroslava; Šafařík, Ivo

2010-01-01

Roč. 10, č. 4 (2010), s. 2531-2536 ISSN 1533-4880 R&D Projects: GA MPO(CZ) 2A-1TP1/094; GA MŠk(CZ) OC 108 Institutional research plan: CEZ:AV0Z60870520 Keywords : magnetically labeled cells * biocomposite materials * magnetic adsorbents Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.351, year: 2010

Magnetic catechin-dextran conjugate as targeted therapeutic for pancreatic tumour cells.

Science.gov (United States)

Vittorio, Orazio; Voliani, Valerio; Faraci, Paolo; Karmakar, Biswajit; Iemma, Francesca; Hampel, Silke; Kavallaris, Maria; Cirillo, Giuseppe

2014-06-01

Catechin-dextran conjugates have recently attracted a lot of attention due to their anticancer activity against a range of cancer cells. Magnetic nanoparticles have the ability to concentrate therapeutically important drugs due to their magnetic-spatial control and provide opportunities for targeted drug delivery. Enhancement of the anticancer efficiency of catechin-dextran conjugate by functionalisation with magnetic iron oxide nanoparticles. Modification of the coating shell of commercial magnetic nanoparticles (Endorem) composed of dextran with the catechin-dextran conjugate. Catechin-dextran conjugated with Endorem (Endo-Cat) increased the intracellular concentration of the drug and it induced apoptosis in 98% of pancreatic tumour cells placed under magnetic field. The conjugation of catechin-dextran with Endorem enhances the anticancer activity of this drug and provides a new strategy for targeted drug delivery on tumour cells driven by magnetic field. The ability to spatially control the delivery of the catechin-dextran by magnetic field makes it a promising agent for further application in cancer therapy.

Synthesis of magnetic microtubes decorated with nanowires and cells

Science.gov (United States)

Pomar, C. Diaz; Martinho, H.; Ferreira, F. F.; Goia, T. S.; Rodas, A. C. D.; Santos, S. F.; Souza, J. A.

2018-04-01

Antiferromagnetic and ferrimagnetic microtubes decorated with nanowires have been obtained during thermal oxidation process, which was assisted by in situ electrical resistivity measurements. The synthesis route including heat treatment and electrical current along with growth mechanism are presented. This simple method and the ability to tune in the magnetic moment of the obtained microtubes going from a nonmagnetic-like to a large magnetization saturation open an avenue for interesting applications. In vitro experiments involving adherence, migration, and proliferation of fibroblasts cell culture on the surface of the microtubes indicated the absence of cytotoxicity for this material. We have also calculated both torque and driving magnetic force for these microtubes with nanowires and cells as a function of external magnetic field gradient which were found to be robust opening the possibility for magnetic bio micro-robot device fabrication and application in biotechnology.

Selective Magnetic Removal of Pb(II from Aqueous Solution by Porphyrin Linked-Magnetic Nanoparticles

Directory of Open Access Journals (Sweden)

H. Ghanbarnejad

2012-12-01

Full Text Available The discharge of lead containing effluents into the environment and water bodies is harmful for the human, animals, aquatic flora and fauna. Herein, a novel surface engineered magnetic nanoparticle for removing Pb2+  ions was studied. After surface modification of the magnetite by 3-amino-propyltriethoxysilane (APTES magnetic nanoparticles with covalently linked porphyrins were synthesized. Two atropisomers of  meso-tetrakis(2-carboxy-4-nonylphenyl porphyrin (TCNP were tested to analyze the atropisomeric effect on lead uptake. For characterize the synthesized nanosorbents methods like: Transform Infrared Spectroscopy, X-ray diffraction, Transmission Electron Microscopy and Thermo-Gravimetric Analysis were used. The effects of pH, contact time, sorbent dosage and some co-existing cations were investigated. Regeneration of lead adsorbed material could be possible and the modified magnetic nanoparticles exhibited good reusability. The use of such a system can provide fast and efficient removal of the lead ion by using an external magnetic field. The competitive adsorption tests showed good adsorption selectivity for lead ion.

Optimization of magnetic switches for single particle and cell transport

Energy Technology Data Exchange (ETDEWEB)

Abedini-Nassab, Roozbeh; Yellen, Benjamin B., E-mail: yellen@duke.edu [Department of Mechanical Engineering and Materials Science, Duke University, Box 90300 Hudson Hall, Durham, North Carolina 27708 (United States); Joint Institute, University of Michigan—Shanghai Jiao Tong University, Shanghai Jiao Tong University, Shanghai 200240 (China); Murdoch, David M. [Department of Medicine, Duke University, Durham, North Carolina 27708 (United States); Kim, CheolGi [Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873 (Korea, Republic of)

2014-06-28

The ability to manipulate an ensemble of single particles and cells is a key aim of lab-on-a-chip research; however, the control mechanisms must be optimized for minimal power consumption to enable future large-scale implementation. Recently, we demonstrated a matter transport platform, which uses overlaid patterns of magnetic films and metallic current lines to control magnetic particles and magnetic-nanoparticle-labeled cells; however, we have made no prior attempts to optimize the device geometry and power consumption. Here, we provide an optimization analysis of particle-switching devices based on stochastic variation in the particle's size and magnetic content. These results are immediately applicable to the design of robust, multiplexed platforms capable of transporting, sorting, and storing single cells in large arrays with low power and high efficiency.

Solid-State NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization

International Nuclear Information System (INIS)

Takahashi, Hiroki; Bardet, Michel; De Paepe, Gael; Hediger, Sabine; Ayala, Isabel; Simorre, Jean-Pierre

2013-01-01

Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool. (authors)

Solid-state NMR on bacterial cells: selective cell wall signal enhancement and resolution improvement using dynamic nuclear polarization.

Science.gov (United States)

Takahashi, Hiroki; Ayala, Isabel; Bardet, Michel; De Paëpe, Gaël; Simorre, Jean-Pierre; Hediger, Sabine

2013-04-03

Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) has recently emerged as a powerful technique for the study of material surfaces. In this study, we demonstrate its potential to investigate cell surface in intact cells. Using Bacillus subtilis bacterial cells as an example, it is shown that the polarizing agent 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL) has a strong binding affinity to cell wall polymers (peptidoglycan). This particular interaction is thoroughly investigated with a systematic study on extracted cell wall materials, disrupted cells, and entire cells, which proved that TOTAPOL is mainly accumulating in the cell wall. This property is used on one hand to selectively enhance or suppress cell wall signals by controlling radical concentrations and on the other hand to improve spectral resolution by means of a difference spectrum. Comparing DNP-enhanced and conventional solid-state NMR, an absolute sensitivity ratio of 24 was obtained on the entire cell sample. This important increase in sensitivity together with the possibility of enhancing specifically cell wall signals and improving resolution really opens new avenues for the use of DNP-enhanced solid-state NMR as an on-cell investigation tool.

Selection of planes in nuclear magnetic resonance tomography

International Nuclear Information System (INIS)

Bonagamba, T.J.

1986-01-01

A prototype aiming to obtain images in nuclear magnetic resonance tomography was developed, by adjusting NMR spectrometer in the IFQSC Laboratory. The techniques for selecting planes were analysed by a set of computer codes, which were elaborated from Bloch equation solutions to simulate the spin system behaviour. Images were obtained using planes with thickness inferior to 1 cm. (M.C.K.)

Pulsed taut-wire measurement of the magnetic alignment of the ITS induction cells

International Nuclear Information System (INIS)

Melton, J.G.; Burns, M.J.; Honaberger, D.J.

1993-01-01

The mechanical and magnetic alignment of the first eight induction-cell, solenoid magnets of the Integrated Test Stand (ITS) for the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility were measured by observing the deflection of a fine, taut wire carrying a pulsed current. To achieve the required alignment (less than 0.25 mm offset and less than 5 mrad tilt), the magnet design uses quadrufilar windings and iron field-smoothing rings. After detailed measurements of each solenoid magnet, the cells are assembled and then mechanically aligned using a laser and an alignment target moved along the cell centerline. After the cells are in final position, the pulsed wire method is used to verify the magnetic alignment. The measurements show an average offset of the magnetic axes from the mechanical axis of 0. 15 mm, with a maximum offset of 0.3 mm. The average tilt of the magnetic axis was 0.7 mrad with a maximum tilt of 1.4 mrad. Tilts are corrected to less than 0.3 mrad, using dipole trim magnets assembled into each cell. Correction is limited noise

Disruptive effect of Dzyaloshinskii-Moriya interaction on the magnetic memory cell performance

Energy Technology Data Exchange (ETDEWEB)

Sampaio, J.; Cubukcu, M.; Cros, V.; Reyren, N., E-mail: nicolas.reyren@thalesgroup.com [Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau (France); Khvalkovskiy, A. V. [Samsung Electronics, Semiconductor R& D Center (Grandis), San Jose, California 95134 (United States); Moscow Institute of Physics and Technology, State University, Moscow 141700 (Russian Federation); Kuteifan, M.; Lomakin, V. [Department of Electrical and Computer Engineering, University of California at San Diego, La Jolla, California 92093-0407 (United States); Apalkov, D. [Samsung Electronics, Semiconductor R& D Center (Grandis), San Jose, California 95134 (United States)

2016-03-14

In order to increase the thermal stability of a magnetic random access memory cell, materials with high spin-orbit interaction are often introduced in the storage layer. As a side effect, a strong Dzyaloshinskii-Moriya interaction (DMI) may arise in such systems. Here, we investigate the impact of DMI on the magnetic cell performance, using micromagnetic simulations. We find that DMI strongly promotes non-uniform magnetization states and non-uniform switching modes of the magnetic layer. It appears to be detrimental for both the thermal stability of the cell and its switching current, leading to considerable deterioration of the cell performance even for a moderate DMI amplitude.

Selective extraction of bisphenol A from water by one-monomer molecularly imprinted magnetic nanoparticles.

Science.gov (United States)

Lin, Zhenkun; Zhang, Yanfang; Su, Yu; Qi, Jinxia; Jia, Yinhang; Huang, Changjiang; Dong, Qiaoxiang

2018-01-15

One-monomer molecularly imprinted magnetic nanoparticles were prepared as adsorbents for selective extraction of bisphenol A from water in this study. A single bi-functional monomer was adopted for preparation of the molecularly imprinted polymer, avoiding the tedious trial-and-error optimizations as traditional strategy. Moreover, bisphenol F was used as the dummy template for bisphenol A to avoid the interference from residual template molecules. These nanoparticles showed not only large adsorption capacity and good selectivity to the bisphenol A but also outstanding magnetic response performance. Furthermore, they were successfully used as magnetic solid-phase extraction adsorbents of bisphenol A from various water samples, including tap water, river water, and seawater. The developed method was found to be much more efficient, convenient, and economical for selective extraction of bisphenol A compared with the traditional solid-phase extraction. Separation of these nanoparticles can be easily achieved with an external magnetic field, and the optimized adsorption time was only 15 min. The recoveries of bisphenol A in different water samples ranged from 85.38 to 93.75%, with relative standard deviation lower than 7.47%. These results showed that one-monomer molecularly imprinted magnetic nanoparticles had the potential to be popular adsorbents for selective extraction of pollutants from water. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clinically viable magnetic poly(lactide-co-glycolide) (PLGA) particles for MRI-based cell tracking

Science.gov (United States)

Granot, Dorit; Nkansah, Michael K.; Bennewitz, Margaret F.; Tang, Kevin S.; Markakis, Eleni A.; Shapiro, Erik M.

2013-01-01

Purpose To design, fabricate, characterize and in vivo assay clinically viable magnetic particles for MRI-based cell tracking. Methods PLGA encapsulated magnetic nano- and microparticles were fabricated. Multiple biologically relevant experiments were performed to assess cell viability, cellular performance and stem cell differentiation. In vivo MRI experiments were performed to separately test cell transplantation and cell migration paradigms, as well as in vivo biodegradation. Results Highly magnetic nano- (~100 nm) and microparticles (~1–2 μm) were fabricated. Magnetic cell labeling in culture occurred rapidly achieving 3–50 pg Fe/cell at 3 hrs for different particles types, and >100 pg Fe/cell after 10 hours, without the requirement of a transfection agent, and with no effect on cell viability. The capability of magnetically labeled mesenchymal or neural stem cells to differentiate down multiple lineages, or for magnetically labeled immune cells to release cytokines following stimulation, was uncompromised. An in vivo biodegradation study revealed that NPs degraded ~80% over the course of 12 weeks. MRI detected as few as 10 magnetically labeled cells, transplanted into the brains of rats. Also, these particles enabled the in vivo monitoring of endogenous neural progenitor cell migration in rat brains over 2 weeks. Conclusion The robust MRI properties and benign safety profile of these particles make them promising candidates for clinical translation for MRI-based cell tracking. PMID:23568825

Detecting molecules and cells labeled with magnetic particles using an atomic magnetometer

International Nuclear Information System (INIS)

Yu Dindi; Ruangchaithaweesuk, Songtham; Yao Li; Xu Shoujun

2012-01-01

The detection of magnetically labeled molecules and cells involves three essential parameters: sensitivity, spatial resolution, and molecular specificity. We report on the use of atomic magnetometry and its derivative techniques to achieve high performance in terms of all these parameters. With a sensitivity of 80 fT/√Hz for dc magnetic fields, we show that 7,000 streptavidin-conjugated magnetic microparticles magnetized by a permanent magnet produce a magnetic field of 650 pT; this result predicts that a single such particle can be detected during one second of signal averaging. Spatial information is obtained using a scanning magnetic imaging scheme. The spatial resolution is 20 μm with a detection distance of more than 1 cm; this distance is much longer than that in previous reports. The molecular specificity is achieved using force-induced remnant magnetization spectroscopy, which currently uses an atomic magnetometer for detection. As an example, we perform measurement of magnetically labeled human CD4+ T cells, whose count in the blood is the diagnostic criterion for human immunodeficiency virus infection. Magnetic particles that are specifically bound to the cells are resolved from nonspecifically bound particles and quantitatively correlate with the number of cells. The magnetic particles have an overall size of 2.8 μm, with a magnetic core in nanometer regime. The combination of our techniques is predicted to be useful in molecular and cellular imaging.

Detecting molecules and cells labeled with magnetic particles using an atomic magnetometer

Energy Technology Data Exchange (ETDEWEB)

Yu Dindi; Ruangchaithaweesuk, Songtham; Yao Li; Xu Shoujun, E-mail: sxu7@uh.edu [University of Houston, Department of Chemistry (United States)

2012-09-15

The detection of magnetically labeled molecules and cells involves three essential parameters: sensitivity, spatial resolution, and molecular specificity. We report on the use of atomic magnetometry and its derivative techniques to achieve high performance in terms of all these parameters. With a sensitivity of 80 fT/{radical}Hz for dc magnetic fields, we show that 7,000 streptavidin-conjugated magnetic microparticles magnetized by a permanent magnet produce a magnetic field of 650 pT; this result predicts that a single such particle can be detected during one second of signal averaging. Spatial information is obtained using a scanning magnetic imaging scheme. The spatial resolution is 20 {mu}m with a detection distance of more than 1 cm; this distance is much longer than that in previous reports. The molecular specificity is achieved using force-induced remnant magnetization spectroscopy, which currently uses an atomic magnetometer for detection. As an example, we perform measurement of magnetically labeled human CD4+ T cells, whose count in the blood is the diagnostic criterion for human immunodeficiency virus infection. Magnetic particles that are specifically bound to the cells are resolved from nonspecifically bound particles and quantitatively correlate with the number of cells. The magnetic particles have an overall size of 2.8 {mu}m, with a magnetic core in nanometer regime. The combination of our techniques is predicted to be useful in molecular and cellular imaging.

Preparation of a magnetic molecularly imprinted polymer for selective recognition of rhodamine B

International Nuclear Information System (INIS)

Liu, Xiuying; Yu, Dan; Yu, Yingchao; Ji, Shujuan

2014-01-01

Graphical abstract: A novel material based on the use of magnetic Fe3O4 nanoparticles coated with MMIP for preconcentration and determination of RhB in real samples prior to fluorospectrophotometry was developed. - Highlights: • A novel rhodamine B magnetic molecularly imprinted polymer by using Fe 3 O 4 magnetite as the magnetically susceptible component was synthesized. • The MMIP had rapid adsorption and high selectivity towards rhodamine B. • Rhodamine B can be extracted selectively by MMIP from real samples. • The method provides the advantages of short analysis time and high sensitivity. - Abstract: A novel magnetic molecularly imprinted polymer (MMIP) was developed as an adsorbent to selectively remove rhodamine B from real samples. The polymer was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and thermo-gravimetric analysis. Static adsorption, kinetic adsorption, and selective recognition experiments were also performed to investigate the specific adsorption equilibrium, kinetics, and selective recognition ability of the MMIP. The MMIPs had outstanding thermal stability, large adsorption capacity, and high competitive selectivity. When they were used as dispersed solid-phase extraction adsorbents in real samples, rhodamine B recovery was 79.97–81.88% and 75.56–79.74% in intra-day and inter-day reproducibility experiments with relative standard deviations lower than 2.62% and 4.28%, respectively. Extraction was optimized for yield and efficiency. Precision, accuracy, and linear working range were determined under optimal experimental conditions. The limits of detection and quantification were 1.05 and 3.49 μg L −1 , respectively. These results suggest MMIPs may be used for determination of rhodamine B in real samples

Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

NARCIS (Netherlands)

Venkatesan, P.; Vander Hoogerstraete, Tom; Hennebel, Tom; Binnemans, Koen; Sietsma, J.; Yang, Y.

2018-01-01

NdFeB magnet waste is one of the important secondary resources from which rare-earth elements (REEs) can be recovered. Herein we present an electrochemical route to selectively extract REEs from the magnet waste at room temperature. First, the magnet waste was partially leached with HCl. The

Erythrocyte enrichment in hematopoietic progenitor cell cultures based on magnetic susceptibility of the hemoglobin.

Directory of Open Access Journals (Sweden)

Xiaoxia Jin

Full Text Available Using novel media formulations, it has been demonstrated that human placenta and umbilical cord blood-derived CD34+ cells can be expanded and differentiated into erythroid cells with high efficiency. However, obtaining mature and functional erythrocytes from the immature cell cultures with high purity and in an efficient manner remains a significant challenge. A distinguishing feature of a reticulocyte and maturing erythrocyte is the increasing concentration of hemoglobin and decreasing cell volume that results in increased cell magnetophoretic mobility (MM when exposed to high magnetic fields and gradients, under anoxic conditions. Taking advantage of these initial observations, we studied a noninvasive (label-free magnetic separation and analysis process to enrich and identify cultured functional erythrocytes. In addition to the magnetic cell separation and cell motion analysis in the magnetic field, the cell cultures were characterized for cell sedimentation rate, cell volume distributions using differential interference microscopy, immunophenotyping (glycophorin A, hemoglobin concentration and shear-induced deformability (elongation index, EI, by ektacytometry to test for mature erythrocyte attributes. A commercial, packed column high-gradient magnetic separator (HGMS was used for magnetic separation. The magnetically enriched fraction comprised 80% of the maturing cells (predominantly reticulocytes that showed near 70% overlap of EI with the reference cord blood-derived RBC and over 50% overlap with the adult donor RBCs. The results demonstrate feasibility of label-free magnetic enrichment of erythrocyte fraction of CD34+ progenitor-derived cultures based on the presence of paramagnetic hemoglobin in the maturing erythrocytes.

Magnetically-focusing biochip structures for high-speed active biosensing with improved selectivity

Science.gov (United States)

Yoo, Haneul; Lee, Dong Jun; Kim, Daesan; Park, Juhun; Chen, Xing; Hong, Seunghun

2018-06-01

We report a magnetically-focusing biochip structure enabling a single layered magnetic trap-and-release cycle for biosensors with an improved detection speed and selectivity. Here, magnetic beads functionalized with specific receptor molecules were utilized to trap target molecules in a solution and transport actively to and away from the sensor surfaces to enhance the detection speed and reduce the non-specific bindings, respectively. Using our method, we demonstrated the high speed detection of IL-13 antigens with the improved detection speed by more than an order of magnitude. Furthermore, the release step in our method was found to reduce the non-specific bindings and improve the selectivity and sensitivity of biosensors. This method is a simple but powerful strategy and should open up various applications such as ultra-fast biosensors for point-of-care services.

Neuropsychology of selective attention and magnetic cortical stimulation.

Science.gov (United States)

Sabatino, M; Di Nuovo, S; Sardo, P; Abbate, C S; La Grutta, V

1996-01-01

Informed volunteers were asked to perform different neuropsychological tests involving selective attention under control conditions and during transcranial magnetic cortical stimulation. The tests chosen involved the recognition of a specific letter among different letters (verbal test) and the search for three different spatial orientations of an appendage to a square (visuo-spatial test). For each test the total time taken and the error rate were calculated. Results showed that cortical stimulation did not cause a worsening in performance. Moreover, magnetic stimulation of the temporal lobe neither modified completion time in both verbal and visuo-spatial tests nor changed error rate. In contrast, magnetic stimulation of the pre-frontal area induced a significant reduction in the performance time of both the verbal and visuo-spatial tests always without an increase in the number of errors. The experimental findings underline the importance of the pre-frontal area in performing tasks requiring a high level of controlled attention and suggest the need to adopt an interdisciplinary approach towards the study of neurone/mind interface mechanisms.

Rotational magnetic pulses enhance the magnetofection efficiency in vitro in adherent and suspension cells

International Nuclear Information System (INIS)

Dahmani, Ch.; Mykhaylyk, O.; Helling, Fl.; Götz, St.; Weyh, Th.; Herzog, H.-G.; Plank, Ch.

2013-01-01

The association of magnetic nanoparticles with gene delivery vectors in combination with the use of gradient magnetic fields (magnetofection) enables improved and synchronised gene delivery to cells. In this paper, we report a system comprising rotating permanent magnets to generate defined magnetic field pulses with frequencies from 2.66 to 133 Hz and a field amplitude of 190 or 310 mT at the location of the cells. Low-frequency pulses of 2.66–10 Hz with a magnetic flux density of 190 mT were applied to the examined cells for 30–120 s after magnetofection. These pulses resulted in a 1.5–1.9-fold enhancement in the transfection efficiency compared with magnetofection with only a static magnetic field in both adherent and suspension cells. The magnetic field amplitudes of 190 and 310 mT had similar effects on the transfection efficacy. No increase in the percentage of transgene-expressing suspension cells and no cytotoxic effects (based on the results of the MTT assay) were observed after applying alternating magnetic fields. - Highlights: ► We developed a magnetic system capable of generating defined magnetic pulses based on permanent magnets. ► The main advantage of the system is the lack of heat-induced fluctuations in the working parameters. ► Our system succeeded in enhancing the transfection of adherent human lung epithelial cells and human suspension cells. ► The enhancement in the transfection efficiency compared with static magnetic field is due to the magnetic field pulses. ► The approach could be used as a complementary method for drug targeting

Effect of plastic deformation on the magnetic properties of selected austenitic stainless steels

Directory of Open Access Journals (Sweden)

Tatiana Oršulová

2017-04-01

Full Text Available Austenitic stainless steels are materials, that are widely used in various fields of industry, architecture and biomedicine. Their specific composition of alloying elements has got influence on their deformation behavior. The main goal of this study was evaluation of magnetic properties of selected steels, caused by plastic deformation. The samples were heat treated in different intervals of temperature before measuring. Then the magnetic properties were measured on device designed for measuring of magnetism. From tested specimens, only AISI 304 confirmed effect of plastic deformation on the magnetic properties. Magnetic properties changed with increasing temperature.

Sorption of strontium by magnetically modified yeast cells

International Nuclear Information System (INIS)

Hu Yantao; Ji Yanqin; Tian Qing; Shao Xianzhang; Shi Jianhe; Ivo Safarik; Zhang Shengdong; Li Jinying

2008-01-01

Magnetically modified fodder's yeast (Kluyveromyces fragilis) cells using water based magnetic fluid, were characterized by scanning electron microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The sorption-desorption properties of Sr 2+ by these yeast cells from nitrate salt of Sr 2+ were studied. The results demonstrated that the Sr 2+ sorption volume by these cells enhanced with increasing pH and reached a plateau between pH 4.0 and 7.0. A minor effect by temperature was observed. The sorption volumes are 19.5 mg/g and 53.5 mg/g from 10 ppm and 40 ppm Sr 2+ solution respectively within 20 min. The sorption of Sr 2+ in these cells can be desorbed under 0.1 mol/L HNO 3 solution. The maximum Sr 2+ sorption volume is 96.7 mg/g at 20℃. The sorption characteristic fits Langmuir model well with 140.8 mg/g calculated maximum sorption volume by these yeast cells. (authors)

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.

Integration of carboxyl modified magnetic particles and aqueous two-phase extraction for selective separation of proteins.

Science.gov (United States)

Gai, Qingqing; Qu, Feng; Zhang, Tao; Zhang, Yukui

2011-07-15

Both of the magnetic particle adsorption and aqueous two-phase extraction (ATPE) were simple, fast and low-cost method for protein separation. Selective proteins adsorption by carboxyl modified magnetic particles was investigated according to protein isoelectric point, solution pH and ionic strength. Aqueous two-phase system of PEG/sulphate exhibited selective separation and extraction for proteins before and after magnetic adsorption. The two combination ways, magnetic adsorption followed by ATPE and ATPE followed by magnetic adsorption, for the separation of proteins mixture of lysozyme, bovine serum albumin, trypsin, cytochrome C and myloglobin were discussed and compared. The way of magnetic adsorption followed by ATPE was also applied to human serum separation. Copyright © 2011 Elsevier B.V. All rights reserved.

Pd nanoparticles encapsulated in magnetic carbon nanocages: an efficient nanoenzyme for the selective detection and multicolor imaging of cancer cells

Science.gov (United States)

Chen, Gaosong; Song, Jingjing; Zhang, Haoli; Jiang, Yuntian; Liu, Weisheng; Zhang, Wei; Wang, Baodui

2015-08-01

Rapid and simple molecular recognition based techniques for the identification of the subtypes of cancer cells are essential in molecular medicine. However, improving the sensitivity and accuracy of the early diagnosis of this disease remains a major challenge. Herein, we develop a novel approach for the in situ growth of palladium nanoparticles in magnetic carbon nanocages (PdNPs/MCNCs). The confined Pd NPs, which have excellent dispersion in magnetic carbon nanocages, show superior catalytic performance for the cleavage reaction of N-butyl-4-NHAlloc-1,8-naphthalimide (NNPH), thereby producing significant changes in both color (from colorless to jade-green) and fluorescence (from blue to green) through the ICT process. Based on the abovementioned results, a novel sensing platform utilizing the PdNPs/MCNC nanocatalyst as an artificial enzyme and NNPH as a fluorescent and color change reporter molecule for the multicolor imaging and colorimetric detection of cancer cells was developed. We envision that this nanomaterial can be used as a power tool for a wide range of potential applications in biotechnology and medicine.Rapid and simple molecular recognition based techniques for the identification of the subtypes of cancer cells are essential in molecular medicine. However, improving the sensitivity and accuracy of the early diagnosis of this disease remains a major challenge. Herein, we develop a novel approach for the in situ growth of palladium nanoparticles in magnetic carbon nanocages (PdNPs/MCNCs). The confined Pd NPs, which have excellent dispersion in magnetic carbon nanocages, show superior catalytic performance for the cleavage reaction of N-butyl-4-NHAlloc-1,8-naphthalimide (NNPH), thereby producing significant changes in both color (from colorless to jade-green) and fluorescence (from blue to green) through the ICT process. Based on the abovementioned results, a novel sensing platform utilizing the PdNPs/MCNC nanocatalyst as an artificial enzyme and NNPH

The Use of Gadolinium-Carbon Nanostructures to Magnetically Enhance Stem Cell Retention for Cellular Cardiomyoplasty

Science.gov (United States)

Tran, Lesa A.; Hernández-Rivera, Mayra; Berlin, Ari N.; Zheng, Yi; Sampaio, Luiz; Bové, Christina; Cabreira-Hansen, Maria da Graça; Willerson, James T.; Perin, Emerson C.; Wilson, Lon J.

2014-01-01

In this work, the effectiveness of using Gadonanotubes (GNTs) with an external magnetic field to improve retention of transplanted adult mesenchymal stem cells (MSCs) during cellular cardiomyoplasty was evaluated. As a high-performance T1-weighted magnetic resonance imaging (MRI) cell tracking label, the GNTs are gadolinium-loaded carbon nanotube capsules that render MSCs magnetic when internalized. MSCs were internally labeled with either superparamagnetic GNTs or colloidal diamagnetic lutetium (Lu). In vitro cell rolling assays and ex vivo cardiac perfusion experiments qualitatively demonstrated increased magnetic-assisted retention of GNT-labeled MSCs. Subsequent in vivo epicardial cell injections were performed around a 1.3 T NdFeB ring magnet sutured onto the left ventricle of female juvenile pigs (n = 21). Cell dosage, magnet exposure time, and endpoints were varied to evaluate the safety and efficacy of the proposed therapy. Quantification of retained cells in collected tissues by elemental analysis (Gd or Lu) showed that the external magnet helped retain nearly three times more GNT-labeled MSCs than Lu-labeled cells. The sutured magnet was tolerated for up to 168 hours; however, an inflammatory response to the magnet was noted after 48 hours. These proof-of-concept studies support the feasibility and value of using GNTs as a magnetic nanoparticle facilitator to improve cell retention during cellular cardiomyoplasty. PMID:24148239

The use of gadolinium-carbon nanostructures to magnetically enhance stem cell retention for cellular cardiomyoplasty.

Science.gov (United States)

Tran, Lesa A; Hernández-Rivera, Mayra; Berlin, Ari N; Zheng, Yi; Sampaio, Luiz; Bové, Christina; Cabreira-Hansen, Maria da Graça; Willerson, James T; Perin, Emerson C; Wilson, Lon J

2014-01-01

In this work, the effectiveness of using Gadonanotubes (GNTs) with an external magnetic field to improve retention of transplanted adult mesenchymal stem cells (MSCs) during cellular cardiomyoplasty was evaluated. As a high-performance T1-weighted magnetic resonance imaging (MRI) cell tracking label, the GNTs are gadolinium-loaded carbon nanotube capsules that render MSCs magnetic when internalized. MSCs were internally labeled with either superparamagnetic GNTs or colloidal diamagnetic lutetium (Lu). In vitro cell rolling assays and ex vivo cardiac perfusion experiments qualitatively demonstrated increased magnetic-assisted retention of GNT-labeled MSCs. Subsequent in vivo epicardial cell injections were performed around a 1.3 T NdFeB ring magnet sutured onto the left ventricle of female juvenile pigs (n = 21). Cell dosage, magnet exposure time, and endpoints were varied to evaluate the safety and efficacy of the proposed therapy. Quantification of retained cells in collected tissues by elemental analysis (Gd or Lu) showed that the external magnet helped retain nearly three times more GNT-labeled MSCs than Lu-labeled cells. The sutured magnet was tolerated for up to 168 h; however, an inflammatory response to the magnet was noted after 48 h. These proof-of-concept studies support the feasibility and value of using GNTs as a magnetic nanoparticle facilitator to improve cell retention during cellular cardiomyoplasty. Copyright © 2013 Elsevier Ltd. All rights reserved.

Technical Note: Response measurement for select radiation detectors in magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Reynolds, M., E-mail: michaelreynolds@ualberta.net [Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Fallone, B. G. [Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada and Departments of Oncology and Physics, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Rathee, S. [Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, Medical Physics Division,University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada)

2015-06-15

Purpose: Dose response to applied magnetic fields for ion chambers and solid state detectors has been investigated previously for the anticipated use in linear accelerator–magnetic resonance devices. In this investigation, the authors present the measured response of selected radiation detectors when the magnetic field is applied in the same direction as the radiation beam, i.e., a longitudinal magnetic field, to verify previous simulation only data. Methods: The dose response of a PR06C ion chamber, PTW60003 diamond detector, and IBA PFD diode detector is measured in a longitudinal magnetic field. The detectors are irradiated with buildup caps and their long axes either parallel or perpendicular to the incident photon beam. In each case, the magnetic field dose response is reported as the ratio of detector signals with to that without an applied longitudinal magnetic field. The magnetic field dose response for each unique orientation as a function of magnetic field strength was then compared to the previous simulation only studies. Results: The measured dose response of each detector in longitudinal magnetic fields shows no discernable response up to near 0.21 T. This result was expected and matches the previously published simulation only results, showing no appreciable dose response with magnetic field. Conclusions: Low field longitudinal magnetic fields have been shown to have little or no effect on the dose response of the detectors investigated and further lend credibility to previous simulation only studies.

[Synergetic killing effects of external magnetic fields combined with porphyrin-dextran magnetic nanoparticles on the human bladder cancer cells].

Science.gov (United States)

Luo, Dao-sheng; Mi, Qi-wu; Meng, Xiang-jun; Gao, Yong; Dai, Yu-ping; Deng, Chun-hua

2012-08-18

To study the synergetic killing effects of external magnetic fields combined with the photodynamic action of porphyrin-dextran iron oxide magnetic nanoparticles (PDMN) on human bladder cancer cells in vitro. The PDMN were produced by using the chemical co-precipitation and redox process and the physicochemical properties were characterized. Methyl thiazolyl tetrazolium (MTT) and flow cytometry were used to determine the effects of photodynamic therapy of PDMN combined with external pulsed electromagnetic fields (5 mT) on killing human bladder cancer BIU-87 cells respectively. The diameters of PDMN were 10-15 nm and the saturation magnetization was 0.20 emu/g. Effective diameter of PDMN was 94.8 nm. PDMN could remarkably inhibit the proliferation and induce the obvious apoptosis of BIU-87 cells, and the rates of growth inhibition and apoptosis were (17.61±2.73)% and (24.53±5.74)% respectively. Moreover, external pulsed electromagnetic fields (5 mT) could also suppress the proliferation and induce apoptosis of BIU-87 cells. Furthermore, the photodynamic action of PDMN combined with external magnetic fields significantly inhibited the proliferation and promote apoptosis of BIU-87 cells, and the rates of growth inhibition and apoptosis was (28.11±4.25)% and (24.53±5.74)%, respectively, which were significantly higher than those of other groups (Peffectively inhibit proliferation and induce apoptosis of BIU-87 cells. Moreover, these effects on BIU-87 cells could be strengthened by the combination with external magnetic fields.

Magnetic cell sorting purification of differentiated embryonic stem cells stably expressing truncated human CD4 as surface marker.

Science.gov (United States)

David, Robert; Groebner, Michael; Franz, Wolfgang-Michael

2005-04-01

Embryonic stem (ES) cells offer great potential in regenerative medicine and tissue engineering. Clinical applications are still hampered by the lack of protocols for gentle, high-yield isolation of specific cell types for transplantation expressing no immunogenic markers. We describe labeling of stably transfected ES cells expressing a human CD4 molecule lacking its intracellular domain (DeltaCD4) under control of the phosphoglycerate kinase promoter for magnetic cell sorting (MACS). To track the labeled ES cells, we fused DeltaCD4 to an intracellular enhanced green fluorescent protein domain (DeltaCD4EGFP). We showed functionality of the membrane-bound fluorescent fusion protein and its suitability for MACS leading to purities greater than 97%. Likewise, expression of DeltaCD4 yielded up to 98.5% positive cells independently of their differentiation state. Purities were not limited by the initial percentage of DeltaCD4(+) cells, ranging from 0.6%-16%. The viability of MACS-selected cells was demonstrated by reaggregation and de novo formation of embryoid bodies developing all three germ layers. Thus, expression of DeltaCD4 in differentiated ES cells may enable rapid, high-yield purification of a desired cell type for tissue engineering and transplantation studies.

Necrosis of HepG2 cancer cells induced by the vibration of magnetic particles

Energy Technology Data Exchange (ETDEWEB)

Wang, Biran [Laboratoire de Physique de la Matière Condensée (LPMC), CNRS UMR 7336, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice (France); Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Bienvenu, Céline [Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Mendez-Garza, Juan; Lançon, Pascal; Madeira, Alexandra [Laboratoire de Physique de la Matière Condensée (LPMC), CNRS UMR 7336, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice (France); Vierling, Pierre [Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Di Giorgio, Christophe, E-mail: christophe.di-giorgio@unice.fr [Institut de Chimie de Nice, UMR 7272, Université de Nice Sophia Antipolis, CNRS, 28 Avenue de Valrose, F-06100 Nice (France); Bossis, Georges, E-mail: bossis@unice.fr [Laboratoire de Physique de la Matière Condensée (LPMC), CNRS UMR 7336, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice (France)

2013-10-15

Experiments of magnetolysis, i.e., destruction of cells induced with magnetic particles (MPs) submitted to the application of a magnetic field, were conducted on HepG2 cancer cells. We herein demonstrate the usefulness of combining anisotropic MPs with an alternative magnetic field in magnetolysis. Thus, the application of an alternative magnetic field of low frequency (a few Hertz) in the presence of anisotropic, submicronic particles allowed the destruction of cancer cells “in vitro”. We also show that a constant magnetic field is far less efficient than an oscillating one. Moreover, we demonstrate that, at equal particle volume, it is much more efficient to utilize spindle shaped particles rather than spherical ones. In order to get deeper insight into the mechanism of magnetolysis experiments, we performed a study by AFM, which strongly supports that the magnetic field induces the formation of clusters of particles becoming then large enough todamage cell membranes. - Highlights: • Magnetic force was applied on cancer cells through magnetic particles. • The penetration depth was predicted, both for spherical and ellipsoidal particles. • Alternative force was shown to damage the cells contrary to static force. • The effect of indentation of magnetic particles was compared to the one of AFM tips. • The damage was attributed to the formation of clusters of particles.

Magnetic assembly of 3D cell clusters: visualizing the formation of an engineered tissue.

Science.gov (United States)

Ghosh, S; Kumar, S R P; Puri, I K; Elankumaran, S

2016-02-01

Contactless magnetic assembly of cells into 3D clusters has been proposed as a novel means for 3D tissue culture that eliminates the need for artificial scaffolds. However, thus far its efficacy has only been studied by comparing expression levels of generic proteins. Here, it has been evaluated by visualizing the evolution of cell clusters assembled by magnetic forces, to examine their resemblance to in vivo tissues. Cells were labeled with magnetic nanoparticles, then assembled into 3D clusters using magnetic force. Scanning electron microscopy was used to image intercellular interactions and morphological features of the clusters. When cells were held together by magnetic forces for a single day, they formed intercellular contacts through extracellular fibers. These kept the clusters intact once the magnetic forces were removed, thus serving the primary function of scaffolds. The cells self-organized into constructs consistent with the corresponding tissues in vivo. Epithelial cells formed sheets while fibroblasts formed spheroids and exhibited position-dependent morphological heterogeneity. Cells on the periphery of a cluster were flattened while those within were spheroidal, a well-known characteristic of connective tissues in vivo. Cells assembled by magnetic forces presented visual features representative of their in vivo states but largely absent in monolayers. This established the efficacy of contactless assembly as a means to fabricate in vitro tissue models. © 2016 John Wiley & Sons Ltd.

Improved Imaging of Magnetically Labeled Cells Using Rotational Magnetomotive Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Peter Cimalla

2017-04-01

Full Text Available In this paper, we present a reliable and robust method for magnetomotive optical coherence tomography (MM-OCT imaging of single cells labeled with iron oxide particles. This method employs modulated longitudinal and transverse magnetic fields to evoke alignment and rotation of anisotropic magnetic structures in the sample volume. Experimental evidence suggests that magnetic particles assemble themselves in elongated chains when exposed to a permanent magnetic field. Magnetomotion in the intracellular space was detected and visualized by means of 3D OCT as well as laser speckle reflectometry as a 2D reference imaging method. Our experiments on mesenchymal stem cells embedded in agar scaffolds show that the magnetomotive signal in rotational MM-OCT is significantly increased by a factor of ~3 compared to previous pulsed MM-OCT, although the solenoid’s power consumption was 16 times lower. Finally, we use our novel method to image ARPE-19 cells, a human retinal pigment epithelium cell line. Our results permit magnetomotive imaging with higher sensitivity and the use of low power magnetic fields or larger working distances for future three-dimensional cell tracking in target tissues and organs.

On-chip Magnetic Separation and Cell Encapsulation in Droplets

Science.gov (United States)

Chen, A.; Byvank, T.; Bharde, A.; Miller, B. L.; Chalmers, J. J.; Sooryakumar, R.; Chang, W.-J.; Bashir, R.

2012-02-01

The demand for high-throughput single cell assays is gaining importance because of the heterogeneity of many cell suspensions, even after significant initial sorting. These suspensions may display cell-to-cell variability at the gene expression level that could impact single cell functional genomics, cancer, stem-cell research and drug screening. The on-chip monitoring of individual cells in an isolated environment could prevent cross-contamination, provide high recovery yield and ability to study biological traits at a single cell level These advantages of on-chip biological experiments contrast to conventional methods, which require bulk samples that provide only averaged information on cell metabolism. We report on a device that integrates microfluidic technology with a magnetic tweezers array to combine the functionality of separation and encapsulation of objects such as immunomagnetically labeled cells or magnetic beads into pico-liter droplets on the same chip. The ability to control the separation throughput that is independent of the hydrodynamic droplet generation rate allows the encapsulation efficiency to be optimized. The device can potentially be integrated with on-chip labeling and/or bio-detection to become a powerful single-cell analysis device.

A magnetically responsive nanocomposite scaffold combined with Schwann cells promotes sciatic nerve regeneration upon exposure to magnetic field

Directory of Open Access Journals (Sweden)

Liu ZY

2017-10-01

Full Text Available Zhongyang Liu,1,* Shu Zhu,1,* Liang Liu,2,* Jun Ge,3,4,* Liangliang Huang,1 Zhen Sun,1 Wen Zeng,5 Jinghui Huang,1 Zhuojing Luo1 1Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi, 2Department of Orthopedics, No 161 Hospital of PLA, Wuhan, Hubei, 3Department of Orthopedics, No 323 Hospital of PLA, Xi’an, Shaanxi, 4Department of Anatomy, Fourth Military Medical University, Xi’an, Shaanxi, 5Department of Neurosurgery, Tangdu Hospital, Fourth Military Medical University, Xi’an, Shaanxi, People’s Republic of China *These authors contributed equally to this work Abstract: Peripheral nerve repair is still challenging for surgeons. Autologous nerve transplantation is the acknowledged therapy; however, its application is limited by the scarcity of available donor nerves, donor area morbidity, and neuroma formation. Biomaterials for engineering artificial nerves, particularly materials combined with supportive cells, display remarkable promising prospects. Schwann cells (SCs are the absorbing seeding cells in peripheral nerve engineering repair; however, the attenuated biologic activity restricts their application. In this study, a magnetic nanocomposite scaffold fabricated from magnetic nanoparticles and a biodegradable chitosan–glycerophosphate polymer was made. Its structure was evaluated and characterized. The combined effects of magnetic scaffold (MG with an applied magnetic field (MF on the viability of SCs and peripheral nerve injury repair were investigated. The magnetic nanocomposite scaffold showed tunable magnetization and degradation rate. The MGs synergized with the applied MF to enhance the viability of SCs after transplantation. Furthermore, nerve regeneration and functional recovery were promoted by the synergism of SCs-loaded MGs and MF. Based on the current findings, the combined application of MGs and SCs with applied MF is a promising therapy for the engineering of peripheral

New calcium-selective smart contrast agents for magnetic resonance imaging.

Science.gov (United States)

Verma, Kirti Dhingra; Forgács, Attila; Uh, Hyounsoo; Beyerlein, Michael; Maier, Martin E; Petoud, Stéphane; Botta, Mauro; Logothetis, Nikos K

2013-12-23

Calcium plays a vital role in the human body and especially in the central nervous system. Precise maintenance of Ca(2+) levels is very crucial for normal cell physiology and health. The deregulation of calcium homeostasis can lead to neuronal cell death and brain damage. To study this functional role played by Ca(2+) in the brain noninvasively by using magnetic resonance imaging, we have synthesized a new set of Ca(2+) -sensitive smart contrast agents (CAs). The agents were found to be highly selective to Ca(2+) in the presence of other competitive anions and cations in buffer and in physiological fluids. The structure of CAs comprises Gd(3+)-DO3A (DO3A=1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane) coupled to a Ca(2+) chelator o-amino phenol-N,N,O-triacetate (APTRA). The agents are designed to sense Ca(2+) present in extracellular fluid of the brain where its concentration is relatively high, that is, 1.2-0.8 mM. The determined dissociation constant of the CAs to Ca(2+) falls in the range required to sense and report changes in extracellular Ca(2+) levels followed by an increase in neural activity. In buffer, with the addition of Ca(2+) the increase in relaxivity ranged from 100-157%, the highest ever known for any T1-based Ca(2+)-sensitive smart CA. The CAs were analyzed extensively by the measurement of luminescence lifetime measurement on Tb(3+) analogues, nuclear magnetic relaxation dispersion (NMRD), and (17)O NMR transverse relaxation and shift experiments. The results obtained confirmed that the large relaxivity enhancement observed upon Ca(2+) addition is due to the increase of the hydration state of the complexes together with the slowing down of the molecular rotation and the retention of a significant contribution of the water molecules of the second sphere of hydration. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A smart magnetic resonance contrast agent for selective copper sensing.

Science.gov (United States)

Que, Emily L; Chang, Christopher J

2006-12-20

We describe the synthesis and properties of Copper-Gad-1 (CG1), a new type of smart magnetic resonance (MR) sensor for selective detection of copper. CG1 is composed of a gadolinium contrast agent core tethered to copper-selective recognition motif. Cu2+-induced modulation of inner-sphere water access to the Gd3+ center provides a sensing mechanism for reporting Cu2+ levels by reading out changes in longitudinal proton relaxivity values. CG1 features good selectivity for Cu2+ over abundant biological cations and a 41% increase in relaxivity upon Cu2+ binding and is capable of detecting micromolar changes in Cu2+ concentrations in aqueous media.

Selected topics in magnetism

CERN Document Server

Gupta, L C

1993-01-01

Part of the ""Frontiers in Solid State Sciences"" series, this volume presents essays on such topics as spin fluctuations in Heisenberg magnets, quenching of spin fluctuations by high magnetic fields, and kondo effect and heavy fermions in rare earths amongst others.

Selected applications of planar permanent magnet multipoles in FEL insertion device design

International Nuclear Information System (INIS)

Tatchyn, R.

1993-08-01

In recent work, a new class of magnetic multipoles based on planar configurations of permanent magnet (PM) material has been developed. These structures, in particular the quadrupole and sextupole, feature fully open horizontal apertures, and are comparable in effectiveness to conventional iron multipole structures. In this paper results of recent measurements of planar PM quadrupoles and sextupoles are reported and selected applications to FEL insertion device design are considered

Biodiesel production from waste cooking oil in a magnetically fluidized bed reactor using whole-cell biocatalysts

International Nuclear Information System (INIS)

Chen, Guanyi; Liu, Jing; Yao, Jingang; Qi, Yun; Yan, Beibei

2017-01-01

Highlights: • A MFBR system was used for biodiesel production from waste cooking oil. • Reaction parameters were optimized by response surface methodology. • Transesterification using MWCBs in MFBR obtained a max yield of 91.8% after 48 h. • The MWCBs can be reused in MFBR for 10 cycles with maintaining 87.5% yield. • The MFBR using MWCBs was an efficient system for large-scale biodiesel industry. - Abstract: Biodiesel production from catalytic transesterification of waste cooking oil (WCO) was investigated in a magnetically fluidized bed reactor (MFBR) over Pseudomonas mendocina cells immobilized in magnetic microspheres. The effects of methanol to oil molar ratio (MOMR), magnetic field intensity, biocatalysts concentration and reactant flow rate on biodiesel production were investigated. Optimization of the selected parameters was carried out for maximum biodiesel production using response surface methodology with support of Design-Expert software. The parameters optimized with response surface methodology were MOMR of 3.74:1, magnetic field intensity of 136.63 Oe, biocatalysts concentration of 10.21 wt.% and reactant flow rate of 16.97 mL/min. An experimental biodiesel yield of 91.8% was obtained at 35 °C after 48 h with these optimized parameters. Moreover, the magnetic whole-cell biocatalysts (MWCBs) exhibited good reusability in MFBR that 87.5% biodiesel yield could still be achieved after 10 cycles. The results suggested that MWCBs catalyzed transesterification in the MFBR system would have broad application prospects in biodiesel production.

Selection rules for single-chain-magnet behaviour in non-collinear Ising systems

International Nuclear Information System (INIS)

Vindigni, Alessandro; Pini, Maria Gloria

2009-01-01

The magnetic behaviour of molecular single-chain magnets is investigated in the framework of a one-dimensional Ising model with single spin-flip Glauber dynamics. Opportune modifications to the original theory are required in order to account for non-collinearity of local anisotropy axes between themselves and with respect to the crystallographic (laboratory) frame. The extension of Glauber's theory to the case of a collinear Ising ferrimagnetic chain is also discussed. Within this formalism, both the dynamics of magnetization reversal in zero field and the response of the system to a weak magnetic field, oscillating in time, are studied. Depending on the experimental geometry, selection rules are found for the occurrence of slow relaxation of the magnetization at low temperatures, as well as for resonant behaviour of the a.c. susceptibility as a function of temperature at low frequencies. The present theory applies successfully to some real systems, namely Mn-, Dy- and Co-based molecular magnetic chains, showing that single-chain-magnet behaviour is not only a feature of collinear ferro- and ferrimagnetic, but also of canted antiferromagnetic chains.

Selection rules for single-chain-magnet behaviour in non-collinear Ising systems

Energy Technology Data Exchange (ETDEWEB)

Vindigni, Alessandro [Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zuerich (Switzerland); Pini, Maria Gloria [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy)], E-mail: vindigni@phys.ethz.ch

2009-06-10

The magnetic behaviour of molecular single-chain magnets is investigated in the framework of a one-dimensional Ising model with single spin-flip Glauber dynamics. Opportune modifications to the original theory are required in order to account for non-collinearity of local anisotropy axes between themselves and with respect to the crystallographic (laboratory) frame. The extension of Glauber's theory to the case of a collinear Ising ferrimagnetic chain is also discussed. Within this formalism, both the dynamics of magnetization reversal in zero field and the response of the system to a weak magnetic field, oscillating in time, are studied. Depending on the experimental geometry, selection rules are found for the occurrence of slow relaxation of the magnetization at low temperatures, as well as for resonant behaviour of the a.c. susceptibility as a function of temperature at low frequencies. The present theory applies successfully to some real systems, namely Mn-, Dy- and Co-based molecular magnetic chains, showing that single-chain-magnet behaviour is not only a feature of collinear ferro- and ferrimagnetic, but also of canted antiferromagnetic chains.

Surface-modified magnetic nanoparticles for cell labeling

Czech Academy of Sciences Publication Activity Database

Zasońska, Beata Anna; Patsula, Vitalii; Stoika, R.; Horák, Daniel

2014-01-01

Roč. 13, č. 4 (2014), s. 63-73 ISSN 2305-7815 R&D Projects: GA MŠk(CZ) LH14318 Institutional support: RVO:61389013 Keywords : magnetic nanoparticles * surface-modified * cell labeling Subject RIV: CD - Macromolecular Chemistry

The effect of nonuniform magnetic targeting of intracoronary-delivering mesenchymal stem cells on coronary embolisation.

Science.gov (United States)

Huang, Zheyong; Shen, Yunli; Pei, Ning; Sun, Aijun; Xu, Jianfeng; Song, Yanan; Huang, Gangyong; Sun, Xiaoning; Zhang, Shuning; Qin, Qing; Zhu, Hongming; Yang, Shan; Yang, Xiangdong; Zou, Yunzeng; Qian, Juying; Ge, Junbo

2013-12-01

Magnetic targeting has been recently introduced to enhance cell retention in animals with acute myocardial infarction. However, it is unclear whether the magnetic accumulation of intravascular cells increases the risk of coronary embolism. Upon finite element analysis, we found that the permanent magnetic field was nonuniform, manifestated as attenuation along the vertical axis and polarisation along the horizontal axis. In the in vitro experiments, iron-labelled mesenchymal stem cells (MSCs) were accumulated in layers predominantly at the edge of the magnet. In an ischaemic rat model subjected to intracavitary MSCs injection, magnetic targeting induced unfavourable vascular embolisation and an inhomogeneous distribution of the donor cells, which prevented the enhanced cell retention from translating into additional functional benefit. These potential complications of magnetic targeting should be thoroughly investigated and overcome before clinical application. Copyright © 2013 Elsevier Ltd. All rights reserved.

Magnetofluidic concentration and separation of non-magnetic particles using two magnet arrays

Science.gov (United States)

Hejazian, Majid

2016-01-01

The present paper reports the use of diluted ferrofluid and two arrays of permanent magnets for the size-selective concentration of non-magnetic particles. The micro magnetofluidic device consists of a straight channels sandwiched between two arrays of permanent magnets. The permanent magnets create multiple capture zones with minimum magnetic field strength along the channel. The complex interaction between magnetic forces and hydrodynamic force allows the device to operate in different regimes suitable for concentration of non-magnetic particles with small difference in size. Our experimental results show that non-magnetic particles with diameters of 3.1 μm and 4.8 μm can be discriminated and separated with this method. The results from this study could be used as a guide for the design of size-sensitive separation devices for particle and cell based on negative magnetophoresis. PMID:27478527

Magnetic resonance imaging and cell-based neurorestorative therapy after brain injury

Directory of Open Access Journals (Sweden)

Quan Jiang

2016-01-01

Full Text Available Restorative cell-based therapies for experimental brain injury, such as stroke and traumatic brain injury, substantially improve functional outcome. We discuss and review state of the art magnetic resonance imaging methodologies and their applications related to cell-based treatment after brain injury. We focus on the potential of magnetic resonance imaging technique and its associated challenges to obtain useful new information related to cell migration, distribution, and quantitation, as well as vascular and neuronal remodeling in response to cell-based therapy after brain injury. The noninvasive nature of imaging might more readily help with translation of cell-based therapy from the laboratory to the clinic.

Isolating peripheral lymphocytes by density gradient centrifugation and magnetic cell sorting.

Science.gov (United States)

Brosseron, Frederic; Marcus, Katrin; May, Caroline

2015-01-01

Combining density gradient centrifugation with magnetic cell sorting provides a powerful tool to isolate blood cells with high reproducibility, yield, and purity. It also allows for subsequent separation of multiple cell types, resulting in the possibility to analyze different purified fractions from one donor's sample. The centrifugation step divides whole blood into peripheral blood mononuclear cells (PBMC), erythrocytes, and platelet-rich plasma. In the following, lymphocyte subtypes can be consecutively isolated from the PBMC fraction. This chapter describes enrichment of erythrocytes, CD14-positive monocytes and CD3-positive T lymphocytes. Alternatively, other cell types can be targeted by using magnetic beads specific for the desired subpopulation.

Graphene-Templated Synthesis of Magnetic Metal Organic Framework Nanocomposites for Selective Enrichment of Biomolecules.

Science.gov (United States)

Cheng, Gong; Wang, Zhi-Gang; Denagamage, Sachira; Zheng, Si-Yang

2016-04-27

Successful control of homogeneous and complete coating of graphene or graphene-based composites with well-defined metal organic framework (MOF) layers is a great challenge. Herein, novel magnetic graphene MOF composites were constructed via a simple strategy for self-assembly of well-distributed, dense, and highly porous MOFs on both sides of graphene nanosheets. Graphene functionalized with magnetic nanoparticles and carboxylic groups on both sides was explored as the backbone and template to direct the controllable self-assembly of MOFs. The prepared composite materials have a relatively high specific surface area (345.4 m(2) g(-1)), and their average pore size is measured to be 3.2 nm. Their relatively high saturation magnetization (23.8 emu g(-1)) indicates their strong magnetism at room temperature. Moreover, the multifunctional composite was demonstrated to be a highly effective affinity material in selective extraction and separation of low-concentration biomolecules from biological samples, in virtue of the size-selection property of the unique porous structure and the excellent affinity of the composite materials. Besides providing a solution for the construction of well-defined functional graphene-based MOFs, this work could also contribute to selective extraction of biomolecules, in virtue of the universal affinity between immobilized metal ions and biomolecules.

Selective Magnetic Evolution of MnxFe1-xO Nanoplates

KAUST Repository

Song, Hyon-Min

2015-04-27

Iron-manganese oxide (MnxFe1-xO) nanoplates were prepared by thermal decomposition method. Irregular development of crystalline phases was observed with the increase of annealing temperature. Magnetic properties are in accordance with their respective crystalline phases, and the selective magnetic evolution from their rich magnetism of MnxFe1-xO and MnFe2O4 is achieved by controlling the annealing conditions. Rock-salt structure of MnxFe1-xO (space group Fm-3m) is observed in as-synthesized nanoplates, while MnFe2O4 and MnxFe1-xO with significant magnetic interactions between them are observed at 380 °C. In nanoplates annealed at 450 °C, soft ferrites of Mn0.48Fe2.52O4 with MnxFe1-xO are observed. It is assumed that the differential and early development of crystalline phase of MnxFe1-xO, and the inhomogeneous cation mixing between Mn and Fe cause this rather extraordinary magnetic development. In particular, the prone nature of divalent metal oxides to cation vacancy and the prolonged annealing time of 15 hours which enables ordering are also thought to contribute to these irregularities.

Selective Magnetic Evolution of MnxFe1-xO Nanoplates

KAUST Repository

Song, Hyon-Min; Zink, Jeffrey I.; Khashab, Niveen M.

2015-01-01

Iron-manganese oxide (MnxFe1-xO) nanoplates were prepared by thermal decomposition method. Irregular development of crystalline phases was observed with the increase of annealing temperature. Magnetic properties are in accordance with their respective crystalline phases, and the selective magnetic evolution from their rich magnetism of MnxFe1-xO and MnFe2O4 is achieved by controlling the annealing conditions. Rock-salt structure of MnxFe1-xO (space group Fm-3m) is observed in as-synthesized nanoplates, while MnFe2O4 and MnxFe1-xO with significant magnetic interactions between them are observed at 380 °C. In nanoplates annealed at 450 °C, soft ferrites of Mn0.48Fe2.52O4 with MnxFe1-xO are observed. It is assumed that the differential and early development of crystalline phase of MnxFe1-xO, and the inhomogeneous cation mixing between Mn and Fe cause this rather extraordinary magnetic development. In particular, the prone nature of divalent metal oxides to cation vacancy and the prolonged annealing time of 15 hours which enables ordering are also thought to contribute to these irregularities.

Immunocapture of CD133-positive cells from human cancer cell lines by using monodisperse magnetic poly(glycidyl methacrylate) microspheres containing amino groups

Energy Technology Data Exchange (ETDEWEB)

Kuan, Wei-Chih [Department of Chemical Engineering, Systems Biology and Tissue Engineering Research Center, National Chung Cheng University, Minhisung 621, Taiwan (China); Horák, Daniel, E-mail: horak@imc.cas.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Plichta, Zdeněk [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Lee, Wen-Chien [Department of Chemical Engineering, Systems Biology and Tissue Engineering Research Center, National Chung Cheng University, Minhisung 621, Taiwan (China)

2014-01-01

Magnetic poly(glycidyl methacrylate)-based macroporous microspheres with an average particle size of 4.2 μm were prepared using a modified multi-step swelling polymerization method and by introducing amino functionality on their surfaces. Antibody molecules were oxidized on their carbohydrate moieties and bound to the amino-containing magnetic microspheres via a site-directed procedure. CD133-positive cells could be effectively captured from human cancer cell lines (HepG2, HCT116, MCF7, and IMR-32) by using magnetic microspheres conjugated to an anti-human CD133 antibody. After further culture, the immunocaptured CD133-expressing cells from IMR-32 proliferated and gradually detached from the magnetic microspheres. Flow-cytometric analysis confirmed the enrichment of CD133-expressing cells by using the antibody-bound magnetic microspheres. Such microspheres suitable for immunocapture are very promising for cancer diagnosis because the CD133-expressing cells in cancer cell lines have been suggested to be cancer stem cells. - Highlights: • Multi-step swelling polymerization produced poly(glycidyl methacrylate) microspheres. • Anti-human CD133 antibodies were bound to the amino-containing magnetic microspheres. • CD133-positive cells were effectively captured from human cancer cell lines. • Immunocaptured CD133-expressing cells proliferated and were detached from microspheres. • Enrichment of CD133-expressing cells was confirmed by flow-cytometric analysis.

Selective separation of lambdacyhalothrin by porous/magnetic molecularly imprinted polymers prepared by Pickering emulsion polymerization.

Science.gov (United States)

Hang, Hui; Li, Chunxiang; Pan, Jianming; Li, Linzi; Dai, Jiangdong; Dai, Xiaohui; Yu, Ping; Feng, Yonghai

2013-10-01

Porous/magnetic molecularly imprinted polymers (PM-MIPs) were prepared by Pickering emulsion polymerization. The reaction was carried out in an oil/water emulsion using magnetic halloysite nanotubes as the stabilizer instead of a toxic surfactant. In the oil phase, the imprinting process was conducted by radical polymerization of functional and cross-linked monomers, and porogen chloroform generated steam under the high reaction temperature, which resulted in some pores decorated with easily accessible molecular binding sites within the as-made PM-MIPs. The characterization demonstrated that the PM-MIPs were porous and magnetic inorganic-polymer composite microparticles with magnetic sensitivity (M(s) = 0.7448 emu/g), thermal stability (below 473 K) and magnetic stability (over the pH range of 2.0-8.0). The PM-MIPs were used as a sorbent for the selective binding of lambdacyhalothrin (LC) and rapidly separated under an external magnetic field. The Freundlich isotherm model gave a good fit to the experimental data. The adsorption kinetics of the PM-MIPs was well described by pseudo-second-order kinetics, indicating that the chemical process could be the rate-limiting step in the adsorption of LC. The selective recognition experiments exhibited the outstanding selective adsorption effect of the PM-MIPs for target LC. Moreover, the PM-MIPs regeneration without significant loss in adsorption capacity was demonstrated by at least four repeated cycles. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combining magnetic sorting of mother cells and fluctuation tests to analyze genome instability during mitotic cell aging in Saccharomyces cerevisiae.

Science.gov (United States)

Patterson, Melissa N; Maxwell, Patrick H

2014-10-16

Saccharomyces cerevisiae has been an excellent model system for examining mechanisms and consequences of genome instability. Information gained from this yeast model is relevant to many organisms, including humans, since DNA repair and DNA damage response factors are well conserved across diverse species. However, S. cerevisiae has not yet been used to fully address whether the rate of accumulating mutations changes with increasing replicative (mitotic) age due to technical constraints. For instance, measurements of yeast replicative lifespan through micromanipulation involve very small populations of cells, which prohibit detection of rare mutations. Genetic methods to enrich for mother cells in populations by inducing death of daughter cells have been developed, but population sizes are still limited by the frequency with which random mutations that compromise the selection systems occur. The current protocol takes advantage of magnetic sorting of surface-labeled yeast mother cells to obtain large enough populations of aging mother cells to quantify rare mutations through phenotypic selections. Mutation rates, measured through fluctuation tests, and mutation frequencies are first established for young cells and used to predict the frequency of mutations in mother cells of various replicative ages. Mutation frequencies are then determined for sorted mother cells, and the age of the mother cells is determined using flow cytometry by staining with a fluorescent reagent that detects bud scars formed on their cell surfaces during cell division. Comparison of predicted mutation frequencies based on the number of cell divisions to the frequencies experimentally observed for mother cells of a given replicative age can then identify whether there are age-related changes in the rate of accumulating mutations. Variations of this basic protocol provide the means to investigate the influence of alterations in specific gene functions or specific environmental conditions on

Transcranial magnetic stimulation promotes the proliferation of dopaminergic neuronal cells in vitro

Science.gov (United States)

Zhong, Xiaojing; Luo, Jie; Rastogi, Priyam; Kanthasamy, Anumantha G.; Jiles, David C.; Fellow, IEEE

2018-05-01

Transcranial magnetic stimulation (TMS) is a safe and non-invasive treatment for neurological disorders. TMS has been approved as a treatment for major depressive disorders by the US Food and Drug Administration (FDA) in 2008. Due to the phenomenon of electromagnetic induction, a time-varying magnetic field induces an electric field in the conductive tissues in the brain, TMS has the ability to activate neurons in vivo. However, the effects of the magnetic fields on neurons in cell culture have not been investigated adequately. The magnetic fields affect the neurons when the potential across the neuronal membrane exceeds the threshold which in turn causes an action potential. Based on these theories, we investigated the effects of the magnetic fields generated by a monophasic stimulator with a 70 mm double coil on rat dopaminergic neuronal cell lines (N27). The directions of the magnetic fields in each coil of the double coil oppose each other. The effects of changing the direction of the magnetic field on N27 neurons was also investigated. The results of the experiments showed that both of the fields perpendicular to the coil surface promoted the proliferation of N27 dopaminergic neurons. In order to investigate the gene expression and protein expression affected by TMS, quantitative Polymerase Chain Reaction (qPCR) was used. Here we report changes in glial cell line-derived neurotrophic factor (GDNF) in dopaminergic neuronal cells (N27) after TMS treatment.

Transcranial magnetic stimulation promotes the proliferation of dopaminergic neuronal cells in vitro

Directory of Open Access Journals (Sweden)

Xiaojing Zhong

2018-05-01

Full Text Available Transcranial magnetic stimulation (TMS is a safe and non-invasive treatment for neurological disorders. TMS has been approved as a treatment for major depressive disorders by the US Food and Drug Administration (FDA in 2008. Due to the phenomenon of electromagnetic induction, a time-varying magnetic field induces an electric field in the conductive tissues in the brain, TMS has the ability to activate neurons in vivo. However, the effects of the magnetic fields on neurons in cell culture have not been investigated adequately. The magnetic fields affect the neurons when the potential across the neuronal membrane exceeds the threshold which in turn causes an action potential. Based on these theories, we investigated the effects of the magnetic fields generated by a monophasic stimulator with a 70 mm double coil on rat dopaminergic neuronal cell lines (N27. The directions of the magnetic fields in each coil of the double coil oppose each other. The effects of changing the direction of the magnetic field on N27 neurons was also investigated. The results of the experiments showed that both of the fields perpendicular to the coil surface promoted the proliferation of N27 dopaminergic neurons. In order to investigate the gene expression and protein expression affected by TMS, quantitative Polymerase Chain Reaction (qPCR was used. Here we report changes in glial cell line-derived neurotrophic factor (GDNF in dopaminergic neuronal cells (N27 after TMS treatment.

Multistage Magnetic Separator of Cells and Proteins

Science.gov (United States)

Barton, Ken; Ainsworth, Mark; Daily, Bruce; Dunn, Scott; Metz, Bill; Vellinger, John; Taylor, Brock; Meador, Bruce

2005-01-01

The multistage electromagnetic separator for purifying cells and magnetic particles (MAGSEP) is a laboratory apparatus for separating and/or purifying particles (especially biological cells) on the basis of their magnetic susceptibility and magnetophoretic mobility. Whereas a typical prior apparatus based on similar principles offers only a single stage of separation, the MAGSEP, as its full name indicates, offers multiple stages of separation; this makes it possible to refine a sample population of particles to a higher level of purity or to categorize multiple portions of the sample on the basis of magnetic susceptibility and/or magnetophoretic mobility. The MAGSEP includes a processing unit and an electronic unit coupled to a personal computer. The processing unit includes upper and lower plates, a plate-rotation system, an electromagnet, an electromagnet-translation system, and a capture-magnet assembly. The plates are bolted together through a roller bearing that allows the plates to rotate with respect to each other. An interface between the plates acts as a seal for separating fluids. A lower cuvette can be aligned with as many as 15 upper cuvette stations for fraction collection during processing. A two-phase stepping motor drives the rotation system, causing the upper plate to rotate for the collection of each fraction of the sample material. The electromagnet generates a magnetic field across the lower cuvette, while the translation system translates the electromagnet upward along the lower cuvette. The current supplied to the electromagnet, and thus the magnetic flux density at the pole face of the electromagnet, can be set at a programmed value between 0 and 1,400 gauss (0.14 T). The rate of translation can be programmed between 5 and 2,000 m/s so as to align all sample particles in the same position in the cuvette. The capture magnet can be a permanent magnet. It is mounted on an arm connected to a stepping motor. The stepping motor rotates the arm to

A magnetic trap for living cells suspended in a paramagnetic buffer

Science.gov (United States)

Winkleman, Adam; Gudiksen, Katherine L.; Ryan, Declan; Whitesides, George M.; Greenfield, Derek; Prentiss, Mara

2004-09-01

This manuscript describes the fabrication and use of a three-dimensional magnetic trap for diamagnetic objects in an aqueous solution of paramagnetic ions; this trap uses permanent magnets. It demonstrates trapping of polystyrene spheres, and of various types of living cells: mouse fibroblast (NIH-3T3), yeast (Saccharomyces cerevisiae), and algae (Chlamydomonas reinhardtii). For a 40mM solution of gadolinium (III) diethylenetriaminepentaacetic acid (Gd .DTPA) in aqueous buffer, the smallest cell (particle) that could be trapped had a radius of ˜2.5μm. The trapped particle and location of the magnetic trap can be translated in three dimensions by independent manipulation of the permanent magnets. This letter a1so characterizes the biocompatibility of the trapping solution.

Hydrogen peroxide removal with magnetically responsive Saccharomyces cerevisiae cells

Czech Academy of Sciences Publication Activity Database

Šafařík, Ivo; Maděrová, Zdeňka; Šafaříková, Miroslava

2008-01-01

Roč. 56, - (2008), s. 7925-7928 ISSN 0021-8561 R&D Projects: GA MPO 2A-1TP1/094; GA MŠk OC 157 Institutional research plan: CEZ:AV0Z60870520 Keywords : magnetic alginate beads * catalase * magnetic separation * Saccharomyces cerevisiae cells * hydrogen peroxide Subject RIV: GM - Food Processing Impact factor: 2.562, year: 2008

Interactions of Cells with Magnetic Nanowires and Micro Needles

KAUST Repository

Perez, Jose E.

2017-12-01

The use of nanowires, nano and micro needles in biomedical applications has markedly increased in the past years, mainly due to attractive properties such as biocompatibility and simple fabrication. Specifically, these structures have shown promise in applications including cell separation, tumor cell capture, intracellular delivery, cell therapy, cancer treatment and as cell growth scaffolds. The work proposed here aims to study two platforms for different applications: a vertical magnetic nanowire array for mesenchymal stem cell differentiation and a micro needle platform for intracellular delivery. First, a thorough evaluation of the cytotoxicity of nanowires was done in order to understand how a biological system interacts with high aspect ratio structures. Nanowires were fabricated through pulsed electrodeposition and characterized by electron microscopy, vibrating sample magnetometry and energy dispersive X-ray spectroscopy. Studies of biocompatibility, cell death, cell membrane integrity, nanowire internalization and intracellular dissolution were all performed in order to characterize the cell response. Results showed a variable biocompatibility depending on nanowire concentration and incubation time, with cell death resulting from an apoptotic pathway arising after internalization. A vertical array of nanowires was then used as a scaffold for the differentiation of human mesenchymal stem cells. Using fluorescence and electron microscopy, the interactions between the dense array of nanowires and the cells were analyzed, as well as the biocompatibility of the array and its effects on cell differentiation. A magnetic field was additionally applied on the substrate to observe a possible differentiation. Stem cells grown on this scaffold showed a cytoskeleton and focal adhesion reorganization, and later expressed the osteogenic marker osteopontin. The application of a magnetic field counteracted this outcome. Lastly, a micro needle platform was fabricated

Magnetically modified biocells in constant magnetic field

Energy Technology Data Exchange (ETDEWEB)

Abramov, E.G.; Panina, L.K. [Saint Petersburg State University, St. Petersburg (Russian Federation); Kolikov, V.A., E-mail: kolikov1@yandex.ru [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation); Bogomolova, E.V. [Botanical Institute of the RAS after V.L.Komarov, St. Petersburg (Russian Federation); Snetov, V.N. [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation); Cherepkova, I.A. [Saint Petersburg State Institute of Technology, St. Petersburg (Russian Federation); Kiselev, A.A. [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation)

2017-02-01

Paper addresses the inverse problem in determining the area, where the external constant magnetic field captures the biological cells modified by the magnetic nanoparticles. Zero velocity isolines, in area where the modified cells are captured by the magnetic field were determined by numerical method for two locations of the magnet. The problem was solved taking into account the gravitational field, magnetic induction, density of medium, concentration and size of cells, and size and magnetization of nanoparticles attached to the cell. Increase in the number of the nanoparticles attached to the cell and decrease in the cell’ size, enlarges the area, where the modified cells are captured and concentrated by the magnet. Solution is confirmed by the visible pattern formation of the modified cells Saccharomyces cerevisiae. - Highlights: • The inverse problem was solved for finding zero velocity isolines of magnetically modified biological cells. • Solution of the inverse problem depends on the size of cells and the number of nanoparticles attached to the single cell. • The experimental data are in agreement with theoretical solution.

Multi-bits memory cell using degenerated magnetic states in a synthetic antiferromagnetic reference layer

International Nuclear Information System (INIS)

Fukushima, Akio; Yakushiji, Kay; Konoto, Makoto; Kubota, Hitoshi; Imamura, Hiroshi; Yuasa, Shinji

2016-01-01

We newly developed a magnetic memory cell having multi-bit function. The memory cell composed of a perpendicularly magnetized magnetic tunnel junction (MB-pMTJ) and a synthetic antiferromagnetic reference layer. The multi-bit function is realized by combining the freedom of states of the magnetic free layer and that in the antiferromagnetically coupled reference layer. The structure of the reference layer is (FeB/Ta/[Co/Pt]_3)/Ru/([Co/Pt]_6); the top and the bottom layers are coupled through Ru layer where the reference layer has two degrees of freedom of a head-to-head and a bottom-to-bottom magnetic configuration. A four-state memory cell is realized by combination of both degrees of freedom. The states in the reference layer however is hardly detected by the total resistance of MB-pMTJ, because the magnetoresistance effect in the reference layer is negligibly small. That implies that the resistance values for the different states in the reference layer are degenerated. On the other hand, the two different states in the reference layer bring different stray fields to the free layer, which generate two different minor loop with different switching fields. Therefore, the magnetic states in the reference layer can be differentiated by the two-step reading, before and after applying the appropriately pulsed magnetic field which can identify the initial state in the reference layer. This method is similar to distinguishing different magnetic states in an in-plane magnetized spin-valve element. We demonstrated that four different states in the MB-pMTJ can be distinguished by the two-step read-out. The important feature of the two-step reading is a practically large operation margins (large resistance change in reading) which is equal to that of a single MTJ. Even though the two-step reading is a destructive method by which 50% of the magnetic state is changed, this MB-pMTJ is promising for high density non-volatile memory cell with a minor cost of operation speed

Evaluation of In-Situ Magnetic Signals from Iron Oxide Nanoparticle-Labeled PC12 Cells by Atomic Force Microscopy.

Science.gov (United States)

Wang, Lijun; Min, Yue; Wang, Zhigang; Riggio, Cristina; Calatayud, M Pilar; Pinkernelle, Josephine; Raffa, Vittoria; Goya, Gerardo F; Keilhoff, Gerburg; Cuschieri, Alfred

2015-03-01

The magnetic signals from magnetite nanoparticle-labeled PC12 cells were assessed by magnetic force microscopy by deploying a localized external magnetic field to magnetize the nanoparticles and the magnetic tip simultaneously so that the interaction between the tip and PC12 cell-associated Fe3O4 nanoparticles could be detected at lift heights (the distance between the tip and the sample) larger than 100 nm. The use of large lift heights during the raster scanning of the probe eliminates the non-magnetic interference from the complex and rugged cell surface and yet maintains the sufficient sensitivity for magnetic detection. The magnetic signals of the cell-bound nanoparticles were semi-quantified by analyzing cell surface roughness upon three-dimensional reconstruction generated by the phase shift of the cantilever oscillation. The obtained data can be used for the evaluation of the overall cellular magnetization as well as the maximum magnetic forces from magnetic nanoparticle-labeled cells which is crucial for the biomedical application of these nanomaterials.

Cryogenics - Its influence on the selection of the ASTROMAG superconducting magnet coils

Science.gov (United States)

Green, M. A.

1990-01-01

ASTROMAG, a particle astrophysics experimental facility proposed for running alongside a Space Station, has a large superconducting magnet to analyze particles coming from deep space. Several types of magnets were investigated for use in the ASTROMAG central facility. The factors which influence the selection of the magnet coil design include: (1) the upper limit of particle momentum resolved (proportional to the integrated field) as a function of solid angle; (2)cryogenic design and its effect on cryogen lifetime for a given central facility mass; and (3) the overall cost of the magnet coils and cryostat. Four magnet types are analyzed in this paper. These include a simple two-coil solenoid (the baseline design),two disk coils at the ends of the helium tank, a two-coil toroid and a thin solenoid plus bucking coil. A balance must be struck between cryostat lifetime, total mass and the integrated field through the detectors. This balance tends to favor coils which are in the same vacuum vessel as the cryogen.

Self-assembled magnetic filter for highly efficient immunomagnetic separation.

Science.gov (United States)

Issadore, David; Shao, Huilin; Chung, Jaehoon; Newton, Andita; Pittet, Mikael; Weissleder, Ralph; Lee, Hakho

2011-01-07

We have developed a compact and inexpensive microfluidic chip, the self-assembled magnetic filter, to efficiently remove magnetically tagged cells from suspension. The self-assembled magnetic filter consists of a microfluidic channel built directly above a self-assembled NdFeB magnet. Micrometre-sized grains of NdFeB assemble to form alternating magnetic dipoles, creating a magnetic field with a very strong magnitude B (from the material) and field gradient ▽B (from the configuration) in the microfluidic channel. The magnetic force imparted on magnetic beads is measured to be comparable to state-of-the-art microfabricated magnets, allowing for efficient separations to be performed in a compact, simple device. The efficiency of the magnetic filter is characterized by sorting non-magnetic (polystyrene) beads from magnetic beads (iron oxide). The filter enriches the population of non-magnetic beads to magnetic beads by a factor of >10(5) with a recovery rate of 90% at 1 mL h(-1). The utility of the magnetic filter is demonstrated with a microfluidic device that sorts tumor cells from leukocytes using negative immunomagnetic selection, and concentrates the tumor cells on an integrated membrane filter for optical detection.

Magnetic Nano- and Micro- Particles in Living Cells: Kinetics and Fluctuations

Science.gov (United States)

Pease, C.; Chiang, N.; Pierce, C.; Muthusamy, N.; Sooryakumar, R.

2015-03-01

Functional nano and micro materials have recently been used not only as diagnostic tools for extracellular studies but also as intracellular drug delivery vehicles and as internal probes of the cell. To realize proper cellular applications, it is important not only to achieve efficient delivery of these materials to targeted cells, but also to control their movement and activity within the confines of the cell. In this presentation, superparamagnetic nano and micro particles are utilized as probes, with their responses to weak external magnetic fields enabling them to be maneuvered within a cell. In order to generate the required local magnetic fields needed for manipulation, the fields emanating from microscopic domain walls stabilized on patterned surface profiles are used in conjunction with weak external magnetic fields to create mobile traps that can localize and transport the internalized particle. Preliminary findings on creating the mobile traps suitable for applications to probe the interior of cells, and the responses, both Brownian fluctuations and directed motion, of particles ranging in size from 200 nm to 1 micron within HS-5 cells will be presented. Future applications to probe cellular behavior within the framework of emerging biomaterials will be discussed.

Magnetic Hyperthermia and Oxidative Damage to DNA of Human Hepatocarcinoma Cells.

Science.gov (United States)

Cellai, Filippo; Munnia, Armelle; Viti, Jessica; Doumett, Saer; Ravagli, Costanza; Ceni, Elisabetta; Mello, Tommaso; Polvani, Simone; Giese, Roger W; Baldi, Giovanni; Galli, Andrea; Peluso, Marco E M

2017-04-29

Nanotechnology is addressing major urgent needs for cancer treatment. We conducted a study to compare the frequency of 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3 H )-one deoxyguanosine (M₁dG) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) adducts, biomarkers of oxidative stress and/or lipid peroxidation, on human hepatocarcinoma HepG2 cells exposed to increasing levels of Fe₃O₄-nanoparticles (NPs) versus untreated cells at different lengths of incubations, and in the presence of increasing exposures to an alternating magnetic field (AMF) of 186 kHz using 32 P-postlabeling. The levels of oxidative damage tended to increase significantly after ≥24 h of incubations compared to controls. The oxidative DNA damage tended to reach a steady-state after treatment with 60 μg/mL of Fe₃O₄-NPs. Significant dose-response relationships were observed. A greater adduct production was observed after magnetic hyperthermia, with the highest amounts of oxidative lesions after 40 min exposure to AMF. The effects of magnetic hyperthermia were significantly increased with exposure and incubation times. Most important, the levels of oxidative lesions in AMF exposed NP treated cells were up to 20-fold greater relative to those observed in nonexposed NP treated cells. Generation of oxidative lesions may be a mechanism by which magnetic hyperthermia induces cancer cell death.

Protein purification using magnetic adsorbent particles

DEFF Research Database (Denmark)

Franzreb, M; Siemann-Herzberg, M.; Hobley, Timothy John

2006-01-01

The application of functionalised magnetic adsorbent particles in combination with magnetic separation techniques has received considerable attention in recent years. The magnetically responsive nature of such adsorbent particles permits their selective manipulation and separation in the presence...... separations are fast, gentle, scaleable, easily automated, can achieve separations that would be impossible or impractical to achieve by other techniques, and have demonstrated credibility in a wide range of disciplines, including minerals processing, wastewater treatment, molecular biology, cell sorting...

Hypericin-bearing magnetic iron oxide nanoparticles for selective drug delivery in photodynamic therapy.

Science.gov (United States)

Unterweger, Harald; Subatzus, Daniel; Tietze, Rainer; Janko, Christina; Poettler, Marina; Stiegelschmitt, Alfons; Schuster, Matthias; Maake, Caroline; Boccaccini, Aldo R; Alexiou, Christoph

2015-01-01

Combining the concept of magnetic drug targeting and photodynamic therapy is a promising approach for the treatment of cancer. A high selectivity as well as significant fewer side effects can be achieved by this method, since the therapeutic treatment only takes place in the area where accumulation of the particles by an external electromagnet and radiation by a laser system overlap. In this article, a novel hypericin-bearing drug delivery system has been developed by synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) with a hypericin-linked functionalized dextran coating. For that, sterically stabilized dextran-coated SPIONs were produced by coprecipitation and crosslinking with epichlorohydrin to enhance stability. Carboxymethylation of the dextran shell provided a functionalized platform for linking hypericin via glutaraldehyde. Particle sizes obtained by dynamic light scattering were in a range of 55-85 nm, whereas investigation of single magnetite or maghemite particle diameter was performed by transmission electron microscopy and X-ray diffraction and resulted in approximately 4.5-5.0 nm. Surface chemistry of those particles was evaluated by Fourier transform infrared spectroscopy and ζ potential measurements, indicating successful functionalization and dispersal stabilization due to a mixture of steric and electrostatic repulsion. Flow cytometry revealed no toxicity of pure nanoparticles as well as hypericin without exposure to light on Jurkat T-cells, whereas the combination of hypericin, alone or loaded on particles, with light-induced cell death in a concentration and exposure time-dependent manner due to the generation of reactive oxygen species. In conclusion, the combination of SPIONs' targeting abilities with hypericin's phototoxic properties represents a promising approach for merging magnetic drug targeting with photodynamic therapy for the treatment of cancer.

Magnetic micro-manipulations to probe the local physical properties of porous scaffolds and to confine stem cells.

Science.gov (United States)

Robert, Damien; Fayol, Delphine; Le Visage, Catherine; Frasca, Guillaume; Brulé, Séverine; Ménager, Christine; Gazeau, Florence; Letourneur, Didier; Wilhelm, Claire

2010-03-01

The in vitro generation of engineered tissue constructs involves the seeding of cells into porous scaffolds. Ongoing challenges are to design scaffolds to meet biochemical and mechanical requirements and to optimize cell seeding in the constructs. In this context, we have developed a simple method based on a magnetic tweezer set-up to manipulate, probe, and position magnetic objects inside a porous scaffold. The magnetic force acting on magnetic objects of various sizes serves as a control parameter to retrieve the local viscosity of the scaffolds internal channels as well as the stiffness of the scaffolds pores. Labeling of human stem cells with iron oxide magnetic nanoparticles makes it possible to perform the same type of measurement with cells as probes and evaluate their own microenvironment. For 18 microm diameter magnetic beads or magnetically labeled stem cells of similar diameter, the viscosity was equivalently equal to 20 mPa s in average. This apparent viscosity was then found to increase with the magnetic probes sizes. The stiffness probed with 100 microm magnetic beads was found in the 50 Pa range, and was lowered by a factor 5 when probed with cells aggregates. The magnetic forces were also successfully applied to the stem cells to enhance the cell seeding process and impose a well defined spatial organization into the scaffold. (c) 2009 Elsevier Ltd. All rights reserved.

Dynamics of magnetic particles in cylindrical Halbach array: implications for magnetic cell separation and drug targeting.

Science.gov (United States)

Babinec, Peter; Krafcík, Andrej; Babincová, Melánia; Rosenecker, Joseph

2010-08-01

Magnetic nanoparticles for therapy and diagnosis are at the leading edge of the rapidly developing field of bionanotechnology. In this study, we have theoretically studied motion of magnetic nano- as well as micro-particles in the field of cylindrical Halbach array of permanent magnets. Magnetic flux density was modeled as magnetostatic problem by finite element method and particle motion was described using system of ordinary differential equations--Newton law. Computations were done for nanoparticles Nanomag-D with radius 65 nm, which are often used in magnetic drug targeting, as well as microparticles DynaBeads-M280 with radius 1.4 microm, which can be used for magnetic separation. Analyzing snapshots of trajectories of hundred magnetite particles of each size in the water as well as in the air, we have found that optimally designed magnetic circuits of permanent magnets in quadrupolar Halbach array have substantially shorter capture time than simple blocks of permanent magnets commonly used in experiments, therefore, such a Halbach array may be useful as a potential source of magnetic field for magnetic separation and targeting of magnetic nanoparticles as well as microparticles for delivery of drugs, genes, and cells in various biomedical applications.

Reduction of the Earth's magnetic field inhibits growth rates of model cancer cell lines.

Science.gov (United States)

Martino, Carlos F; Portelli, Lucas; McCabe, Kevin; Hernandez, Mark; Barnes, Frank

2010-12-01

Small alterations in static magnetic fields have been shown to affect certain chemical reaction rates ex vivo. In this manuscript, we present data demonstrating that similar small changes in static magnetic fields between individual cell culture incubators results in significantly altered cell cycle rates for multiple cancer-derived cell lines. This change as assessed by cell number is not a result of apoptosis, necrosis, or cell cycle alterations. While the underlying mechanism is unclear, the implications for all cell culture experiments are clear; static magnetic field conditions within incubators must be considered and/or controlled just as one does for temperature, humidity, and carbon dioxide concentration. Copyright © 2010 Wiley-Liss, Inc.

Effect of low frequency magnetic fields on the growth of MNP-treated HT29 colon cancer cells

Science.gov (United States)

Spyridopoulou, K.; Makridis, A.; Maniotis, N.; Karypidou, N.; Myrovali, E.; Samaras, T.; Angelakeris, M.; Chlichlia, K.; Kalogirou, O.

2018-04-01

Recent investigations have attempted to understand and exploit the impact of magnetic field-actuated internalized magnetic nanoparticles (MNPs) on the proliferation rate of cancer cells. Due to the complexity of the parameters governing magnetic field-exposure though, individual studies to date have raised contradictory results. In our approach we performed a comparative analysis of key parameters related to the cell exposure of cancer cells to magnetic field-actuated MNPs, and to the magnetic field, in order to better understand the factors affecting cellular responses to magnetic field-stimulated MNPs. We used magnetite MNPs with a hydrodynamic diameter of 100 nm and studied the proliferation rate of MNPs-treated versus untreated HT29 human colon cancer cells, exposed to either static or alternating low frequency magnetic fields with varying intensity (40-200 mT), frequency (0-8 Hz) and field gradient. All three parameters, field intensity, frequency, and field gradient affected the growth rate of cells, with or without internalized MNPs, as compared to control MNPs-untreated and magnetic field-untreated cells. We observed that the growth inhibitory effects induced by static and rotating magnetic fields were enhanced by pre-treating the cells with MNPs, while the growth promoting effects observed in alternating field-treated cells were weakened by MNPs. Compared to static, rotating magnetic fields of the same intensity induced a similar extend of cell growth inhibition, while alternating fields of varying intensity (70 or 100 mT) and frequency (0, 4 or 8 Hz) induced cell proliferation in a frequency-dependent manner. These results, highlighting the diverse effects of mode, intensity, and frequency of the magnetic field on cell growth, indicate that consistent and reproducible results can be achieved by controlling the complexity of the exposure of biological samples to MNPs and external magnetic fields, through monitoring crucial experimental parameters. We

Magnetically separable polymer (Mag-MIP) for selective analysis of biotin in food samples.

Science.gov (United States)

Uzuriaga-Sánchez, Rosario Josefina; Khan, Sabir; Wong, Ademar; Picasso, Gino; Pividori, Maria Isabel; Sotomayor, Maria Del Pilar Taboada

2016-01-01

This work presents an efficient method for the preparation of magnetic nanoparticles modified with molecularly imprinted polymers (Mag-MIP) through core-shell method for the determination of biotin in milk food samples. The functional monomer acrylic acid was selected from molecular modeling, EGDMA was used as cross-linking monomer and AIBN as radical initiator. The Mag-MIP and Mag-NIP were characterized by FTIR, magnetic hysteresis, XRD, SEM and N2-sorption measurements. The capacity of Mag-MIP for biotin adsorption, its kinetics and selectivity were studied in detail. The adsorption data was well described by Freundlich isotherm model with adsorption equilibrium constant (KF) of 1.46 mL g(-1). The selectivity experiments revealed that prepared Mag-MIP had higher selectivity toward biotin compared to other molecules with different chemical structure. The material was successfully applied for the determination of biotin in diverse milk samples using HPLC for quantification of the analyte, obtaining the mean value of 87.4% recovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Towards The Generation of Functionalized Magnetic Nanowires to Target Leukemic Cells

KAUST Repository

Alsharif, Nouf

2016-01-01

. In addition the NWs can be coated and functionalized to target cells of interest and, upon exposure to an alternating magnetic field, have been shown to induce cell death on several types of adherent cells, including several cancer cell types. For suspension

Particle compositions with a pre-selected cell internalization mode

Science.gov (United States)

Decuzzi, Paolo (Inventor); Ferrari, Mauro (Inventor)

2012-01-01

A method of formulating a particle composition having a pre-selected cell internalization mode involves selecting a target cell having surface receptors and obtaining particles that have i) surface moieties, that have an affinity for or are capable of binding to the surface receptors of the cell and ii) a preselected shape, where a surface distribution of the surface moieties on the particles and the shape of the particles are effective for the pre-selected cell internalization mode.

The Predictive Value of Selection Criteria in an Urban Magnet School

Science.gov (United States)

Lohmeier, Jill Hendrickson; Raad, Jennifer

2012-01-01

The predictive value of selection criteria on outcome data from two cohorts of students (Total N = 525) accepted to an urban magnet high school were evaluated. Regression analyses of typical screening variables (suspensions, absences, metropolitan achievement tests, middle school grade point averages [GPAs], Matrix Analogies test scores, and…

Magnetically levitated mesenchymal stem cell spheroids cultured with a collagen gel maintain phenotype and quiescence

Directory of Open Access Journals (Sweden)

Natasha S Lewis

2017-04-01

Full Text Available Multicellular spheroids are an established system for three-dimensional cell culture. Spheroids are typically generated using hanging drop or non-adherent culture; however, an emerging technique is to use magnetic levitation. Herein, mesenchymal stem cell spheroids were generated using magnetic nanoparticles and subsequently cultured within a type I collagen gel, with a view towards developing a bone marrow niche environment. Cells were loaded with magnetic nanoparticles, and suspended beneath an external magnet, inducing self-assembly of multicellular spheroids. Cells in spheroids were viable and compared to corresponding monolayer controls, maintained stem cell phenotype and were quiescent. Interestingly, core spheroid necrosis was not observed, even with increasing spheroid size, in contrast to other commonly used spheroid systems. This mesenchymal stem cell spheroid culture presents a potential platform for modelling in vitro bone marrow stem cell niches, elucidating interactions between cells, as well as a useful model for drug delivery studies.

Magnet power supply system for the ISABELLE half-cell prototype

International Nuclear Information System (INIS)

Nawrocky, R.J.

1977-01-01

Due to stringent requirements on the spatial harmonic content of ISABELLE's magnetic field, the magnet power supplies for the half-cell prototype must be dynamically accurate and stable to within 0.01% of their full-scale rating. Depending on the application, the full-scale current of various units comprising the system ranges from +-50 A to 4000 A. The system, as constructed is fully controllable and programmable either manually or with a control computer. The magnet power supply system described was constructed and interconnected with the half-cell computer control equipment. A number of power supply units were tested with inductive test loads in both the manual and the computer control modes. Test results on stability and speed of response indicate that all systems perform according to specifications

Boost Converter with Three-State Switching Cell and Integrated Magnetics

DEFF Research Database (Denmark)

Klimczak, Pawel; Munk-Nielsen, Stig

2009-01-01

Fuel cell systems often require high voltage gain and dc-dc step-up converter is a critical part. Scope of this paper is integration of inductor and transformer on a single core. Usage of integrated magnetics improves utilization of magnetic core and thus size and weight of the converter may...

Combination of hyperthermia and photodynamic therapy on mesenchymal stem cell line treated with chloroaluminum phthalocyanine magnetic-nanoemulsion

Energy Technology Data Exchange (ETDEWEB)

Paula, Leonardo B. de [Departamento de Química, Centro de Nanotecnologia e Engenharia Tecidual, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901 (Brazil); Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14049-900 (Brazil); Primo, Fernando L. [Departamento de Química, Centro de Nanotecnologia e Engenharia Tecidual, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901 (Brazil); Nanophoton Company, SUPERA Innovation and Technology Park, Av. Doutora Nadir de Aguiar, 1805, Universidade de São Paulo, Ribeirão Preto, P 14056-680 (Brazil); Pinto, Marcelo R. [Departamento de Química, Laboratório de Enzimologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901 (Brazil); Morais, Paulo C. [Instituto de Física, Universidade de Brasília, Brasília, DF 70910-900 (Brazil); School of Automation, Huazhong University of Science and Technology, Wuhan 430074 (China); and others

2015-04-15

The present study reports on the preparation and the cell viability assay of two nanoemulsions loaded with magnetic nanoparticle and chloroaluminum phthalocyanine. The preparations contain equal amount of chloroaluminum phthalocyanine (0.05 mg/mL) but different contents of magnetic nanoparticle (0.15×10{sup 13} or 1.50×10{sup 13} particle/mL). The human bone marrow mesenchymal stem cell line was used as the model to assess the cell viability and this type of cell can be used as a model to mimic cancer stem cells. The cell viability assays were performed in isolated as well as under combined magnetic hyperthermia and photodynamic therapy treatments. We found from the cell viability assay that under the hyperthermia treatment (1 MHz and 40 Oe magnetic field amplitude) the cell viability reduction was about 10%, regardless the magnetic nanoparticle content within the magnetic nanoparticle/chloroaluminum phthalocyanine formulation. However, cell viability reduction of about 50% and 60% were found while applying the photodynamic therapy treatment using the magnetic nanoparticle/chloroaluminum phthalocyanine formulation containing 0.15×10{sup 13} or 1.50×10{sup 13} magnetic particle/mL, respectively. Finally, an average reduction in cell viability of about 66% was found while combining the hyperthermia and photodynamic therapy treatments. - Highlights: • Current protocols in nanotechnology allow for biocompatible magnetic nanoparticles being associated with photosensitizer photoactive drugs, which could lead to perfectly controlled drug release. • The combination of the HPT and PDT therapies can be useful to develop further protocols for both advanced in vitro and in vivo assays. • Magnetic nanodevices associated with therapies have led to the decreased of proliferation of cell population that provides a favorable environment for tumor progression.

Combination of hyperthermia and photodynamic therapy on mesenchymal stem cell line treated with chloroaluminum phthalocyanine magnetic-nanoemulsion

International Nuclear Information System (INIS)

Paula, Leonardo B. de; Primo, Fernando L.; Pinto, Marcelo R.; Morais, Paulo C.

2015-01-01

The present study reports on the preparation and the cell viability assay of two nanoemulsions loaded with magnetic nanoparticle and chloroaluminum phthalocyanine. The preparations contain equal amount of chloroaluminum phthalocyanine (0.05 mg/mL) but different contents of magnetic nanoparticle (0.15×10 13 or 1.50×10 13 particle/mL). The human bone marrow mesenchymal stem cell line was used as the model to assess the cell viability and this type of cell can be used as a model to mimic cancer stem cells. The cell viability assays were performed in isolated as well as under combined magnetic hyperthermia and photodynamic therapy treatments. We found from the cell viability assay that under the hyperthermia treatment (1 MHz and 40 Oe magnetic field amplitude) the cell viability reduction was about 10%, regardless the magnetic nanoparticle content within the magnetic nanoparticle/chloroaluminum phthalocyanine formulation. However, cell viability reduction of about 50% and 60% were found while applying the photodynamic therapy treatment using the magnetic nanoparticle/chloroaluminum phthalocyanine formulation containing 0.15×10 13 or 1.50×10 13 magnetic particle/mL, respectively. Finally, an average reduction in cell viability of about 66% was found while combining the hyperthermia and photodynamic therapy treatments. - Highlights: • Current protocols in nanotechnology allow for biocompatible magnetic nanoparticles being associated with photosensitizer photoactive drugs, which could lead to perfectly controlled drug release. • The combination of the HPT and PDT therapies can be useful to develop further protocols for both advanced in vitro and in vivo assays. • Magnetic nanodevices associated with therapies have led to the decreased of proliferation of cell population that provides a favorable environment for tumor progression

Magnetic Hyperthermia and Oxidative Damage to DNA of Human Hepatocarcinoma Cells

Directory of Open Access Journals (Sweden)

Filippo Cellai

2017-04-01

Full Text Available Nanotechnology is addressing major urgent needs for cancer treatment. We conducted a study to compare the frequency of 3-(2-deoxy-β-d-erythro-pentafuranosylpyrimido[1,2-α]purin-10(3H-one deoxyguanosine (M1dG and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG adducts, biomarkers of oxidative stress and/or lipid peroxidation, on human hepatocarcinoma HepG2 cells exposed to increasing levels of Fe3O4-nanoparticles (NPs versus untreated cells at different lengths of incubations, and in the presence of increasing exposures to an alternating magnetic field (AMF of 186 kHz using 32P-postlabeling. The levels of oxidative damage tended to increase significantly after ≥24 h of incubations compared to controls. The oxidative DNA damage tended to reach a steady-state after treatment with 60 μg/mL of Fe3O4-NPs. Significant dose–response relationships were observed. A greater adduct production was observed after magnetic hyperthermia, with the highest amounts of oxidative lesions after 40 min exposure to AMF. The effects of magnetic hyperthermia were significantly increased with exposure and incubation times. Most important, the levels of oxidative lesions in AMF exposed NP treated cells were up to 20-fold greater relative to those observed in nonexposed NP treated cells. Generation of oxidative lesions may be a mechanism by which magnetic hyperthermia induces cancer cell death.

Selection of Amino Acid Chirality via Neutrino Interactions with 14N in Crossed Electric and Magnetic Fields

Science.gov (United States)

Boyd, Richard N.; Kajino, Toshitaka; Onaka, Takashi

2018-01-01

Abstract Previous work has suggested that the chirality of the amino acids could be established in the magnetic field of a nascent neutron star from a core-collapse supernova or massive collapsar. The magnetic field would orient the 14N nuclei, and the alignment of its nuclear spin with respect to those of the electron antineutrinos emitted from the collapsing star would determine the probability of destruction of the 14N nuclei by interactions with the antineutrinos. Subsequent work estimated the bulk polarization of the 14N nuclei in large rotating meteoroids in such an environment. The present work adds a crucial piece of this model by describing the details by which the selective 14N nuclear destruction would produce molecular chiral selectivity. The effects of the neutrino-induced interactions on the 14N nuclei bound in amino acids polarized in strong magnetic fields are studied. It is shown that electric fields in the reference frame of the nuclei modify the magnetic field at the nucleus, creating nuclear magnetizations that are asymmetric in chirality. The antineutrino cross sections depend on this magnetization, creating a selective destructive effect. The environmental conditions and sites in which such a selection mechanism could occur are discussed. Selective destruction of D-enantiomers results in enantiomeric excesses which may be sufficient to drive subsequent autocatalysis necessary to produce the few-percent enantiomeric excesses found in meteorites and subsequent homochirality. Molecular quantum chemical calculations were performed for alanine, and the chirality-dependent effects studied were included. A preference for left-handed molecules was found, and enantiomeric excesses as high as 0.02% were estimated for molecules in the electromagnetic conditions expected from a core-collapse supernova. Key Words: Amino acids—Supernovae—Antineutrinos—Enantiomeric excess—Chirality. Astrobiology 18, 190–206. PMID:29160728

Single-cell magnetic imaging using a quantum diamond microscope.

Science.gov (United States)

Glenn, D R; Lee, K; Park, H; Weissleder, R; Yacoby, A; Lukin, M D; Lee, H; Walsworth, R L; Connolly, C B

2015-08-01

We apply a quantum diamond microscope for detection and imaging of immunomagnetically labeled cells. This instrument uses nitrogen-vacancy (NV) centers in diamond for correlated magnetic and fluorescence imaging. Our device provides single-cell resolution and a field of view (∼1 mm(2)) two orders of magnitude larger than that of previous NV imaging technologies, enabling practical applications. To illustrate, we quantified cancer biomarkers expressed by rare tumor cells in a large population of healthy cells.

A 3D magnetic tissue stretcher for remote mechanical control of embryonic stem cell differentiation.

Science.gov (United States)

Du, Vicard; Luciani, Nathalie; Richard, Sophie; Mary, Gaëtan; Gay, Cyprien; Mazuel, François; Reffay, Myriam; Menasché, Philippe; Agbulut, Onnik; Wilhelm, Claire

2017-09-12

The ability to create a 3D tissue structure from individual cells and then to stimulate it at will is a major goal for both the biophysics and regenerative medicine communities. Here we show an integrated set of magnetic techniques that meet this challenge using embryonic stem cells (ESCs). We assessed the impact of magnetic nanoparticles internalization on ESCs viability, proliferation, pluripotency and differentiation profiles. We developed magnetic attractors capable of aggregating the cells remotely into a 3D embryoid body. This magnetic approach to embryoid body formation has no discernible impact on ESC differentiation pathways, as compared to the hanging drop method. It is also the base of the final magnetic device, composed of opposing magnetic attractors in order to form embryoid bodies in situ, then stretch them, and mechanically stimulate them at will. These stretched and cyclic purely mechanical stimulations were sufficient to drive ESCs differentiation towards the mesodermal cardiac pathway.The development of embryoid bodies that are responsive to external stimuli is of great interest in tissue engineering. Here, the authors culture embryonic stem cells with magnetic nanoparticles and show that the presence of magnetic fields could affect their aggregation and differentiation.

Optical Pumping Spin Exchange 3He Gas Cells for Magnetic Resonance Imaging

Science.gov (United States)

Kim, W.; Stepanyan, S. S.; Kim, A.; Jung, Y.; Woo, S.; Yurov, M.; Jang, J.

2009-08-01

We present a device for spin-exchange optical pumping system to produce large quantities of polarized noble gases for Magnetic Resonance Imaging (MRI). A method and design of apparatus for pumping the polarization of noble gases is described. The method and apparatus enable production, storage and usage of hyperpolarized noble gases for different purposes, including Magnetic Resonance Imaging of human and animal subjects. Magnetic imaging agents breathed into lungs can be observed by the radio waves of the MRI scanner and report back physical and functional information about lung's health and desease. The technique known as spin exchange optical pumping is used. Nuclear magnetic resonance is implemented to measure the polarization of hyperpolarized gas. The cells prepared and sealed under high vacuum after handling Alkali metals into the cell and filling with the 3He-N2 mixture. The cells could be refilled. The 3He reaches around 50% polarization in 5-15 hours.

VCAM-1-targeted core/shell nanoparticles for selective adhesion and delivery to endothelial cells with lipopolysaccharide-induced inflammation under shear flow and cellular magnetic resonance imaging in vitro.

Science.gov (United States)

Yang, Hong; Zhao, Fenglong; Li, Ying; Xu, Mingming; Li, Li; Wu, Chunhui; Miyoshi, Hirokazu; Liu, Yiyao

2013-01-01

Multifunctional nanomaterials with unique magnetic and luminescent properties have broad potential in biological applications. Because of the overexpression of vascular cell adhesion molecule-1 (VCAM-1) receptors in inflammatory endothelial cells as compared with normal endothelial cells, an anti-VCAM-1 monoclonal antibody can be used as a targeting ligand. Herein we describe the development of multifunctional core-shell Fe(3)O(4)@SiO2 nanoparticles with the ability to target inflammatory endothelial cells via VCAM-1, magnetism, and fluorescence imaging, with efficient magnetic resonance imaging contrast characteristics. Superparamagnetic iron oxide and fluorescein isothiocyanate (FITC) were loaded successfully inside the nanoparticle core and the silica shell, respectively, creating VCAM-1-targeted Fe(3)O(4)@SiO2(FITC) nanoparticles that were characterized by scanning electron microscopy, transmission electron microscopy, fluorescence spectrometry, zeta potential assay, and fluorescence microscopy. The VCAM-1-targeted Fe(3)O(4)@SiO2(FITC) nanoparticles typically had a diameter of 355 ± 37 nm, showed superparamagnetic behavior at room temperature, and cumulative and targeted adhesion to an inflammatory subline of human umbilical vein endothelial cells (HUVEC-CS) activated by lipopolysaccharide. Further, our data show that adhesion of VCAM-1-targeted Fe(3)O(4)@SiO2(FITC) nanoparticles to inflammatory HUVEC-CS depended on both shear stress and duration of exposure to stress. Analysis of internalization into HUVEC-CS showed that the efficiency of delivery of VCAM-1-targeted Fe(3)O(4)@SiO2(FITC) nanoparticles was also significantly greater than that of nontargeted Fe(3)O(4)@SiO2(FITC)-NH2 nanoparticles. Magnetic resonance images showed that the superparamagnetic iron oxide cores of the VCAM-1-targeted Fe(3)O(4)@SiO2(FITC) nanoparticles could also act as a contrast agent for magnetic resonance imaging. Taken together, the cumulative adhesion and uptake potential of

Magnetic deep eutectic solvents molecularly imprinted polymers for the selective recognition and separation of protein

International Nuclear Information System (INIS)

Liu, Yanjin; Wang, Yuzhi; Dai, Qingzhou; Zhou, Yigang

2016-01-01

A novel and facile magnetic deep eutectic solvents (DES) molecularly imprinted polymers (MIPs) for the selective recognition and separation of Bovine hemoglobin (BHb) was prepared. The new-type DES was adopted as the functional monomer which would bring molecular imprinted technology to a new direction. The amounts of DES were optimized. The obtained magnetic DES-MIPs were characterized with fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscope (FESEM), dynamic light scattering (DLS), elemental analysis and vibrating sample magnetometer (VSM). The results suggested that the imprinted polymers were successfully formed and possessed a charming magnetism. The maximum adsorption capability (Q_m_a_x) and dissociation constant (K_L) were analyzed by Langmuir isotherms (R"2 = 0.9983) and the value were estimated to be 175.44 mg/g and 0.035 mg/mL for the imprinted particles. And the imprinted particles showed a high imprinting factor of 4.77. In addition, the magnetic DES-MIPs presented outstanding recognition specificity and selectivity so that it can be utilized to separate template protein from the mixture of proteins and real samples. Last but not least, the combination of deep eutectic solvents and molecular imprinted technology in this paper provides a new perspective for the recognition and separation of proteins. - Highlights: • Combined green deep eutectic solvents (DES) and molecular imprinted technology in recognition and separation of proteins. • DES was adopted as a new-type functional monomer. • The obtained magnetic DES-MIPs can separate proteins rapidly by an external magnetic field. • Adsorption and selectivity properties were discussed.

Magnetic deep eutectic solvents molecularly imprinted polymers for the selective recognition and separation of protein

Energy Technology Data Exchange (ETDEWEB)

Liu, Yanjin [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Dai, Qingzhou [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Zhou, Yigang [Department of Microbiology, College of Basic Medicine, Central South University, Changsha, 410083 (China)

2016-09-14

A novel and facile magnetic deep eutectic solvents (DES) molecularly imprinted polymers (MIPs) for the selective recognition and separation of Bovine hemoglobin (BHb) was prepared. The new-type DES was adopted as the functional monomer which would bring molecular imprinted technology to a new direction. The amounts of DES were optimized. The obtained magnetic DES-MIPs were characterized with fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscope (FESEM), dynamic light scattering (DLS), elemental analysis and vibrating sample magnetometer (VSM). The results suggested that the imprinted polymers were successfully formed and possessed a charming magnetism. The maximum adsorption capability (Q{sub max}) and dissociation constant (K{sub L}) were analyzed by Langmuir isotherms (R{sup 2} = 0.9983) and the value were estimated to be 175.44 mg/g and 0.035 mg/mL for the imprinted particles. And the imprinted particles showed a high imprinting factor of 4.77. In addition, the magnetic DES-MIPs presented outstanding recognition specificity and selectivity so that it can be utilized to separate template protein from the mixture of proteins and real samples. Last but not least, the combination of deep eutectic solvents and molecular imprinted technology in this paper provides a new perspective for the recognition and separation of proteins. - Highlights: • Combined green deep eutectic solvents (DES) and molecular imprinted technology in recognition and separation of proteins. • DES was adopted as a new-type functional monomer. • The obtained magnetic DES-MIPs can separate proteins rapidly by an external magnetic field. • Adsorption and selectivity properties were discussed.

Recover vigorous cells of Magnetospirillum magneticum AMB-1 by capillary magnetic separation

Science.gov (United States)

Li, Jinhua; Ge, Xin; Zhang, Xiaokui; Chen, Guanjun; Pan, Yongxin

2010-07-01

Cultivable magnetotactic bacteria (MTB) in laboratory can provide sufficient samples for molecular microbiological and magnetic studies. However, a cold-stored MTB strain, such as Magnetospirillum magneticum AMB-1, often loses its ability to synthesize magnetosomes and consequently fails to sense the external magnetic field. It is therefore important to quickly recover vigorous bacteria cells that highly capable of magnetosome producing. In this study, a modified capillary magnetic separation system was designed to recover a deteriorating strain of Magnetospirillum magneticum AMB-1 that long-term cold-stored in a refrigerator. The results show that all cells obtained after a 3-cycle treatment were vigorous and had the ability to produce magnetosomes. Moreover, the 3rd-cycle recovered cells were able to form more magnetosome crystals. Compared with the colony formation method, this new method is time-saving, easily operated, and more efficient for recovering vigorous MTB cells.

In vitro toxicity test and searching the possibility of cancer cell line extermination by magnetic heating with using Fe3O4 magnetic fluid

International Nuclear Information System (INIS)

Pham Hoai Linh; Nguyen Chi Thuan; Nguyen Anh Tuan; Pham Van Thach; Nguyen Xuan Phuc; Le Van Hong; Tran Cong Yen; Nguyen Thi Quy; Hoang Thi My Nhung; Phi Thi Xuyen

2009-01-01

A Fe 3 O 4 based magnetic fluid with different concentrations ranged between 0.15 ng/cell to 10 ng/cell (nano gram/cell) was used in the in vitro toxicity test on several cancer cell lines, Sarcoma 180, HeLa and H358. It shows that the fluid with a concentration of Fe 3 O 4 below 1.2 ng/cell is completely non-toxic for these cell lines. Even through in the presence of the highest concentration of 10 ng/cell, the cell viability still reaches more than 60%. The magnetic fluid with Fe 3 O 4 concentration of about 0.1 ng/cell was also used to search ex-vivo the possibility of Sarcoma 180 extermination by magnetic heating with an AC field of 120Oe and 184 KHz. The result shows that after a heat treatment for 30 min., 40% of Sarcoma 180 cells was killed.

Low-magnetization magnetic microcapsules: A synergistic theranostic platform for remote cancer cells therapy and imaging

KAUST Repository

Zhang, Wei; Deng, Lin; Wang, Guangchao; Guo, Xianrong; Li, Qiujin; Zhang, Jianfei; Khashab, Niveen M.

2014-01-01

Multifunctional magnetic microcapsules (MMCs) for the combined cancer cells hyperthermia and chemotherapy in addition to MR imaging are successfully developed. A classical layer-by-layer technique of oppositely charged polyelectrolytes (poly

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.

Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging

International Nuclear Information System (INIS)

Kale, Anup; Yadav, Prasad; Gholap, Haribhau; Jog, J P; Ogale, Satishchandra; Kale, Sonia; Shastry, Padma; Pasricha, Renu; Lefez, Benoit; Hannoyer, Beatrice

2011-01-01

A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

Sickle Cell: A Selected Resource Bibliography.

Science.gov (United States)

National Center for Education in Maternal and Child Health, Washington, DC.

This annotated, selective bibliography lists the following types of educational and informational material on both sickle cell disease and trait: (1) professional education materials; (2) fact sheets, pamphlets, and brochures; and (3) audiovisual material. A selected list of references is provided for the following topic areas: (1) genetic…

Magnetically modified bacterial cellulose: A promising carrier for immobilization of affinity ligands, enzymes, and cells

Energy Technology Data Exchange (ETDEWEB)

Baldikova, Eva [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Pospiskova, Kristyna [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Ladakis, Dimitrios; Kookos, Ioannis K. [Department of Chemical Engineering, University of Patras, 26504 Patras, Rio (Greece); Koutinas, Apostolis A. [Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, Athens 11855 (Greece); Safarikova, Mirka [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Safarik, Ivo, E-mail: safarik@nh.cas.cz [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

2017-02-01

Bacterial cellulose (BC) produced by Komagataeibacter sucrofermentans was magnetically modified using perchloric acid stabilized magnetic fluid. Magnetic bacterial cellulose (MBC) was used as a carrier for the immobilization of affinity ligands, enzymes and cells. MBC with immobilized reactive copper phthalocyanine dye was an efficient adsorbent for crystal violet removal; the maximum adsorption capacity was 388 mg/g. Kinetic and thermodynamic parameters were also determined. Model biocatalysts, namely bovine pancreas trypsin and Saccharomyces cerevisiae cells were immobilized on MBC using several strategies including adsorption with subsequent cross-linking with glutaraldehyde and covalent binding on previously activated MBC using sodium periodate or 1,4-butanediol diglycidyl ether. Immobilized yeast cells retained approximately 90% of their initial activity after 6 repeated cycles of sucrose solution hydrolysis. Trypsin covalently bound after MBC periodate activation was very stable during operational stability testing; it could be repeatedly used for ten cycles of low molecular weight substrate hydrolysis without loss of its initial activity. - Highlights: • Bacterial cellulose was magnetically modified with magnetic fluid. • Magnetic cellulose is an efficient carrier for affinity ligands. • Enzymes and cells can be efficiently immobilized to magnetic cellulose.

A Novel Hybrid Actuator Driven Magnetically in the Bi-Cell PEM Fuel Cell Stack

Directory of Open Access Journals (Sweden)

Hsiaokang Ma

2017-10-01

Full Text Available This study develops an air breathing pump driven by a piezoelectric actuator for a proton exchange membrane fuel cell (PEMFC stack. Permanent magnets are combined with a piezoelectric actuator to drive three air breathing pumps using magnetic force. This design enables the pump to provide a sufficient amount of air simultaneously to six cathode flow field plates in a stack of three “bi-cell PZTmag–PEMFCs”. When both the PZTmag and the PDMSmag had a magnet with a 6-mm diameter and 1-mm thickness, a maximum amplitude of 87 μm was generated at 0.03 W of power under operating conditions of 70 Hz and 40 V. In computational fluid dynamics (CFD, when the nozzle and the diffuser of an air breathing pump have an aspect ratio of 13.13, air flow distributes uniformly inside the pump, thus allowing for uniform transmission of oxygen to the membrane electrode assembly. This aspect ratio was applied to the bi-cell PZTmag–PEMFC stack and yielded a maximum net power flux of 0.1925 W·cm−2, 20% higher than that reported in a previous study (Ma, 2013, with 68% and 76% less volume and weight, respectively.

Acceleration of gene transfection efficiency in neuroblastoma cells through polyethyleneimine/poly(methyl methacrylate core-shell magnetic nanoparticles

Directory of Open Access Journals (Sweden)

Tencomnao T

2012-06-01

Full Text Available Tewin Tencomnao,1,* Kewalin Klangthong,2,* Nuttaporn Pimpha,3 Saowaluk Chaleawlert-umpon,3 Somsak Saesoo,3 Noppawan Woramongkolchai,3 Nattika Saengkrit,31Center for Excellence in Omics-Nano Medical Technology Development Project, 2Graduate Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 3National Nanotechnology Center, National Science and Technology Development Agency, Pathumthani, Thailand*Both authors contributed equally to this workBackground: The purpose of this study was to demonstrate the potential of magnetic poly(methyl methacrylate (PMMA core/polyethyleneimine (PEI shell (mag-PEI nanoparticles, which possess high saturation magnetization for gene delivery. By using mag-PEI nanoparticles as a gene carrier, this study focused on evaluation of transfection efficiency under magnetic induction. The potential role of this newly synthesized nanosphere for therapeutic delivery of the tryptophan hydroxylase-2 (TPH-2 gene was also investigated in cultured neuronal LAN-5 cells.Methods: The mag-PEI nanoparticles were prepared by one-step emulsifier-free emulsion polymerization, generating highly loaded and monodispersed magnetic polymeric nanoparticles bearing an amine group. The physicochemical properties of the mag-PEI nanoparticles and DNA-bound mag-PEI nanoparticles were investigated using the gel retardation assay, atomic force microscopy, and zeta size measurements. The gene transfection efficiencies of mag-PEI nanoparticles were evaluated at different transfection times. Confocal laser scanning microscopy confirmed intracellular uptake of the magnetoplex. The optimal conditions for transfection of TPH-2 were selected for therapeutic gene transfection. We isolated the TPH-2 gene from the total RNA of the human medulla oblongata and cloned it into an expression vector. The plasmid containing TPH-2 was subsequently bound onto the

Selection of D-Alanine-Tolerant Rice Cells

OpenAIRE

Hisashi, Manabe; Koji, Ohira; Aizu Junior College of Fukushima Prefecture; Department of Agricultural Chemistry, Faculty of Agriculture, Tohoku University

1984-01-01

By repeating subculture of rice cells (parent cells) in a D-alanine containing medium, we could select rice cells which grew well in the D-alanine medium. The D-alanine-tolerant cells absorbed a fairly small amount of D-alanine from the medium and did not accumulate much D-alanine in the cells. Aggregation of D-alanine-tolerant cells was greater than that of parent cells. D-Alanine metabolism of D-alanine.-tolerant cells did not increase in comparison with parent cells.

The magnetic introduction of magnetite nanoparticles into live cells for radiosensibility enhancement

Energy Technology Data Exchange (ETDEWEB)

Yurenya, Anton Y., E-mail: antonyurenya@gmail.com [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Faculty of Physics, Lomonosov Moscow State University, Moscow (Russian Federation); Polikarpov, Mikhail A. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Chukalova, Aynur A. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Moscow (Russian Federation); Moskaleva, Elizaveta Y.; Taldenkov, Alexander N. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Panchenko, Vladislav Y. [National Research Center “Kurchatov Institute”, Moscow (Russian Federation); Faculty of Physics, Lomonosov Moscow State University, Moscow (Russian Federation)

2017-04-01

Earlier we proposed a new radiotherapy enhancement method that entails the administration of {sup 57}Fe iron-oxide nanoparticles into the cells . Within this work we were prompt to investigate the capability of iron oxide nanoparticles with monolayer coating to penetrate into live cells. Magnetite particle samples were synthesized and stabilized with HCl or citric acid. The cells were incubated in the presence of nanoparticles for 1 h, washed and dried. To distinguish inside-cell particles from outside ones a set of experiments with low temperature incubation was carried out. Several cell samples were prepared in the presence of an external magnetic field in order to study the possibility of the nanoparticle uptake enhancement. To evaluate the amount of particles in each cell sample we used a SQUID-magnetometer. The nanoparticle suspension with HCl stabilization turned to be inadequate for intracellular introduction. Approximately 2·10{sup 5} particles with citric acid covering conjugated with each cell after incubation at normal conditions. An application of an external magnetic field increased this amount up to 10{sup 7} particles/cell. Most probably much of these particles penetrated into cells. - Highlights: • Uncoated magnetite nanoparticle suspension is unusable for intracellular introduction. • Magnetite particles stabilized with citric acid penetrate into cells via endocytosis. • An application of a magnetic field enhances cellular uptake of magnetite particles. • The amount of particles in cell samples can be evaluated with a SQUID-magnetometer.

Using injection molding and reversible bonding for easy fabrication of magnetic cell trapping and sorting devices

Energy Technology Data Exchange (ETDEWEB)

Royet, David; Hériveaux, Yoann; Marchalot, Julien; Scorretti, Riccardo [Univ Lyon, ECL, UCB Lyon1, CNRS, Ampere, F-69134 Ecully (France); Dias, André; Dempsey, Nora M. [Univ. Grenoble Alpes - CNRS, Inst Neel, F-38042 Grenoble (France); Bonfim, Marlio [Universidade Federal do Paraná, DELT, Curitiba (Brazil); Simonet, Pascal; Frénéa-Robin, Marie [Univ Lyon, ECL, UCB Lyon1, CNRS, Ampere, F-69134 Ecully (France)

2017-04-01

Magnetism and microfluidics are two key elements for the development of inexpensive and reliable tools dedicated to high-throughput biological analysis and providing a large panel of applications in domains ranging from fundamental biology to medical diagnostics. In this work, we introduce a simple protocol, relying on injection molding and reversible bonding for fabrication of magnetic cell trapping and sorting devices using only standard soft-lithography equipment. Magnetic strips or grids made of Polydimethylsiloxane (PDMS) doped with hard (NdFeB) or soft (carbonyl iron) magnetic powders were integrated at the bottom of whole PDMS chips. Preliminary results show the effective deviation/trapping of magnetic beads or magnetically-labeled bacteria as the sample flows through the microchannel, proving the potential of this rapid prototyping approach for easy fabrication of magnetic cell sorters. - Highlights: • Soft and hard magnetic PDMS composites were microstructured by injection molding. • Tunable or autonomous magnetic microdevices can be fabricated using this approach. • Continuous-flow bacterial cell trapping and deviation were demonstrated.

Using injection molding and reversible bonding for easy fabrication of magnetic cell trapping and sorting devices

International Nuclear Information System (INIS)

Royet, David; Hériveaux, Yoann; Marchalot, Julien; Scorretti, Riccardo; Dias, André; Dempsey, Nora M.; Bonfim, Marlio; Simonet, Pascal; Frénéa-Robin, Marie

2017-01-01

Magnetism and microfluidics are two key elements for the development of inexpensive and reliable tools dedicated to high-throughput biological analysis and providing a large panel of applications in domains ranging from fundamental biology to medical diagnostics. In this work, we introduce a simple protocol, relying on injection molding and reversible bonding for fabrication of magnetic cell trapping and sorting devices using only standard soft-lithography equipment. Magnetic strips or grids made of Polydimethylsiloxane (PDMS) doped with hard (NdFeB) or soft (carbonyl iron) magnetic powders were integrated at the bottom of whole PDMS chips. Preliminary results show the effective deviation/trapping of magnetic beads or magnetically-labeled bacteria as the sample flows through the microchannel, proving the potential of this rapid prototyping approach for easy fabrication of magnetic cell sorters. - Highlights: • Soft and hard magnetic PDMS composites were microstructured by injection molding. • Tunable or autonomous magnetic microdevices can be fabricated using this approach. • Continuous-flow bacterial cell trapping and deviation were demonstrated.

Towards The Generation of Functionalized Magnetic Nanowires to Target Leukemic Cells

KAUST Repository

Alsharif, Nouf

2016-04-01

In recent years, magnetic nanowires (NWs) have been widely used for their therapeutic potential in biomedical applications. The use of iron (Fe) NWs combines two important properties, biocompatibility and remote manipulation by magnetic fields. In addition the NWs can be coated and functionalized to target cells of interest and, upon exposure to an alternating magnetic field, have been shown to induce cell death on several types of adherent cells, including several cancer cell types. For suspension cells, however, using these NWs has been much less effective primarily due to the free-floating nature of the cells minimizing the interaction between them and the NWs. Leukemic cells express higher levels of the cell surface marker CD44 (Braumüller, Gansauge, Ramadani, & Gansauge, 2000), compared to normal blood cells. The goal of this study was to functionalize Fe NWs with a specific monoclonal antibody towards CD44 in order to target leukemic cells (HL-60 cells). This approach is expected to increase the probability of a specific binding to occur between HL-60 cells and Fe NWs. Fe NWs were fabricated with an average diameter of 30-40 nm and a length around 3-4 μm. Then, they were coated with both 3-Aminopropyl-triethoxysilane and bovine serum albumin (BSA) in order to conjugate them with an anti-CD44 antibody (i.e. anti-CD44-iron NWs). The antibody interacts with the amine group in the BSA via the 1-Ethyl-3-3-dimethylaminopropyl-carbodiimide and N-Hydroxysuccinimide coupling. The NWs functionalization was confirmed using a number of approaches including: infrared spectroscopy, Nanodrop to measure the concentration of CD44 antibody, as well as fluorescent-labeled secondary antibody staining to detect the primary CD44 antibody. To confirm that the anti-CD44-iron NWs and bare Fe NWs, in the absence of a magnetic field, were not toxic to HL-60 cells, cytotoxicity assays using XTT (2,3-Bis-2-Methoxy-4-Nitro-5-Sulfophenyl-2H-Tetrazolium-5-Carboxanilide) were performed and

Magnetic targeting as a strategy to enhance therapeutic effects of mesenchymal stromal cells.

Science.gov (United States)

Silva, Luisa H A; Cruz, Fernanda F; Morales, Marcelo M; Weiss, Daniel J; Rocco, Patricia R M

2017-03-09

Mesenchymal stromal cells (MSCs) have been extensively investigated in the field of regenerative medicine. It is known that the success of MSC-based therapies depends primarily on effective cell delivery to the target site where they will secrete vesicles and soluble factors with immunomodulatory and potentially reparative properties. However, some lesions are located in sites that are difficult to access, such as the heart, spinal cord, and joints. Additionally, low MSC retention at target sites makes cell therapy short-lasting and, therefore, less effective. In this context, the magnetic targeting technique has emerged as a new strategy to aid delivery, increase retention, and enhance the effects of MSCs. This approach uses magnetic nanoparticles to magnetize MSCs and static magnetic fields to guide them in vivo, thus promoting more focused, effective, and lasting retention of MSCs at the target site. In the present review, we discuss the magnetic targeting technique, its principles, and the materials most commonly used; we also discuss its potential for MSC enhancement, and safety concerns that should be addressed before it can be applied in clinical practice.

Modulation of monocytic leukemia cell function and survival by high gradient magnetic fields and mathematical modeling studies.

Science.gov (United States)

Zablotskii, Vitalii; Syrovets, Tatiana; Schmidt, Zoe W; Dejneka, Alexandr; Simmet, Thomas

2014-03-01

The influence of spatially modulated high gradient magnetic fields on cellular functions of human THP-1 leukemia cells is studied. We demonstrate that arrays of high-gradient micrometer-sized magnets induce i) cell swelling, ii) prolonged increased ROS production, and iii) inhibit cell proliferation, and iv) elicit apoptosis of THP-1 monocytic leukemia cells in the absence of chemical or biological agents. Mathematical modeling indicates that mechanical stress exerted on the cells by high magnetic gradient forces is responsible for triggering cell swelling and formation of reactive oxygen species followed by apoptosis. We discuss physical aspects of controlling cell functions by focused magnetic gradient forces, i.e. by a noninvasive and nondestructive physical approach. Copyright © 2014 Elsevier Ltd. All rights reserved.

Does Magnetic Field Affect Malaria Parasite Replication in Human Red Blood Cells?

Science.gov (United States)

Chanturiya, Alexandr N.; Glushakova, Svetlana; Yin, Dan; Zimmerberg, Joshua

2004-01-01

Digestion of red blood cell (RBC) hemoglobin by the malaria parasite results in the formation of paramagnetic hemazoin crystals inside the parasite body. A number of reports suggest that magnetic field interaction with hamazoin crystals significantly reduces the number of infected cells in culture, and thus magnetic field can be used to combat malaria. We studies the effects of magnetic filed on the Plasmodium falciparum asexual life cycle inside RBCs under various experimental conditions. No effect was found during prolonged exposure of infected RBCs to constant magnetic fields up to 6000 Gauss. Infected RBCs were also exposed, under temperature-controlled conditions, to oscillating magnetic fields with frequencies in the range of 500-20000 kHz, and field strength 30-600 Gauss. This exposure often changed the proportion of different parasite stages in treated culture compared to controls. However, no significant effect on parasitemia was observed in treated cultures. This result indicates that the magnetic field effect on Plasmodium falciparum is negligible, or that hypothetical negative and positive effects on different stages within one 48-hour compensate each other.

Design and development of a magnetic device for mesenchymal stem cell retaining in deep targets

Science.gov (United States)

Banis, G. C.

2017-12-01

This paper focuses on the retaining of mesenchymal stem cells in blood flow conditions using the appropriate magnetic field. Mesenchymal stem cells can be tagged with magnetic nanoparticles and thus, they can be manipulated from distance, through the application of an external magnetic field. In this paper the case of kidney as target of the therapy is being studied.

Static high-gradient magnetic fields affect the functionality of monocytic cells

Czech Academy of Sciences Publication Activity Database

Syrovets, T.; Schmidt, Z.; Buechele, B.; Zablotskyy, Vitaliy A.; Dejneka, Alexandr; Dempsey, N.; Simmet, T.

2014-01-01

Roč. 28, č. 1 (2014), s. 1-2 ISSN 0892-6638 Institutional support: RVO:68378271 Keywords : static high-gradient * magnet ic fields * affect the functionality * monocytic cells Subject RIV: BM - Solid Matter Physics ; Magnet ism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.)

Fe3O4/BSA particles induce osteogenic differentiation of mesenchymal stem cells under static magnetic field.

Science.gov (United States)

Jiang, Pengfei; Zhang, Yixian; Zhu, Chaonan; Zhang, Wenjing; Mao, Zhengwei; Gao, Changyou

2016-12-01

Differentiation of stem cells is influenced by many factors, yet uptake of the magnetic particles with or without magnetic field is rarely tackled. In this study, iron oxide nanoparticles-loaded bovine serum albumin (BSA) (Fe 3 O 4 /BSA) particles were prepared, which showed a spherical morphology with a diameter below 200 nm, negatively charged surface, and tunable magnetic property. The particles could be internalized into bone marrow mesenchymal stem cells (MSCs), and their release from the cells was significantly retarded under external magnetic field, resulting in almost twice intracellular amount of the particles within 21 d compared to that of the magnetic field free control. Uptake of the Fe 3 O 4 /BSA particles enhanced significantly the osteogenic differentiation of MSCs under a static magnetic field, as evidenced by elevated alkaline phosphatase (ALP) activity, calcium deposition, and expressions of collagen type I and osteocalcin at both mRNA and protein levels. Therefore, uptake of the Fe 3 O 4 /BSA particles brings significant influence on the differentiation of MSCs under magnetic field, and thereby should be paid great attention for practical applications. Differentiation of stem cells is influenced by many factors, yet uptake of the magnetic particles with or without magnetic field is rarely tackled. In this study, iron oxide nanoparticles-loaded bovine serum albumin (BSA) (Fe 3 O 4 /BSA) particles with a diameter below 200nm, negatively charged surface, tunable Fe 3 O 4 content and subsequently adjustable magnetic property were prepared. The particles could be internalized into bone marrow mesenchymal stem cells (MSCs), and their release from the cells was significantly retarded under external magnetic field. Uptake of the Fe 3 O 4 /BSA particles enhanced significantly the osteogenic differentiation of MSCs under a constant static magnetic field, while the magnetic particles and external magnetic field alone do not influence significantly the

Magnetically Driven Micromachines Created by Two-Photon Microfabrication and Selective Electroless Magnetite Plating for Lab-on-a-Chip Applications

Directory of Open Access Journals (Sweden)

Tommaso Zandrini

2017-01-01

Full Text Available We propose a novel method to fabricate three-dimensional magnetic microparts, which can be integrated in functional microfluidic networks and lab-on-a-chip devices, by the combination of two-photon microfabrication and selective electroless plating. In our experiments, magnetic microparts could be successfully fabricated by optimizing various experimental conditions of electroless plating. In addition, energy dispersive X-ray spectrometry (EDS clarified that iron oxide nanoparticles were deposited onto the polymeric microstructure site-selectively. We also fabricated magnetic microrotors which could smoothly rotate using common laboratory equipment. Since such magnetic microparts can be remotely driven with an external magnetic field, our fabrication process can be applied to functional lab-on-a-chip devices for analytical and biological applications.

Magnetic field enhancement of organic photovoltaic cells performance.

Science.gov (United States)

Oviedo-Casado, S; Urbina, A; Prior, J

2017-06-27

Charge separation is a critical process for achieving high efficiencies in organic photovoltaic cells. The initial tightly bound excitonic electron-hole pair has to dissociate fast enough in order to avoid photocurrent generation and thus power conversion efficiency loss via geminate recombination. Such process takes place assisted by transitional states that lie between the initial exciton and the free charge state. Due to spin conservation rules these intermediate charge transfer states typically have singlet character. Here we propose a donor-acceptor model for a generic organic photovoltaic cell in which the process of charge separation is modulated by a magnetic field which tunes the energy levels. The impact of a magnetic field is to intensify the generation of charge transfer states with triplet character via inter-system crossing. As the ground state of the system has singlet character, triplet states are recombination-protected, thus leading to a higher probability of successful charge separation. Using the open quantum systems formalism we demonstrate that the population of triplet charge transfer states grows in the presence of a magnetic field, and discuss the impact on carrier population and hence photocurrent, highlighting its potential as a tool for research on charge transfer kinetics in this complex systems.

Elucidating the Function of Penetratin and a Static Magnetic Field in Cellular Uptake of Magnetic Nanoparticles

Directory of Open Access Journals (Sweden)

David Stirling

2013-02-01

Full Text Available Nanotechnology plays an increasingly important role in the biomedical arena. In particular, magnetic nanoparticles (mNPs have become important tools in molecular diagnostics, in vivo imaging and improved treatment of disease, with the ultimate aim of producing a more theranostic approach. Due to their small sizes, the nanoparticles can cross most of the biological barriers such as the blood vessels and the blood brain barrier, thus providing ubiquitous access to most tissues. In all biomedical applications maximum nanoparticle uptake into cells is required. Two promising methods employed to this end include functionalization of mNPs with cell-penetrating peptides to promote efficient translocation of cargo into the cell and the use of external magnetic fields for enhanced delivery. This study aimed to compare the effect of both penetratin and a static magnetic field with regards to the cellular uptake of 200 nm magnetic NPs and determine the route of uptake by both methods. Results demonstrated that both techniques increased particle uptake, with penetratin proving more cell specific. Clathrin- medicated endocytosis appeared to be responsible for uptake as shown via PCR and western blot, with Pitstop 2 (known to selectively block clathrin formation blocking particle uptake. Interestingly, it was further shown that a magnetic field was able to reverse or overcome the blocking, suggesting an alternative route of uptake.

Targeting of phage particles towards endothelial cells by antibodies selected through a multi-parameter selection strategy.

Science.gov (United States)

Mandrup, Ole A; Lykkemark, Simon; Kristensen, Peter

2017-02-10

One of the hallmarks of cancer is sustained angiogenesis. Here, normal endothelial cells are activated, and their formation of new blood vessels leads to continued tumour growth. An improved patient condition is often observed when angiogenesis is prevented or normalized through targeting of these genomically stable endothelial cells. However, intracellular targets constitute a challenge in therapy, as the agents modulating these targets have to be delivered and internalized specifically to the endothelial cells. Selection of antibodies binding specifically to certain cell types is well established. It is nonetheless a challenge to ensure that the binding of antibodies to the target cell will mediate internalization. Previously selection of such antibodies has been performed targeting cancer cell lines; most often using either monovalent display or polyvalent display. In this article, we describe selections that isolate internalizing antibodies by sequential combining monovalent and polyvalent display using two types of helper phages, one which increases display valence and one which reduces background. One of the selected antibodies was found to mediate internalization into human endothelial cells, although our results confirms that the single stranded nature of the DNA packaged into phage particles may limit applications aimed at targeting nucleic acids in mammalian cells.

Splenic red pulp macrophages are intrinsically superparamagnetic and contaminate magnetic cell isolates.

Science.gov (United States)

Franken, Lars; Klein, Marika; Spasova, Marina; Elsukova, Anna; Wiedwald, Ulf; Welz, Meike; Knolle, Percy; Farle, Michael; Limmer, Andreas; Kurts, Christian

2015-08-11

A main function of splenic red pulp macrophages is the degradation of damaged or aged erythrocytes. Here we show that these macrophages accumulate ferrimagnetic iron oxides that render them intrinsically superparamagnetic. Consequently, these cells routinely contaminate splenic cell isolates obtained with the use of MCS, a technique that has been widely used in immunological research for decades. These contaminations can profoundly alter experimental results. In mice deficient for the transcription factor SpiC, which lack red pulp macrophages, liver Kupffer cells take over the task of erythrocyte degradation and become superparamagnetic. We describe a simple additional magnetic separation step that avoids this problem and substantially improves purity of magnetic cell isolates from the spleen.

Engineered core-shell magnetic nanoparticle for MR dual-modal tracking and safe magnetic manipulation of ependymal cells in live rodents

Science.gov (United States)

Peng, Yung-Kang; Lui, Cathy N. P.; Chen, Yu-Wei; Chou, Shang-Wei; Chou, Pi-Tai; Yung, Ken K. L.; Edman Tsang, S. C.

2018-01-01

Tagging recognition group(s) on superparamagnetic iron oxide is known to aid localisation (imaging), stimulation and separation of biological entities using magnetic resonance imaging (MRI) and magnetic agitation/separation (MAS) techniques. Despite the wide applicability of iron oxide nanoparticles in T 2-weighted MRI and MAS, the quality of the images and safe manipulation of the exceptionally delicate neural cells in a live brain are currently the key challenges. Here, we demonstrate the engineered manganese oxide clusters-iron oxide core-shell nanoparticle as an MR dual-modal contrast agent for neural stem cells (NSCs) imaging and magnetic manipulation in live rodents. As a result, using this engineered nanoparticle and associated technologies, identification, stimulation and transportation of labelled potentially multipotent NSCs from a specific location of a live brain to another by magnetic means for self-healing therapy can therefore be made possible.

Photothermal therapy of cancer cells using magnetic carbon nanoparticles

Science.gov (United States)

Vardarajan, V.; Gu, L.; Kanneganti, A.; Mohanty, S. K.; Koymen, A. R.

2011-03-01

Photothermal therapy offers a solution for the destruction of cancer cells without significant collateral damage to otherwise healthy cells. Several attempts are underway in using carbon nanoparticles (CNPs) and nanotubes due to their excellent absorption properties in the near-infrared spectrum of biological window. However, minimizing the required number of injected nanoparticles, to ensure minimal cytotoxicity, is a major challenge. We report on the introduction of magnetic carbon nanoparticles (MCNPs) onto cancer cells, localizing them in a desired region by applying an external magnetic field and irradiating them with a near-infrared laser beam. The MCNPs were prepared in Benzene, using an electric plasma discharge, generated in the cavitation field of an ultrasonic horn. The CNPs were made ferromagnetic by use of Fe-electrodes to dope the CNPs, as confirmed by magnetometry. Transmission electron microscopy measurements showed the size distribution of these MCNPs to be in the range of 5-10 nm. For photothermal irradiation, a tunable continuous wave Ti: Sapphire laser beam was weakly focused on to the cell monolayer under an inverted fluorescence microscope. The response of different cell types to photothermal irradiation was investigated. Cell death in the presence of both MCNPs and laser beam was confirmed by morphological changes and propidium iodide fluorescence inclusion assay. The results of our study suggest that MCNP based photothermal therapy is a promising approach to remotely guide photothermal therapy.

Tracking of adipose tissue-derived progenitor cells using two magnetic nanoparticle types

Energy Technology Data Exchange (ETDEWEB)

Kasten, Annika; Siegmund, Birte J. [Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, Rostock University Medical Center, Schillingallee 35 D-18057 Rostock (Germany); Grüttner, Cordula [Micromod Partikeltechnologie GmbH, Warnemünde, D-18115 Rostock (Germany); Kühn, Jens-Peter [Department of Radiology and Neuroradiology, Greifswald University Medical Center, D-17475 Greifswald (Germany); Frerich, Bernhard, E-mail: bernhard.frerich@med.uni-rostock.de [Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, Rostock University Medical Center, Schillingallee 35 D-18057 Rostock (Germany)

2015-04-15

Magnetic resonance imaging (MRI) is to be considered as an emerging detection technique for cell tracking experiments to evaluate the fate of transplanted progenitor cells and develop successful cell therapies for tissue engineering. Adipose tissue engineering using adipose tissue-derived progenitor cells has been advocated for the cure of soft tissue defects or for persistent soft tissue augmentation. Adipose tissue-derived progenitor cells were differentiated into the adipogenic lineage and labeled with two different types of magnetic iron oxide nanoparticles in varying concentrations which resulted in a concentration-dependent reduction of gene expression of adipogenic differentiation markers, adiponectin and fatty acid-binding protein 4 (FABP4), whereas the metabolic activity was not altered. As a result, only low nanoparticle concentrations for labeling were used for in vivo experiments. Cells were seeded onto collagen scaffolds and subcutaneously implanted into severe combined immunodeficient (SCID) mice. At 24 h as well as 28 days after implantation, MRI analyses were performed visualizing nanoparticle-labeled cells using T2-weighted sequences. The quantification of absolute volume of the scaffolds revealed a decrease of volume over time in all experimental groups. The distribution of nanoparticle-labeled cells within the scaffolds varied likewise over time. - Highlights: • Adipose tissue-derived stem cells (ASC) were labeled with magnetic iron oxide nanoparticles. • Nanoparticles influenced the adipogenic differentiation of ASC. • Labeled cells were seeded onto collagen scaffolds and implanted in SCID mice. • Nanoparticle-labeled cells were visualized in vivo using T2-weighted sequences. • Volume of collagen scaffolds was decreased over time after implantation.

Tracking of adipose tissue-derived progenitor cells using two magnetic nanoparticle types

International Nuclear Information System (INIS)

Kasten, Annika; Siegmund, Birte J.; Grüttner, Cordula; Kühn, Jens-Peter; Frerich, Bernhard

2015-01-01

Magnetic resonance imaging (MRI) is to be considered as an emerging detection technique for cell tracking experiments to evaluate the fate of transplanted progenitor cells and develop successful cell therapies for tissue engineering. Adipose tissue engineering using adipose tissue-derived progenitor cells has been advocated for the cure of soft tissue defects or for persistent soft tissue augmentation. Adipose tissue-derived progenitor cells were differentiated into the adipogenic lineage and labeled with two different types of magnetic iron oxide nanoparticles in varying concentrations which resulted in a concentration-dependent reduction of gene expression of adipogenic differentiation markers, adiponectin and fatty acid-binding protein 4 (FABP4), whereas the metabolic activity was not altered. As a result, only low nanoparticle concentrations for labeling were used for in vivo experiments. Cells were seeded onto collagen scaffolds and subcutaneously implanted into severe combined immunodeficient (SCID) mice. At 24 h as well as 28 days after implantation, MRI analyses were performed visualizing nanoparticle-labeled cells using T2-weighted sequences. The quantification of absolute volume of the scaffolds revealed a decrease of volume over time in all experimental groups. The distribution of nanoparticle-labeled cells within the scaffolds varied likewise over time. - Highlights: • Adipose tissue-derived stem cells (ASC) were labeled with magnetic iron oxide nanoparticles. • Nanoparticles influenced the adipogenic differentiation of ASC. • Labeled cells were seeded onto collagen scaffolds and implanted in SCID mice. • Nanoparticle-labeled cells were visualized in vivo using T2-weighted sequences. • Volume of collagen scaffolds was decreased over time after implantation

Particle-in-cell simulations of plasma opening switch with external magnetic field

International Nuclear Information System (INIS)

Chen Yulan; Zeng Zhengzhong; Sun Fengju

2003-01-01

Fully electromagnetic particle-in-cell simulations are performed to study the effects of an external magnetic field on coaxial plasma opening switch (POS). The simulation results show that POS opening performance can be significantly improved only when external longitudinal magnetic field coils are placed at the cathode side, and an additional azimuthal magnetic field is effective whether the central electrode is of positive or negative polarity. Voltage multiplication coefficient K rises with the additional magnetic field increasing till the electron current is completely magnetically insulated during the opening of POS

Magnetization Dynamics in Two Novel Current-Driven Spintronic Memory Cell Structures

KAUST Repository

Velazquez-Rizo, Martin

2017-01-01

In this work, two new spintronic memory cell structures are proposed. The first cell uses the diffusion of polarized spins into ferromagnets with perpendicular anisotropy to tilt their magnetization followed by their dipolar coupling to a fixed

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

Science.gov (United States)

Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

2015-08-18

The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

Building Cell Selectivity into CPP-Mediated Strategies

Directory of Open Access Journals (Sweden)

Irene Martín

2010-05-01

Full Text Available There is a pressing need for more effective and selective therapies for cancer and other diseases. Consequently, much effort is being devoted to the development of alternative experimental approaches based on selective systems, which are designed to be specifically directed against target cells. In addition, a large number of highly potent therapeutic molecules are being discovered. However, they do not reach clinical trials because of their low delivery, poor specificity or their incapacity to bypass the plasma membrane. Cell-penetrating peptides (CPPs are an open door for cell-impermeable compounds to reach intracellular targets. Putting all these together, research is sailing in the direction of the design of systems with the capacity to transport new drugs into a target cell. Some CPPs show cell type specificity while others require modifications or form part of more sophisticated drug delivery systems. In this review article we summarize several strategies for directed drug delivery involving CPPs that have been reported in the literature.

Magnetic field-induced modification of selection rules for Rb D 2 line monitored by selective reflection from a vapor nanocell

Science.gov (United States)

Klinger, Emmanuel; Sargsyan, Armen; Tonoyan, Ara; Hakhumyan, Grant; Papoyan, Aram; Leroy, Claude; Sarkisyan, David

2017-08-01

Magnetic field-induced giant modification of the probabilities of five transitions of 5S1 / 2,Fg = 2 → 5P3 / 2,Fe = 4 of 85Rb and three transitions of 5S1 / 2,Fg = 1 → 5P3 / 2,Fe = 3 of 87Rb forbidden by selection rules for zero magnetic field has been observed experimentally and described theoretically for the first time. For the case of excitation with circularly-polarized (σ+) laser radiation, the probability of Fg = 2,mF = - 2 → Fe = 4,mF = - 1 transition becomes the largest among the seventeen transitions of 85Rb Fg = 2 → Fe = 1,2,3,4 group, and the probability of Fg = 1, mF = - 1 → Fe = 3,mF = 0 transition becomes the largest among the nine transitions of 87Rb Fg = 1 → Fe = 0,1,2,3 group, in a wide range of magnetic field 200-1000 G. Complete frequency separation of individual Zeeman components was obtained by implementation of derivative selective reflection technique with a 300 nm-thick nanocell filled with Rb, allowing formation of narrow optical resonances. Possible applications are addressed. The theoretical model is well consistent with the experimental results.

Managing magnetic nanoparticle aggregation and cellular uptake: a precondition for efficient stem-cell differentiation and MRI tracking.

Science.gov (United States)

Fayol, Delphine; Luciani, Nathalie; Lartigue, Lenaic; Gazeau, Florence; Wilhelm, Claire

2013-02-01

The labeling of stem cells with iron oxide nanoparticles is increasingly used to enable MRI cell tracking and magnetic cell manipulation, stimulating the fields of tissue engineering and cell therapy. However, the impact of magnetic labeling on stem-cell differentiation is still controversial. One compromising factor for successful differentiation may arise from early interactions of nanoparticles with cells during the labeling procedure. It is hypothesized that the lack of control over nanoparticle colloidal stability in biological media may lead to undesirable nanoparticle localization, overestimation of cellular uptake, misleading MRI cell tracking, and further impairment of differentiation. Herein a method is described for labeling mesenchymal stem cells (MSC), in which the physical state of citrate-coated nanoparticles (dispersed versus aggregated) can be kinetically tuned through electrostatic and magnetic triggers, as monitored by diffusion light scattering in the extracellular medium and by optical and electronic microscopy in cells. A set of statistical cell-by-cell measurements (flow cytometry, single-cell magnetophoresis, and high-resolution MRI cellular detection) is used to independently quantify the nanoparticle cell uptake and the effects of nanoparticle aggregation. Such aggregation confounds MRI cell detection as well as global iron quantification and has adverse effects on chondrogenetic differentiation. Magnetic labeling conditions with perfectly stable nanoparticles-suitable for obtaining differentiation-capable magnetic stem cells for use in cell therapy-are subsequently identified. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-magnetization magnetic microcapsules: A synergistic theranostic platform for remote cancer cells therapy and imaging

KAUST Repository

Zhang, Wei

2014-04-02

Multifunctional magnetic microcapsules (MMCs) for the combined cancer cells hyperthermia and chemotherapy in addition to MR imaging are successfully developed. A classical layer-by-layer technique of oppositely charged polyelectrolytes (poly(allylamine hydrochloride) (PAH) and poly(4-styrene sulfonate sodium) (PSS)) is used as it affords great controllability over the preparation together with enhanced loading of the chemotherapeutic drug (doxorubicin, DOX) in the microcapsules. Superparamagnetic iron oxide (SPIOs) nanoparticles are layered in the system to afford MMC1 (one SPIOs layer) and MMC2 (two SPIOs layers). Most interestingly, MMC1 and MMC2 show efficient hyperthermia cell death and controlled DOX release although their magnetic saturation value falls below 2.5 emu g-1, which is lower than the 7-22 emu g-1 reported to be the minimum value needed for biomedical applications. Moreover, MMCs are pH responsive where a pH 5.5 (often reported for cancer cells) combined with hyperthermia increases DOX release predictably. Both systems prove viable when used as T2 contrast agents for MR imaging in HeLa cells with high biocompatibility. Thus, MMCs hold a great promise to be used commercially as a theranostic platform as they are controllably prepared, reproducibly enhanced, and serve as drug delivery, hyperthermia, and MRI contrast agents at the same time.

Nanohybrids with Magnetic and Persistent Luminescence Properties for Cell Labeling, Tracking, In Vivo Real-Time Imaging, and Magnetic Vectorization.

Science.gov (United States)

Teston, Eliott; Maldiney, Thomas; Marangon, Iris; Volatron, Jeanne; Lalatonne, Yoann; Motte, Laurence; Boisson-Vidal, Catherine; Autret, Gwennhael; Clément, Olivier; Scherman, Daniel; Gazeau, Florence; Richard, Cyrille

2018-04-01

Once injected into a living organism, cells diffuse or migrate around the initial injection point and become impossible to be visualized and tracked in vivo. The present work concerns the development of a new technique for therapeutic cell labeling and subsequent in vivo visualization and magnetic retention. It is hypothesized and subsequently demonstrated that nanohybrids made of persistent luminescence nanoparticles and ultrasmall superparamagnetic iron oxide nanoparticles incorporated into a silica matrix can be used as an effective nanoplatform to label therapeutic cells in a nontoxic way in order to dynamically track them in real-time in vitro and in living mice. As a proof-of-concept, it is shown that once injected, these labeled cells can be visualized and attracted in vivo using a magnet. This first step suggests that these nanohybrids represent efficient multifunctional nanoprobes for further imaging guided cell therapies development. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A magnetic micropore chip for rapid (<1 hour) unbiased circulating tumor cell isolation and in situ RNA analysis.

Science.gov (United States)

Ko, Jina; Bhagwat, Neha; Yee, Stephanie S; Black, Taylor; Redlinger, Colleen; Romeo, Janae; O'Hara, Mark; Raj, Arjun; Carpenter, Erica L; Stanger, Ben Z; Issadore, David

2017-09-12

The use of microtechnology for the highly selective isolation and sensitive detection of circulating tumor cells has shown enormous promise. One challenge for this technology is that the small feature sizes - which are the key to this technology's performance - can result in low sample throughput and susceptibility to clogging. Additionally, conventional molecular analysis of CTCs often requires cells to be taken off-chip for sample preparation and purification before analysis, leading to the loss of rare cells. To address these challenges, we have developed a microchip platform that combines fast, magnetic micropore based negative immunomagnetic selection (>10 mL h -1 ) with rapid on-chip in situ RNA profiling (>100× faster than conventional RNA labeling). This integrated chip can isolate both rare circulating cells and cell clusters directly from whole blood and allow individual cells to be profiled for multiple RNA cancer biomarkers, achieving sample-to-answer in less than 1 hour for 10 mL of whole blood. To demonstrate the power of this approach, we applied our device to the circulating tumor cell based diagnosis of pancreatic cancer. We used a genetically engineered lineage-labeled mouse model of pancreatic cancer (KPCY) to validate the performance of our chip. We show that in a cohort of patient samples (N = 25) that this device can detect and perform in situ RNA analysis on circulating tumor cells in patients with pancreatic cancer, even in those with extremely sparse CTCs (<1 CTC mL -1 of whole blood).

The effect of cryoprotection on the use of PLGA encapsulated iron oxide nanoparticles for magnetic cell labeling

International Nuclear Information System (INIS)

Tang, Kevin S; Shapiro, Erik M; Hashmi, Sarah M

2013-01-01

Magnetic PLGA nanoparticles are a significant advancement in the quest to translate MRI-based cell tracking to the clinic. The benefits of these types of particles are that they encapsulate large amounts of iron oxide nanocrystals within an FDA-approved polymer matrix, combining the best aspects of inert micron-sized iron oxide particles, or MPIOs, and biodegradable small particles of iron oxide, or SPIOs. Practically, PLGA nanoparticle fabrication and storage requires some form of cryoprotectant to both protect the particle during freeze drying and to promote resuspension. While this is a commonly employed procedure in the fabrication of drug loaded PLGA nanoparticles, it has yet to be investigated for magnetic particles and what effect this might have on internalization of magnetic particles. As such, in this study, magnetic PLGA nanoparticles were fabricated with various concentrations of two common cryoprotectants, dextrose and sucrose, and analyzed for their ability to magnetically label cells. It was found that cryoprotection with either sugar significantly enhanced the ability to resuspend nanoparticles without aggregation. Magnetic cell labeling was impacted by sugar concentration, with higher sugar concentrations used during freeze drying more significantly reducing magnetic cell labeling than lower concentrations. These studies suggest that cryoprotection with 1% dextrose is an optimal compromise that preserves monodispersity following resuspension and high magnetic cell labeling. (paper)

Hypericin-bearing magnetic iron oxide nanoparticles for selective drug delivery in photodynamic therapy

Directory of Open Access Journals (Sweden)

Unterweger H

2015-11-01

Full Text Available Harald Unterweger,1 Daniel Subatzus,1 Rainer Tietze,1 Christina Janko,1 Marina Poettler,1 Alfons Stiegelschmitt,2 Matthias Schuster,3 Caroline Maake,4 Aldo R Boccaccini,5 Christoph Alexiou11ENT Department, Section of Experimental Oncology and Nanomedicine (SEON, Else Kröner-Fresenius-Stiftung Professorship, University Hospital Erlangen; 2Institute of Glass and Ceramics, Department of Materials Science and Engineering, University Erlangen-Nuremberg, 3Materials for Electronics and Energy Technology, Department of Materials Science and Engineering, University Erlangen-Nürnberg, Erlangen, Germany; 4Institute of Anatomy, University of Zurich, Winterthurerstr, Zurich, Switzerland; 5Institute of Biomaterials, Department of Materials Science and Engineering, University Erlangen-Nuremberg, Erlangen, Germany Abstract: Combining the concept of magnetic drug targeting and photodynamic therapy is a promising approach for the treatment of cancer. A high selectivity as well as significant fewer side effects can be achieved by this method, since the therapeutic treatment only takes place in the area where accumulation of the particles by an external electromagnet and radiation by a laser system overlap. In this article, a novel hypericin-bearing drug delivery system has been developed by synthesis of superparamagnetic iron oxide nanoparticles (SPIONs with a hypericin-linked functionalized dextran coating. For that, sterically stabilized dextran-coated SPIONs were produced by coprecipitation and crosslinking with epichlorohydrin to enhance stability. Carboxymethylation of the dextran shell provided a functionalized platform for linking hypericin via glutaraldehyde. Particle sizes obtained by dynamic light scattering were in a range of 55–85 nm, whereas investigation of single magnetite or maghemite particle diameter was performed by transmission electron microscopy and X-ray diffraction and resulted in approximately 4.5–5.0 nm. Surface chemistry of those

4β-Hydroxywithanolide E selectively induces oxidative DNA damage for selective killing of oral cancer cells.

Science.gov (United States)

Tang, Jen-Yang; Huang, Hurng-Wern; Wang, Hui-Ru; Chan, Ya-Ching; Haung, Jo-Wen; Shu, Chih-Wen; Wu, Yang-Chang; Chang, Hsueh-Wei

2018-03-01

Reactive oxygen species (ROS) induction had been previously reported in 4β-hydroxywithanolide (4βHWE)-induced selective killing of oral cancer cells, but the mechanism involving ROS and the DNA damage effect remain unclear. This study explores the role of ROS and oxidative DNA damage of 4βHWE in the selective killing of oral cancer cells. Changes in cell viability, morphology, ROS, DNA double strand break (DSB) signaling (γH2AX foci in immunofluorescence and DSB signaling in western blotting), and oxidative DNA damage (8-oxo-2'deoxyguanosine [8-oxodG]) were detected in 4βHWE-treated oral cancer (Ca9-22) and/or normal (HGF-1) cells. 4βHWE decreased cell viability, changed cell morphology and induced ROS generation in oral cancer cells rather than oral normal cells, which were recovered by a free radical scavenger N-acetylcysteine (NAC). For immunofluorescence, 4βHWE also accumulated more of the DSB marker, γH2AX foci, in oral cancer cells than in oral normal cells. For western blotting, DSB signaling proteins such as γH2AX and MRN complex (MRE11, RAD50, and NBS1) were overexpressed in 4βHWE-treated oral cancer cells in different concentrations and treatment time. In the formamidopyrimidine-DNA glycolyase (Fpg)-based comet assay and 8-oxodG-based flow cytometry, the 8-oxodG expressions were higher in 4βHWE-treated oral cancer cells than in oral normal cells. All the 4βHWE-induced DSB and oxidative DNA damage to oral cancer cells were recovered by NAC pretreatment. Taken together, the 4βHWE selectively induced DSB and oxidative DNA damage for the ROS-mediated selective killing of oral cancer cells. © 2017 Wiley Periodicals, Inc.

Selection of the optimum magnet design for the International Linear Collider positron source helical undulator

Directory of Open Access Journals (Sweden)

D. J. Scott

2007-03-01

Full Text Available A comparison of possible undulator designs for the International Linear Collider positron source has resulted in a superconducting bifilar wire design being selected. After a comprehensive paper study and fabrication of the two preeminent designs, the superconducting undulator was chosen instead of the permanent magnet alternative. This was because of its superior performance in terms of magnetic field strength and quality, operational flexibility, risk of radiation damage, ease in achieving the required vacuum, and cost. The superconducting undulator design will now be developed into a complete system design for the full 200 m long magnet that is required.

Tracking stem cells in tissue-engineered organs using magnetic nanoparticles

OpenAIRE

Hachani, R.; Lowdell, M.; Birchall, M.; Thanh, N. T.

2013-01-01

The use of human stem cells (SCs) in tissue engineering holds promise in revolutionising the treatment of numerous diseases. There is a pressing need to comprehend the distribution, movement and role of SCs once implanted onto scaffolds. Nanotechnology has provided a platform to investigate this through the development of inorganic magnetic nanoparticles (MNPs). MNPs can be used to label and track SCs by magnetic resonance imaging (MRI) since this clinically available imaging modality has hig...

Magnetic molecularly imprinted polymer for the selective extraction of hesperetin from the dried pericarp of Citrus reticulata Blanco.

Science.gov (United States)

Wang, Dan-Dan; Gao, Die; Xu, Wan-Jun; Li, Fan; Yin, Man-Ni; Fu, Qi-Feng; Xia, Zhi-Ning

2018-07-01

In present study, novel magnetic molecularly imprinted polymers for hesperetin were successfully prepared by surface molecular imprinting method using functionalized Fe 3 O 4 particles as the magnetic cores. Hesperetin as the template, N-Isopropylacrylamide as the functional monomer, ethylene glycol dimethyl acrylate as the crosslinker, 2,2-azobisisobutyonnitrile as initiator and acetonitrile-methanol (3:1, v/v) as the porogen were applied in the preparation process. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscope, x-ray diffraction and vibrating sample magnetometry were applied to characterize the magnetic molecularly imprinted polymers. The adsorption experiments indicated that the magnetic molecularly imprinted polymers performed high selective recognition property to hesperetin. The selectivity experiment indicated that the adsorption capacity and selectivity of polymers to hesperetin was higher than that of luteolin, baicalein and ombuin. Furthermore, the magnetic molecularly imprinted polymers were employed as adsorbents for extraction and enrichment of hesperetin from the dried pericarp of Citrus reticulata Blanco. The recoveries of hesperetin in the dried pericarp of Citrus reticulata Blanco ranged from 90.5% to 96.9%. The linear range of 0.15-110.72 µg/mL was obtained with correlation coefficient of greater than 0.9991. The limit of detection and quantification of the proposed method was 0.06 µg/mL and 0.15 µg/mL, respectively. Based on three replicate measurements, intra-day RSD was 0.71% and inter-day RSD was 2.31%. These results demonstrated that the prepared magnetic molecularly imprinted polymers were proven to be an effective material for the selective adsorption and enrichment of hesperetin from natural medicines, fruits and et al. Copyright © 2018 Elsevier B.V. All rights reserved.

The effect of two novel amino acid-coated magnetic nanoparticles on survival in vascular endothelial cells, bone marrow stromal cells, and macrophages

Science.gov (United States)

Wu, Qinghua; Meng, Ning; Zhang, Yanru; Han, Lei; Su, Le; Zhao, Jing; Zhang, Shangli; Zhang, Yun; Zhao, Baoxiang; Miao, Junying

2014-09-01

Magnetic nanoparticles (MNPs) have been popularly used in many fields. Recently, many kinds of MNPs are modified as new absorbents, which have attracted considerable attention and are promising to be applied in waste water. In our previous study, we synthesized two novel MNPs surface-coated with glycine or lysine, which could efficiently remove many anionic and cationic dyes under severe conditions. It should be considered that MNP residues in water may exert some side effects on human health. In the present study, we evaluated the potential nanotoxicity of MNPs in human endothelial cells, macrophages, and rat bone marrow stromal cells. The results showed that the two kinds of nanoparticles were consistently absorbed into the cell cytoplasm. The concentration of MNPs@Gly that could distinctly decrease survival was 15 μg/ml in human umbilical vascular endothelial cells (HUVECs) or bone marrow stromal cells (BMSCs) and 10 μg/ml in macrophages. While the concentration of MNPs@Lys that obviously reduced viability was 15 μg/ml in HUVECs or macrophages and 50 μg/ml in BMSCs. Furthermore, cell nucleus staining and cell integrity assay indicated that the nanoparticles induced cell apoptosis, but not necrosis even at a high concentration. Altogether, these data suggest that the amino acid-coated magnetic nanoparticles exert relatively high cytotoxicity. By contrast, lysine-coated magnetic nanoparticles are more secure than glycine-coated magnetic nanoparticles.

Magnetic Enrichment of Dendritic Cell Vaccine in Lymph Node with Fluorescent-Magnetic Nanoparticles Enhanced Cancer Immunotherapy

Science.gov (United States)

Jin, Honglin; Qian, Yuan; Dai, Yanfeng; Qiao, Sha; Huang, Chuan; Lu, Lisen; Luo, Qingming; Chen, Jing; Zhang, Zhihong

2016-01-01

Dendritic cell (DC) migration to the lymph node is a key component of DC-based immunotherapy. However, the DC homing rate to the lymphoid tissues is poor, thus hindering the DC-mediated activation of antigen-specific T cells. Here, we developed a system using fluorescent magnetic nanoparticles (α-AP-fmNPs; loaded with antigen peptide, iron oxide nanoparticles, and indocyanine green) in combination with magnetic pull force (MPF) to successfully manipulate DC migration in vitro and in vivo. α-AP-fmNPs endowed DCs with MPF-responsiveness, antigen presentation, and simultaneous optical and magnetic resonance imaging detectability. We showed for the first time that α-AP-fmNP-loaded DCs were sensitive to MPF, and their migration efficiency could be dramatically improved both in vitro and in vivo through MPF treatment. Due to the enhanced migration of DCs, MPF treatment significantly augmented antitumor efficacy of the nanoparticle-loaded DCs. Therefore, we have developed a biocompatible approach with which to improve the homing efficiency of DCs and subsequent anti-tumor efficacy, and track their migration by multi-modality imaging, with great potential applications for DC-based cancer immunotherapy. PMID:27698936

Magnetic engineering of stable rod-shaped stem cell aggregates: circumventing the pitfall of self-bending.

Science.gov (United States)

Du, V; Fayol, D; Reffay, M; Luciani, N; Bacri, J-C; Gay, C; Wilhelm, C

2015-02-01

A current challenge for tissue engineering while restoring the function of diseased or damaged tissue is to customize the tissue according to the target area. Scaffold-free approaches usually yield spheroid shapes with the risk of necrosis at the center due to poor nutrient and oxygen diffusion. Here, we used magnetic forces developed at the cellular scale by miniaturized magnets to create rod-shaped aggregates of stem cells that subsequently matured into a tissue-like structure. However, during the maturation process, the tissue-rods spontaneously bent and coiled into sphere-like structures, triggered by the increasing cell-cell adhesion within the initially non-homogeneous tissue. Optimisation of the intra-tissular magnetic forces successfully hindered the transition, in order to produce stable rod-shaped stem cells aggregates.

Evaluation of biological effects of intermediate frequency magnetic field on differentiation of embryonic stem cell.

Science.gov (United States)

Yoshie, Sachiko; Ogasawara, Yuki; Ikehata, Masateru; Ishii, Kazuyuki; Suzuki, Yukihisa; Wada, Keiji; Wake, Kanako; Nakasono, Satoshi; Taki, Masao; Ohkubo, Chiyoji

2016-01-01

The embryotoxic effect of intermediate frequency (IF) magnetic field (MF) was evaluated using murine embryonic stem (ES) cells and fibroblast cells based on the embryonic stem cell test (EST). The cells were exposed to 21 kHz IF-MF up to magnetic flux density of 3.9 mT during the cell proliferation process (7 days) or the cell differentiation process (10 days) during which an embryonic body differentiated into myocardial cells. As a result, there was no significant difference in the cell proliferation between sham- and IF-MF-exposed cells for both ES and fibroblast cells. Similarly, the ratio of the number of ES-derived cell aggregates differentiated to myocardial cells to total number of cell aggregates was not changed by IF-MF exposure. In addition, the expressions of a cardiomyocytes-specific gene, Myl2 , and an early developmental gene, Hba-x , in the exposed cell aggregate were not altered. Since the magnetic flux density adopted in this study is much higher than that generated by an inverter of the electrical railway, an induction heating (IH) cooktop, etc . in our daily lives, these results suggested that IF-MF in which the public is exposed to in general living environment would not have embryotoxic effect.

Antibody-directed lentiviral gene transduction for live-cell monitoring and selection of human iPS and hES cells.

Directory of Open Access Journals (Sweden)

Dai-tze Wu

Full Text Available The identification of stem cells within a mixed population of cells is a major hurdle for stem cell biology--in particular, in the identification of induced pluripotent stem (iPS cells during the reprogramming process. Based on the selective expression of stem cell surface markers, a method to specifically infect stem cells through antibody-conjugated lentiviral particles has been developed that can deliver both visual markers for live-cell imaging as well as selectable markers to enrich for iPS cells. Antibodies recognizing SSEA4 and CD24 mediated the selective infection of the iPS cells over the parental human fibroblasts, allowing for rapid expansion of these cells by puromycin selection. Adaptation of the vector allows for the selective marking of human embryonic stem (hES cells for their removal from a population of differentiated cells. This method has the benefit that it not only identifies stem cells, but that specific genes, including positive and negative selection markers, regulatory genes or miRNA can be delivered to the targeted stem cells. The ability to specifically target gene delivery to human pluripotent stem cells has broad applications in tissue engineering and stem cell therapies.

A novel magnetic ion imprinted polymer as a selective magnetic solid phase for separation of trace lead(II) ions from agricultural products, and optimization using a Box-Behnken design.

Science.gov (United States)

Dahaghin, Zohreh; Mousavi, Hassan Zavvar; Sajjadi, S Maryam

2017-12-15

In this work, a magnetic ion-imprinted polymer (Fe 3 O 4 @SiO 2 @IIP) as a novel and selective nanosorbent for selective extraction of Pb(II) ions from various agricultural products is presented. The novel lead magnetic ion-imprinted polymer was synthesized by imidazole as a new ligand and grafted onto the surface of Fe 3 O 4 @SiO 2 NPs. A Box-Behnken (BBD) design was used for optimization of the extraction and elution steps. In the selected conditions, the limit of detection was 0.48ngmL -1 , preconcentration factor was 300, the sorption capacity of this new magnetic ion-imprinted polymer was 105mgg -1 , and the precision of the method (RSD%) for six replicate measurements was found 3.2%. Finally, the feasibility of the new magnetic ion-imprinted polymer was evaluated by extraction and determination of trace Pb 2+ ions in different agricultural products including (orange, mango, apple, kiwi, lettuce, broccoli, carrot, squash, eggplant, radish, mushroom, cucumber, and tomato). Copyright © 2017 Elsevier Ltd. All rights reserved.

High-capacity thermo-responsive magnetic molecularly imprinted polymers for selective extraction of curcuminoids.

Science.gov (United States)

You, Qingping; Zhang, Yuping; Zhang, Qingwen; Guo, Junfang; Huang, Weihua; Shi, Shuyun; Chen, Xiaoqin

2014-08-08

Thermo-responsive magnetic molecularly imprinted polymers (TMMIPs) for selective recognition of curcuminoids with high capacity and selectivity have firstly been developed. The resulting TMMIPs were characterized by TEM, FT-IR, TGA, VSM and UV, which indicated that TMMIPs showed thermo-responsiveness [lower critical solution temperature (LCST) at 33.71°C] and rapid magnetic separation (5s). The polymerization, adsorption and release conditions were optimized in detail to obtain the highest binding capacity, selectivity and release ratio. We found that the adopted thermo-responsive monomer [N-isopropylacrylamide (NIPAm)] could be considered not only as inert polymer backbone for thermo-responsiveness but also as functional co-monomers combination with basic monomer (4-VP) for more specific binding sites when ethanol was added in binding solution. The maximum adsorption capacity with highest selectivity of curcumin was 440.3μg/g (1.93 times that on MMIPs with no thermosensitivity) at 45°C (above LCST) in 20% (v/v) ethanol solution on shrunk TMMIPs, and the maximum release proportion was about 98% at 20°C (below LCST) in methanol-acetic acid (9/1, v/v) solution on swelled TMMIPs. The adsorption process between curcumin and TMMIPs followed Langumuir adsorption isotherm and pseudo-first-order reaction kinetics. The prepared TMMIPs also showed high reproducibility (RSD<6% for batch-to-batch evaluation) and stability (only 7% decrease after five cycles). Subsequently, the TMMIPs were successfully applied for selective extraction of curcuminoids from complex natural product, Curcuma longa. Copyright © 2014 Elsevier B.V. All rights reserved.

Aptamer-based isolation and subsequent imaging of mesenchymal stem cells in ischemic myocard by magnetic resonance imaging.

Science.gov (United States)

Schäfer, R; Wiskirchen, J; Guo, K; Neumann, B; Kehlbach, R; Pintaske, J; Voth, V; Walker, T; Scheule, A M; Greiner, T O; Hermanutz-Klein, U; Claussen, C D; Northoff, H; Ziemer, G; Wendel, H P

2007-10-01

Mesenchymal stem cells (MSC) seem to be a promising cell source for cellular cardiomyoplasty. We recently developed a new aptamer-based specific selection of MSC to provide "ready to transplant" cells directly after isolation. We evaluated MRI tracking of newly isolated and freshly transplanted MSC in the heart using one short ex vivo selection step combining specific aptamer-based isolation and labeling of the cells. Bone marrow (BM) was collected from healthy pigs. The animals were euthanized and the heart was placed in a perfusion model. During cold ischemia, immunomagnetic isolation of MSC from the BM by MSC-specific aptamers labeled with Dynabeads was performed within 2 h. For histological identification the cells were additionally stained with PKH26. Approx. 3 x 10(6) of the freshly aptamer-isolated cells were injected into the ramus interventricularis anterior (RIVA) and 5 x 10(5) cells were injected directly into myocardial tissue after damaging the respective area by freezing (cryo-scar). 3 x 10(6) of the aptamer-isolated cells were kept for further characterization (FACS and differentiation assays). 20 h after cell transplantation, MRI of the heart using a clinical 3.0 Tesla whole body scanner (Magnetom Trio, Siemens, Germany) was performed followed by histological examinations. The average yield of sorted cells from 120 ml BM was 7 x 10(6) cells. The cells were cultured and showed MSC-like properties. MRI showed reproducible artifacts within the RIVA-perfusion area and the cryo-scar with surprisingly excellent quality. The histological examination of the biopsies showed PKH26-positive cells within the areas which were positive in the MRI in contrast to the control biopsies. Immunomagnetic separation of MSC by specific aptamers linked to magnetic particles is feasible, effective and combines a specific separation and labeling technique to a "one stop shop" strategy.

Microfluidic synthesis of microfibers for magnetic-responsive controlled drug release and cell culture.

Directory of Open Access Journals (Sweden)

Yung-Sheng Lin

Full Text Available This study demonstrated the fabrication of alginate microfibers using a modular microfluidic system for magnetic-responsive controlled drug release and cell culture. A novel two-dimensional fluid-focusing technique with multi-inlets and junctions was used to spatiotemporally control the continuous laminar flow of alginate solutions. The diameter of the manufactured microfibers, which ranged from 211 µm to 364 µm, could be well controlled by changing the flow rate of the continuous phase. While the model drug, diclofenac, was encapsulated into microfibers, the drug release profile exhibited the characteristic of a proper and steady release. Furthermore, the diclofenac release kinetics from the magnetic iron oxide-loaded microfibers could be controlled externally, allowing for a rapid drug release by applying a magnetic force. In addition, the successful culture of glioblastoma multiforme cells in the microfibers demonstrated a good structural integrity and environment to grow cells that could be applied in drug screening for targeting cancer cells. The proposed microfluidic system has the advantages of ease of fabrication, simplicity, and a fast and low-cost process that is capable of generating functional microfibers with the potential for biomedical applications, such as drug controlled release and cell culture.

Increasing the sensitivity for stem cell monitoring in system-function based magnetic particle imaging

International Nuclear Information System (INIS)

Them, Kolja; Szwargulski, P; Knopp, Tobias; Salamon, J; Kaul, M G; Ittrich, H; Sequeira, S; Lange, C

2016-01-01

The use of superparamagnetic iron oxide nanoparticles (SPIONs) has provided new possibilities in biophysics and biomedical imaging technologies. The magnetization dynamics of SPIONs, which can be influenced by the environment, are of central interest. In this work, different biological SPION environments are used to investigate three different calibration methods for stem cell monitoring in magnetic particle imaging. It is shown that calibrating using SPIONs immobilized via agarose gel or intracellular uptake results in superior stem cell image quality compared to mobile SPIONs in saline. This superior image quality enables more sensitive localization and identification of a significantly smaller number of magnetically labeled stem cells. The results are important for cell tracking and monitoring of future SPION based therapies such as hyperthermia based cancer therapies, targeted drug delivery, or tissue regeneration approaches where it is crucial to image a sufficiently small number of SPIONs interacting with biological matter. (paper)

Magnetic poly(lactide-co-glycolide) (PLGA) and cellulose particles for MRI-based cell tracking

Science.gov (United States)

Nkansah, Michael K.; Thakral, Durga; Shapiro, Erik M.

2010-01-01

Biodegradable, superparamagnetic micro- and nanoparticles of poly(lactide-co-glycolide) (PLGA) and cellulose were designed, fabricated and characterized for magnetic cell labeling. Monodisperse nanocrystals of magnetite were incorporated into micro- and nanoparticles of PLGA and cellulose with high efficiency using an oil-in-water single emulsion technique. Superparamagnetic cores had high magnetization (72.1 emu/g). The resulting polymeric particles had smooth surface morphology and high magnetite content (43.3 wt% for PLGA and 69.6 wt% for cellulose). While PLGA and cellulose nanoparticles displayed highest r2* values per millimole of iron (399 s-1mM-1 for cellulose and 505 s-1mM-1 for PLGA), micron-sized PLGA particles had a much higher r2* per particle than either. After incubation for a month in citrate buffer (pH 5.5), magnetic PLGA particles lost close to 50% of their initial r2* molar relaxivity, while magnetic cellulose particles remained intact, preserving over 85% of their initial r2* molar relaxivity. Lastly, mesenchymal stem cells and human breast adenocarcinoma cells were magnetically labeled using these particles with no detectable cytotoxicity. These particles are ideally suited for non-invasive cell tracking in vivo via MRI and due to their vastly different degradation properties, offer unique potential for dedicated use for either short (PLGA-based particles) or long term (cellulose-based particles) experiments. PMID:21404328

GEM-loaded magnetic albumin nanospheres modified with cetuximab for simultaneous targeting, magnetic resonance imaging, and double-targeted thermochemotherapy of pancreatic cancer cells.

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Wang, Ling; An, Yanli; Yuan, Chenyan; Zhang, Hao; Liang, Chen; Ding, Fengan; Gao, Qi; Zhang, Dongsheng

2015-01-01

Targeted delivery is a promising strategy to improve the diagnostic imaging and therapeutic effect of cancers. In this paper, novel cetuximab (C225)-conjugated, gemcitabine (GEM)-containing magnetic albumin nanospheres (C225-GEM/MANs) were fabricated and applied as a theranostic nanocarrier to conduct simultaneous targeting, magnetic resonance imaging (MRI), and double-targeted thermochemotherapy against pancreatic cancer cells. Fe3O4 nanoparticles (NPs) and GEM co-loaded albumin nanospheres (GEM/MANs) were prepared, and then C225 was further conjugated to synthesize C225-GEM/MANs. Their morphology, mean particle size, GEM encapsulation ratio, specific cell-binding ability, and thermal dynamic profiles were characterized. The effects of discriminating different EGFR-expressing pancreatic cancer cells (AsPC-1 and MIA PaCa-2) and monitoring cellular targeting effects were assessed by targeted MRI. Lastly, the antitumor efficiency of double/C225/magnetic-targeted and nontargeted thermochemotherapy was compared with chemotherapy alone using 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and flow cytometry (FCM) assay. When treated with targeted nanospheres, AsPC-1 cells showed a significantly less intense MRI T2 signal than MIA PaCa-2 cells, while both cells had similar signal strength when incubated with nontargeted nanospheres. T2 signal intensity was significantly lower when magnetic and C225 targeting were combined, rather than used alone. The inhibitory and apoptotic rates of each thermochemotherapy group were significantly higher than those of the chemotherapy-alone groups. Additionally, both MTT and FCM analysis verified that double-targeted thermochemotherapy had the highest targeted killing efficiency among all groups. The C225-GEM/MANs can distinguish various EGFR-expressing live pancreatic cancer cells, monitor diverse cellular targeting effects using targeted MRI imaging, and efficiently mediate double-targeted thermochemotherapy

Cell-Selective Biological Activity of Rhodium Metalloinsertors Correlates with Subcellular Localization

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Komor, Alexis C.; Schneider, Curtis J.; Weidmann, Alyson G.; Barton, Jacqueline K.

2013-01-01

Deficiencies in the mismatch repair (MMR) pathway are associated with several types of cancers, as well as resistance to commonly used chemotherapeutics. Rhodium metalloinsertors have been found to bind DNA mismatches with high affinity and specificity in vitro, and also exhibit cell-selective cytotoxicity, targeting MMR-deficient cells over MMR-proficient cells. Ten distinct metalloinsertors with varying lipophilicities have been synthesized and their mismatch binding affinities and biological activities determined. Although DNA photocleavage experiments demonstrate that their binding affinities are quite similar, their cell-selective antiproliferative and cytotoxic activities vary significantly. Inductively coupled plasma mass spectrometry (ICP-MS) experiments have uncovered a relationship between the subcellular distribution of these metalloinsertors and their biological activities. Specifically, we find that all of our metalloinsertors localize in the nucleus at sufficient concentrations for binding to DNA mismatches. However, the metalloinsertors with high rhodium localization in the mitochondria show toxicity that is not selective for MMR-deficient cells, whereas metalloinsertors with less mitochondrial rhodium show activity that is highly selective for MMR-deficient versus proficient cells. This work supports the notion that specific targeting of the metalloinsertors to nuclear DNA gives rise to their cell-selective cytotoxic and antiproliferative activities. The selectivity in cellular targeting depends upon binding to mismatches in genomic DNA. PMID:23137296

Synthesis and Characterization of Magnetic-Graphene Molecularly Imprinted Polymers for Selective Recognition of Ltryptophan

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Zhang Yi

2017-01-01

Full Text Available In this paper, a novel molecular imprinted polymer using L-tryptophan(L-Trp as the template, dopamine(DA as both functional monomer and cross linking agent, magnetic graphene as the supporting matrix was synthesized. The prepared magnetic-graphene molecularly imprinted polymers(Fe3O4@GO-MIPs were characterized by Fourier transform infrared spectrometer(FT-IR, transmission electron microscopy (TEM, vibrating sample magnetometer (VSM, respectively. The results showed that when the molar ratio of L- tryptophan and dopamine was 1:4 and the reaction temperature was 60 °C, Fe3O4@GO-MIPs had the best adsorption quantity of 31.9 mg/g. The rebinding experiments indicated that Fe3O4@GO-MIPs not only have outstanding affinity and selectivity towards L-Trp over structurally related compounds but also easily reach the magnetic separation under an external magnetic field.

Dyes adsorption on magnetically modified Chlorella vulgaris cells

Czech Academy of Sciences Publication Activity Database

Šafaříková, Miroslava; Pona, B. M. R.; Mosiniewicz-Szablewska, E.; Weyda, František; Šafařík, Ivo

2008-01-01

Roč. 17, č. 4 (2008), s. 486-492 ISSN 1018-4619 R&D Projects: GA MŠk OC 108; GA MPO 2A-1TP1/094 Institutional research plan: CEZ:AV0Z60870520; CEZ:AV0Z50070508 Keywords : Chlorella vulgaris * magnetically modified cells * dyes Subject RIV: EI - Biotechnology ; Bionics Impact factor: 0.463, year: 2008

Using injection molding and reversible bonding for easy fabrication of magnetic cell trapping and sorting devices

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Royet, David; Hériveaux, Yoann; Marchalot, Julien; Scorretti, Riccardo; Dias, André; Dempsey, Nora M.; Bonfim, Marlio; Simonet, Pascal; Frénéa-Robin, Marie

2017-04-01

Magnetism and microfluidics are two key elements for the development of inexpensive and reliable tools dedicated to high-throughput biological analysis and providing a large panel of applications in domains ranging from fundamental biology to medical diagnostics. In this work, we introduce a simple protocol, relying on injection molding and reversible bonding for fabrication of magnetic cell trapping and sorting devices using only standard soft-lithography equipment. Magnetic strips or grids made of Polydimethylsiloxane (PDMS) doped with hard (NdFeB) or soft (carbonyl iron) magnetic powders were integrated at the bottom of whole PDMS chips. Preliminary results show the effective deviation/trapping of magnetic beads or magnetically-labeled bacteria as the sample flows through the microchannel, proving the potential of this rapid prototyping approach for easy fabrication of magnetic cell sorters.

The Effect of 217 Hz Magnetic Field of Cell Phone with Different Intensities on Apoptosis of Normal and Cancerous Cells Treated with Chemotherapy Drug

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Mahsa Mansourian

2012-03-01

Full Text Available Background: According to the increasing development of home and business electronic equipment in today's world, the biological effects of ELF magnetic fields have been studied at two molecular-cellular and animal- human levels. Considering the therapeutic viewpoint of this study regarding the effects of low-frequency fields of mobile phone, the effect of acute exposure to this field on chemotherapy will be studied.Materials and Methods: In this experimental study, based on measurement of the intensity of the magnetic fields from mobile phones in another research, flux densities of magnetic field of 159.44, 93.25 and 120µ tesla with frequency of 217Hz was generated in magnetic field generator system, and the apoptosis level in K562 cancer cells and healthy cells of lymphocytes was assessed after exposure to field using flow cytometry method. This evaluation method was also performed for the cells treated with bleomycin after exposure to this field.Results: 217 Hz magnetic field exposure significantly increases the rate of apoptosis percentage (p > 0.05 in K562 cancer cells and in two intensities of 120 and 159.44µ tesla compared to the control group, but such effect is not observed in lymphocyte cells. Bleomycin-induced apoptosis percentage following exposure to the mentioned magnetic field shows no significant difference compared to the group of treatment with drug and without field exposure. This lack of significant difference is observed between the groups of drug after field exposure and field alone as well as between groups exposed to field and groups treated with bleomycin.Conclusion: Study results showed that 217 Hz magnetic field of mobile phone can induce apoptosis on cancer cells, but it has no effect on healthy cells. Thus, in order to use mobile phone as an effective factor in their treatment, some studies should be conducted at animal-human level.

Possible promotion of neuronal differentiation in fetal rat brain neural progenitor cells after sustained exposure to static magnetism.

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Nakamichi, Noritaka; Ishioka, Yukichi; Hirai, Takao; Ozawa, Shusuke; Tachibana, Masaki; Nakamura, Nobuhiro; Takarada, Takeshi; Yoneda, Yukio

2009-08-15

We have previously shown significant potentiation of Ca(2+) influx mediated by N-methyl-D-aspartate receptors, along with decreased microtubules-associated protein-2 (MAP2) expression, in hippocampal neurons cultured under static magnetism without cell death. In this study, we investigated the effects of static magnetism on the functionality of neural progenitor cells endowed to proliferate for self-replication and differentiate into neuronal, astroglial, and oligodendroglial lineages. Neural progenitor cells were isolated from embryonic rat neocortex and hippocampus, followed by culture under static magnetism at 100 mT and subsequent determination of the number of cells immunoreactive for a marker protein of particular progeny lineages. Static magnetism not only significantly decreased proliferation of neural progenitor cells without affecting cell viability, but also promoted differentiation into cells immunoreactive for MAP2 with a concomitant decrease in that for an astroglial marker, irrespective of the presence of differentiation inducers. In neural progenitors cultured under static magnetism, a significant increase was seen in mRNA expression of several activator-type proneural genes, such as Mash1, Math1, and Math3, together with decreased mRNA expression of the repressor type Hes5. These results suggest that sustained static magnetism could suppress proliferation for self-renewal and facilitate differentiation into neurons through promoted expression of activator-type proneural genes by progenitor cells in fetal rat brain.

Group 3 innate lymphoid cells mediate intestinal selection of commensal bacteria-specific CD4+ T cells

Science.gov (United States)

Hepworth, Matthew R.; Fung, Thomas C.; Masur, Samuel H.; Kelsen, Judith R.; McConnell, Fiona M.; Dubrot, Juan; Withers, David R.; Hugues, Stephanie; Farrar, Michael A.; Reith, Walter; Eberl, Gerard; Baldassano, Robert N.; Laufer, Terri M.; Elson, Charles O.; Sonnenberg, Gregory F.

2015-01-01

Inflammatory CD4+ T cell responses to self or commensal bacteria underlie the pathogenesis of autoimmunity and inflammatory bowel disease (IBD), respectively. While selection of self-specific T cells in the thymus limits responses to tissue antigens, the mechanisms that control selection of commensal bacteria-specific T cells remain poorly understood. Here we demonstrate that group 3 innate lymphoid cell (ILC3)-intrinsic expression of major histocompatibility complex class II (MHCII) is regulated similarly to thymic epithelial cells, and that MHCII+ ILC3s directly induce cell death of activated commensal bacteria-specific T cells. Further, MHCII on human colonic ILC3s was reduced in pediatric IBD patients. Collectively, these results define a selection pathway for commensal bacteria-specific CD4+ T cells in the intestine, and suggest that this process is dysregulated in human IBD. PMID:25908663

Increasing magnetite contents of polymeric magnetic particles dramatically improves labeling of neural stem cell transplant populations.

Science.gov (United States)

Adams, Christopher F; Rai, Ahmad; Sneddon, Gregor; Yiu, Humphrey H P; Polyak, Boris; Chari, Divya M

2015-01-01

Safe and efficient delivery of therapeutic cells to sites of injury/disease in the central nervous system is a key goal for the translation of clinical cell transplantation therapies. Recently, 'magnetic cell localization strategies' have emerged as a promising and safe approach for targeted delivery of magnetic particle (MP) labeled stem cells to pathology sites. For neuroregenerative applications, this approach is limited by the lack of available neurocompatible MPs, and low cell labeling achieved in neural stem/precursor populations. We demonstrate that high magnetite content, self-sedimenting polymeric MPs [unfunctionalized poly(lactic acid) coated, without a transfecting component] achieve efficient labeling (≥90%) of primary neural stem cells (NSCs)-a 'hard-to-label' transplant population of major clinical relevance. Our protocols showed high safety with respect to key stem cell regenerative parameters. Critically, labeled cells were effectively localized in an in vitro flow system by magnetic force highlighting the translational potential of the methods used. Copyright © 2015 Elsevier Inc. All rights reserved.

Rapid Column-Free Enrichment of Mononuclear Cells from Solid Tissues

Science.gov (United States)

Scoville, Steven D.; Keller, Karen A.; Cheng, Stephanie; Zhang, Michael; Zhang, Xiaoli; Caligiuri, Michael A.; Freud, Aharon G.

2015-01-01

We have developed a rapid negative selection method to enrich rare mononuclear cells from human tissues. Unwanted and antibody-tethered cells are selectively depleted during a Ficoll separation step, and there is no need for magnetic-based reagents and equipment. The new method is fast, customizable, inexpensive, remarkably efficient, and easy to perform, and per sample the overall cost is less than one-tenth the cost associated with a magnetic column-based method. PMID:26223896

Nanosized As2O3/Fe2O3 complexes combined with magnetic fluid hyperthermia selectively target liver cancer cells.

Science.gov (United States)

Wang, Zi-Yu; Song, Jian; Zhang, Dong-Sheng

2009-06-28

To study the methods of preparing the magnetic nano-microspheres of Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) complexes and their therapeutic effects with magnetic fluid hyperthermia (MFH). Nanospheres were prepared by chemical co-precipitation and their shape and diameter were observed. Hemolysis, micronucleus, cell viability, and LD(50) along with other in vivo tests were performed to evaluate the Fe(2)O(3) microsphere biocompatibility. The inhibition ratio of tumors after Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) injections combined with induced hyperthermia in xenograft human hepatocarcinoma was calculated. Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) particles were round with an average diameter of 20 nm and 100 nm as observed under transmission electron microscope. Upon exposure to an alternating magnetic field (AMF), the temperature of the suspension of magnetic particles increased to 41-51 degrees C, depending on different particle concentrations, and remained stable thereafter. Nanosized Fe(2)O(3) microspheres are a new kind of biomaterial without cytotoxic effects. The LD(50) of both Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) in mice was higher than 5 g/kg. One to four weeks after Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) complex injections into healthy pig livers, no significant differences were found in serum AST, ALT, BUN and Cr levels among the pigs of all groups (P > 0.05), and no obvious pathological alterations were observed. After exposure to alternating magnetic fields, the inhibition ratio of the tumors was significantly different from controls in the Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) groups (68.74% and 82.79%, respectively; P < 0.01). Tumors of mice in treatment groups showed obvious necrosis, while normal tissues adjoining the tumor and internal organs did not. Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) complexes exerted radiofrequency-induced hyperthermia and drug toxicity on tumors without any liver or kidney damage. Therefore, nanospheres are ideal carriers for tumor-targeted therapy.

Combinational Effect of Cell Adhesion Biomolecules and Their Immobilized Polymer Property to Enhance Cell-Selective Adhesion

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Rio Kurimoto

2016-01-01

Full Text Available Although surface immobilization of medical devices with bioactive molecules is one of the most widely used strategies to improve biocompatibility, the physicochemical properties of the biomaterials significantly impact the activity of the immobilized molecules. Herein we investigate the combinational effects of cell-selective biomolecules and the hydrophobicity/hydrophilicity of the polymeric substrate on selective adhesion of endothelial cells (ECs, fibroblasts (FBs, and smooth muscle cells (SMCs. To control the polymeric substrate, biomolecules are immobilized on thermoresponsive poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide (poly(NIPAAm-co-CIPAAm-grafted glass surfaces. By switching the molecular conformation of the biomolecule-immobilized polymers, the cell-selective adhesion performances are evaluated. In case of RGDS (Arg-Gly-Asp-Ser peptide-immobilized surfaces, all cell types adhere well regardless of the surface hydrophobicity. On the other hand, a tri-Arg-immobilized surface exhibits FB-selectivity when the surface is hydrophilic. Additionally, a tri-Ile-immobilized surface exhibits EC-selective cell adhesion when the surface is hydrophobic. We believe that the proposed concept, which is used to investigate the biomolecule-immobilized surface combination, is important to produce new biomaterials, which are highly demanded for medical implants and tissue engineering.

Use of magnetic forces to promote stem cell aggregation during differentiation, and cartilage tissue modeling.

Science.gov (United States)

Fayol, D; Frasca, G; Le Visage, C; Gazeau, F; Luciani, N; Wilhelm, C

2013-05-14

Magnetic forces induce cell condensation necessary for stem cell differentiation into cartilage and elicit the formation of a tissue-like structure: Magnetically driven fusion of aggregates assembled by micromagnets results in the formation of a continuous tissue layer containing abundant cartilage matrix. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Particle-in-cell simulations on spontaneous thermal magnetic field fluctuations

Energy Technology Data Exchange (ETDEWEB)

Simões, F. J. R. Jr.; Pavan, J. [Instituto de Física e Matemática, UFPel, Pelotas, RS (Brazil); Gaelzer, R.; Ziebell, L. F. [Instituto de Física, UFRGS, Porto Alegre, RS (Brazil); Yoon, P. H. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)

2013-10-15

In this paper an electromagnetic particle code is used to investigate the spontaneous thermal emission. Specifically we perform particle-in-cell simulations employing a non-relativistic isotropic Maxwellian particle distribution to show that thermal fluctuations are related to the origin of spontaneous magnetic field fluctuation. These thermal fluctuations can become seed for further amplification mechanisms and thus be considered at the origin of the cosmological magnetic field, at microgauss levels. Our numerical results are in accordance with theoretical results presented in the literature.

Functional magnetic resonance microscopy at single-cell resolution in Aplysia californica

Science.gov (United States)

Radecki, Guillaume; Nargeot, Romuald; Jelescu, Ileana Ozana; Le Bihan, Denis; Ciobanu, Luisa

2014-01-01

In this work, we show the feasibility of performing functional MRI studies with single-cell resolution. At ultrahigh magnetic field, manganese-enhanced magnetic resonance microscopy allows the identification of most motor neurons in the buccal network of Aplysia at low, nontoxic Mn2+ concentrations. We establish that Mn2+ accumulates intracellularly on injection into the living Aplysia and that its concentration increases when the animals are presented with a sensory stimulus. We also show that we can distinguish between neuronal activities elicited by different types of stimuli. This method opens up a new avenue into probing the functional organization and plasticity of neuronal networks involved in goal-directed behaviors with single-cell resolution. PMID:24872449

Kinetic of magnetic nanoparticles uptake evaluated by morphometry of mice peritoneal cells

International Nuclear Information System (INIS)

Silva, L.P.; Kuckelhaus, S.; Guedes, M.H.A.; Lacava, Z.G.M.; Tedesco, A.C.; Morais, P.C.; Azevedo, R.B.

2005-01-01

The development of magnetic fluids (MFs) has led to a wide range of new biomedical applications. Nevertheless, few studies have examined the kinetics of the magnetic nanoparticles (MNPs) internalization by phagocytes. In this study, we present morphometry as a method to quantify the cell surface covered by MNPs. The maximum cell surface covered by MNPs aggregates was 32.5% (8.5 min), 18.3% (24.1 min), and 18.0% (20.2 min) in DMSA, citric acid and dextran-coated MNPs, respectively. We concluded that the phagocytosis process of MNPs is strongly dependent upon the coating species

Synthesis of a new magnetic-MIP for the selective detection of 1-chloro-2,4-dinitrobenzene, a highly allergenic compound

Energy Technology Data Exchange (ETDEWEB)

Uzuriaga-Sánchez, Rosario Josefina [Department of Analytical Chemistry, Institute of Chemistry, State University of São Paulo (UNESP), 14801-970 Araraquara, SP (Brazil); Laboratory of Physical Chemistry Research, Faculty of Science, National University of Engineering, Av. Tupac Amaru 210, Rimac, Lima (Peru); Wong, Ademar; Khan, Sabir [Department of Analytical Chemistry, Institute of Chemistry, State University of São Paulo (UNESP), 14801-970 Araraquara, SP (Brazil); Pividori, Maria I. [Sensors and Biosensors Group, Department of Chemistry, Autonomous University of Barcelona (UAB), 08193, Bellaterra, Barcelona (Spain); Picasso, Gino, E-mail: gpicasso@uni.edu.pe [Laboratory of Physical Chemistry Research, Faculty of Science, National University of Engineering, Av. Tupac Amaru 210, Rimac, Lima (Peru); Sotomayor, Maria D.P.T., E-mail: mpilar@iq.unesp.br [Department of Analytical Chemistry, Institute of Chemistry, State University of São Paulo (UNESP), 14801-970 Araraquara, SP (Brazil)

2017-05-01

Molecularly imprinted polymers (MIPs) in combination with magnetic nanoparticles, in a core@shell format, were studied for selective detection of 1-chloro-2,4-dinitrobenzene (CDNB), a powerful allergenic substance. Magnetic nanoparticles were prepared by the co-precipitation method and mixed with oleic acid (OA). This material was then encapsulated in three types of hydrophobic polymeric matrix, poly-(MA-co-EDGMA), poly-(AA-co-EDGMA), and poly-(1-VN-co-EDGMA), by the mini-emulsion method. These matrices were used due to their ability to interact specifically with the functional groups of the analyte. Finally, the MIP-CDNB was obtained on the magnetic-hydrophobic surfaces using precipitation polymerization in the presence of the analyte. XRD diffraction patterns suggested the presence of magnetite in the composite and SEM analysis revealed a nanoparticle size between 10 and 18 nm. Under the optimized adsorption conditions, the magnetic-MIP material showed a higher adsorption capacity (5.1 mg g{sup −1}) than its non-magnetic counterpart (4.2 mg g{sup −1}). In tests of the selectivity of the magnetic-MIP towards CDNB, α-values of 2.5 and 10.4, respectively, were obtained for dichlorophenol and o-nitrophenol, two structurally similar compounds, and no adsorption was observed for any other non-analogous analyte. The magnetic-MIP and magnetic-NIP were applied using water enriched with 0.5 mg L{sup −1} of CDNB, achieving recovery values of 83.8(± 0.8)% and 66(± 1)%, respectively, revealing the suitability of the material for detection of CDNB. - Highlights: • Novel engineered magnetic nanoparticles selective for allergenic CDBN with potential environmental impact • Morphological and molecular recognition properties of imprinted materials • Direct magnetic separation, removal efficiency, and active remediation of real samples.

Synthesis of a new magnetic-MIP for the selective detection of 1-chloro-2,4-dinitrobenzene, a highly allergenic compound

International Nuclear Information System (INIS)

Uzuriaga-Sánchez, Rosario Josefina; Wong, Ademar; Khan, Sabir; Pividori, Maria I.; Picasso, Gino; Sotomayor, Maria D.P.T.

2017-01-01

Molecularly imprinted polymers (MIPs) in combination with magnetic nanoparticles, in a core@shell format, were studied for selective detection of 1-chloro-2,4-dinitrobenzene (CDNB), a powerful allergenic substance. Magnetic nanoparticles were prepared by the co-precipitation method and mixed with oleic acid (OA). This material was then encapsulated in three types of hydrophobic polymeric matrix, poly-(MA-co-EDGMA), poly-(AA-co-EDGMA), and poly-(1-VN-co-EDGMA), by the mini-emulsion method. These matrices were used due to their ability to interact specifically with the functional groups of the analyte. Finally, the MIP-CDNB was obtained on the magnetic-hydrophobic surfaces using precipitation polymerization in the presence of the analyte. XRD diffraction patterns suggested the presence of magnetite in the composite and SEM analysis revealed a nanoparticle size between 10 and 18 nm. Under the optimized adsorption conditions, the magnetic-MIP material showed a higher adsorption capacity (5.1 mg g −1 ) than its non-magnetic counterpart (4.2 mg g −1 ). In tests of the selectivity of the magnetic-MIP towards CDNB, α-values of 2.5 and 10.4, respectively, were obtained for dichlorophenol and o-nitrophenol, two structurally similar compounds, and no adsorption was observed for any other non-analogous analyte. The magnetic-MIP and magnetic-NIP were applied using water enriched with 0.5 mg L −1 of CDNB, achieving recovery values of 83.8(± 0.8)% and 66(± 1)%, respectively, revealing the suitability of the material for detection of CDNB. - Highlights: • Novel engineered magnetic nanoparticles selective for allergenic CDBN with potential environmental impact • Morphological and molecular recognition properties of imprinted materials • Direct magnetic separation, removal efficiency, and active remediation of real samples

Cuprous oxide nanoparticles selectively induce apoptosis of tumor cells

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Wang Y

2012-05-01

Full Text Available Ye Wang,1,2,* Xiao-Yuan Zi,1,* Juan Su,1 Hong-Xia Zhang,1 Xin-Rong Zhang,3 Hai-Ying Zhu,1 Jian-Xiu Li,1 Meng Yin,3 Feng Yang,3 Yi-Ping Hu,11Department of Cell Biology, 2School of Clinical Medicine, 3Department of Pharmaceuticals, Second Military Medical University, Shanghai, People's Republic of China*Authors contributed equally.Abstract: In the rapid development of nanoscience and nanotechnology, many researchers have discovered that metal oxide nanoparticles have very useful pharmacological effects. Cuprous oxide nanoparticles (CONPs can selectively induce apoptosis and suppress the proliferation of tumor cells, showing great potential as a clinical cancer therapy. Treatment with CONPs caused a G1/G0 cell cycle arrest in tumor cells. Furthermore, CONPs enclosed in vesicles entered, or were taken up by mitochondria, which damaged their membranes, thereby inducing apoptosis. CONPs can also produce reactive oxygen species (ROS and initiate lipid peroxidation of the liposomal membrane, thereby regulating many signaling pathways and influencing the vital movements of cells. Our results demonstrate that CONPs have selective cytotoxicity towards tumor cells, and indicate that CONPs might be a potential nanomedicine for cancer therapy.Keywords: nanomedicine, selective cytotoxicity, apoptosis, cell cycle arrest, mitochondrion-targeted nanomaterials

Resonant cell of a double nuclear electron resonance spectrometer for performance in a 120-350 Gs magnetic field

International Nuclear Information System (INIS)

Baldin, V.I.; Stepanov, A.P.

1976-01-01

Spectrometer double-frequency resonance cell construction of a double nuclear electron resonance for operation in 120-350 Gs magnetic fields is described. The cell has been developed from a special decimeter resonator with a concentrated capacitance. The electric and magnetic components of a high frequency field are efficiently divided in the separator. Therefore, the insertion of a measuring coil and a sample in the maximum of the magnetic component of the field does not practically affect the distribution and parameters of the high-frequency field. The double-frequency resonance cell proposed provides for a higher accuracy of measuring amplifications of the nuclear magnetic resonance signals when there is the overhauzer effect for 120-350 Gs magnetic fields

Voxel-wise prostate cell density prediction using multiparametric magnetic resonance imaging and machine learning.

Science.gov (United States)

Sun, Yu; Reynolds, Hayley M; Wraith, Darren; Williams, Scott; Finnegan, Mary E; Mitchell, Catherine; Murphy, Declan; Haworth, Annette

2018-04-26

There are currently no methods to estimate cell density in the prostate. This study aimed to develop predictive models to estimate prostate cell density from multiparametric magnetic resonance imaging (mpMRI) data at a voxel level using machine learning techniques. In vivo mpMRI data were collected from 30 patients before radical prostatectomy. Sequences included T2-weighted imaging, diffusion-weighted imaging and dynamic contrast-enhanced imaging. Ground truth cell density maps were computed from histology and co-registered with mpMRI. Feature extraction and selection were performed on mpMRI data. Final models were fitted using three regression algorithms including multivariate adaptive regression spline (MARS), polynomial regression (PR) and generalised additive model (GAM). Model parameters were optimised using leave-one-out cross-validation on the training data and model performance was evaluated on test data using root mean square error (RMSE) measurements. Predictive models to estimate voxel-wise prostate cell density were successfully trained and tested using the three algorithms. The best model (GAM) achieved a RMSE of 1.06 (± 0.06) × 10 3 cells/mm 2 and a relative deviation of 13.3 ± 0.8%. Prostate cell density can be quantitatively estimated non-invasively from mpMRI data using high-quality co-registered data at a voxel level. These cell density predictions could be used for tissue classification, treatment response evaluation and personalised radiotherapy.

Development of magnetic jxB sensor

International Nuclear Information System (INIS)

Kasai, Satoshi; Ishitsuka, Etsuo

2001-12-01

The improved mechanical sensor, i.e. magnetic jxB sensor (a mechanical sensor and a part of the steady state hybrid-type magnetic sensor) has been designed. The basic structure of the sensor is similar to the previously developed sensor (old sensor) in EDA phase. In this design, the neutron resistant materials are selected for the load cell (strain gauge and sensor beam) and sensing coil/frame. In order to reduce temperature drift of the sensor signal, four strain gauges with the same electrical property and geometrical size are bonded on the sensor beam by using Al 2 O 3 plasma spraying process, i.e., a couple of strain gauges is bonded on one side of the beam and another couple of gauges is bonded on the other side. These four strain gauges form an electrical bridge circuit. The zero-level drift of the output of the load cell used in the magnetic jxB sensor was reduced to about 1/20 compared with the old sensor. The temperature dependence of the output of the load cell is small. The linearity of the output of the load cell against weight was obtained. A non-linearity was observed in the sensitivity of the magnetic jxB sensor. The deviation of sensitivity from the fitting line was less than 7% in the high magnetic field region. The neutron irradiation effect on sensitivity of the sensor was investigated. The sensitivity of the sensor was gradually decreased by ∼30% at neutron fluence of (1.8-2.8)x10 23 n/m 2 in the high magnetic field. During irradiation, the non-linearity was observed in the sensitivity. (author)

Long-term MRI cell tracking after intraventricular delivery in a patient with global cerebral ischemia and prospects for magnetic navigation of stem cells within the CSF.

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Miroslaw Janowski

Full Text Available The purpose of the study was to evaluate the long-term clinical tracking of magnetically labeled stem cells after intracerebroventricular transplantation as well as to investigate in vitro feasibility for magnetic guidance of cell therapy within large fluid compartments.After approval by our Institutional Review Board, an 18-month-old patient, diagnosed as being in a vegetative state due to global cerebral ischemia, underwent cell transplantation to the frontal horn of the lateral ventricle, with umbilical cord blood-derived stem cells labeled with superparamagnetic iron oxide (SPIO contrast agent. The patient was followed over 33 months with clinical examinations and MRI. To evaluate the forces governing the distribution of cells within the fluid compartment of the ventricular system in vivo, a gravity-driven sedimentation assay and a magnetic field-driven cell attraction assay were developed in vitro.Twenty-four hours post-transplantation, MR imaging (MRI was able to detect hypointense cells in the occipital horn of the lateral ventricle. The signal gradually decreased over 4 months and became undetectable at 33 months. In vitro, no significant difference in cell sedimentation between SPIO-labeled and unlabeled cells was observed (p = NS. An external magnet was effective in attracting cells over distances comparable to the size of human lateral ventricles.MR imaging of SPIO-labeled cells allows monitoring of cells within lateral ventricles. While the initial biodistribution is governed by gravity-driven sedimentation, an external magnetic field may possibly be applied to further direct the distribution of labeled cells within large fluid compartments such as the ventricular system.

The effects of functional magnetic nanotubes with incorporated nerve growth factor in neuronal differentiation of PC12 cells

International Nuclear Information System (INIS)

Xie Jining; Chen Linfeng; Varadan, Vijay K; Yancey, Justin; Srivatsan, Malathi

2008-01-01

In this in vitro study the efficiency of magnetic nanotubes to bind with nerve growth factor (NGF) and the ability of NGF-incorporated magnetic nanotubes to release the bound NGF are investigated using rat pheochromocytoma cells (PC12 cells). It is found that functional magnetic nanotubes with NGF incorporation enabled the differentiation of PC12 cells into neurons exhibiting growth cones and neurite outgrowth. Microscope observations show that filopodia extending from neuron growth cones were in close proximity to the NGF-incorporated magnetic nanotubes, at times appearing to extend towards or into them. These results show that magnetic nanotubes can be used as a delivery vehicle for NGF and thus may be exploited in attempts to treat neurodegenerative disorders such as Parkinson's disease with neurotrophins. Further neurite outgrowth can be controlled by manipulating magnetic nanotubes with external magnetic fields, thus helping in directed regeneration

In vivo quantification of magnetically labelled cells by MRI relaxometry.

Science.gov (United States)

Gimenez, Ulysse; Lajous, Hélène; El Atifi, Michèle; Bidart, Marie; Auboiroux, Vincent; Fries, Pascal Henry; Berger, François; Lahrech, Hana

2016-11-01

Cellular MRI, which visualizes magnetically labelled cells (cells*), is an active research field for in vivo cell therapy and tracking. The simultaneous relaxation rate measurements (R 2 *, R 2 , R 1 ) are the basis of a quantitative cellular MRI method proposed here. U937 cells were labelled with Molday ION Rhodamine B, a bi-functional superparamagnetic and fluorescent nanoparticle (U937*). U937* viability and proliferation were not affected in vitro. In vitro relaxometry was performed in a cell concentration range of [2.5 × 10 4 -10 8 ] cells/mL. These measurements show the existence of complementary cell concentration intervals where these rates vary linearly. The juxtaposition of these intervals delineates a wide cell concentration range over which one of the relaxation rates in a voxel of an in vivo image can be converted into an absolute cell concentration. The linear regime was found at high concentrations for R 1 in the range of [10 6 - 2 × 10 8 ] cells/mL, at intermediate concentrations for R 2 in [2.5 × 10 5 - 5 × 10 7 ] cells/mL and at low concentrations for R 2 * in [8 × 10 4 - 5 × 10 6 ] cells/mL. In vivo relaxometry was performed in a longitudinal study, with labelled U937 cells injected into a U87 glioma mouse model. Using in vitro data, maps of in vivo U937* concentrations were obtained by converting one of the in vivo relaxation rates to cell concentration maps. MRI results were compared with the corresponding optical images of the same brains, showing the usefulness of our method to accurately follow therapeutic cell biodistribution in a longitudinal study. Results also demonstrate that the method quantifies a large range of magnetically labelled cells*. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

An Improved Method for Magnetic Nanocarrier Drug Delivery across the Cell Membrane

Directory of Open Access Journals (Sweden)

Behzad Mehrafrooz

2018-01-01

Full Text Available One of the crucial issues in the pharmacological field is developing new drug delivery systems. The main concern is to develop new methods for improving the drug delivery efficiencies such as low disruptions, precise control of the target of delivery and drug sustainability. Nowadays, there are many various methods for drug delivery systems. Carbon-based nanocarriers are a new efficient tool for translocating drug into the defined area or cells inside the body. These nanocarriers can be functionalized with proteins, peptides and used to transport their freight to cells or defined areas. Since functionalized carbon-based nanocarriers show low toxicity and high biocompatibility, they are used in many nanobiotechnology fields. In this study, different shapes of nanocarrier are investigated, and the suitable magnetic field, which is applied using MRI for the delivery of the nanocarrier, is proposed. In this research, based on the force required to cross the membrane and MD simulations, the optimal magnetic field profile is designed. This optimal magnetic force field is derived from the mathematical model of the system and magnetic particle dynamics inside the nanocarrier. The results of this paper illustrate the effects of the nanocarrier’s shapes on the percentage of success in crossing the membrane and the optimal required magnetic field.

Effect of 0.4 mT power frequency magnetic field on F-actin assembly of CHL cells

International Nuclear Information System (INIS)

Chu Keping; Cai Zhiyin; Zhang Yukun; Xia Nuohong

2007-01-01

Objective: To investigate the effect of 0.4mT power frequency magnetic field on the microfilament (F- actin) assembly of Chinese hamster lung (CHL) cells. Methods: F-actin were marked with immunohistochemical method, then observed under a confocal microscope. The content of ECFRs in the preparation of the detergent-insoluble cytoskeleton was measured with Western-blotting. Results: The stress fiber's of CHL cells decreased after exposure to 0.4mT power frequency magnetic field for 30min, as well as after treatment with epidermal growth factor (ECF) of 50nM. Filopodias appeared at the periphery after exposure to magnetic field as well as treatment with EGF. The EGF receptor mass associated with the detergent-insoluble cytoskeleton increased after exposure to magnetic field as well as treatment with EGF. Conclusion: 0.4mT power frequency magnetic field induced assembly of F-actin in CHL cells. The change induced by magnetic field would be related to clustering of EGFR induced by magnetic field and passing the signal down. (authors)

Particle-In-Cell Simulations of the Solar Wind Interaction with Lunar Crustal Magnetic Anomalies: Magnetic Cusp Regions

Science.gov (United States)

Poppe, A. R.; Halekas, J. S.; Delory, G. T.; Farrell, W. M.

2012-01-01

As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent magnetic fields. These magnetic fields are small-scale, highly non-dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can reflect solar wind protons via a combination of magnetic and electrostatic reflection; however, analyses of surface properties have suggested that protons may still access the lunar surface in the cusp regions of crustal magnetic fields. In this first report from a planned series of studies, we use a 1 1/2-dimensional, electrostatic particle-in-cell code to model the self-consistent interaction between the solar wind, the cusp regions of lunar crustal remanent magnetic fields, and the lunar surface. We describe the self-consistent electrostatic environment within crustal cusp regions and discuss the implications of this work for the role that crustal fields may play regulating space weathering of the lunar surface via proton bombardment.

Selective uptake of boronophenylalanine by glioma stem/progenitor cells

International Nuclear Information System (INIS)

Sun, Ting; Zhou, Youxin; Xie, Xueshun; Chen, Guilin; Li, Bin; Wei, Yongxin; Chen, Jinming; Huang, Qiang; Du, Ziwei

2012-01-01

The success of boron neutron capture therapy (BNCT) depends on the amount of boron in cells and the tumor/blood and tumor/(normal tissue) boron concentration ratios. For the first time, measurements of boron uptake in both stem/progenitor and differentiated glioma cells were performed along with measurements of boron biodistribution in suitable animal models. In glioma stem/progenitor cells, the selective accumulation of boronophenylalanine (BPA) was lower, and retention of boron after BPA removal was longer than in differentiated glioma cells in vitro. However, boron biodistribution was not statistically significantly different in mice with xenografts. - Highlights: ► Uptake of BPA was analyzed in stem/progenitor and differentiated glioma cells. ► Selective accumulation of BPA was lower in glioma stem/progenitor cells. ► Retention of boron after BPA removal was longer in glioma stem/progenitor cells. ► Boron biodistribution was not statistically different in mice with xenografts.

Pulsed magnetization transfer contrast MRI by a sequence with water selective excitation

Energy Technology Data Exchange (ETDEWEB)

Schick, F. [Univ. of Tuebingen (Germany)

1996-01-01

A water selective SE imaging sequence was developed providing suitable properties for the assessment of magnetization transfer (MT) effects in tissues with considerable amounts of fat. The sequence with water selective excitation and slice selective refocusing combines the following features: The RIF exposure on the macromolecular protons is relatively low for single slice imaging without MT prepulses, since no additional pulses for fat saturation are necessary. Water selection by frequency selective excitation diminishes faults in the subtraction of images recorded with and without MT prepulses (which might arise from movements). High differences in the signal amplitudes from hyaline cartilage and muscle tissue were obtained comparing images recorded with irradiation of the series of prepulses for MT and those lacking MT prepulses. Utilizations of the described water selective approach for the assessment of MT effects in lesions of cartilage and bone are demonstrated. MT saturation was also examined in muscles with fatty degeneration of patients suffering from progressive muscular dystrophy. The described technique allows determination of MT effects with good precision in a single slice, especially in regions with dominating fat signals. 22 refs., 5 figs.

Cell adsorption and selective desorption for separation of microbial cells by using chitosan-immobilized silica.

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Kubota, Munehiro; Matsui, Masayoshi; Chiku, Hiroyuki; Kasashima, Nobuyuki; Shimojoh, Manabu; Sakaguchi, Kengo

2005-12-01

Cell adsorption and selective desorption for separation of microbial cells were conducted by using chitosan-immobilized silica (CIS). When chitosan was immobilized onto silica surfaces with glutaraldehyde, bacterial cells adsorbed well and retained viability. Testing of the adsorption and desorption ability of CIS using various microbes such as Escherichia coli, Aeromonas hydrophila, Pseudomonas aeruginosa, Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Lactobacillus casei, Streptococcus mutans, Streptococcus sobrinus, Streptococcus salivarius, Saccharomyces cerevisiae, Saccharomyces ludwigii, and Schizosaccharomyces pombe revealed that most microbes could be adsorbed and selectively desorbed under different conditions. In particular, recovery was improved when L-cysteine was added. A mixture of two bacterial strains adsorbed onto CIS could also be successfully separated by use of specific solutions for each strain. Most of the desorbed cells were alive. Thus, quantitative and selective fractionation of cells is readily achievable by employing chitosan, a known antibacterial material.

Feasibility study of red blood cell debulking by magnetic field-flow fractionation with step-programmed flow.

Science.gov (United States)

Moore, Lee R; Williams, P Stephen; Nehl, Franziska; Abe, Koji; Chalmers, Jeffrey J; Zborowski, Maciej

2014-02-01

Emerging applications of rare cell separation and analysis, such as separation of mature red blood cells from hematopoietic cell cultures, require efficient methods of red blood cell (RBC) debulking. We have tested the feasibility of magnetic RBC separation as an alternative to centrifugal separation using an approach based on the mechanism of magnetic field-flow fractionation (MgFFF). A specially designed permanent magnet assembly generated a quadrupole field having a maximum field of 1.68 T at the magnet pole tips, zero field at the aperture axis, and a nearly constant radial field gradient of 1.75 T/mm (with a negligible angular component) inside a cylindrical aperture of 1.9 mm (diameter) and 76 mm (length). The cell samples included high-spin hemoglobin RBCs obtained by chemical conversion of hemoglobin to methemoglobin (met RBC) or by exposure to anoxic conditions (deoxy RBC), low-spin hemoglobin obtained by exposure of RBC suspension to ambient air (oxy RBC), and mixtures of deoxy RBC and cells from a KG-1a white blood cell (WBC) line. The observation that met RBCs did not elute from the channel at the lower flow rate of 0.05 mL/min applied for 15 min but quickly eluted at the subsequent higher flow rate of 2.0 mL/min was in agreement with FFF theory. The well-defined experimental conditions (precise field and flow characteristics) and a well-established FFF theory verified by studies with model cell systems provided us with a strong basis for making predictions about potential practical applications of the magnetic RBC separation.

Purification of human induced pluripotent stem cell-derived neural precursors using magnetic activated cell sorting.

Science.gov (United States)

Rodrigues, Gonçalo M C; Fernandes, Tiago G; Rodrigues, Carlos A V; Cabral, Joaquim M S; Diogo, Maria Margarida

2015-01-01

Neural precursor (NP) cells derived from human induced pluripotent stem cells (hiPSCs), and their neuronal progeny, will play an important role in disease modeling, drug screening tests, central nervous system development studies, and may even become valuable for regenerative medicine treatments. Nonetheless, it is challenging to obtain homogeneous and synchronously differentiated NP populations from hiPSCs, and after neural commitment many pluripotent stem cells remain in the differentiated cultures. Here, we describe an efficient and simple protocol to differentiate hiPSC-derived NPs in 12 days, and we include a final purification stage where Tra-1-60+ pluripotent stem cells (PSCs) are removed using magnetic activated cell sorting (MACS), leaving the NP population nearly free of PSCs.

Magnetically responsive yeast cells: methods of preparation and applications

Czech Academy of Sciences Publication Activity Database

Šafařík, Ivo; Maděrová, Zdeňka; Pospišková, K.; Horská, Kateřina; Šafaříková, Miroslava

2015-01-01

Roč. 32, č. 1 (2015), s. 227-237 ISSN 0749-503X R&D Projects: GA MŠk(CZ) LD13023; GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : yeast cells * Saccharomyces * Kluyveromyces * Rhodotorula * Yarrowia * magnetic modification Subject RIV: CE - Biochemistry Impact factor: 2.259, year: 2015

Fluorescein isothiocyanate labeled, magnetic nanoparticles conjugated D-penicillamine-anti-metadherin and in vitro evaluation on breast cancer cells

International Nuclear Information System (INIS)

Akca, Ozlet; Unak, Perihan; Medine, E. Ylker; Sakarya, Serhan; Ozdemir, Caglar; Timur, Suna

2011-01-01

Silane modified magnetic nanoparticles were prepared after capped with silica generated from the hydrolyzation of tetraethyl orthosilicate (TEOS). Amino silane (SG-Si900) was added to this solution for surface modification of silica coated magnetic particles. Finally, D-penicillamine (D-PA)-antimetadherin (anti-MTDH) was covalently linked to the amine group using glutaraldehyde as cross-linker. Magnetic nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and atomic force microscopy (AFM). AFM results showed that particles are nearly monodisperse, and the average size of particles was 40 to 50 nm. An amino acid derivative D-PA was conjugated anti-MTDH, which results the increase of uptaking potential of a conjugated agent, labelled fluorescein isothiocyanate (FITC) and then conjugated to the magnetic nanoparticles. In vitro evaluation of the conjugated D-PA-anti-MTDH-FITC to magnetic nanoparticle was studied on MCF-7 breast cancer cell lines. Fluorescence microscopy images of cells after incubation of the sample were obtained to monitor the interaction of the sample with the cancerous cells. Incorporation on cells of FITC labeled and magnetic nanoparticles conjugated D-PA-anti-MTDH was found higher than FITC labeled D-PA-anti-MTDH. The results show that magnetic properties and application of magnetic field increased incorporation rates. The obtained D-PA-anti-MTDH-magnetic nanoparticles-FITC complex has been used for in vitro imaging of breast cancer cells. FITC labeled and magnetic nanoparticles conjugated D-PA-anti-MTDH may be useful as a new class of scintigraphic agents. Results of this study are sufficiently encouraging to bring about further evaluation of this and related compounds for ultraviolet magnetic resonance (UV-MR) dual imaging. (author)

Magnetic capture of polydopamine-encapsulated Hela cells for the analysis of cell surface proteins.

Science.gov (United States)

Liu, Yiying; Yan, Guoquan; Gao, Mingxia; Zhang, Xiangmin

2018-02-10

A novel method to characterize cell surface proteins and complexes has been developed. Polydopamine (PDA)-encapsulated Hela cells were prepared for plasma membrane proteome research. Since the PDA protection, the encapsulated cells could be maintained for more than two weeks. Amino groups functionalized magnetic nanoparticles were also used for cell capture by the reaction with the PDA coatings. Plasma membrane fragments were isolated and enriched with assistance of an external magnetic field after disruption of the coated cells by ultrasonic treatment. Plasma membrane proteins (PMPs) and complexes were well preserved on the fragments and identified by shot-gun proteomic analytical strategy. 385 PMPs and 1411 non-PMPs were identified using the method. 85.2% of these PMPs were lipid-raft associated proteins. Ingenuity Pathway Analysis was employed for bio-information extraction from the identified proteins. It was found that 653 non-PMPs had interactions with 140 PMPs. Among them, epidermal growth factor receptor and its complexes, and a series of important pathways including STAT3 pathway were observed. All these results demonstrated that the new approach is of great importance in applying to the research of physiological function and mechanism of the plasma membrane proteins. This work developed a novel strategy for the proteomic analysis of cell surface proteins. According to the results, 73.3% of total identified proteins were lipid-raft associated proteins, which imply that the proposed method is of great potential in the identification of lipid-raft associated proteins. In addition, a series of protein-protein interactions and pathways related to Hela cells were pointed out. All these results demonstrated that our proposed approach is of great importance and could well be applied to the physiological function and mechanism research of plasma membrane proteins. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetic tagging of cell-derived microparticles: new prospects for imaging and manipulation of these mediators of biological information.

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Vats, Nidhi; Wilhelm, Claire; Rautou, Pierre-Emmanuel; Poirier-Quinot, Marie; Péchoux, Christine; Devue, Cécile; Boulanger, Chantal M; Gazeau, Florence

2010-07-01

Submicron membrane fragments termed microparticles (MPs), which are released by apoptotic or activated cells, are newly considered as vectors of biological information and actors of pathology development. We propose the tagging of MPs with magnetic nanoparticles as a new approach allowing imaging, manipulation and targeting of cell-derived MPs. MPs generated in vitro from human endothelial cells or isolated from atherosclerotic plaques were labeled using citrate-coated 8 nm iron-oxide nanoparticles. MPs were tagged with magnetic nanoparticles on their surface and detected as Annexin-V positive by flow cytometry. Labeled MPs could be mobilized, isolated and manipulated at a distance in a magnetic field gradient. Magnetic mobility of labeled MPs was quantified by micromagnetophoresis. Interactions of labeled MPs with endothelial cells could be triggered and modulated by magnetic guidance. Nanoparticles served as tracers at different scales: at the subcellular level by electron microscopy, at the cellular level by histology and at the macroscopic level by MRI. Magnetic labeling of biogenic MPs opens new prospects for noninvasive monitoring and distal manipulations of these biological effectors.

Cuprous oxide nanoparticles selectively induce apoptosis of tumor cells

Science.gov (United States)

Wang, Ye; Zi, Xiao-Yuan; Su, Juan; Zhang, Hong-Xia; Zhang, Xin-Rong; Zhu, Hai-Ying; Li, Jian-Xiu; Yin, Meng; Yang, Feng; Hu, Yi-Ping

2012-01-01

In the rapid development of nanoscience and nanotechnology, many researchers have discovered that metal oxide nanoparticles have very useful pharmacological effects. Cuprous oxide nanoparticles (CONPs) can selectively induce apoptosis and suppress the proliferation of tumor cells, showing great potential as a clinical cancer therapy. Treatment with CONPs caused a G1/G0 cell cycle arrest in tumor cells. Furthermore, CONPs enclosed in vesicles entered, or were taken up by mitochondria, which damaged their membranes, thereby inducing apoptosis. CONPs can also produce reactive oxygen species (ROS) and initiate lipid peroxidation of the liposomal membrane, thereby regulating many signaling pathways and influencing the vital movements of cells. Our results demonstrate that CONPs have selective cytotoxicity towards tumor cells, and indicate that CONPs might be a potential nanomedicine for cancer therapy. PMID:22679374

Tax gene expression and cell cycling but not cell death are selected during HTLV-1 infection in vivo

Directory of Open Access Journals (Sweden)

Pinatel Christiane

2010-03-01

Full Text Available Abstract Background Adult T cell leukemia results from the malignant transformation of a CD4+ lymphoid clone carrying an integrated HTLV-1 provirus that has undergone several oncogenic events over a 30-60 year period of persistent clonal expansion. Both CD4+ and CD8+ lymphocytes are infected in vivo; their expansion relies on CD4+ cell cycling and on the prevention of CD8+ cell death. Cloned infected CD4+ but not CD8+ T cells from patients without malignancy also add up nuclear and mitotic defects typical of genetic instability related to theexpression of the virus-encoded oncogene tax. HTLV-1 expression is cancer-prone in vitro, but in vivo numerous selection forces act to maintain T cell homeostasis and are possibly involved in clonal selection. Results Here we demonstrate that the HTLV-1 associated CD4+ preleukemic phenotype and the specific patterns of CD4+ and CD8+ clonal expansion are in vivo selected processes. By comparing the effects of recent (1 month experimental infections performed in vitro and those observed in cloned T cells from patients infected for >6-26 years, we found that in chronically HTLV-1 infected individuals, HTLV-1 positive clones are selected for tax expression. In vivo, infected CD4+ cells are positively selected for cell cycling whereas infected CD8+ cells and uninfected CD4+ cells are negatively selected for the same processes. In contrast, the known HTLV-1-dependent prevention of CD8+ T cell death pertains to both in vivo and in vitro infected cells. Conclusions Therefore, virus-cell interactions alone are not sufficient to initiate early leukemogenesis in vivo.

Design of magnetic flywheel control for performance improvement of fuel cells used in vehicles

International Nuclear Information System (INIS)

Huang, Chung-Neng; Chen, Yui-Sung

2017-01-01

Because hydrogen can be extracted naturally and stored for a long time, different types of fuel cells have been developed to generate clean power, particularly for use in vehicles. However, the power demand of a running vehicle leads to unstable and irregular loading of fuel cells. This not only reduces fuel cell lifespan and efficiency but also affects driving safety when the slow output response cannot satisfy an abrupt increase in power demand. Magnetic flywheels with characteristics such as high energy density, high-speed charging ability, and low loss have been extensively used in Formula One cars. This study developed a hybrid powertrain in which a magnetic flywheel system (MFS) is integrated with the fuel cells to solve the aforementioned problems. Moreover, an auto-tuning proportional–integral–derivative (PID) controller based on the controls of a multiple adaptive neuro-fuzzy interference system and particle swarm optimization was designed for MFS control. Furthermore, MATLAB/Simulink simulations considering an FTP-75 urban driving cycle were conducted, and a variability improvement of approximately 27.3% in fuel cell output was achieved. - Highlights: • A hybrid powertrain integrating the magnetic flywheel and fuel cells is proposed. • An auto-tuning PID controller is designed for MFS control. • The MIMO-ANFIS and PSO based optimal control is realized. • A 27.3% improvement in the output variability of fuel cell is achieved under control.

3D cellular structures and co-cultures formed through the contactless magnetic manipulation of cells on adherent surfaces.

Science.gov (United States)

Abdel Fattah, Abdel Rahman; Mishriki, Sarah; Kammann, Tobias; Sahu, Rakesh P; Geng, Fei; Puri, Ishwar K

2018-02-27

A magnet array is employed to manipulate diamagnetic cells that are contained in paramagnetic medium to demonstrate for the first time the contactless bioprinting of three-dimensional (3D) cellular structures and co-cultures of breast cancer MCF-7 and endothelial HUVEC at prescribed locations on tissue culture treated well plates. Sequential seeding of different cell lines and the spatial displacement of the magnet array creates co-cultured cellular structures within a well without using physically intrusive well inserts. Both monotypic and co-culture experiments produce morphologically rich 3D cell structures that are otherwise absent in regular monolayer cell cultures. The magnetic contactless bioprinting of cells provides further insight into cell behaviour, invasion strategies and transformations that are useful for potential applications in drug screening, 3D cell culture formation and tissue engineering.

Application of pulsed-magnetic field enhances non-viral gene delivery in primary cells from different origins

Energy Technology Data Exchange (ETDEWEB)

Kamau Chapman, Sarah W. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstr. 190, 8057 Zurich (Switzerland); Hassa, Paul O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstr. 190, 8057 Zurich (Switzerland); European Molecular Biology Laboratory (EMBL) Heidelberg, Meyerhofstrasse 1, 69117 Heidelberg (Germany); Koch-Schneidemann, Sabine; Rechenberg, Brigitte von [Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty Zurich, University of Zurich, Winterthurerstr. 260, 8057 Zurich (Switzerland); Hofmann-Amtenbrink, Margarethe [MatSearch, Chemin Jean Pavillard 14, 1009 Pully (Switzerland); Steitz, Benedikt; Petri-Fink, Alke; Hofmann, Heinrich [Laboratory of Powder Technology, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Hottiger, Michael O. [Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstr. 190, 8057 Zurich (Switzerland)], E-mail: hottiger@vetbio.uzh.ch

2008-04-15

Primary cell lines are more difficult to transfect when compared to immortalized/transformed cell lines, and hence new techniques are required to enhance the transfection efficiency in these cells. We isolated and established primary cultures of synoviocytes, chondrocytes, osteoblasts, melanocytes, macrophages, lung fibroblasts, and embryonic fibroblasts. These cells differed in several properties, and hence were a good representative sample of cells that would be targeted for expression and delivery of therapeutic genes in vivo. The efficiency of gene delivery in all these cells was enhanced using polyethylenimine-coated polyMAG magnetic nanoparticles, and the rates (17-84.2%) surpassed those previously achieved using other methods, especially in cells that are difficult to transfect. The application of permanent and pulsating magnetic fields significantly enhanced the transfection efficiencies in synoviocytes, chondrocytes, osteoblasts, melanocytes and lung fibroblasts, within 5 min of exposure to these magnetic fields. This is an added advantage for future in vivo applications, where rapid gene delivery is required before systemic clearance or filtration of the gene vectors occurs.

Cell type-specific response to high intracellular loading of polyacrylic acid-coated magnetic nanoparticles

Science.gov (United States)

Lojk, Jasna; Bregar, Vladimir B; Rajh, Maruša; Miš, Katarina; Kreft, Mateja Erdani; Pirkmajer, Sergej; Veranič, Peter; Pavlin, Mojca

2015-01-01

Magnetic nanoparticles (NPs) are a special type of NP with a ferromagnetic, electron-dense core that enables several applications such as cell tracking, hyperthermia, and magnetic separation, as well as multimodality. So far, superparamagnetic iron oxide NPs (SPIONs) are the only clinically approved type of metal oxide NPs, but cobalt ferrite NPs have properties suitable for biomedical applications as well. In this study, we analyzed the cellular responses to magnetic cobalt ferrite NPs coated with polyacrylic acid (PAA) in three cell types: Chinese Hamster Ovary (CHO), mouse melanoma (B16) cell line, and primary human myoblasts (MYO). We compared the internalization pathway, intracellular trafficking, and intracellular fate of our NPs using fluorescence and transmission electron microscopy (TEM) as well as quantified NP uptake and analyzed uptake dynamics. We determined cell viability after 24 or 96 hours’ exposure to increasing concentrations of NPs, and quantified the generation of reactive oxygen species (ROS) upon 24 and 48 hours’ exposure. Our NPs have been shown to readily enter and accumulate in cells in high quantities using the same two endocytic pathways; mostly by macropinocytosis and partially by clathrin-mediated endocytosis. The cell types differed in their uptake rate, the dynamics of intracellular trafficking, and the uptake capacity, as well as in their response to higher concentrations of internalized NPs. The observed differences in cell responses stress the importance of evaluation of NP–cell interactions on several different cell types for better prediction of possible toxic effects on different cell and tissue types in vivo. PMID:25733835

A Traceless Selection: Counter-selection System That Allows Efficient Generation of Transposon and CRISPR-modified T-cell Products

Directory of Open Access Journals (Sweden)

Riccardo Mezzadra

2016-01-01

Full Text Available Recent years have seen major breakthroughs in genome-engineering systems, such as transposon-mediated gene delivery systems and CRISPR-Cas9-mediated genome-editing tools. In these systems, transient expression of auxiliary genes is responsible for permanent genomic modification. For both systems, it would be valuable to select for cells that are likely to undergo stable genome modification. Importantly, in particular for clinical applications of genome-engineered cell products, it will also be of importance to remove those cells that, due to random vector integration, display an unwanted stable expression of the auxiliary gene. Here, we develop a traceless selection system that on the one hand allows efficient enrichment of modified cells, and on the other hand can be used to select against cells that retain expression of the auxiliary gene. The value of this system to produce highly enriched-auxiliary gene-free cell products is demonstrated.

Tokamak Physics EXperiment (TPX): Toroidal field magnet design, development and manufacture. SDRL 21, Materials and processes selection. Volume 2

International Nuclear Information System (INIS)

Smith, B.R.

1995-01-01

This document identifies the candidate materials and manufacturing processes selected for development of the TPX Toroidal Field (TF) Magnet. Supporting rationale and selection criteria are provided for justification and the materials properties database report is included for completeness. Specific properties for each material selection are included in this document

Magnetic separation of algae genetically modified for increased intracellular iron uptake

Energy Technology Data Exchange (ETDEWEB)

Buck, Amy [Case Western Reserve University, Cleveland, OH (United States); Cleveland Clinic, Cleveland, OH (United States); Moore, Lee R. [Cleveland Clinic, Cleveland, OH (United States); Lane, Christopher D.; Kumar, Anil; Stroff, Clayton; White, Nicolas [Phycal Inc., Cleveland, OH (United States); Xue, Wei; Chalmers, Jeffrey J. [The Ohio State University, Columbus, OH (United States); Zborowski, Maciej, E-mail: zborowm@ccf.org [Cleveland Clinic, Cleveland, OH (United States)

2015-04-15

Algae were investigated in the past as a potential source of biofuel and other useful chemical derivatives. Magnetic separation of algae by iron oxide nanoparticle binding to cells has been proposed by others for dewatering of cellular mass prior to lipid extraction. We have investigated feasibility of magnetic separation based on the presence of natural iron stores in the cell, such as the ferritin in Auxenochlorella protothecoides (A. protothecoides) strains. The A. protothecoides cell constructs were tested for inserted genes and for increased intracellular iron concentration by inductively coupled plasma atomic absorption (ICP–AA). They were grown in Sueoka’s modified high salt media with added vitamin B1 and increasing concentration of soluble iron compound (FeCl{sub 3} EDTA, from 1× to 8× compared to baseline). The cell magnetic separation conditions were tested using a thin rectangular flow channel pressed against interpolar gaps of a permanent magnet forming a separation system of a well-defined fluid flow and magnetic fringing field geometry (up to 2.2 T and 1000 T/m) dubbed “magnetic deposition microscopy”, or MDM. The presence of magnetic cells in suspension was detected by formation of characteristic deposition bands at the edges of the magnet interpolar gaps, amenable to optical scanning and microscopic examination. The results demonstrated increasing cellular Fe uptake with increasing Fe concentration in the culture media in wild type strain and in selected genetically-modified constructs, leading to magnetic separation without magnetic particle binding. The throughput in this study is not sufficient for an economical scale harvest. - Highlights: • Auxenochlorella protothecoides algae were genetically modified for biofuel production. • Algal iron metabolism was sufficient for their label-less magnetic separation. • High magnetic field and low flow required make the separation scale-up uneconomical.

Magnetic separation of algae genetically modified for increased intracellular iron uptake

International Nuclear Information System (INIS)

Buck, Amy; Moore, Lee R.; Lane, Christopher D.; Kumar, Anil; Stroff, Clayton; White, Nicolas; Xue, Wei; Chalmers, Jeffrey J.; Zborowski, Maciej

2015-01-01

Algae were investigated in the past as a potential source of biofuel and other useful chemical derivatives. Magnetic separation of algae by iron oxide nanoparticle binding to cells has been proposed by others for dewatering of cellular mass prior to lipid extraction. We have investigated feasibility of magnetic separation based on the presence of natural iron stores in the cell, such as the ferritin in Auxenochlorella protothecoides (A. protothecoides) strains. The A. protothecoides cell constructs were tested for inserted genes and for increased intracellular iron concentration by inductively coupled plasma atomic absorption (ICP–AA). They were grown in Sueoka’s modified high salt media with added vitamin B1 and increasing concentration of soluble iron compound (FeCl 3 EDTA, from 1× to 8× compared to baseline). The cell magnetic separation conditions were tested using a thin rectangular flow channel pressed against interpolar gaps of a permanent magnet forming a separation system of a well-defined fluid flow and magnetic fringing field geometry (up to 2.2 T and 1000 T/m) dubbed “magnetic deposition microscopy”, or MDM. The presence of magnetic cells in suspension was detected by formation of characteristic deposition bands at the edges of the magnet interpolar gaps, amenable to optical scanning and microscopic examination. The results demonstrated increasing cellular Fe uptake with increasing Fe concentration in the culture media in wild type strain and in selected genetically-modified constructs, leading to magnetic separation without magnetic particle binding. The throughput in this study is not sufficient for an economical scale harvest. - Highlights: • Auxenochlorella protothecoides algae were genetically modified for biofuel production. • Algal iron metabolism was sufficient for their label-less magnetic separation. • High magnetic field and low flow required make the separation scale-up uneconomical

Pathophysiological aspects of sickle cell vaso-occlusion

International Nuclear Information System (INIS)

Nagel, R.L.

1987-01-01

This book contains over 30 selections. Some of the titles are: An Animal Model for Sickle Cell Vaso-Occlusion: A Study Using NMR and Technetium Imaging; Sickle-Cell Vaso-Occlusion in an Animal Model: Intravital Microscopy and Radionuclide Imaging of Selective Sequestration of Dense Cells; Magnetic Resonance Imaging, Percentage of Dense Cells, and Serum Prostanoids as Tools for Objective Assessment of Pain Crisis: A Preliminary Report; and Painful Crisis and Dense Echinocytes: Effects of Hydration and Vasodilators

A coordination polymer based magnetic adsorbent material for hemoglobin isolation from human whole blood, highly selective and recoverable

Science.gov (United States)

Zhang, Xiaoxing; Tan, Jipeng; Xu, Xinxin; Shi, Fanian; Li, Guanglu; Yang, Yiqiao

2017-09-01

A composite material has been obtained successfully through the loading of nanoscale coordination polymer on magnetic Fe3O4@SiO2 core-shell particle. In this composite material, coordination polymer nanoparticles distribute uniformly on Fe3O4@SiO2 and these two components are "tied" together firmly with chemical bonds. Adsorption experiments suggest this composite material exhibits very excellent selectivity to hemoglobin. But under the same condition, its adsorption to bovine serum albumin can almost be ignored. This selectivity can be attributed to the existence of hydrophobic interactions between coordination polymer nanoparticle and hemoglobin. For composite material, the hemoglobin adsorption process follows Langmuir model perfectly with high speed. The adsorbed hemoglobin can be eluted easily by sodium dodecyl sulfate stripping reagent with structure and biological activity of hemoglobin keeps well. The composite material was also employed to separate hemoglobin from human whole blood, which receives a very satisfactory result. Furthermore, magnetic measurement reveals ferromagnetic character of this composite material with magnetization saturation 3.56 emu g-1 and this guarantees its excellent magnetic separation performance from the treated solution.

Selective Killing of Prostate Tumor Cells by Cytocidal Viruses

National Research Council Canada - National Science Library

Lyles, Douglas

2003-01-01

.... The novelty in our approach is our ability to enhance the selectivity of killing of tumor cells versus normal cells by manipulating the viral genes that control the antiviral interferon response...

Selective Killing of Prostate Tumor Cells by Cytocidal Viruses

National Research Council Canada - National Science Library

Lyles, Douglas

2004-01-01

.... The novelty in our approach is our ability to enhance the selectivity of killing of tumor cells versus normal cells by manipulating the viral genes that control the antiviral interferon response...

Background ELF magnetic fields in incubators: a factor of importance in cell culture work.

Science.gov (United States)

Mild, Kjell Hansson; Wilén, Jonna; Mattsson, Mats-Olof; Simko, Myrtill

2009-07-01

Extremely low frequency (ELF) magnetic fields in cell culture incubators have been measured. Values of the order of tens of muT were found which is in sharp contrast to the values found in our normal environment (0.05-0.1microT). There are numerous examples of biological effects found after exposure to MF at these levels, such as changes in gene expression, blocked cell differentiation, inhibition of the effect of tamoxifen, effects on chick embryo development, etc. We therefore recommend that people working with cell culture incubators check for the background magnetic field and take this into account in performing their experiments, since this could be an unrecognised factor of importance contributing to the variability in the results from work with cell cultures.

Aptamer-based isolation and subsequent imaging of mesenchymal stem cells in ischemic myocard by magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Schaefer, R.; Hermanutz-Klein, U.; Northoff, H. [Universitaetsklinikum Tuebingen (Germany). Inst. fuer Klinische und Experimentelle Transfusionsmedizin; Wiskirchen, J.; Kehlbach, R.; Pintaske, J. [Universitaetsklinikum Tuebingen (Germany). Abt. fuer Radiologische Diagnostik; Guo, K.; Neumann, B.; Voth, V.; Walker, T.; Scheule, A.M.; Greiner, T.O.; Ziemer, G.; Wendel, H.P. [Universitaetsklinikum Tuebingen (Germany). Abt. fuer Thorax-, Herz- und Gefaesschirurgie; Claussen, C.D. [Universitaetsklinikum Tuebingen (Germany). Radiologische Universitaetsklinik

2007-10-15

Purpose: Mesenchymal stem cells (MSC) seem to be a promising cell source for cellular cardiomyoplasty. We recently developed a new aptamer-based specific selection of MSC to provide ''ready to transplant'' cells directly after isolation. We evaluated MRI tracking of newly isolated and freshly transplanted MSC in the heart using one short ex vivo selection step combining specific aptamer-based isolation and labeling of the cells. Materials and Methods: Bone marrow (BM) was collected from healthy pigs. The animals were euthanized and the heart was placed in a perfusion model. During cold ischemia, immunomagnetic isolation of MSC from the BM by MSC-specific aptamers labeled with Dynabeads {sup registered} was performed within 2 h. For histological identification the cells were additionally stained with PKH26. Approx. 3 x 10{sup 6} of the freshly aptamer-isolated cells were injected into the ramus interventricularis anterior (RIVA) and 5 x 10{sup 5} cells were injected directly into myocardial tissue after damaging the respective area by freezing (cryo-scar). 3 x 10{sup 6} of the aptamer-isolated cells were kept for further characterization (FACS and differentiation assays). 20 h after cell transplantation, MRI of the heart using a clinical 3.0 Tesla whole body scanner (Magnetom Trio, Siemens, Germany) was performed followed by histological examinations. Results: The average yield of sorted cells from 120 ml BM was 7 x 10{sup 6} cells. The cells were cultured and showed MSC-like properties. MRI showed reproducible artifacts within the RIVA-perfusion area and the cryo-scar with surprisingly excellent quality. The histological examination of the biopsies showed PKH26-positive cells within the areas which were positive in the MRI in contrast to the control biopsies. Conclusion: Immunomagnetic separation of MSC by specific aptamers linked to magnetic particles is feasible, effective and combines a specific separation and labeling technique to a &apos

Actively-targeted LTVSPWY peptide-modified magnetic nanoparticles for tumor imaging

Directory of Open Access Journals (Sweden)

Jie L-Y

2012-07-01

Full Text Available Li-Yong Jie,1 Li-Li Cai,2 Le-Jian Wang,2 Xiao-Ying Ying,2 Ri-Sheng Yu,1 Min-Ming Zhang,1 Yong-Zhong Du21Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 2College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, People's Republic of ChinaBackground: Magnetic resonance imaging (MRI is widely used in modern clinical medicine as a diagnostic tool, and provides noninvasive and three-dimensional visualization of biological phenomena in living organisms with high spatial and temporal resolution. Therefore, considerable attention has been paid to magnetic nanoparticles as MRI contrast agents with efficient targeting ability and cellular internalization ability, which make it possible to offer higher contrast and information-rich images for detection of disease.Methods: LTVSPWY peptide-modified PEGylated chitosan (LTVSPWY-PEG-CS was synthesized by chemical reaction, and the chemical structure was confirmed by 1H-NMR. LTVSPWY-PEG-CS-modified magnetic nanoparticles were prepared successfully using the solvent diffusion method. Their particle size, size distribution, and zeta potential were measured by dynamic light scattering and electrophoretic mobility, and their surface morphology was investigated by transmission electron microscopy. To investigate their selective targeting ability, the cellular uptake of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was observed in a cocultured system of SKOV-3 cells which overexpress HER2 and A549 cells which are HER2-negative. The in vitro cytotoxicity of these nanoparticles in SKOV-3 and A549 cells was measured using the MTT method. The SKOV-3-bearing nude mouse model was used to investigate the tumor targeting ability of the magnetic nanoparticles in vivo.Results: The average diameter and zeta potential of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was 267.3 ± 23.4 nm and 30.5 ± 7.0 mV, respectively, with a narrow size distribution and

Functionalized magnetic nanowires for chemical and magneto-mechanical induction of cancer cell death

KAUST Repository

Martinez Banderas, Aldo; Aires, Antonio; Teran, Francisco J.; Perez, Jose E.; Cadenas, Jael F.; Alsharif, Nouf; Ravasi, Timothy; Cortajarena, Aitziber L.; Kosel, Jü rgen

2016-01-01

Exploiting and combining different properties of nanomaterials is considered a potential route for next generation cancer therapies. Magnetic nanowires (NWs) have shown good biocompatibility and a high level of cellular internalization. We induced cancer cell death by combining the chemotherapeutic effect of doxorubicin (DOX)-functionalized iron NWs with the mechanical disturbance under a low frequency alternating magnetic field. (3-aminopropyl)triethoxysilane (APTES) and bovine serum albumin (BSA) were separately used for coating NWs allowing further functionalization with DOX. Internalization was assessed for both formulations by confocal reflection microscopy and inductively coupled plasma-mass spectrometry. From confocal analysis, BSA formulations demonstrated higher internalization and less agglomeration. The functionalized NWs generated a comparable cytotoxic effect in breast cancer cells in a DOX concentration-dependent manner, (~60% at the highest concentration tested) that was significantly different from the effect produced by free DOX and non-functionalized NWs formulations. A synergistic cytotoxic effect is obtained when a magnetic field (1 mT, 10 Hz) is applied to cells treated with DOX-functionalized BSA or APTES-coated NWs, (~70% at the highest concentration). In summary, a bimodal method for cancer cell destruction was developed by the conjugation of the magneto-mechanical properties of iron NWs with the effect of DOX producing better results than the individual effects.

Functionalized magnetic nanowires for chemical and magneto-mechanical induction of cancer cell death

KAUST Repository

Martinez Banderas, Aldo Isaac

2016-10-24

Exploiting and combining different properties of nanomaterials is considered a potential route for next generation cancer therapies. Magnetic nanowires (NWs) have shown good biocompatibility and a high level of cellular internalization. We induced cancer cell death by combining the chemotherapeutic effect of doxorubicin (DOX)-functionalized iron NWs with the mechanical disturbance under a low frequency alternating magnetic field. (3-aminopropyl)triethoxysilane (APTES) and bovine serum albumin (BSA) were separately used for coating NWs allowing further functionalization with DOX. Internalization was assessed for both formulations by confocal reflection microscopy and inductively coupled plasma-mass spectrometry. From confocal analysis, BSA formulations demonstrated higher internalization and less agglomeration. The functionalized NWs generated a comparable cytotoxic effect in breast cancer cells in a DOX concentration-dependent manner, (~60% at the highest concentration tested) that was significantly different from the effect produced by free DOX and non-functionalized NWs formulations. A synergistic cytotoxic effect is obtained when a magnetic field (1 mT, 10 Hz) is applied to cells treated with DOX-functionalized BSA or APTES-coated NWs, (~70% at the highest concentration). In summary, a bimodal method for cancer cell destruction was developed by the conjugation of the magneto-mechanical properties of iron NWs with the effect of DOX producing better results than the individual effects.

Functionalized magnetic nanowires for chemical and magneto-mechanical induction of cancer cell death.

Science.gov (United States)

Martínez-Banderas, Aldo Isaac; Aires, Antonio; Teran, Francisco J; Perez, Jose Efrain; Cadenas, Jael F; Alsharif, Nouf; Ravasi, Timothy; Cortajarena, Aitziber L; Kosel, Jürgen

2016-10-24

Exploiting and combining different properties of nanomaterials is considered a potential route for next generation cancer therapies. Magnetic nanowires (NWs) have shown good biocompatibility and a high level of cellular internalization. We induced cancer cell death by combining the chemotherapeutic effect of doxorubicin (DOX)-functionalized iron NWs with the mechanical disturbance under a low frequency alternating magnetic field. (3-aminopropyl)triethoxysilane (APTES) and bovine serum albumin (BSA) were separately used for coating NWs allowing further functionalization with DOX. Internalization was assessed for both formulations by confocal reflection microscopy and inductively coupled plasma-mass spectrometry. From confocal analysis, BSA formulations demonstrated higher internalization and less agglomeration. The functionalized NWs generated a comparable cytotoxic effect in breast cancer cells in a DOX concentration-dependent manner, (~60% at the highest concentration tested) that was significantly different from the effect produced by free DOX and non-functionalized NWs formulations. A synergistic cytotoxic effect is obtained when a magnetic field (1 mT, 10 Hz) is applied to cells treated with DOX-functionalized BSA or APTES-coated NWs, (~70% at the highest concentration). In summary, a bimodal method for cancer cell destruction was developed by the conjugation of the magneto-mechanical properties of iron NWs with the effect of DOX producing better results than the individual effects.

Selective Killing of Prostate Tumor Cells by Cytocidal Viruses

National Research Council Canada - National Science Library

Lyles, Douglas S

2005-01-01

...). The novelty in our approach is our ability to enhance the selectivity of VSV-induced killing of tumor cells versus normal cells by manipulating the viral genes that control the antiviral interferon response...

A hybrid magnetic/complementary metal oxide semiconductor three-context memory bit cell for non-volatile circuit design

International Nuclear Information System (INIS)

Jovanović, B.; Brum, R. M.; Torres, L.

2014-01-01

After decades of continued scaling to the beat of Moore's law, it now appears that conventional silicon based devices are approaching their physical limits. In today's deep-submicron nodes, a number of short-channel and quantum effects are emerging that affect the manufacturing process, as well as, the functionality of the microelectronic systems-on-chip. Spintronics devices that exploit both the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, are promising solutions to circumvent these scaling threats. Being compatible with the CMOS technology, such devices offer a promising synergy of radiation immunity, infinite endurance, non-volatility, increased density, etc. In this paper, we present a hybrid (magnetic/CMOS) cell that is able to store and process data both electrically and magnetically. The cell is based on perpendicular spin-transfer torque magnetic tunnel junctions (STT-MTJs) and is suitable for use in magnetic random access memories and reprogrammable computing (non-volatile registers, processor cache memories, magnetic field-programmable gate arrays, etc). To demonstrate the potential our hybrid cell, we physically implemented a small hybrid memory block using 45 nm × 45 nm round MTJs for the magnetic part and 28 nm fully depleted silicon on insulator (FD-SOI) technology for the CMOS part. We also report the cells measured performances in terms of area, robustness, read/write speed and energy consumption

A hybrid magnetic/complementary metal oxide semiconductor three-context memory bit cell for non-volatile circuit design

Energy Technology Data Exchange (ETDEWEB)

Jovanović, B., E-mail: bojan.jovanovic@lirmm.fr, E-mail: lionel.torres@lirmm.fr; Brum, R. M.; Torres, L. [LIRMM—University of Montpellier 2/UMR CNRS 5506, 161 Rue Ada, 34095 Montpellier (France)

2014-04-07

After decades of continued scaling to the beat of Moore's law, it now appears that conventional silicon based devices are approaching their physical limits. In today's deep-submicron nodes, a number of short-channel and quantum effects are emerging that affect the manufacturing process, as well as, the functionality of the microelectronic systems-on-chip. Spintronics devices that exploit both the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, are promising solutions to circumvent these scaling threats. Being compatible with the CMOS technology, such devices offer a promising synergy of radiation immunity, infinite endurance, non-volatility, increased density, etc. In this paper, we present a hybrid (magnetic/CMOS) cell that is able to store and process data both electrically and magnetically. The cell is based on perpendicular spin-transfer torque magnetic tunnel junctions (STT-MTJs) and is suitable for use in magnetic random access memories and reprogrammable computing (non-volatile registers, processor cache memories, magnetic field-programmable gate arrays, etc). To demonstrate the potential our hybrid cell, we physically implemented a small hybrid memory block using 45 nm × 45 nm round MTJs for the magnetic part and 28 nm fully depleted silicon on insulator (FD-SOI) technology for the CMOS part. We also report the cells measured performances in terms of area, robustness, read/write speed and energy consumption.

Influence on bionomics of endothelial progenitor cells labeling with magnetic nanoparticles

International Nuclear Information System (INIS)

Mai Xiaoli; Teng Gaojun; Ma Zhanlong; Sun Junhui; Zhang Yu; Gu Ning

2008-01-01

Objective: To explore the influence of home synthesize magnetic iron oxide (called Fe 2 O 3 -PLL) labeling on peripheral blood endothelial progenitor cells (EPCs) bionomics to provide experimental foundation for MR imaging ex and in vivo. Methods: Fe 2 O 3 was incubated with PLL for 2 hours to obtain a complex of Fe 2 O 3 -PLL. Rabbit peripheral blood mononuclear cells were isolated and EPCs were selected by adherence method. Fe 2 O 3 -PLL was used to label EPCs. Prussian blue stain and electron microscope was used for showing intracellular iron. MTF assay was assessed to evaluate the difference of growth curve between unlabeled and labeled with 25 mg/L Fe 2 O 3 -PLL. Flow cytometry was performed to analyze cell cycle, cell apoptosis and the expression of surface markers of labeled and unlabeled cells. Expressions of eNOS, KDR and vWF at mRNA levels among unlabeled and labeled EPCs were detected by real-time polymerase chain reaction. Calcium ion channel and membrane fluidity were observed and analyzed by laser confocal microscopy. Statistical analyses were used with ANOVA and t test. Results: Almost 100% cells were labeled by Fe 2 O 3 -PLL, iron-containing vesicles were intracytoplasma. There was no statistical difference in cells growth curve, cell life cycle [(93.74±3.52)%, (94.57±3.66)%] and cell apoptosis rate (12.89±1.81)%, (11.67±1.18)%) between labeling with Fe 2 O 3 -PLL at a concentration of 25 mg/L and unlabeled cells (t=0.283, P>0.05; t=0.977, P>0.05). There was also no statistical difference in relative amount of eNOS, KDR and vWF at mRNA levels and the expression of surface phenotypic markers (CD34, CD106, CD146 and KDR) between two groups (P>0.05). In addition, Labeling had little influence on calcium ion channel and didn't significantly alter cell membrane fluidity. Conclusions: The rabbit peripheral blood EPCs can be effective labeled with Fe 2 O 3 -PLL and without significant influence on cells bionomics at a low concentration of 25 mg

Magnetic microfluidic platform for biomedical applications using magnetic nanoparticles

KAUST Repository

Stipsitz, Martin

2015-05-01

Microfluidic platforms are well-suited for biomedical analysis and usually consist of a set of units which guarantee the manipulation, detection and recognition of bioanalyte in a reliable and flexible manner. Additionally, the use of magnetic fields for perfoming the aforementioned tasks has been steadily gainining interest. This is due to the fact that magnetic fields can be well tuned and applied either externally or from a directly integrated solution in the diagnostic system. In combination with these applied magnetic fields, magnetic nanoparticles are used. In this paper, we present some of our most recent results in research towards a) microfluidic diagnostics using MR sensors and magnetic particles and b) single cell analysis using magnetic particles. We have successfully manipulated magnetically labeled bacteria and measured their response with integrated GMR sensors and we have also managed to separate magnetically labeled jurkat cells for single cell analysis. © 2015 Trans Tech Publications, Switzerland.

Magnetic microfluidic platform for biomedical applications using magnetic nanoparticles

KAUST Repository

Stipsitz, Martin; Kokkinis, Georgios; Gooneratne, Chinthaka Pasan; Kosel, Jü rgen; Cardoso, Susana; Cardoso, Filipe; Giouroudi, Ioanna

2015-01-01

Microfluidic platforms are well-suited for biomedical analysis and usually consist of a set of units which guarantee the manipulation, detection and recognition of bioanalyte in a reliable and flexible manner. Additionally, the use of magnetic fields for perfoming the aforementioned tasks has been steadily gainining interest. This is due to the fact that magnetic fields can be well tuned and applied either externally or from a directly integrated solution in the diagnostic system. In combination with these applied magnetic fields, magnetic nanoparticles are used. In this paper, we present some of our most recent results in research towards a) microfluidic diagnostics using MR sensors and magnetic particles and b) single cell analysis using magnetic particles. We have successfully manipulated magnetically labeled bacteria and measured their response with integrated GMR sensors and we have also managed to separate magnetically labeled jurkat cells for single cell analysis. © 2015 Trans Tech Publications, Switzerland.

How a high-gradient magnetic field could affect cell life

Czech Academy of Sciences Publication Activity Database

Zablotskyy, Vitaliy A.; Polyakova, Tetyana; Lunov, Oleg; Dejneka, Alexandr

2016-01-01

Roč. 6, Nov (2016), 1-12, č. článku 37407. ISSN 2045-2322 Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : high-gradient magnetic field * cell Subject RIV: BO - Biophysics Impact factor: 4.259, year: 2016

Breast cancer cells synchronous labeling and separation based on aptamer and fluorescence-magnetic silica nanoparticles

Science.gov (United States)

Wang, Qiu-Yue; Huang, Wei; Jiang, Xing-Lin; Kang, Yan-Jun

2018-01-01

In this work, an efficient method based on biotin-labeled aptamer and streptavidin-conjugated fluorescence-magnetic silica nanoprobes (FITC@Fe3O4@SiNPs-SA) has been established for human breast carcinoma MCF-7 cells synchronous labeling and separation. Carboxyl-modified fluorescence-magnetic silica nanoparticles (FITC@Fe3O4@SiNPs-COOH) were first synthesized using the Stöber method. Streptavidin (SA) was then conjugated to the surface of FITC@Fe3O4@SiNPs-COOH. The MCF-7 cell suspension was incubated with biotin-labeled MUC-1 aptamer. After centrifugation and washing, the cells were then treated with FITC@Fe3O4@SiNPs-SA. Afterwards, the mixtures were separated by a magnet. The cell-probe conjugates were then imaged using fluorescent microscopy. The results show that the MUC-1 aptamer could recognize and bind to the targeted cells with high affinity and specificity, indicating the prepared FITC@Fe3O4@SiNPs-SA with great photostability and superparamagnetism could be applied effectively in labeling and separation for MCF-7 cell in suspension synchronously. In addition, the feasibility of MCF-7 cells detection in peripheral blood was assessed. The results indicate that the method above is also applicable for cancer cells synchronous labeling and separation in complex biological system.

Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

International Nuclear Information System (INIS)

Xia, Hui; Tong, Ruijie; Song, Yanling; Xiong, Fang; Li, Jiman; Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei; Wu, Jiang

2017-01-01

Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

Science.gov (United States)

Xia, Hui; Tong, Ruijie; Song, Yanling; Xiong, Fang; Li, Jiman; Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei; Wu, Jiang

2017-04-01

Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Xia, Hui; Tong, Ruijie [Sichuan University, West China Medical Center (China); Song, Yanling [Shenyang University of Chemical Technology, College of Pharmaceutical and Biological Engineering (China); Xiong, Fang [Sichuan University, West China College of Stomatology (China); Li, Jiman [Sichuan Cancer Hospital, Pathology Department (China); Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei, E-mail: zzw2002400@126.com; Wu, Jiang, E-mail: jw@scu.edu.cn [Sichuan University, West China Medical Center (China)

2017-04-15

Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture.

Science.gov (United States)

Klein, M; Pankiewicz, R; Zalas, M; Stampor, W

2016-07-21

The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism.

Selective tumor cell targeting by the disaccharide moiety of bleomycin.

Science.gov (United States)

Yu, Zhiqiang; Schmaltz, Ryan M; Bozeman, Trevor C; Paul, Rakesh; Rishel, Michael J; Tsosie, Krystal S; Hecht, Sidney M

2013-02-27

In a recent study, the well-documented tumor targeting properties of the antitumor agent bleomycin (BLM) were studied in cell culture using microbubbles that had been derivatized with multiple copies of BLM. It was shown that BLM selectively targeted MCF-7 human breast carcinoma cells but not the "normal" breast cell line MCF-10A. Furthermore, it was found that the BLM analogue deglycobleomycin, which lacks the disaccharide moiety of BLM, did not target either cell line, indicating that the BLM disaccharide moiety is necessary for tumor selectivity. Not resolved in the earlier study were the issues of whether the BLM disaccharide moiety alone is sufficient for tumor cell targeting and the possible cellular uptake of the disaccharide. In the present study, we conjugated BLM, deglycoBLM, and BLM disaccharide to the cyanine dye Cy5**. It was found that the BLM and BLM disaccharide conjugates, but not the deglycoBLM conjugate, bound selectively to MCF-7 cells and were internalized. The same was also true for the prostate cancer cell line DU-145 (but not for normal PZ-HPV-7 prostate cells) and for the pancreatic cancer cell line BxPC-3 (but not for normal SVR A221a pancreas cells). The targeting efficiency of the disaccharide was only slightly less than that of BLM in MCF-7 and DU-145 cells and comparable to that of BLM in BxPC-3 cells. These results establish that the BLM disaccharide is both necessary and sufficient for tumor cell targeting, a finding with obvious implications for the design of novel tumor imaging and therapeutic agents.

Cell-selective metabolic labeling of biomolecules with bioorthogonal functionalities.

Science.gov (United States)

Xie, Ran; Hong, Senlian; Chen, Xing

2013-10-01

Metabolic labeling of biomolecules with bioorthogonal functionalities enables visualization, enrichment, and analysis of the biomolecules of interest in their physiological environments. This versatile strategy has found utility in probing various classes of biomolecules in a broad range of biological processes. On the other hand, metabolic labeling is nonselective with respect to cell type, which imposes limitations for studies performed in complex biological systems. Herein, we review the recent methodological developments aiming to endow metabolic labeling strategies with cell-type selectivity. The cell-selective metabolic labeling strategies have emerged from protein and glycan labeling. We envision that these strategies can be readily extended to labeling of other classes of biomolecules. Copyright © 2013 Elsevier Ltd. All rights reserved.

Repair of Ischemic Injury by Pluripotent Stem Cell Based Cell Therapy without Teratoma through Selective Photosensitivity

Directory of Open Access Journals (Sweden)

Seung-Ju Cho

2015-12-01

Full Text Available Stem-toxic small molecules have been developed to induce selective cell death of pluripotent stem cells (PSCs to lower the risk of teratoma formation. However, despite their high efficacies, chemical-based approaches may carry unexpected toxicities on specific differentiated cell types. Herein, we took advantage of KillerRed (KR as a suicide gene, to selectively induce phototoxicity using visible light via the production of reactive oxygen species. PSCs in an undifferentiated state that exclusively expressed KR (KR-PSCs were eliminated by a single exposure to visible light. This highly selective cell death in KR-PSCs was exploited to successfully inhibit teratoma formation. In particular, endothelial cells from KR-mPSCs remained fully functional in vitro and sufficient to repair ischemic injury in vivo regardless of light exposure, suggesting that a genetic approach in which KR is expressed in a tightly controlled manner would be a viable strategy to inhibit teratoma formation for future safe PSC-based therapies.

Pulsed magnetic field enhances therapeutic efficiency of mesenchymal stem cells in chronic neuropathic pain model.

Science.gov (United States)

Mert, Tufan; Kurt, Akif Hakan; Altun, İdiris; Celik, Ahmet; Baran, Furkan; Gunay, Ismail

2017-05-01

Cell-based or magnetic field therapies as alternative approaches to pain management have been tested in several experimental pain models. The aim of this study therefore was to investigate the actions of the cell-based therapy (adipose tissue derived mesenchymal stem cells; ADMSC) or pulsed magnetic field (PMF) therapy and magneto-cell therapy (combination of ADMSC and PMF) in chronic constriction nerve injury model (CCI). The actions of individual ADMSC (route dependent [systemic or local], time-dependent [a day or a week after surgery]), or PMF and their combination (magneto-cell) therapies on hyperalgesia and allodynia were investigated by using thermal plantar test and a dynamic plantar aesthesiometer, respectively. In addition, various cytokine levels (IL-1β, IL-6, and IL-10) of rat sciatic nerve after CCI were analyzed. Following the CCI, both latency and threshold significantly decreased. ADMSC or PMF significantly increased latencies and thresholds. The combination of ADMSC with PMF even more significantly increased latency and threshold when compared with ADMSC alone. However, ADMSC-induced decrease in pro-inflammatory or increase in anti-inflammatory cytokines levels were partially prevented by PMF treatments. Present findings may suggest that both cell-based and magnetic therapies can effectively attenuate chronic neuropathic pain symptoms. Combined magneto-cell therapy may also efficiently reverse neuropathic signs. Bioelectromagnetics. 38:255-264, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

IL-15 inhibits pre-B cell proliferation by selectively expanding Mac-1+B220+ NK cells

International Nuclear Information System (INIS)

Nakajima, Shinsuke; Hida, Shigeaki; Taki, Shinsuke

2008-01-01

Natural killer (NK) cells are the cells critical for inhibition of repopulation of allogenic bone marrow cells. However, it is not well known if NK cells affect autologous lymphopoiesis. Here, we observed that NK cells could inhibit pre-B cell proliferation in vitro driven by interleukin (IL)-7 in a manner dependent on IL-15. Interestingly, the great majority of expanding NK cells were Mac-1 + B220 + , a recently identified potent interferon (IFN)-γ producer. Indeed, IFN-γ was produced in those cultures, and pre-B cells lacking IFN-γ receptors, but not those lacking type I IFN receptors, were resistant to such an inhibition. Furthermore, even NK cells from mice lacking β2-microglobulin, which were known to be functionally dampened, inhibited pre-B cell proliferation as well. Thus, activated NK cells, which were expanded selectively by IL-15, could potentially regulate B lymphopoiesis through IFN-γ beyond the selection imposed upon self-recognition

Laser Process for Selective Emitter Silicon Solar Cells

Directory of Open Access Journals (Sweden)

G. Poulain

2012-01-01

Full Text Available Selective emitter solar cells can provide a significant increase in conversion efficiency. However current approaches need many technological steps and alignment procedures. This paper reports on a preliminary attempt to reduce the number of processing steps and therefore the cost of selective emitter cells. In the developed procedure, a phosphorous glass covered with silicon nitride acts as the doping source. A laser is used to open locally the antireflection coating and at the same time achieve local phosphorus diffusion. In this process the standard chemical etching of the phosphorous glass is avoided. Sheet resistance variation from 100 Ω/sq to 40 Ω/sq is demonstrated with a nanosecond UV laser. Numerical simulation of the laser-matter interaction is discussed to understand the dopant diffusion efficiency. Preliminary solar cells results show a 0.5% improvement compared with a homogeneous emitter structure.

Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

International Nuclear Information System (INIS)

Perrier, Marine; Gary-Bobo, Magali; Lartigue, Lenaïc; Brevet, David; Morère, Alain; Garcia, Marcel; Maillard, Philippe; Raehm, Laurence; Guari, Yannick; Larionova, Joulia; Durand, Jean-Olivier; Mongin, Olivier; Blanchard-Desce, Mireille

2013-01-01

An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

Energy Technology Data Exchange (ETDEWEB)

Perrier, Marine [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Gary-Bobo, Magali [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Lartigue, Lenaiec; Brevet, David [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Morere, Alain; Garcia, Marcel [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Maillard, Philippe [Universite Paris-Sud, UMR 176 CNRS, Institut Curie (France); Raehm, Laurence; Guari, Yannick, E-mail: yannick.guari@um2.fr; Larionova, Joulia; Durand, Jean-Olivier, E-mail: durand@univ-montp2.fr [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Mongin, Olivier [Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, CNRS UMR 6226 (France); Blanchard-Desce, Mireille [Universite Bordeaux, Institut des Sciences Moleculaires, UMR CNRS 5255 (France)

2013-05-15

An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

Cancer cell-selective, clathrin-mediated endocytosis of aptamer decorated nanoparticles

Science.gov (United States)

Engelberg, Shira; Modrejewski, Julia; Walter, Johanna G.; Livney, Yoav D.; Assaraf, Yehuda G.

2018-01-01

Lung cancer is the leading cause of cancer mortality worldwide, resulting in 88% deaths of all diagnosed patients. Hence, novel therapeutic modalities are urgently needed. Single-stranded oligonucleotide-based aptamers (APTs) are excellent ligands for tumor cell targeting. However, the molecular mechanisms underlying their internalization into living cells have been poorly studied. Towards the application of APTs for active drug targeting to cancer cells, we herein studied the mechanism underlying S15-APT internalization into human non-small cell lung cancer A549 cells. We thus delineated the mode of entry of a model nanomedical system based on quantum dots (QDs) decorated with S15-APTs as a selective targeting moiety for uptake by A549 cells. These APT-decorated QDs displayed selective binding to, and internalization by target A549 cells, but not by normal human bronchial epithelial BEAS2B, cervical carcinoma (HeLa) and colon adenocarcinoma CaCo-2 cells, hence demonstrating high specificity. Flow cytometric analysis revealed a remarkably low dissociation constant of S15-APTs-decorated QDs to A549 cells (Kd = 13.1 ± 1.6 nM). Through the systematic application of a series of established inhibitors of known mechanisms of endocytosis, we show that the uptake of S15-APTs proceeds via a classical clathrin-dependent receptor-mediated endocytosis. This cancer cell-selective mode of entry could possibly be used in the future to evade plasma membrane-localized multidrug resistance efflux pumps, thereby overcoming an important mechanism of cancer multidrug resistance. PMID:29765515

Stabilization of temperature during magnetic hyperthermia by Ce substituted magnetite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Shaw, S.K.; Alla, S.K. [Department of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mandal, R.K. [Department of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Prasad, N.K., E-mail: nandkp.met@iitbhu.ac.in [Department of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

2017-07-15

Highlights: • Ce{sub x}Fe{sub 3−x}O{sub 4} (0.01 ≤ x ≤ 0.5) nanoparticles below 15 nm were synthesized by microwave refluxing method. • The saturation magnetization decreased with increased Ce concentration. • The sample displayed stabilization of temperature near 42 °C during magnetic hyperthermia. - Abstract: We report here magnetic hyperthermia using nanoparticles of Ce{sub x}Fe{sub 3−x}O{sub 4} (x = 0.01, 0.05, 0.1, 0.3 and 0.5) during which temperature was found to be stabilizing near 42 °C. This happens despite of their high saturation magnetization (M{sub S}) and Curie temperature (T{sub C}) values. It was observed that by selecting an appropriate magnetic field the temperature can be rose exactly near the therapeutic temperature and thus it will help to selectively kill the cancerous cells leaving normal cells unaffected. These nanoparticles (size around 8–15 nm) were produced by single step microwave refluxing technique. X-ray diffraction (XRD) analysis demonstrates that samples were essentially single phase except for x = 0.5 sample. The X-ray photoelectron spectroscopy (XPS) study for the samples demonstrated that Ce was present in both Ce{sup 3+} and Ce{sup 4+} states. The saturation magnetization value of the samples decreased sharply from 62 Am{sup 2}/kg for x = 0.01 to 19 Am{sup 2}/kg for x = 0.1. This value further decreased with increased Ce doping.

IS MAGNETIC RECONNECTION THE CAUSE OF SUPERSONIC UPFLOWS IN GRANULAR CELLS?

Energy Technology Data Exchange (ETDEWEB)

Borrero, J. M.; Schmidt, W. [Kiepenheuer-Institut fuer Sonnenphysik, Schoeneckstr. 6, D-79110, Freiburg (Germany); Martinez Pillet, V.; Quintero Noda, C.; Bonet, J. A. [Instituto de Astrofisica de Canarias, Avd. Via Lactea s/n, E-38200 La Laguna (Spain); Del Toro Iniesta, J. C.; Bellot Rubio, L. R., E-mail: borrero@kis.uni-freiburg.de, E-mail: wolfgang@kis.uni-freiburg.de, E-mail: vmp@ll.iac.es, E-mail: cqn@ll.iac.es, E-mail: jab@ll.iac.es, E-mail: jti@iaa.es, E-mail: lbellot@iaa.es [Instituto de Astrofisica de Andalucia (CSIC), Apdo. de Correos 3004, E-18080 Granada (Spain)

2013-05-01

In a previous work, we reported on the discovery of supersonic magnetic upflows on granular cells in data from the SUNRISE/IMaX instrument. In the present work, we investigate the physical origin of these events employing data from the same instrument but with higher spectral sampling. By means of the inversion of Stokes profiles we are able to recover the physical parameters (temperature, magnetic field, line-of-sight velocity, etc.) present in the solar photosphere at the time of these events. The inversion is performed in a Monte-Carlo-like fashion, that is, repeating it many times with different initializations and retaining only the best result. We find that many of the events are characterized by a reversal in the polarity of the magnetic field along the vertical direction in the photosphere, accompanied by an enhancement in the temperature and by supersonic line-of-sight velocities. In about half of the studied events, large blueshifted and redshifted line-of-sight velocities coexist above/below each other. These features can be explained in terms of magnetic reconnection, where the energy stored in the magnetic field is released in the form of kinetic and thermal energy when magnetic field lines of opposite polarities coalesce. However, the agreement with magnetic reconnection is not perfect and, therefore, other possible physical mechanisms might also play a role.

Direct observation of enhanced magnetism in individual size- and shape-selected 3 d transition metal nanoparticles

Science.gov (United States)

Kleibert, Armin; Balan, Ana; Yanes, Rocio; Derlet, Peter M.; Vaz, C. A. F.; Timm, Martin; Fraile Rodríguez, Arantxa; Béché, Armand; Verbeeck, Jo; Dhaka, R. S.; Radovic, Milan; Nowak, Ulrich; Nolting, Frithjof

2017-05-01

Magnetic nanoparticles are critical building blocks for future technologies ranging from nanomedicine to spintronics. Many related applications require nanoparticles with tailored magnetic properties. However, despite significant efforts undertaken towards this goal, a broad and poorly understood dispersion of magnetic properties is reported, even within monodisperse samples of the canonical ferromagnetic 3 d transition metals. We address this issue by investigating the magnetism of a large number of size- and shape-selected, individual nanoparticles of Fe, Co, and Ni using a unique set of complementary characterization techniques. At room temperature, only superparamagnetic behavior is observed in our experiments for all Ni nanoparticles within the investigated sizes, which range from 8 to 20 nm. However, Fe and Co nanoparticles can exist in two distinct magnetic states at any size in this range: (i) a superparamagnetic state, as expected from the bulk and surface anisotropies known for the respective materials and as observed for Ni, and (ii) a state with unexpected stable magnetization at room temperature. This striking state is assigned to significant modifications of the magnetic properties arising from metastable lattice defects in the core of the nanoparticles, as concluded by calculations and atomic structural characterization. Also related with the structural defects, we find that the magnetic state of Fe and Co nanoparticles can be tuned by thermal treatment enabling one to tailor their magnetic properties for applications. This paper demonstrates the importance of complementary single particle investigations for a better understanding of nanoparticle magnetism and for full exploration of their potential for applications.

Beyond Helper Phage: Using "Helper Cells" to Select Peptide Affinity Ligands.

Directory of Open Access Journals (Sweden)

M Lisa Phipps

Full Text Available Peptides are important affinity ligands for microscopy, biosensing, and targeted delivery. However, because they can have low affinity for their targets, their selection from large naïve libraries can be challenging. When selecting peptidic ligands from display libraries, it is important to: 1 ensure efficient display; 2 maximize the ability to select high affinity ligands; and 3 minimize the effect of the display context on binding. The "helper cell" packaging system has been described as a tool to produce filamentous phage particles based on phagemid constructs with varying display levels, while remaining free of helper phage contamination. Here we report on the first use of this system for peptide display, including the systematic characterization and optimization of helper cells, their inefficient use in antibody display and their use in creating and selecting from a set of phage display peptide libraries. Our libraries were analyzed with unprecedented precision by standard or deep sequencing, and shown to be superior in quality than commercial gold standards. Using our helper cell libraries, we have obtained ligands recognizing Yersinia pestis surface antigen F1V and L-glutamine-binding periplasmic protein QBP. In the latter case, unlike any of the peptide library selections described so far, we used a combination of phage and yeast display to select intriguing peptide ligands. Based on the success of our selections we believe that peptide libraries obtained with helper cells are not only suitable, but preferable to traditional phage display libraries for selection of peptidic ligands.

Model of inter-cell interference phenomenon in 10 nm magnetic tunnel junction with perpendicular anisotropy array due to oscillatory stray field from neighboring cells

Science.gov (United States)

Ohuchida, Satoshi; Endoh, Tetsuo

2018-06-01

In this paper, we propose a new model of inter-cell interference phenomenon in a 10 nm magnetic tunnel junction with perpendicular anisotropy (p-MTJ) array and investigated the interference effect between a program cell and unselected cells due to the oscillatory stray field from neighboring cells by Landau–Lifshitz–Gilbert micromagnetic simulation. We found that interference brings about a switching delay in a program cell and excitation of magnetization precession in unselected cells even when no programing current passes through. The origin of interference is ferromagnetic resonance between neighboring cells. During the interference period, the precession frequency of the program cell is 20.8 GHz, which synchronizes with that of the theoretical precession frequency f = γH eff in unselected cells. The disturbance strength of unselected cells decreased to be inversely proportional to the cube of the distance from the program cell, which is in good agreement with the dependence of stray field on the distance from the program cell calculated by the dipole approximation method.

Effect of magnetic nanoparticles on apoptosis and cell cycle induced by wogonin in Raji cells

Directory of Open Access Journals (Sweden)

Wang XM

2012-02-01

Full Text Available Lei Wang1,2,*, Haijun Zhang1,2,*, Baoan Chen1,2, Guohua Xia1,2, Shuai Wang1,2, Jian Cheng1,2, Zeye Shao1,2, Chong Gao1,2, Wen Bao1,2, Liang Tian1,2, Yanyan Ren1,2, Peipei Xu1,2, Xiaohui Cai1,2, Ran Liu1,2, Xuemei Wang3 1Department of Hematology and Oncology, Zhongda Hospital, Medical School, 2Faculty of Oncology, Medical School, 3State Key Laboratory of Bioelectronics (Chien-Shiung Wu Laboratory, Southeast University, Nanjing, China*These authors contributed equally to this workAbstract: Traditional Chinese medicine is gradually becoming a new source of anticancer drugs. One such example is wogonin, which is cytotoxic to various cancer cell lines in vitro. However, due to its low water solubility, wogonin is restricted to clinical administration. Recently, the application of drug-coated magnetic nanoparticles (MNPs to increase water solubility of the drug and to enhance its chemotherapeutic efficiency has attracted much attention. In this study, wogonin was conjugated with the drug delivery system of MNPs by mechanical absorption polymerization to fabricate wogonin-loaded MNPs. It was demonstrated that MNPs could strengthen wogonin-induced cell inhibition, apoptosis, and cell cycle arrest in Raji cells by methylthiazol tetrazolium assay, flow cytometer assay, and nuclear 4',6-diamidino-2-phenylindole staining. Furthermore, the molecular mechanisms of these phenomena were explored by western blot, in which the protein levels of caspase 8 and caspase 3 were increased significantly while those of survivin and cyclin E were decreased significantly in wogonin-MNPs group. These findings suggest that the combination of wogonin and MNPs provides a promising strategy for lymphoma therapy.Keywords: wogonin, magnetic nanoparticles, Raji cell, apoptosis, cell cycle, caspase 8, caspase 3, survivin, cyclin E

Impact of interplay between magnetic field, transformation strain, and coarsening on variant selection in L10-type FePd

International Nuclear Information System (INIS)

Ueshima, N.; Yasuda, H.; Yoshiya, M.; Fukuda, T.; Kakeshita, T.

2014-01-01

Variant selection of L1 0 -type ferromagnetic alloys has been numerically investigated using the phase-field modeling, to clarify the phenomena at greater temporal and spatial resolution and to reveal the underlying mechanism. The duration for which the external magnetic field is effective is found to be very short, and variant selection is significantly affected by not only direct response to the external magnetic field but also their interplay between the field, intrinsic transformation strain, and various thermodynamic energy components involved in the course of microstructure evolution. The detailed mechanism of the interplay was quantitatively analyzed in terms of the driving force for the variant selection, by partitioning it into the various energy components. Careful examination of the variant selection at the very early stage revealed that the slight difference in size and configuration of variants during disorder-to-order transition realized by the interplay between transformation strain and external field is essentially needed before proceeding to the latter stage of the variant selection driven by interface energy

Spin-selective depopulation of triplet sublevels in rapidly rotating triplet exciplexes detected by a heavy-atom-induced magnetic field effect

OpenAIRE

Steiner, Ulrich

1980-01-01

A mechanism is presented explaining a reported heavy-atom-induced magnetic field effect as a consequence of non-equilibrium triplet sublevel population in an intermediate exciplex. The triplet exciplex spin polarization is induced by sub-level-selective intersystem crossing from the exciplex triplet to its singlet ground state and is decreased by an external magnetic field. The theory accounts almost quantitatively for the observed influence of magnetic field strength and heavy-atom substitue...

Magnetic moment densities in selected UTX compounds

Czech Academy of Sciences Publication Activity Database

Javorský, P.; Schweizer, J.; Givord, F.; Boucherle, J.-X.; Andreev, Alexander V.; Diviš, M.; Lelievre-Berna, E.; Sechovský, V.

2004-01-01

Roč. 350, - (2004), e131-e134 ISSN 0921-4526 R&D Projects: GA ČR GA202/03/0550 Institutional research plan: CEZ:AV0Z1010914 Keywords : uranium compound * polarized neutron scattering * magnetic moment Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.679, year: 2004

Interfacing 3D magnetic twisting cytometry with confocal fluorescence microscopy to image force responses in living cells.

Science.gov (United States)

Zhang, Yuejin; Wei, Fuxiang; Poh, Yeh-Chuin; Jia, Qiong; Chen, Junjian; Chen, Junwei; Luo, Junyu; Yao, Wenting; Zhou, Wenwen; Huang, Wei; Yang, Fang; Zhang, Yao; Wang, Ning

2017-07-01

Cells and tissues can undergo a variety of biological and structural changes in response to mechanical forces. Only a few existing techniques are available for quantification of structural changes at high resolution in response to forces applied along different directions. 3D-magnetic twisting cytometry (3D-MTC) is a technique for applying local mechanical stresses to living cells. Here we describe a protocol for interfacing 3D-MTC with confocal fluorescence microscopy. In 3D-MTC, ferromagnetic beads are bound to the cell surface via surface receptors, followed by their magnetization in any desired direction. A magnetic twisting field in a different direction is then applied to generate rotational shear stresses in any desired direction. This protocol describes how to combine magnetic-field-induced mechanical stimulation with confocal fluorescence microscopy and provides an optional extension for super-resolution imaging using stimulated emission depletion (STED) nanoscopy. This technology allows for rapid real-time acquisition of a living cell's mechanical responses to forces via specific receptors and for quantifying structural and biochemical changes in the same cell using confocal fluorescence microscopy or STED. The integrated 3D-MTC-microscopy platform takes ∼20 d to construct, and the experimental procedures require ∼4 d when carried out by a life sciences graduate student.

Tantalum Nitride Electron-Selective Contact for Crystalline Silicon Solar Cells

KAUST Repository

Yang, Xinbo

2018-04-19

Minimizing carrier recombination at contact regions by using carrier‐selective contact materials, instead of heavily doping the silicon, has attracted considerable attention for high‐efficiency, low‐cost crystalline silicon (c‐Si) solar cells. A novel electron‐selective, passivating contact for c‐Si solar cells is presented. Tantalum nitride (TaN x ) thin films deposited by atomic layer deposition are demonstrated to provide excellent electron‐transporting and hole‐blocking properties to the silicon surface, due to their small conduction band offset and large valence band offset. Thin TaNx interlayers provide moderate passivation of the silicon surfaces while simultaneously allowing a low contact resistivity to n‐type silicon. A power conversion efficiency (PCE) of over 20% is demonstrated with c‐Si solar cells featuring a simple full‐area electron‐selective TaNx contact, which significantly improves the fill factor and the open circuit voltage (Voc) and hence provides the higher PCE. The work opens up the possibility of using metal nitrides, instead of metal oxides, as carrier‐selective contacts or electron transport layers for photovoltaic devices.

Comparison of 2-D Magnetic Designs of Selected Coil Configurations for the Next European Dipole (NED)

CERN Document Server

Toral, F; Felice, H; Fessia, Paolo; Loveridge, P W; Regis, Federico; Rochford, J; Sanz, S; Schwerg, Nikolai; Védrine, P; Völlinger, Christine

2007-01-01

The Next European Dipole (NED) activity is developing a high-performance Nb$_{3}$Sn wire (aiming at a non-copper critical current density of 1500 A/mm2 at 4.2 K and 15 T), within the framework of the Coordinated Accelerator Research in Europe (CARE) project. This activity is expected to lead to the fabrication of a large aperture, high field dipole magnet. In preparation for this phase, a Working Group on Magnet Design and Optimization (MDO) has been established to propose an optimal design. Other parallel Work Packages are concentrating on relevant topics, such as quench propagation simulation, innovative insulation techniques, and heat transfer measurements. In a first stage, the MDO Working Group has selected a number of coil configurations to be studied, together with salient parameters and features to be considered during the evaluation: the field quality, the superconductor efficiency, the conductor peak field, the stored magnetic energy, the Lorentz Forces and the fabrication difficulties. 2-D magnetic...

Umbilical cord mesenchymal stem cells labeled with multimodal iron oxide nanoparticles with fluorescent and magnetic properties: application for in vivo cell tracking.

Science.gov (United States)

Sibov, Tatiana T; Pavon, Lorena F; Miyaki, Liza A; Mamani, Javier B; Nucci, Leopoldo P; Alvarim, Larissa T; Silveira, Paulo H; Marti, Luciana C; Gamarra, Lf

2014-01-01

Here we describe multimodal iron oxide nanoparticles conjugated to Rhodamine-B (MION-Rh), their stability in culture medium, and subsequent validation of an in vitro protocol to label mesenchymal stem cells from umbilical cord blood (UC-MSC) with MION-Rh. These cells showed robust labeling in vitro without impairment of their functional properties, the viability of which were evaluated by proliferation kinetic and ultrastructural analyzes. Thus, labeled cells were infused into striatum of adult male rats of animal model that mimic late onset of Parkinson's disease and, after 15 days, it was observed that cells migrated along the medial forebrain bundle to the substantia nigra as hypointense spots in T2 magnetic resonance imaging. These data were supported by short-term magnetic resonance imaging. Studies were performed in vivo, which showed that about 5 × 10(5) cells could be efficiently detected in the short term following infusion. Our results indicate that these labeled cells can be efficiently tracked in a neurodegenerative disease model.

Umbilical cord mesenchymal stem cells labeled with multimodal iron oxide nanoparticles with fluorescent and magnetic properties: application for in vivo cell tracking

Science.gov (United States)

Sibov, Tatiana T; Pavon, Lorena F; Miyaki, Liza A; Mamani, Javier B; Nucci, Leopoldo P; Alvarim, Larissa T; Silveira, Paulo H; Marti, Luciana C; Gamarra, LF

2014-01-01

Here we describe multimodal iron oxide nanoparticles conjugated to Rhodamine-B (MION-Rh), their stability in culture medium, and subsequent validation of an in vitro protocol to label mesenchymal stem cells from umbilical cord blood (UC-MSC) with MION-Rh. These cells showed robust labeling in vitro without impairment of their functional properties, the viability of which were evaluated by proliferation kinetic and ultrastructural analyzes. Thus, labeled cells were infused into striatum of adult male rats of animal model that mimic late onset of Parkinson’s disease and, after 15 days, it was observed that cells migrated along the medial forebrain bundle to the substantia nigra as hypointense spots in T2 magnetic resonance imaging. These data were supported by short-term magnetic resonance imaging. Studies were performed in vivo, which showed that about 5 × 105 cells could be efficiently detected in the short term following infusion. Our results indicate that these labeled cells can be efficiently tracked in a neurodegenerative disease model. PMID:24531365

GEM-loaded magnetic albumin nanospheres modified with cetuximab for simultaneous targeting, magnetic resonance imaging, and double-targeted thermochemotherapy of pancreatic cancer cells

Directory of Open Access Journals (Sweden)

Wang L

2015-03-01

Full Text Available Ling Wang,1 Yanli An,2 Chenyan Yuan,3 Hao Zhang,2 Chen Liang,2 Fengan Ding,2 Qi Gao,1 Dongsheng Zhang4 1Department of Ultrasonography, Zhong Da Hospital, Medical School, Southeast University, Nanjing, People’s Republic of China; 2Medical School, Southeast University, Nanjing, People’s Republic of China; 3Department of Clinical Laboratory, Zhong Da Hospital, Medical School, Southeast University, Nanjing, People’s Republic of China; 4Jiangsu Key Laboratory for Biomaterials and Devices, Medical School, Southeast University, Nanjing, People’s Republic of China Background: Targeted delivery is a promising strategy to improve the diagnostic imaging and therapeutic effect of cancers. In this paper, novel cetuximab (C225-conjugated, gemcitabine (GEM-containing magnetic albumin nanospheres (C225-GEM/MANs were fabricated and applied as a theranostic nanocarrier to conduct simultaneous targeting, magnetic resonance imaging (MRI, and double-targeted thermochemotherapy against pancreatic cancer cells. Methods: Fe3O4 nanoparticles (NPs and GEM co-loaded albumin nanospheres (GEM/MANs were prepared, and then C225 was further conjugated to synthesize C225-GEM/MANs. Their morphology, mean particle size, GEM encapsulation ratio, specific cell-binding ability, and thermal dynamic profiles were characterized. The effects of discriminating different EGFR-expressing pancreatic cancer cells (AsPC-1 and MIA PaCa-2 and monitoring cellular targeting effects were assessed by targeted MRI. Lastly, the antitumor efficiency of double/C225/magnetic-targeted and nontargeted thermochemotherapy was compared with chemotherapy alone using 3-(4, 5-dimethyl-2-thiazolyl-2,5-diphenyl-2H-tetrazolium bromide (MTT and flow cytometry (FCM assay. Results: When treated with targeted nanospheres, AsPC-1 cells showed a significantly less intense MRI T2 signal than MIA PaCa-2 cells, while both cells had similar signal strength when incubated with nontargeted nanospheres. T2 signal

Magnetic Gold Nanoparticle-Labeled Heparanase Monoclonal Antibody and its Subsequent Application for Tumor Magnetic Resonance Imaging

Science.gov (United States)

Li, Ning; Jie, Meng-Meng; Yang, Min; Tang, Li; Chen, Si-Yuan; Sun, Xue-Mei; Tang, Bo; Yang, Shi-Ming

2018-04-01

Heparanase (HPA) is ubiquitously expressed in various metastatic malignant tumors; previous studies have demonstrated that HPA was a potential tumor-associated antigen (TAA) for tumor immunotherapy. We sought to evaluate the feasibility of HPA as a common TAA for magnetic resonance imaging (MRI) of tumor metastasis and its potential application in tumor molecular imaging. We prepared a targeted probe based on magnetic gold nanoparticles coupled with an anti-HPA antibody for the specific detection of HPA by MRI. The specificity of the targeted probe was validated in vitro by incubation of the probe with various tumor cells, and the probe was able to selectively detect HPA (+) cells. We found the probes displayed significantly reduced signal intensity in several tumor cells, and the signal intensity decreased significantly after the targeted probe was injected in tumor-bearing nude mice. In the study, we demonstrated that the HPA&GoldMag probe had excellent physical and chemical properties and immune activities and could specifically target many tumor cell tissues both in vitro and in vivo. This may provide an experimental base for molecular imaging of tumor highly expressing heparanase using HPA mAbs.

Biological effects of static magnetic fields: a selective review with emphasis on risk assessment

International Nuclear Information System (INIS)

Easterly, C.E.

1982-04-01

Rather than focusing on literature per se, the current study determines the status of magnetic field information that is applicable to risk assessment. Hence, an attempt is made to identify both the literature that is useful to the goal of risk assessment and a framework within which risk assessment methodologies can be derived. From this selected review, it is concluded that three areas exist for which adequate information can be found to begin modelling: disease induction, reproduction and development, and cardiovascular response. The first two are supported by a combination of positive and negative findings and the last by a calculational technique which utilizes the physically well-known principle of flow retardation for a conducting fluid moving through a magnetic field

Biological effects of static magnetic fields: a selective review with emphasis on risk assessment

Energy Technology Data Exchange (ETDEWEB)

Easterly, C. E.

1982-04-01

Rather than focusing on literature per se, the current study determines the status of magnetic field information that is applicable to risk assessment. Hence, an attempt is made to identify both the literature that is useful to the goal of risk assessment and a framework within which risk assessment methodologies can be derived. From this selected review, it is concluded that three areas exist for which adequate information can be found to begin modelling: disease induction, reproduction and development, and cardiovascular response. The first two are supported by a combination of positive and negative findings and the last by a calculational technique which utilizes the physically well-known principle of flow retardation for a conducting fluid moving through a magnetic field.

Human induced pluripotent stem cells labeled with fluorescent magnetic nanoparticles for targeted imaging and hyperthermia therapy for gastric cancer

International Nuclear Information System (INIS)

Li, Chao; Ruan, Jing; Yang, Meng; Pan, Fei; Gao, Guo; Qu, Su; Shen, You-Lan; Dang, Yong-Jun; Wang, Kan; Jin, Wei-Lin; Cui, Da-Xiang

2015-01-01

Human induced pluripotent stem (iPS) cells exhibit great potential for generating functional human cells for medical therapies. In this paper, we report for use of human iPS cells labeled with fluorescent magnetic nanoparticles (FMNPs) for targeted imaging and synergistic therapy of gastric cancer cells in vivo. Human iPS cells were prepared and cultured for 72 h. The culture medium was collected, and then was co-incubated with MGC803 cells. Cell viability was analyzed by the MTT method. FMNP-labeled human iPS cells were prepared and injected into gastric cancer-bearing nude mice. The mouse model was observed using a small-animal imaging system. The nude mice were irradiated under an external alternating magnetic field and evaluated using an infrared thermal mapping instrument. Tumor sizes were measured weekly. iPS cells and the collected culture medium inhibited the growth of MGC803 cells. FMNP-labeled human iPS cells targeted and imaged gastric cancer cells in vivo, as well as inhibited cancer growth in vivo through the external magnetic field. FMNP-labeled human iPS cells exhibit considerable potential in applications such as targeted dual-mode imaging and synergistic therapy for early gastric cancer

Electrical performance of a string of magnets representing a half-cell of the LHC machine

International Nuclear Information System (INIS)

Rodriguez-Mateos, F.; Coull, L.; Dahlerup-Petersen, K.; Hagedorn, D.; Krainz, G.; Rijllart, A.; McInturff, A.

1996-01-01

Tests have been carried out on a string of prototype superconducting magnets, consisting of one double-quadrupole and two double-dipoles forming the major part of a half-cell of the LHC machine. The magnets are protected individually by cold diodes and quench heaters. The electrical aspects of these tests are described here. The performance during quench of the protection diodes and the associated interconnections was studied. Tests determined the magnet quench performance in training and at different ramp-rates, and investigated the inter-magnet propagation of quenches. Current lead and inter-magnet contact resistances were controlled and the performance of the power converter and the dump switches assessed

Electrical performance of a string of magnets representing a half-cell of the LHC machine

International Nuclear Information System (INIS)

Rodriguez-Mateos, F.; Coull, L.; Dahlerup-Petersen, K.; Hagedorn, D.; Krainz, G.; Rijllart, A.; McInturff, A.

1995-01-01

Tests have been carried out on a string prototype superconducting magnets, consisting of one double-quadrupole and two double-dipoles forming the major part of a half-cell of the LHC machine. The magnets are protected individually by ''cold diodes'' and quench heaters. The electrical aspects of these tests are described here. The performance during quench of the protection diodes and the associated interconnections was studied. Tests determined the magnet quench performance in training and at different ramp-rates, and investigated the inter-magnet propagation of quenches. Current lead and inter-magnet contact resistances were controlled and the performance of the power converter and the dump switches assessed

Supplementation of Nucleosides During Selection can Reduce Sequence Variant Levels in CHO Cells Using GS/MSX Selection System.

Science.gov (United States)

Tang, Danming; Lam, Cynthia; Louie, Salina; Hoi, Kam Hon; Shaw, David; Yim, Mandy; Snedecor, Brad; Misaghi, Shahram

2018-01-01

In the process of generating stable monoclonal antibody (mAb) producing cell lines, reagents such as methotrexate (MTX) or methionine sulfoximine (MSX) are often used. However, using such selection reagent(s) increases the possibility of having higher occurrence of sequence variants in the expressed antibody molecules due to the effects of MTX or MSX on de novo nucleotide synthesis. Since MSX inhibits glutamine synthase (GS) and results in both amino acid and nucleoside starvation, it is questioned whether supplementing nucleosides into the media could lower sequence variant levels without affecting titer. The results show that the supplementation of nucleosides to the media during MSX selection decreased genomic DNA mutagenesis rates in the selected cells, probably by reducing nucleotide mis-incorporation into the DNA. Furthermore, addition of nucleosides enhance clone recovery post selection and does not affect antibody expression. It is further observed that nucleoside supplements lowered DNA mutagenesis rates only at the initial stage of the clone selection and do not have any effect on DNA mutagenesis rates after stable cell lines are established. Therefore, the data suggests that addition of nucleosides during early stages of MSX selection can lower sequence variant levels without affecting titer or clone stability in antibody expression. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of low static magnetic field on osteogenic and adipogenic differentiation potential of human adipose stromal/stem cells

Energy Technology Data Exchange (ETDEWEB)

Marędziak, Monika, E-mail: monika.maredziak@gmail.com [Faculty of Veterinary Medicine, University of Environmental and Life Sciences, Wrocław (Poland); Wroclaw Research Centre EIT+, Wrocław (Poland); Śmieszek, Agnieszka, E-mail: smieszek.agnieszka@gmail.com [Wroclaw Research Centre EIT+, Wrocław (Poland); Faculty of Biology, University of Environmental and Life Sciences, Wrocław (Poland); Tomaszewski, Krzysztof A., E-mail: krtomaszewski@gmail.com [Department of Anatomy, Jagiellonian University Medical College, Krakow (Poland); Lewandowski, Daniel, E-mail: daniel.lewandowski@pwr.wroc.pl [Institute of Materials Science and Applied Mechanics, Wroclaw University of Technology, Wroclaw (Poland); Marycz, Krzysztof, E-mail: krzysztofmarycz@interia.pl [Wroclaw Research Centre EIT+, Wrocław (Poland); Faculty of Biology, University of Environmental and Life Sciences, Wrocław (Poland)

2016-01-15

The aim of this work was to investigate the effects of static magnetic field (SMF) on the osteogenic properties of human adipose derived mesenchymal stem cells (hASCs). In this study in seven days viability assay we examined the impact of SMF on cells proliferation rate, population doubling time, and ability to form single-cell derived colonies. We have also examined cells' morphology, ultrastructure and osteogenic properties on the protein as well as mRNA level. We established a complex approach, which enabled us to obtain information about SMF and hASCs potential in the context of differentiation into osteogenic and adipogenic lineages. We demonstrated that SMF enhances both viability and osteogenic properties of hASCs through higher proliferation factor and shorter population doubling time. We have also observed asymmetrically positioned nuclei and organelles after SMF exposition. With regards to osteogenic properties we observed increased levels of osteogenic markers i.e. osteopontin, osteocalcin and increased ability to form osteonodules with positive reaction to Alizarin Red dye. We have also shown that SMF besides enhancing osteogenic properties of hASCs, simultaneously decreases their ability to differentiate into adipogenic lineage. Our results clearly show a direct influence of SMF on the osteogenic potential of hASCs. These results provide key insights into the role of SMF on their cellular fate and properties. - Graphical abstract: Influence of static magnetic field on viability and differentiation properties of human adipose derived mesenchymal stem cells. Abbreviations: SMF – static magnetic field; hASCs – human adipose derived mesenchymal stem cells; PF – proliferation factor; PDT – population doubling time; CFU-E –> colony forming unit efficiency; OPN – osteopontin; OCL – osteocalcin; Col – collagen type I; BMP-2 – bone morphogenetic protein 2; Ca – calcium; P – phosphorus. - Highlights: • Effects of static

The effect of low static magnetic field on osteogenic and adipogenic differentiation potential of human adipose stromal/stem cells

International Nuclear Information System (INIS)

Marędziak, Monika; Śmieszek, Agnieszka; Tomaszewski, Krzysztof A.; Lewandowski, Daniel; Marycz, Krzysztof

2016-01-01

The aim of this work was to investigate the effects of static magnetic field (SMF) on the osteogenic properties of human adipose derived mesenchymal stem cells (hASCs). In this study in seven days viability assay we examined the impact of SMF on cells proliferation rate, population doubling time, and ability to form single-cell derived colonies. We have also examined cells' morphology, ultrastructure and osteogenic properties on the protein as well as mRNA level. We established a complex approach, which enabled us to obtain information about SMF and hASCs potential in the context of differentiation into osteogenic and adipogenic lineages. We demonstrated that SMF enhances both viability and osteogenic properties of hASCs through higher proliferation factor and shorter population doubling time. We have also observed asymmetrically positioned nuclei and organelles after SMF exposition. With regards to osteogenic properties we observed increased levels of osteogenic markers i.e. osteopontin, osteocalcin and increased ability to form osteonodules with positive reaction to Alizarin Red dye. We have also shown that SMF besides enhancing osteogenic properties of hASCs, simultaneously decreases their ability to differentiate into adipogenic lineage. Our results clearly show a direct influence of SMF on the osteogenic potential of hASCs. These results provide key insights into the role of SMF on their cellular fate and properties. - Graphical abstract: Influence of static magnetic field on viability and differentiation properties of human adipose derived mesenchymal stem cells. Abbreviations: SMF – static magnetic field; hASCs – human adipose derived mesenchymal stem cells; PF – proliferation factor; PDT – population doubling time; CFU-E –> colony forming unit efficiency; OPN – osteopontin; OCL – osteocalcin; Col – collagen type I; BMP-2 – bone morphogenetic protein 2; Ca – calcium; P – phosphorus. - Highlights: • Effects of static

Chromium Trioxide Hole-Selective Heterocontacts for Silicon Solar Cells.

Science.gov (United States)

Lin, Wenjie; Wu, Weiliang; Liu, Zongtao; Qiu, Kaifu; Cai, Lun; Yao, Zhirong; Ai, Bin; Liang, Zongcun; Shen, Hui

2018-04-25

A high recombination rate and high thermal budget for aluminum (Al) back surface field are found in the industrial p-type silicon solar cells. Direct metallization on lightly doped p-type silicon, however, exhibits a large Schottky barrier for the holes on the silicon surface because of Fermi-level pinning effect. As a result, low-temperature-deposited, dopant-free chromium trioxide (CrO x , x solar cell as a hole-selective contact at the rear surface. By using 4 nm CrO x between the p-type silicon and Ag, we achieve a reduction of the contact resistivity for the contact of Ag directly on p-type silicon. For further improvement, we utilize a CrO x (2 nm)/Ag (30 nm)/CrO x (2 nm) multilayer film on the contact between Ag and p-type crystalline silicon (c-Si) to achieve a lower contact resistance (40 mΩ·cm 2 ). The low-resistivity Ohmic contact is attributed to the high work function of the uniform CrO x film and the depinning of the Fermi level of the SiO x layer at the silicon interface. Implementing the advanced hole-selective contacts with CrO x /Ag/CrO x on the p-type silicon solar cell results in a power conversion efficiency of 20.3%, which is 0.1% higher than that of the cell utilizing 4 nm CrO x . Compared with the commercialized p-type solar cell, the novel CrO x -based hole-selective transport material opens up a new possibility for c-Si solar cells using high-efficiency, low-temperature, and dopant-free deposition techniques.

Can Lucifer Yellow Indicate Correct Permeability of Biological Cell Membrane under An Electric and Magnetic Field?

OpenAIRE

Tahereh Pourmirjafari Firoozabadi; Zeinab Shankayi; Azam Izadi; Seyed Mohammad Pourmirjafari Firoozabadi

2015-01-01

The effect of external magnetic and electric fields, in the range of electroporation and magnetoporation, on Lucifer Yellow (LY) fluorescence in the absence of cells is studied. Electric-field-induced quenching and magnetic field-induced increase are observed for fluorescence intensity of LY. Regard to the fact that the variation of field-induced fluorescence, even in the absence of cells, can be observed, the application of LY, as a marker, is debatable in electroporation and magnetoporation...

Expression of Heat Shock Proteins in Human Fibroblast Cells under Magnetic Resonant Coupling Wireless Power Transfer

Directory of Open Access Journals (Sweden)

Kohei Mizuno

2015-10-01

Full Text Available Since 2007, resonant coupling wireless power transfer (WPT technology has been attracting attention and has been widely researched for practical use. Moreover, dosimetric evaluation has also been discussed to evaluate the potential health risks of the electromagnetic field from this WPT technology based on the International Commission on Non-Ionizing Radiation Protection (ICNIRP guidelines. However, there has not been much experimental evaluation of the potential health risks of this WPT technology. In this study, to evaluate whether magnetic resonant coupling WPT induces cellular stress, we focused on heat shock proteins (Hsps and determined the expression level of Hsps 27, 70 and 90 in WI38VA13 subcloned 2RA human fibroblast cells using a western blotting method. The expression level of Hsps under conditions of magnetic resonant coupling WPT for 24 h was not significantly different compared with control cells, although the expression level of Hsps for cells exposed to heat stress conditions was significantly increased. These results suggested that exposure to magnetic resonant coupling WPT did not cause detectable cell stress.

Hypericin-bearing magnetic iron oxide nanoparticles for selective drug delivery in photodynamic ther

OpenAIRE

Unterweger, H; Subatzus, D; Tietze, R; Janko, C; Poettler, M; Stiegelschmitt, A; Schuster, M; Maake, C; Boccaccini, A R; Alexiou, C

2015-01-01

Combining the concept of magnetic drug targeting and photodynamic therapy is a promising approach for the treatment of cancer. A high selectivity as well as significant fewer side effects can be achieved by this method, since the therapeutic treatment only takes place in the area where accumulation of the particles by an external electromagnet and radiation by a laser system overlap. In this article, a novel hypericin-bearing drug delivery system has been developed by synthesis of superparama...

Antibodies and Selection of Monoclonal Antibodies.

Science.gov (United States)

Hanack, Katja; Messerschmidt, Katrin; Listek, Martin

Monoclonal antibodies are universal binding molecules with a high specificity for their target and are indispensable tools in research, diagnostics and therapy. The biotechnological generation of monoclonal antibodies was enabled by the hybridoma technology published in 1975 by Köhler and Milstein. Today monoclonal antibodies are used in a variety of applications as flow cytometry, magnetic cell sorting, immunoassays or therapeutic approaches. First step of the generation process is the immunization of the organism with appropriate antigen. After a positive immune response the spleen cells are isolated and fused with myeloma cells in order to generate stable, long-living antibody-producing cell lines - hybridoma cells. In the subsequent identification step the culture supernatants of all hybridoma cells are screened weekly for the production of the antibody of interest. Hybridoma cells producing the antibody of interest are cloned by limited dilution till a monoclonal hybridoma is found. This is a very time-consuming and laborious process and therefore different selection strategies were developed since 1975 in order to facilitate the generation of monoclonal antibodies. Apart from common automation of pipetting processes and ELISA testing there are some promising approaches to select the right monoclonal antibody very early in the process to reduce time and effort of the generation. In this chapter different selection strategies for antibody-producing hybridoma cells are presented and analysed regarding to their benefits compared to conventional limited dilution technology.

Structure-activity relationship of 9-methylstreptimidone, a compound that induces apoptosis selectively in adult T-cell leukemia cells.

Science.gov (United States)

Takeiri, Masatoshi; Ota, Eisuke; Nishiyama, Shigeru; Kiyota, Hiromasa; Umezawa, Kazuo

2012-01-01

We previously reported that 9-methylstreptimidone, a piperidine compound isolated from a culture filtrate of Streptomyces, induces apoptosis selectively in adult T-cell leukemia cells. It was screened for a compound that inhibits LPS-induced NF-kappaB and NO production in mouse macrophages. However, 9-methystreptimidone is poorly obtained from the producing microorganism and difficult to synthesize. Therefore, in the present research, we studied the structure-activity relationship to look for new selective inhibitors. We found that the structure of the unsaturated hydrophobic portion of 9-methylstreptimidone was essential for the inhibition of LPS-induced NO production. Among the 9-methylstreptimidone-related compounds tested, (+/-)-4,alpha-diepi-streptovitacin A inhibited NO production in macrophage-like cells as potently as 9-methylstreptimidone and without cellular toxicity. Moreover, this compound selectively induced apoptosis in adult T-cell leukemia MT-1 cells.

CARbodies: Human Antibodies Against Cell Surface Tumor Antigens Selected From Repertoires Displayed on T Cell Chimeric Antigen Receptors

Directory of Open Access Journals (Sweden)

Vanesa Alonso-Camino

2013-01-01

Full Text Available A human single-chain variable fragment (scFv antibody library was expressed on the surface of human T cells after transduction with lentiviral vectors (LVs. The repertoire was fused to a first-generation T cell receptor ζ (TCRζ-based chimeric antigen receptor (CAR. We used this library to isolate antibodies termed CARbodies that recognize antigens expressed on the tumor cell surface in a proof-of-principle system. After three rounds of activation-selection there was a clear repertoire restriction, with the emergence dominant clones. The CARbodies were purified from bacterial cultures as soluble and active proteins. Furthermore, to validate its potential application for adoptive cell therapy, human T cells were transduced with a LV encoding a second-generation costimulatory CAR (CARv2 bearing the selected CARbodies. Transduced human primary T cells expressed significant levels of the CARbodies-based CARv2 fusion protein on the cell surface, and importantly could be specifically activated, after stimulation with tumor cells. This approach is a promising tool for the generation of antibodies fully adapted to the display format (CAR and the selection context (cell synapse, which could extend the scope of current adoptive cell therapy strategies with CAR-redirected T cells.

How nonuniform contact profiles of T cell receptors modulate thymic selection outcomes

Science.gov (United States)

Chen, Hanrong; Chakraborty, Arup K.; Kardar, Mehran

2018-03-01

T cell receptors (TCRs) bind foreign or self-peptides attached to major histocompatibility complex (MHC) molecules, and the strength of this interaction determines T cell activation. Optimizing the ability of T cells to recognize a diversity of foreign peptides yet be tolerant of self-peptides is crucial for the adaptive immune system to properly function. This is achieved by selection of T cells in the thymus, where immature T cells expressing unique, stochastically generated TCRs interact with a large number of self-peptide-MHC; if a TCR does not bind strongly enough to any self-peptide-MHC, or too strongly with at least one self-peptide-MHC, the T cell dies. Past theoretical work cast thymic selection as an extreme value problem and characterized the statistical enrichment or depletion of amino acids in the postselection TCR repertoire, showing how T cells are selected to be able to specifically recognize peptides derived from diverse pathogens yet have limited self-reactivity. Here, we investigate how the diversity of the postselection TCR repertoire is modified when TCRs make nonuniform contacts with peptide-MHC. Specifically, we were motivated by recent experiments showing that amino acids at certain positions of a TCR sequence have large effects on thymic selection outcomes, and crystal structure data that reveal a nonuniform contact profile between a TCR and its peptide-MHC ligand. Using a representative TCR contact profile as an illustration, we show via simulations that the statistical enrichment or depletion of amino acids now varies by position according to the contact profile, and, importantly, it depends on the implementation of nonuniform contacts during thymic selection. We explain these nontrivial results analytically. Our study has implications for understanding the selection forces that shape the functionality of the postselection TCR repertoire.

Transducer selection and application in magnetoacoustic tomography with magnetic induction

International Nuclear Information System (INIS)

Zhou, Yuqi; Wang, Jiawei; Ma, Qingyu; Sun, Xiaodong; Zhang, Dong

2016-01-01

As an acoustic receiver, transducer plays a vital role in signal acquisition and image reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI). In order to optimize signal acquisition, the expressions of acoustic pressure detection and waveform collection are theoretically studied based on the radiation theory of acoustic dipole and the reception pattern of transducer. Pressure distributions are simulated for a cylindrical phantom model using a planar piston transducer with different radii and bandwidths. The proposed theory is also verified by the experimental measurements of acoustic waveform detection for an aluminum foil cylinder. It is proved that acoustic pressure with sharp and clear boundary peaks can be detected by the large-radius transducer with wide bandwidth, reflecting the differential of the induced Lorentz force accurately, which is helpful for precise conductivity reconstruction. To detect acoustic pressure with acceptable pressure amplitude, peak pressure ratio, amplitude ratio, and improved signal to noise ratio, the scanning radius of 5–10 times the radius of the object should be selected to improve the accuracy of image reconstruction. This study provides a theoretical and experimental basis for transducer selection and application in MAT-MI to obtain reconstructed images with improved resolution and definition.

Transducer selection and application in magnetoacoustic tomography with magnetic induction

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yuqi; Wang, Jiawei; Ma, Qingyu, E-mail: maqingyu@njnu.edu.cn [Key Laboratory of Optoelectronics of Jiangsu Province, School of Physics and Technology, Nanjing Normal University, Nanjing 210023 (China); Sun, Xiaodong [China Key System & Integrated Circuit Co., Ltd., Wuxi 214072 (China); Zhang, Dong [Laboratory of Modern Acoustics of MOE, Institute of Acoustics, Nanjing University, Nanjing 210093 (China)

2016-03-07

As an acoustic receiver, transducer plays a vital role in signal acquisition and image reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI). In order to optimize signal acquisition, the expressions of acoustic pressure detection and waveform collection are theoretically studied based on the radiation theory of acoustic dipole and the reception pattern of transducer. Pressure distributions are simulated for a cylindrical phantom model using a planar piston transducer with different radii and bandwidths. The proposed theory is also verified by the experimental measurements of acoustic waveform detection for an aluminum foil cylinder. It is proved that acoustic pressure with sharp and clear boundary peaks can be detected by the large-radius transducer with wide bandwidth, reflecting the differential of the induced Lorentz force accurately, which is helpful for precise conductivity reconstruction. To detect acoustic pressure with acceptable pressure amplitude, peak pressure ratio, amplitude ratio, and improved signal to noise ratio, the scanning radius of 5–10 times the radius of the object should be selected to improve the accuracy of image reconstruction. This study provides a theoretical and experimental basis for transducer selection and application in MAT-MI to obtain reconstructed images with improved resolution and definition.

Intraclonal Cell Expansion and Selection Driven by B Cell Receptor in Chronic Lymphocytic Leukemia

Science.gov (United States)

Colombo, Monica; Cutrona, Giovanna; Reverberi, Daniele; Fabris, Sonia; Neri, Antonino; Fabbi, Marina; Quintana, Giovanni; Quarta, Giovanni; Ghiotto, Fabio; Fais, Franco; Ferrarini, Manlio

2011-01-01

The mutational status of the immunoglobulin heavy-chain variable region (IGHV) genes utilized by chronic lymphocytic leukemia (CLL) clones defines two disease subgroups. Patients with unmutated IGHV have a more aggressive disease and a worse outcome than patients with cells having somatic IGHV gene mutations. Moreover, up to 30% of the unmutated CLL clones exhibit very similar or identical B cell receptors (BcR), often encoded by the same IG genes. These “stereotyped” BcRs have been classified into defined subsets. The presence of an IGHV gene somatic mutation and the utilization of a skewed gene repertoire compared with normal B cells together with the expression of stereotyped receptors by unmutated CLL clones may indicate stimulation/selection by antigenic epitopes. This antigenic stimulation may occur prior to or during neoplastic transformation, but it is unknown whether this stimulation/selection continues after leukemogenesis has ceased. In this study, we focused on seven CLL cases with stereotyped BcR Subset #8 found among a cohort of 700 patients; in six, the cells expressed IgG and utilized IGHV4-39 and IGKV1-39/IGKV1D-39 genes, as reported for Subset #8 BcR. One case exhibited special features, including expression of IgM or IgG by different subclones consequent to an isotype switch, allelic inclusion at the IGH locus in the IgM-expressing cells and a particular pattern of cytogenetic lesions. Collectively, the data indicate a process of antigenic stimulation/selection of the fully transformed CLL cells leading to the expansion of the Subset #8 IgG-bearing subclone. PMID:21541442

Magnetizable stent-grafts enable endothelial cell capture

Energy Technology Data Exchange (ETDEWEB)

Tefft, Brandon J. [Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Uthamaraj, Susheil [Division of Engineering, Mayo Clinic, Rochester, MN (United States); Harburn, J. Jonathan [School of Medicine, Pharmacy and Health, Durham University, Stockton-on-Tees (United Kingdom); Hlinomaz, Ota [Department of Cardioangiology, St. Anne' s University Hospital, Brno (Czech Republic); Lerman, Amir [Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Dragomir-Daescu, Dan [Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN (United States); Sandhu, Gurpreet S., E-mail: sandhu.gurpreet@mayo.edu [Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States)

2017-04-01

Emerging nanotechnologies have enabled the use of magnetic forces to guide the movement of magnetically-labeled cells, drugs, and other therapeutic agents. Endothelial cells labeled with superparamagnetic iron oxide nanoparticles (SPION) have previously been captured on the surface of magnetizable 2205 duplex stainless steel stents in a porcine coronary implantation model. Recently, we have coated these stents with electrospun polyurethane nanofibers to fabricate prototype stent-grafts. Facilitated endothelialization may help improve the healing of arteries treated with stent-grafts, reduce the risk of thrombosis and restenosis, and enable small-caliber applications. When placed in a SPION-labeled endothelial cell suspension in the presence of an external magnetic field, magnetized stent-grafts successfully captured cells to the surface regions adjacent to the stent struts. Implantation within the coronary circulation of pigs (n=13) followed immediately by SPION-labeled autologous endothelial cell delivery resulted in widely patent devices with a thin, uniform neointima and no signs of thrombosis or inflammation at 7 days. Furthermore, the magnetized stent-grafts successfully captured and retained SPION-labeled endothelial cells to select regions adjacent to stent struts and between stent struts, whereas the non-magnetized control stent-grafts did not. Early results with these prototype devices are encouraging and further refinements will be necessary in order to achieve more uniform cell capture and complete endothelialization. Once optimized, this approach may lead to more rapid and complete healing of vascular stent-grafts with a concomitant improvement in long-term device performance. - Highlights: • Magnetic stent-grafts were made from 2205 steel stents and polyurethane nanofibers. • Stent-grafts remained patent and formed a thin and uniform neointima when implanted. • Stent-grafts captured endothelial cells labeled with magnetic nanoparticles. �

High pressure cells for magnetic measurements - destruction and functional tests

Czech Academy of Sciences Publication Activity Database

Kamarád, Jiří; Machátová, Zuzana; Arnold, Zdeněk

2004-01-01

Roč. 75, č. 11 (2004), s. 5022-5025 ISSN 0034-6748 R&D Projects: GA ČR GA202/02/0739; GA AV ČR IAA1010315 Institutional research plan: CEZ:AV0Z1010914 Keywords : pressure cells * pressure transmitting media * CuBe * MP35N Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.226, year: 2004

Theoretical predictions for spatially-focused heating of magnetic nanoparticles guided by magnetic particle imaging field gradients

Energy Technology Data Exchange (ETDEWEB)

Dhavalikar, Rohan [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive, Gainesville, FL 32611 (United States)

2016-12-01

Magnetic nanoparticles in alternating magnetic fields (AMFs) transfer some of the field's energy to their surroundings in the form of heat, a property that has attracted significant attention for use in cancer treatment through hyperthermia and in developing magnetic drug carriers that can be actuated to release their cargo externally using magnetic fields. To date, most work in this field has focused on the use of AMFs that actuate heat release by nanoparticles over large regions, without the ability to select specific nanoparticle-loaded regions for heating while leaving other nanoparticle-loaded regions unaffected. In parallel, magnetic particle imaging (MPI) has emerged as a promising approach to image the distribution of magnetic nanoparticle tracers in vivo, with sub-millimeter spatial resolution. The underlying principle in MPI is the application of a selection magnetic field gradient, which defines a small region of low bias field, superimposed with an AMF (of lower frequency and amplitude than those normally used to actuate heating by the nanoparticles) to obtain a signal which is proportional to the concentration of particles in the region of low bias field. Here we extend previous models for estimating the energy dissipation rates of magnetic nanoparticles in uniform AMFs to provide theoretical predictions of how the selection magnetic field gradient used in MPI can be used to selectively actuate heating by magnetic nanoparticles in the low bias field region of the selection magnetic field gradient. Theoretical predictions are given for the spatial decay in energy dissipation rate under magnetic field gradients representative of those that can be achieved with current MPI technology. These results underscore the potential of combining MPI and higher amplitude/frequency actuation AMFs to achieve selective magnetic fluid hyperthermia (MFH) guided by MPI. - Highlights: • SAR predictions based on a field-dependent magnetization relaxation model. �

Magnetic and optical effects in TiO2 based dye sensitized solar cells

Science.gov (United States)

Kannan U., M.; Jammalamadaka, S. Narayana

2018-04-01

We report on the magnetic effects on the solar cell efficiency of TiO2 based dye sensitized solar cells (DSSC). The strong spin orbit coupling of rare earth Ho3+ ions introduced by the addition of Ho2O3 into the photoanode resulted in a 28% enhancement in the power conversion efficiency of DSSC. Such an enhancement in the efficiency may be attributed to the improved lifetime of photo generated excitons as a result of the accelerated intersystem crossing phenomenon. This observation is supported by our photoluminescence (PL) measurements where we could observe a decrease in the photo emission intensity with the addition of Ho2O3. In addition, we have used a low magnetic field of 100 Oe to further enhance the overall efficiency to 5.6%, which in turn proves that the Lorentz force plays a significant role in magnetic field controlled charge transport in DSSC. Finally, we have carried out a transfer matrix model based theoretical simulation for studying the optical properties of the multilayer device stack.

Automatic selection of resting-state networks with functional magnetic resonance imaging

Directory of Open Access Journals (Sweden)

Silvia Francesca eStorti

2013-05-01

Full Text Available Functional magnetic resonance imaging (fMRI during a resting-state condition can reveal the co-activation of specific brain regions in distributed networks, called resting-state networks, which are selected by independent component analysis (ICA of the fMRI data. One of the major difficulties with component analysis is the automatic selection of the ICA features related to brain activity. In this study we describe a method designed to automatically select networks of potential functional relevance, specifically, those regions known to be involved in motor function, visual processing, executive functioning, auditory processing, memory, and the default-mode network. To do this, image analysis was based on probabilistic ICA as implemented in FSL software. After decomposition, the optimal number of components was selected by applying a novel algorithm which takes into account, for each component, Pearson's median coefficient of skewness of the spatial maps generated by FSL, followed by clustering, segmentation, and spectral analysis. To evaluate the performance of the approach, we investigated the resting-state networks in 25 subjects. For each subject, three resting-state scans were obtained with a Siemens Allegra 3 T scanner (NYU data set. Comparison of the visually and the automatically identified neuronal networks showed that the algorithm had high accuracy (first scan: 95%, second scan: 95%, third scan: 93% and precision (90%, 90%, 84%. The reproducibility of the networks for visual and automatic selection was very close: it was highly consistent in each subject for the default-mode network (≥ 92% and the occipital network, which includes the medial visual cortical areas (≥ 94%, and consistent for the attention network (≥ 80%, the right and/or left lateralized frontoparietal attention networks, and the temporal-motor network (≥ 80%. The automatic selection method may be used to detect neural networks and reduce subjectivity in ICA

Magnetizable stent-grafts enable endothelial cell capture

Science.gov (United States)

Tefft, Brandon J.; Uthamaraj, Susheil; Harburn, J. Jonathan; Hlinomaz, Ota; Lerman, Amir; Dragomir-Daescu, Dan; Sandhu, Gurpreet S.

2017-04-01