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Sample records for functional magnetic microspheres

  1. Functional magnetic microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Landel, Robert F. (Inventor)

    1981-01-01

    Functional magnetic particles are formed by dissolving a mucopolysaccharide such as chitosan in acidified aqueous solution containing a mixture of ferrous chloride and ferric chloride. As the pH of the solution is raised magnetite is formed in situ in the solution by raising the pH. The dissolved chitosan is a polyelectrolyte and forms micelles surrounding the granules at pH of 8-9. The chitosan precipitates on the granules to form microspheres containing the magnetic granules. On addition of the microspheres to waste aqueous streams containing dissolved ions, the hydroxyl and amine functionality of the chitosan forms chelates binding heavy metal cations such as lead, copper, and mercury and the chelates in turn bind anions such as nitrate, fluoride, phosphate and borate.

  2. High-permeability functionalized silicone magnetic microspheres with low autofluorescence for biomedical applications

    PubMed Central

    Evans, Benjamin A.; Ronecker, Julia C.; Han, David T.; Glass, Daniel R.; Train, Tonya L.; Deatsch, Alison E.

    2017-01-01

    Functionalized magnetic microspheres are widely used for cell separations, isolation of proteins and other biomolecules, in vitro diagnostics, tissue engineering, and microscale force spectroscopy. We present here the synthesis and characterization of a silicone magnetic microsphere which can be produced in diameters ranging from 0.5 to 50 μm via emulsion polymerization of a silicone ferrofluid precursor. This bottom-up approach to synthesis ensures a uniform magnetic concentration across all sizes, leading to significant advances in magnetic force generation. We demonstrate that in a size range of 5–20 μm, these spheres supply a full order of magnitude greater magnetic force than leading commercial products. In addition, the unique silicone matrix exhibits autofluorescence two orders of magnitude lower than polystyrene microspheres. Finally, we demonstrate the ability to chemically functionalize our silicone microspheres using a standard EDC reaction, and show that our folate-functionalized silicone microspheres specifically bind to targeted HeLa and Jurkat cells. These spheres show tremendous potential for replacing magnetic polystyrene spheres in applications which require either large magnetic forces or minimal autofluorescence, since they represent order-of-magnitude improvements in each. In addition, the unique silicone matrix and proven biocompatibility suggest that they may be useful for encapsulation and targeted delivery of lipophilic pharmaceuticals. PMID:26952493

  3. High-permeability functionalized silicone magnetic microspheres with low autofluorescence for biomedical applications.

    PubMed

    Evans, Benjamin A; Ronecker, Julia C; Han, David T; Glass, Daniel R; Train, Tonya L; Deatsch, Alison E

    2016-05-01

    Functionalized magnetic microspheres are widely used for cell separations, isolation of proteins and other biomolecules, in vitro diagnostics, tissue engineering, and microscale force spectroscopy. We present here the synthesis and characterization of a silicone magnetic microsphere which can be produced in diameters ranging from 0.5 to 50 μm via emulsion polymerization of a silicone ferrofluid precursor. This bottom-up approach to synthesis ensures a uniform magnetic concentration across all sizes, leading to significant advances in magnetic force generation. We demonstrate that in a size range of 5-20 μm, these spheres supply a full order of magnitude greater magnetic force than leading commercial products. In addition, the unique silicone matrix exhibits autofluorescence two orders of magnitude lower than polystyrene microspheres. Finally, we demonstrate the ability to chemically functionalize our silicone microspheres using a standard EDC reaction, and show that our folate-functionalized silicone microspheres specifically bind to targeted HeLa and Jurkat cells. These spheres show tremendous potential for replacing magnetic polystyrene spheres in applications which require either large magnetic forces or minimal autofluorescence, since they represent order-of-magnitude improvements in each. In addition, the unique silicone matrix and proven biocompatibility suggest that they may be useful for encapsulation and targeted delivery of lipophilic pharmaceuticals.

  4. Metal containing polymeric functional microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1979-01-01

    Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing. After collection of the labeled cells, the magnetic field is discontinued and the labeled sub-cell population recovered.

  5. Functional Microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan; Margel, Shlomo

    1989-01-01

    Tiny beads develop from aqueous solution. Process forms beads of polyglutaraldehyde directly from solution. Beads of 0.5-to-1.0-micron diameter with fluorescent or magnetic properties made. Fluorescent or magnetic properties allow marked cells to be traced and identified. Useful in biology, clinical chemistry, and biochemistry.

  6. Surface functionalized magnetic PVA microspheres for rapid naked-eye recognizing of copper(II) ions in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Hua, Zulin; Yang, Bei; Chen, Wei; Bai, Xue; Xu, Quanjun; Gu, Haixin

    2014-10-01

    We proposed a robust method for surface-functionalizing magnetic polyvinyl alcohol microspheres to detect heavy metal ions in aqueous solutions. The prepared chemosensor (PAR-MPVA) was characterized through scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectra (XPS). In neutral solutions, PAR-MPVA selectively recognized diatomic heavy metal ions, as indicated with a color change from earth yellow to red; in strong acidic solutions, the chemosensor only selectively detected Cu2+. PAR-MPVA microspheres had a detection limit as low as 0.5 μM by naked-eye and 0.16 μM by UV-vis spectrometer for Cu2+. Moreover, the sensor possessed magnetism for effective recovery, could easily be regenerated by a solution of EDTA, and also displayed perferable stability. The PAR-MPVA microspheres possessed preeminent properties of detecting copper (II) ions in aqueous solutions.

  7. Preparation of uniform magnetic recoverable catalyst microspheres with hierarchically mesoporous structure by using porous polymer microsphere template

    NASA Astrophysics Data System (ADS)

    Ren, Lianbing; Teng, Chao; Zhu, Lili; He, Jie; Wang, You; Zuo, Xinbing; Hong, Mei; Wang, Yong; Jiang, Biwang; Zhao, Jing

    2014-04-01

    Merging nanoparticles with different functions into a single microsphere can exhibit profound impact on various applications. However, retaining the unique properties of each component after integration has proven to be a significant challenge. Our previous research demonstrated a facile method to incorporate magnetic nanoparticles into porous silica microspheres. Here, we report the fabrication of porous silica microspheres embedded with magnetic and gold nanoparticles as magnetic recoverable catalysts. The as-prepared multifunctional composite microspheres exhibit excellent magnetic and catalytic properties and a well-defined structure such as uniform size, high surface area, and large pore volume. As a result, the very little composite microspheres show high performance in catalytic reduction of 4-nitrophenol, special convenient magnetic separability, long life, and good reusability. The unique nanostructure makes the microspheres a novel stable and highly efficient catalyst system for various catalytic industry processes.

  8. Preparation of uniform magnetic recoverable catalyst microspheres with hierarchically mesoporous structure by using porous polymer microsphere template

    PubMed Central

    2014-01-01

    Merging nanoparticles with different functions into a single microsphere can exhibit profound impact on various applications. However, retaining the unique properties of each component after integration has proven to be a significant challenge. Our previous research demonstrated a facile method to incorporate magnetic nanoparticles into porous silica microspheres. Here, we report the fabrication of porous silica microspheres embedded with magnetic and gold nanoparticles as magnetic recoverable catalysts. The as-prepared multifunctional composite microspheres exhibit excellent magnetic and catalytic properties and a well-defined structure such as uniform size, high surface area, and large pore volume. As a result, the very little composite microspheres show high performance in catalytic reduction of 4-nitrophenol, special convenient magnetic separability, long life, and good reusability. The unique nanostructure makes the microspheres a novel stable and highly efficient catalyst system for various catalytic industry processes. PMID:24708885

  9. The affinity of magnetic microspheres for Schistosoma eggs.

    PubMed

    Candido, Renata R F; Favero, Vivian; Duke, Mary; Karl, Stephan; Gutiérrez, Lucía; Woodward, Robert C; Graeff-Teixeira, Carlos; Jones, Malcolm K; St Pierre, Timothy G

    2015-01-01

    Schistosomiasis is a chronic parasitic disease of humans, with two species primarily causing the intestinal infection: Schistosoma mansoni and Schistosoma japonicum. Traditionally, diagnosis of schistosomiasis is achieved through direct visualisation of eggs in faeces using techniques that lack the sensitivity required to detect all infections, especially in areas of low endemicity. A recently developed method termed Helmintex™ is a very sensitive technique for detection of Schistosoma eggs and exhibits 100% sensitivity at 1.3 eggs per gram of faeces, enough to detect even low-level infections. The Helminthex™ method is based on the interaction of magnetic microspheres and schistosome eggs. Further understanding the underlying egg-microsphere interactions would enable a targeted optimisation of egg-particle binding and may thus enable a significant improvement of the Helmintex™ method and diagnostic sensitivity in areas with low infection rates. We investigated the magnetic properties of S. mansoni and S. japonicum eggs and their interactions with microspheres with different magnetic properties and surface functionalization. Eggs of both species exhibited higher binding affinity to the magnetic microspheres than the non-magnetic microspheres. Binding efficiency was further enhanced if the particles were coated with streptavidin. Schistosoma japonicum eggs bound more microspheres compared with S. mansoni. However, distinct differences within eggs of each species were also observed when the distribution of the number of microspheres bound per egg was modelled with double Poisson distributions. Using this approach, both S. japonicum and S. mansoni eggs fell into two groups, one having greater affinity for magnetic microspheres than the other, indicating that not all eggs of a species exhibit the same binding affinity. Our observations suggest that interaction between the microspheres and eggs is more likely to be related to surface charge-based electrostatic

  10. Filling Porous Microspheres With Magnetic Material

    NASA Technical Reports Server (NTRS)

    Chang, Manchium; Colvin, Michael S.

    1990-01-01

    New process produces magnetic microspheres with controllable sizes, compositions, and properties for use in medical diagnostic tests, biological research, and chemical processes. Paramagnetic microspheres also made with process. Porous plastic microspheres prepared by polymerization of monomer in diluent by cross-linking agent. When diluent removed, it leaves tiny pores throughout polymerized spheres. Size and distribution of pores determined by amount and type of diluent and cross-linking agent.

  11. Highly selective removal of Hg2+ and Pb2+ by thiol-functionalized Fe3O4@metal-organic framework core-shell magnetic microspheres

    NASA Astrophysics Data System (ADS)

    Ke, Fei; Jiang, Jing; Li, Yizhi; Liang, Jing; Wan, Xiaochun; Ko, Sanghoon

    2017-08-01

    In this work, we report a novel type of thiol-functionalized magnetic core-shell metal-organic framework (MOF) microspheres that can be potentially used for selective removal of Hg2+ and Pb2+ in the presence of other background ions from wastewater. The monodisperse Fe3O4@Cu3(btc)2 core-shell magnetic microspheres have been fabricated by a versatile step-by-step assembly strategy. Further, the thiol-functionalized Fe3O4@Cu3(btc)2 magnetic microspheres were successfully synthesized by utilizing a facile postsynthetic strategy. Significantly, the thiol-functionalized Fe3O4@Cu3(btc)2 magnetic microspheres exhibit remarkably selective adsorption affinity for Hg2+ (Kd = 5.98 × 104 mL g-1) and Pb2+ (Kd = 1.23 × 104 mL g-1), while a weaker binding affinity occurred for the other background ions such as Ni2+, Na+, Mg2+, Ca2+, Zn2+ and Cd2+. The adsorption kinetics follow the pseudo-second-order rate equation and with an almost complete removal of Hg2+ and Pb2+ from the mixed heavy metal ions wastewater (0.5 mM) within 120 min. Moreover, this adsorbent can be easily recycled because of the presence of the magnetic Fe3O4 core. This work provides a promising functionalized porous magnetic Fe3O4@MOF-based adsorbent with easy recycling property for the selective removal of heavy metal ions from wastewater.

  12. Preparation of C₁₈-functionalized magnetic polydopamine microspheres for the enrichment and analysis of alkylphenols in water samples.

    PubMed

    Wang, Xianying; Deng, Chunhui

    2016-02-01

    In this work, C18-functionalized magnetic polydopamine microspheres (Fe3O4@PDA@C18) were successfully synthesized and applied to the analysis of alkylphenols in water samples. The magnetic Fe3O4 particles coated with hydrophilic surface were synthesized via a solvothermal reaction and the self-polymerization of dopamine. And then the C18 groups were fabricated by a silylanization method. Benefit from the merits of Fe3O4 particles, polydopamine coating and C18 groups, the Fe3O4@PDA@C18 material possessed several properties of super magnetic responsiviness, good water dispersibility, π-electron system and hydrophobic C18 groups. Thus, the materials had great potential to be developed as the adsorbent for the magnetic solid-phase extraction (MSPE) technique. Here, we selected three kinds of alkylphenols (4-tert-octylphenol, 4-n-nonylphenol, 4-n-octylphenol) to be the target analyst for evaluating the performance of the prepared material. In this study, various extraction parameters were investigated and optimized, such as pH values of water sample solution, amount of adsorbents, adsorption and desorption time, the species of desorption solution. Meanwhile, the method validations were studied, including linearity, limit of detection and method precision. From the results, Fe3O4@PDA@C18 composites were successfully applied as the adsorbents for the extraction of alkylphenols in water samples. The proposed material provided an approach for a simple, rapid magnetic solid-phase extraction for hydrophobic compounds in environmental samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Selective enrichment of metal-binding proteins based on magnetic core/shell microspheres functionalized with metal cations.

    PubMed

    Fang, Caiyun; Zhang, Lei; Zhang, Xiaoqin; Lu, Haojie

    2015-06-21

    Metal binding proteins play many important roles in a broad range of biological processes. Characterization of metal binding proteins is important for understanding their structure and biological functions, thus leading to a clear understanding of metal associated diseases. The present study is the first to investigate the effectiveness of magnetic microspheres functionalized with metal cations (Ca(2+), Cu(2+), Zn(2+) and Fe(3+)) as the absorbent matrix in IMAC technology to enrich metal containing/binding proteins. The putative metal binding proteins in rat liver were then globally characterized by using this strategy which is very easy to handle and can capture a number of metal binding proteins effectively. In total, 185 putative metal binding proteins were identified from rat liver including some known less abundant and membrane-bound metal binding proteins such as Plcg1, Acsl5, etc. The identified proteins are involved in many important processes including binding, catalytic activity, translation elongation factor activity, electron carrier activity, and so on.

  14. Identification of target proteins of mangiferin in mice with acute lung injury using functionalized magnetic microspheres based on click chemistry.

    PubMed

    Wang, Jiajia; Nie, Yan; Li, Yunjuan; Hou, Yuanyuan; Zhao, Wei; Deng, Jiagang; Wang, Peng George; Bai, Gang

    2015-11-18

    Prevention of the occurrence and development of inflammation is a vital therapeutic strategy for treating acute lung injury (ALI). Increasing evidence has shown that a wealth of ingredients from natural foods and plants have potential anti-inflammatory activity. In the present study, mangiferin, a natural C-glucosyl xanthone that is primarily obtained from the peels and kernels of mango fruits and the bark of the Mangifera indica L. tree, alleviated the inflammatory responses in lipopolysaccharide (LPS)-induced ALI mice. Mangiferin-modified magnetic microspheres (MMs) were developed on the basis of click chemistry to capture the target proteins of mangiferin. Mass spectrometry and molecular docking identified 70 kDa heat-shock protein 5 (Hspa5) and tyrosine 3-monooxygenase (Ywhae) as mangiferin-binding proteins. Furthermore, an enzyme-linked immunosorbent assay (ELISA) indicated that mangiferin exerted its anti-inflammatory effect by binding Hspa5 and Ywhae to suppress downstream mitogen-activated protein kinase (MAPK) signaling pathways. Thoroughly revealing the mechanism and function of mangiferin will contribute to the development and utilization of agricultural resources from M. indica L.

  15. Magnetic microsphere-based mixers for microdroplets

    NASA Astrophysics Data System (ADS)

    Roy, Tamal; Sinha, Ashok; Chakraborty, Sayan; Ganguly, Ranjan; Puri, Ishwar K.

    2009-02-01

    While droplet-based microfluidic systems have several advantages over traditional flow-through devices, achieving adequate mixing between reagents inside droplet-based reactors remains challenging. We describe an active mixing approach based on the magnetic stirring of self-assembled chains of magnetic microspheres within the droplet as these stirrers experience a rotating magnetic field. We measure the mixing of a water-soluble dye in the droplet in terms of a dimensional mixing parameter as the field-rpm, fluid viscosity, and microsphere loading are parametrically varied. These show that the mixing rate has a maximum value at a critical Mason number that depends upon the operating conditions.

  16. Preparation and characterization of magnetic P(St-co-MAA-co-AM) microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Z. L.; Yang, X. B.; Yao, K. L.; Du, G. H.; Liu, Z. S.

    2006-07-01

    In this study, magnetic polymer-coated microspheres were prepared by the microemulsion polymerization of styrene (St), methacrylic acid (MAA), acryamide (AM) in the presence of emulsifiers with the size of 1-5 μm. The magnetic material (i.e. Fe 3O 4) coated with oleic acid used in the preparation of the microspheres was synthesized in a classical co-precipitation procedure. The morphological and magnetic properties of the microspheres were investigated by different techniques (i.e. TEM, TGA, optical microscopy, vibrating sample magnetometer). The results indicated that the magnetic microspheres were superparamagnetic, well shaped spheres, mono-dispersed with abundant functional groups on the surfaces of the magnetic microspheres and good thermal stability. The microspheres could be linked well with the avidin and FITC antibody.

  17. Double-walled hollow polymeric microspheres with independent pH and temperature dual-responsive and magnetic-targeting function from onion-shaped core-shell structures.

    PubMed

    Du, Pengcheng; Wang, Tingmei; Liu, Peng

    2013-02-01

    The magnetic-targeting stimuli-responsive hollow polymeric microspheres show unique performance as the intelligent carriers for the site specific controlled delivery of drugs or genes. In the work, the well-defied dual-responsive double-walled hollow microspheres with movable magnetic cores were prepared from the penta-layer onion-shaped core-shell microspheres. Their double-walled shells were independent, with the pH-responsive crosslinked poly(methacrylic acid) (PMAA) layer as the inner shell and the temperature responsive crosslinked poly(N-isopropylacrylamide) (PNIPAM) layer as the outer shell. The combination of the pH and temperature dual-responsive and the magnetic-targeting function make the hollow microspheres to be the most promising intelligent carriers in the biomedical fields. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. High Throughput Enzyme Inhibitor Screening by Functionalized Magnetic Carbonaceous Microspheres and Graphene Oxide-Based MALDI-TOF-MS

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Li, Yan; Liu, Junyan; Deng, Chunhui; Zhang, Xiangmin

    2011-12-01

    In this work, a high throughput methodology for screening enzyme inhibitors has been demonstrated by combining enzyme immobilized magnetic carbonaceous microspheres and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with grapheme oxide as matrix. First, model enzyme acetylcholinesterase (AChE) was immobilized onto the 3-glycidoxypropyltrimethoxysilane (GLYMO)-modified magnetic carbonaceous (MC) microspheres, displaying a high enzyme activity and stability, and also facilitating the separation of enzyme from substrate and product. The efficiency of immobilized AChE was monitored by biochemical assay, which was carried out by mixing enzyme-immobilized MC microspheres with model substrate acetylcholine (ACh), and subsequent quantitative determination of substrate ACh and product choline using graphene oxide-based MALDI-TOF-MS with no background inference. The limit of detection (LOD) for ACh was 0.25 fmol/μL, and excellent linearity (R2 = 0.9998) was maintained over the range of 0.5 and 250 fmol/μL. Choline was quantified over the range of 0.05 and 15 pmol/μL, also with excellent linearity (R2 = 0.9994) and low LOD (0.15 fmol/μL). Good accuracy and precision were obtained for all concentrations within the range of the standard curves. All together, eight compounds (four known AChE inhibitors and four control chemical compounds with no AChE inhibit effect) were tested with our promoted methodology, and the obtained results demonstrated that our high throughput screening methodology could be a great help to the routine enzyme inhibitor screening.

  19. Amino-functionalized core-shell magnetic mesoporous composite microspheres for Pb(II) and Cd(II) removal.

    PubMed

    Tang, Yulin; Liang, Song; Wang, Juntao; Yu, Shuili; Wang, Yilong

    2013-04-01

    Amino-functionalized Fe3O4@mesoporous SiO2 core-shell composite microspheres NH2-MS in created in multiple synthesis steps have been investigated for Pb(II) and Cd(II) adsorption. The microspheres were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), N2 adsorption-desorption, zeta potential measurements and vibrating sample magnetometer. Batch adsorption tests indicated that NH2-MS exhibited higher adsorption affinity toward Pb(II) and Cd(II) than MS did. The Langmuir model could fit the adsorption isotherm very well with maximum adsorption capacity of 128.21 and 51.81 mg/g for Pb(II) and Cd(II), respectively, implying that adsorption processes involved monolayer adsorption. Pb(II) and Cd(II) adsorption could be well described by the pseudo second-order kinetics model, and was found to be strongly dependent on pH and humic acid. The Pb(II)- and Cd(II)-loaded microspheres were effectively desorbed using 0.01 mol/L HCl or EDTA solution. NH2-MS have promise for use as adsorbents in the removal of Pb(II) and Cd(II) in wastewater treatment processes.

  20. Facile preparation of hexadecyl-functionalized magnetic core-shell microsphere for the extraction of polychlorinated biphenyls in environmental waters.

    PubMed

    Fan, Yu-Han; Zhang, Shou-Wen; Qin, Shi-Bin; Li, Xiao-Shui; Zhang, Yuan; Qi, Shi-Hua

    2017-03-10

    Alkyl moieties which can retain target analytes due to their lipophilicity are important in sample preparation. In this work, hexadecyl-functionalized magnetic core-shell microspheres (Fe3O4@SiO2-C16) was successfully prepared by one-pot sol-gel method and used for magnetic solid-phase extraction of polychlorinated biphenyls (PCBs) in environmental water samples. Optimized preparation method was achieved by altering the adding moment of hexadecyl-silane. The resultant materials were systematically characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, tensionmeter, and vibrating sample magnetometer. The results demonstrated that the optimized adsorbent exhibited core-shell structure, superparamagnetic (66 emu/g), and extremely hydrophobic (water contact angle of 122°) properties. To evaluate the extraction performance, the prepared material coupled with gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was applied to determinate PCBs. The extraction conditions were optimized. Under the optimal conditions, the proposed method showed a good linearity range of 1-100 ng L(-1) with correlation coefficients (R) of 0.9989-0.9993. Based on a signal-to-noise ratio of 3 and 10, the limits of detection (LODs) and limits of quantification (LOQs) were in the range 0.14-0.27 and 0.39-0.91 ng L(-1), respectively. The intra- and inter-day relative standard deviations (RSDs) were less than 9.06%. The absolute recoveries of PCBs in spiked real water samples were in the range of 75.17 to 101.20%. Additionally, reusability and batch-to-batch reproducibility of the resultant material were acceptable with RSDs less than 5.64 and 3.25%, respectively. Graphical Abstract The synthesis procedure of Fe3O4@SiO2-C16 and determination of PCBs in water sample 129 × 50 mm (300 × 300 DPI).

  1. Preparation of phenyl group-functionalized magnetic mesoporous silica microspheres for fast extraction and analysis of acetaldehyde in mainstream cigarette smoke by gas chromatography-mass spectrometry.

    PubMed

    Huang, Danni; Sha, Yunfei; Zheng, Saijing; Liu, Baizhan; Deng, Chunhui

    2013-10-15

    Acetaldehyde is regarded as a toxic mainstream cigarette smoke constituent, and measurement of acetaldehyde in complex real samples is difficult owing to its high volatility and reactivity. In this work, phenyl group-functionalized magnetic mesoporous microspheres were developed as the solid-phase extraction sorbents for enrichment and analysis of acetaldehyde in mainstream cigarette smoke. The functional magnetic microspheres were first synthesized through a facile one-pot co-condensation approach. The prepared nanomaterials possessed abundant silanol groups in the exterior surface and numerous phenyl groups in the interior pore-walls, as well as a large surface area (273.5m(2)/g), strong superparamagnetism and uniform mesopores (3.3 nm). Acetaldehyde in mainstream cigarette smoke was collected in water and derivatizated with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine. The formed acetaldehyde oximes were extracted and enriched by the prepared adsorbents via π-π interactions and subsequently analyzed using GC-MS. Extraction conditions such as amounts of sorbents, eluting solvent, adsorption and desorption time were investigated and optimized to achieve the best efficiency. Method validations including linearity, recovery, repeatability, and limit of detection were also studied. It was found that the suggested methodology provided low detection limit of 0.04 mg/mL, good recovery of 88-92%, intra-day and inter-day RSD values of 4.5% and 10.1%, and linear range of 0.25-4 mg/mL (R(2)=0.999). The results indicated that the proposed method based on phenyl-functionalized magnetic mesoporous microspheres was rapid, efficient and convenient for the enrichment and analysis of acetaldehyde in tobacco.

  2. Synthesis and studies of trisubstituted biphthalonitrile/Fe3O4 magnetic hybrid microspheres

    NASA Astrophysics Data System (ADS)

    Kamzin, A. S.; Liu, X. B.

    2016-10-01

    New trisubstituted biphthalonitrile/magnetite (TSB/Fe3O4) magnetic hybrid microspheres were synthesized from TSB and FeCl3 · 6H2O using the method of one-stage thermal temperature crystallization of solvents. The morphology and structure of magnetic hybrid microspheres were inspected using a scanning electron microscope, IR Fourier spectroscopy, and X-ray diffraction. It was found that the grown TSB/Fe3O4 magnetic hybrid microspheres represent spherical particles with an average size of 137 nm and a small size spread. The size and size distribution of magnetic hybrid microspheres can be controlled by a small change in the ratio of TSB and Fe3+ ion contents in the microsphere. TSB/Fe3O4 hybrid microspheres exhibit a rather high saturation magnetization (58.16 emu g-1) and new microwave electromagnetic properties, i.e., lower (in comparison with published) dielectric losses at low frequencies; magnetic losses are increased obviously due to an increase in the TSB content. Furthermore, it is detected that magnetic hybrid microspheres absorb microwaves, and strong reflection losses in a wide frequency range are established. The effective reflection loss of-31 dB is obtained in the microwave range from 2 to 16 GHz due to TSB content variations. Wide absorption properties of microwaves along with regular spherical shape and excellent magnetic properties offer wide opportunities for various applications of TSB/Fe3O4 magnetic hybrid microspheres as functional materials.

  3. Biocompatible magnetic microspheres for Use in PDT and hyperthermia.

    PubMed

    Vaccari, C B; Cerize, N N P; Morais, P C; Ré, M I; Tedesco, A C

    2012-06-01

    Loaded microspheres with a silicon (IV) phthalocyanine derivative (NzPC) acting as a photosensitizer were prepared from polyhydroxybutyrate-co-valerate (PHBHV) and poly(ecaprolactone) (PCL) polymers using the emulsification solvent evaporation method (EE). The aim of our study was to prepare two systems of these biodegradable PHBHV/PCL microspheres. The first one containing only photosensitizer previously incorporated in the PHBHV and poly(ecaprolactone) (PCL) microspheres and the second one with the post magnetization of the DDS with magnetic nanoparticles. Magnetic fluid is successfully used for controlled incorporation of nanosized magnetic particles within the micron-sized template. This is the first time that we could get a successful pos incorporation of nanosized magnetic particles in a previously-prepared polymeric template. This procedure opens a great number of possibilities of post-functionalization of polymeric micro or nanoparticles with different bioactive materials. The NzPC release profile of the systems is ideal for PDT, the zeta potential and the size particle are stable upon aging in time. In vitro studies were evaluated using gingival fibroblastic cell line. The dark citotoxicity, the phototoxicity and the AC magnetic field assays of the as-prepared nanomagnetic composite were evaluated and the cellular viability analyzed by the classical test of MTT.

  4. Magnetic Microspheres for Therapeutical Applications

    NASA Technical Reports Server (NTRS)

    Mazuruk, K.; Ramachandran, N.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Hyperthermia is a well known cancer therapy and consists of heating a tumor region to the elevated temperatures in the range of 40-45 C for an extended period of time (2-8 hours). This leads to thermal inactivation of cell regulatory and growth processes with resulting widespread necrosis, carbonization and coagulation. Moreover, heat boosts the tumor response to other treatments such as radiation, chemotherapy or immunotherapy. Of particular importance is careful control of generated heat in the treated region and keeping it localized. Higher heating, to about 56 C can lead to tissue thermo-ablation. With accurate temperature control, hyperthermia has the advantage of having minimal side effects. Several heating techniques are utilized for this purpose, such as whole body hyperthermia, radio-frequency (RF) hyperthermia, ultrasound technique, inductive microwave antenna hyperthermia, inductive needles (thermoseeds), and magnetic fluid hyperthermia (MFH).MFH offers many advantages as targeting capability by applying magnets. However, this technology still suffers significant inefficiencies due to lack of thermal control. This paper will provide a review of the topic and outline the ongoing work in this area. The main emphasis is in devising ways to overcome the technical difficulty in hyperthermia therapy of achieving a uniform therapeutic temperature over the required region of the body and holding it steady. The basic obstacle of the present heating methods are non-uniform thermal properties of the tissue. Our approach is to develop a novel class of magnetic fluids which have inherent thermoregulating properties. We have identified a few magnetic alloys which can serve as a suitable nano-particle material. The objective is to synthesize, characterize and evaluate the efficacy of TRMF for hyperthermia therapy.

  5. Magnetic Microspheres for Therapeutical Applications

    NASA Technical Reports Server (NTRS)

    Mazuruk, K.; Ramachandran, N.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Hyperthermia is a well known cancer therapy and consists of heating a tumor region to the elevated temperatures in the range of 40-45 C for an extended period of time (2-8 hours). This leads to thermal inactivation of cell regulatory and growth processes with resulting widespread necrosis, carbonization and coagulation. Moreover, heat boosts the tumor response to other treatments such as radiation, chemotherapy or immunotherapy. Of particular importance is careful control of generated heat in the treated region and keeping it localized. Higher heating, to about 56 C can lead to tissue thermo-ablation. With accurate temperature control, hyperthermia has the advantage of having minimal side effects. Several heating techniques are utilized for this purpose, such as whole body hyperthermia, radio-frequency (RF) hyperthermia, ultrasound technique, inductive microwave antenna hyperthermia, inductive needles (thermoseeds), and magnetic fluid hyperthermia (MFH).MFH offers many advantages as targeting capability by applying magnets. However, this technology still suffers significant inefficiencies due to lack of thermal control. This paper will provide a review of the topic and outline the ongoing work in this area. The main emphasis is in devising ways to overcome the technical difficulty in hyperthermia therapy of achieving a uniform therapeutic temperature over the required region of the body and holding it steady. The basic obstacle of the present heating methods are non-uniform thermal properties of the tissue. Our approach is to develop a novel class of magnetic fluids which have inherent thermoregulating properties. We have identified a few magnetic alloys which can serve as a suitable nano-particle material. The objective is to synthesize, characterize and evaluate the efficacy of TRMF for hyperthermia therapy.

  6. Nano-functionalization of protein microspheres

    NASA Astrophysics Data System (ADS)

    Yoon, Sungkwon; Nichols, William T.

    2014-08-01

    Protein microspheres are promising building blocks for the assembly of complex functional materials. Here we demonstrate a set of three techniques that add functionality to the surface of protein microspheres. In the first technique, a positive surface charge on the protein spheres is deposited by electrostatic adsorption. Negatively charged silica and gold nanoparticle colloids can then electrostatically bind reversibly to the microsphere surface. In the second technique, nanoparticles are covalently anchored to the protein shell using a simple one-pot process. The strong covalent bond between sulfur groups in cysteine in the protein shell irreversibly binds to the gold nanoparticles. In the third technique, surface morphology of the protein microsphere is tuned through hydrodynamic instability at the water-oil interface. This is accomplished through the degree of solubility of the oil phase in water. Taken together these three techniques form a platform to create nano-functionalized protein microspheres, which can then be used as building blocks for the assembly of more complex macroscopic materials.

  7. Method of detecting luminescent target ions with modified magnetic microspheres

    DOEpatents

    Shkrob, Ilya A; Kaminski, Michael D

    2014-05-13

    This invention provides methods of using modified magnetic microspheres to extract target ions from a sample in order to detect their presence in a microfluidic environment. In one or more embodiments, the microspheres are modified with molecules on the surface that allow the target ions in the sample to form complexes with specific ligand molecules on the microsphere surface. In one or more embodiments, the microspheres are modified with molecules that sequester the target ions from the sample, but specific ligand molecules in solution subsequently re-extract the target ions from the microspheres into the solution, where the complexes form independent of the microsphere surface. Once the complexes form, they are exposed to an excitation wavelength light source suitable for exciting the target ion to emit a luminescent signal pattern. Detection of the luminescent signal pattern allows for determination of the presence of the target ions in the sample.

  8. A novel approach to preparing magnetic protein microspheres with core-shell structure

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; Sun, Zhendong; Li, Fengsheng; Chen, Kai; Liu, Tianyu; Liu, Jialing; Zhou, Tianle; Guo, Rui

    2011-03-01

    Magnetic protein microspheres with core-shell structure were prepared through a novel approach based on the sonochemical method and the emulsion solvent evaporation method. The microspheres are composed of the oleic acid and undecylenic acid modified Fe 3O 4 cores and coated with globular bovine serum albumin (BSA). Under an optimized condition, up to 57.8 wt% of approximately 10 nm superparamagnetic Fe 3O 4 nanoparticles could be uniformly encapsulated into the BSA microspheres with the diameter of approximately 160 nm and the high saturation magnetization of 38.5 emu/g, besides of the abundant functional groups. The possible formation mechanism of magnetic microspheres was discussed in detail.

  9. T2-Shortening of 3He Gas by Magnetic Microspheres

    SciTech Connect

    Minard, Kevin R; Timchalk, Chuck; Corley, Rick A

    2005-03-01

    In the interconnected pores of a material like the lung the transverse relaxation time (T2) for 3He gas is shortened by the deposition of magnetic microspheres and rapid molecular diffusion through induced field distortions. Here, this unique relaxation process is described theoretically and predicted T2-shortening is validated using pressurized 3He gas in a foam model of lung tissue. Results demonstrate that – 1) significant T2-shortening is induced by microsphere deposition, 2) shortened T2’s are accurately predicted, and 3) measured relaxation times are exploitable for quantifying the local volume fraction of magnetic microspheres deposited in gas-filled spaces.

  10. Engineered magnetic core-shell SiO2/Fe microspheres and "medusa-like" microspheres of SiO2/iron oxide/carbon nanofibers or nanotubes.

    PubMed

    Mero, On; Sougrati, Moulay-Tahar; Jumas, Jean-Claude; Margel, Shlomo

    2014-08-19

    Iron oxide (IO) thin coatings of controlled thickness on SiO2 microspheres of narrow size distribution were prepared by decomposition at 160 °C of triiron dodecacarbonyl onto silica microspheres dispersed in diethylene glycol diethyl ether free of surfactant or stabilizer. The dried washed SiO2/IO core-shell microspheres were annealed at different temperatures and time periods under inert (Ar) or reducing (H2) atmosphere. The effect of temperature on the chemical composition, morphology, crystallinity, and magnetic properties of the IO and the elemental Fe nanoparticles type coatings onto the SiO2 core microspheres has been elucidated. "Medusa-like" SiO2/IO/carbon nanofibers and tubes particles were prepared by CVD of ethylene on the surface of the SiO2/IO microspheres at different temperatures. The morphology change of the grafted carbon nanofibers and tubes as a function of the CVD temperature was also elucidated.

  11. Biocompatible magnetic and molecular dual-targeting polyelectrolyte hybrid hollow microspheres for controlled drug release.

    PubMed

    Du, Pengcheng; Zeng, Jin; Mu, Bin; Liu, Peng

    2013-05-06

    Well-defined biocompatible magnetic and molecular dual-targeting polyelectrolyte hybrid hollow microspheres have been accomplished via the layer-by-layer (LbL) self-assembly technique. The hybrid shell was fabricated by the electrostatic interaction between the polyelectrolyte cation, chitosan (CS), and the hybrid anion, citrate modified ferroferric oxide nanoparticles (Fe3O4-CA), onto the uniform polystyrene sulfonate microsphere templates. Then the magnetic hybrid core/shell composite particles were modified with a linear, functional poly(ethylene glycol) (PEG) monoterminated with a biotargeting molecule (folic acid (FA)). Afterward the dual targeting hybrid hollow microspheres were obtained after etching the templates by dialysis. The dual targeting hybrid hollow microspheres exhibit exciting pH response and stability in high salt-concentration media. Their pH-dependent controlled release of the drug molecule (anticancer drug, doxorubicin (DOX)) was also investigated in different human body fluids. As expected, the cell viability of the HepG2 cells which decreased more rapidly was treated by the FA modified hybrid hollow microspheres rather than the unmodified one in the in vitro study. The dual-targeting hybrid hollow microspheres demonstrate selective killing of the tumor cells. The precise magnetic and molecular targeting properties and pH-dependent controlled release offers promise for cancer treatment.

  12. Alginate-based ferrofluid and magnetic microsphere thereof.

    PubMed

    Xu, Peihu; Guo, Fengfeng; Huang, Jin; Zhou, Shaofeng; Wang, Daxin; Yu, Jiahui; Chen, Jinghua

    2010-12-01

    The Fe(3)O(4) ferrofluids have been prepared using sodium alginate (Na-AL) as a stabilizing agent. The alginate can prevent the aggregation of magnetic nanoparticles and hence contributed to higher stability for the ferrofluids. Furthermore, the alginate component in the ferrofluids was crosslinked by Ca(2+) to produce magnetic microspheres. The swelling behavior of magnetic microspheres showed a pH-dependence, and hence determined the drug release process under various pH conditions. The presence of the Fe(3)O(4) nanoparticles made the magnetic microspheres swell more easily. Meanwhile, the strong ability to absorb the drug for the incorporated Fe(3)O(4) nanoparticles decreased the release rate and hence was more favorable to the sustaining release of drug. Except for the controlled delivery and release of drug, the alginate-based ferrofluids and magnetic microspheres in this work might also show a great potential for other biomedical and biotechnological applications, such as, magnetic targeting, magnetic separation and magnetic resonance imaging.

  13. Assembly of functional gold nanoparticle on silica microsphere.

    PubMed

    Wang, Hsuan-Lan; Lee, Fu-Cheng; Tang, Tse-Yu; Zhou, Chenguang; Tsai, De-Hao

    2016-05-01

    We demonstrate a controlled synthesis of silica microsphere with the surface-decorated functional gold nanoparticles. Surface of silica microsphere was modified by 3-aminopropypltriethoxysilane and 3-aminopropyldimethylethoxysilane to generate a positive electric field, by which the gold nanoparticles with the negative charges (unconjugated, thiolated polyethylene glycol functionalized with the traceable packing density and conformation) were able to be attracted to the silica microsphere. Results show that both the molecular conjugation on gold nanoparticle and the uniformity in the amino-silanization of silica microsphere influenced the loading and the homogeneity of gold nanoparticles on silica microsphere. The 3-aminopropyldimethylethoxysilane-functionalized silica microsphere provided an uniform field to attract gold nanoparticles. Increasing the ethanol content in aminosilane solution significantly improved the homogeneity and the loading of gold nanoparticles on the surface of silica microsphere. For the gold nanoparticle, increasing the molecular mass of polyethylene glycol yielded a greater homogeneity but a lower loading on silica microsphere. Bovine serum albumin induced the desorption of gold nanoparticles from silica microsphere, where the extent of desorption was suppressed by the presence of high-molecular mass polyethylene glycol on gold nanoparticles. This work provides the fundamental understanding for the synthesis of gold nanoparticle-silica microsphere constructs useful to the applications in chemo-radioactive therapeutics.

  14. On-demand one-step synthesis of monodisperse functional polymeric microspheres with droplet microfluidics.

    PubMed

    Yu, Xu; Cheng, Gong; Zhou, Ming-Da; Zheng, Si-Yang

    2015-04-07

    A simple and robust method for one-step synthesis of monodisperse functional polymeric microspheres was established by generation of reversed microemulsion droplets in aqueous phase inside microfluidic chips and controlled evaporation of the organic solvent. Using this method, water-soluble nanomaterials can be easily encapsulated into biodegradable Poly(D,L-lactic-co-glycolic acid) (PLGA) to form functional microspheres. By controlling the flow rate of microemulsion phase, PLGA polymeric microspheres with narrow size distribution and diameters in the range of ∼50-100 μm were obtained. As a demonstration of the versatility of the approach, high-quality fluorescent CdTe:Zn(2+) quantum dots (QDs) of various emission spectra, superparamagnetic Fe3O4 nanoparticles, and water-soluble carbon nanotubes (CNTs) were used to synthesize fluorescent PLGA@QDs, magnetic PLGA@Fe3O4, and PLGA@CNTs polymeric microspheres, respectively. In order to show specific applications, the PLGA@Fe3O4 were modified with polydopamine (PDA), and then the silver nanoparticles grew on the surfaces of the PLGA@Fe3O4@PDA polymeric microspheres by reducting the Ag(+) to Ag(0). The as-prepared PLGA@Fe3O4@PDA-Ag microspheres showed a highly efficient catalytic reduction of the 4-nitrophenol, a highly toxic substance. The monodisperse uniform functional PLGA polymeric microspheres can potentially be critically important for multiple biomedical applications.

  15. Bulk magnetic terahertz metamaterials based on dielectric microspheres.

    PubMed

    Šindler, M; Kadlec, C; Dominec, F; Kužel, P; Elissalde, C; Kassas, A; Lesseur, J; Bernard, D; Mounaix, P; Němec, H

    2016-08-08

    Rigid metamaterials were prepared by embedding TiO2 microspheres into polyethylene. These structures exhibit a series of Mie resonances where the lowest-frequency one is associated with a strong dispersion in the effective magnetic permeability. Using time-domain terahertz spectroscopy, we experimentally demonstrated the magnetic nature of the observed resonance. The presented approach shows a way for low-cost massive fabrication of mechanically stable terahertz metamaterials based on dielectric microresonators.

  16. Bioassay and biomolecular identification, sorting, and collection methods using magnetic microspheres

    DOEpatents

    Kraus, Jr., Robert H.; Zhou, Feng; Nolan, John P

    2007-06-19

    The present invention is directed to processes of separating, analyzing and/or collecting selected species within a target sample by use of magnetic microspheres including magnetic particles, the magnetic microspheres adapted for attachment to a receptor agent that can subsequently bind to selected species within the target sample. The magnetic microspheres can be sorted into a number of distinct populations, each population with a specific range of magnetic moments and different receptor agents can be attached to each distinct population of magnetic microsphere.

  17. Synthesis of monodisperse, hierarchically mesoporous, silica microspheres embedded with magnetic nanoparticles.

    PubMed

    Wang, Yong; He, Jie; Chen, Jiwei; Ren, Lianbing; Jiang, Biwang; Zhao, Jing

    2012-05-01

    We report a preparation method for the synthesis of monodisperse magnetic polymer/silica hybrid microspheres using polymer microspheres incorporated with magnetic nanoparticles as a novel template. Monodisperse, hierarchically mesoporous, silica microspheres embedded with magnetic nanoparticles were successfully fabricated after the calcination of the hybrid microspheres. The magnetic nanoparticles were encapsulated in silica and distributed over the whole area of the porous microspheres without leakage. The resulting inorganic materials possess highly useful properties such as high magnetic nanoparticle loading, high surface area, and large pore volumes. The hierarchically mesoporous magnetic silica microspheres resulted in a high bovine serum albumin (BSA) protein adsorption capacity (260 mg/g) and a fast adsorption rate (reaching equilibrium with 8 h).

  18. Ultrafast hydrothermal synthesis of high quality magnetic core phenol-formaldehyde shell composite microspheres using the microwave method.

    PubMed

    You, Li-Jun; Xu, Shuai; Ma, Wan-Fu; Li, Dian; Zhang, Yu-Ting; Guo, Jia; Hu, Jack J; Wang, Chang-Chun

    2012-07-17

    An ultrafast, facile, and efficient microwave hydrothermal approach was designed to fabricate magnetic Fe(3)O(4)/phenol-formaldehyde (PF) core-shell microspheres for the first time. The structure of the Fe(3)O(4)/PF core-shell microspheres could be well controlled by the in situ polycondensation of phenol and formaldehyde with magnetic Fe(3)O(4) clusters as the seeds in an aqueous solution without any surfactants. The effect of synthetic parameters, such as the feeding amounts of phenol, the dosages of formaldehyde, the reaction temperatures, and the microwave heating time, on the morphologies and sizes of the Fe(3)O(4)/PF microspheres were investigated in details. The phenol-formaldehyde shell is found to be evenly coated on Fe(3)O(4) clusters within 10 min of the irradiation. The as-prepared microspheres were highly uniform in morphology, and the method was found to allow the shell thickness to be finely controlled in the range of 10-200 nm. The properties of the composite microspheres were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetic analysis (TGA), Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The as-prepared Fe(3)O(4)/PF microspheres were monodisperse and highly dispersible in water, ethanol, N,N-dimethyformamide, and acetone, a beneficial quality for the further functionalization and applications of the Fe(3)O(4)/PF microspheres.

  19. Magnetically responsive phase-change microspheres with large magnetization using ferrite nanoparticles.

    PubMed

    Du, Yufan; Wang, Yongsheng; He, Dawei; Feng, Bin; Ju, Changbin; Zhao, Huan; Fu, Ming

    2010-03-01

    Magnetically responsive phase-change microspheres were prepared and studied in this article. In the synthetic process, oleic acid was used to modify the iron oxide nanoparticles. The ferrite nanoparticles, about 10 nm in diameter, were highly dispersed due to the oleic acid on the surface of the particles, and they were encapsulated in polymethyl methacrylate (PMMA) by microemulsion polymerization with paraffin, which could be presumed from the differential scanning calorimetry (DSC) curves. According to the morphology in the scanning electron microscopy (SEM) image, the average diameter of the microspheres was about 200 nm, a large amount of nano-sized ferrite can be observed in a transmission electron microscope (TEM) image showing the structure of the microspheres. Finally, in the magnetization curve from a vibrating sample magnetometer, the saturation magnetization of microspheres was 12.2 emu/g, which was effective in the compatibility of infrared simulation and microwave absorption.

  20. Synthesis of Magnetic Microspheres with Sodium Alginate and Activated Carbon for Removal of Methylene Blue

    PubMed Central

    Li, Chaodao; Lu, Jianjiang; Li, Shanman; Tong, Yanbin; Ye, Bangce

    2017-01-01

    Based on the adsorption performance of composite microspheres with activated carbon (AC) and sodium alginate (SA), as well as the magnetic property of Fe3O4, we designed and explored an efficient strategy to prepare a unique, multifunctional Fe3O4/AC/SA composite absorbent (MSA-AC) that extracted dye from aqueous solution. The composite exhibited the following advantages: rapid and simple to prepare, environmentally friendly process, low-cost, recyclability, and multi-functionality. The physicochemical properties of the prepared magnetic microspheres were measured, and methylene blue (MB) was selected to investigate the performance of the magnetic absorbent. The results showed a maximum adsorption capacity of 222.3 mg/g for MB. Adsorption studies revealed that the data of adsorption isotherms and kinetics fit the pseudo-second-order kinetic model and Langmuir isotherm model. PMID:28772443

  1. Magnetic protein microspheres as dynamic contrast agents for magnetomotive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Nguyen, Freddy T.; Dibbern, Elizabeth M.; Chaney, Eric J.; Oldenburg, Amy L.; Suslick, Kenneth S.; Boppart, Stephen A.

    2008-02-01

    Optical coherence tomography (OCT) is an emerging biomedical imaging modality that has been developed over the last 15 years. More recently, OCT has been used for the intraoperative imaging of tumor margins in breast cancer and axillary lymph nodes providing a real time in-vivo assessment of the tissue morphology. Traditional OCT images are limited by only being able to observe morphological structures. As diagnostic medicine continues to push for earlier detection, one must develop functional imaging modalities that would detect molecular information in-vivo allowing a real-time microscopic analysis of the tissue specimen. A novel modality of OCT called magnetomotive-OCT (MMOCT) has been developed by our group, employing an induced modulated magnetic field with a magnetic contrast agent to create the added contrast to structural OCT images. Modified protein microspheres with a BSA protein shell functionalized with RGD peptide sequences for targeting and an oil core have been designed and synthesized. Magnetic nanoparticles (Fe3O4) and Nile Red dye have been encapsulated into its oil core. These microspheres have previously been demonstrated to target cancer cells by functionalizing them with a layer of RGD peptides and could be functionalized with monoclonal antibodies. Preliminary results show that these magnetic microspheres, which are 2.0- 5.0 microns in size, are readily detectable under MM-OCT when embedded in a 5% agarose gel, in a 3-D scaffold of macrophage cells previously incubated with the microspheres, and when injected in-vivo into a tumor from an NMUcarcinogen rat animal model for breast cancer.

  2. Magnetic poly(2-hydroxyethyl methacrylate) microspheres for affinity purification of antibodies for early diagnosis of multiple sclerosis patients.

    PubMed

    Horak, Daniel; Hlidkova, Helena; Kit, Yurii; Stoika, Rostyslav; Antonyuk, Volodymyr; Myronovsky, Severyn

    2017-03-28

    The aim of this work is to develop new magnetic polymer microspheres with functional groups available for easy protein and antibody binding. Monodisperse macroporous poly(2-hydroxyethyl methacrylate) (PHEMA-COOH) microspheres ca. 4 µm in diameter and containing ~ 1 mmol COOH/g were synthesized by multistep swelling polymerization of 2-hydroxyethyl methacrylate (HEMA), ethylene dimethacrylate (EDMA), and [(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA), which was followed by MCMEMA hydrolysis. The microspheres were rendered magnetic by precipitation of iron oxide inside the pores, which made them easily separable in a magnetic field. Properties of the resulting magnetic poly(2-hydroxyethyl methacrylate) (mgt.PHEMA) particles with COOH functionality were examined by scanning and transmission electron microscopy (SEM and TEM), static volumetric adsorption of helium and nitrogen, mercury porosimetry, Fourier-transform infrared (FTIR) and atomic absorption spectroscopy (AAS), and elemental analysis. Mgt.PHEMA microspheres were coupled with p46/Myo1C protein purified from blood serum of multiple sclerosis (MS) patients, which enabled easy isolation of monospecific anti-p46/Myo1C immunoglobulin G (IgG) antibodies from crude antibody preparations of mouse blood serum. High efficiency of this approach was confirmed by SDS-PAGE, Western blot, and dot blot analyses. The newly developed mgt.PHEMA microspheres conjugated with a potential disease biomarker, p46/Myo1C protein, are thus a promising tool for affinity purification of antibodies, which can improve diagnosis and treatment of MS patients.

  3. Multifunctional Microspheres Encoded with Upconverting Nanocrystals and Magnetic Nanoparticles for Rapid Separation and Immunoassays.

    PubMed

    Zhang, Ying; Dong, Chunhong; Su, Lin; Wang, Hanjie; Gong, Xiaoqun; Wang, Huiquan; Liu, Junqing; Chang, Jin

    2016-01-13

    Immunoassays based on the downconversion target materials (organic dyes or quantum dots) lead to fairly strong spectral interference between the coded signal and reporter signal, which seriously affects the detection accuracy and hampers their applications. In this work, a new kind of upconverting nanocrystals encoded magnetic microspheres (UCNMMs) were designed and prepared successfully to solve the problem mentioned above. The UCNMMs were obtained by incorporating magnetic Fe3O4 nanoparticles and upconverting nanocrystals with polystyrene microspheres. Due to that upconverting nanocrystals (UCNs) and reporter signals are excitated by near-infrared and UV/visible light separately, immunoassays based on UCNMMs do not occur optical spectral interferences. Furthermore, these new functionalized UCNMMs have excellent properties in binding biomolecules and fast separating, which would have large potential applications in multiplexed assays.

  4. Microspheres

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Vital information on a person's physical condition can be obtained by identifying and counting the population of T-cells and B-cells, lymphocytes of the same shape and size that help the immune system protect the body from the invasion of disease. The late Dr. Alan Rembaum developed a method for identifying the cells. The method involved tagging the T-cells and B-cells with microspheres of different fluorescent color. Microspheres, which have fluorescent dye embedded in them, are chemically treated so that they can link with antibodies. With the help of a complex antibody/antigen reaction, the microspheres bind themselves to specific 'targets,' in this case the T-cells or B-cells. Each group of cells can then be analyzed by a photoelectronic instrument at different wavelengths emitted by the fluorescent dyes. Same concept was applied to the separation of cancer cells from normal cells. Microspheres were also used to conduct many other research projects. Under a patent license Magsphere, Inc. is producing a wide spectrum of microspheres on a large scale and selling them worldwide for various applications.

  5. Preparation of monodisperse magnetic polymer microspheres by swelling and thermolysis technique.

    PubMed

    Yang, Chengli; Shao, Qian; He, Jie; Jiang, Biwang

    2010-04-06

    A novel process for the preparation of monodisperse magnetic polymer microspheres by uniquely combining swelling and thermolysis technique was reported. The monodisperse polystyrene microspheres were first prepared by dispersion polymerization and swelled in chloroform. Then, ferric oleate was dispersed in chloroform as a precursor and impregnated into the swollen polymer microspheres. Subsequently, the iron oxide nanoparticles were formed within the polymer matrix by thermal decomposition of ferric oleate. The morphology, inner structure, and magnetic properties of the magnetic polymer microspheres were studied with a field emission scanning electron microscope (SEM), transmission electron microscope (TEM), and superconducting quantum interference device (SQUID) magnetometer. The results showed that the average diameter of the magnetic polymer microspheres was 5.1 microm with a standard deviation of 0.106, and the magnetic polymer microspheres with saturation magnetization of 12.6 emu/g exhibited distinct superparamagnetic characteristics at room temperature. More interestingly, the magnetite nanoparticles with a spinel structure are evenly distributed over the whole area of the polymer microspheres. These magnetic polymer microspheres have potential applications in biotechnology.

  6. Preparation and adsorption properties of magnetic CoFe2O4-chitosan composite microspheres

    NASA Astrophysics Data System (ADS)

    Lian, Qi; Zheng, Xue-Fang; Hu, Tie-Feng

    2015-11-01

    Magnetic chitosan microspheres made from novel polymer materials show outstanding applied characteristics. Magnetic chitosan microspheres are rather cheap, non-toxic, tasteless, alkali resistant, corrosion resistant, easily degradable, easily recyclable, and so on. It can be widely used in many fields. In this paper, magnetic CoFe2O4/chitosan core-shell microspheres are prepared by means of emulsification cross-linking technique using CoFe2O4 as core and glutaric dialdehyde as crosslinking agent. The results demonstrated that the different calcining temperature of magnetic (CoFe2O4) particles, CoFe2O4/chitosan ratio and stirring time of the suspension medium are the most effective parameters that control the size, size distribution, morphology and magnetism of the described microspheres. Finally, the size, morphology and chemical structure of the prepared materials are studied by different methods. The results show that the optimal calcination temperature of magnetic particles is 700°C, the optimal ratio of CoFe2O4/chitosan is 1: 1, ultrasonic dispersion time is 30 min. The prepared chitosan magnetic microspheres have small size and are well dispersed when the stirring time is 3 h. The prepared magnetic chitosan microspheres are well shaped spheres with a diameter from 1 to 50 μm, in which CoFe2O4 particles are dispersed uniformly. The magnetic chitosan microspheres show excellent magnetic response and have good adsorption characteristics.

  7. MRI visible drug eluting magnetic microspheres for transcatheter intra-arterial delivery to liver tumors.

    PubMed

    Kim, Dong-Hyun; Chen, Jeane; Omary, Reed A; Larson, Andrew C

    2015-01-01

    Magnetic resonance imaging (MRI)-visible amonafide-eluting alginate microspheres were developed for targeted arterial-infusion chemotherapy. These alginate microspheres were synthesized using a highly efficient microfluidic gelation process. The microspheres included magnetic clusters formed by USPIO nanoparticles to permit MRI and a sustained drug-release profile. The biocompatibility, MR imaging properties and amonafide release kinetics of these microspheres were investigated during in vitro studies. A xenograft rodent model was used to demonstrate the feasibility to deliver these microspheres to liver tumors using hepatic transcatheter intra-arterial infusions and potential to visualize the intra-hepatic delivery of these microspheres to both liver tumor and normal tissues with MRI immediately after infusion. This approach offer the potential for catheter-directed drug delivery to liver tumors for reduced systemic toxicity and superior therapeutic outcomes.

  8. MRI Visible Drug Eluting Magnetic Microspheres for Transcatheter Intra-Arterial Delivery to Liver Tumors

    PubMed Central

    Kim, Dong-Hyun; Chen, Jeane; Omary, Reed A.; Larson, Andrew C.

    2015-01-01

    Magnetic resonance imaging (MRI)-visible amonafide-eluting alginate microspheres were developed for targeted arterial-infusion chemotherapy. These alginate microspheres were synthesized using a highly efficient microfluidic gelation process. The microspheres included magnetic clusters formed by USPIO nanoparticles to permit MRI and a sustained drug-release profile. The biocompatibility, MR imaging properties and amonafide release kinetics of these microspheres were investigated during in vitro studies. A xenograft rodent model was used to demonstrate the feasibility to deliver these microspheres to liver tumors using hepatic transcatheter intra-arterial infusions and potential to visualize the intra-hepatic delivery of these microspheres to both liver tumor and normal tissues with MRI immediately after infusion. This approach offer the potential for catheter-directed drug delivery to liver tumors for reduced systemic toxicity and superior therapeutic outcomes. PMID:25767615

  9. Fabrication and Characterization of Monodisperse Magnetic Porous Nickel Microspheres as Novel Catalysts

    NASA Astrophysics Data System (ADS)

    Teng, Chao; He, Jie; Zhu, Lili; Ren, Lianbing; Chen, Jiwei; Hong, Mei; Wang, Yong

    2015-10-01

    A facile and efficient hard-templating strategy is reported for the preparation of porous nickel microspheres with excellent uniformity and strong magnetism. The strategy involves impregnation of porous polymer microspheres with nickel precursors, calcination to remove the template, followed by thermal reduction. The morphology, structure, and the property of the Ni microspheres were characterized by scanning electron microscopy, X-ray powder diffraction, N2 adsorption-desorption isotherms, thermogravimetric analysis, and magnetic hysteresis measurement. The obtained porous nickel microspheres were monodispersed with a particle size of 0.91 μm and crystallite size of 52 nm. Their saturation magnetization was much higher than that of Ni nanoparticles. The unique porous nanostructured Ni microspheres possess catalytic activity and excellent recyclability, as demonstrated in the catalytic reduction of 4-nitrophenol to 4-aminophenol. The micropherical Ni catalysts could be easily separated either by an external magnetic field or by simple filtration.

  10. Chiral magnetic microspheres purified by centrifugal field flow fractionation and microspheres magnetic chiral chromatography for benzoin racemate separation

    PubMed Central

    Tian, Ailin; Qi, Jing; Liu, Yating; Wang, Fengkang; Ito, Yoichiro; Wei, Yun

    2013-01-01

    Separation of enantiomers still remains a challenge due to their identical physical and chemical properties in a chiral environment, and the research on specific chiral selector along with separation techniques continues to be conducted to resolve individual enantiomers. In our laboratory the promising magnetic chiral microspheres Fe3O4@SiO2@cellulose-2, 3-bis (3, 5-dimethylphenylcarbamate) have been developed to facilitate the resolution using both its magnetic property and chiral recognition ability. In our present studies this magnetic chiral selector was first purified by centrifuge field flow fractionation, and then used to separate benzoin racemate by a chromatographic method. Uniform-sized and masking-impurity-removed magnetic chiral selector was first obtained by field flow fractionation with ethanol through a spiral column mounted on the type-J planetary centrifuge, and using the purified magnetic chiral selector, the final chromatographic separation of benzoin racemate was successfully performed by eluting with ethanol through a coiled tube (wound around the cylindrical magnet to retain the magnetic chiral selector as a stationary phase) submerged in dry ice. In addition, an external magnetic field facilitates the recycling of the magnetic chiral selector. PMID:23891368

  11. Preparation and Characterization of Chitosan Poly(acrylic acid) Magnetic Microspheres

    PubMed Central

    Guo, Liang; Liu, Guang; Hong, Ruo-Yu; Li, Hong-Zhong

    2010-01-01

    Spherical microparticles, capable of responding to magnetic fields, were prepared by encapsulating dextran-coated Fe3O4 nanoparticles into chitosan poly(acrylic acid) (PAA) microspheres template. The obtained magnetic microspheres were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and thermogravimetry (TG). The results showed that the microspheres were formed and demonstrated magnetic behavior in an applied magnetic field. In addition, magnetite particles were well encapsulated and the composite particles have high magnetite content, which was more than 40%. PMID:20714433

  12. Indirect voltammetric determination of trace hydroxylamine using magnetic microspheres.

    PubMed

    Yang, Ming; Zhu, Jun-Jie

    2003-02-01

    A new indirect voltammetric method for the determination of hydroxylamine is described. It is based on the reduction of an electroactive derivative of hydroxylamine on the surface of a magnetic electrode. The electroactive derivative produced by hydroxylamine reacted with magnetic polymer microspheres containing carbonyl groups on the surface. The experimental conditions are discussed. It was found that the peak potential (Ep) of the derivative was -0.46 V (vs. Ag/AgCl) under optimum conditions. Hydroxylamine could be determined in the range of 5-2,000 microg l(-1) with the detection limit of 2 microg l(-1) and relative standard deviation for the determination of 100 microg l(-1) hydroxylamine was 2.35%. Satisfactory results were obtained for the determination of hydroxylamine in aqueous medium.

  13. Toward designer magnetite/polystyrene colloidal composite microspheres with controllable nanostructures and desirable surface functionalities.

    PubMed

    Xu, Shuai; Ma, Wan-Fu; You, Li-Jun; Li, Ju-Mei; Guo, Jia; Hu, Jack J; Wang, Chang-Chun

    2012-02-14

    An effective method was developed for synthesizing magnetite/polymer colloidal composite microspheres with controllable variations in size and shape of the nanostructures and desirable interfacial chemical functionalities, using surfactant-free seeded emulsion polymerization with magnetite (Fe(3)O(4)) colloidal nanocrystal clusters (CNCs) as the seed, styrene (St) as the monomer, and potassium persulfate (KPS) as the initiator. The sub-micrometer-sized citrate-acid-stabilized Fe(3)O(4) CNCs were first obtained via ethylene glycol (EG)-mediated solvothermal synthesis, followed by 3-(trimethoxysilyl)propyl methacrylate (MPS) modification to immobilize the active vinyl groups onto the surfaces, and then the hydrophobic St monomers were polymerized at the interfaces to form the polymer shells by seeded emulsion radical polymerization. The morphology of the composite microspheres could be controlled from raspberry- and flower-like shapes, to eccentric structures by simply adjusting the feeding weight ratio of the seed to the monomer (Fe(3)O(4)/St) and varying the amount of cross-linker divinyl benzene (DVB). The morphological transition was rationalized by considering the viscosity of monomer-swollen polymer matrix and interfacial tension between the seeds and polymer matrix. Functional groups, such as carboxyl, hydroxyl, and epoxy, can be facilely introduced onto the composite microspheres through copolymerization of St with other functional monomers. The resultant microspheres displayed a high saturation magnetization (46 emu/g), well-defined core-shell nanostructures, and surface chemical functionalities, as well as a sustained colloidal stability, promising for further biomedical applications.

  14. Fabrication of monodisperse, large-sized, functional biopolymeric microspheres using a low-cost and facile microfluidic device.

    PubMed

    Zhu, Liping; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi; Zhu, Meifang

    2010-02-01

    We report a novel and facile method for fabricating coaxial microfluidic devices processing various dimensions at low cost, in which polypropylene hollow fibers or glass capillaries are used as the tip of the dispersed phase injection tube. With this coaxial microfluidic device,monodisperse biocompatible microspheres ranging from 300 to 800 μm were obtained by collecting oil-in-water or water-in-oil emulsions and solidifying the suspended microspheres. Microsphere size could be controlled by changing the tips or tuning the concentrations of the dispersed and continuous phases. By adding functional nanoparticles into the dispersed phase, it was demonstrated that fluorescent and magnetic microspheres can be fabricated easily using these microfluidic devices.

  15. Biotemplate-directed fabrication of size-controlled monodisperse magnetic silica microspheres.

    PubMed

    Zhang, Bo; Yang, Shan; Zhang, Yuan; Wang, Quanxi; Ren, Tianrui

    2015-07-01

    Biotemplating is an effective strategy to obtain morphology-controllable materials with structural specificity, complexity, and corresponding unique functions. Herein we take advantage of the unique heavy-metal-ion biosorption behavior of cyanobacteria cells to fabricate Fe3O4/cell composites. Meanwhile, cyanobacteria cells served as a biotemplate for fabricating solid and hollow magnetic silica microspheres (MSMs). The obtained MSMs retained the original morphology of the cells, and exhibited excellent monodispersity and uniform spherical shape with narrow size distribution. Furthermore, they demonstrated ferromagnetic behavior at room temperature when measured using a vibrating sample magnetometer. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Novel electrochemical immunoassay for human IgG1 using metal sulfide quantum dot-doped bovine serum albumin microspheres on antibody-functionalized magnetic beads.

    PubMed

    Chen, Zongbao; Lu, Minghua

    2017-08-01

    A new magneto-controlled electrochemical immunosensing system was developed for the sensitive detection of low-abundance protein (IgG1 used in this case) with a sandwich-type assay format on monoclonal mouse anti-human Fab-specific IgG1-functionalized magnetic bead. Metal sulfide (CdS) quantum dot-doped bovine serum albumin (QD-BSA) was synthesized and functionalized with monoclonal Fc-specific anti-human antibody. In the presence of IgG1, the immobilized antibody on magnetic bead was selective to capture the Fab region of the analyte, followed to be sandwiched by the conjugated antibody onto QD-BSA. The subsequent anodic stripping voltammetric analysis of cadmium ion, released by acid from quantum dot, was conducted at an in situ prepared mercury film electrode. Under optimal conditions, the voltammetric current increased with the increasing of target IgG1 within a dynamic working range from 10 pg mL(-1) to 100 ng mL(-1). The limit of detection of this immunosensor was evaluated to 3.4 pg mL(-1) at 3sblank criterion. The precision, selectivity and method accuracy were acceptable. Analysis of human serum samples revealed good accordance with the results obtained by commercial enzyme-linked immunosorbent assay method. Importantly, this concept offers promise for cost-effective analysis of low-abundance cancer biomarkers without the need of natural enzymes. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Highly Sensitive and Reproducible SERS Performance from Uniform Film Assembled by Magnetic Noble Metal Composite Microspheres.

    PubMed

    Niu, Chunyu; Zou, Bingfang; Wang, Yongqiang; Cheng, Lin; Zheng, Haihong; Zhou, Shaomin

    2016-01-26

    To realize highly sensitive and reproducible SERS performance, a new route was put forward to construct uniform SERS film by using magnetic composite microspheres. In the experiment, monodisperse Fe3O4@SiO2@Ag microspheres with hierarchical surface were developed and used as building block of SERS substrate, which not only realized fast capturing analyte through dispersion and collection under external magnet but also could be built into uniform film through magnetically induced self-assembly. By using R6G as probe molecule, the as-obtained uniform film exhibited great improvement on SERS performance in both sensitivity and reproducibility when compared with nonuniform film, demonstrating the perfect integration of high sensitivity of hierarchal noble metal microspheres and high reproducibility of ordered microspheres array. Furthermore, the as-obtained product was used to detect pesticide thiram and also exhibited excellent SERS performance for trace detection.

  18. Maltodextrin-modified magnetic microspheres for selective enrichment of maltose binding proteins.

    PubMed

    Zheng, Jin; Ma, Chongjun; Sun, Yangfei; Pan, Miaorong; Li, Li; Hu, Xiaojian; Yang, Wuli

    2014-03-12

    In this work, maltodextrin-modified magnetic microspheres Fe3O4@SiO2-Maltodextrin (Fe3O4@SiO2-MD) with uniform size and fine morphology were synthesized through a facile and low-cost method. As the maltodextrins on the surface of microspheres were combined with maltose binding proteins (MBP), the magnetic microspheres could be applied to enriching standard MBP fused proteins. Then, the application of Fe3O4@SiO2-MD in one-step purification and immobilization of MBP fused proteins was demonstrated. For the model protein we examined, Fe3O4@SiO2-MD showed excellent binding selectivity and capacity against other Escherichia coli proteins in the crude cell lysate. Additionally, the maltodextrin-modified magnetic microspheres can be recycled for several times without significant loss of binding capacity.

  19. Reorientation Response of Magnetic Microspheres Attached to Gold Electrodes Under an Applied Magnetic Field

    NASA Astrophysics Data System (ADS)

    De Los Santos Valladares, L.; Dominguez, A. Bustamante; Aguiar, J. Albino; Reeve, R. M.; Mitrelias, T.; Langford, R. M.; Azuma, Y.; Barnes, C. H. W.; Majima, Y.

    2013-08-01

    In this work, we report the mechanical reorientation of thiolated ferromagnetic microspheres bridging a pair of gold electrodes under an external magnetic field. When an external magnetic field (7 kG) is applied during the measurement of the current-voltage characteristics of a carboxyl ferromagnetic microsphere (4 μm diameter) attached to two gold electrodes by self-assembled monolayers (SAMs) of octane dithiol (C8H18S2), the current signal is distorted. Rather than due to magnetoresistance, this effect is caused by a mechanical reorientation of the ferromagnetic sphere, which alters the number of SAMs between the sphere and the electrodes and therefore affects conduction. To study the physical reorientation of the ferromagnetic particles, we measure their hysteresis loops while suspended in a liquid solution.

  20. Detection of Mycobacterium tuberculosis based on H37R(v) binding peptides using surface functionalized magnetic microspheres coupled with quantum dots – a nano detection method for Mycobacterium tuberculosis.

    PubMed

    Yang, Hua; Qin, Lianhua; Wang, Yilong; Zhang, Bingbo; Liu, Zhonghua; Ma, Hui; Lu, Junmei; Huang, Xiaochen; Shi, Donglu; Hu, Zhongyi

    2015-01-01

    Despite suffering from the major disadvantage of low sensitivity, microscopy of direct smear with the Ziehl-Neelsen stain is still broadly used for detection of acid-fast bacilli and diagnosis of tuberculosis. Here, we present a unique detection method of Mycobacterium tuberculosis (MTB) using surface functionalized magnetic microspheres (MMSs) coupled with quantum dots (QDs), conjugated with various antibodies and phage display-derived peptides. The principle is based upon the conformation of the sandwich complex composed of bacterial cells, MMSs, and QDs. The complex system is tagged with QDs for providing the fluorescent signal as part of the detection while magnetic separation is achieved by MMSs. The peptide ligand H8 derived from the phage display library Ph.D.-7 is developed for MTB cells. Using the combinations of MMS-polyclonal antibody+QD-H8 and MMS-H8+QD-H8, a strong signal of 10(3) colony forming units (CFU)/mL H37R(v) was obtained with improved specificity. MS-H8+QD-H8 combination was further optimized by adjusting the concentrations of MMSs, QDs, and incubation time for the maximum detection signal. The limit of detection for MTB was found to reach 10(3) CFU/mL even for the sputum matrices. Positive sputum samples could be distinguished from control. Thus, this novel method is shown to improve the detection limit and specificity of MTB from the sputum samples, and to reduce the testing time for accurate diagnosis of tuberculosis, which needs further confirmation of more clinical samples.

  1. Magnetically stimulated ciprofloxacin release from polymeric microspheres entrapping iron oxide nanoparticles

    PubMed Central

    Sirivisoot, Sirinrath; Harrison, Benjamin S

    2015-01-01

    To extend the external control capability of drug release, iron oxide nanoparticles (NPs) encapsulated into polymeric microspheres were used as magnetic media to stimulate drug release using an alternating magnetic field. Chemically synthesized iron oxide NPs, maghemite or hematite, and the antibiotic ciprofloxacin were encapsulated together within polycaprolactone microspheres. The polycaprolactone microspheres entrapping ciprofloxacin and magnetic NPs could be triggered for immediate drug release by magnetic stimulation at a maximum value of 40%. Moreover, the microspheres were cytocompatible with fibroblasts in vitro with a cell viability percentage of more than 100% relative to a nontreated control after 24 hours of culture. Macrophage cell cultures showed no signs of increased inflammatory responses after in vitro incubation for 56 hours. Treatment of Staphylococcus aureus with the magnetic microspheres under an alternating (isolating) magnetic field increased bacterial inhibition further after 2 days and 5 days in a broth inhibition assay. The findings of the present study indicate that iron oxide NPs, maghemite and hematite, can be used as media for stimulation by an external magnetic energy to activate immediate drug release. PMID:26185446

  2. The preparation and properties of monodisperse core-shell silica magnetic microspheres.

    PubMed

    Lou, Min-yi; Jia, Qiu-ling; Wang, De-ping; Liu, Bing; Huang, Wen-hai

    2008-01-01

    The monodisperse core-shell silica magnetic microspheres (MMS) were synthesized by sol-gel method gelling in the emulsion. Optical microscope (OM), field emission scanning electron microscope (FESEM), nitrogen adsorption and desorption Brunauer Emmett Teller Procedure (BET) isotherms and Barrett-Joyner-Halenda (BJH) pore size distribution measurements, X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and vibrating sample magnetometer (VSM) were used to characterize the appearance, size distribution, phase, specific surface area, chemical composition and magnetic property of silica MMS. The results showed that silica MMS prepared through sol-gel method with acid-alkali two-step catalyze and gelling in emulsion exhibited the superior core-shell structure and size distribution of the microspheres concentrated in about 20 mum. The main phase of microspheres was amorphous silica and spinel ferroferric oxide. Meanwhile, the microspheres remained the superparamagnetic behavior and could be used as biomaterials.

  3. Photofunctional hybrid silica microspheres covalently functionalized with metalloporphyrins

    NASA Astrophysics Data System (ADS)

    Guo, Lei; Fu, Lianshe; Ferreira, Rute A. S.; Carlos, Luis D.; Yan, Bing

    2012-10-01

    The entrapment of metalloporphyrins (with Zn2+ and Yb3+) in silica microspheres is achieved by modification of protoporphyrin IX (Pp-IX) molecules with three different organosilane precursors via the sol-gel method. The obtained hybrid materials are characterized by electronic absorption spectra, Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), 29Si MAS NMR spectrum, scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherms and thermogravimetric analysis (TGA), and their luminescence properties have also been determined. The results reveal that the obtained porphyrins networks are covalently bonded to the inorganic matrix through the bridging action of the functionalized silica microspheres. Furthermore, it has also been observed that porphyrins molecules located in different environments exhibit different photophysical properties in the visible and near-infrared regions.

  4. Biomass Vanillin-Derived Polymeric Microspheres Containing Functional Aldehyde Groups: Preparation, Characterization, and Application as Adsorbent.

    PubMed

    Zhang, Huanyu; Yong, Xueyong; Zhou, Jinyong; Deng, Jianping; Wu, Youping

    2016-02-03

    The contribution reports the first polymeric microspheres derived from a biomass, vanillin. It reacted with methacryloyl chloride, providing monomer vanillin methacrylate (VMA), which underwent suspension polymerization in aqueous media and yielded microspheres in high yield (>90 wt %). By controlling the N2 bubbling mode and by optimizing the cosolvent for dissolving the solid monomer, the microspheres were endowed with surface pores, demonstrated by SEM images and mercury intrusion porosimetry measurement. Taking advantage of the reactive aldehyde groups, the microspheres further reacted with glycine, thereby leading to a novel type of Schiff-base chelating material. The functionalized microspheres demonstrated remarkable adsorption toward Cu(2+) (maximum, 135 mg/g) which was taken as representative for metal ions. The present study provides an unprecedented class of biobased polymeric microspheres showing large potentials as adsorbents in wastewater treatment. Also importantly, the reactive aldehyde groups may enable the microspheres to be used as novel materials for immobilizing biomacromolecules, e.g. enzymes.

  5. Investigation on efficient adsorption of cationic dyes on porous magnetic polyacrylamide microspheres.

    PubMed

    Yao, Tong; Guo, Song; Zeng, Changfeng; Wang, Chongqing; Zhang, Lixiong

    2015-07-15

    We report here the preparation of porous magnetic polyacrylamide microspheres for efficient removal of cationic dyes by a simple polymerization-induced phase separation method. Characterizations by various techniques indicate that the microspheres show porous structures and magnetic properties. They can adsorb methylene blue with high efficiency, with adsorption capacity increasing from 263 to 1977 mg/g as the initial concentration increases from 5 to 300 mg/L. Complete removal of methylene blue can be obtained even at very low concentrations. The equilibrium data is well described by the Langmuir isotherm models, exhibiting a maximum adsorption capacity of 1990 mg/g. The adsorption capacity increases with increasing initial pH and reaches a maximum at pH 8, revealing an electrostatic interaction between the microspheres and the methylene blue molecules. The microspheres also show high adsorption capacities for neutral red and gentian violet of 1937 and 1850 mg/g, respectively, as well as high efficiency in adsorption of mixed-dye solutions. The dye-adsorbed magnetic polyacrylamide microspheres can be easily desorbed, and can be repeatedly used for at least 6 cycles without losing the adsorption capacity. The adsorption capacity and efficiency of the microspheres are much higher than those of reported adsorbents, which exhibits potential practical application in removing cationic dyes.

  6. Magnetic nanoparticles-loaded PLA/PEG microspheres as drug carriers.

    PubMed

    Frounchi, Masoud; Shamshiri, Soodeh

    2015-05-01

    Surface-modified magnetite (Fe3 O4 ) nanoparticles with an average size of 22 nm were prepared. The nanoparticles had a saturation magnetization of 50.7 emu g(-1) . Then magnetite and drug-loaded microspheres of poly (lactic acid)/poly (ethylene glycol) were prepared at various compositions. The microspheres were spherical in shape and had smooth surface. The diameter size of the microspheres ranged between about 0.2 and 4 μm. Doxorubicin hydrochloride for cancer treatment was the drug that loaded into the microspheres. The prepared microspheres were characterized by FTIR, XRD, VSM, SEM and drug-release measurements. It was found that the drug cumulative release percentage was proportional to (time) (n) where 0.61 < n < 0.75 depending on PEG and Fe3 O4 contents. The drug release was controlled through a combination of diffusion and PLA hydrolysis and obeyed a non-fickian mechanism. The drug release was facilitated by presence of poly (ethylene glycol) as PLA plasticizer and was higher under applied external magnetic field. The obtained magnetic microspheres could be used as drug carriers for targeted drug delivery purposes.

  7. [Experimental study of magnetic pingyangmycine-bearing microspheres in the treatment of cavernous hemangioma].

    PubMed

    Zhang, Sheng; Wu, Han-jiang; Ling, Tian-you

    2003-02-28

    To investigate the probability and mechanism magnetic pingyangmycine-bearing microspheres(MPMs) in the treatment of cavernous hemangioma. Twenty rabbits were divided into four groups. MPMs, pingyangmycine and magnetic nonpingyangmycine-bearing microspheres were injected into marginal ear veins respectively. All animals were killed after 21 days and histological varations of the veins were observed under the light microscope and transmission electron microscope. The occlusion of the veins in the group of MPMs with the external magnetic field was more prominent than that in the other groups. MPMs can occlude veins by means of its embolized effect and PYM drug effect. MPMs may be better used in the therapy of cavernous hemangioma.

  8. Multifunctional microsphere formulation of fluorescent magnetic properties for drug delivery system

    NASA Astrophysics Data System (ADS)

    Kusrini, Eny; Prassanti, Riesna; Nurjaya, Dwi Marta; Gunawan, Cindy

    2017-02-01

    The microsphere formulations of Chit/TPP/Sm/Fe3O4/Rn were prepared by an ionic gelation technique, where Chit=chitosan, TPP=tripolyphosphate, Sm=samarium and Rn=ranitidine. Optimum of microsphere formulation exhibit magnetic and fluorescent properties with adsorption efficiency of ˜92% was obtained for Chit/TPP/Sm/Fe3O4/Rn with ratio 400:500:50:1:20. Fluorescence intensity of microsphere formulations increased with the cumulative amount release of ranitidine, so that the changing of fluorescence intensity at wavelength of 590 nm referring to the Sm3+ ion could be used as indicator in DDS. With the demonstration of sustained release from microsphere formulation, it allows to investigate the applications to other drugs.

  9. Reversible immobilization of laccase onto metal-ion-chelated magnetic microspheres for bisphenol A removal.

    PubMed

    Lin, Jiahong; Liu, Yingju; Chen, Shi; Le, Xueyi; Zhou, Xiaohua; Zhao, Zhiyong; Ou, Yiyi; Yang, Jianhua

    2016-03-01

    Increasing attention has been given to nanobiocatalysis for commercial applications. In this study, laccase was reversibly immobilized onto Cu(ΙΙ)- and Mn(ΙΙ)-chelated magnetic microspheres and successfully applied to remove bisphenol A (BPA) from water. The results indicated that the loading of laccase onto the metal-ion-chelated magnetic microspheres was approximately 100mg/g. After five successive adsorption-desorption cycles, the laccase adsorption capacities did not change. In comparison with free laccase, the thermal and storage stabilities of immobilized laccase were significantly improved. Immobilized laccase exhibited a high removal efficiency for BPA under the combined actions of biodegradation and adsorption. Greater than 85% of BPA was removed under optimum conditions. The effects of various factors on the BPA removal efficiency of immobilized laccase were analysed. The results showed that metal-ion-chelated magnetic microspheres have great potential for industrial applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Magnetic field activated drug release system based on magnetic PLGA microspheres for chemo-thermal therapy.

    PubMed

    Fang, Kun; Song, Lina; Gu, Zhuxiao; Yang, Fang; Zhang, Yu; Gu, Ning

    2015-12-01

    Controlled drug delivery systems have been extensively investigated for cancer therapy in order to obtain better specific targeting and therapeutic efficiency. Herein, we developed doxorubicin-loaded magnetic PLGA microspheres (DOX-MMS), in which DOX was encapsulated in the core and high contents (28.3 wt%) of γ-Fe2O3 nanoparticles (IOs) were electrostatically assembled on the surface of microsphere to ensure the high sensitivity to response of an external alternating current magnetic field (ACMF). The IOs in PLGA shell can both induce the heat effect and trigger shell permeability enhancement to release drugs when DOX-MMs was activated by ACMF. Results show that the cumulative drug release from DOX-MMs exposed to ACMF for 30 min (21.6%) was significantly higher (approximately 7 times higher) than that not exposed to ACMF (2.8%). The combination of hyperthermia and enhanced DOX release from DOX-MMS is beneficial for in vitro 4T1 breast cancer cell apoptosis as well as effective inhibition of tumor growth in 4T1 tumor xenografts. Therefore, the DOX-MMS can be optimized as powerful delivery system for efficient magnetic responsive drug release and chemo-thermal therapy.

  11. Novel smart chiral magnetic microspheres for enantioselective adsorption of tryptophan enantiomers

    NASA Astrophysics Data System (ADS)

    Guo, Lian-Di; Song, Ya-Ya; Yu, Hai-Rong; Pan, Li-Ting; Cheng, Chang-Jing

    2017-06-01

    Multifunctional microspheres simultaneously possessing chirality, magnetism and thermosensitivity show great potentials in direct enantiomeric separation. Herein we report a novel type of smart chiral magnetic microspheres with core/shell/shell structures (Fe3O4@SiO2@PNCD) and its application in enantioselective adsorption of tryptophan (Trp) enantiomers. The prepared Fe3O4@SiO2@PNCD are composed of a Fe3O4 nanoparticle core, an acidic-resistant SiO2 middle shell and a thermosensitive microgel functional shell (PNCD). The PNCD plays an important role in the enantioselective adsorption of Trp enantiomers. The β-cyclodextrin (β-CD) molecules on the PNCD act as smart receptors or chiral selectors, and can selectively recognize and bind L-Trp enantiomers into their cavities by forming host-guest inclusion complexes. The poly(N-isopropylacrylamide) (PNIPAM) chains on the PNCD serve as microenvironmental adjustors for the association constants of β-CD/L-Trp complexes. The fabricated Fe3O4@SiO2@PNCD demonstrate fascinating temperature-responsive chiral recognition and adsorption selectivity toward Trp enantiomers. Most importantly, the desorption of Trp enantiomers and the regeneration of the Fe3O4@SiO2@PNCD can be easily achieved via simply changing the operation temperature. Moreover, the regenerated Fe3O4@SiO2@PNCD can be readily recovered from the amino acids enantiomeric solution under an external magnetic field for reuse. The present study provides a novel strategy for the direct enantioselective adsorption and separation of various enantiomeric compounds.

  12. TiO2 microspheres containing magnetic nanoparticles for intra-arterial hyperthermia.

    PubMed

    Kanetaka, Hiroyasu; Liu, Gengci; Li, Zhixia; Miyazaki, Toshiki; Furuya, Maiko; Kudo, Tada-Aki; Kawashita, Masakazu

    2016-08-06

    Magnetic microspheres measuring 15-35 µm in diameter are believed to be useful for intra-arterial hyperthermia. In this study, we attempted to prepare titanium dioxide (TiO2 ) microspheres containing magnetic nanoparticles (MNPs). MNP-containing TiO2 microspheres with diameters of approximately 30 µm were successfully obtained by sol-gel reaction of titanium tetraisopropoxide in a water-in-oil emulsion with added cosurfactant of 1-butanol and subsequent heat treatment at 200°C. The microspheres showed ferrimagnetism owing to high content of MNPs in approximately 60 wt % and had a low-crystalline TiO2 matrix. Furthermore, the agar phantom was heated to above 43°C after approximately 1 min under an alternating magnetic field of 100 kHz and 300 Oe and showed in vitro biocompatibility similar to that of MNP-free TiO2 microspheres. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  13. Magnetic alginate microspheres detected by MRI fabricated using microfluidic technique and release behavior of encapsulated dual drugs

    PubMed Central

    Wang, Qin; Liu, Shanshan; Yang, Fan; Gan, Lu; Yang, Xiangliang; Yang, Yajiang

    2017-01-01

    Alginate microspheres loaded with superparamagnetic iron oxide nanoparticles (SPIO NPs) have been fabricated by a T-junction microfluidic device combined with an external ionic crosslinking. The obtained microspheres possess excellent visuality under magnetic resonance due to the presence of only 0.6 mg/mL SPIO NPs. The microspheres also show uniform size with narrow distribution and regular spherical shape characterized by optic microscope and environmental scanning electron microscope. Furthermore, dual drugs (5-fluorouracil and doxorubicin hydrochloride) have been loaded within the microspheres. The release behavior of dual drugs from the microspheres show typical sustained release profiles. As a novel embolic agent, such microspheres in blood vessels can be tracked by magnetic resonance scanner. Thus, the integration of embolotherapy, chemotherapy, and postoperative diagnosis can be realized. PMID:28652736

  14. Hydrothermal synthesis and magnetic properties of CuO hollow microspheres

    SciTech Connect

    Zhao, J.G.; Yin, J.Z.; Yang, M.

    2014-01-01

    Graphical abstract: - Highlights: • CuO hollow microspheres were synthesized through hydrothermal route. • The possible growth mechanism was proposed according to the experimental results. • CuO hollow microspheres show an anomalous ferromagnetic behavior at 5 K and 300 K. - Abstract: In the present work, CuO hollow microspheres with the diameter about 2 μm were successfully synthesized through a facile hydrothermal method. The phase purity, morphologies and structure features of the as obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy, respectively. It was found that reaction temperature, reaction time and different volume ratios of ethanol and distilled water played important roles on the morphologies of the obtained CuO hollow microspheres. The possible formation mechanism was also proposed according to the corresponding experimental results. The magnetic properties were investigated by superconducting quantum interference device, revealing that the CuO hollow microspheres exhibited an anomalous ferromagnetic behavior at 5 K and 300 K. At the same time, the origin of the ferromagnetism in CuO hollow microspheres was also discussed.

  15. Facile synthesis of magnetic mesoporous hollow carbon microspheres for rapid capture of low-concentration peptides.

    PubMed

    Cheng, Gong; Zhou, Ming-Da; Zheng, Si-Yang

    2014-08-13

    Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g(-1) at room temperature and a Brunauer-Emmett-Teller specific surface area of 48.8 m(2) g(-1) with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications.

  16. Facile Synthesis of Magnetic Mesoporous Hollow Carbon Microspheres for Rapid Capture of Low-Concentration Peptides

    PubMed Central

    2015-01-01

    Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g–1 at room temperature and a Brunauer–Emmett–Teller specific surface area of 48.8 m2 g–1 with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications. PMID:24992375

  17. Restricted access magnetic core-mesoporous shell microspheres with C8-modified interior pore-walls for the determination of diazepam in rat plasma by LC-MS.

    PubMed

    Liu, Xiaodan; Yu, Yingjia; Li, Yan; Ning, Suli; Liu, Tingting; Li, Fajie; Duan, Gengli

    2013-03-15

    In this study, a novel enrichment technique based on magnetic core-mesoporous shell microspheres with C8-modified interior pore-walls (C8-Fe₃O₄@mSiO₂) was successfully developed for the determination of diazepam in rat plasma by LC-MS. Due to the unique properties of the synthesized C8-Fe₃O₄@mSiO₂ microspheres (C8-modified magnetic mesoporous microsphere), small drug molecules like diazepam can enter the mesopore channels and be efficiently absorbed through hydrophobic interaction by interior C8-groups (Octyl functional groups). Large molecules like proteins are excluded from the mesopore channels as a result of size exclusion effect, leading to direct extraction of drug molecules from protein-rich biosmaples such as plasma without any other pretreatment procedure. Moreover, diazepam adsorbed C8-Fe₃O₄@mSiO₂ microspheres could be simply and rapidly isolated through placing a magnet on the bottom of container, and then diazepam could be easily eluted from C8-Fe₃O₄@mSiO₂ microspheres for further LC-MS analysis. Extraction conditions such as amounts of C8-Fe₃O₄@mSiO₂ microspheres added, adsorption time, elution solvent and elution time were investigated. Method validations including linear range, the limit of detection, precision, and recovery were also studied. The results indicated that the proposed method based on C8-Fe₃O₄@mSiO₂ microspheres was simple and accurate for the analysis of diazepam in the rat plasma. And it will provide new ideas for analyzing plasma concentration and pharmacokinetics of similar drugs.

  18. An Electrochemical Genosensing Assay Based on Magnetic Beads and Gold Nanoparticle-Loaded Latex Microspheres for Vibrio cholerae Detection.

    PubMed

    Low, Kim-Fatt; Rijiravanich, Patsamon; Singh, Kirnpal Kaur Banga; Surareungchai, Werasak; Yean, Chan Yean

    2015-04-01

    An ultrasensitive electrochemical genosensing assay was developed for the sequence-specific detection of Vibrio cholerae DNA using magnetic beads as the biorecognition surface and gold nanoparticle-loaded latex microspheres (latex-AuNPs) as a signal-amplified hybridization tag. This biorecognition surface was prepared by immobilizing specific biotinylated capturing probes onto the streptavidin-coupled magnetic beads. Fabricating a hybridization tag capable of amplifying the electrochemical signal involved loading multiple AuNPs onto polyelectrolyte multilayer film-coated poly(styrene-co-acrylic acid) latex microspheres as carrier particles. The detection targets, single-stranded 224-bp asymmetric PCR amplicons of the V. cholerae lolB gene, were sandwich-hybridized to magnetic bead-functionalized capturing probes and fluorescein-labeled detection probes and tagged with latex-AuNPs. The subsequent electrochemical stripping analysis of chemically dissolved AuNPs loaded onto the latex microspheres allowed for the quantification of the target amplicons. The high-loading capacity of the AuNPs on the latex microspheres for sandwich-type dual-hybridization genosensing provided eminent signal amplification. The genosensing variables were optimized, and the assay specificity was demonstrated. The clinical applicability of the assay was evaluated using spiked stool specimens. The current signal responded linearly to the different V. cholerae concentrations spiked into stool specimens with a detection limit of 2 colony-forming units (CFU)/ml. The proposed latex-AuNP-based magnetogenosensing platform is promising, exhibits an effective amplification performance, and offers new opportunities for the ultrasensitive detection of other microbial pathogens.

  19. Preparation of magnetic core-mesoporous shell microspheres with C8-modified interior pore-walls and their application in selective enrichment and analysis of mouse brain peptidome.

    PubMed

    Liu, Shasha; Li, Yan; Deng, Chunhui; Mao, Yu; Zhang, Xiangmin; Yang, Pengyuan

    2011-12-01

    In this paper, magnetic mesoporous silica microspheres with C8-modified interior pore-walls were prepared through a facile one-pot sol-gel coating strategy, and were successfully applied for selective enrichment of endogenous peptides in mouse brain for peptidome analysis. Through the one-pot sol-gel approach with surfactant (CTAB) as a template, tetraethyl orthosilicate (TEOS) and n-ctyltriethoxysilane (C8TEOS) as the precursors, C8-modified magnetic mesoporous microspheres (C8-Fe(3)O(4)@mSiO(2)) consisting magnetic core and mesoporous silica shell with C8-groups exposed in the mesopore channels were synthesized. The obtained microspheres possess highly open mesopores of 3.4 nm, high surface area (162.5 m(2)/g), large pore volume (0.17 cm(3)/g), excellent magnetic responsivity (56.3 emu/g) and good dispersibility in aqueous solution. Based on the abundant surface silanol groups, functional C8 groups and the strong magnetic responsivity of the core-shell C8-Fe(3) O(4) @mSiO(2) microspheres, efficient and fast enrichment of peptides was achieved. Additionally, the C8-Fe(3)O(4)@mSiO(2) microspheres exhibit excellent performance in selective enrichment of endogenous peptides from complex samples that are consist of peptides, large proteins and other compounds, including human serum and mouse brain followed by automated nano-LC-ESI-MS/MS analysis. These results indicate C8-Fe(3)O(4)@mSiO(2) microspheres would be a potential candidate for endogenous peptides enrichment and biomarkers discovery in peptidome analysis.

  20. Preparation of magnetic core mesoporous shell microspheres with C18-modified interior pore-walls for fast extraction and analysis of phthalates in water samples.

    PubMed

    Li, Zhongbo; Huang, Danni; Fu, Chinfai; Wei, Biwen; Yu, Wenjia; Deng, Chunhui; Zhang, Xiangmin

    2011-09-16

    In this study, core-shell magnetic mesoporous microspheres with C18-functionalized interior pore-walls were synthesized through coating Fe(3)O(4) microspheres with a mesoporous inorganic-organic hybrid layer with a n-octadecyltriethoxysilane (C18TES) and tetraethyl orthosilicate (TEOS) as the silica source and cetyltrimethylammonia bromide (CTAB) as a template. The obtained C18-functionalized Fe(3)O(4)@mSiO(2) microspheres possess numerous C18 groups anchored in the interior pore-walls, large surface area (274.7 m(2)/g, high magnetization (40.8 emu/g) and superparamagnetism, uniform mesopores (4.1 nm), which makes them ideal absorbents for simple, fast, and efficient extraction and enrichment of hydrophobic organic compounds in water samples. Several kinds of phthalates were used as the model hydrophobic organic compounds to systematically evaluate the performance of the C18-functionalized Fe(3)O(4)@mSiO(2) microspheres in extracting hydrophobic molecules by using a gas chromatography-mass spectrometry. Various parameters, including eluting solvent, the amounts of absorbents, extraction time and elution time were optimized. Hydrophobic extraction was performed in the interior pore of magnetic mesoporous microspheres, and the materials had the anti-interference ability to macromolecular proteins, which was also investigated in the work. Under the optimized conditions, C18-functionalized Fe(3)O(4)@mSiO(2) microspheres were successfully used to analyze the real water samples. The results indicated that this novel method was fast, convenient and efficient for the target compounds and could avoid being interfered by macromolecules.

  1. Ti(IV) carrying polydopamine-coated, monodisperse-porous SiO2 microspheres with stable magnetic properties for highly selective enrichment of phosphopeptides.

    PubMed

    Salimi, Kouroush; Usta, Duygu Deniz; Çelikbıçak, Ömür; Pinar, Asli; Salih, Bekir; Tuncel, Ali

    2017-02-22

    A marked decrease in the saturation magnetization by the formation of functional shells around the magnetic core is an important disadvantage of magnetic core-shell nanoparticles. Another drawback of Ti(IV)-functionalized immobilized metal affinity chromatography (IMAC) sorbents is the acidic character of the binding medium used for Ti(4+) attachment onto composite magnetic nanoparticles, which causes an additional decrease in the saturation magnetization owing to the chemical interaction between the acidic moiety and the magnetic core. An IMAC sorbent in the form of magnetic microspheres with superior and stable magnetic properties with respect to magnetic core-shell nanoparticles was designed for phosphopeptide enrichment. Magnetic, monodisperse-porous silica microspheres (MagSiO2) 6μm in size were synthesized by a new staged-shape template hydrolysis-condensation protocol. A porous-silica shell layer was generated around the microspheres to protect the magnetic core from the acidic medium during Ti(4+) attachment (MagSiO2@SiO2). The MagSiO2@SiO2 microspheres were coated with a polydopamine shell (MagSiO2@SiO2@PDA) and Ti(4+) was attached onto the composite microspheres (MagSiO2@SiO2@PDA@Ti(IV)). Formation of the PDA layer and Ti(4+) attachment did not cause any significant decrease in the saturation magnetization. The platform exhibited excellent performance for phosphopeptide enrichment from the digests of phosphorylated proteins. Selectivity was investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The detection limit for phosphopeptide enrichment by the MagSiO2@SiO2@PDA@Ti(IV) microspheres from the tryptic digests of β-casein was 50 fmol/mL. Usability of the proposed magnetic sorbent with complex biological samples was demonstrated by successful enrichment of four phosphopeptides from human serum. The proposed sorbent showed stable performance over five repeated uses.

  2. Fractionation of Magnetic Microspheres in a Microfluidic Spiral: Interplay between Magnetic and Hydrodynamic Forces

    PubMed Central

    Hayden, M. E.; Häfeli, U. O.

    2017-01-01

    Magnetic forces and curvature-induced hydrodynamic drag have both been studied and employed in continuous microfluidic particle separation and enrichment schemes. Here we combine the two. We investigate consequences of applying an outwardly directed magnetic force to a dilute suspension of magnetic microspheres circulating in a spiral microfluidic channel. This force is realized with an array of permanent magnets arranged to produce a magnetic field with octupolar symmetry about the spiral axis. At low flow rates particles cluster around an apparent streamline of the flow near the outer wall of the turn. At high flow rates this equilibrium is disrupted by the induced secondary (Dean) flow and a new equilibrium is established near the inner wall of the turn. A model incorporating key forces involved in establishing these equilibria is described, and is used to extract quantitative information about the magnitude of local Dean drag forces from experimental data. Steady-state fractionation of suspensions by particle size under the combined influence of magnetic and hydrodynamic forces is demonstrated. Extensions of this work could lead to new continuous microscale particle sorting and enrichment processes with improved fidelity and specificity. PMID:28107472

  3. Fractionation of Magnetic Microspheres in a Microfluidic Spiral: Interplay between Magnetic and Hydrodynamic Forces.

    PubMed

    Dutz, S; Hayden, M E; Häfeli, U O

    2017-01-01

    Magnetic forces and curvature-induced hydrodynamic drag have both been studied and employed in continuous microfluidic particle separation and enrichment schemes. Here we combine the two. We investigate consequences of applying an outwardly directed magnetic force to a dilute suspension of magnetic microspheres circulating in a spiral microfluidic channel. This force is realized with an array of permanent magnets arranged to produce a magnetic field with octupolar symmetry about the spiral axis. At low flow rates particles cluster around an apparent streamline of the flow near the outer wall of the turn. At high flow rates this equilibrium is disrupted by the induced secondary (Dean) flow and a new equilibrium is established near the inner wall of the turn. A model incorporating key forces involved in establishing these equilibria is described, and is used to extract quantitative information about the magnitude of local Dean drag forces from experimental data. Steady-state fractionation of suspensions by particle size under the combined influence of magnetic and hydrodynamic forces is demonstrated. Extensions of this work could lead to new continuous microscale particle sorting and enrichment processes with improved fidelity and specificity.

  4. Dual-Mode Encoded Magnetic Composite Microsphere Based on Fluorescence Reporters and Raman Probes as Covert Tag for Anticounterfeiting Applications.

    PubMed

    Li, Ruimin; Zhang, Yuting; Tan, Jing; Wan, Jiaxun; Guo, Jia; Wang, Changchun

    2016-04-13

    Utilizing fluorescence reporters and SERS probes as the security labels, a series of dual-mode encoded magnetic composite microspheres with micrometer size was designed and prepared for anticounterfeiting applications. At first, the micro-meter-sized melamine formaldehyde microspheres with different fluorescence molecules (FMF) were prepared by precipitation polymerization, and then the magnetite composite microspheres (FMF/MNPs) were fabricated by direct immobilization of magnetic nanoparticles (MNPs) onto the surface of FMF microspheres. After deposition of Ag nanoparticles (Ag-NPs) onto FMF/MNPs microspheres, the SERS probes were absorbed onto the surface of Ag-NPs, and then a protection layer of silica was coated on the composite microspheres by Stöber method. The combination of different fluorescence reporters and SERS probes greatly increased the encoding complexity and volume for high-level anticounterfeiting. The structure of the dual-encoded FMF/MNPs/Ag-NPs/SiO2 composite microspheres was characterized by FESEM, TEM, FLS(fluorescence spectrometer), XRD, VSM, UV-vis and EDS. The embedded magnetic nanoparticles enable the composite microspheres to be quickly isolated from the marked latex paint by magnet at the concentration of as low as 1 ppm, and the covert tag information can be read out even from one composite microsphere. In addition, the covert security information in the marked coating film can be also read out in situ and the existence of the composite microspheres does not influence the visible appearance of the coating film. All the above outstanding properties will make these dual-mode encoded composite microspheres as advanced security tags for next-generation anticounterfeiting applications.

  5. Magnetically separable and recyclable Fe3O4-polydopamine hybrid hollow microsphere for highly efficient peroxidase mimetic catalysts.

    PubMed

    Liu, Shujun; Fu, Jianwei; Wang, Minghuan; Yan, Ya; Xin, Qianqian; Cai, Lu; Xu, Qun

    2016-05-01

    Magnetic Fe3O4-polydopamine (PDA) hybrid hollow microspheres, in which Fe3O4 nanoparticles were firmly incorporated in the cross-linked PDA shell, have been prepared through the formation of core/shell PS/Fe3O4-PDA composites based on template-induced covalent assembly method, followed by core removal in a tetrahydrofuran solution. The morphology, composition, thermal property and magnetic property of the magnetic hybrid hollow microspheres were characterized by SEM, TEM, FT-IR, XRD, TGA, and vibrating sample magnetometer, respectively. Results revealed that the magnetic hybrid hollow microspheres had about 380 nm of inner diameter and about 30 nm of shell thickness, and 13.6 emu g(-1) of magnetization saturation. More importantly, the Fe3O4-PDA hybrid hollow microspheres exhibited intrinsic peroxidase-like activity, as they could quickly catalyze the oxidation of typical substrates 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide. Compared with PDA/Fe3O4 composites where Fe3O4 nanoparticles were loaded on the surface of PDA microspheres, the stability of Fe3O4-PDA hybrid hollow microspheres was greatly improved. As-prepared magnetic hollow microspheres might open up a new application field in biodetection, biocatalysis, and environmental monitoring. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

    NASA Astrophysics Data System (ADS)

    Magnet, C.; Kuzhir, P.; Bossis, G.; Meunier, A.; Nave, S.; Zubarev, A.; Lomenech, C.; Bashtovoi, V.

    2014-03-01

    When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, the size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in detail. In experiments, a dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50 μm) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces—the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter α ≥2), the Brownian motion seems not to affect the cloud behavior.

  7. Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields.

    PubMed

    Magnet, C; Kuzhir, P; Bossis, G; Meunier, A; Nave, S; Zubarev, A; Lomenech, C; Bashtovoi, V

    2014-03-01

    When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, the size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in detail. In experiments, a dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50 μm) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces-the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter α≥2), the Brownian motion seems not to affect the cloud behavior.

  8. Core–Shell Bimetallic Nanoparticles Robustly Fixed on the Outermost Surface of Magnetic Silica Microspheres

    PubMed Central

    Park, Hye Hun; Woo, Kyoungja; Ahn, Jae-Pyoung

    2013-01-01

    The major challenges in practically utilising the immense potential benefits of nanomaterials are controlling aggregation, recycling the nanomaterials, and fabricating well-defined nanoparticulate materials using innovative methods. We present a novel innovative synthetic strategy for core–shell bimetallic nanoparticles that are well-defined, ligand-free, and robustly fixed on the outermost surface of recyclable magnetic silica microspheres. The strategy includes seeding, coalescing the seeds to cores, and then growing shells from the cores on aminopropyl-functionalised silica microspheres so that the cores and aminopropyl moieties are robustly embedded in the shell materials. The representative Au–Ag bimetallic nanoparticles fixed on the microsphere showed excellent catalytic performance that remained consistent during repeated catalytic cycles. PMID:23511209

  9. Magnetic Microsphere-Based Methods to Study the Interaction of Teicoplanin with Peptides and Bacteria

    PubMed Central

    Piyasena, Menake E.; Real, Lilian J.; Diamond, Rochelle A.; Xu, H. Howard; Gomez, Frank A.

    2009-01-01

    Teicoplanin (teic) from Actinoplanes teichomyceticus is a glycopeptide antibiotic used to treat many gram-positive bacterial infections. Glycopeptide antibiotics inhibit the bacteria growth by binding to carboxy-terminal D-Ala-D-Ala intermediates in the peptidoglycan of cell wall of gram positive bacteria. In this paper we report the derivatization of magnetic microspheres with teic (teic-microspheres). Fluorescence based techniques have been developed to analyze the binding properties of the microspheres to two D-Ala-D-Ala terminus peptides. The dissociation constants for the binding of carboxyfluorescein labeled D-Ala-D-Ala-D-Ala to teic on microspheres is established via fluorometry and flow cytometry and was determined to be 0.5 × 10−6 and 3.0 × 10−6 M, respectively. Feasibility of utilizing microparticles with fluorescence methods to detect low levels (limit of bacterial detection was determined to be 200 colony forming units [cfu]) of gram-positive bacteria has been demonstrated. A simple microfluidic experiment is reported to demonstrate the possibility of developing microsphere based affinity assays to study peptide-antibiotic interaction. PMID:18712518

  10. Resonant magnetic response of TiO2 microspheres at terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Němec, H.; Kadlec, C.; Kadlec, F.; Kužel, P.; Yahiaoui, R.; Chung, U.-C.; Elissalde, C.; Maglione, M.; Mounaix, P.

    2012-02-01

    Spray-drying technique is used to fabricate spherical microparticles out of dissolved TiO2 nanoparticles. We show both experimentally and through numerical calculations that the microspheres support a Mie resonance, leading to an effective magnetic response. For this purpose, nearly single layers of microspheres were prepared and characterized by time-domain terahertz spectroscopy. We developed an experimental approach allowing simultaneous measurement of complex transmittance and reflectance of a thin layer, which in turn enables evaluation of its effective dielectric permittivity and effective magnetic permeability. Numerical finite-element-method calculations of the electromagnetic response show that the prepared microparticles are suitable for preparing a metamaterial with negative effective magnetic permeability.

  11. Templated synthesis of monodisperse mesoporous maghemite/silica microspheres for magnetic separation of genomic DNA

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Shi, Ruobing; Xue, Yun; Chen, Lei; Wan, Qian-Hong

    2010-08-01

    A novel method is described for the preparation of superparamagnetic mesoporous maghemite (γ-Fe 2O 3)/silica (SiO 2) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe 3O 4) and silica nanoparticles as starting materials, such microspheres were synthesized by the following two consecutive steps: (1) formation of monodispersed organic/inorganic hybrid microspheres through urea-formaldedyde (UF) polymerization and (2) removal of the organic template and phase transformation of Fe 3O 4 to γ-Fe 2O 3 by calcination at elevated temperatures. The as-synthesized particles obtained by heating at temperature 300 °C feature spherical shape and uniform particle size ( dparticle=1.72 μm), high saturation magnetization ( Ms=17.22 emu/g), superparamagnetism ( Mr/ Ms=0.023), high surface area ( SBET=240 m 2/g), and mesoporosity ( dpore=6.62 nm). The composite microsphere consists of interlocked amorphous SiO 2 nanoparticles, in which cubic γ-Fe 2O 3 nanocrystals are homogeneously dispersed and thermally stable against γ- to α-phase transformation at temperatures up to 600 °C. With the exposed iron oxide nanoparticles coated with a thin layer of silica shell, the magnetic microspheres were used as a solid-phase adsorbent for rapid extraction of genomic DNA from plant samples. The results show that the DNA templates isolated from pea and green pepper displayed single bands with molecular weights greater than 8 kb and A260/ A280 values of 1.60-1.72. The PCR amplification of a fragment encoding the endogenous chloroplast ndhB gene confirmed that the DNA templates obtained were inhibitor-free and amenable to sensitive amplification-based DNA technologies.

  12. Novel core-shell cerium(IV)-immobilized magnetic polymeric microspheres for selective enrichment and rapid separation of phosphopeptides.

    PubMed

    Wang, Zhi-Gang; Cheng, Gong; Liu, Yan-Lin; Zhang, Ji-Lin; Sun, De-Hui; Ni, Jia-Zuan

    2014-03-01

    In this work, novel magnetic polymeric core-shell structured microspheres with immobilized Ce(IV), Fe3O4@SiO2@PVPA-Ce(IV), were designed rationally and synthesized successfully via a facile route for the first time. Magnetic Fe3O4@SiO2 microspheres were first prepared by directly coating a thin layer of silica onto Fe3O4 magnetic particles using a sol-gel method, a poly(vinylphosphonic acid) (PVPA) shell was then coated on the Fe3O4@SiO2 microspheres to form Fe3O4@SiO2@PVPA microspheres through a radical polymerization reaction, and finally Ce(IV) ions were robustly immobilized onto the Fe3O4@SiO2@PVPA microspheres through strong chelation between Ce(IV) ions and phosphate moieties in the PVPA. The applicability of the Fe3O4@SiO2@PVPA-Ce(IV) microspheres for selective enrichment and rapid separation of phosphopeptides from proteolytic digests of standard and real protein samples was investigated. The results demonstrated that the core-shell structured Fe3O4@SiO2@PVPA-Ce(IV) microspheres with abundant Ce(IV) affinity sites and excellent magnetic responsiveness can effectively purify phosphopeptides from complex biosamples for MS detection taking advantage of the rapid magnetic separation and the selective affinity between Ce(IV) ions and phosphate moieties of the phosphopeptides. Furthermore, they can be effectively recycled and show good reusability, and have better performance than commercial TiO2 beads and homemade Fe3O4@PMAA-Ce(IV) microspheres. Thus the Fe3O4@SiO2@PVPA-Ce(IV) microspheres can benefit greatly the mass spectrometric qualitative analysis of phosphopeptides in phosphoproteome research.

  13. Angiogenic microspheres promote neural regeneration and motor function recovery after spinal cord injury in rats

    PubMed Central

    Yu, Shukui; Yao, Shenglian; Wen, Yujun; Wang, Ying; Wang, Hao; Xu, Qunyuan

    2016-01-01

    This study examined sustained co-delivery of vascular endothelial growth factor (VEGF), angiopoietin-1 and basic fibroblast growth factor (bFGF) encapsulated in angiogenic microspheres. These spheres were delivered to sites of spinal cord contusion injury in rats, and their ability to induce vessel formation, neural regeneration and improve hindlimb motor function was assessed. At 2–8 weeks after spinal cord injury, ELISA-determined levels of VEGF, angiopoietin-1, and bFGF were significantly higher in spinal cord tissues in rats that received angiogenic microspheres than in those that received empty microspheres. Sites of injury in animals that received angiogenic microspheres also contained greater numbers of isolectin B4-binding vessels and cells positive for nestin or β III-tubulin (P < 0.01), significantly more NF-positive and serotonergic fibers, and more MBP-positive mature oligodendrocytes. Animals receiving angiogenic microspheres also suffered significantly less loss of white matter volume. At 10 weeks after injury, open field tests showed that animals that received angiogenic microspheres scored significantly higher on the Basso-Beattie-Bresnahan scale than control animals (P < 0.01). Our results suggest that biodegradable, biocompatible PLGA microspheres can release angiogenic factors in a sustained fashion into sites of spinal cord injury and markedly stimulate angiogenesis and neurogenesis, accelerating recovery of neurologic function. PMID:27641997

  14. Enhanced Production of κ-Carrageenase and κ-Carrageenan Oligosaccharides through Immobilization of Thalassospira sp. Fjfst-332 with Magnetic Fe3O4-Chitosan Microspheres.

    PubMed

    Guo, Juanjuan; Zheng, Zhichang; Chen, Chi; Lu, Xu; Zhang, Yi; Zheng, Baodong

    2017-09-13

    In this study, immobilized bacteria (IMB) microsphere was prepared by embedding κ-carrageenase-producing Thalassospira sp. Fjfst-332 (TF332) onto a magnetic Fe3O4-chitosan carrier. The performance of Fe3O4-chitosan carrier was optimized by comparing its bacteria immobilization capacity at different Fe3O4:chitosan ratios and temperatures, while the functions of IMB microspheres were characterized by examining their κ-carrageenase production at different temperatures, pH's, and reuse cycles. At the 1:1 (w:w) Fe3O4:chitosan ratio, the Fe3O4-chitosan carriers possessed sufficient anchoring capacity for bacterial immobilization without significant compromise of their magnetism for magnetic separation of IMB from culture media. The spectroscopic analysis of IMB microspheres indicated that the immobilization of TF332 might affect the amide groups in chitosan. Compared to free bacteria, IMB can produce κ-carrageenase at higher temperature, wider pH range, and faster rate. More importantly, the κ-carrageenase-producing activity was sustained for at least seven reuse cycles. The major κ-carrageenan degradation products of IMB-derived κ-carrageenase were the oligosaccharides containing two to six monosaccharide units. Overall, this Fe3O4-chitosan-TF-332 microsphere has the potential to become a stable and reusable platform for large-scale production of κ-carrageenan oligosaccharides.

  15. Extraction of human genomic DNA from whole blood using a magnetic microsphere method.

    PubMed

    Gong, Rui; Li, Shengying

    2014-01-01

    With the rapid development of molecular biology and the life sciences, magnetic extraction is a simple, automatic, and highly efficient method for separating biological molecules, performing immunoassays, and other applications. Human blood is an ideal source of human genomic DNA. Extracting genomic DNA by traditional methods is time-consuming, and phenol and chloroform are toxic reagents that endanger health. Therefore, it is necessary to find a more convenient and efficient method for obtaining human genomic DNA. In this study, we developed urea-formaldehyde resin magnetic microspheres and magnetic silica microspheres for extraction of human genomic DNA. First, a magnetic microsphere suspension was prepared and used to extract genomic DNA from fresh whole blood, frozen blood, dried blood, and trace blood. Second, DNA content and purity were measured by agarose electrophoresis and ultraviolet spectrophotometry. The human genomic DNA extracted from whole blood was then subjected to polymerase chain reaction analysis to further confirm its quality. The results of this study lay a good foundation for future research and development of a high-throughput and rapid extraction method for extracting genomic DNA from various types of blood samples.

  16. Extraction of human genomic DNA from whole blood using a magnetic microsphere method

    PubMed Central

    Gong, Rui; Li, Shengying

    2014-01-01

    With the rapid development of molecular biology and the life sciences, magnetic extraction is a simple, automatic, and highly efficient method for separating biological molecules, performing immunoassays, and other applications. Human blood is an ideal source of human genomic DNA. Extracting genomic DNA by traditional methods is time‐consuming, and phenol and chloroform are toxic reagents that endanger health. Therefore, it is necessary to find a more convenient and efficient method for obtaining human genomic DNA. In this study, we developed urea–formaldehyde resin magnetic microspheres and magnetic silica microspheres for extraction of human genomic DNA. First, a magnetic microsphere suspension was prepared and used to extract genomic DNA from fresh whole blood, frozen blood, dried blood, and trace blood. Second, DNA content and purity were measured by agarose electrophoresis and ultraviolet spectrophotometry. The human genomic DNA extracted from whole blood was then subjected to polymerase chain reaction analysis to further confirm its quality. The results of this study lay a good foundation for future research and development of a high‐throughput and rapid extraction method for extracting genomic DNA from various types of blood samples. PMID:25143727

  17. Perfluoroalkyl-Functionalized Hyperbranched Polyglycerol as Pore Forming Agents and Supramolecular Hosts in Polymer Microspheres

    PubMed Central

    Wagner, Olaf; Zieringer, Maximilian; Duncanson, Wynter J.; Weitz, David A.; Haag, Rainer

    2015-01-01

    Perfluoroalkyl-functionalized, hyperbranched polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v). The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction. PMID:26343631

  18. Perfluoroalkyl-Functionalized Hyperbranched Polyglycerol as Pore Forming Agents and Supramolecular Hosts in Polymer Microspheres.

    PubMed

    Wagner, Olaf; Zieringer, Maximilian; Duncanson, Wynter J; Weitz, David A; Haag, Rainer

    2015-08-26

    Perfluoroalkyl-functionalized, hyperbranched polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v). The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction.

  19. Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres: Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres

    DOE PAGES

    Khromova, Irina; Kužel, Petr; Brener, Igal; ...

    2016-06-27

    Monocrystalline titanium dioxide (TiO2) micro-spheres support two orthogonal magnetic dipole modes at terahertz (THz) frequencies due to strong dielectric anisotropy. For the first time, we experimentally detected the splitting of the first Mie mode in spheres of radii inline imagem through near-field time-domain THz spectroscopy. By fitting the Fano lineshape model to the experimentally obtained spectra of the electric field detected by the sub-wavelength aperture probe, we found that the magnetic dipole resonances in TiO2 spheres have narrow linewidths of only tens of gigahertz. Lastly, anisotropic TiO2 micro-resonators can be used to enhance the interplay of magnetic and electric dipolemore » resonances in the emerging THz all-dielectric metamaterial technology.« less

  20. Synthesis and adsorption properties of hierarchical Fe3O4@MgAl-LDH magnetic microspheres

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoge; Li, Bo; Wen, Xiaogang

    2017-04-01

    In this study, Fe3O4 microspheres were prepared by a hydrothermal method, and then the synthesized Fe3O4 microspheres were used as template to prepare Fe3O4@MgAl-LDH composite microspheres by a coprecipitation process. Morphology, composition, and crystal structure of synthesized nanomaterials were characterized by X-ray powder diffractometry, scanning electron microscopy, and Fourier transform infrared spectroscopy technologies. The composite hierarchical microspheres are composed of inner Fe3O4 core and outer MgAl-LDH-nanoflake layer, and the average thickness of MgAl-LDH-nanoflake is about 70 nm. The adsorption property of the products toward congo red was also measured using UV-vis spectrometer. The result demonstrated that the Fe3O4@MgAl-LDH composite adsorbent could remove 99.8% congo red in 30 min, and the maximum adsorption capacity is about 404.6 mg/g, while congo red removal rate of pure MgAl-LDH and Fe3O4 are only 86.3 and 53.1% in 40 min, respectively, and their adsorption capacity are 345.72 and 220.56 mg/g, respectively. It indicates the composite Fe3O4@ MgAl-LDH nanomaterials have better adsorption performance than pure Fe3O4 and MgAl-LDH nanomaterials. In addition, the magnetic nanocomposites could be separated easily, and it demonstrated good cycle performance.

  1. CO2 Biofixation of Actinobacillus succinogenes Through Novel Amine-Functionalized Polystyrene Microsphere Materials.

    PubMed

    Zhu, Wenhao; Li, Qiang; Dai, Ning

    2017-02-01

    CO2-derived succinate production was enhanced by Actinobacillus succinogenes through polystyrene (PSt) microsphere materials for CO2 adsorption in bioreactor, and the adhesion forces between A. succinogenes bacteria and PSt materials were characterized. Synthesized uniformly sized and highly cross-linked PSt microspheres had high specific surface areas. After modification with amine functional groups, the novel amine-functionalized PSt microspheres exhibited a high adsorption capacity of 25.3 mg CO2/g materials. After addition with the functionalized microspheres into the culture broth, CO2 supply to the cells increased. Succinate production by A. succinogenes can be enhanced from 29.6 to 48.1 g L(-1). Moreover, the characterization of interaction forces between A. succinogenes cells and the microspheres indicated that the maximal adhesive force was about 250 pN. The amine-functionalized PSt microspheres can adsorb a large amount of CO2 and be employed for A. succinogenes anaerobic cultivation in bioreactor for high-efficiency production of CO2-derived succinate.

  2. Preparation of magnetic microspheres based on poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) copolymers by modified solvent diffusion method.

    PubMed

    Men, Ke; Zeng, Shi; Gou, MaLing; Guo, Gang; Gu, Ying Chun; Luo, Feng; Zhao, Xia; Wei, YuQuan; Qian, ZhiYong

    2010-06-01

    Magnetic microspheres have promising application in biomedical field. In this paper, biodegradable poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCEC) triblock copolymers were synthesized by ring-opening polymerization method. Through adjusting the epsilon-CL/PEG weight ratio in feed, PCEC copolymers with different block ratio were obtained. A novel modified solvent diffusion method was described to prepare magnetic PCEC composite microspheres containing magnetite nanoparticles. The particle size of microsphere decreased with increase in the PEG/PCL block ratio. The obtained microspheres could response to external magnetic field. This study described a novel method to prepare magnetic microspheres. The obtained magnetic polymeric microspheres might have potential application in drug delivery system or disease diagnosis field.

  3. Magnetic microspheres and tissue model studies for therapeutic applications

    NASA Technical Reports Server (NTRS)

    Ramachandran, Narayanan; Mazuruk, Konstantin

    2004-01-01

    The use of magnetic fluids and magnetic particles in combinatorial hyperthermia therapy for cancer treatment is reviewed. The investigation approach adopted for producing thermoregulating particles and tissue model studies for studying particle retention and heating characteristics is discussed.

  4. Magnetic microspheres and tissue model studies for therapeutic applications

    NASA Technical Reports Server (NTRS)

    Ramachandran, Narayanan; Mazuruk, Konstantin

    2004-01-01

    The use of magnetic fluids and magnetic particles in combinatorial hyperthermia therapy for cancer treatment is reviewed. The investigation approach adopted for producing thermoregulating particles and tissue model studies for studying particle retention and heating characteristics is discussed.

  5. γ-Fe2O3 and Fe3O4 magnetic hierarchically nanostructured hollow microspheres: preparation, formation mechanism, magnetic property, and application in water treatment.

    PubMed

    Xu, Jing-San; Zhu, Ying-Jie

    2012-11-01

    In this paper, we report the preparation of γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres by a solvothermal combined with precursor thermal conversion method. These γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres were constructed by three-dimensional self-assembly of nanosheets, forming porous nanostructures. The effects of experimental parameters including molar ratio of reactants and reaction temperature on the precursors were studied. The time-dependent experiments indicated that the Ostwald ripening was responsible for the formation of the hierarchically nanostructured hollow microspheres of the precursors. γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres were obtained by the thermal transformation of the precursor hollow microspheres. Both γ-Fe(2)O(3) and Fe(3)O(4) hierarchically nanostructured hollow microspheres exhibited a superparamagnetic property at room temperature and had the saturation magnetization of 44.2 and 55.4 emu/g, respectively, in the applied magnetic field of 20 KOe. Several kinds of organic pollutants including salicylic acid (SA), methylene blue (MB), and basic fuchsin (BF) were chosen as the model water pollutants to evaluate the removal abilities of γ-Fe(2)O(3) and Fe(3)O(4) magnetic hierarchically nanostructured hollow microspheres. It was found that γ-Fe(2)O(3) hierarchically nanostructured hollow microspheres showed a better adsorption ability over SA than MB and BF. However, Fe(3)O(4) hierarchically nanostructured hollow microspheres had the best performance for adsorbing MB. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Hyperemic stress myocardial perfusion cardiovascular magnetic resonance in mice at 3 Tesla: initial experience and validation against microspheres.

    PubMed

    Jogiya, Roy; Makowski, Markus; Phinikaridou, Alkystsis; Patel, Ashish S; Jansen, Christian; Zarinabad, Niloufar; Chiribiri, Amedeo; Botnar, Rene; Nagel, Eike; Kozerke, Sebastian; Plein, Sven

    2013-07-21

    Dynamic first pass contrast-enhanced myocardial perfusion is the standard CMR method for the estimation of myocardial blood flow (MBF) and MBF reserve in man, but it is challenging in rodents because of the high temporal and spatial resolution requirements. Hyperemic first pass myocardial perfusion CMR during vasodilator stress in mice has not been reported. Five C57BL/6 J mice were scanned on a clinical 3.0 Tesla Achieva system (Philips Healthcare, Netherlands). Vasodilator stress was induced via a tail vein catheter with an injection of dipyridamole. Dynamic contrast-enhanced perfusion imaging (Gadobutrol 0.1 mmol/kg) was based on a saturation recovery spoiled gradient echo method with 10-fold k-space and time domain undersampling (k-t PCA). One week later the mice underwent repeat anaesthesia and LV injections of fluorescent microspheres at rest and at stress. Microspheres were analysed using confocal microscopy and fluorescence-activated cell sorting. Mean MBF at rest measured by Fermi-function constrained deconvolution was 4.1 ± 0.5 ml/g/min and increased to 9.6 ± 2.5 ml/g/min during dipyridamole stress (P = 0.005). The myocardial perfusion reserve was 2.4 ± 0.54. The mean count ratio of stress to rest microspheres was 2.4 ± 0.51 using confocal microscopy and 2.6 ± 0.46 using fluorescence. There was good agreement between cardiovascular magnetic resonance CMR and microspheres with no significant difference (P = 0.84). First-pass myocardial stress perfusion CMR in a mouse model is feasible at 3 Tesla. Rest and stress MBF values were consistent with existing literature and perfusion reserve correlated closely to microsphere analysis. Data were acquired on a 3 Tesla scanner using an approach similar to clinical acquisition protocols, potentially facilitating translation of imaging findings between rodent and human studies.

  7. Hyperemic stress myocardial perfusion cardiovascular magnetic resonance in mice at 3 Tesla: initial experience and validation against microspheres

    PubMed Central

    2013-01-01

    Background Dynamic first pass contrast-enhanced myocardial perfusion is the standard CMR method for the estimation of myocardial blood flow (MBF) and MBF reserve in man, but it is challenging in rodents because of the high temporal and spatial resolution requirements. Hyperemic first pass myocardial perfusion CMR during vasodilator stress in mice has not been reported. Methods Five C57BL/6 J mice were scanned on a clinical 3.0 Tesla Achieva system (Philips Healthcare, Netherlands). Vasodilator stress was induced via a tail vein catheter with an injection of dipyridamole. Dynamic contrast-enhanced perfusion imaging (Gadobutrol 0.1 mmol/kg) was based on a saturation recovery spoiled gradient echo method with 10-fold k-space and time domain undersampling (k-t PCA). One week later the mice underwent repeat anaesthesia and LV injections of fluorescent microspheres at rest and at stress. Microspheres were analysed using confocal microscopy and fluorescence-activated cell sorting. Results Mean MBF at rest measured by Fermi-function constrained deconvolution was 4.1 ± 0.5 ml/g/min and increased to 9.6 ± 2.5 ml/g/min during dipyridamole stress (P = 0.005). The myocardial perfusion reserve was 2.4 ± 0.54. The mean count ratio of stress to rest microspheres was 2.4 ± 0.51 using confocal microscopy and 2.6 ± 0.46 using fluorescence. There was good agreement between cardiovascular magnetic resonance CMR and microspheres with no significant difference (P = 0.84). Conclusion First-pass myocardial stress perfusion CMR in a mouse model is feasible at 3 Tesla. Rest and stress MBF values were consistent with existing literature and perfusion reserve correlated closely to microsphere analysis. Data were acquired on a 3 Tesla scanner using an approach similar to clinical acquisition protocols, potentially facilitating translation of imaging findings between rodent and human studies. PMID:23870734

  8. Facile preparation of multifunctional uniform magnetic microspheres for T1-T2 dual modal magnetic resonance and optical imaging.

    PubMed

    Zhang, Li; Liang, Shuang; Liu, Ruiqing; Yuan, Tianmeng; Zhang, Shulai; Xu, Zushun; Xu, Haibo

    2016-08-01

    Molecular imaging is of significant importance for early detection and diagnosis of cancer. Herein, a novel core-shell magnetic microsphere for dual modal magnetic resonance imaging (MRI) and optical imaging was produced by one-pot emulsifier-free emulsion polymerization, which could provide high resolution rate of histologic structure information and realize high sensitive detection at the same time. The synthesized magnetic microspheres composed of cores containing oleic acid (OA) and sodium undecylenate (NaUA) modified Fe3O4 nanoparticles and styrene (St), Glycidyl methacrylate (GMA), and polymerizable lanthanide complexes (Gd(AA)3Phen and Eu(AA)3Phen) polymerized on the surface for outer shells. Fluorescence spectra show characteristic emission peaks from Eu(3+) at 590nm and 615nm and vivid red fluorescence luminescence can be observed by 2-photon confocal scanning laser microscopy (CLSM). In vitro cytotoxicity tests based on the MTT assay demonstrate good cytocompatibility, the composites have longitudinal relaxivity value (r1) of 8.39mM(-1)s(-1) and also have transverse relaxivity value (r2) of 71.18mM(-1)s(-1) at clinical 3.0 T MR scanner. In vitro and in vivo MRI studies exhibit high signal enhancement on both T1- and T2-weighted MR images. These fascinating multifunctional properties suggest that the polymer microspheres have large clinical potential as multi-modal MRI/optical probes. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  9. Magnetic separation of micro-spheres from viscous biological fluids.

    PubMed

    Chen, Haitao; Kaminski, Michael D; Caviness, Patricia L; Liu, Xianqiao; Dhar, Promila; Torno, Michael; Rosengart, Axel J

    2007-02-21

    A magnetically based detoxification system is being developed as a therapeutic tool for selective and rapid removal of biohazards, i.e. chemicals and radioactive substances, from human blood. One of the key components of this system is a portable magnetic separator capable of separating polymer-based magnetic nano/micro-spheres from arterial blood flow in an ex vivo unit. The magnetic separator consists of an array of alternating and parallel capillary tubing and magnetizable wires, which is exposed to an applied magnetic field created by two parallel permanent magnets such that the magnetic field is perpendicular to both the wires and the fluid flow. In this paper, the performance of this separator was evaluated via preliminary in vitro flow experiments using a separator unit consisting of single capillary glass tubing and two metal wires. Pure water, ethylene glycol-water solution (v:v=39:61 and v:v=49:51) and human whole blood were used as the fluids. The results showed that when the viscosity increased from 1.0 cp to 3.0 cp, the capture efficiency (CE) decreased from 90% to 56%. However, it is still feasible to obtain >90% CE in blood flow if the separator design is optimized to create higher magnetic gradients and magnetic fields in the separation area.

  10. Determination of the functional space for fluid movement in the rat dentinal tubules using fluorescent microsphere.

    PubMed

    Li, Ying; Ikeda, Hideharu; Suda, Hideaki

    2013-07-01

    The size of the functional space available for hydrodynamic fluid movement between cellular components and the walls of dentinal tubules has not yet been investigated. We attempted to measure the space using small diameter fluorescent microspheres. The coronal enamel of 144 rat molars was removed to expose the dentine, which was acid-etched. Fluorescent microspheres of different diameters (0.02-4.0μm) were applied to the exposed dentine for 60min before the rat jaws were cut into cryostat sections. The distribution and fluorescent intensities of the fluorescent microspheres were examined with confocal laser scanning microscope and analyzed using image analysis software. Microspheres with a diameter of 2.0-4.0μm were detected only on the surface of the cavities. A small number of microspheres with a diameter of 1.0μm accumulated primarily in the outer third of the dentine. Microspheres with a diameter of 0.2-0.5μm were found in the outer and middle thirds of the dentine. Microspheres with a diameter of 0.02-0.1μm accumulated in the middle and occasionally inner thirds of the dentine. Some of the microspheres measuring 0.02-0.04μm in diameter reached the dental pulp. The dentinal tubules in the inner third of the rat coronal dentine may have a space less than 0.1μm through which dentinal fluid can move, despite outward tapering of the dentinal tubules. Retrograde tapering may increase the pressure in the inner third of the dentine layer, and this elevated pressure may contribute to mechanical deformation of the content in the dentinal tubules. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Alzheimer's disease biomarkers detection in human samples by efficient capturing through porous magnetic microspheres and labelling with electrocatalytic gold nanoparticles.

    PubMed

    de la Escosura-Muñiz, Alfredo; Plichta, Zdeněk; Horák, Daniel; Merkoçi, Arben

    2015-05-15

    A nanobiosensor based on the use of porous magnetic microspheres (PMM) as efficient capturing/pre-concentrating platform is presented for detection of Alzheimer's disease (AD) biomarkers. These PMMs prepared by a multistep swelling polymerization combined with iron oxide precipitation afford carboxyl functional groups suitable for immobilization of antibodies on the particle surface allowing an enhanced efficiency in the capturing of AD biomarkers from human serum samples. The AD biomarkers signaling is produced by gold nanoparticle (AuNP) tags monitored through their electrocatalytic effect towards hydrogen evolution reaction (HER). Novel properties of PMMs in terms of high functionality and high active area available for enhanced catalytic activity of the captured AuNPs electrocatalytic tags are exploited for the first time. A thorough characterization by scanning transmission electron microscope in high angle annular dark field mode (STEM-HAADF) demonstrates the enhanced ability of PMMs to capture a higher quantity of analyte and consequently of electrocatalytic label, when compared with commercially available microspheres. The optimized and characterized PMMs are also applied for the first time for the detection of beta amyloid and ApoE at clinical relevant levels in cerebrospinal fluid (CSF), serum and plasma samples of patients suffering from AD. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Zirconium-doped magnetic microspheres for the selective enrichment of cis-diol-containing ribonucleosides.

    PubMed

    Fan, Hua; Chen, Peihong; Wang, Chaozhan; Wei, Yinmao

    2016-05-27

    Zirconium-doped magnetic microspheres (Zr-Fe3O4) for the selective enrichment of cis-diol-containing biomolecules were easily synthesized via a one-step hydrothermal method. Characterization of the microspheres revealed that zirconium was successfully doped into the lattice of Fe3O4 at a doping level of 4.0 at%. Zr-Fe3O4 possessed good magnetic properties and high specificity towards cis-diol molecules, as shown using 28 compounds. For ribonucleosides, the adsorbent not only has favorable anti-interferential abilities but also has a high adsorption capacity up to 159.4μmol/g. As an example of a real application, four ribonucleosides in urine were efficiently enriched and detected via magnetic solid-phase extraction coupled with high-performance liquid chromatography. Under the optimized extraction conditions, the detection limits were determined to be between 0.005 and 0.017μg/mL, and the linearities ranged from 0.02 to 5.00μg/mL (R≥0.996) for these analytes. The accuracy of the analytical method was examined by studying the relative recoveries of the analytes in real urine samples, with recoveries varying from 77.8% to 119.6% (RSDs<10.6%, n=6). The results indicate that Zr-Fe3O4 is a suitable adsorbent for the analysis of cis-diol-containing biomolecules in practical applications.

  13. Magnetic Microspheres and Tissue Model Studies for Therapeutical Applications

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Mazuruk, K.

    2003-01-01

    Hyperthermia is a well known cancer therapy and consists of heating a tumor region to the elevated temperatures in the range of 40-45 C for an extended period of time (2-8 hours). This leads to thermal inactivation of cell regulatory and growth processes with resulting widespread necrosis, carbonization and coagulation. Moreover, heat boosts the tumor response to other treatments such as radiation, chemotherapy or immunotherapy. Of particular importance is careful control of generated heat in the treated region and keeping it localized. Higher heating, to about 56 C can lead to tissue thermo-ablation. With accurate temperature control, hyperthermia has the advantage of having minimal side effects. Several heating techniques are utilized for this purpose, such as whole body hyperthermia, radio-frequency (RF) hyperthermia, ultrasound technique, inductive microwave antenna hyperthermia, inductive needles (thermoseeds), and magnetic fluid hyperthermia (MFH).MFH offers many advantages as targeting capability by applying magnets. However, this technology still suffers significant inefficiencies due to lack of thermal control. This paper will provide a review of the topic and outline the ongoing work in this area. The main emphasis is in devising ways to overcome the technical difficulty in hyperthermia breast therapy of achieving a uniform therapeutic temperature over the required region of the body and holding it steady for an extended period (2-3 hours). The basic shortcomings of the presently utilized heating methods stem from the non-uniform thermal properties of the tissue and the point heating characteristics of the techniques without any thermal control. Our approach is to develop a novel class of magnetic fluids, which have inherent thermoregulating properties. We have identified a few magnetic alloys which can serve as suitable nano to micron-size particle material. The objective is to synthesize, characterize and evaluate the efficacy of Thermo Regulating

  14. Magnetic Microspheres and Tissue Model Studies for Therapeutical Applications

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Mazuruk, K.

    2003-01-01

    Hyperthermia is a well known cancer therapy and consists of heating a tumor region to the elevated temperatures in the range of 40-45 C for an extended period of time (2-8 hours). This leads to thermal inactivation of cell regulatory and growth processes with resulting widespread necrosis, carbonization and coagulation. Moreover, heat boosts the tumor response to other treatments such as radiation, chemotherapy or immunotherapy. Of particular importance is careful control of generated heat in the treated region and keeping it localized. Higher heating, to about 56 C can lead to tissue thermo-ablation. With accurate temperature control, hyperthermia has the advantage of having minimal side effects. Several heating techniques are utilized for this purpose, such as whole body hyperthermia, radio-frequency (RF) hyperthermia, ultrasound technique, inductive microwave antenna hyperthermia, inductive needles (thermoseeds), and magnetic fluid hyperthermia (MFH).MFH offers many advantages as targeting capability by applying magnets. However, this technology still suffers significant inefficiencies due to lack of thermal control. This paper will provide a review of the topic and outline the ongoing work in this area. The main emphasis is in devising ways to overcome the technical difficulty in hyperthermia breast therapy of achieving a uniform therapeutic temperature over the required region of the body and holding it steady for an extended period (2-3 hours). The basic shortcomings of the presently utilized heating methods stem from the non-uniform thermal properties of the tissue and the point heating characteristics of the techniques without any thermal control. Our approach is to develop a novel class of magnetic fluids, which have inherent thermoregulating properties. We have identified a few magnetic alloys which can serve as suitable nano to micron-size particle material. The objective is to synthesize, characterize and evaluate the efficacy of Thermo Regulating

  15. Magnetorheology of xanthan-gum-coated soft magnetic carbonyl iron microspheres and their polishing characteristics

    NASA Astrophysics Data System (ADS)

    Kwon, Seung Hyuk; Choi, Hyoung Jin; Lee, Jung Won; Hong, Kwang Pyo; Cho, Myeong Woo

    2013-06-01

    Magnetorheological (MR) fluids are colloidal suspensions of soft magnetic particles dispersed in a non-magnetic liquid. Among their applications, MR polishing has attracted considerable attention owing to its smart control of the polishing characteristics for dedicated microelectromechanical system applications. To improve the polishing characteristics of MR fluids, we fabricated carbonyl iron (CI) microspheres coated with xanthan gum (XG) by using a solvent casting method. The morphologies and densities of both pure CI and CI/XG particles were characterized using a scanning electron microscope and a pycnometer, respectively. In addition, the rheological characteristics of the MR fluids under various applied magnetic field strengths were examined using a rotational rheometer. The MR polishing characteristics were conducted using an MR polishing machine to examine the surface roughness and the material removal by MR polishing with added nano-ceria slurry abrasives.

  16. Activation of the Solid Silica Layer of Aerosol-Based C/SiO₂ Particles for Preparation of Various Functional Multishelled Hollow Microspheres.

    PubMed

    Li, Xiangcun; Luo, Fan; He, Gaohong

    2015-05-12

    Double-shelled C/SiO2 hollow microspheres with an outer nanosheet-like silica shell and an inner carbon shell were reported. C/SiO2 aerosol particles were synthesized first by a one-step rapid aerosol process. Then the solid silica layer of the aerosol particles was dissolved and regrown on the carbon surface to obtain novel C/SiO2 double-shelled hollow microspheres. The new microspheres prepared by the facile approach possess high surface area and pore volume (226.3 m(2) g(-1), 0.51 cm(3) g(-1)) compared with the original aerosol particles (64.3 m(2) g(-1), 0.176 cm(3) g(-1)), providing its enhanced enzyme loading capacity. The nanosheet-like silica shell of the hollow microspheres favors the fixation of Au NPs (C/SiO2/Au) and prevents them from growing and migrating at 500 °C. Novel C/C and C/Au/C (C/Pt/C) hollow microspheres were also prepared based on the hollow nanostructure. C/C microspheres (482.0 m(2) g(-1), 0.92 cm(3) g(-1)) were ideal electrode materials. In particular, the Au NPs embedded into the two carbon layers (C/Au/C, 431.2 m(2) g(-1), 0.774 cm(3) g(-1)) show a high catalytic activity and extremely chemical stability even at 850 °C. Moreover, C/SiO2/Au, C/Au/C microspheres can be easily recycled and reused by an external magnetic field because of the presence of Fe3O4 species in the inner carbon shell. The synthetic route reported here is expected to simplify the fabrication process of double-shelled or yolk-shell microspheres, which usually entails multiple steps and a previously synthesized hard template. Such a capability can facilitate the preparation of various functional hollow microspheres by interfacial design.

  17. Processing and size range separation of pristine and magnetic poly(l-lactic acid) based microspheres for biomedical applications.

    PubMed

    Correia, D M; Sencadas, V; Ribeiro, C; Martins, P M; Martins, P; Gama, F M; Botelho, G; Lanceros-Méndez, S

    2016-08-15

    Biodegradable poly(l-lactic acid) (PLLA) and PLLA/CoFe2O4 magnetic microspheres with average sizes ranging between 0.16-3.9μm and 0.8-2.2μm, respectively, were obtained by an oil-in-water emulsion method using poly(vinyl alcohol) (PVA) solution as the emulsifier agent. The separation of the microspheres in different size ranges was then performed by centrifugation and the colloidal stability assessed at different pH values. Neat PLLA spheres are more stable in alkaline environments when compared to magnetic microspheres, both types being stable for pHs higher than 4, resulting in a colloidal suspension. On the other hand, in acidic environments the microspheres tend to form aggregates. The neat PLLA microspheres show a degree of crystallinity of 40% whereas the composite ones are nearly amorphous (17%). Finally, the biocompatibility was assessed by cell viability studies with MC3T3-E1 pre-osteoblast cells.

  18. Facile Synthesis of Porous Nickel/Carbon Composite Microspheres with Enhanced Electromagnetic Wave Absorption by Magnetic and Dielectric Losses.

    PubMed

    Qiu, Song; Lyu, Hailong; Liu, Jiurong; Liu, Yuzhen; Wu, Nannan; Liu, Wei

    2016-08-10

    Porous nickel/carbon (Ni/C) composite microspheres with diameters of ca. 1.2-1.5 μm were fabricated by a solvothermal method combined with carbon reduction. The pore size of the synthesized Ni/C composite microspheres ranged from several nanometers to 50 nm. The porous Ni/C composite microspheres exhibited a saturation magnetization (MS) of 53.5 emu g(-1) and a coercivity (HC) of 51.4 Oe. When tested as an electromagnetic (EM) wave absorption material, the epoxy resin composites containing 60% and 75% porous Ni/C microspheres provided high-performance EM wave absorption at thicknesses of 3.0-11.0 and 1.6-7.0 mm in the corresponding frequency ranges of 2.0-12 and 2.0-18 GHz, respectively. The superior EM wave absorption performances of porous Ni/C composite microspheres were derived from the synergy effects generated by the magnetic loss of nickel, the dielectric loss of carbon, and the porous structure.

  19. Biodiesel production in a magnetically-stabilized, fluidized bed reactor with an immobilized lipase in magnetic chitosan microspheres.

    PubMed

    Zhou, Gui-Xiong; Chen, Guan-Yi; Yan, Bei-Bei

    2014-01-01

    Biodiesel production by immobilized Rhizopus oryzae lipase in magnetic chitosan microspheres (MCMs) was carried out using soybean oil and methanol in a magnetically-stabilized, fluidized bed reactor (MSFBR). The maximum content of methyl ester in the reaction mixture reached 91.3 (w/v) at a fluid flow rate of 25 ml/min and a magnetic field intensity of 150 Oe. In addition, the MCMs-immobilized lipase in the reactor showed excellent reusability, retaining 82 % productivity even after six batches, which was much better than that in a conventional fluidized bed reactor. These results suggested that a MSFRB using MCMs-immobilized lipase is a promising method for biodiesel production.

  20. Evaluation of a magnetic microsphere antibody detection assay for the investigation of exposure to Cryptosporidium parvum and Cryptosporidium hominis

    EPA Science Inventory

    Anti-Cryptosporidium IgA and IgG are useful markers of exposure to Cryptosporidium in human populations, but detection in saliva may be difficult. To evaluate a magnetic microsphere assay for detection of anti-Cryptosporidium IgA and IgG in saliva, recombinant sporozoite gp15 (1...

  1. Pulsatile drug release from PLGA hollow microspheres by controlling the permeability of their walls with a magnetic field.

    PubMed

    Chiang, Wei-Lun; Ke, Cherng-Jyh; Liao, Zi-Xian; Chen, San-Yuan; Chen, Fu-Rong; Tsai, Chun-Ying; Xia, Younan; Sung, Hsing-Wen

    2012-12-07

    Pulsatile release: When a high-frequency magnetic field is applied, heat will be generated by coupling to the iron oxide nanoparticles encapsulated in the shells of PLGA hollow microspheres. As the temperature approaches the T(g) of PLGA, the polymer chains become more mobile, subsequently increasing the free volume of PLGA matrix and significantly enhancing the diffusion of drug molecules.

  2. Phase-transitional Fe3O4/perfluorohexane Microspheres for Magnetic Droplet Vaporization

    PubMed Central

    Wang, Ronghui; Zhou, Yang; Zhang, Ping; Chen, Yu; Gao, Wei; Xu, Jinshun; Chen, Hangrong; Cai, Xiaojun; Zhang, Kun; Li, Pan; Wang, Zhigang; Hu, Bing; Ying, Tao; Zheng, Yuanyi

    2017-01-01

    Activating droplets vaporization has become an attractive strategy for ultrasound imaging and physical therapy due to the significant increase in ultrasound backscatter signals and its ability to physically damage the tumor cells. However, the current two types of transitional droplets named after their activation methods have their respective limitations. To circumvent the limitations of these activation methods, here we report the concept of magnetic droplet vaporization (MDV) for stimuli-responsive cancer theranostics by a magnetic-responsive phase-transitional agent. This magnetic-sensitive phase-transitional agent—perfluorohexane (PFH)-loaded porous magnetic microspheres (PFH-PMMs), with high magnetic-thermal energy-transfer capability, could quickly respond to external alternating current (AC) magnetic fields to produce thermal energy and trigger the vaporization of the liquid PFH. We systematically demonstrated MDV both in vitro and in vivo. This novel trigger method with deep penetration can penetrate the air-filled viscera and trigger the vaporization of the phase-transitional agent without the need of pre-focusing lesion. This unique MDV strategy is expected to substantially broaden the biomedical applications of nanotechnology and promote the clinical treatment of tumors that are not responsive to chemical therapies. PMID:28382158

  3. Preparation and characterization of PHBV microsphere/45S5 bioactive glass composite scaffolds with vancomycin releasing function.

    PubMed

    Li, Wei; Ding, Yaping; Rai, Ranjana; Roether, Judith A; Schubert, Dirk W; Boccaccini, Aldo R

    2014-08-01

    PHBV microsphere/45S5 bioactive glass (BG) composite scaffolds with drug release function were developed for bone tissue engineering. BG-based glass-ceramic scaffolds with high porosity (94%) and interconnected pore structure prepared by foam replication method were coated with PHBV microspheres (nominal diameter=3.5 μm) produced by water-in-oil-in-water double emulsion solvent evaporation method. A homogeneous microsphere coating throughout the porous structure of scaffolds was obtained by a simple dip coating method, using the slurry of PHBV microspheres in hexane. Compressive strength tests showed that the microsphere coating slightly improved the mechanical properties of the scaffolds. It was confirmed that the microsphere coating did not inhibit the bioactivity of the scaffolds in SBF. Hydroxyapatite crystals homogeneously grew not only on the struts of the scaffolds but also on the surface of microspheres within 7 days of immersion in SBF. Vancomycin was successfully encapsulated into the PHBV microspheres. The encapsulated vancomycin was released with a dual release profile involving a relatively low initial burst release (21%) and a sustained release (1 month), which is favorable compared to the high initial burst release (77%) and short release period (4 days) measured on uncoated scaffolds. The developed bioactive composite scaffold with drug delivery function has thus the potential to be used advantageously in bone tissue engineering.

  4. Self-construction of magnetic hollow La0.7Sr0.3MnO3 microspheres with complex units.

    PubMed

    Chu, Xuefeng; Huang, Keke; Han, Mei; Feng, Shouhua

    2013-04-15

    Perovskite structure La0.7Sr0.3MnO3 magnetic hollow microspheres with complex units were prepared via the hydrothermal route without hard and soft templates. The formation of hollow microspheres follows the self-construction mechanism involving oriented attachment, dissolution, and recrystallization processes. It exhibits a ferromagnetic behavior at room temperature.

  5. Sequestration, fluorometric detection, and mass spectroscopy analysis of lanthanide ions using surface modified magnetic microspheres for microfluidic manipulation.

    SciTech Connect

    Shkrob, I. A.; Kaminski, M. D.; Mertz, C. J.; Rickert, P. G.; Derzon, M. S.; Rahimian, K.; Chemical Sciences and Engineering Division; SNL

    2009-11-04

    Several methods for rapid sequestration, fluorometric detection, and the subsequent mass spectroscopic analysis of lanthanide ions using surface modified polystyrene magnetic microspheres are demonstrated. Mixed-ligand antenna complexes of Eu{sup 3+} in which one of the ligands is attached to the surface of the microspheres have been used as a means for the sequestration, immobilization, and detection of these ions. Using the ion-exchange properties of these microspheres, this scheme has been extended to the detection of nonluminescent ions. The principles of these assays form the basis for operation of a portable microfluidic device for general analytical and nuclear forensics applications and indicate the manner in which the established methods of analytical chemistry, such as liquid-liquid extraction and ion-exchange chromatography, can be adapted for such miniature devices.

  6. Magnetically directed poly(lactic acid) [sup 90]Y-microspheres: Novel agents for targeted intracavitary radiotherapy

    SciTech Connect

    Haefeli, U.O.; Sweeney, S.M.; Beresford, B.A.; Sim, E.H.; Macklis, R.M. . Joint Center for Radiation Therapy)

    1994-08-01

    High energy [beta]-emitting radioisotopes like Yttrium-90 have a radiotoxic range of about one centimeter. For cancer treatment they must be brought near the tumor cells and kept there for as long as they are radioactive. The authors developed as carriers for the ionic form of [sup 90]Y a matrix-type polymeric drug delivery system, poly(lactic acid) (PLA) microspheres. This radiopharmaceutical could be selectively delivered to the target site after incorporating 10% Fe[sub 3]O[sub 4] which made the magnetic microspheres (MMS) responsive to an external magnetic field. Furthermore, MMS are biodegradable and slowly hydrolyze into physiologic lactic acid after the radioactivity is completely decayed. Previously prepared 10--40 [mu]m MMS were radiochemically loaded to high specific activity with [sup 90]Y at a pH of 5.7. Stability studies showed that approximately 95% of added [sup 90]Y is retained within the PLA matrix after 28 days (> 10 half-lives) at 37 C in serum, and electron microscopy showed that the microspheres retained their characteristic morphologic appearance for the same time period. Cytotoxicity studies with SK-N-SH neuroblastoma cells growing in monolayer showed that the radiocytotoxicity of the microspheres could be directed magnetically to either kill or spare specific cell populations, thus making them of great interest for targeted intracavitary tumor therapy. The authors are currently optimizing this system for use in the treatment of neoplastic meningitis.

  7. Synthesis of magnetic epichlorohydrin cross-linked carboxymethyl cellulose microspheres and their adsorption behavior for methylene blue.

    PubMed

    Lin, Qingwen; Chang, Jiali; Gao, Mengfan; Ma, Hongzhu

    2017-01-28

    Epichlorohydrin cross-linked carboxymethyl cellulose microspheres (ECH/CMC) obtained by inverse suspension method and magnetic Fe3O4 nanoparticles encasing the ECH/CMC microspheres (M-ECH/CMC) obtained by two different methods were successfully prepared and compared. Their structures and morphologies were analyzed using polarizing microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The adsorption behaviors of M1-ECH/CMC for methylene blue (MB) in the single cationic dye wastewater, the cationic/anionic dye mixture in the absence or presence of co-existed additives (salt and surfactant) wastewater, were also investigated with UV-vis spectrometer. The results showed that the magnetic Fe3O4 nanoparticles were loaded readily in situ into ECH/CMC by specific, chemical interactions between COO(-) groups of ECH/CMC and magnetic responsive Fe3O4. The Langmuir isotherm and pseudo-second-order kinetic model provide best correlation with the experimental data for the adsorption of MB onto ECH/CMC and M1-ECH/CMC microspheres, while the Langmuir isotherm and pseudo-first-order kinetic model for M2-ECH/CMC. These microspheres are easily recyclable and exhibit high desorption and adsorption, which suggests that they can be applied as potential environmental adsorbents.

  8. Immobilization of penicillin G acylase in epoxy-activated magnetic cellulose microspheres for improvement of biocatalytic stability and activities.

    PubMed

    Luo, Xiaogang; Zhang, Lina

    2010-11-08

    We prepared magnetic cellulose porous microspheres (MCM) with mean diameter of ∼200 μm by employing the sol-gel transition (SGT) method from a mixture of magnemite ferrofluid and cellulose dissolved in 7 wt % NaOH/12% urea aqueous solvent precooled to -12 °C. Subsequently, the cellulose microspheres were activated with epoxy chloropropane to enhance loading efficiency of biomacromolecules. Their morphology, structure, and properties were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and vibrating-sample magnetometer. The results indicated that the spherical magnetic γ-Fe2O3 nanoparticles with mean size of 10 nm were uniformly dispersed and embedded in the cellulose substrate of MCM, and the structure and nature of γ-Fe2O3 were conserved perfectly. Penicillin G acylase (PGA) as a biocatalyst was immobilized successfully in the porous microspheres, as a result of the existence of the cavity and affinity forces in the activated cellulose matrix. The immobilized PGA exhibited highly effective catalytic activity, thermal stability, and enhanced tolerance to pH variations. Furthermore, the cellulose microspheres loaded with the enzymes could be removed and recovered easily by introducing a magnetic field, leading to an acceptable reusability. Therefore, we have provided a simple and biocompatible support for the enzyme immobilization, which will be promising for the applications in the biomaterial fields.

  9. PREPARATION OF FLOWER-LIKE Co3O4/Fe3O4 MAGNETIC MICROSPHERES FOR PHOTODEGRADATION OF RhB UNDER UV LIGHT

    NASA Astrophysics Data System (ADS)

    Zhang, Baoliang; Zhang, Hepeng; Zhou, Lunwei; Ali, Nisar; Geng, Wangchang; Zhang, Qiuyu

    2013-07-01

    Flower-like Co3O4/Fe3O4 magnetic microspheres were prepared by coprecipitation of Fe2+ and Fe3+ in presence of flower-like Co3O4 microspheres as template. The preparation process included three steps: preparation of flower-like Co3O4 microspheres by hydrothermal method; immersion of Fe2+ and Fe3+ ions; coprecipitation in the presence of OH-. Rhodamine B (RhB) was chosen as model pollutants to investigate the photodegradation capacities of Co3O4/Fe3O4 magnetic microspheres. The results showed that the microspheres exhibited excellent degradation property and can be recycled to use again. After four times use the degradation efficiency was still above 90%.

  10. Synergetic integration of laccase and versatile peroxidase with magnetic silica microspheres towards remediation of biorefinery wastewater.

    PubMed

    Vishnu, Dhanya; Neeraj, Gerard; Swaroopini, Ramachandran; Shobana, Ravi; Kumar, Vaidyanathan Vinoth; Cabana, Hubert

    2017-06-17

    In this study, a tailor-made biocatalyst consisting of a co-immobilized lignolytic enzyme cascade on multi-functionalized magnetic silica microspheres (MSMS) was developed. Physical adsorption was the most promising strategy for the synthesis of individual immobilized laccase (IL), immobilized versatile peroxidase (IP), as well as co-immobilized laccase (Lac) and versatile peroxidase (VP) with an enzyme activity recovery of about 79, 93, 27, and 27.5%, respectively. Similarly, the biocatalytic load of 116, 183, 23.6, and 31 U/g was obtained for IL, IP, and co-immobilized Lac and VP, respectively. The co-immobilized enzyme system exhibited better pH stability than the free and individual immobilized system by retaining more than 100% residual activity at pH 7.0 after a 150-h incubation; whereas, the thermal stability and kinetics of the co-immobilized biocatalyst were not much improved. IL and IP could be recycled for 10 cycles after which they retained 31 and 44% of their initial activities. Co-immobilized Lac and VP were reused for ten consecutive cycles at the end of which Lac activity was depleted, and 37% of VP activity was left. Free enzymes, IL, IP, co-immobilized Lac, and VP were applied to biorefinery wastewater (BRW) in a batch study to investigate the transformation of phenolic contaminants over a period of 5 days. The major classes of phenolic constituents in terms of their order of removal in a Lac-VP system was phenol >2-chlorophenol > trichlorophenol > dichlorophenol > cresols > dimethylphenol >2 methyl- 4, 6-dinitrophenol > 4-nitrophenol > tetrachlorophenols > pentachlorophenol. The free enzymes and individually immobilized enzymes resulted in 80% dephenolization in 5 days. By contrast, the co-immobilized biocatalyst provided rapid dephenolization yielding the same 80% removal within 24 h and 96% removal of phenols in 60 h after which the system stabilized, which is the major advantage of the co-immobilized biocatalyst. ᅟ Graphical abstract.

  11. Development of microwave-assisted protein digestion based on trypsin-immobilized magnetic microspheres for highly efficient proteolysis followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis.

    PubMed

    Lin, Shuang; Lin, Zhenxin; Yao, Guoping; Deng, Chunhui; Yang, Pengyuan; Zhang, Xiangmin

    2007-01-01

    In this study, very easily prepared trypsin-immobilized magnetic microspheres were applied in microwave-assisted protein digestion and firstly applied for proteome analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Magnetic microspheres with small size were synthesized and modified by 3-glycidoxypropyltrimethoxysilane (GLYMO). Trypsin was immobilized onto magnetic microspheres through only a one-step reaction of its amine group with GLYMO. When these easily prepared trypsin-immobilized magnetic microspheres were applied in microwave-assisted protein digestion, the magnetic microspheres not only functionalized as substrate for trypsin immobilization, but also as an excellent microwave absorber and thus improved the efficiency of microwave-assisted digestion greatly. Cytochrome c was used as a model protein to verify its digestion efficiency. Without any additives such as organic solvents or urea, peptide fragments produced in 15 s could be confidently identified by MALDI-TOF-MS and better digestion efficiency was obtained comparing to conventional in-solution digestion (12 h). Besides, with an external magnet, trypsin could be used repeatedly and at the same time no contaminants were introduced into the sample solution. It was verified that the enzyme maintained high activity after seven runs. Furthermore, reversed-phase liquid chromatography (RPLC) fractions of rat liver extract were also successfully processed using this novel method. These results indicated that this fast and efficient digestion method, which combined the advantages of immobilized trypsin and microwave-assisted protein digestion, will greatly hasten the application of top-down proteomic techniques for large-scale analysis in biological and clinical research.

  12. Polymeric microspheres

    DOEpatents

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  13. Studies in the Use of Magnetic Microspheres for Immunoaffinity Extraction of Paralytic Shellfish Poisoning Toxins from Shellfish

    PubMed Central

    Devlin, Raymond; Campbell, Katrina; Kawatsu, Kentaro; Elliott, Christopher

    2011-01-01

    Paralytic shellfish poisoning (PSP) is a potentially fatal human health condition caused by the consumption of shellfish containing high levels of PSP toxins. Toxin extraction from shellfish and from algal cultures for use as standards and analysis by alternative analytical monitoring methods to the mouse bioassay is extensive and laborious. This study investigated whether a selected MAb antibody could be coupled to a novel form of magnetic microsphere (hollow glass magnetic microspheres, brand name Ferrospheres-N) and whether these coated microspheres could be utilized in the extraction of low concentrations of the PSP toxin, STX, from potential extraction buffers and spiked mussel extracts. The feasibility of utilizing a mass of 25 mg of Ferrospheres-N, as a simple extraction procedure for STX from spiked sodium acetate buffer, spiked PBS buffer and spiked mussel extracts was determined. The effects of a range of toxin concentrations (20-300 ng/mL), incubation times and temperature on the capability of the immuno-capture of the STX from the spiked mussel extracts were investigated. Finally, the coated microspheres were tested to determine their efficiency at extracting PSP toxins from naturally contaminated mussel samples. Toxin recovery after each experiment was determined by HPLC analysis. This study on using a highly novel immunoaffinity based extraction procedure, using STX as a model, has indicated that it could be a convenient alternative to conventional extraction procedures used in toxin purification prior to sample analysis. PMID:22069687

  14. Fabrication of High-Performance Magnetic Lysozyme-Imprinted Microsphere and Its NIR-Responsive Controlled Release Property.

    PubMed

    Chen, Jinxing; Lei, Shan; Xie, Yunyun; Wang, Mozhen; Yang, Jun; Ge, Xuewu

    2015-12-30

    The preparation of efficient and practical biomacromolecules imprinted polymer materials is still a challenging task because of the spatial hindrance caused by the large size of template and target molecules in the imprinting and recognition process. Herein, we provided a novel pathway to coat a NIR-light responsive lysozyme-imprinted polydopamine (PDA) layer on a fibrous SiO2 (F-SiO2) microsphere grown up from a magnetic Fe3O4 core nanoparticle. The magnetic core-shell structured lysozyme-imprinted Fe3O4@F-SiO2@PDA microspheres (MIP-lysozyme) can be easily separated by a magnet and have a high saturation adsorption capacity of lysozyme of 700 mg/g within 30 min because of the high surface area of 570 m(2)/g and the mesopore size of 12 nm of the Fe3O4@F-SiO2 support. The MIP-lysozyme microspheres also show an excellent selective adsorption of lysozyme (IF > 4). The binding thermodynamic parameters studied by ITC proves that the lysozyme should be restricted by the well-defined 3D structure of MIP-lysozyme microspheres. The MIP-lysozyme can extract lysozyme efficiently from real egg white. Owing to the efficient NIR light photothermal effect of PDA layer, the MIP-lysozyme microspheres show the controlled release property triggered by NIR laser. The released lysozyme molecules still maintain good bioactivity, which can efficiently decompose E. coli. Therefore, this work provides a novel strategy to build practical NIR-light-responsive MIPs for the extraction and application of biomacromolecules.

  15. Prostaglandin D2-loaded microspheres effectively activate macrophage effector functions.

    PubMed

    Pereira, Priscilla Aparecida Tartari; Bitencourt, Claudia da Silva; dos Santos, Daiane Fernanda; Nicolete, Roberto; Gelfuso, Guilherme Martins; Faccioli, Lúcia Helena

    2015-10-12

    Biodegradable lactic-co-glycolic acid (PLGA) microspheres (MS) improve the stability of biomolecules stability and allow enable their sustained release. Lipid mediators represent a strategy for improving host defense; however, most of these mediators, such as prostaglandin D2 (PGD2), have low water solubility and are unstable. The present study aimed to develop and characterize MS loaded with PGD2 (PGD2-MS) to obtain an innovative tool to activate macrophages. PGD2-MS were prepared using an oil-in-water emulsion solvent extraction-evaporation process, and the size, zeta potential, surface morphology and encapsulation efficiency were determined. It was also evaluated in vitro the phagocytic index, NF-κB activation, as well as nitric oxide and cytokine production by alveolar macrophages (AMs) in response to PGD2-MS. PGD2-MS were spherical with a diameter of 5.0±3.3 μm and regular surface, zeta potential of -13.4±5.6 mV, and 36% of encapsulation efficiency, with 16-26% release of entrapped PGD2 at 4 and 48 h, respectively. PGD2-MS were more efficiently internalized by AMs than unloaded-MS, and activated NF-κB more than free PGD2. Moreover, PGD2-MS stimulated the production of nitric oxide, TNF-α, IL-1β, and TGF-β, more than free PGD2, indicating that microencapsulation increased the activating effect of PGD2 on cells. In LPS-pre-treated AMs, PGD2-MS decreased the release of IL-6 but increased the production of nitric oxide and IL-1β. These results show that the morphological characteristics of PGD2-MS facilitated interaction with, and activation of phagocytic cells; moreover, PGD2-MS retained the biological activities of PGD2 to trigger effector mechanisms in AMs. It is suggested that PGD2-MS represent a strategy for therapeutic intervention in the lungs of immunocompromised subjects.

  16. An Interface Coassembly in Biliquid Phase: Toward Core-Shell Magnetic Mesoporous Silica Microspheres with Tunable Pore Size.

    PubMed

    Yue, Qin; Li, Jialuo; Luo, Wei; Zhang, Yu; Elzatahry, Ahmed A; Wang, Xiqing; Wang, Chun; Li, Wei; Cheng, Xiaowei; Alghamdi, Abdulaziz; Abdullah, Aboubakr M; Deng, Yonghui; Zhao, Dongyuan

    2015-10-21

    Core-shell magnetic mesoporous silica microspheres (Magn-MSMs) with tunable large mesopores in the shell are highly desired in biocatalysis, magnetic bioseparation, and enrichment. In this study, a shearing assisted interface coassembly in n-hexane/water biliquid systems is developed to synthesize uniform Magn-MSMs with magnetic core and mesoporous silica shell for an efficient size-selective biocatalysis. The synthesis features the rational control over the electrostatic interaction among cationic surfactant molecules, silicate oligomers, and Fe3O4@RF microspheres (RF: resorcinol formaldehyde) in the presence of shearing-regulated solubilization of n-hexane in surfactant micelles. Through this multicomponent interface coassembly, surfactant-silica mesostructured composite has been uniformly deposited on the Fe3O4@RF microspheres, and core-shell Magn-MSMs are obtained after removing the surfactant and n-hexane. The obtained Magn-MSMs possess excellent water dispersibility, uniform diameter (600 nm), large and tunable perpendicular mesopores (5.0-9.0 nm), high surface area (498-623 m(2)/g), large pore volume (0.91-0.98 cm(3)/g), and high magnetization (34.5-37.1 emu/g). By utilization of their large and open mesopores, Magn-MSMs with a pore size of about 9.0 nm have been demonstrated to be able to immobilize a large bioenzyme (trypsin with size of 4.0 nm) with a high loading capacity of ∼97 μg/mg via chemically binding. Magn-MSMs with immobilized trypsin exhibit an excellent convenient and size selective enzymolysis of low molecular proteins in the mixture of proteins of different sizes and a good recycling performance by using the magnetic separability of the microspheres.

  17. Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Voos, Avery; Pelphrey, Kevin

    2013-01-01

    Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

  18. Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Voos, Avery; Pelphrey, Kevin

    2013-01-01

    Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

  19. Superconducting combined function magnets

    SciTech Connect

    Hahn, H.; Fernow, R.C.

    1983-01-01

    Superconducting accelerators and storage rings, presently under construction or in the design phase, are based on separate dipole and quadrupole magnets. It is here suggested that a hybrid lattice configuration consisting of dipoles and combined function gradient magnets would: (1) reduce the number of magnet units and their total cost; and (2) increase the filling factor and thus the energy at a given field. Coil cross sections are presented for the example of the Brookhaven Colliding Beam Accelerator. An asymmetric two-layer cable gradient magnet would have transfer functions of 10.42 G/A and 0.628 G cm/sup -1//A versus 15.77 G/A and 2.03 G cm/sup -1//A of the present separate dipoles and quadrupoles.

  20. Water-compatible magnetic imprinted microspheres for rapid separation and determination of triazine herbicides in environmental water.

    PubMed

    Qiao, Fengxia; Row, Kyung Ho; Wang, Mengge

    2014-04-15

    A novel kind of water-compatible magnetic imprinted cyromazine microsphere (WCMM) was synthesized by water/oil/water suspension polymerization. The obtained WCMM was homogenously spherical with porous morphology and strong magnetic properties. The microspheres were successfully used as adsorbent in dispersive solid-phase extraction (WCMM-dSPE) to selectively extract cyanazine and atrazine from environmental water. Good linearity of the two analytes was observed in the range from 2.5 to 200.0ngmL(-1). The average recoveries at three spiking levels ranged from 84.8% to 104.3% with relative standard deviations (RSD) less than 6.9%. Compared with magnetic non-imprinted particles (WCMN), the proposed WCMM adsorbent of dSPE efficiently improved the efficiency of extracting cyanazine and atrazine from environmental water samples and eliminated the effect of cyromazine leakage on the quantitative analysis of cyanazine and atrazine. The proposed WCMM-dSPE method combined the advantages of magnetic separation, molecular imprinted microspheres and dSPE. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Highly reusability surface loaded metal particles magnetic catalyst microspheres (MCM-MPs) for treatment of dye-contaminated water

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Zhang, Kun; Yin, Xiaoshuang; Yang, Wenzhong; Zhu, Hongjun

    2016-04-01

    The metal-deposited magnetic catalyst microspheres (MCM-MPs) were successfully synthesized by one facile, high yield and controllable approach. Here, the bare magnetic microspheres were firstly synthesized according to the solvothermal method. Then silica shell were coated on the surface of the magnetic microspheres via sol-gel method, and subsequently with surface modifying with amino in the purpose to form SiO2-NH2 shell. Thus, metal particles were easily adsorbed into the SiO2-NH2 shell and in-situ reduced by NaBH4 solution. All the obtained products (MCM-Cu, MCM-Ag, MCM-Pd) which were monodisperse and constitutionally stable were exhibited high magnetization and excellent catalytic activity towards dyes solution reduction. The catalytic rate ratio of MCM-Pd: MCM-Cu: MCM-Ag could be 10:3:1. Besides, some special coordination compound Cu2(OH)3Br had been generated in the in-situ reduced process of MCM-Cu, which produced superior cyclical stability (>20 times) than that of MCM-Ag and MCM-Pd. In all, those highly reusability and great catalytic efficiency of MCM-MPs show promising and great potential for treatment of dye-contaminated water.

  2. Functionalized bridged silsesquioxane-based nanostructured microspheres: performance as novel drug-delivery devices in bone tissue-related applications.

    PubMed

    Romeo, Hernán Esteban; Fanovich, María Alejandra

    2012-05-01

    Two kinds of functionalized nanostructured hybrid microspheres, based on the bridged silsesquioxane family, were synthesized by employing the sol-gel method via self-assembly of two different organic-inorganic bridged monomers. The architecture reached at molecular level allowed the incorporation of acetylsalicylic acid (ASA) as an anti-inflammatory model drug. The ASA-functionalized microspheres were characterized as delivery devices in simulated body fluid (SBF). The release behaviors of the synthesized microspheres (Fickian or anomalous diffusion mechanisms) were shown to be dependent on the chemical nature of the bridged monomers employed to synthesize the hybrid materials. The functionalized microspheres were proposed as delivery systems into calcium phosphate cements (CPCs), in order to slow down the characteristic drug-delivery kinetics of this kind of bone tissue-related materials. The incorporation of the new functionalized microparticles into the CPCs represented a viable methodology to modify the ASA-release kinetics in comparison to a conventional CPC containing the drug dispersed into the solid phase. The ASA-delivery profiles obtained from the microsphere-loaded CPCs showed that 40-60% of drug can be released after 2 weeks of testing in SBF. The inclusion of the microspheres into the CPC matrices allowed modification of the release profiles through a mechanism that involved two stages: (1) the diffusion of the drug through the organic-inorganic matrix of the microspheres (according to a Fickian or anomalous diffusion, depending on the nanostructuring) and (2) the subsequent diffusion of the drug through the ceramic matrix of the hardened cements. The release behavior of the composite cements was shown to be dependent on the nanostructuring of the hybrid microspheres, which can be selectively tailored by choosing the desired chemical structure of the bridged precursors employed in the sol-gel synthesis. The obtained results demonstrated the ability of

  3. Functional polymeric microspheres based on 2-hydroxyethyl methacrylate for immunochemical studies

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Yen, S. P. S.; Cheong, E.; Wallace, S.; Molday, R. S.; Gordon, I. L.; Dreyer, W. J.

    1976-01-01

    Co gamma irradiation of 2-hydroxyethyl methacrylate in the presence or in the absence of other acrylic monomers was found to constitute an effective technique for the synthesis of hydrophilic functional microspheres in the size range of approximately 0.3 to 3 microns in diameter. The effect of monomer concentration, steric stabilization, and electrostatic interaction on the particle size was investigated. Experimental conditions were determined to obtain desired particle sizes of relatively narrow distribution. It was shown that particles may be formed without intermediate micelles, i.e., by homogeneous nucleation, and the rate of particle formation is affected primarily by the rate of particle coalescence in the initial stages of the reaction. When covalently bound to antibodies these microspheres were successfully used to label murine and human lymphocytes.

  4. Functional polymeric microspheres based on 2-hydroxyethyl methacrylate for immunochemical studies

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Yen, S. P. S.; Cheong, E.; Wallace, S.; Molday, R. S.; Gordon, I. L.; Dreyer, W. J.

    1976-01-01

    Co gamma irradiation of 2-hydroxyethyl methacrylate in the presence or in the absence of other acrylic monomers was found to constitute an effective technique for the synthesis of hydrophilic functional microspheres in the size range of approximately 0.3 to 3 microns in diameter. The effect of monomer concentration, steric stabilization, and electrostatic interaction on the particle size was investigated. Experimental conditions were determined to obtain desired particle sizes of relatively narrow distribution. It was shown that particles may be formed without intermediate micelles, i.e., by homogeneous nucleation, and the rate of particle formation is affected primarily by the rate of particle coalescence in the initial stages of the reaction. When covalently bound to antibodies these microspheres were successfully used to label murine and human lymphocytes.

  5. Synthesis and characterization of dual-functionalized core-shell fluorescent microspheres for bioconjugation and cellular delivery.

    PubMed

    Behrendt, Jonathan M; Nagel, David; Chundoo, Evita; Alexander, Lois M; Dupin, Damien; Hine, Anna V; Bradley, Mark; Sutherland, Andrew J

    2013-01-01

    The efficient transport of micron-sized beads into cells, via a non-endocytosis mediated mechanism, has only recently been described. As such there is considerable scope for optimization and exploitation of this procedure to enable imaging and sensing applications to be realized. Herein, we report the design, synthesis and characterization of fluorescent microsphere-based cellular delivery agents that can also carry biological cargoes. These core-shell polymer microspheres possess two distinct chemical environments; the core is hydrophobic and can be labeled with fluorescent dye, to permit visual tracking of the microsphere during and after cellular delivery, whilst the outer shell renders the external surfaces of the microspheres hydrophilic, thus facilitating both bioconjugation and cellular compatibility. Cross-linked core particles were prepared in a dispersion polymerization reaction employing styrene, divinylbenzene and a thiol-functionalized co-monomer. These core particles were then shelled in a seeded emulsion polymerization reaction, employing styrene, divinylbenzene and methacrylic acid, to generate orthogonally functionalized core-shell microspheres which were internally labeled via the core thiol moieties through reaction with a thiol reactive dye (DY630-maleimide). Following internal labeling, bioconjugation of green fluorescent protein (GFP) to their carboxyl-functionalized surfaces was successfully accomplished using standard coupling protocols. The resultant dual-labeled microspheres were visualized by both of the fully resolvable fluorescence emissions of their cores (DY630) and shells (GFP). In vitro cellular uptake of these microspheres by HeLa cells was demonstrated conventionally by fluorescence-based flow cytometry, whilst MTT assays demonstrated that 92% of HeLa cells remained viable after uptake. Due to their size and surface functionalities, these far-red-labeled microspheres are ideal candidates for in vitro, cellular delivery of proteins.

  6. Fast and efficient proteolysis by microwave-assisted protein digestion using trypsin-immobilized magnetic silica microspheres.

    PubMed

    Lin, Shuang; Yao, Guoping; Qi, Dawei; Li, Yan; Deng, Chunhui; Yang, Pengyuan; Zhang, Xiangmin

    2008-05-15

    A fast and efficient proteolysis approach of microwave-assisted protein digestion was developed by using trypsin-immobilized magnetic silica (MS) microspheres. In the work, immobilization of the enzyme onto MS microspheres was very simple and only through a one-step reaction with 3-glycidoxypropyltrimethoxysilane (GLYMO) which provides the epoxy group as a reactive spacer. Considering that the magnetic particles are excellent microwave absorbers, we developed a novel microwave-assisted digestion method based on the easily prepared trypsin-immobilized MS microspheres. This novel digestion method combined the advantages of immobilized trypsin and the rapid-fashion of microwave-assisted digestion, which resulted in high digestion efficiency. BSA and myoglobin were used as model proteins to optimize the conditions of this method. Peptide fragments produced in 15 s could be confidently identified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. Equivalent or better digestion efficiency was observed comparing to current in-solution digestion. Besides, because of the unique magnetic responsivity, the immobilized trypsin can be isolated easily with the help of an external magnet and thus used repeatedly. High activity was obtained even after seven runs of the trypsin-immobilized MS microspheres. To further verify its efficiency in proteome analysis, one reversed-phase liquid chromatography (RPLC) fraction of rat liver extract was applied. After 15 s incubation, 16 totally unique peptides corresponding to two proteins were identified. Finally, the rat liver sample was used to evaluate its worth for the application. With analysis by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS), comparable digestion efficiency was observed with typical in-solution digestion but the incubation time was largely shortened. This new microwave-assisted digestion method will hasten the application of the proteome

  7. Polyethylenimine-interlayered core-shell-satellite 3D magnetic microspheres as versatile SERS substrates

    NASA Astrophysics Data System (ADS)

    Wang, Chongwen; Li, Ping; Wang, Junfeng; Rong, Zhen; Pang, Yuanfeng; Xu, Jiawen; Dong, Peitao; Xiao, Rui; Wang, Shengqi

    2015-11-01

    Precise fabrication of subtle nanogaps amid individual nanoparticles or between adjacent ones to obtain the highest SERS enhancement is still a challenge. Here, we reported a novel approach for fabricating core-shell-satellite 3D magnetic microspheres (CSSM), that easily form a porous 1.5 nm PEI interlayer to accommodate molecules and create sufficient hotspots between the inner Fe3O4@Ag core and outer assembled Au@Ag satellites. Experiments and finite-difference time-domain (FDTD) simulation demonstrated that the enhancement factor (EF) was about 2.03 × 108 and 6.25 × 106, respectively. In addition, the micro-scale magnetic core endowed the CSSM with a superior magnetic nature, which enabled easy separation and further enhanced Raman signals due to enrichment of targeted analytes and abundant interparticle hotspots created by magnetism-induced aggregation. Our results further demonstrated that the CSSM is expected to be a versatile SERS substrate, which has been verified by the detection of the adsorbed pesticide thiram and the non-adsorbed pesticide paraquat with a detection limit as low as 5 × 10-12 M and 1 × 10-10 M, respectively. The novel CSSM can overcome the long-standing limitations of SERS for the trace characterization of various analytes in different solutions and promises to transform SERS into a practical analytical technique.Precise fabrication of subtle nanogaps amid individual nanoparticles or between adjacent ones to obtain the highest SERS enhancement is still a challenge. Here, we reported a novel approach for fabricating core-shell-satellite 3D magnetic microspheres (CSSM), that easily form a porous 1.5 nm PEI interlayer to accommodate molecules and create sufficient hotspots between the inner Fe3O4@Ag core and outer assembled Au@Ag satellites. Experiments and finite-difference time-domain (FDTD) simulation demonstrated that the enhancement factor (EF) was about 2.03 × 108 and 6.25 × 106, respectively. In addition, the micro

  8. Magnetic Carbon Microspheres as a Reusable Adsorbent for Sulfonamide Removal from Water

    NASA Astrophysics Data System (ADS)

    Dai, Kewei; Wang, Fenghe; Jiang, Wei; Chen, Yajun; Mao, Jing; Bao, Jian

    2017-09-01

    Novel reusable magnetic carbon microspheres (MCMs) were prepared by hydrothermal method with glucose as carbon source and Fe3O4 nanoparticles as magnetic raw materials. And adsorption performance of MCMs for sulfonamide removal from water was investigated in detail. The results indicated that the calcination temperature and calcination time had significant effects on the surface area and its volume porous of MCMs. When MCMs were calcined in 600 °C for 1 h, the surface area and volume porous of MCMs were 1228 m2/g and 0.448 m3/g, respectively. The adsorption results showed that the adsorption data fitted well with the Langmuir isotherm model and followed pseudo-second-order kinetics. When the pH value was changed from 4.0 to 10.0, the adsorption capacity of MCMs for sulfonamide was decreased from 24.6 to 19.2 mg/g. The adsorption capacity of as-synthesized MCMs achieved 18.31 mg/g after it was reused four times, which exhibited a desirable adsorption capacity and reusability.

  9. Hydrophilic porous magnetic poly(GMA-MBAA-NVP) composite microspheres containing oxirane groups: An efficient carrier for immobilizing penicillin G acylase

    NASA Astrophysics Data System (ADS)

    Xue, Ping; Su, Weiguang; Gu, Yaohua; Liu, Haifeng; Wang, Julan

    2015-03-01

    Magnetic hydrophilic polymeric microspheres containing oxirane groups were prepared by inverse suspension polymerization of glycidyl methacrylate (GMA), N, N‧-methylene bisacrylamide (MBAA) and N-vinyl pyrrolidone (NVP) in the existence of formamide, which were denoted as magnetic poly(GMA-MBAA-NVP) microspheres. The magnetic poly(GMA-MBAA-NVP) microspheres were characterized by scanning electron microscopy (SEM), FT-IR spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. The results showed that poly(GMA-MBAA-NVP) microspheres possessed well spherical shape, narrow size distribution, abundant porous structure, reactive oxirane groups and superparamagnetic properties. Formamide used in the present work served as a modifier, a dispersant and a porogen to form final porous polymer microspheres. The penicillin G acylase (PGA) was covalently immobilized onto the magnetic microspheres through the reaction between the amino groups of enzyme and the oxirane groups on the microspheres for producing 6-aminopenicillanic acid (6-APA). The effects of GMA/NVP ratio and crosslink density on the activity of immobilized PGA were investigated. The highest apparent activity, enzyme loading and coupling yield of immobilized PGA were 821 IU/g, 65.3 mg/g and 42.3% respectively when the mass ratio of GMA/NVP was 1:1 and crosslink density was 60%. Compared with the free PGA, immobilized PGA showed a wider range of pH value and reaction temperature. The relative activity and reaction rate of immobilized PGA remained almost constant after 20 recycles. The magnetic poly(GMA-MBAA-NVP) microspheres would be very promising carriers for immobilizing enzymes in industrial application.

  10. Amine-functionalized magnetic mesoporous silica nanoparticles for DNA separation

    NASA Astrophysics Data System (ADS)

    Sheng, Wei; Wei, Wei; Li, Junjian; Qi, Xiaoliang; Zuo, Gancheng; Chen, Qi; Pan, Xihao; Dong, Wei

    2016-11-01

    We report a modified approach for the functionalized magnetic mesoporous silica nanoparticles (MMSN) using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) and the core-shell magnetic silica nanoparticles (MSN). These particles were functionalized with amino groups via the addition of aminosilane directly to the particle sol. We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased (210.22 μg/mg) compared with normal magnetic silica spheres (138.44 μg/mg) by using an ultraviolet and visible spectrophotometer (UV). The morphologies, magnetic properties, particle size, pore size, core-shell structure and Zeta potential are characterized by Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM), Powder X-ray diffraction (XRD), and dynamic light scattering (DLS). This work demonstrates that our MMSN own an excellent potential application in bioseparation and drug delivery.

  11. Aminosilanized magnetic carbon microspheres for the magnetic solid-phase extraction of bisphenol A, bisphenol AF. and tetrabromobisphenol A from environmental water samples.

    PubMed

    Gong, Sheng-Xiang; Wang, Xiao-Li; Liu, Wei; Wang, Ming-Lin; Wang, Xia; Wang, Zheng-Wu; Zhao, Ru-Song

    2017-02-20

    Aminosilanized magnetic carbon microspheres as a novel adsorbent were designed and fabricated. And the adsorbent was used for the magnetic solid-phase extraction of bisphenols at trace levels from environmental water samples before liquid chromatography with tandem mass spectrometry analysis. The structure, surface and magnetic behavior of the as-prepared aminosilanized magnetic carbon microspheres were characterized by elemental analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, and vibrating sample magnetometry. The effects of the experimental parameters were investigated by the Plackett-Burman design, and then the parameters that were significant to the extraction efficiencies were optimized through a response surface methodology. The aminosilanized magnetic carbon microspheres exhibited high adsorption efficiency and selectivity for bisphenols. Under optimal conditions, low limits of detection (0.011-2.22 ng·L(-1) ), and a wide linear range (2-3 orders of magnitude), good repeatability (4.7-7.8%, n = 5) and reproducibility (6.0-8.3%, n = 3) were achieved. The results demonstrate that the novel adsorbent possesses great potentials in the determination of trace levels of bisphenols in environmental water samples. This article is protected by copyright. All rights reserved.

  12. Magnetic-luminescent YbPO4:Er,Dy microspheres designed for tumor theranostics with synergistic effect of photodynamic therapy and chemotherapy.

    PubMed

    Wang, Wei; Xu, Dong; Wei, Xiaojun; Chen, Kezheng

    2014-01-01

    In this paper, magnetic and fluorescent bifunctional YbPO4:Er,Dy microspheres were synthesized via a simple solvothermal method. The prepared microspheres exposed to 980 nm near-infrared (NIR) laser light emitted bright upconversion fluorescence (450-570 nm) after calcination at high temperatures (>800°C). Results of magnetic resonance studies demonstrated that the YbPO4:Er,Dy microspheres are more suitable to be used as a transverse relaxation time (negative) contrast magnetic resonance imaging agent. The microspheres successfully entered the human hepatocellular carcinoma cells and presented low toxicity. A well-selected photodynamic therapy (PDT) drug, merocyanine 540 (MC540) with an ultraviolet-visible spectroscopy absorption maximum of 540 nm, was loaded onto the microspheres to obtain YbPO4:Er,Dy-MC540. Since the upconversion fluorescence emitting from the microspheres could be absorbed by MC540 with a small absorption/emission disparity, YbPO4:Er,Dy-MC540 could kill the hepatocellular carcinoma cells via PDT mechanism effectively. In other words, being upconverting particles, the prepared microspheres acted as light transducers in the NIR light-triggered PDT process. A chemotherapy drug, doxorubicin, was further loaded onto YbPO4:Er,Dy-MC540 to achieve enhanced antitumor effect based on synergistic therapeutic efficacy of PDT and chemotherapy. It is expected that the prepared YbPO4:Er,Dy microspheres have applications in tumor theranostics including magnetic-fluorescent bimodal imaging and NIR light-triggered PDT.

  13. Magnetic-luminescent YbPO4:Er,Dy microspheres designed for tumor theranostics with synergistic effect of photodynamic therapy and chemotherapy

    PubMed Central

    Wang, Wei; Xu, Dong; Wei, Xiaojun; Chen, Kezheng

    2014-01-01

    In this paper, magnetic and fluorescent bifunctional YbPO4:Er,Dy microspheres were synthesized via a simple solvothermal method. The prepared microspheres exposed to 980 nm near-infrared (NIR) laser light emitted bright upconversion fluorescence (450–570 nm) after calcination at high temperatures (>800°C). Results of magnetic resonance studies demonstrated that the YbPO4:Er,Dy microspheres are more suitable to be used as a transverse relaxation time (negative) contrast magnetic resonance imaging agent. The microspheres successfully entered the human hepatocellular carcinoma cells and presented low toxicity. A well-selected photodynamic therapy (PDT) drug, merocyanine 540 (MC540) with an ultraviolet–visible spectroscopy absorption maximum of 540 nm, was loaded onto the microspheres to obtain YbPO4:Er,Dy-MC540. Since the upconversion fluorescence emitting from the microspheres could be absorbed by MC540 with a small absorption/emission disparity, YbPO4:Er,Dy-MC540 could kill the hepatocellular carcinoma cells via PDT mechanism effectively. In other words, being upconverting particles, the prepared microspheres acted as light transducers in the NIR light-triggered PDT process. A chemotherapy drug, doxorubicin, was further loaded onto YbPO4:Er,Dy-MC540 to achieve enhanced antitumor effect based on synergistic therapeutic efficacy of PDT and chemotherapy. It is expected that the prepared YbPO4:Er,Dy microspheres have applications in tumor theranostics including magnetic-fluorescent bimodal imaging and NIR light-triggered PDT. PMID:25364246

  14. Simple and efficient synthesis of copper(II)-modified uniform magnetic Fe3O4@SiO2 core/shell microspheres for immobilization of cellulase

    NASA Astrophysics Data System (ADS)

    Li, Shi-Kuo; Hou, Xiao-Cheng; Huang, Fang-Zhi; Li, Chuan-Hao; Kang, Wen-Juan; Xie, An-Jian; Shen, Yu-Hua

    2013-11-01

    In this paper, we reported a simple and efficient protocol for preparation of Cu2+-modified magnetic Fe3O4@SiO2 core/shell microspheres for immobilization of cellulase. The uniform magnetic Fe3O4@SiO2 core/shell microspheres with a thin shell of 20 nm were synthesized through a solvothermal method followed by a sol-gel process. An amino-terminated silane coupling agent of (3-aminopropyl)triethoxysilane (APTS) was then grafted on them for capturing Cu2+ ions. The reaction process is very simple, efficient, and economical. Noticeably, the content of Cu2+ ions on the magnetic core/shell microspheres can reach 4.6 Wt%, endowing them possess as high immobilization capacity as 225.5 mg/g for cellulase. And the immobilized cellulase can be retained over 90 % on the magnetic microspheres after six cycles. Meanwhile, the magnetic microspheres decorated with Cu2+ ions show a superparamagnetic character with a high magnetic saturation of 58.5 emu/g at room temperature, suggesting conveniently and rapidly recycle the enzyme from solution. This facile, recyclable, high immobilization capacity and activity strategy may find potential applications in enzyme catalytic reactions with low cost.

  15. Preparation of Fe3O4@C@PANI magnetic microspheres for the extraction and analysis of phenolic compounds in water samples by gas chromatography-mass spectrometry.

    PubMed

    Meng, Jiaoran; Shi, Chenyi; Wei, Biwen; Yu, Wenjia; Deng, Chunhui; Zhang, Xiangmin

    2011-05-20

    In this work, core-shell structure Fe(3)O(4)@C@polyaniline magnetic microspheres were synthesized using simple hydrothermal reactions. The carbon-coated magnetic microspheres (Fe(3)O(4)@C) were first synthesized by a hydrothermal reaction, and then aniline was polymerized on the magnetic core via another hydrothermal reaction. Then, the obtained Fe(3)O(4)@C@polyaniline magnetic microspheres were applied as magnetic adsorbents for the extraction of aromatic molecules due to π-π interactions between polyaniline shell and aromatic compounds. In our study, five kinds of phenols including phenol, 2,4-dichlorophenol (DCP), 2,4,5-trichlorophenol (TCP), pentachlorophenol (PCP) and bisphenol A (BPA) were selected as the model analytes to verify the extraction ability of Fe(3)O(4)@C@PANI microspheres. After derivatization, the phenols were detected using gas chromatography-mass spectrometry (GC-MS). The dominant parameters affecting enrichment efficiency were investigated and optimized. Under the optimal conditions, the proposed method was evaluated, and applied to the analysis of phenols in real water samples. The results demonstrated that our proposed method based on Fe(3)O(4)@C@polyaniline magnetic microspheres had good linearity (r(2)>0.991), and limits of quantification (2.52-29.7 ng/mL), high repeatability (RSD<13.1%) and good recovery (85.3-110.6%).

  16. Core-shell hollow microspheres of magnetic iron oxide@amorphous calcium phosphate: synthesis using adenosine 5'-triphosphate and application in pH-responsive drug delivery.

    PubMed

    Lu, Bing-Qiang; Zhu, Ying-Jie; Chen, Feng; Qi, Chao; Zhao, Xin-Yu; Zhao, Jing

    2014-10-01

    Drug nanocarriers with magnetic targeting and pH-responsive drug-release behavior are promising for applications in controlled drug delivery. Magnetic iron oxides show excellent magnetism, but their application in drug delivery is limited by low drug-loading capacity and poor control over drug release. Herein, core-shell hollow microspheres of magnetic iron oxide@amorphous calcium phosphate (MIO@ACP) were prepared and investigated as magnetic, pH-responsive drug nanocarriers. Hollow microspheres of magnetic iron oxide (HMIOs) were prepared by etching solid MIO microspheres in hydrochloric acid/ethanol solution. After loading a drug into the HMIOs, the drug-loaded HMIOs were coated with a protective layer of ACP by using adenosine 5'-triphosphate (ATP) disodium salt (Na2 ATP) as stabilizer, and drug-loaded core-shell hollow microspheres of MIO@ACP (HMIOs/drug/ACP) were obtained. The as-prepared HMIOs/drug/ACP drug-delivery system exhibits superparamagnetism and pH-responsive drug-release behavior. In a medium with pH 7.4, drug release was slow, but it was significantly accelerated at pH 4.5 due to dissolution of the ACP shell. Docetaxel-loaded core-shell hollow microspheres of MIO@ACP exhibited high anticancer activity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Chemical and bioanalytical assessments on drinking water treatments by quaternized magnetic microspheres.

    PubMed

    Shi, Peng; Ma, Rong; Zhou, Qing; Li, Aimin; Wu, Bing; Miao, Yu; Chen, Xun; Zhang, Xuxiang

    2015-03-21

    This study aimed to compare the toxicity reduction performance of conventional drinking water treatment (CT) and a treatment (NT) with quaternized magnetic microspheres (NDMP) based on chemical analyses. Fluorescence excitation-emission-matrix combined with parallel factor analysis identified four components in source water of different rivers or lake, and the abundance of each component differed greatly among the different samples. Compared with the CT, the NT evidently reduced the concentrations of dissolved organic carbon, adsorbable organic halogens (AOX), bromide and disinfection by-products. Toxicological evaluation indicated that the NT completely eliminated the cytotoxicity, and greatly reduced the genotoxicity and oxidative stress of all raw water. In contrast, the CT increased the cytotoxicity of Taihu Lake and the Zhongshan River water, genotoxicity of Taihu Lake and the Mangshe River water, as well as the levels of superoxide dismutase and malondialdehyde of the Mangshe River water. Correlation analysis indicated that the AOX of the treated samples was significantly correlated with the genotoxicity and glutathione concentration, but exhibited no correlation with either of them for all the samples. As it can effectively reduce pollutant levels and the toxicities of drinking water, NDMP might be widely used for drinking water treatment in future. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Hierarchically assembled NiCo@SiO2@Ag magnetic core-shell microspheres as highly efficient and recyclable 3D SERS substrates.

    PubMed

    Zhang, Maofeng; Zhao, Aiwu; Wang, Dapeng; Sun, Henghui

    2015-01-21

    The hierarchically nanosheet-assembled NiCo@SiO2@Ag (NSA) core-shell microspheres have been synthesized by a layer-by-layer procedure at ambient temperature. The mean particle size of NSA microspheres is about 1.7 μm, which is made up of some nanosheets with an average thickness of ∼20 nm. The outer silver shell surface structures can be controlled well by adjusting the concentration of Ag(+) ions and the reaction times. The obtained NSA 3D micro/nanostructures show a structure enhanced SERS performance, which can be attributed to the special nanoscale configuration with wedge-shaped surface architecture. We find that NSA microspheres with nanosheet-assembled shell structure exhibit the highest enhancement efficiency and high SERS sensitivity to p-ATP and MBA molecules. We show that the detection limits for both p-ATP and MBA of the optimized NSA microsphere substrates can approach 10(-7) M. And the relative standard deviation of the Raman peak maximum is ∼13%, which indicates good uniformity of the substrate. In addition, the magnetic NSA microspheres with high saturation magnetization show a quick magnetic response, good recoverability and recyclability. Therefore, such NSA microspheres may have great practical potential applications in rapid and reproducible trace detection of chemical, biological and environment pollutants with a simple portable Raman instrument.

  19. Preparation of polysulfone hollow microspheres encapsulating DNA and their functional utilization.

    PubMed

    Zhao, C; Liu, X D; Nomizu, M; Nishi, N

    2004-05-01

    Polysulfone hollow microspheres encapsulating DNA were prepared using a liquid-liquid phase separation technique. The microspheres were then used to absorb a DNA-binding intercalating material--ethidium bromide. The amount of DNA encapsulated in the microspheres depended on the concentration of the DNA solution used to prepare the microspheres, and the microsphere morphology depended on both the polymer concentration and the preparation conditions. The amount of ethidium bromide in the microspheres depended mainly on the amount of encapsulated DNA, and the microsphere morphology also affected the removal of the ethidium bromide. The new method of DNA encapsulation is proposed, and the microspheres encapsulating the DNA have the potential to be used in environmental applications.

  20. Optical Response of Magnetic-Fluorescent Microspheres Used for Force Spectroscopy in the Evanescent Field

    PubMed Central

    Bijamov, Alex; Shubitidze, Fridon; Oliver, Piercen M.; Vezenov, Dmitri V.

    2010-01-01

    Force spectroscopy based on magnetic tweezers is a powerful technique to manipulate single biomolecules and study their interactions. The resolution in a magnetic probe displacement, however, needs to be commensurate with molecular sizes. To achieve the desirable sensitivity in tracking displacements of the magnetic probe, some recent approaches have combined magnetic tweezers with total internal reflection fluorescence microscopy. In this situation, a typical force probe is a polymer microsphere containing two types of optically active components – a pure absorber (magnetic nanoparticles for providing the pulling force) and a luminophore (semiconducting nanoparticles or organic dyes for fluorescent imaging). In order to fully assess the system’s capability for tracking the position of the force probe with sub-nanometer accuracy, we developed a body-of-revolution formulation of the method of auxiliary sources (BOR-MAS) to simulate absorption, scattering, and fluorescence of microscopic spheres in an evanescent electromagnetic field. The theoretical formulation uses the axial symmetry of the system to reduce the dimensionality of the modeling problem and produces excellent agreement with the reported experimental data on forward scattering intensity. Using the BOR-MAS numerical model, we investigated the probe detection sensitivity for a high numerical aperture objective. The analysis of both backscattering and fluorescence observation modes shows that the total intensity of the bead image decays exponentially with the distance from the surface (or the length of a biomolecule). Our investigations demonstrate that the decay lengths of observable optical power are smaller than the penetration depth of the unperturbed excitation evanescent wave. In addition, our numerical modeling results illustrate that the expected sensitivity for the decay length changes with the incident angle, tracking the theoretical penetration depth for a two-media model, and is sensitive

  1. Optical response of magnetic fluorescent microspheres used for force spectroscopy in the evanescent field.

    PubMed

    Bijamov, Alex; Shubitidze, Fridon; Oliver, Piercen M; Vezenov, Dmitri V

    2010-07-20

    Force spectroscopy based on magnetic tweezers is a powerful technique for manipulating single biomolecules and studying their interactions. The resolution in magnetic probe displacement, however, needs to be commensurate with molecular sizes. To achieve the desirable sensitivity in tracking displacements of the magnetic probe, some recent approaches have combined magnetic tweezers with total internal reflection fluorescence microscopy. In this situation, a typical force probe is a polymer microsphere containing two types of optically active components: a pure absorber (magnetic nanoparticles for providing the pulling force) and a luminophore (semiconducting nanoparticles or organic dyes for fluorescent imaging). To assess the system's capability fully with regard to tracking the position of the force probe with subnanometer accuracy, we developed a body-of-revolution formulation of the method of auxiliary sources (BOR-MAS) to simulate the absorption, scattering, and fluorescence of microscopic spheres in an evanescent electromagnetic field. The theoretical formulation uses the axial symmetry of the system to reduce the dimensionality of the modeling problem and produces excellent agreement with the reported experimental data on forward scattering intensity. Using the BOR-MAS numerical model, we investigated the probe detection sensitivity for a high numerical aperture objective. The analysis of both backscattering and fluorescence observation modes shows that the total intensity of the bead image decays exponentially with the distance from the surface (or the length of a biomolecule). Our investigations demonstrate that the decay lengths of observable optical power are smaller than the penetration depth of the unperturbed excitation evanescent wave. In addition, our numerical modeling results illustrate that the expected sensitivity for the decay length changes with the angle of incidence, tracking the theoretical penetration depth for a two-media model, and is

  2. Preparation of Novel Poly(hydroxyethyl methacrylate-coglycidyl methacrylate)-Grafted Core-Shell Magnetic Chitosan Microspheres and Immobilization of Lactase

    PubMed Central

    Zhao, Wei; Yang, Rui-Jin; Qian, Ting-Ting; Hua, Xiao; Zhang, Wen-Bin; Katiyo, Wendy

    2013-01-01

    Poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted magnetic chitosan microspheres (HG-MCM) were prepared using reversed-phase suspension polymerization method. The HG-MCM presented a core-shell structure and regular spherical shape with poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) grafted onto the chitosan layer coating the Fe3O4 cores. The average diameter of the magnetic microspheres was 10.67 μm, within a narrow size distribution of 6.6–17.4 μm. The saturation magnetization and retentivity of the magnetic microspheres were 7.0033 emu/g and 0.6273 emu/g, respectively. The application of HG-MCM in immobilization of lactase showed that the immobilized enzyme presented higher storage, pH and thermal stability compared to the free enzyme. This indicates that HG-MCM have potential applications in bio-macromolecule immobilization. PMID:23743822

  3. Preparation of novel poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted core-shell magnetic chitosan microspheres and immobilization of lactase.

    PubMed

    Zhao, Wei; Yang, Rui-Jin; Qian, Ting-Ting; Hua, Xiao; Zhang, Wen-Bin; Katiyo, Wendy

    2013-06-06

    Poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted magnetic chitosan microspheres (HG-MCM) were prepared using reversed-phase suspension polymerization method. The HG-MCM presented a core-shell structure and regular spherical shape with poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) grafted onto the chitosan layer coating the Fe3O4 cores. The average diameter of the magnetic microspheres was 10.67 μm, within a narrow size distribution of 6.6-17.4 μm. The saturation magnetization and retentivity of the magnetic microspheres were 7.0033 emu/g and 0.6273 emu/g, respectively. The application of HG-MCM in immobilization of lactase showed that the immobilized enzyme presented higher storage, pH and thermal stability compared to the free enzyme. This indicates that HG-MCM have potential applications in bio-macromolecule immobilization.

  4. High quality factor silica microspheres functionalized with self-assembled nanomaterials.

    PubMed

    Kandas, Ishac; Zhang, Baigang; Daengngam, Chalongrat; Ashry, Islam; Jao, Chih-Yu; Peng, Bo; Ozdemir, Sahin K; Robinson, Hans D; Heflin, James R; Yang, Lan; Xu, Yong

    2013-09-09

    With extremely low material absorption and exceptional surface smoothness, silica-based optical resonators can achieve extremely high cavity quality (Q) factors. However, the intrinsic material limitations of silica (e.g., lack of second order nonlinearity) may limit the potential applications of silica-based high Q resonators. Here we report some results in utilizing layer-by-layer self-assembly to functionalize silica microspheres with nonlinear and plasmonic nanomaterials while maintaining Q factors as high as 10(7). We compare experimentally measured Q factors with theoretical estimates, and find good agreement.

  5. Synthesis of polystyrene microspheres and functionalization with Pd(0) nanoparticles to perform bioorthogonal organometallic chemistry in living cells.

    PubMed

    Unciti-Broceta, Asier; Johansson, Emma M V; Yusop, Rahimi M; Sánchez-Martín, Rosario M; Bradley, Mark

    2012-05-31

    We have developed miniaturized heterogeneous Pd(0)-catalysts (Pd(0)-microspheres) with the ability to enter cells, stay harmlessly within the cytosol and mediate efficient bioorthogonal organometallic chemistries (e.g., allylcarbamate cleavage and Suzuki-Miyaura cross-coupling). This approach is a major addition to the toolbox available for performing chemical reactions within cells. Here we describe a full protocol for the synthesis of the Pd(0)-microspheres from readily available starting materials (by the synthesis of size-controlled amino-functionalized polystyrene microspheres), as well as for their characterization (electron microscopy and palladium quantitation) and functional validation ('in solution' and 'in cytoplasm' conversions). From the beginning of the synthesis to functional evaluation of the catalytic device requires 5 d of work.

  6. Magnetic C-C@Fe3O4 double-shelled hollow microspheres via aerosol-based Fe3O4@C-SiO2 core-shell particles.

    PubMed

    Zhu, Yangzhi; Li, Xiangcun; He, Gaohong; Qi, Xinhong

    2015-02-18

    Magnetic C-C@Fe3O4 hollow microspheres were prepared by using aerosol-based Fe3O4@C-SiO2 core-shell particles as templates. The magnetic double-shelled microspheres efficiently worked as carriers to load Pt nanoparticles, thus making the catalyst recyclable and reusable.

  7. Localized and sustained delivery of erythropoietin from PLGA microspheres promotes functional recovery and nerve regeneration in peripheral nerve injury.

    PubMed

    Zhang, Wei; Gao, Yuan; Zhou, Yan; Liu, Jianheng; Zhang, Licheng; Long, Anhua; Zhang, Lihai; Tang, Peifu

    2015-01-01

    Erythropoietin (EPO) has been demonstrated to exert neuroprotective effects on peripheral nerve injury recovery. Though daily intraperitoneal injection of EPO during a long period of time was effective, it was a tedious procedure. In addition, only limited amount of EPO could reach the injury sites by general administration, and free EPO is easily degraded in vivo. In this study, we encapsulated EPO in poly(lactide-co-glycolide) (PLGA) microspheres. Both in vitro and in vivo release assays showed that the EPO-PLGA microspheres allowed sustained release of EPO within a period of two weeks. After administration of such EPO-PLGA microspheres, the peripheral nerve injured rats had significantly better recovery compared with those which received daily intraperitoneal injection of EPO, empty PLGA microspheres, or saline treatments. This was supported by the functional, electrophysiological, and histological evaluations of the recovery done at week 8 postoperatively. We conclude that sustained delivery of EPO could be achieved by using EPO-PLGA microspheres, and such delivery method could further enhance the recovery function of EPO in nerve injury recovery.

  8. Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres: Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres

    SciTech Connect

    Khromova, Irina; Kužel, Petr; Brener, Igal; Reno, John L.; Chung Seu, U-Chan; Elissalde, Catherine; Maglione, Mario; Mounaix, Patrick; Mitrofanov, Oleg

    2016-06-27

    Monocrystalline titanium dioxide (TiO2) micro-spheres support two orthogonal magnetic dipole modes at terahertz (THz) frequencies due to strong dielectric anisotropy. For the first time, we experimentally detected the splitting of the first Mie mode in spheres of radii inline imagem through near-field time-domain THz spectroscopy. By fitting the Fano lineshape model to the experimentally obtained spectra of the electric field detected by the sub-wavelength aperture probe, we found that the magnetic dipole resonances in TiO2 spheres have narrow linewidths of only tens of gigahertz. Lastly, anisotropic TiO2 micro-resonators can be used to enhance the interplay of magnetic and electric dipole resonances in the emerging THz all-dielectric metamaterial technology.

  9. Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres: Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres

    SciTech Connect

    Khromova, Irina; Kužel, Petr; Brener, Igal; Reno, John L.; Chung Seu, U-Chan; Elissalde, Catherine; Maglione, Mario; Mounaix, Patrick; Mitrofanov, Oleg

    2016-06-27

    Monocrystalline titanium dioxide (TiO2) micro-spheres support two orthogonal magnetic dipole modes at terahertz (THz) frequencies due to strong dielectric anisotropy. For the first time, we experimentally detected the splitting of the first Mie mode in spheres of radii inline imagem through near-field time-domain THz spectroscopy. By fitting the Fano lineshape model to the experimentally obtained spectra of the electric field detected by the sub-wavelength aperture probe, we found that the magnetic dipole resonances in TiO2 spheres have narrow linewidths of only tens of gigahertz. Lastly, anisotropic TiO2 micro-resonators can be used to enhance the interplay of magnetic and electric dipole resonances in the emerging THz all-dielectric metamaterial technology.

  10. Solid phase extraction using magnetic core mesoporous shell microspheres with C18-modified interior pore-walls for residue analysis of cephalosporins in milk by LC-MS/MS.

    PubMed

    Liu, Xiaodan; Yu, Yingjia; Zhao, Meiyan; Zhang, Haiying; Li, Yan; Duan, Gengli

    2014-05-01

    A fast and effective extraction method has been developed for measuring the residue of cephalosporins (cefalexin, cefazolin, cefoperazone) in milk by using magnetic core-mesoporous shell microspheres with C18-functionalized interior pore-walls (C18-Fe3O4@mSiO2) as adsorbent. With no need for any protein precipitation procedure, the cephalosporins were directly adsorbed onto the C18-Fe3O4@mSiO2 microspheres through hydrophobic interaction with C18-groups (Octadecyl functional groups) functionalized in the interior walls of mesopore channels while the abundant proteins in milk sample were excluded out of the channel due to the size exclusion effect. Thereafter, the cephalosporins-absorbed C18-Fe3O4@mSiO2 microspheres were rapidly isolated by placing a magnet, and followed by liquid chromatography-tandem mass spectrometry analysis after eluted by methanol. Various parameters which could affect the extraction performance were optimised. The newly developed extraction method was successfully applied in determination of cephalosporin residues in milk samples, offering a valuable alternative to simplify and speed up the sample preparation step.

  11. High efficiency and quantitatively reproducible protein digestion by trypsin-immobilized magnetic microspheres

    PubMed Central

    Sun, Liangliang; Li, Yihan; Yang, Ping; Zhu, Guijie; Dovichi, Norman J.

    2011-01-01

    Aldehyde- and NHS-activated magnetic microspheres were used to immobilize trypsin (CHO-trypsin and NHS-trypsin), and their performance for protein digestion was evaluated by reversed phase liquid chromatography-electrospray ionization-tandem mass spectrometry using an LTQ Orbitrap Velos instrument. NHS-trypsin provided greater sequence coverage and identified more peptides for the digestion of bovine serum albumin. A one-minute digestion at room temperature using the immobilized trypsin also identified more peptides (96 ± 6 vs. 48 ± 1) and produced higher sequence coverage (90 ± 2% vs. 75 ± 2%) than traditional free trypsin digestion for 12 hours at 37 °C. Analysis of 15 nM (0.001 mg/mL) BSA digested by NHS-trypsin in 1 min. at room temperature consistently yielded one detected peptide; 150 nM BSA generated 22 peptides. Peptide intensity and protein spectral count were used to evaluate the run-to-run digestion reproducibility of NHS-trypsin with a three-protein-mixture. Three high intensity peptides for each protein generated intensity ratios from 0.70 to 1.09 and spectral count ratios from 0.78 to 1.18. Finally, RAW 264.7 cell lysates were digested by NHS-trypsin for 10 min. and 30 min. at room temperature; 604 and 697 protein groups, respectively, were identified by RPLC-ESI-MS/MS, with a peptide false discovery rate of less than 1%. Digestion by solution phase trypsin for 12 hours at 37 °C resulted in identification of 878 protein groups. PMID:22176736

  12. Simultaneous removal of acid green 25 and mercury ions from aqueous solutions using glutamine modified chitosan magnetic composite microspheres.

    PubMed

    Tao, Xue; Li, Kun; Yan, Han; Yang, Hu; Li, Aimin

    2016-02-01

    In this current work, the magnetic composite microsphere containing glutamine modified chitosan and silica coated Fe3O4 nanoparticles (CS-Gln-MCM) has been successfully prepared and extensively characterized, which is a kind of biodegradable materials. CS-Gln-MCM shows enhanced removal efficiency for both acid green 25 (AG25), an amphoteric dye, and mercury ions (Hg(2+)) from water in the respective while measured pH range compared with chitosan magnetic composite microsphere (CS-MCM) without modification. It is due to the fact that the grafted amino acid provides a variety of additional adsorption active sites and diverse adsorption mechanisms are involved. In AG25 and Hg(2+) aqueous mixture, the modified adsorbents bear preferential adsorption for AG25 over Hg(2+) in strong acidic solutions ascribed to multiple interactions between AG25 and CS-Gln-MCM, such as hydrogen bonding and electrostatic interactions. While, in weak acidic conditions, an efficient simultaneous removal is observed for different adsorption effects involved in aforementioned two pollutants. Besides, CS-Gln-MCM illuminates not only short equilibrium time for adsorption of each pollutant less than 20.0 min but also rapid magnetic separation from water and efficient regeneration after saturated adsorption. Therefore, CS-Gln-MCM bears great application potentials in water treatment.

  13. Preparation of magnetic Fe3O4/TiO2/Ag composite microspheres with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Wu, Zheng; Chen, Liangwei; Zhang, Lianjie; Li, Xuelian; Xu, Haifeng; Wang, Hongyan; Zhu, Guang

    2016-02-01

    The novel three-component Fe3O4/TiO2/Ag composite mircospheres were prepared via a facile chemical deposition route. The Fe3O4/TiO2 mircospheres were first prepared by the solvothermal method, and then Ag nanoparticles were anchored onto the out-layer of TiO2 by the tyrosine-reduced method. The as-prepared magnetic Fe3O4/TiO2/Ag composite mircospheres were applied as photocatalysis for the photocatalytic degradation of methylene blue. The results indicate that the photocatalytic activity of Fe3O4/TiO2/Ag composite microspheres is superior to that of Fe3O4/TiO2 due to the dual effects of the enhanced light absorption and reduction of photoelectron-hole pair recombination in TiO2 with the introduction of Ag NPs. Moreover, these magnetic Fe3O4/TiO2/Ag composite microspheres can be completely removed from the dispersion with the help of magnetic separation and reused with little or no loss of catalytic activity.

  14. An effective and recyclable adsorbent for the removal of heavy metal ions from aqueous system: Magnetic chitosan/cellulose microspheres.

    PubMed

    Luo, Xiaogang; Zeng, Jian; Liu, Shilin; Zhang, Lina

    2015-10-01

    Development of highly cost-effective, highly operation-convenient and highly efficient natural polymer-based adsorbents for their biodegradability and biocompatibility, and supply of safe drinking water are the most threatening problems in water treatment field. To tackle the challenges, a new kind of efficient recyclable magnetic chitosan/cellulose hybrid microspheres was prepared by sol-gel method. By embedding magnetic γ-Fe2O3 nanoparticles in chitosan/cellulose matrix drops in NaOH/urea aqueous solution, it combined renewability and biocompatibility of chitosan and cellulose as well as magnetic properties of γ-Fe2O3 to create a hybrid system in heavy metal ions removal. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Functionalized antibiofilm thin coatings based on PLA-PVA microspheres loaded with usnic acid natural compounds fabricated by MAPLE

    NASA Astrophysics Data System (ADS)

    Grumezescu, Valentina; Socol, Gabriel; Grumezescu, Alexandru Mihai; Holban, Alina Maria; Ficai, Anton; Truşcǎ, Roxana; Bleotu, Coralia; Balaure, Paul Cǎtǎlin; Cristescu, Rodica; Chifiriuc, Mariana Carmen

    2014-05-01

    We report the fabrication of thin coatings of PLA-PVA microspheres loaded with usnic acid by matrix assisted pulsed laser evaporation (MAPLE) onto Ti substrate. The obtained coatings have been physico-chemically characterized by scanning electron microscopy (SEM) and infrared microscopy (IRM). In vitro biological assays have been performed in order to evaluate the influence of fabricated microsphere thin coatings on the Staphylococcus aureus biofilm development as well as their biocompatibility. SEM micrographs have revealed a uniform morphology of thin coatings, while IRM investigations have proved both the homogeneity and functional groups integrity of prepared thin coatings. The obtained microsphere-based thin coatings have proved to be efficient vehicles for usnic acid natural compound with antibiofilm activity, as demonstrated by the inhibitory activity on S. aureus mature biofilm development, opening new perspectives for the prevention and therapy associated to biofilm related infections.

  16. Preparation of monodisperse PEG hydrogel composite microspheres via microfluidic chip with rounded channels

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Cong, Hailin; Liu, Xuesong; Ren, Yumin; Wang, Jilei; Zhang, Lixin; Tang, Jianguo; Ma, Yurong; Akasaka, Takeshi

    2013-09-01

    An effective microfluidic method to fabricate monodisperse polyethylene glycol (PEG) hydrogel composite microspheres with tunable dimensions and properties is reported in this paper. A T-junction microfluidic chip equipped with rounded channels and online photopolymerization system is applied for the microsphere microfabrication. The shape and size of the microspheres are well controlled by the rounded channels and PEG prepolymer/silicon oil flow rate ratios. The obtained PEG/aspirin composite microspheres exhibit a sustained release of aspirin for a wide time range; the obtained PEG/Fe3O4 nanocomposite microspheres exhibit excellent magnetic properties; and the obtained binary PEG/dye composite microspheres show the ability to synchronously load two functional components in the same peanut-shaped or Janus hydrogel particles.

  17. Amine-functionalized monodispersed porous silica microspheres with enhanced CO2 adsorption performance and good cyclic stability.

    PubMed

    Le, Yao; Guo, Daipeng; Cheng, Bei; Yu, Jiaguo

    2013-10-15

    Carbon dioxide capture using solid adsorbent has caused more and more attention in the world. Herein, amine-functionalized monodispersed porous silica microspheres (MPSM) were prepared by the hydrolysis and condensation of tetraethoxysilane (TEOS) in a water-ethanol-dodecylamine mixed solution, then calcined at 600°C, and finally functionalized with tetraethylenepentamine (TEA). The CO2 adsorption performance of the prepared samples was measured using a Chemisorb 2720 pulse chemisorption system (Micromeritics, USA). The results showed that the specific surface area and pore volume of the 600°C-calcined SiO2 microspheres reached 921m(2)/g and 0.48cm(3)/g, respectively. All the TEA-functionalized samples exhibited good CO2 adsorption performance, which were related to the amount of loaded TEA, adsorption temperatures, and the specific surface areas of the prepared samples. An optimal TEA loading amount (34wt%) and adsorption temperature (75°C) were determined. The maximum CO2 adsorption amount (4.27mmolg(-1) adsorbent) was achieved on the 600°C-calcined SiO2 microsphere sample with TEA loading of 34wt%. Repeated adsorption/desorption cycle experiments revealed that the TEA-functionalized SiO2 microspheres were good CO2 adsorbents exhibiting excellent cyclic stability.

  18. Separation of PCR-ready DNA from dairy products using magnetic hydrophilic microspheres and poly(ethylene glycol)-NaCl water solutions

    NASA Astrophysics Data System (ADS)

    Rittich, Bohuslav; Španová, Alena; Šálek, Petr; Němcová, Petra; Trachtová, Štěpánka; Horák, Daniel

    2009-05-01

    Carboxyl group-containing magnetic nonporous poly(2-hydroxyethyl methacrylate- co-glycidyl methacrylate) (P(HEMA- co-GMA)) and magnetic glass microspheres were used for the isolation of bacterial DNA. P(HEMA- co-GMA) microspheres were prepared by the dispersion polymerization in toluene/2-methylpropan-1-ol mixture in the presence of magnetite nanoparticles obtained by coprecipitation of Fe(II) and Fe(III) salts with ammonium hydroxide. Carboxyl groups were then introduced by oxidation of the microspheres with potassium permanganate. The most extensive DNA recovery was achieved at PEG 6000 concentrations of 12% or 16% and 2 M NaCl. The method proposed was used for bacterial DNA isolation from different dairy products containing Bifidobacterium and Lactobacillus cells. The presence of target DNA and the quality of isolated DNA were checked by polymerase chain reaction (PCR) amplification with specific primers.

  19. Functional magnetic resonance imaging.

    PubMed

    Buchbinder, Bradley R

    2016-01-01

    Functional magnetic resonance imaging (fMRI) maps the spatiotemporal distribution of neural activity in the brain under varying cognitive conditions. Since its inception in 1991, blood oxygen level-dependent (BOLD) fMRI has rapidly become a vital methodology in basic and applied neuroscience research. In the clinical realm, it has become an established tool for presurgical functional brain mapping. This chapter has three principal aims. First, we review key physiologic, biophysical, and methodologic principles that underlie BOLD fMRI, regardless of its particular area of application. These principles inform a nuanced interpretation of the BOLD fMRI signal, along with its neurophysiologic significance and pitfalls. Second, we illustrate the clinical application of task-based fMRI to presurgical motor, language, and memory mapping in patients with lesions near eloquent brain areas. Integration of BOLD fMRI and diffusion tensor white-matter tractography provides a road map for presurgical planning and intraoperative navigation that helps to maximize the extent of lesion resection while minimizing the risk of postoperative neurologic deficits. Finally, we highlight several basic principles of resting-state fMRI and its emerging translational clinical applications. Resting-state fMRI represents an important paradigm shift, focusing attention on functional connectivity within intrinsic cognitive networks.

  20. Magnetic metal-organic framework MIL-100(Fe) microspheres for the magnetic solid-phase extraction of trace polycyclic aromatic hydrocarbons from water samples.

    PubMed

    Du, Fuyou; Qin, Qun; Deng, Jianchao; Ruan, Guihua; Yang, Xianqing; Li, Laihao; Li, Jianping

    2016-06-01

    In this work, a magnetic metal-organic framework designated as MIL-100(Fe) was prepared and applied as a magnetic solid-phase extraction sorbent for the determination of trace polycyclic aromatic hydrocarbons in environmental water samples by coupling with high-performance liquid chromatography and fluorescence detection. The magnetic microspheres exhibited large surface areas and high extraction ability, making them excellent candidates as sorbents for enrichment of trace polycyclic aromatic hydrocarbons. Under the optimized experimental conditions, good sensitivity levels were achieved with low detection limits ranging from 32 to 2110 pg/mL and good linearities with correlation coefficients higher than 0.9990 for the investigated 13 polycyclic aromatic hydrocarbons. The proposed method has been validated in the analysis of real water samples with mean recoveries in the range of 81.4-126.9% at four spiked levels and the relative standard deviations in the range of 1.3-17.0%. The magnetic MIL-100(Fe) microspheres were stable enough for 150 extractions without a significant loss of extraction performance.

  1. Polyaniline-coated chitosan-functionalized magnetic nanoparticles: Preparation for the extraction and analysis of endocrine-disrupting phenols in environmental water and juice samples.

    PubMed

    Jiang, Xilan; Cheng, Jing; Zhou, Hongbin; Li, Feng; Wu, Wenlin; Ding, Kerong

    2015-08-15

    In the present study, chitosan (CHI) functionalized Fe3O4 magnetic microspheres coated with polyaniline (PANI) were synthesized for the first time. The chitosan-functionalized magnetic microspheres (Fe3O4@CHI) were synthesized by a co-precipitation method, and then aniline was polymerized on the magnetic core. The obtained Fe3O4@CHI@PANI microspheres were spherical core-shell structure with uniform size at about 100nm with 20-30nm diameter core. The microspheres had a high saturation magnetization of 32emu g(-)(1), which was sufficient for magnetic separation. The obtained Fe3O4@CHI@PANI magnetic microspheres were applied as magnetic adsorbents for the extraction of aromatic compounds via π-π interaction between polyaniline shell and aromatic compounds. Three endocrine-disrupting phenols, including bisphenol A (BPA), 2, 4-dichlorophenol (2, 4-DCP), and triclosan (TCS) were selected as the model analytes to verify the extraction ability of Fe3O4@CHI@PANI. The hydrophilic chitosan-functionalized Fe3O4 core (Fe3O4@CHI) improved the dispersibility of Fe3O4@CHI@PANI microspheres, and then improve its extraction efficiency. The dominant parameters affecting enrichment efficiency were investigated and optimized. Under optimal condition, the proposed method was evaluated, and applied to the analysis of phenols in real water and juice samples. The results demonstrated the method based on Fe3O4@CHI@PANI magnetic microspheres had good linearity (R(2)>0.996), and limits of detection (0.10-0.13ng mL(-1)), high repeatability (RSD<6.6%) and good recovery (85.0-106.7%). Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Novel ferroferric oxide/polystyrene/silver core-shell magnetic nanocomposite microspheres as regenerable substrates for surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Bai, Chong; Zhao, Dan; Liu, Wei-Liang; Ren, Man-Man; Liu, Qin-Ze; Yang, Zhi-Zhou; Wang, Xin-Qiang; Duan, Xiu-Lan

    2016-02-01

    A novel Ag-coated Fe3O4@Polystyrene core-shell microsphere has been designed via fabrication of Fe3O4@Polystyrene core-shell magnetic microsphere through a seed emulsion polymerization, followed by deposition of Ag nanoparticles using in-situ reduction method. Such magnetic microspheres can be utilized as sensitive surface-enhanced Raman scattering (SERS) substrates, using Rhodamine 6G (R6G) as a probe molecule, with both stable and reproducible performances. The SERS detection limit of R6G decreased to 1 × 10-10 M and the enhancement factor of this substrate on the order of 106 was obtained. In addition, owing to possessing excellent magnetic properties, the resultant microspheres could be separated rapidly by an external magnetic field and utilized repeatedly for three times at least. Therefore, the unique renewable property suggests a new route to eliminate the single-use problem of traditional SERS substrates and will be promising for the practical application.

  3. Fe3O4/PANI/P(MAA-co-NVP) multilayer composite microspheres with electric and magnetic features: assembly and characterization.

    PubMed

    Luo, Yan-Ling; Fan, Li-Hua; Gao, Gai-Ling; Chen, Ya-Shao; Shao, Xiao-Hua

    2009-11-01

    A core-shell multilayered composite microsphere with electric and magnetic features was designed and prepared on the basis of mutilayered fabrication. This kind of microspheres was obtained by introducing a rod-like conductive polyanilline (PANI) or its derivatives onto the surface of magnetic Fe3O4 nanoparticles with 4,4'-diphenylmethane diisocyanate as a anchor molecule. Subsequently, the Fe3O4/PANI or Fe3O4/aniline oligomers microspheres, as a secondary core, were covered with a cross-linked shell layer which was constructed by a dispersion polymerization process of methacrylic acid and vinyl pyrrolidone. The structure and morphologies were characterized by using a FTIR, XRD, UV-vis, SEM, TEM and TGA. The average diameter of Fe3O4 nanoparticles prepared is about 10.7 nm, and the PANI nanobars hold the size in the range of about 20.4-25.6 nm. The PANI nanobars are covalently assembled on the surface of Fe3O4 nanoparticles mainly in a mode of extended or horizontal arrangements through XRD and TEM results. The electromagnetic properties were examined based on different polymerization degrees and component ratios of PANI or its derivatives, showing characteristics of soft magnetic materials and controllable conductivity. The multilayer microspheres can be readily used to perform separation and magnetism guide, even electric and pH-modulated drug release in the light of swelling determination and a laser diffraction particle size analyzer, and are potentially of interest for drug targeting purpose.

  4. Efficient synthesis of narrowly dispersed hydrophilic and magnetic molecularly imprinted polymer microspheres with excellent molecular recognition ability in a real biological sample.

    PubMed

    Zhao, Man; Zhang, Cong; Zhang, Ying; Guo, Xianzhi; Yan, Husheng; Zhang, Huiqi

    2014-02-28

    A facile and highly efficient approach to obtain narrowly dispersed hydrophilic and magnetic molecularly imprinted polymer microspheres with molecular recognition ability in a real biological sample as good as what they show in the organic solvent-based media is described for the first time.

  5. High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water.

    PubMed

    Wei, Yan; Yang, Ran; Zhang, Yong-Xing; Wang, Lun; Liu, Jin-Huai; Huang, Xing-Jiu

    2011-10-21

    γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.

  6. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolysis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  7. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolyis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  8. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolyis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  9. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolysis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  10. Synthesis of electromagnetic functionalized Fe3O4 microspheres/polyaniline composites by two-step oxidative polymerization.

    PubMed

    Cui, Chenkui; Du, Yunchen; Li, Tianhao; Zheng, Xiaoying; Wang, Xiaohong; Han, Xijiang; Xu, Ping

    2012-08-09

    Composites consisting of Fe(3)O(4) microspheres (FMS) and polyaniline (PANI), FMS/PANI, have been successfully prepared through a two-step oxidative polymerization of aniline monomers in the presence of Fe(3)O(4) microspheres. In our two-step polymerization technique, Fe(3+) and ammonium persulfate (APS) are used as the oxidants in each step. It is discovered that the two-step oxidative process plays a dominant role in the morphology of these composites: aniline oligomers oxidized by Fe(3+) are mainly produced in the first stage, and "egg-like" PANI aggregates are obtained in the second stage. It can be found that embedding Fe(3)O(4) microspheres in the polymer matrixes will not only modulate the complex permittivity but also produce magnetic resonance and loss in the composites. Therefore, the characteristic impedance and reflection loss of these composites are greatly improved. Especially, the composite with equal amount of FMS and PANI, FMS/PANI(50), displays very strong reflection loss over a wide frequency range that can be manipulated by the absorber thickness. More importantly, the composites prepared from the two-step chemical oxidative polymerization using hierarchical magnetic materials have better microwave absorption and environmental stability as compared with those composites from Fe(3)O(4) nanoparticles, one-step oxidative polymerization, and physical mixture. We believe the two-step oxidative polymerization technique can be a novel route for the design and preparation of lightweight and highly effective microwave absorbers in the future.

  11. Fe(3)O(4)@MOF core-shell magnetic microspheres for magnetic solid-phase extraction of polychlorinated biphenyls from environmental water samples.

    PubMed

    Chen, Xiangfeng; Ding, Ning; Zang, Hao; Yeung, Hoisze; Zhao, Ru-Song; Cheng, Chuange; Liu, Jianhua; Chan, T-W Dominic

    2013-08-23

    Fe3O4@MIL-100 core-shell magnetic microspheres were, for the first time, used as the sorbent for the magnetic solid-phase extraction (MSPE) of polychlorinated biphenyls at trace levels in environmental water samples. GC coupled with tandem MS was used for sample quantification and detection. The Box-Behnken design was used to determine the optimum extraction parameters influencing extraction efficiency through response surface methodology. Under the optimized conditions, the developed method showed good linearity within the range of 5-4000ngL(-1), low limits of detection (1.07-1.57ngL(-1); signal-to-noise ratio=3:1), and good extraction repeatability (relative standard deviation<12%; n=5). Environmental samples collected from the Yellow River, local lake, wastewater, and snow water were processed using the developed method. The results demonstrated that the Fe3O4@MOF core-shell magnetic microspheres are promising sorbents in the MSPE of aromatic pollutants from environmental water samples.

  12. Fabrication and caffeine release from Fe3O4/P(MAA-co-NVP) magnetic microspheres with controllable core-shell architecture.

    PubMed

    Di, Hong-Wei; Luo, Yan-Ling; Xu, Feng; Chen, Yao-Shao; Nan, Yun-Fei

    2011-01-01

    A novel route was proposed to design and construct a magnetic composite microsphere consisting of Fe(3)O(4) nanoparticles chemically-covalently encapsulated with pH-smart poly(methacrylic acid-co-N-vinyl pyrrolidone) (P(MAA-co-NVP)) cross-linked co-polymers by a surface-initiated radical dispersion polymerization route. The multistep surface treatment was employed to improve the dispersity and surface-chemical reactivity of Fe(3)O(4) nanoparticles, involving introduction of active -NH(2) groups, coupling of 1,1-methylene bis-(4-isocyanato-cyclohexane) and immobilization of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl) propionamide]. The structure and morphological characterization was carried out by FT-IR, TEM, SEM and XRD. The chemically covalent interactions were investigated by FT-IR, TEM, TGA and DSC. The neat Fe(3)O(4) nanoparticles took on an aggregated spherical shape with an average diameter of about 12 nm, while Fe(3)O(4)/P(MAA-co-NVP) magnetic microspheres assumed controllable and monodispersed spheres with a mean dimension of ca. 0.8 μm. The microspheres exhibited superparamagnetic properties. The in vitro caffeine release behavior under varying pH environment was investigated to evaluate the potential of Fe(3)O(4)/P(MAA-co-NVP) magnetic microspheres as a magnetic drug targeting carrier. The results indicated that the microspheres have a faster drug-release rate at pH 7.4 than at pH 1.4, corresponding to their pH swelling. The kinetic modeling demonstrated that the drug release is controlled by a balance between co-polymer chain relaxation and Fickian diffusion process, and the proposed carrier is suitable for a magnetic targeting drug-delivery system.

  13. Multi-walled carbon nanotube modified dummy-template magnetic molecularly imprinted microspheres as solid-phase extraction material for the determination of polychlorinated biphenyls in fish.

    PubMed

    Du, Xiaowen; Lin, Saichai; Gan, Ning; Chen, Xidong; Cao, Yuting; Li, Tianhua; Zhan, Pan

    2014-07-01

    Novel multi-walled carbon nanotube modified dummy-template molecularly imprinted microspheres (MWCNTs@DMMIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs). MWCNTs@DMMIPs were prepared by a surface molecular imprinting technique. Core-shell Fe3 O4 @SiO2 nanoparticles were employed as magnetic support. 3,4-Dichlorobenzene acetic acid was used as a dummy template instead of PCBs, methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate was used as the cross-linker. The resulting absorbent was characterized by various methods. The adsorbent was employed for extracting PCBs and exhibited good selectivity and high adsorption efficiency. Furthermore, it was reusable and capable of magnetic separation. Adsorption kinetics fit well with a pseudo-second-order kinetic equation and also exhibited a three-stage intra-particle diffusion model. The Freundlich model was used to describe the adsorption isotherms. The materials were successfully applied to the magnetic dispersive solid-phase extraction of six kinds of PCBs followed by gas chromatography with mass spectrometry determination in fish samples, the limit of detection of six kinds of PCBs were 0.0028-0.0068 μg/L and spiked recoveries ranged between 73.41 and 114.21%. The prepared adsorbent was expected to be a new material for the removal and recovery of PCBs from contaminated foods.

  14. Folate-bearing doxorubicin-loaded magnetic poly(N-isopropylacrylamide) microspheres as a new strategy for cancer therapy.

    PubMed

    Sun, Yong; Chen, Libo; Yu, Jerry; Zhi, Xiuling; Tang, Shaoxian; Zhou, Ping; Wang, Changchun

    2009-08-01

    Doxorubicin is a classic anticancer agent. Recently, numerous strategies have been used to enhance efficacy of drug delivery for cancer treatment. For example, by modifying poly(N-isopropylacrylamide) microspheres, a nanocarrier, makes it more effective. Conjugation with folic acid increases specific targeted drug delivery towards folate receptor-bearing cancer cells to improve anticancer effectiveness by increasing the tissue's local concentration of drugs. In the current studies, we synthesized folate-bearing, doxorubicin-loaded, magnetic, poly(N-isopropylacrylamide) microspheres (FDMPM) to treat breast cancer cells (human SKBR-3). We found efficiency of drug encapsulation very high (95%) at pH above 7.4. Reverse transcription-PCR showed that cancer cells highly expressed folate receptors. Confocal laser scanning microscopy and flow cytometry revealed internalization of the carrier by SKBR-3 in treatments with FDMPM, which was not the case with any other combination for drug delivery (MPM, FMPM, and DMPM). Similarly, SKBR-3 cell growth was inhibited more (assessed by methylthiazolyldiphenyl-tetrazolium bromide and trypan blue exclusion assays) when treated with FDMPM than with any other combinations. Current results confirm our predication and demonstrate that FDMPM has potential as a new targeting strategy in cancer therapy.

  15. Preparation of photonic-magnetic responsive molecularly imprinted microspheres and their application to fast and selective extraction of 17β-estradiol.

    PubMed

    Peng, Hailong; Luo, Mei; Xiong, Hua; Yu, Ningxiang; Ning, Fangjian; Fan, Jieping; Zeng, Zheling; Li, Jinhua; Chen, Lingxin

    2016-04-15

    Photonic-magnetic responsive molecularly imprinted microspheres (PM-MIMs) were prepared by seed polymerization, through suitable functionalization of magnetic nanoparticles for further coating with photoresponsive functional monomer and imprinted layers, and then were successfully applied to the fast and selective extraction of 17β-estradiol (17β-E2) from real samples. The PM-MIMs possessed a sandwich micro-spherical structure containing Fe3O4 core, SiO2 middle layer, and MIPs shell with thickness of 25 nm. The PM-MIMs displayed excellent photoresponsive properties and could be rapidly separated from solutions under an external magnet. The PM-MIMs had specific affinity towards 17β-E2 with high adsorption capacity (Qmax=0.84 mg g(-1)) and fast binding kinetics (Kd=26.08 mg L(-1)). The PM-MIMs proved to be an ideal photoswitch with the ability of reversible uptake and release of 17β-E2 upon alternate 365 and 440 nm irradiation: 45.0% of 17β-E2 released from the PM-MIMs upon 365 nm irradiation, and 94.0% of the released 17β-E2 was rebound to the PM-MIMs at 440 nm. Accordingly, the PM-MIMs were applied for fast separation and extraction of 17β-E2 followed by HPLC-UV determination, presenting the low limit of detection (LOD, S/N=3) and quantification (LOQ, S/N=10) of 0.18 and 0.62 μmol L(-1), respectively. The high recoveries for spiked milk powder and drinking water samples were in the range of 97.5-113.0% with relative standard deviations less than 4.4%. This study reasonably combined photonic response, magnetic separation and surface imprinting, which endowed the PM-MIMs with significant advantages of high adsorption capacity and fast binding kinetics, convenient separation and recycled use, and simple rapid eco-benign adsorption/elution processes for template molecules. Thus, the PM-MIMs based method may be a simple, rapid, convenient, cost-effective and environmentally-friendly way for simultaneous separation, enrichment and detection of trace 17β-E2 in

  16. Hybrid microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1985-01-01

    Substrates, particularly inert synthetic organic resin beads (10) or sheet (12) such as polystyrene are coated with a covalently bound layer (24) of polyacrolein by irradiation a solution (14) of acrolein or other aldehyde with high intensity radiation. Individual microspheres (22) are formed which attach to the surface to form the aldehyde containing layer (24). The aldehyde groups can be converted to other functional groups by reaction with materials such as hydroxylamine. Adducts of proteins such as antibodies or enzymes can be formed by direct reaction with the surface aldehyde groups.

  17. Catalytic properties of carboxylic acid functionalized-polymer microsphere-stabilized gold metallic colloids.

    PubMed

    Liu, Wei; Yang, Xinlin; Huang, Wenqiang

    2006-12-01

    Polymer-microsphere-stabilized gold metallic colloids have been prepared by a novel strategy of simple and convenient reduction of the metallic salt through the stabilization of the active carboxylic acid group on the gel and surface layer of the microsphere. The nature of the interaction between the carboxylic acid and Au nanoparticles was studied in detail by XPS. Preliminary results indicate that polymer-microsphere-stabilized gold colloids are active catalysts for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride as reductant. The catalytic properties of the stabilized catalyst for recycling were also investigated.

  18. Synthesis of magnetic and lightweight hollow microspheres/polyaniline/Fe 3 O 4 composite in one-step method

    NASA Astrophysics Data System (ADS)

    Sun, Li; Li, Qin; Wang, Wei; Pang, Jianfeng; Zhai, Jianping

    2011-09-01

    After hollow microspheres (HM) were surface modified, a layer of electromagnetic polyaniline/Fe3O4 composite (PAN/Fe3O4) was successfully grafted onto the surface of the self-assembled monolayer coated HM, resulting in HM/PAN/Fe3O4 composites. In this approach, γ-aminopropyltriethoxy silane was adopted to form a well-coating monolayer with amino groups for the graft polymerization of aniline, which played an important role in fabricating the core-shell structure. FeCl3 was used as the oxidant not only for aniline to form PAN, but also for FeCl2 to prepare the magnets. The structure, morphologies, and magnetic properties of the as-prepared samples were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. The results indicated that the HM/PAN/Fe3O4 composites possess low density (ρ < 1.0 g/cm3), controllable morphology, and good magnetic properties at room temperature (saturation magnetization Ms = 8.32 emu g-1 and coercive force Hc ≈ 0).

  19. Preparation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol microspheres for highly efficient sorption of uranium(VI).

    PubMed

    Tan, Lichao; Zhang, Xiaofei; Liu, Qi; Wang, Jun; Sun, Yanbo; Jing, Xiaoyan; Liu, Jingyuan; Song, Dalei; Liu, Lianhe

    2015-04-21

    We report a facile approach for the formation of magnetic core-shell iron oxide@silica@nickel-ethylene glycol (Fe3O4@SiO2@Ni-L) microspheres. The structure and morphology of Fe3O4@SiO2@Ni-L are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption isotherm. The composite possesses a high specific surface area of 382 m(2) g(-1). The obtained core/shell structure is composed of a superparamagnetic core with a strong response to external fields, which are recovered readily from aqueous solutions by magnetic separation. When used as the adsorbent for uranium(vi) in water, the as-prepared Fe3O4@SiO2@Ni-L multi-structural microspheres exhibit a high adsorption capacity, which is mainly attributed to the large specific surface area and typical mesoporous characteristics of Fe3O4@SiO2@Ni-L microspheres. This work provides a promising approach for the design and synthesis of multifunctional microspheres, which can be used for water treatment, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors.

  20. Fluorocarbon-bonded magnetic mesoporous microspheres for the analysis of perfluorinated compounds in human serum by high-performance liquid chromatography coupled to tandem mass spectrometry.

    PubMed

    Liu, Xiaodan; Yu, Yingjia; Li, Yan; Zhang, Haiying; Ling, Jin; Sun, Xueni; Feng, Jianan; Duan, Gengli

    2014-09-24

    We report herein an extraction method for the analysis of perfluorinated compounds in human serum based on magnetic core-mesoporous shell microspheres with decyl-perfluorinated interior pore-walls (Fe3O4@mSiO2-F17). Thanks to the unique properties of the Fe3O4@mSiO2-F17 microspheres, macromolecules like proteins could be easily excluded from the mesoporous channels due to size exclusion effect, and perfluorinated compounds (PFCs) in protein-rich biosamples such as serum could thus be directly extracted with the fluorocarbon modified on the channel wall without any other pretreatment procedure. The PFCs adsorbed Fe3O4@mSiO2-F17 microspheres could then be simply and rapidly isolated by using a magnet, followed by being identified and quantified by LC-MS/MS (high-performance liquid chromatography coupled to tandem mass spectrometry). Five perfluorinatedcarboxylic acids (C6, C8-C11) and perfluorooctane sulfonate (PFOS) were selected as model analytes. In order to achieve the best extraction efficiency, some important factors including the amount of Fe3O4@mSiO2-F17 microspheres added, adsorption time, type of elution solvent, eluting solvent volume and elution time were investigated. The ranges of the LOD were 0.02-0.05 ng mL(-1) for the six PFCs. The recovery of the optimized method varies from 83.13% to 92.42% for human serum samples.

  1. Facile synthesis of yolk-shell magnetic mesoporous carbon microspheres for efficient enrichment of low abundance peptides

    NASA Astrophysics Data System (ADS)

    Wan, Hao; Qin, Hongqiang; Xiong, Zhichao; Zhang, Weibing; Zou, Hanfa

    2013-10-01

    Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m2 g-1), a large pore volume (0.31 cm3 g-1), and a strong magnetic response (a saturation magnetization value of 34.57 emu g-1). As a result of the void between the core and the outer shell and the π-π stacking effect, adsorption capacity reached 191.64 mg g-1 by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the

  2. A facile synthesis of luminescent YVO4:Eu3+ hollow microspheres in virtue of template function of the SDS-PEG soft clusters

    NASA Astrophysics Data System (ADS)

    Wang, Juan; Yan, Yinglin; Hojamberdiev, Mirabbos; Ruan, Xiaoguang; Cai, Anjiang; Xu, Yunhua

    2012-08-01

    Hollow europium-doped yttrium orthovanadate (YVO4:Eu3+) microspheres were fabricated via a sodium dodecyl sulfate (SDS)-polyethylene glycol (PEG)-assisted hydrothermal technique. The as-synthesized hollow YVO4:Eu3+ microspheres were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). The obtained results showed that the morphology and size of the hollow microspheres have a strong dependence on the hydrothermal reaction time of the YVO4:Eu3+ powders. It is believed that the SDS-PEG clusters perform a function of dual soft-template that results in a unique template-induced secondary assembly in the one-pot synthesis of hollow YVO4:Eu3+ microspheres. The photoluminescence measurement revealed that the YVO4:Eu3+ powders with a spherical hollow shape have better red luminescence compared to the YVO4:Eu3+ solid microspheres. As a result, the controlled synthesis of hollow YVO4:Eu3+ microspheres not only has a great theoretical significance in studying the three-dimensional control and selective synthesis of inorganic materials but also benefits the potential applications based on hollow YVO4:Eu3+ microspheres owing to reducing the usage of expensive rare-earth elements.

  3. Composite microsphere-functionalized scaffold for the controlled release of small molecules in tissue engineering

    PubMed Central

    Pandolfi, Laura; Minardi, Silvia; Taraballi, Francesca; Liu, Xeuwu; Ferrari, Mauro; Tasciotti, Ennio

    2016-01-01

    Current tissue engineering strategies focus on restoring damaged tissue architectures using biologically active scaffolds. The ideal scaffold would mimic the extracellular matrix of any tissue of interest, promoting cell proliferation and de novo extracellular matrix deposition. A plethora of techniques have been evaluated to engineer scaffolds for the controlled and targeted release of bioactive molecules to provide a functional structure for tissue growth and remodeling, as well as enhance recruitment and proliferation of autologous cells within the implant. Recently, novel approaches using small molecules, instead of growth factors, have been exploited to regulate tissue regeneration. The use of small synthetic molecules could be very advantageous because of their stability, tunability, and low cost. Herein, we propose a chitosan–gelatin scaffold functionalized with composite microspheres consisting of mesoporous silicon microparticles and poly(dl-lactic-co-glycolic acid) for the controlled release of sphingosine-1-phospate, a small molecule of interest. We characterized the platform with scanning electron microscopy, Fourier transform infrared spectroscopy, and confocal microscopy. Finally, the biocompatibility of this multiscale system was analyzed by culturing human mesenchymal stem cells onto the scaffold. The presented strategy establishes the basis of a versatile scaffold for the controlled release of small molecules and for culturing mesenchymal stem cells for regenerative medicine applications. PMID:26977286

  4. Fabrication of novel magnetically separable BiOBr/CoFe2O4 microspheres and its application in the efficient removal of dye from aqueous phase by an environment-friendly and economical approach

    NASA Astrophysics Data System (ADS)

    Jiang, R.; Zhu, H.-Y.; Li, J.-B.; Fu, F.-Q.; Yao, J.; Jiang, S.-T.; Zeng, G.-M.

    2016-02-01

    Novel magnetically separable BiOBr/CoFe2O4 microspheres assembled from nanoparticles were successfully fabricated by a facile solvothermal method at 160 °C for 12 h. Then, BiOBr/CoFe2O4 microspheres were characterized via XRD, TEM, SEM, EDS and VSM. Congo red (CR) was selected as a pollutant model to evaluate the photocatalytic activities of BiOBr/CoFe2O4 microspheres. The value of coercivity (232 Oe) and the saturation magnetization (33.79 emu g-1) were obtained, which indicated that BiOBr/CoFe2O4 microspheres can be separated and recovered easily from the treated solution. What is more, by calculation, the initial rate constants of BiOBr/CoFe2O4 microspheres is about 1.45 times higher than that of the pure BiOBr, which resulted from superior adsorption and transfer performance to organic contaminants in aqueous systems. Four consecutive regeneration cycles demonstrated that the BiOBr/CoFe2O4 microspheres had high photostability under simulated solar light irradiation. According to the radical trapping experiments, the h+ radicals and O2rad - radicals were the two main active species that drive the photocolorization of CR pollutant by BiOBr/CoFe2O4 microspheres under simulated solar light irradiation. This work suggests that the BiOBr/CoFe2O4 microspheres may be a promising photocatalyst for photodegrading organic pollutants and environmental remediation.

  5. Remote controlled drug release from multi-functional Fe3O4/GO/Chitosan microspheres fabricated by an electrospray method.

    PubMed

    Li, Sheng; Xiao, Ling; Deng, Hongbing; Shi, Xiaowen; Cao, Qihua

    2017-03-01

    The construction of multifunctional microspheres for remote controlled drug release requires the exquisite selection of composite materials and preparation approaches. In this study, chitosan, an amino polysaccharide, was blended with inorganic nanocomponents, Fe3O4 and graphene oxide (GO) and electrosprayed to fabricate uniform microspheres with the diameters ranging from 100μm to 1100μm. An anti-cancer drug, doxorubicin (DOX), was loaded to the microspheres by an adsorption or embedding method. The microsphere is responsive to magnetic fields due to the presence of Fe3O4, and the incorporation of GO enhanced the drug loading capacity. The fast stimuli-responsive release of DOX can be facilely controlled by using NIR irradiation due to the strong photo-thermal conversion of Fe3O4 and GO. In addition, ultrasound was used as another external stimulus for DOX release. The results suggest the Fe3O4/GO/Chitosan microspheres fabricated by the electrospray method provide an efficient platform for remote controlled drug release, which may have potential applications in drug eluting microspheres.

  6. G-rich sequence-functionalized polystyrene microsphere-based instantaneous derivatization for the chemiluminescent amplified detection of DNA.

    PubMed

    Xin, Liang; Cao, Zhijuan; Lau, Choiwan; Kai, Masaaki; Lu, Jianzhong

    2010-01-01

    Herein, we develop a novel chemiluminescence (CL) approach with high sensitivity and excellent selectivity, by taking advantage of magnetic beads as preconcentration carriers and polystyrene microspheres as an amplification platform. Briefly, a 'sandwich-type' detection strategy is employed in our design, which involves capture probe DNA immobilized on the surface of carboxyl-terminated magnetic beads and multiple biotinylated reporter DNA self-assembled on the surface of streptavidin-modified polystyrene microspheres. The reporter DNA includes a guanine nucleobase-rich (G-rich) sequence domain for the generation of light and an additional tethered nucleic acid domain complementary with the target DNA. The CL signal is obtained via a novel instantaneous derivatization reaction between a specific CL reagent and the guanine nucleo-bases rich in the target and reporter DNA. As a result, we demonstrate that this DNA assay is reproducible, stable, easy to use, and can sensitively detect femtomolar target DNA related to anthrax lethal factors with excellent differentiation ability for single-base mismatched sequences. Overall, this new CL protocol couples the high sensitivity of CL analysis with effective magnetic separation for discriminating against unwanted constituents such as mismatched sequences, and hence, offers great promise for DNA hybridization analysis. Copyright (c) 2009 John Wiley & Sons, Ltd.

  7. Synthesis of multi-core-shell magnetic molecularly imprinted microspheres for rapid recognition of dicofol in tea.

    PubMed

    Yan, Hongyuan; Cheng, Xiaoling; Sun, Ning

    2013-03-20

    Magnetic multi-core-shell molecularly imprinted microspheres (Fe3O4@MIMs) based on multi-Fe3O4 nanoparticles as core structures and dummy imprinted materials as shell structures have been synthesized by a surface-imprinted technique using dichlorodiphenyltrichloroethane as the dummy template and were successfully used as a specific adsorbent for rapid isolation of trace levels of dicofol from teas. The resulting Fe3O4@MIMs were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometer, and thermogravimetric analysis. In comparison to the imprinted polymers prepared by the traditional polymerizations, the obtained Fe3O4@MIMs showed regularly spherical shape, porous morphologies, high saturation magnetization [56.8 electromagnetic units (emu)/g], and rapid response time (15 s). The as-synthesized Fe3O4@MIMs, which incorporated the excellent molecular recognition and magnetic separation properties, were successfully used as special adsorbents for rapid isolation and extraction of trace levels of dicofol and its analogues from a complicated tea matrix.

  8. Enzymatic synthesis of catechol and hydroxyl-carboxic acid functionalized chitosan microspheres for iron overload therapy.

    PubMed

    Brzonova, Ivana; Steiner, Walter; Zankel, Armin; Nyanhongo, Gibson S; Guebitz, Georg M

    2011-10-01

    Excess "free" iron which occurs under certain physiological conditions participates in the formation of toxic reactive oxygen species via the "fenton" chemistry. The reactive oxygen species oxidize biomolecules and have been implicated in many oxidative stress-related diseases. However, the ideal therapy for treating iron overload problems in humans has not yet been developed. In this study, the phenolic molecules catechol, caffeic acid, and 2,5-dihydroxybenzoic acid were successfully coupled to glucosamine as model substrate in a 1:1 ratio using laccase. Furthermore, coupling of these molecules onto chitosans of different sizes was demonstrated, resulting in decrease in -NH(2) groups as quantified via derivatization. A concomitant increase in iron-chelating capacity from below 3% to up to 70% upon phenolic functionalization was measured for the chitosans based on reduced ferrozine/Fe(2+) complex formation. Interesting these phenolic compounds seems to also participate as cross-linkers in producing characteristic microspheres. This work therefore opens-up new strategies aimed at developing a new generation of iron-chelating biomedical polymers.

  9. Preparation of thermoresponsive Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) magnetic composite microspheres with controlled shell thickness and its releasing property for phenolphthalein.

    PubMed

    Zhang, Baoliang; Zhang, Hepeng; Fan, Xinlong; Li, Xiangjie; Yin, Dezhong; Zhang, Qiuyu

    2013-05-15

    In this work, Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) (Fe3O4/P(AA-MMA-NIPAm)) thermoresponsive magnetic composite microspheres have been prepared by controlled radical polymerization in the presence of 1,1-diphenylethene (DPE). The shell thickness of thermosensitive polymer (PNIPAm), which was on the surface of the microspheres, can be controlled by using DPE method. The morphology and thermosensitive properties of the composite microspheres, polymerization mechanism of the shell were characterized by TEM, FTIR, VSM, Laser Particle Sizer, TGA, NMR, and GPC. The microspheres with narrow particle size distribution show high saturation magnetization and superparamagnetism. The thermosensitive properties of the composite microspheres can be adjusted indirectly via controlling the addition amount of monomer (NIPAm) in the second step during controlled radical polymerization. Phenolphthalein was chosen as a model drug to investigate drug release behavior of the thermoresponsive magnetic composite microspheres with different shell thickness. Controlled drug release testing reveals that the release behavior depends on the thickness of polymer on the surface of the microspheres. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. RNA aptamer-based electrochemical aptasensor for C-reactive protein detection using functionalized silica microspheres as immunoprobes.

    PubMed

    Wang, Junchun; Guo, Jinjin; Zhang, Junjun; Zhang, Wenjuan; Zhang, Yuzhong

    2017-09-15

    C-reactive protein (CRP) is a widely accepted biomarker of cardiovascular disease and inflammation. In this study, a RNA aptamer-based electrochemical sandwich type aptasensor for CRP detection was described using the functionalized silica microspheres as immunoprobes. Silica microspheres (Si MSs), which have good monodispersity and uniform shape, were firstly synthesized. The silica microspheres functionlized with gold nanoparticles (Au NPs) provided large surface area for immobilizing signal molecules (Zinc ions, Zn(2+)) and antibodies (Ab). RNA aptamers, which were specific recognized to CRP, were assembled on the surface of Au NPs modified electrode via gold-sulfur affinity. In the presence of CRP, a sandwich structure of aptamer-CRP-immunoprobe was formed. Square wave voltammetry (SWV) was employed to record the sensing signal, and a clearly reductive peak corresponding to Zn(2+) at about -1.16V (vs. SCE) was obtained. Under optimal conditions, the aptasensor showed wide linear range (0.005ngmL(-1) to 125ngmL(-1)) and low detection limit (0.0017ngmL(-1) at a signal-to-noise ratio of 3). Some possible interfering substance was also investigated, and the results obtained showed that the aptasensor possessed good selectivity. When the aptasensor was applied to real serum samples analysis, the satisfied results were obtained, indicating that the aptasensor possessed potential real application ability. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Hydrophilic Nb⁵⁺-immobilized magnetic core-shell microsphere--A novel immobilized metal ion affinity chromatography material for highly selective enrichment of phosphopeptides.

    PubMed

    Sun, Xueni; Liu, Xiaodan; Feng, Jianan; Li, Yan; Deng, Chunhui; Duan, Gengli

    2015-06-23

    Rapid and selective enrichment of phosphopeptides from complex biological samples is essential and challenging in phosphorylated proteomics. In this work, for the first time, niobium ions were directly immobilized on the surface of polydopamine-coated magnetic microspheres through a facile and effective synthetic route. The Fe3O4@polydopamine-Nb(5+) (denoted as Fe3O4@PD-Nb(5+)) microspheres possess merits of high hydrophilicity and good biological compatibility, and demonstrated low limit of detection (2 fmol). The selectivity was also basically satisfactory (β-casein:BSA=1:500) to capture phosphopeptides. They were also successfully applied for enrichment of phosphopeptides from real biological samples such as human serum and nonfat milk. Compared with Fe3O4@PD-Ti(4+) microspheres, the Fe3O4@PD-Nb(5+) microspheres exhibit superior selectivity to multi-phosphorylated peptides, and thus may be complementary to the conventional IMAC materials. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Magnetoresponsive Photonic Microspheres with Structural Color Gradient.

    PubMed

    Lee, Seung Yeol; Choi, Jongkook; Jeong, Jong-Ryul; Shin, Jung H; Kim, Shin-Hyun

    2017-02-06

    Photonic Janus particles are created by alternately sputtering silica and titania on microspheres in order to obtain a structural color gradient. In addition, the microspheres are rendered magnetoresponsive. The Janus microspheres with optical and magnetic anisotropy enable on-demand control over orientation and structural color through manipulation of an external magnetic field, thereby being useful as active color pigments for reflection-mode displays.

  13. Fabrication of silver-coated silica microspheres through mussel-inspired surface functionalization.

    PubMed

    Wang, Wencai; Jiang, Yi; Liao, Yuan; Tian, Ming; Zou, Hua; Zhang, Liqun

    2011-06-15

    A facile method was developed to prepare silica-silver core-shell composite microspheres with continuous, compact, and conductive silver layers. The procedure involves dopamine oxidative self-polymerization and electroless plating. The poly(dopamine) layer was used as the chemi-sorption sites for silver ions and promoted the silver deposition. The electroless plating procedure involves a combination of surface activation, seeding growth, and deposition. The chemical composition and the crystal structure of the silica-silver core-shell composite microspheres were studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. In addition, the surface morphology and chemical composition of each composite microsphere were confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The results demonstrated that the silver layer on the silica surface was continuous and compacted.

  14. Ultrathin-yttrium phosphate-shelled polyacrylate-ferriferrous oxide magnetic microspheres for rapid and selective enrichment of phosphopeptides.

    PubMed

    Sun, Ye; Wang, He-Fang

    2013-11-05

    Rapid and selective enrichment of phosphopeptides from complex biological samples is essential and challenging in phosphorylated proteomics. We present the direct growth of the ultrathin YPO4 shell on the surface of polyacrylate capped secondary Fe3O4 microspheres (PA-Fe3O4@YPO4) for the rapid and selective trapping phosphopeptides from complex samples. The prepared PA-Fe3O4@YPO4 could be rapidly harvested in the presence of an applied magnetic field and easily re-dispersed in solutions after removing the external magnet. The ultrathin YPO4 shell on super-hydrophilic PA-Fe3O4 has the advantages of fast adsorption/desorption dynamics and low non-specific adsorption, thus trapping of phosphopeptides from the tryptic digests mixture of β-casein/BSA with molar ratio of 1/300 is achieved in 20s adsorption/desorption time. Two phosphopeptides can still be detected with a signal to noise ratio (S/N) over 3 when the amount of β-casein was as low as 8 fmol.

  15. Novel molecular imprinted polymers over magnetic mesoporous silica microspheres for selective and efficient determination of protocatechuic acid in Syzygium aromaticum.

    PubMed

    Xie, Lianwu; Guo, Junfang; Zhang, Yuping; Hu, Yunchu; You, Qingping; Shi, Shuyun

    2015-07-01

    Improving sites accessibility can increase the binding efficiency of molecular imprinted polymers (MIPs). In this work, we firstly synthesized MIPs over magnetic mesoporous silica microspheres (Fe3O4@mSiO2@MIPs) for the selective recognition of protocatechuic acid (PCA). The resulting Fe3O4@mSiO2@MIPs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT-IR), thermo-gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and vibration sample magnetometer (VSM), and evaluated by adsorption isotherms/kinetics and competitive adsorption. The maximum adsorption capacity of PCA on Fe3O4@mSiO2@MIPs was 17.2mg/g (2.3 times that on Fe3O4@SiO2@MIPs). In addition, Fe3O4@mSiO2@MIPs showed a short equilibrium time (140min), rapid magnetic separation (5s) and high stability (retained 94.4% after six cycles). Subsequently, Fe3O4@mSiO2@MIPs were successfully applied for the selective and efficient determination of PCA (29.3μg/g) from Syzygium aromaticum. Conclusively, we combined three advantages into Fe3O4@mSiO2@MIPs, namely, Fe3O4 core for quick separation, mSiO2 layer for enough accessible sites, and surface imprinting MIPs for fast binding and excellent selectivity, to extract PCA from complex systems.

  16. Magnetic solid-phase extraction of phthalate esters (PAEs) in apparel textile by core-shell structured Fe3O4@silica@triblock-copolymer magnetic microspheres.

    PubMed

    Xu, Mei; Liu, Minhua; Sun, Meirong; Chen, Kun; Cao, Xiujun; Hu, Yaoming

    2016-04-01

    In this paper, novel core-shell structured magnetic Fe3O4/silica nanocomposites with triblock-copolymer grafted on their surface (Fe3O4@SiO2@MDN) were successfully fabricated by combining a sol-gel method with a seeded aqueous-phase radical copolymerization approach. Owing to the excellent characteristics of the strong magnetic responsivity, outstanding hydrophilicity and abundant π-electron system, the obtained core-shell structured microspheres showed great potential as a magnetic solid phase extraction (MSPE) adsorbent. Several kinds of phthalate esters (PAEs) were selected as model analytes to systematically evaluate the applicability of adsorbents for extraction followed by gas chromatography-mass spectrometry (GC-MS) analyses. Various parameters, including adsorbents amounts, adsorption time, species of eluent, and desorption time were optimized. Under the optimized conditions, Validation experiments such as recovery, reproducibility, and limit of detection were carried on and showed satisfactory results. The analysis method showed excellent linearity with a wide range of 0.2-10mg/kg (R(2)>0.9974) and low limits of detection (LOD) of 0.02-0.09 mg/kg (S/N=3). Ultimately, the novel magnetic adsorbents were successfully employed to detect the PAEs in apparel textile samples. And the results indicated that this novel approach brought forward in the present work offered an attractive alternative for rapid, efficient and sensitive MSPE for PAEs compounds.

  17. Magnetic Wood Achieving a Harmony between Magnetic and Woody Functions

    NASA Astrophysics Data System (ADS)

    Oka, Hideo

    Magnetic wood, which was first introduced and developed by the Oka group in 1991, achieves a good balance of both woody and magnetic functions through the active addition of magnetic characteristics to the wood itself. In addition to showing magnetic characteristics, this magnetic wood also offers a woody texture, low specific gravity, humidity control, acoustic absorption and is very easy to process.

  18. Ultrasensitive sandwich-type electrochemical immunosensor based on a novel signal amplification strategy using highly loaded palladium nanoparticles/carbon decorated magnetic microspheres as signal labels.

    PubMed

    Ji, Lei; Guo, Zhankui; Yan, Tao; Ma, Hongmin; Du, Bin; Li, Yueyun; Wei, Qin

    2015-06-15

    An ultrasensitive sandwich-type electrochemical immunosensor for quantitative detection of alpha fetoprotein (AFP) was proposed based on a novel signal amplification strategy in this work. Carbon decorated Fe3O4 magnetic microspheres (Fe3O4@C) with large specific surface area and good adsorption property were used as labels to anchor palladium nanoparticles (Pd NPs) and the secondary antibodies (Ab2). Pd NPs were loaded on Fe3O4@C to obtain Fe3O4@C@Pd with core-shell structure by electrostatic attraction, which were further used to immobilize Ab2 due to the bonding of Pd-NH2. A signal amplification strategy was the noble metal nanoparticles, such as Pd NPs, exhibiting high electrocatalytic activities toward hydrogen peroxide (H2O2) reduction. This signal amplification was novel not only because of the great capacity, but also the ease of magnetic separation from the sample solution based on their magnetic property. Moreover, carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) were used for the immobilization of primary antibodies (Ab1). Therefore, high sensitivity could be realized by the designed immunosensor based on this novel signal amplification strategy. Under optimal conditions, the immunosensor exhibited a wide linear range of 0.5 pg/mL to 10 ng/mL toward AFP with a detection limit of 0.16 pg/mL (S/N=3). Moreover, it revealed good selectivity, acceptable reproducibility and stability, indicating a potential application in clinical monitoring of tumor biomarkers. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Potentiometric Response Characteristics of Membrane-Based Cs + -Selective Electrodes Containing Ionophore-Functionalized Polymeric Microspheres

    DOE PAGES

    Peper, Shane; Gonczy, Chad

    2011-01-01

    Csmore » + -selective solvent polymeric membrane-based ion-selective electrodes (ISEs) were developed by doping ethylene glycol-functionalized cross-linked polystyrene microspheres (P-EG) into a plasticized poly(vinyl chloride) (PVC) matrix containing sodium tetrakis-(3,5-bis(trifluoromethyl)phenyl) borate (TFPB) as the ion exchanger. A systematic study examining the effects of the membrane plasticizers bis(2-ethylhexyl) sebacate (DOS), 2-nitrophenyl octyl ether (NPOE), and 2-fluorophenyl nitrophenyl ether (FPNPE) on the potentiometric response and selectivity of the corresponding electrodes was performed. Under certain conditions, P-EG-based ion-selective electrodes (ISEs) containing TFPB and plasticized with NPOE exhibited a super-Nernstian response between 1 × 10 − 3 and 1 × 10 − 4  M+ , a response characteristic not observed in analogous membranes plasticized with either DOS or FPNPE. Additionally, the performance of P-EG-based ISEs was compared to electrodes based on two mobile ionophores, a neutral lipophilic ethylene glycol derivative (ethylene glycol monooctadecyl ether (U-EG)) and a charged metallacarborane ionophore, sodium bis(dicarbollyl)cobaltate(III) (CC). In general, P-EG-based electrodes plasticized with FPNPE yielded the best performance, with a linear range from 10 -1 –10 -5  M+ , a conventional lower detection limit of 8.1 × 10 − 6  M+ , and a response slope of 57.7 mV/decade. The pH response of P-EG ISEs containing TFPB was evaluated for membranes plasticized with either NPOE or FPNPE. In both cases, the electrodes remained stable throughout the pH range 3–12, with only slight proton interference observed below pH 3.« less

  20. Memory functions of magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Koshibae, Wataru; Kaneko, Yoshio; Iwasaki, Junichi; Kawasaki, Masashi; Tokura, Yoshinori; Nagaosa, Naoto

    2015-05-01

    We study, by microsimulation on the chiral magnets, the elementary functions of magnetic skyrmions and the design principles of skyrmionic memory devices. The external stimuli, such as local heating, magnetic field, electric field and electric current, trigger the creation and annihilation of the skyrmion. These procedures, corresponding to the writing and erasing operations, are achieved typically within of the order of nano or pico seconds. We also examine the current driven motion of the skyrmions and find that the gyro-dynamics, which is induced by the topological nature of the skyrmion, leads to the variety of useful functions including the remarkable enhancement of the spin-transfer-torque effect. These features are shown to be advantageous for (a) high-density data-storage, (b) nonvolatile memory, and (c) ultra-low current and energy cost manipulation.

  1. [Pharmacokinetics and distribution of 5-Fu magnetic albumin deuto-microsphere in normal and tumor-bearing mice].

    PubMed

    Xu, Rong; Shi, Shao-Jun; Zhou, Shun-Chang; Zheng, Jian-Wei; Chen, Hui; Zou, Sheng-Quan; Zeng, Fan-Dian

    2007-01-01

    To observe the pharmacokinetic and tissue-distribution characters of 5-flourouracil magnetic albumin deuto-microsphere (5-Fu-MAD) in normal and tumor-bearing mice, HPLC method for the determination of 5-Fu in plasma and tissues was established and applied to determine 5-Fu in mouse plasma and tissue samples. A Flame atomic absorption spectrometer was used to detect the iron concentration in mouse tissue. Plasma concentration-time curves of free 5-Fu, 5-Fu-MAD and 5-Fu-MAD plus the magnetic frame (MF) conformed to two compartment model of first order absorption and they had C(max) of 34.9, 7.95 and 5.97 mg x L(-1); T1/2 (Ke) of 22.26, 76.0 and 124.6 min, V(d) of 3.28, 30.7 and 66.1 L x kg; AUC(0-t), of 233.9, 78.3 and 50.2 mg x min x L(-1); AUC(0-infinity) of 237.2, 89.3 and 68.1 mg x min x L(-1), respectively. The distribution of 5-Fu and iron was the highest in the plenty blood perfusion organs like the liver, tumor, spleen and lung, while lower in the kidney and heart and lowest in brain and muscle. The tissue distribution of muscle and tumor increased significantly when a magnetic frame was inserted there. The pharmacokinetics and tissue distribution of 5-Fu-MAD exhibited sustained-release and target characteristics.

  2. Thermo-responsive polymer tethered metal-organic framework core-shell magnetic microspheres for magnetic solid-phase extraction of alkylphenols from environmental water samples.

    PubMed

    Jia, Yuqian; Su, Hao; Wong, Y-L Elaine; Chen, Xiangfeng; Dominic Chan, T-W

    2016-07-22

    In this work, the thermo-responsive polymer PNIPAM tethered to Fe3O4@SiO2@MOF core-shell magnetic microspheres was first synthesized by a surface-selective post-synthetic strategy and underwent highly efficient magnetic solid-phase extraction (MSPE) of alkylphenols from aqueous samples. Alkylphenols, including 4-tert-octylphenol (OP) and 4-n-nonylphenol (NP), were selected as target compounds. The sample quantification was carried out using LC-MS/MS in multiple reaction monitor (MRM) mode. Under optimal working conditions, the developed method showed good linearity in the range of 5-1000ngL(-1), a low limit of detection (1.5ngL(-1)), and good repeatability (relative standard deviation, <8%, n=5) for NP and OP. Owning to the hydrophilic/hydrophobic switchable properties of the nanocomposite, high recoveries (78.7-104.3%) of alkylphenols were obtained under different extraction conditions. The levels of OP and NP in environmental samples collected from local river, lake and pond waters were analyzed using the developed method. It was believed that the synthesized material with the thermo-responsive coating, large surface areas and magnetic properties should have great potential in the extraction and removal of alkylphenols from environmental samples.

  3. Upconversion Nanoparticles and Monodispersed Magnetic Polystyrene Microsphere Based Fluorescence Immunoassay for the Detection of Sulfaquinoxaline in Animal-Derived Foods.

    PubMed

    Hu, Gaoshuang; Sheng, Wei; Zhang, Yan; Wang, Junping; Wu, Xuening; Wang, Shuo

    2016-05-18

    A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L(-1) in buffer and 0.5 μg kg(-1) in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24-25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods.

  4. Structural, optical, and magnetic studies of manganese-doped zinc oxide hierarchical microspheres by self-assembly of nanoparticles

    PubMed Central

    2012-01-01

    In this study, a series of manganese [Mn]-doped zinc oxide [ZnO] hierarchical microspheres [HMSs] are prepared by hydrothermal method only using zinc acetate and manganese acetate as precursors and ethylene glycol as solvent. X-ray diffraction indicates that all of the as-obtained samples including the highest Mn (7 mol%) in the crystal lattice of ZnO have a pure phase (hexagonal wurtzite structure). A broad Raman spectrum from as-synthesized doping samples ranges from 500 to 600 cm-1, revealing the successful doping of paramagnetic Mn2+ ions in the host ZnO. Optical absorption analysis of the samples exhibits a blueshift in the absorption band edge with increasing dopant concentration, and corresponding photoluminescence spectra show that Mn doping suppresses both near-band edge UV emission and defect-related blue emission. In particular, magnetic measurements confirm robust room-temperature ferromagnetic behavior with a high Curie temperature exceeding 400 K, signifying that the as-formed Mn-doped ZnO HMSs will have immense potential in spintronic devices and spin-based electronic technologies. PMID:22296968

  5. Synthesis of biocompatible, mesoporous Fe(3)O(4) nano/microspheres with large surface area for magnetic resonance imaging and therapeutic applications.

    PubMed

    Xuan, Shouhu; Wang, Feng; Lai, Josie M Y; Sham, Kathy W Y; Wang, Yi-Xiang J; Lee, Siu-Fung; Yu, Jimmy C; Cheng, Christopher H K; Leung, Ken Cham-Fai

    2011-02-01

    This article reports the fabrication of mesoporous Fe(3)O(4) nano/microspheres with a high surface area value (163 m(2)/g, Brunauer-Emmett-Teller) and demonstrates their use for drug loading, release, and magnetic resonance imaging (MRI). These monodispersed, mesoporous Fe(3)O(4) nano/microspheres with controllable average sizes ranging from 50 to 200 nm were synthesized using a Fe(3)O(4)/poly(acrylic acid) hybrid sphere template and subsequent silica shell formation and removal. We found that the SiO(2) coating is a crucial step for the successful synthesis of uniform mesoporous Fe(3)O(4) nano/microspheres. The as-synthesized mesoporous Fe(3)O(4) nanospheres show a high magnetic saturation value (M(s) = 48.6 emu/g) and could be used as MRI contrast agents (r(2) = 36.3 s(-1) mM(-1)). Trypan blue exclusion and MTT assay (see Supporting Information ) cytotoxicity analyses of the nanospheres based on HepG2 and MDCK cells showed that the products were biocompatible, with a lower toxicity than lipofectamine (positive control). Hydrophilic ibuprofen and hydrophobic zinc(II) phthalocyanine drug loading into mesoporous Fe(3)O(4) nanospheres and selected release experiments were successfully achieved. The potential use of mesoporous Fe(3)O(4) nanospheres in biomedical applications, in light of the nano/microspheres' efficient drug loading and release, MRI, and low cytotoxicity, has been demonstrated. It is envisaged that mesoporous Fe(3)O(4) nanospheres can be used as drug carriers and MRI contrast agents for the reticuloendothelial system; they can also be delivered locally, such as via a selective catheter.

  6. Effects of nefiracetam on spatial memory function and acetylcholine and GABA metabolism in microsphere-embolized rats.

    PubMed

    Fukatsu, Tomoko; Miyake-Takagi, Keiko; Nagakura, Akira; Omino, Kunio; Okuyama, Noriko; Ando, Tsuyoshi; Takagi, Norio; Furuya, Yoshitaka; Takeo, Satoshi

    2002-10-18

    The present study aimed to determine whether nefiracetam, N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, a cognition enhancer, has an effect on learning and memory function in sustained cerebral ischemia, and whether the effect, if any, may accompany modification of the cholinergic or gamma-aminobutyric acid (GABA)ergic system, which are conceived to be involved in the learning and memory function, in the ischemic brain. Sustained cerebral ischemia was induced by the injection of 700 microspheres into the right hemisphere of the rat. The animals were treated once daily with 10 mg/kg nefiracetam p.o. from 15 h after the operation to either 10 days for the water maze study, or 3 or 5 days after the operation for neurochemical examination. Microsphere-embolized rats showed stroke-like symptoms 15 h after the operation and lengthened the escape latency in the water maze task on days 7-10, suggesting a spatial learning dysfunction. The delayed treatment did not reduce the stroke-like symptoms, but effectively shortened the escape latency. The animals at days 3 and 5 after the operation showed decreases in acetylcholine content and choline acetyltransferase activity, which were not prevented by nefiracetam. The microsphere-embolized rats showed decreases in GABA content and glutamic acid decarboxylase activity. The delayed treatment appreciably restored GABA content in the hippocampus on day 5 and reversed glutamic acid decarboxylase activity in both brain regions on day 5. These results suggest that the GABAergic activity rather than the cholinergic activity may be, at least in part, involved in the pharmacological effects of nefiracetam in the ischemic brain.

  7. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1986-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  8. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1987-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  9. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1983-01-01

    Microspheres of acrolein homopolymers and co-polymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  10. Immunofluorescence detection methods using microspheres

    NASA Astrophysics Data System (ADS)

    Szurdoki, Ferenc; Michael, Karri L.; Agrawal, Divya; Taylor, Laura C.; Schultz, Sandra L.; Walt, David R.

    1999-01-01

    Microsphere-based immunoassays were devised for compounds of agricultural and biomedical interest (e.g., digoxin, theophylline, and zearalenone). Commercially available microspheres with surface functional groups for chemical derivatization were used as solid carriers. After immobilizing the target substances, the surface of the haptenized microspheres was blocked by a protein to reduce aspecific binding. Competitive immunoassays were performed using the functionalized microspheres and antibodies labeled with horseradish peroxidase. Immunofluorescence signal amplification was achieved by enzyme-catalyzed reporter deposition (CARD). An epifluorescence microscope, a CCD camera interfaced with a computer, and microscopy image analysis software were employed for quantitative detection of fluorescent light emitted from individual microspheres. Integration of several such immunoassays and application of an optical encoding method enabled multianalyte determination. These immunoassays can also be utilized in an immunosensor array format. This immunoarray format could facilitate miniaturization and automation of multianalyte immunoassays.

  11. Sequential Enrichment with Titania-coated Magnetic Mesoporous Hollow Silica Microspheres and Zirconium Arsenate-modified Magnetic Nanoparticles for the Study of Phosphoproteome of HL60 Cells

    PubMed Central

    Yu, Qiong-Wei; Li, Xiao-Shui; Xiao, Yongsheng; Guo, Lei; Zhang, Fan; Cai, Qian; Feng, Yu-Qi; Yuan, Bi-Feng; Wang, Yinsheng

    2014-01-01

    As one of the most important types of post-translational modifications, reversible phosphorylation of proteins plays crucial roles in a large number of biological processes. However, owing to the relatively low abundance and dynamic nature of phosphorylation and the presence of the unphosphorylated peptides in large excess, phosphopeptide enrichment is indispensable in large-scale phosphoproteomic analysis. Metal oxides including titanium dioxide have become prominent affinity materials to enrich phosphopeptides prior to their analysis using liquid chromatography-mass spectrometry (LC-MS). In the current study, we established a novel strategy, which encompassed strong cation exchange chromatography, sequential enrichment of phosphopeptides using titania-coated magnetic mesoporous hollow silica microspheres (TiO2/MHMSS) and zirconium arsenate-modified magnetic nanoparticles (ZrAs-Fe3O4@SiO2), and LC-MS/MS analysis, for the proteome-wide identification of phosphosites of proteins in HL60 cells. In total, we were able to identify 11579 unique phosphorylation sites in 3432 unique proteins. Additionally, our results suggested that TiO2/MHMSS and ZrAs-Fe3O4@SiO2 are complementary in phosphopeptide enrichment, where the two types of materials displayed preferential binding of peptides carrying multiple and single phosphorylation sites, respectively. PMID:25262027

  12. An interference-free and label-free sandwich-type magnetic silicon microsphere -rGO-based probe for fluorescence detection of microRNA.

    PubMed

    Li, Shiyu; He, Kui; Liao, Rong; Chen, Chunyan; Chen, Xiaoming; Cai, Changqun

    2017-11-01

    An interference-free and label-free sensing platform was developed for the highly sensitive detection of microRNA-21 (miRNA-21) in vitro by magnetic silicon microsphere (MNP)-reduced graphene oxide (rGO)-based sandwich probe. In this method, DNA capture probes (P1) were connected with MNPs at the 5' end and hybridized with completely complementary target miRNA. Subsequently, rGO was retained and induced the fluorescence quenching in the supernatant. Through the magnetic separation, the supernatant environment was simplified and the interference to analytical signal was eliminated. When DNA capture probe-modified magnetic silicon microspheres (MNP-P1) were adsorbed through rGO in the absence of a target and formed a sandwich structure, the formed nanostructure was easily removed from the solution by a magnetic field and the fluorescence intensity was maximally recovered. This proposed strategy, which both overcame the expensive and cumbersome fluorescent labeling, and eliminated interference to analytical signal for guaranteeing high signal-to-background ratio, exhibited high sensitivity with a detection limit as low as 0.098nM and special selectivity toward miRNA-21. The method was potentially applicable for not only detection of miRNA-21 but also various biomarker analyses just by changing capture probes. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Modeling the Formation of Polyimide Microspheres

    NASA Technical Reports Server (NTRS)

    Pipes, R. B.; Weiser, E. S.; Gonsoulin, B.; Hubert, P.

    2002-01-01

    High temperature polyimide microspheres have been developed from polyimide solid residuum by a simple inflation process. Microspheres have been fabricated from several polyimide precursors through the use of a circulating air oven. Microsphere formation and final physical property characterization have been limited to simple mechanical and thermal testing. The present paper focuses on developing an understanding of microsphere formation through simple geometric rules for an incompressible polymeric material and microscopic observations of precursor residuum inflation. Inflation kinematics of the hollow polyimide microspheres as a function of time and temperature is discussed.

  14. Efficient removal and environmentally benign detoxification of Cr(VI) in aqueous solutions by Zr(IV) cross-linking chitosan magnetic microspheres.

    PubMed

    Chen, Xiumei; Zhang, Wengang; Luo, Xueli; Zhao, Fan; Li, Yixuan; Li, Ronghua; Li, Zhonghong

    2017-10-01

    Zirconium(IV) cross-linking chitosan (CTS) magnetic microspheres (Fe3O4@Zr-CTS) as a recoverable adsorbent were synthesized through the coordination reaction between zirconium oxychloride and CTS biopolymeric matrix for efficient adsorption and simultaneous detoxification of hexavalent chromium, Cr(VI), in aqueous solutions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the formation of core@shell magnetite microspheres. X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) verified the crosslinking of Zr(IV) to CTS on the microspheres. Batch Cr(VI) adsorption performances of the resultant Fe3O4@Zr-CTS microspheres revealed that the maximum adsorption capacity of 280.97 mg/g were achieved under pH 4.0 at 298 K. The XPS analyses indicated that 61.1% of the adsorbed Cr(VI) was reduced to Cr(III) due to the oxidization of alcoholic groups on C-6 in CTS which served as electron donors to carbonyl groups. The adsorbent showed preferential Cr(VI) adsorption with the existence of co-existing cations (K(+), Na(+), Cu(2+), Zn(2+), Ca(2+), Mg(2+)) and anions (NO3(-), Cl(-), SO4(2-), CO3(2-)). The adsorbent exhibited excellent reusability, lower the effluent Cr(VI) contents down to the ppb level, which satisfied the drinking water standard recommended by the World Health Organization and was a promising candidate for water purification. Copyright © 2017. Published by Elsevier Ltd.

  15. Development of novel magnetic solid phase extraction materials based on Fe3O4/SiO2/poly(acrylamide-N,N'-methylene bisacrylamide)-Pluronic L64 composite microspheres and their application to the enrichment of natamycin.

    PubMed

    Tian, Miaomiao; Zou, Yongcun; Zhou, Shaoyan; Wang, Tianpeng; Lv, Xueju; Jia, Qiong

    2015-12-15

    Novel magnetic adsorbents based on Fe3O4/SiO2/poly(acrylamide-N,N'-methylene bisacrylamide) magnetic microspheres modified with non-ionic triblock copolymer surfactant were successfully prepared as a magnetic solid phase extraction adsorbent for the determination of trace natamycin in jam samples. The adsorbent was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transformed infrared spectroscopy, vibrating sample magnetometer, and X-ray diffractometer analysis, confirming that Pluronic L64 was effectively functionalized on the magnetic materials. Various experimental parameters affecting the extraction capacity were investigated including adsorbent amount, extraction time, desorption time, sample pH, and ionic strength. For recovery evaluations, the jam samples were spiked at two concentration levels of 100 and 200μgkg(-1) of natamycin and the recovery values were in the range of 78.8-93.4%. The relative standard deviations (RSD) for the recoveries were less than 3.5%. The novel magnetic solid phase extraction method provided several advantages, such as simplicity, low environmental impact, convenient extraction procedure, and short analysis time when used for natamycin analysis.

  16. Metal-organic framework UiO-66 modified magnetite@silica core-shell magnetic microspheres for magnetic solid-phase extraction of domoic acid from shellfish samples.

    PubMed

    Zhang, Wenmin; Yan, Zhiming; Gao, Jia; Tong, Ping; Liu, Wei; Zhang, Lan

    2015-06-26

    Fe3O4@SiO2@UiO-66 core-shell magnetic microspheres were synthesized and characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry, nitrogen adsorption porosimetry and zeta potential analyzer. The synthesized Fe3O4@SiO2@UiO-66 microspheres were first used for magnetic solid-phase extraction (MSPE) of domoic acid (DA) in shellfish samples. Combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), a fast, simple and sensitive method for the determination of DA was established successfully. Under the optimized conditions, the developed method showed short analysis time, good linearity (r(2) = 0.9990), low limit of detection (1.45 pg mL(-1); S/N = 3:1), low limit of quantification (4.82 pg mL(-1); S/N = 10:1), and good extraction repeatability (RSD ≤ 5.0%; n = 5). Real shellfish samples were processed using the developed method, and trace level of DA was detected. The results demonstrate that Fe3O4@SiO2@UiO-66 core-shell magnetic microspheres are the promising sorbents for rapid and efficient extraction of polar analytes from complex biological samples.

  17. Surface modification of PLGA microspheres.

    PubMed

    Müller, M; Vörös, J; Csúcs, G; Walter, E; Danuser, G; Merkle, H P; Spencer, N D; Textor, M

    2003-07-01

    Microspheres made of poly(lactic-co-glycolic acid) (PLGA) are biocompatible and biodegradable, rendering them a promising tool in the context of drug delivery. However, nonspecific adsorption of plasma proteins on PLGA micro- and nanospheres is a main limitation of drug targeting. Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG), physisorbed on flat metal oxide surfaces, has previously been shown to suppress protein adsorption drastically. The goal of our work was to characterize the efficiency of the protein repellent character of PLL-g-PEG on PLGA microspheres and to show the feasibility of introducing functional groups on the PLGA microspheres via functionalized PLL-g-PEG. To quantify the adsorbed amount of protein, a semiquantitative method that uses confocal laser scanning microscopy (CLSM) was applied. The first part of the experiment confirms the feasibility of introducing specific functional groups on PLL-g-PEG-coated PLGA microspheres. In the second part of the experiment, PLL-g-PEG-coated PLGA microspheres show a drastic decrease of adsorbed proteins by two orders of magnitude in comparison to uncoated PLGA microspheres. Low protein-binding, functionalizable microspheres provide a fundamental basis for the design of drug delivery and biosensor systems. Copyright 2003 Wiley Periodicals, Inc.

  18. Covalent immobilization of lipases on monodisperse magnetic microspheres modified with PAMAM-dendrimer

    NASA Astrophysics Data System (ADS)

    Zhu, Weiwei; Zhang, Yimei; Hou, Chen; Pan, Duo; He, Jianjun; Zhu, Hao

    2016-02-01

    This paper reported an immobilization of Candida rugosa lipase (CRL) onto PAMAM-dendrimer-grafted magnetic nanoparticles synthesized by a modified solvothermal reduction method. The dendritic magnetic nanoparticles were amply characterized by several instrumental measurements, and the CRL was covalently anchored on the three generation supports with glutaraldehyde as coupling reagent. The amount of immobilized enzyme was up to 150 mg/g support and the factors related with the enzyme activity were investigated. The immobilization of lipase improved their performance in wider ranges of pH and temperature. The immobilized lipase exhibited excellent thermal stability and reusability in comparison with free enzyme and can be reused 10 cycles with the enzymatic activity remained above 90 %. The properties of lipase improved obviously after being immobilized on the dendritic supports. The inactive immobilized lipase could be regenerated with glutaraldehyde and Cu2+, respectively. This synthetic strategy was facile and eco-friendly for applications in lipase immobilization.

  19. Hydrothermal synthesis of magnetic mesoporous carbon microspheres from carboxymethylcellulose and nickel acetate

    NASA Astrophysics Data System (ADS)

    Wu, Qiong; Li, Wei; Tan, Jia; Nan, Xi; Liu, Shouxin

    2015-03-01

    Paramagnetic mesoporous carbon spheres with diameters of 1-3 μm were synthesized through the hydrothermal carbonization of carboxymethylcellulose with nickel acetate, followed by high-temperature carbonization in a N2 atmosphere. Monodisperse Ni particles of average size of 2-5 nm were doped into the carbon matrix, and covered the entrances of pores. Ni particles existed as metallic nickel and nickel oxide with ordered lattice structures. The effect of Ni content on the specific surface area, mesopore percentage, and magnetic and adsorption properties were investigated. The highest vitamin B12 adsorption capacity of 103 mg/g was achieved for the sample prepared using 0.04 g of nickel acetate. The Freundlich and Langmuir isotherm models were used to determine the equilibrium uptakes of vitamin B12. Vitamin B12 was physically adsorbed as a monolayer on the carbon spheres. The carbon spheres were easily separated on account of their magnetism.

  20. Pseudomorphic synthesis of monodisperse magnetic mesoporous silica microspheres for selective enrichment of endogenous peptides.

    PubMed

    Zhu, Gang-Tian; Li, Xiao-Shui; Gao, Qiang; Zhao, Ning-Wei; Yuan, Bi-Feng; Feng, Yu-Qi

    2012-02-10

    In this work, we describe a novel synthetic strategy of magnetic mesoporous silica spheres (Fe3O4@mSiO2) for the selective enrichment of endogenous peptides. Fe3O4 particles were coated with silica shell by a sol-gel method, followed by pseudomorphic synthesis to transform nonporous silica shell into ordered mesoporous silica shell. The core/shell structure and mesostructure were individually fabricated in two steps, which can be expedient to independently optimize the properties of monodispersion, magnetization and mesostructure. Actually, it was confirmed that the produced Fe3O4@mSiO2 particles possess good monodispersion, high magnetization, superparamagnetism, uniform accessible mesopores, and large surface area and pore volume. With these good properties, Fe3O4@mSiO2 spheres were applied to the rapid enrichment of peptides. Based on the size-exclusion mechanism and hydrophobic interaction with siloxane bridge group mainly on the surface of inside pores, Fe3O4@mSiO2 can selectively capture peptides and exclude high-MW proteins and salts. Furthermore, peptides in human plasma were successfully enriched by Fe3O4@mSiO2. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. [Presurgical functional magnetic resonance imaging].

    PubMed

    Stippich, C

    2010-02-01

    Functional magnetic resonance imaging (fMRI) is an important and novel neuroimaging modality for patients with brain tumors. By non-invasive measurement, localization and lateralization of brain activiation, most importantly of motor and speech function, fMRI facilitates the selection of the most appropriate and sparing treatment and function-preserving surgery. Prerequisites for the diagnostic use of fMRI are the application of dedicated clinical imaging protocols and standardization of the respective imaging procedures. The combination with diffusion tensor imaging (DTI) also enables tracking and visualization of important fiber bundles such as the pyramidal tract and the arcuate fascicle. These multimodal MR data can be implemented in computer systems for functional neuronavigation or radiation treatment. The practicability, accuracy and reliability of presurgical fMRI have been validated by large numbers of published data. However, fMRI cannot be considered as a fully established modality of diagnostic neuroimaging due to the lack of guidelines of the responsible medical associations as well as the lack of medical certification of important hardware and software components. This article reviews the current research in the field and provides practical information relevant for presurgical fMRI.

  2. Assembly of ordered microsphere arrays: Platforms for microarrays

    NASA Astrophysics Data System (ADS)

    Xu, Wanling

    Microarrays are powerful tools in gene expression assessment, protein profiling, and protein function screening, as well as cell and tissue analysis. With thousands of small array spots assembled in an ordered array, these small devices makes it possible to screen for multiple targets in a fast, parallel, high-throughput manner. The well-developed technology of DNA microarrays, also called DNA chips, has proved successful in all kinds of biological experiments, including the human genome-sequencing project. The development of protein arrays has lagged behind that of DNA arrays mainly because of the greater complexity of proteins. Some parts of the microarray technology can be transplanted into the realm of protein arrays, while others cannot. The challenges from the complexity of protein targets demand more robust and powerful devices. Traditional planar arrays, in which proteins bind directly to a planar surface, have a drawback in that some proteins will be denatured or cluster together after immobilization. Microsphere-based microarrays represent a more advanced strategy. The functional proteins are first attached to microspheres; these microspheres are then immobilized in arrays on a planar surface. In this dissertation, two approaches to assembling arrays of microspheres will be discussed. The hydrodynamic approach uses surface micromachining and Deep Reactive Ion Etching techniques to form an array of channels through a silicon wafer. By drawing fluid containing the microspheres through the channels they become trapped in the channels and thereby immobilized. In the magnetic approach, permalloy films are deposited on a silicon substrate and subsequently patterned to form magnetic attachment sites. An external magnetic field is then applied and the magnetic microspheres then assemble on these sites. Both devices are able to immobilize microspheres in an ordered array, as opposed to coarsely grouping them in array spots. The assembled arrays are robust in that

  3. Immobilisation and characterisation of biocatalytic co-factor recycling enzymes, glucose dehydrogenase and NADH oxidase, on aldehyde functional ReSyn™ polymer microspheres.

    PubMed

    Twala, Busisiwe V; Sewell, B Trevor; Jordaan, Justin

    2012-05-10

    The use of enzymes in industrial applications is limited by their instability, cost and difficulty in their recovery and re-use. Immobilisation is a technique which has been shown to alleviate these limitations in biocatalysis. Here we describe the immobilisation of two biocatalytically relevant co-factor recycling enzymes, glucose dehydrogenase (GDH) and NADH oxidase (NOD) on aldehyde functional ReSyn™ polymer microspheres with varying functional group densities. The successful immobilisation of the enzymes on this new high capacity microsphere technology resulted in the maintenance of activity of ∼40% for GDH and a maximum of 15.4% for NOD. The microsphere variant with highest functional group density of ∼3500 μmol g⁻¹ displayed the highest specific activity for the immobilisation of both enzymes at 33.22 U mg⁻¹ and 6.75 U mg⁻¹ for GDH and NOD with respective loading capacities of 51% (0.51 mg mg⁻¹) and 129% (1.29 mg mg⁻¹). The immobilised GDH further displayed improved activity in the acidic pH range. Both enzymes displayed improved pH and thermal stability with the most pronounced thermal stability for GDH displayed on ReSyn™ A during temperature incubation at 65 °C with a 13.59 fold increase, and NOD with a 2.25-fold improvement at 45 °C on the same microsphere variant. An important finding is the suitability of the microspheres for stabilisation of the multimeric protein GDH.

  4. Functional Magnetic Resonance Imaging Methods

    PubMed Central

    Chen, Jingyuan E.; Glover, Gary H.

    2015-01-01

    Since its inception in 1992, Functional Magnetic Resonance Imaging (fMRI) has become an indispensible tool for studying cognition in both the healthy and dysfunctional brain. FMRI monitors changes in the oxygenation of brain tissue resulting from altered metabolism consequent to a task-based evoked neural response or from spontaneous fluctuations in neural activity in the absence of conscious mentation (the “resting state”). Task-based studies have revealed neural correlates of a large number of important cognitive processes, while fMRI studies performed in the resting state have demonstrated brain-wide networks that result from brain regions with synchronized, apparently spontaneous activity. In this article, we review the methods used to acquire and analyze fMRI signals. PMID:26248581

  5. Magnetic Resonance Imaging-Based Radiation-Absorbed Dose Estimation of {sup 166}Ho Microspheres in Liver Radioembolization

    SciTech Connect

    Seevinck, Peter R.; Maat, Gerrit H. van de; Wit, Tim C. de; Vente, Maarten A.D.; Nijsen, Johannes F.W.; Bakker, Chris J.G.

    2012-07-01

    Purpose: To investigate the potential of magnetic resonance imaging (MRI) for accurate assessment of the three-dimensional {sup 166}Ho activity distribution to estimate radiation-absorbed dose distributions in {sup 166}Ho-loaded poly (L-lactic acid) microsphere ({sup 166}Ho-PLLA-MS) liver radioembolization. Methods and Materials: MRI, computed tomography (CT), and single photon emission CT (SPECT) experiments were conducted on an anthropomorphic gel phantom with tumor-simulating gel samples and on an excised human tumor-bearing liver, both containing known amounts of {sup 166}Ho-PLLA-MS. Three-dimensional radiation-absorbed dose distributions were estimated at the voxel level by convolving the {sup 166}Ho activity distribution, derived from quantitative MRI data, with a {sup 166}Ho dose point-kernel generated by MCNP (Monte Carlo N-Particle transport code) and from Medical Internal Radiation Dose Pamphlet 17. MRI-based radiation-absorbed dose distributions were qualitatively compared with CT and autoradiography images and quantitatively compared with SPECT-based dose distributions. Both MRI- and SPECT-based activity estimations were validated against dose calibrator measurements. Results: Evaluation on an anthropomorphic phantom showed that MRI enables accurate assessment of local {sup 166}Ho-PLLA-MS mass and activity distributions, as supported by a regression coefficient of 1.05 and a correlation coefficient of 0.99, relating local MRI-based mass and activity calculations to reference values obtained with a dose calibrator. Estimated MRI-based radiation-absorbed dose distributions of {sup 166}Ho-PLLA-MS in an ex vivo human liver visually showed high correspondence to SPECT-based radiation-absorbed dose distributions. Quantitative analysis revealed that the differences in local and total amounts of {sup 166}Ho-PLLA-MS estimated by MRI, SPECT, and the dose calibrator were within 10%. Excellent agreement was observed between MRI- and SPECT-based dose

  6. Fluorescent microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  7. Facile synthesis of novel magnetic silica nanoparticles functionalized with layer-by-layer detonation nanodiamonds for secretome study.

    PubMed

    Li, Hong; Wang, Yi; Zhang, Lei; Lu, Haojie; Zhou, Zhongjun; Wei, Liming; Yang, Pengyuan

    2015-12-07

    Novel magnetic silica nanoparticles functionalized with layer-by-layer detonation nanodiamonds (dNDs) were prepared by coating single submicron-size magnetite particles with silica and subsequently modified with dNDs. The resulting layer-by-layer dND functionalized magnetic silica microspheres (Fe3O4@SiO2@[dND]n) exhibit a well-defined magnetite-core-silica-shell structure and possess a high content of magnetite, which endow them with high dispersibility and excellent magnetic responsibility. Meanwhile, dNDs are known for their high affinity and biocompatibility towards peptides or proteins. Thus, a novel convenient, fast and efficient pretreatment approach of low-abundance peptides or proteins was successfully established with Fe3O4@SiO2@[dND]n microspheres. The signal intensity of low-abundance peptides was improved by at least two to three orders of magnitude in mass spectrometry analysis. The novel microsphere also showed good tolerance to salt. Even with a high concentration of salt, peptides or proteins could be isolated effectively from samples. Therefore, the convenient and efficient enrichment process of this novel layer-by-layer dND-functionalized microsphere makes it a promising candidate for isolation of protein in a large volume of culture supernatant for secretome analysis. In the application of Fe3O4@SiO2@[dND]n in the secretome of hepatoma cells, 1473 proteins were identified and covered a broad range of pI and molecular weight, including 377 low molecular weight proteins.

  8. Thiol-functionalized Fe3O4/SiO2 microspheres with superparamagnetism and their adsorption properties for Au(III) ion separation

    NASA Astrophysics Data System (ADS)

    Peng, Xiangqian; Zhang, Wei; Gai, Ligang; Jiang, Haihui; Tian, Yan

    2016-08-01

    Thiol-functionalized Fe3O4/SiO2 microspheres (Fe3O4/SiO2-SH) with high saturation magnetization (69.3 emu g-1), superparamagnetism, and good dispersibility have been prepared by an ethylene glycol reduction method in combination with a modified Stöber method. The as-prepared composite magnetic spheres are characterized with fourier transform infrared spectroscopy (FT-IR), zeta potential, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference magnetometer, and tested in separation of Au(III) ions from aqueous solutions. The data for Au(III) adsorption on Fe3O4/SiO2-SH are analyzed with the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models, and the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics models. The adsorption behaviors of Au(III) on Fe3O4/SiO2-SH follow the Langmuir isotherm model, and the adsorption process conforms to the pseudo-second-order kinetic model. The maximum adsorption capacity of Au(III) on Fe3O4/SiO2-SH is 43.7 mg g-1. Acetate anions play an important role yet Cu(II) ions have little interference in the adsorption of Au(III) on the adsorbent. A satisfactory recovery percentage of 89.5% is acquired by using an eluent with 1 M thiourea and 5% HCl, although thiols have a high affinity to Au(III) ions based on the hard-soft acid-base (HSAB) theory by Pearson.

  9. Preparation and Characterization of 45S5 Bioactive Glass-based Scaffolds Loaded with PHBV Microspheres with Daidzein Release Function.

    PubMed

    Macías-Andrés, Víctor I; Li, Wei; Aguilar-Reyes, Ena A; Ding, Yaping; Roether, Judith A; Harhaus, Leila; León-Patiño, Carlos A; Boccaccini, A R

    2017-02-27

    PHBV microsphere loaded 45S5 bioactive glass (BG) based scaffolds with drug releasing capability have been developed. PHBV microspheres with a mean particle size 4 ± 2 μm loaded with daidzein were obtained by oil-in-water single emulsion solvent evaporation method and applied to the surface of BG scaffolds by dip coating technique. The morphology, in vitro bioactivity in simulated body fluid (SBF), mechanical properties and drug release kinetics of microsphere loaded scaffolds were studied. The microspheres were shown to be homogeneously dispersed on the scaffold surfaces. It was confirmed that hydroxyapatite crystals homogeneously grew not only on the surface of the scaffold but also on the surface of the microspheres within 3 days of immersion in SBF. The daidzein release from the microsphere loaded scaffolds lasted almost 1 month and was determined to be diffusion controlled. The microsphere loaded BG scaffolds with daidzein releasing capability obtained in this study are a candidate for bone tissue engineering. This article is protected by copyright. All rights reserved.

  10. Hydrophilic core-shell microspheres: a suitable support for controlled attachment of proteins and biomedical diagnostics.

    PubMed

    Basinska, Teresa

    2005-12-15

    Functional hydrophilic microspheres (latex particles) have found various applications in life sciences and in medicine - particularly in latex diagnostic tests. This paper presents a comprehensive review of studies on latex particles with a hydrophilic interfacial layer composed of various hydrophilic polymers with reactive groups at the ends of macromolecules or at each monomeric unit along the chain. Typical examples of these hydrophilic polymers are poly(2-hydroxyethyl methyl methacrylate), poly(acrylic acid), poly(N,N-dimethylacrylamide), polysaccharides, poly(ethylene oxide) and polyglycidol. Hydrophilic microspheres with different morphologies (uniform or core-shell, see Figure) have been synthesized by emulsion and dispersion polymerizations. The chemical structure of polymers which constitute the interfacial layer of microspheres has been investigated using a variety of instrumental techniques (such as XPS, SSIMS and NMR) and analytical methods based on specific chemical reactions suitable for the determination of particular functional groups. Microspheres are exposed to contact with proteins in the majority of medical applications. This paper presents examples of studies on the attachment of these biomacromolecules to microspheres. The relation between the structure of the interfacial layer of microspheres and the ability of these particles for the covalent binding of proteins is discussed. Several examples of diagnostic tests, in which hydrophilic microspheres with adsorbed or covalently immobilized proteins were used as reagents, are presented. The paper also contains a short review of the application of magnetic hydrophilic particles for protein separation. Examples of hydrophilic latex particles used for hemoperfusion or heavy metal ion separation are presented. Hydrophilic microspheres with uniform or core-shell morphologies.

  11. Functional Magnetic Resonance Imaging and Pediatric Anxiety

    ERIC Educational Resources Information Center

    Pine, Daniel S.; Guyer, Amanda E.; Leibenluft, Ellen; Peterson, Bradley S.; Gerber, Andrew

    2008-01-01

    The use of functional magnetic resonance imaging in investigating pediatric anxiety disorders is studied. Functional magnetic resonance imaging can be utilized in demonstrating parallels between the neural architecture of difference in anxiety of humans and the neural architecture of attention-orienting behavior in nonhuman primates or rodents.…

  12. Functional Magnetic Resonance Imaging and Pediatric Anxiety

    ERIC Educational Resources Information Center

    Pine, Daniel S.; Guyer, Amanda E.; Leibenluft, Ellen; Peterson, Bradley S.; Gerber, Andrew

    2008-01-01

    The use of functional magnetic resonance imaging in investigating pediatric anxiety disorders is studied. Functional magnetic resonance imaging can be utilized in demonstrating parallels between the neural architecture of difference in anxiety of humans and the neural architecture of attention-orienting behavior in nonhuman primates or rodents.…

  13. Bisphosphonate release profiles from magnetite microspheres.

    PubMed

    Miyazaki, Toshiki; Inoue, Tatsuya; Shirosaki, Yuki; Kawashita, Masakazu; Matsubara, Takao; Matsumine, Akihiko

    2014-10-01

    Hyperthermia has been suggested as a novel, minimally invasive cancer treatment method. After implantation of magnetic nano- or microparticles around a tumour through blood vessels, irradiation with alternating magnetic fields facilitates the efficient in situ hyperthermia even for deep-seated tumours. On the basis of this idea, if the microspheres are capable of delivering drugs, they could be promising multifunctional biomaterials effective for chemotherapy as well as hyperthermia. In the present study, magnetite microspheres were prepared by aggregation of the iron oxide colloid in water-in-oil (W/O) emulsion. The release behaviour of alendronate, a typical bisphosphonate, from the microspheres was examined in vitro as a model of the bone tumour prevention and treatment system. The alendronate was successfully incorporated onto the porous magnetite microspheres in vacuum conditions. The drug-loaded microspheres maintained their original spherical shapes even after shaking in ultrapure water for 3 days, suggesting that they have sufficient mechanical integrity for clinical use. It was attributed to high aggregation capability of the magnetite nanoparticles through van der Waals and weak magnetic attractions. The microspheres showed slow release of the alendronate in vitro, resulting from tight covalent or ionic interaction between the magnetite and the alendronate. The release rate was diffusion-controlled type and well controlled by the alendronate concentration in drug incorporation to the microspheres.

  14. Production of monodisperse, polymeric microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Rhim, Won-Kyu (Inventor); Hyson, Michael T. (Inventor); Chang, Manchium (Inventor)

    1990-01-01

    Very small, individual polymeric microspheres with very precise size and a wide variation in monomer type and properties are produced by deploying a precisely formed liquid monomer droplet, suitably an acrylic compound such as hydroxyethyl methacrylate into a containerless environment. The droplet which assumes a spheroid shape is subjected to polymerizing radiation such as ultraviolet or gamma radiation as it travels through the environment. Polymeric microspheres having precise diameters varying no more than plus or minus 5 percent from an average size are recovered. Many types of fillers including magnetic fillers may be dispersed in the liquid droplet.

  15. Novel polystyrene microspheres functionalized by imidazolium and the electrocatalytic activity towards H2O2 of its Prussian blue composite

    NASA Astrophysics Data System (ADS)

    Mao, Hui; Song, Jinling; Zhang, Qian; Liu, Daliang; Gong, Naiqi; Li, Ying; Wu, Qiong; Verpoort, Francis; Song, Xi-Ming

    2013-05-01

    Copolymerization of styrene (St) and 1-vinyl-3-ethylimidazolium bromide (VEIB), novel poly(St-co-VEIB) microspheres were generated. Owing to the presence of imidazolium groups, such microspheres having an average diameter of 125 nm, behave electropositively when dispersed in aqueous solution. Furthermore, due to the presence of imidazolium groups, having a capacity of ion-exchange and weak reducibility on the surface of the PS microspheres, [Fe(CN)6]3- was absorbed on the surface of poly(St-co-VEIB) microspheres, and simultaneously, Fe3+ was reduced to Fe2+. Thus, in situ growth of Prussian blue (PB) nanoparticles could occur on the surface of poly(St-co-VEIB) microspheres without the addition of any other reducing agent. This methodology, utilizing the ion-exchange and weak reducibility properties of the imidazolium groups on the surface of micro-/nanostructures is a novel general method for assembling hierarchical nanostructured materials. Finally, the electrochemical property of the strawberry-like PS/PB composite microspheres was also investigated by applying a glassy carbon electrode. A good repeatability of the cyclic voltammetry responses, having a good linearity and sensitivity, for the electrocatalytic reduction of H2O2 was obtained.

  16. Adsorption of 1-butyl-3-methylimidazolium chloride ionic liquid by functional carbon microspheres from hydrothermal carbonization of cellulose.

    PubMed

    Qi, Xinhua; Li, Luyang; Tan, Tengfei; Chen, Wenting; Smith, Richard L

    2013-03-19

    Functional carbonaceous material (FCM) loaded with carboxylic groups was prepared by hydrothermal carbonization of cellulose in the presence of acrylic acid. The resulting FCM was used as adsorbent for recovery of a water-soluble ionic liquid, 1-butyl-3-methyl-imidazolium chloride ([BMIM][Cl]). The FCM consisted of microspheres (100-150 nm) and had a low surface area (ca. 20 m(2)/g), but exhibited adsorption capacity comparable to that of commercial activated carbon which can be attributed to the presence of high content of polar oxygenated groups (-OH, -C═O, -COOH) as revealed by spectral analyses. Sorption of [BMIM][Cl] onto FCM adsorbent could be well-described by pseudo-second-order kinetics. Thermodynamic and adsorption isothermal analyses revealed that the adsorption process was spontaneous, exothermic, and could be described by the Freundlich adsorption model. The FCM adsorbent could be regenerated effectively and recycled for at least three times without loss of adsorption capacity. The results of this work provide a facile method for production of functional carbonaceous materials from renewable resources that can be used for treatment of aqueous streams containing small concentrations of ionic liquid, [BMIM][Cl].

  17. Multifunctional Fe3O4@TiO2@Au magnetic microspheres as recyclable substrates for surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoqing; Zhu, Yihua; Yang, Xiaoling; Zhou, Ying; Yao, Yifan; Li, Chunzhong

    2014-05-01

    Herein, we demonstrate the design and fabrication of multifunctional triplex Fe3O4@TiO2@Au core-shell magnetic microspheres (MSs), which show excellent surface enhanced Raman scattering (SERS) activity with high reproducibility and stability. In addition, due to their excellent catalytic properties, the as-prepared Fe3O4@TiO2@Au magnetic MSs can clean themselves by photocatalytic degradation of target molecules adsorbed onto the substrate under irradiation with visible light, and can be re-used for several cycles with convenient magnetic separability. The influence of the size and distribution of Au nanoparticles (NPs) on the Fe3O4@TiO2 beads is investigated. The optimized samples employing Au NPs of 15 nm size and an areal density of about 2120 Au NPs on every MS show the best SERS activity and recyclable performance. The experimental results show that these magnetic MSs indicate a new route in eliminating the `single-use' problem of traditional SERS substrates and exhibit their applicability as analytical tools for the detection of different molecular species.

  18. Ionic liquid-modified magnetic polymeric microspheres as dispersive solid phase extraction adsorbent: a separation strategy applied to the screening of sulfamonomethoxine and sulfachloropyrazine from urine.

    PubMed

    Yan, Hongyuan; Gao, Mengmeng; Yang, Chen; Qiu, Mande

    2014-04-01

    Ionic liquid-modified magnetic polymeric microspheres (ILMPM) were prepared based on Fe3O4 magnetic nanoparticles (MNPs) and ionic liquids (ILs) incorporated into a polymer. The composites were characterized using scanning electron microscopy, Fourier transform infrared analysis, thermogravimetric analysis, X-ray diffraction, and vibrating magnetometer, which indicated that ILMPM had a regularly spherical shape and strong magnetic property. The obtained ILMPM were successfully applied as a special adsorbent of magnetic dispersive solid phase extraction (MDSPE) for the rapid extraction and isolation of sulfamonomethoxine sodium and sulfachloropyrazine sodium in urine. The factors that affected extraction efficiency, such as adsorption conditions, desorption conditions, washing and elution solvents, and pH of the sample solution, were optimized. Under the optimum condition, good linearity in the range of 0.005-2.0 μg g(-1) (r ≥ 0.9996) was obtained for the two sulfonamides (SAs); the average recoveries at three spiked levels ranged from 86.9 to 102.1 %, with relative standard deviations of ≤4.3 %. The presented ILMPM-MDSPE method combined the advantages of ILs, MNPs, and MDSPE and therefore could be potentially applied for rapid screening of SAs in urine.

  19. Fully automatic input function determination program for simple noninvasive (123)I-IMP microsphere cerebral blood flow quantification method.

    PubMed

    Yamashita, Kosuke; Uchiyama, Yoshikazu; Ofuji, Asato; Mimura, Hiroaki; Okumiya, Shintaro; Takaki, Akihiro; Sone, Teruki; Ito, Shigeki

    2016-09-01

    We recently developed a simple noninvasive (123)I-IMP microsphere (SIMS) method using chest dynamic planar images and brain single photon emission computed tomography. The SIMS method is an automatic analysis method, except for the process of setting the region of interest (ROI) of the input function. If a fully automatic ROI setting algorithm can be developed to determine the input function for the SIMS method, repeatability and reproducibility of the analysis of regional cerebral blood flow (rCBF) of the SIMS method can be guaranteed. The purpose of this study is to develop a fully automatic input function determination program for the SIMS method and to confirm the clinical usefulness of this program. The automatic input function determination program consists of two ROI setting programs for the PA and lung regions, and it is developed using the image phase analysis of a chest RI angiogram. To confirm the clinical usefulness of this program, the rCBF in 34 patients measured using the automatic method were compared with the values obtained through the manual setting method. Input functions by the automatic and manual methods were approximately equal. A good correlation was observed between the rCBF values obtained by the automatic method and those obtained by the manual setting method (r=0.96, p<0.01). Further, the total time taken for the automatic SIMS analysis is 1-2min as compared to 20-30min for the current analysis, and therefore, this technique contributes to the improvement of the throughput of nuclear medical examinations. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  20. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, R.M.

    A method and apparatus is disclosed for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  1. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, Russell M.

    1980-01-01

    A method and apparatus for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated to relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  2. Proteins combination on PHBV microsphere scaffold to regulate Hep3B cells activity and functionality: a model of liver tissue engineering system.

    PubMed

    Zhu, Xin Hao; Gan, Seng Keat; Wang, Chi-Hwa; Tong, Yen Wah

    2007-12-01

    The synergistic effects of extracellular matrix (ECM) protein combinations on Hep3B cell proliferation and functions are studied herein. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microspheres were covalently conjugated with three types of proteins, collagen (type I), laminin, and fibronectin, using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide cross linkers. Successful conjugations of protein molecules were verified by the presence of nitrogen peaks in X-ray photoelectron spectroscopy. The densities of grafted proteins were quantified using Micro-BCA kit. A human hepatoma cell line, Hep3B, was then cultured in vitro on the ECM proteins-modified microspheres for 2 weeks. Cell proliferation was estimated using MTT method, and two hepatic functions, albumin secretion and P-450 activity, were evaluated using ELISA and EROD assays, respectively. The results indicated that combination of the three ECM proteins on microsphere surfaces has a significant effect on the proliferation of Hep3B cells, thus better mimicking the in vivo environment for liver tissue engineering.

  3. Magnetic fields and density functional theory

    SciTech Connect

    Salsbury Jr., Freddie

    1999-02-01

    A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.

  4. Magnetic Targeting Enhances Engraftment and Functional Benefit of Iron-Labeled Cardiosphere-Derived Cells in Myocardial Infarction

    PubMed Central

    Cheng, Ke; Li, Tao-Sheng; Malliaras, Konstantinos; Davis, Darryl; Zhang, Yiqiang; Marbán, Eduardo

    2010-01-01

    Rationale The success of cardiac stem cell therapies is limited by low cell retention, due at least in part to washout via coronary veins. Objective We sought to counter the efflux of transplanted cells by rendering them magnetically-responsive and imposing an external magnetic field on the heart during and immediately after injection. Methods and Results Cardiosphere-derived cells (CDCs) were labeled with superparamagnetic microspheres (SPMs). In vitro studies revealed that cell viability and function were minimally affected by SPM labeling. SPM-labeled rat CDCs were injected intramyocardially, with and without a superimposed magnet. With magnetic targeting, cells were visibly attracted towards the magnet and accumulated around the ischemic zone. In contrast, the majority of non-targeted cells washed out immediately after injection. Fluorescence imaging revealed more retention of transplanted cells in the heart, and less migration into other organs, in the magnetically-targeted group. Quantitative PCR confirmed that magnetic targeting enhanced cell retention (at 24 hours) and engraftment (at 3 weeks) in the recipient hearts by ∼3-fold compared to non-targeted cells. Morphometric analysis revealed maximal attenuation of LV remodeling, and echocardiography showed the greatest functional improvement, in the magnetic targeting group. Histologically, more engrafted cells were evident with magnetic targeting, but there was no incremental inflammation. Conclusion Magnetic targeting enhances cell retention, engraftment and functional benefit. This novel method to improve cell therapy outcomes offers the potential for rapid translation into clinical applications. PMID:20378859

  5. Preparation and characterization of monodisperse core-shell Fe3O4@SiO2 microspheres and its application for magnetic separation of nucleic acids from E. coli BL21.

    PubMed

    Ma, Chao; Li, Chuanyan; He, Nongyue; Wang, Fang; Ma, Ningning; Zhang, Liming; Lu, Zhuoxuan; Ali, Zeeshan; Xi, Zhijiang; Li, Xiaolong; Liang, Gaofeng; Liu, Hongna; Deng, Yan; Xu, Lijian; Wang, Zhifei

    2012-12-01

    In this article, we present an easy route to prepare monodisperse core-shell Fe3O4@SiO2 microspheres with uniform size and shape. Their structures and properties were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), and vibrating sample magnetometer (VSM), respectively. The results showed that spherical Fe3O4 microspheres with well dispersion have a rough surface and an average diameter (about 500 nm). After the modification with silica, the particles have a well-defined core-shell structure and a much smoother surface and larger particle diameter (about 600 nm). Furthermore, VSM measurements indicated that the as-prepared Fe3O4 and Fe3O4@SiO2 microspheres were superparamagnetic at room temperature and the saturation magnetization (M(s)) were 58.110 emu/g and 33.479 emu/g, respectively. And then, the prepared monodisperse core-shell Fe3O4@SiO2 microspheres were subsequently applied to separate nucleic acids from the bacteria (E. coli BL21) and verified the great application prospects for bioseparation technology of the biomoleculars.

  6. Acrolein Microspheres Are Bonded To Large-Area Substrates

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan; Yen, Richard C. K.

    1988-01-01

    Reactive cross-linked microspheres produced under influence of ionizing radiation in aqueous solutions of unsaturated aldehydes, such as acrolein, with sodium dodecyl sulfate. Diameters of spheres depend on concentrations of ingredients. If polystyrene, polymethylmethacrylate, or polypropylene object immersed in solution during irradiation, microspheres become attached to surface. Resulting modified surface has grainy coating with reactivity similar to free microspheres. Aldehyde-substituted-functional microspheres react under mild conditions with number of organic reagents and with most proteins. Microsphere-coated macrospheres or films used to immobilize high concentrations of proteins, enzymes, hormones, viruses, cells, and large number of organic compounds. Applications include separation techniques, clinical diagnostic tests, catalytic processes, and battery separators.

  7. Acrolein Microspheres Are Bonded To Large-Area Substrates

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan; Yen, Richard C. K.

    1988-01-01

    Reactive cross-linked microspheres produced under influence of ionizing radiation in aqueous solutions of unsaturated aldehydes, such as acrolein, with sodium dodecyl sulfate. Diameters of spheres depend on concentrations of ingredients. If polystyrene, polymethylmethacrylate, or polypropylene object immersed in solution during irradiation, microspheres become attached to surface. Resulting modified surface has grainy coating with reactivity similar to free microspheres. Aldehyde-substituted-functional microspheres react under mild conditions with number of organic reagents and with most proteins. Microsphere-coated macrospheres or films used to immobilize high concentrations of proteins, enzymes, hormones, viruses, cells, and large number of organic compounds. Applications include separation techniques, clinical diagnostic tests, catalytic processes, and battery separators.

  8. Characteristics of equilibrium, kinetics studies for adsorption of Hg(II), Cu(II), and Ni(II) ions by thiourea-modified magnetic chitosan microspheres.

    PubMed

    Zhou, Limin; Wang, Yiping; Liu, Zhirong; Huang, Qunwu

    2009-01-30

    Magnetic chitosan microspheres were prepared and chemically modified with thiourea (TMCS) for adsorption of metal ions. TMCS obtained were investigated by means of X-ray diffraction (XRD), IR, magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of TMCS toward Hg(2+), Cu(2+), and Ni(2+) ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetics was evaluated utilizing the pseudo-first-order, pseudo-second-order, and the intra-particle diffusion models. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 625.2, 66.7, and 15.3mg/g for Hg(2+), Cu(2+), and Ni(2+) ions, respectively. TMCS displayed higher adsorption capacity for Hg(2+) in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded TMCS with were regenerated with an efficiency of greater than 88% using 0.01-0.1M ethylendiamine tetraacetic acid (EDTA).

  9. Preparation of chitosan/poly(acrylic acid) magnetic composite microspheres and applications in the removal of copper(II) ions from aqueous solutions.

    PubMed

    Yan, Han; Yang, Lingyun; Yang, Zhen; Yang, Hu; Li, Aimin; Cheng, Rongshi

    2012-08-30

    In this current work, the magnetic composite microspheres (MCM), consisting of Fe(3)O(4) nanoparticles and poly(acrylic acid) (PAA) blended chitosan (CS), were prepared successfully by a simple method, co-precipitation of the compounds in alkaline solution. SEM, FTIR and TG techniques have been applied to investigate the structures of the MCM materials. The vibrating-sample magnetometer (VSM) measurement illustrated a paramagnetic property as well as a fast magnetic response, which indicated the significant separability of the MCM in the aqueous suspensions. Then, the MCM materials were employed as absorbents for removal of copper(II) (Cu(II)) ions from aqueous solutions. The fundamental adsorption behaviors of MCM were studied also. Experimental results revealed that the CS/PAA-MCM had greater adsorption capacity than CS-MCM, and PAA played an important role for the adsorption of Cu(II) ions. Moreover, the adsorption isotherms were all well described by the Langmuir model, while the adsorption kinetics followed the pseudo-second order equation. Furthermore, the adsorbent could be easily regenerated at lower pH and reused almost without any loss of adsorption capacity. On the contrary, the Cu(II) ions loaded CS-MCM and CS/PAA-MCM were stable enough at pH higher than 4.0, and both exhibited efficient phosphate removal with maximal uptakes around 63.0 and 108.0 mg Pg(-1), respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. In situ assembly of monodisperse, multifunctional silica microspheres embedded with magnetic and fluorescent nanoparticles and their application in adsorption of methylene blue.

    PubMed

    Shi, Jianhui; Ren, Xiaozhen; Tong, Lizhu; Chen, Xiaodong; Yang, Xuwei; Yang, Hua

    2013-11-14

    Many efforts have been devoted towards the fabrication of multifunctional (mesoporous, magnetic and fluorescent) nanocomposites due to their growing applications as adsorbents, catalysts, and biomedical application, etc. Novel, flower-structured multifunctional Fe3O4/YVO4:Eu(3+)@SiO2 microspheres were successfully synthesized through a simple self-assembled process. The as-obtained products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, photoluminescence (PL) spectroscopy and using a vibrating sample magnetometer (VSM). The results reveal that the novel composites exhibit typical mesoporous structure, narrow size distribution, good monodispersity, excellent luminescent properties and superparamagnetic features. The effects of magnetic field on the luminescent intensity of multifunctional composites have been discussed in our manuscript. Furthermore, the adsorption experiments indicate that the resulting multifunctional composites are powerful adsorbents for the removal of methylene blue from water with a maximum adsorption efficiency of 98%. It is envisioned that multifunctional composites with high surface area are of particular interest for adsorption of pollutants, separation, and water purification.

  11. Functional Nanomaterials Useful for Magnetic Refrigeration Systems

    NASA Astrophysics Data System (ADS)

    Aslani, Amir

    Magnetic refrigeration is an emerging energy efficient and environmentally friendly refrigeration technology. The principle of magnetic refrigeration is based on the effect of varying a magnetic field on the temperature change of a magnetocaloric material (refrigerant). By applying a magnetic field, the magnetic moments of a magnetic material tend to align parallel to it, and the thermal energy released in this process heats the material. Reversibly, the magnetic moments become randomly oriented when the magnetic field is removed, and the material cools down. The heating and the cooling of a refrigerant in response to a changing magnetic field is similar to the heating and the cooling of a gaseous medium in response to an adiabatic compression and expansion in a conventional refrigeration system. One requirement to make a practical magnetic refrigerator is to have a large temperature change per unit of applied magnetic field, with sufficiently wide operating temperature. So far, no commercially viable magnetic refrigerator has been built primarily due to the low temperature change of bulk refrigerants, the added burden of hysteresis, and the system's low cooling capacity. The purpose of this dissertation is to explore magnetic refrigeration system. First, the Active Magnetic Regenerator (AMR) system built by Shir et al at the GWU's Institute for Magnetics Research (IMR) is optimized by tuning the heat transfer medium parameters and system's operating conditions. Next, by reviewing literature and works done so far on refrigerants, a number of materials that may be suitable to be used in magnetic refrigeration technology were identified. Theoretical work by Bennett et al showed an enhancement in magnetocaloric effect of magnetic nanoparticles. Research was performed on functional magnetic nanoparticles and their use in magnetic refrigeration technology. Different aspects such as the size, shape, chemical composition, structure and interaction of the nanoparticle with

  12. Role of coherence in microsphere-assisted nanoscopy

    NASA Astrophysics Data System (ADS)

    Perrin, Stephane; Lecler, Sylvain; Leong-Hoi, Audrey; Montgomery, Paul C.

    2017-06-01

    The loss of the information, due to the diffraction and the evanescent waves, limits the resolving power of classical optical microscopy. In air, the lateral resolution of an optical microscope can approximated at half of the wavelength using a low-coherence illumination. Recently, several methods have been developed in order to overcome this limitation and, in 2011, a new far-field and full-field imaging technique was proposed where a sub-diffraction-limit resolution has been achieved using a transparent microsphere. In this article, the phenomenon of super-resolution using microsphere-assisted microscopy is analysed through rigorous electro-magnetic simulations. The performances of the imaging technique are estimated as function of optical and geometrical parameters. Furthermore, the role of coherence is introduced through the temporal coherence of the light source and the phase response of the object.

  13. Tutte polynomial in functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    García-Castillón, Marlly V.

    2015-09-01

    Methods of graph theory are applied to the processing of functional magnetic resonance images. Specifically the Tutte polynomial is used to analyze such kind of images. Functional Magnetic Resonance Imaging provide us connectivity networks in the brain which are represented by graphs and the Tutte polynomial will be applied. The problem of computing the Tutte polynomial for a given graph is #P-hard even for planar graphs. For a practical application the maple packages "GraphTheory" and "SpecialGraphs" will be used. We will consider certain diagram which is depicting functional connectivity, specifically between frontal and posterior areas, in autism during an inferential text comprehension task. The Tutte polynomial for the resulting neural networks will be computed and some numerical invariants for such network will be obtained. Our results show that the Tutte polynomial is a powerful tool to analyze and characterize the networks obtained from functional magnetic resonance imaging.

  14. Functionalized magnetic nanoparticle analyte sensor

    DOEpatents

    Yantasee, Wassana; Warner, Maryin G; Warner, Cynthia L; Addleman, Raymond S; Fryxell, Glen E; Timchalk, Charles; Toloczko, Mychailo B

    2014-03-25

    A method and system for simply and efficiently determining quantities of a preselected material in a particular solution by the placement of at least one superparamagnetic nanoparticle having a specified functionalized organic material connected thereto into a particular sample solution, wherein preselected analytes attach to the functionalized organic groups, these superparamagnetic nanoparticles are then collected at a collection site and analyzed for the presence of a particular analyte.

  15. Dissipation function in a magnetic field (Review)

    NASA Astrophysics Data System (ADS)

    Gurevich, V. L.

    2015-07-01

    The dissipation function is introduced to describe the behavior of the system of harmonic oscillations interacting with the environment (thermostat). This is a quadratic function of generalized velocities, which determines the rate of dissipation of the mechanical energy in the system. It was assumed earlier (Landau, Lifshitz) that the dissipation function can be introduced only in the absence of magnetic field. In the present review based on the author's studies, it has been shown how the dissipation function can be introduced in the presence of a magnetic field B. In a magnetic field, both dissipative and nondissipative responses arise as a response to perturbation and are expressed in terms of kinetic coefficients. The matrix of nondissipative coefficients can be obtained to determine an additional term formally including it into the equations of motion, which still satisfy the energy conservation law. Then, the dissipative part of the matrix can be considered in exactly the same way as without magnetic field, i.e., it defines the dissipation loss. As examples, the propagation and absorption of ultrasound in a metal or a semiconductor in a magnetic field have been considered using two methods: (i) the method based on the phenomenological theory using the equations of the theory of elasticity and (ii) the method based on the microscopic approach by analyzing and solving the kinetic equation. Both examples are used to illustrate the approach with the dissipation function.

  16. Highly Efficient visible-light-induced photoactivity of magnetically retrievable Fe3O4@SiO2@Bi2WO6@g-C3N4 hierarchical microspheres for the degradation of organic pollutant and production of hydrogen

    NASA Astrophysics Data System (ADS)

    Lu, Dingze; Wang, Hongmei; Shen, Qingqing; Kondamareddy, Kiran Kumar; Neena D

    2017-07-01

    The new multifunctional composite Fe3O4@SiO2@Bi2WO6@g-C3N4 (FSBG) hierarchical microspheres with Bi2WO6/g-C3N4 heterostructure as an outer shell and Fe3O4@SiO2 as a magnetic core have been synthesized and characterized for photocatalytic applications. An efficient and adoptable approach of synthesizing magnetic Bi2WO6/g-C3N4 hierarchical microspheres of grape-like morphology is realized. The as-synthesized structures exhibit highly efficient visible-light absorption and separation efficiency of photo-induced charge. The visible-light-induced photocatalytic activity of g-C3N4, Fe3O4@SiO2@Bi2WO6, and FSBG is evaluated by investigating the photodegradation of Rhodamine B (RhB) and hydrogen (H2) out of water. The comparative study reveals that the FSBG microspheres exhibit an optimum visible-light-induced photocatalytic activity in degrading Rhodamin B (RhB), which is 3.06 and 1.92 times to that of g-C3N4 and Fe3O4@SiO2@Bi2WO6 systems respectively and 3.89 and 2.31 times in the production of hydrogen (H2) out of water, respectively. The FSBG composite microspheres also exhibit good magnetic recoverability. An alternate mechanism for the enhanced visible-light photocatalytic activity is given in the present manuscript.

  17. microsphere assemblies

    NASA Astrophysics Data System (ADS)

    Peña-Flores, Jesús I.; Palomec-Garfias, Abraham F.; Márquez-Beltrán, César; Sánchez-Mora, Enrique; Gómez-Barojas, Estela; Pérez-Rodríguez, Felipe

    2014-09-01

    The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe+3 ion concentration increases.

  18. Effect of immobilized amine density on cadmium(II) adsorption capacities for ethanediamine-modified magnetic poly-(glycidyl methacrylate) microspheres

    NASA Astrophysics Data System (ADS)

    Dong, Tingting; Yang, Liangrong; Pan, Feng; Xing, Huifang; Wang, Li; Yu, Jiemiao; Qu, Hongnan; Rong, Meng; Liu, Huizhou

    2017-04-01

    A series of ethanediamine (EDA) - modified magnetic poly-(glycidyl methacrylate) (m-PGMA-EDA)microspheres with different amine density were synthesized and their cadmium saturation adsorption capacities were examined. The results showed that the cadmium saturation adsorption capacity increased with the immobilized amine density. However, they did not show strong positive linear correlation in the whole range of amine density examined. The molar ratio of amine groups to the adsorbed cadmium decreased with the increase of amine density and eventually reached a minimum value about 4. It suggested that low immobilized amine density led to low coordination efficiency of the amine. It is hypothesized that the immobilized amine groups needed to be physically close enough to form stable amine-metal complex. When the amine density reached to a critical value 1.25 m mol m-2, stable amine-cadmium complex (4:1 N/Cd) was proposed to form. To illustrate the coordination mechanism (structure and number) of amine and Cd, FT-IR spectra of m-PGMA-EDA and m-PGMA-EDA-Cd , and X-ray photoelectron spectroscopy (XPS) of PGMA-EDA and PGMA-EDA-Cd were examined and analyzed.

  19. Constrained density functional for noncollinear magnetism

    NASA Astrophysics Data System (ADS)

    Ma, Pui-Wai; Dudarev, S. L.

    2015-02-01

    Energies of arbitrary small- and large-angle noncollinear excited magnetic configurations are computed using a highly accurate constrained density functional theory approach. Numerical convergence and accuracy are controlled by the choice of Lagrange multipliers λI entering the constraining conditions. The penalty part Ep of the constrained energy functional at its minimum is shown to be inversely proportional to λI, enabling a simple, robust, and accurate iterative procedure to be followed to find a convergent solution. The method is implemented as a part of ab initio vasp package, and applied to the investigation of noncollinear B2-like and <001 > double-layer antiferromagnetic configurations of bcc iron, Fe2 dimer, and amorphous iron. Forces acting on atoms depend on the orientations of magnetic moments, and the proposed approach enables constrained self-consistent noncollinear magnetic and structural relaxation of large atomic systems to be carried out.

  20. Core-shell structured carbonyl iron microspheres prepared via dual-step functionality coatings and their magnetorheological response.

    PubMed

    Fang, Fei Fei; Liu, Ying Dan; Choi, Hyoung Jin; Seo, Yongsok

    2011-09-01

    The dispersion stability of soft magnetic carbonyl iron (CI)-based magnetorheological (MR) fluids was improved by applying a unique functional coating composed of a conducting polyaniline layer and a multiwalled carbon nanotube nest to the surfaces of the CI particles via conventional dispersion polymerization, followed by facile solvent casting. The coating morphology and thickness were analyzed by SEM and TEM imaging. Chemical composition of the polyaniline layer was detected by Raman spectroscope, which also confirmed the coating performance successfully. The influence of the functional coating on the magnetic properties was investigated by measuring the MR performance and sedimentation properties using a vibrating sample magnetometer, rotational rheometer, and Turbiscan apparatus. Improved dispersion characteristics of the MR fluid were observed.

  1. Microspheres and nanoparticles from ultrasound

    NASA Astrophysics Data System (ADS)

    Suh, Won Hyuk

    Improved preparations of various examples of monodispersed, porous, hollow, and core-shell metal and semiconductor nanoparticles or nanowires have been developed. Now titania microspheres and nanoparticles and silica microspheres can be synthesized using an inexpensive high frequency (1.7 MHz) ultrasonic generator (household humidifier; ultrasonic spray pyrolysis; USP). Morphology and pore size of titania microspheres were controlled by the silica to Ti(IV) ratio and silica particle size. Fine tuning the precursor ratio affords sub-50 nm titania nanoparticles as well. In terms of silica microspheres, morphology was controlled by the silica to organic monomer ratio. In liquids irradiated with high intensity ultrasound (20 kHz; HIUS), acoustic cavitation produces high energy chemistry through intense local heating inside the gas phase of collapsing bubbles in the liquid. HIUS and USP confine the chemical reactions to isolated sub-micron reaction zones, but sonochemistry does so in a heated gas phase within a liquid, while USP uses a hot liquid droplet carried by a gas flow. Thus, USP can be viewed as a method of phase-separated synthesis using submicron-sized droplets as isolated chemical reactors for nanomaterial synthesis. While USP has been used to create both titania and silica spheres separately, there are no prior reports of titania-silica composites. Such nanocomposites of metal oxides have been produced, and by further manipulation, various porous structures with fascinating morphologies were generated. Briefly, a precursor solution was nebulized using a commercially available household ultrasonic humidifier (1.7 MHz ultrasound generator), and the resulting mist was carried in a gas stream of air through a quartz glass tube in a hot furnace. After exiting the hot zone, these microspheres are porous or hollow and in certain cases magnetically responsive. In the case of titania microspheres, they are rapidly taken up into the cytoplasm of mammalian cells and

  2. Magnetic microsphere-confined graphene for the extraction of polycyclic aromatic hydrocarbons from environmental water samples coupled with high performance liquid chromatography-fluorescence analysis.

    PubMed

    Wang, Weina; Ma, Ruiyang; Wu, Qiuhua; Wang, Chun; Wang, Zhi

    2013-06-07

    In this paper, a magnetic microsphere-confined graphene adsorbent (Fe3O4@SiO2-G) was fabricated and used for the extraction of five polycyclic aromatic hydrocarbons (fluorene, anthracene, phenanthrene, fluoranthene and pyrene) from environmental water samples prior to high performance liquid chromatography with fluorescence detection. The Fe3O4@SiO2-G was characterized by various instrumental methods. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the pH and ionic strength of sample solution, the extraction time and the desorption conditions, were investigated. Due to the high surface area and excellent adsorption capacity of the Fe3O4@SiO2-G, satisfactory extraction can be achieved with only 15mg of the adsorbent per 250mL solution and 5min extraction. Under the optimum conditions, a linear response was observed in the concentration range of 5-1500ngL(-1) for fluorene, 2.5-1500ngL(-1) for anthracene and 15-1500ngL(-1) for phenanthrene, fluoranthene and pyrene, with the correlation coefficients (r) ranging from 0.9897 to 0.9961. The limits of detection (S/N=3) of the method were between 0.5 and 5.0ngL(-1). The relative standard deviations (RSDs) were less than 5.6%. The recoveries of the method were in the range between 83.2% and 108.2%. The results indicated that this graphene-based magnetic nanocomposite had a great adsorptive ability toward the five polycyclic aromatic hydrocarbons from environmental water samples.

  3. Mechanistic analysis of triamcinolone acetonide release from PLGA microspheres as a function of varying in vitro release conditions.

    PubMed

    Doty, Amy C; Zhang, Ying; Weinstein, David G; Wang, Yan; Choi, Stephanie; Qu, Wen; Mittal, Sachin; Schwendeman, Steven P

    2017-04-01

    In vitro tests for controlled release PLGA microspheres in their current state often do not accurately predict in vivo performance of these products during formulation development. Here, we introduce a new mechanistic and multi-phase approach to more clearly understand in vitro-in vivo relationships, and describe the first "in vitro phase" with the model drug, triamcinolone acetonide (Tr-A). Two microsphere formulations encapsulating Tr-A were prepared from PLGAs of different molecular weights and end-capping (18kDa acid-capped and 54kDa ester-capped). In vitro release kinetics and the evidence for controlling mechanisms (i.e., erosion, diffusion, and water-mediated processes) were studied in four release media: PBST pH 7.4 (standard condition), PBST pH 6.5, PBS+1.0% triethyl citrate (TC), and HBST pH 7.4. The release mechanism in PBST was primarily polymer erosion-controlled as indicated by the similarity of release and mass loss kinetics. Release from the low MW PLGA was accelerated at low pH due to increased rate of hydrolysis and in the presence of the plasticizer TC due to slightly increased hydrolysis and much higher diffusion in the polymer matrix. TC also increased release from the high MW PLGA due to increased hydrolysis, erosion, and diffusion. This work demonstrates how in vitro conditions can be manipulated to change not only rates of drug release from PLGA microspheres but also the mechanism(s) by which release occurs. Follow-on studies in the next phases of this approach will utilize these results to compare the mechanistic data of the Tr-A/PLGA microsphere formulations developed here after recovery of microspheres in vivo. This new approach based on measuring mechanistic indicators of release in vitro and in vivo has the potential to design better, more predictive in vitro release tests for these formulations and potentially lead to mechanism-based in vitro-in vivo correlations. Copyright © 2016. Published by Elsevier B.V.

  4. Polyacrolein microspheres as a new tool in cell biology.

    PubMed

    Margel, S; Beitler, U; Ofarim, M

    1982-08-01

    Polyacrolein (PA) microspheres in sizes ranging from 0.04 micron to 40 microns were synthesized. Magnetic and fluorescent PA microspheres were formed by carrying out the polymerization process in the presence of appropriate ferrofluidic or fluorochromic compounds, respectively. The microspheres carry reactive aldehyde groups, through which various ligands, containing primary amino groups, were covalently bound at physiological pH values. The potential use of these microspheres was demonstrated by the specific labelling of fresh human red blood cells (RBC) and by the separation of human RBC from turkey RBC by means of a magnetic field. PA microspheres were also bound covalently to the anti-allergic drug disodium chromoglycate (DSCG) and the conjugate was used for the labelling of rat basophilic leukaemia cells.

  5. Magnetic spectroscopy and microscopy of functional materials

    SciTech Connect

    Jenkins, Catherine Ann

    2011-05-01

    Heusler intermetallics Mn2Y Ga and X2MnGa (X; Y =Fe, Co, Ni) undergo tetragonal magnetostructural transitions that can result in half metallicity, magnetic shape memory, or the magnetocaloric effect. Understanding the magnetism and magnetic behavior in functional materials is often the most direct route to being able to optimize current materials for todays applications and to design novel ones for tomorrow. Synchrotron soft x-ray magnetic spectromicroscopy techniques are well suited to explore the the competing effects from the magnetization and the lattice parameters in these materials as they provide detailed element-, valence-, and site-specifc information on the coupling of crystallographic ordering and electronic structure as well as external parameters like temperature and pressure on the bonding and exchange. Fundamental work preparing the model systems of spintronic, multiferroic, and energy-related compositions is presented for context. The methodology of synchrotron spectroscopy is presented and applied to not only magnetic characterization but also of developing a systematic screening method for future examples of materials exhibiting any of the above effects. The chapter progression is as follows: an introduction to the concepts and materials under consideration (Chapter 1); an overview of sample preparation techniques and results, and the kinds of characterization methods employed (Chapter 2); spectro- and microscopic explorations of X2MnGa/Ge (Chapter 3); spectroscopic investigations of the composition series Mn2Y Ga to the logical Mn3Ga endpoint (Chapter 4); and a summary and overview of upcoming work (Chapter 5). Appendices include the results of a Think Tank for the Graduate School of Excellence MAINZ (Appendix A) and details of an imaging project now in progress on magnetic reversal and domain wall observation in the classical Heusler material Co2FeSi (Appendix B).

  6. Reversible switching between hydrophilic and hydrophobic superparamagnetic iron oxide microspheres via one-step supramolecular dynamic dendronization: exploration of dynamic wettability.

    PubMed

    Leung, Ken Cham-Fai; Xuan, Shouhu; Lo, Chui-Man

    2009-09-01

    We describe the use of hydrophobic poly(aryl ether) dendrons to peripherally functionalize hydrophilic amine-containing superparamagnetic iron oxide microspheres (SPIO-NH2) in one step via imine formation. The reversible formation of imine bonds in the absence/presence of water renders dynamic control of the hydrophilicity and hydrophobicity of the microspheres (SPIO-Gn). The dynamic nature of the imine-containing dendronized microspheres (SPIO-Gn) can be "fixed" by locking the reversible 2,6-diiminopyridyl moieties with metal cations (Zn2+, Co2+, and Ni2+) to afford kinetically stable dendronized microspheres (SPIO-Gn-M). Isolation of these microspheres is facilitated by convenient magnetic separation by an externally applied magnetic field. Characterization of these novel organic-inorganic hybrid microspheres has been performed by various techniques using UV/visible absorption and Fourier transform infrared spectroscopies, transmission electron microscopy, thermogravimetric analysis, and a vibrating sample magnetometer. We have demonstrated the stability and reversible switching of hydrophilicity/hydrophobicity by contact-angle measurements. In particular, the hydrophilic SPIO-NH2 microspheres demonstrated a contact angle of 42 +/- 2 degrees when a drop of water was added to a SPIO-NH2-coated mica surface. On the other hand, the hydrophobic SPIO-Gn-M dendronized microspheres demonstrated a contact angle of 85 +/- 2 degrees , an observation that involves an increase of the contact angle of over 40 degrees . Furthermore, when a drop of water was placed on a dynamic SPIO-Gn-coated mica surface, the contact angle of the water droplet decreased in time. Comparatively, the rate of decrease of the contact angle is H2O > 1% Co(OAc)2/H2O > N,N'-dimethylformamide/H2O (1:1).

  7. Multimodal Imaging of Nanocomposite Microspheres for Transcatheter Intra-Arterial Drug Delivery to Liver Tumors

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Hyun; Li, Weiguo; Chen, Jeane; Zhang, Zhuoli; Green, Richard M.; Huang, Sui; Larson, Andrew C.

    2016-07-01

    A modern multi-functional drug carrier is critically needed to improve the efficacy of image-guided catheter-directed approaches for the treatment of hepatic malignancies. For this purpose, a nanocomposite microsphere platform was developed for selective intra-arterial transcatheter drug delivery to liver tumors. In our study, continuous microfluidic methods were used to fabricate drug-loaded multimodal MRI/CT visible microspheres that included both gold nanorods and magnetic clusters. The resulting hydrophilic, deformable, and non-aggregated microspheres were mono-disperse and roughly 25 um in size. Sustained drug release and strong MRI T2 and CT contrast effects were achieved with the embedded magnetic nano-clusters and radiopaque gold nanorods. The microspheres were successfully infused through catheters selectively placed within the hepatic artery in rodent models and subsequent distribution in the targeted liver tissues and hepatic tumors confirmed with MRI and CT imaging. These multimodal nanocomposite drug carriers should be ideal for selective intra-arterial catheter-directed administration to liver tumors while permitting MRI/CT visualization for patient-specific confirmation of tumor-targeted delivery.

  8. Multimodal Imaging of Nanocomposite Microspheres for Transcatheter Intra-Arterial Drug Delivery to Liver Tumors

    PubMed Central

    Kim, Dong-Hyun; Li, Weiguo; Chen, Jeane; Zhang, Zhuoli; Green, Richard M.; Huang, Sui; Larson, Andrew C.

    2016-01-01

    A modern multi-functional drug carrier is critically needed to improve the efficacy of image-guided catheter-directed approaches for the treatment of hepatic malignancies. For this purpose, a nanocomposite microsphere platform was developed for selective intra-arterial transcatheter drug delivery to liver tumors. In our study, continuous microfluidic methods were used to fabricate drug-loaded multimodal MRI/CT visible microspheres that included both gold nanorods and magnetic clusters. The resulting hydrophilic, deformable, and non-aggregated microspheres were mono-disperse and roughly 25 um in size. Sustained drug release and strong MRI T2 and CT contrast effects were achieved with the embedded magnetic nano-clusters and radiopaque gold nanorods. The microspheres were successfully infused through catheters selectively placed within the hepatic artery in rodent models and subsequent distribution in the targeted liver tissues and hepatic tumors confirmed with MRI and CT imaging. These multimodal nanocomposite drug carriers should be ideal for selective intra-arterial catheter-directed administration to liver tumors while permitting MRI/CT visualization for patient-specific confirmation of tumor-targeted delivery. PMID:27405824

  9. Multimodal Imaging of Nanocomposite Microspheres for Transcatheter Intra-Arterial Drug Delivery to Liver Tumors.

    PubMed

    Kim, Dong-Hyun; Li, Weiguo; Chen, Jeane; Zhang, Zhuoli; Green, Richard M; Huang, Sui; Larson, Andrew C

    2016-07-13

    A modern multi-functional drug carrier is critically needed to improve the efficacy of image-guided catheter-directed approaches for the treatment of hepatic malignancies. For this purpose, a nanocomposite microsphere platform was developed for selective intra-arterial transcatheter drug delivery to liver tumors. In our study, continuous microfluidic methods were used to fabricate drug-loaded multimodal MRI/CT visible microspheres that included both gold nanorods and magnetic clusters. The resulting hydrophilic, deformable, and non-aggregated microspheres were mono-disperse and roughly 25 um in size. Sustained drug release and strong MRI T2 and CT contrast effects were achieved with the embedded magnetic nano-clusters and radiopaque gold nanorods. The microspheres were successfully infused through catheters selectively placed within the hepatic artery in rodent models and subsequent distribution in the targeted liver tissues and hepatic tumors confirmed with MRI and CT imaging. These multimodal nanocomposite drug carriers should be ideal for selective intra-arterial catheter-directed administration to liver tumors while permitting MRI/CT visualization for patient-specific confirmation of tumor-targeted delivery.

  10. Poly(lactic-co-glycolic) acid microspheres encapsulated in Pluronic F-127 prolong Hirudin delivery and improve functional recovery from a demyelination lesion

    PubMed Central

    Sellers, Drew L.; Kim, Tae Hee; Mount, Christopher W.; Pun, Suzie H; Horner, Philip J.

    2014-01-01

    Components of the blood have been proposed as potential therapeutic targets for improving cellular regeneration after injury and neurodegenerative disease. In this work, thrombin is shown to increase endogenous neural progenitor proliferation in the intact murine spinal cord. A local injection of heparin before a spinal cord injury reduces cell proliferation and astrogliogenesis associated with scarring. We sought to create depot-formulations of PLGA microsphere and Pluronic F-127 for sustained local delivery of two thrombin inhibitors, heparin and hirudin. Each hydrogel depot-formulation showed delayed drug release compared to microspheres or hydrogel alone. Animals with a lateral demyelination lesion showed a reduction in CD68+ macrophages when treated with hirudin-loaded PLGA/F-127 gels compared to control and heparin-treated animals. Moreover, hirudin-loaded materials showed an accelerated recovery in coordinated stepping and increased oligodendrocyte densities. Together, these data demonstrate that controlled delivery of hirudin accelerates functional recovery from a demyelination lesion in the spinal cord. PMID:25064804

  11. Poly(lactic-co-glycolic) acid microspheres encapsulated in Pluronic F-127 prolong hirudin delivery and improve functional recovery from a demyelination lesion.

    PubMed

    Sellers, Drew L; Kim, Tae Hee; Mount, Christopher W; Pun, Suzie H; Horner, Philip J

    2014-10-01

    Components of the blood have been proposed as potential therapeutic targets for improving cellular regeneration after injury and neurodegenerative disease. In this work, thrombin is shown to increase endogenous neural progenitor proliferation in the intact murine spinal cord. A local injection of heparin before a spinal cord injury reduces cell proliferation and astrogliogenesis associated with scarring. We sought to create depot-formulations of PLGA microsphere and Pluronic F-127 for sustained local delivery of two thrombin inhibitors, heparin and hirudin. Each hydrogel depot-formulation showed delayed drug release compared to microspheres or hydrogel alone. Animals with a lateral demyelination lesion showed a reduction in CD68+ macrophages when treated with hirudin-loaded PLGA/F-127 gels compared to control and heparin-treated animals. Moreover, hirudin-loaded materials showed an accelerated recovery in coordinated stepping and increased oligodendrocyte densities. Together, these data demonstrate that controlled delivery of hirudin accelerates functional recovery from a demyelination lesion in the spinal cord.

  12. Microspheres with ultrahigh holmium content for radioablation of malignancies.

    PubMed

    Bult, W; Seevinck, P R; Krijger, G C; Visser, T; Kroon-Batenburg, L M J; Bakker, C J G; Hennink, W E; van het Schip, A D; Nijsen, J F W

    2009-06-01

    The aim of this study was to develop microspheres with an ultra high holmium content which can be neutron activated for radioablation of malignancies. These microspheres are proposed to be delivered selectively through either intratumoral injections into solid tumors or administered via an intravascularly placed catheter. Microspheres were prepared by solvent evaporation, using holmium acetylacetonate (HoAcAc) crystals as the sole ingredient. Microspheres were characterized using light and scanning electron microscopy, coulter counter, titrimetry, infrared and Raman spectroscopy, differential scanning calorimetry, X-ray powder diffraction, magnetic resonance imaging (MRI), and X-ray computed tomography (CT). Microspheres, thus prepared displayed a smooth surface. The holmium content of the HoAcAc microspheres (44% (w/w)) was higher than the holmium content of the starting material, HoAcAc crystals (33% (w/w)). This was attributed to the loss of acetylacetonate from the HoAcAc complex, during rearrangement of acetylacetonate around the holmium ion. The increase of the holmium content allows for the detection of (sub)microgram amounts of microspheres using MRI and CT. HoAcAc microspheres with an ultra-high holmium content were prepared. These microspheres are suitable for radioablation of tumors by intratumoral injections or treatment of liver tumors through transcatheter administration.

  13. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    PubMed

    Zhai, Peng; Chen, X B; Schreyer, David J

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate.

  14. Optical Whispering Gallery Modes in Chalcogenide Arsenic Selenide Microspheres

    NASA Astrophysics Data System (ADS)

    Yue, Hong-Quan

    Anisotropic chalcogenide microsphere is introduced for coupling theoretical analyzing and coupling experiment. Whispering Gallery Modes (WGMs) of isotropic microsphere is introduced and the TE & TM WGMs dispersion relationship is derived from electromagnetic vector equations in the spherical coordinate. The Maxwell equations can be solved in 2D model for the 3D model of axisymmetric or Rotational symmetry isotropic microsphere. First 4 TE&TM WGMs are simulated in 2D model using finite-element weak method. The binding capability, mode volume V and quality factor Q depend on the refractive index and size of the microsphere. Plane wavefront light wave is assumed to propagate inside the microsphere; coupling coefficient is determined by WGMs numbers and the distance between the microsphere and the micro-taper. Coupling related Q factor is analyzed; TE & TM nonlinear microsphere coupling is introduced with Matlab simulation. Chalcogenide coupling experiments for transmission, reflection and drop-port function are conducted. The light waves for coupling are broadband incoherent light source and narrowband tunable laser. Broadband light gave sensitive results while the coherent laser gave easy coupling capability. The chalcogenide microsphere was used as a feedback element of an amplifying medium. Comparing with silica microsphere, chalcogenide microsphere's response is more unstable due to free carriers perturbation and thermal activity

  15. Modeling the efficiency of a magnetic needle for collecting magnetic cells

    NASA Astrophysics Data System (ADS)

    Butler, Kimberly S.; Adolphi, Natalie L.; Bryant, H. C.; Lovato, Debbie M.; Larson, Richard S.; Flynn, Edward R.

    2014-07-01

    As new magnetic nanoparticle-based technologies are developed and new target cells are identified, there is a critical need to understand the features important for magnetic isolation of specific cells in fluids, an increasingly important tool in disease research and diagnosis. To investigate magnetic cell collection, cell-sized spherical microparticles, coated with superparamagnetic nanoparticles, were suspended in (1) glycerine-water solutions, chosen to approximate the range of viscosities of bone marrow, and (2) water in which 3, 5, 10 and 100% of the total suspended microspheres are coated with magnetic nanoparticles, to model collection of rare magnetic nanoparticle-coated cells from a mixture of cells in a fluid. The magnetic microspheres were collected on a magnetic needle, and we demonstrate that the collection efficiency versus time can be modeled using a simple, heuristically-derived function, with three physically-significant parameters. The function enables experimentally-obtained collection efficiencies to be scaled to extract the effective drag of the suspending medium. The results of this analysis demonstrate that the effective drag scales linearly with fluid viscosity, as expected. Surprisingly, increasing the number of non-magnetic microspheres in the suspending fluid results increases the collection of magnetic microspheres, corresponding to a decrease in the effective drag of the medium.

  16. Functionalized magnetic nanoparticles for biomedical applications.

    PubMed

    Gudovan, Dragoș; Balaure, Paul Cătălin; Mihăiescu, Dan Eduard; Fudulu, Adrian; Purcăreanu, Bogdan; Radu, Mihai

    2015-01-01

    Functionalized magnetic nanoparticles followed two main directions in the field of biomedical applications: one direction is as image enhancing agents for magnetic resonance imaging (MRI) and the other is as drugdelivery devices for various biologically-active substances. A third field which just emerges in nanomedicine is the field of the so-called theranostic devices which combines in the same delivery vehicle both the therapeutic agent and the contrast substance. The advantages of using nanoparticles instead of larger carriers for delivery of both drug and image contrast enhancing agents will be highlighted throughout this review article. Despite the ever increasing number of articles reporting both in vitro and in vivo studies carried out on functionalized magnetic nanoparticles and envisaging their potential biomedical applications, only few formulations reached the phase of clinical trials and even fewer became marketed products. The perspectives in the field are open, since new drugs require new delivery devices and possibly new means of functionalization. At the same time, the field of nanomedicine also provides the opportunity to better exploit drugs that are already in clinical use by improving their bioavailability through appropriate nanoformulations.

  17. Leiomyoma infarction after uterine artery embolization: a prospective randomized study comparing tris-acryl gelatin microspheres versus polyvinyl alcohol microspheres.

    PubMed

    Siskin, Gary P; Beck, Avi; Schuster, Michael; Mandato, Kenneth; Englander, Meridith; Herr, Allen

    2008-01-01

    To determine the degree of leiomyoma infarction after uterine artery embolization (UAE) performed with tris-acryl gelatin microspheres or polyvinyl alcohol (PVA) microspheres. Patients determined to be candidates and scheduled for UAE were randomized prospectively to receive tris-acryl gelatin microspheres or PVA microspheres. The manufacturers' recommended technique was used for both products during the UAE procedures (including the recently described refined protocol for PVA microspheres). All patients underwent magnetic resonance (MR) imaging of the pelvis with contrast agent enhancement before and after the UAE procedure. On the postprocedural MR study, the degree of tumor infarction was assessed on postcontrast images. These findings were classified as follows: 100% infarction, 90%-99% infarction, 50%-89% infarction, and less than 50% infarction. Treatment failure was defined by enhancement of more than 10% of a patient's entire tumor burden. A total of 53 patients were enrolled in this study. Twenty-seven (mean age, 44.9 years) received PVA microspheres and 26 (mean age, 45.1 years) received tris-acryl gelatin microspheres. There were no significant differences in the preprocedural uterine volume, dominant tumor volume, location of dominant tumor, and presenting symptoms between populations. In the PVA microsphere group, treatment failure was seen in eight patients (29.6%). In the tris-acryl gelatin microsphere group, treatment failure was seen in one patient (3.8%), which was a significant difference between groups (P < or = .025). There was a significantly greater degree of tumor infarction in patients treated with tris-acryl gelatin microspheres during UAE than in patients who received PVA microspheres administered in accordance with a newly refined protocol. Given the known risk of recurrence in patients with persistent tumor enhancement after UAE, it is concluded that tris-acryl gelatin microspheres should be the preferred agent for UAE at this time.

  18. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications

    NASA Astrophysics Data System (ADS)

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R.

    2016-03-01

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0-87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI.

  19. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications.

    PubMed

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R

    2016-03-23

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0-87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI.

  20. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications

    PubMed Central

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R.

    2016-01-01

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0–87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI. PMID:27005428

  1. Metallic coating of microspheres

    SciTech Connect

    Meyer, S.F.

    1980-08-15

    Extremely smooth, uniform metal coatings of micrometer thicknesses on microscopic glass spheres (microspheres) are often needed as targets for inertial confinement fusion (ICF) experiments. The first part of this paper reviews those methods used successfully to provide metal coated microspheres for ICF targets, including magnetron sputtering, electro- and electroless plating, and chemical vapor pyrolysis. The second part of this paper discusses some of the critical aspects of magnetron sputter coating of microspheres, including substrate requirements, the sticking of microspheres during coating (preventing a uniform coating), and the difficulties in growing the desired dense, smooth, uniform microstructure on continuously moving spherical substrates.

  2. Synthesis and characterization of magnetic chitosan microspheres as low-density and low-biotoxicity adsorbents for lake restoration.

    PubMed

    Funes, A; de Vicente, J; de Vicente, I

    2017-03-01

    We propose a novel magnetic adsorbent for optimal Phosphorus (P) removal from the upper sediment layers. For this aim, magnetic chitosan microparticles were prepared using a reverse-phase suspension cross-linking technique. The resulting particles and suspensions were characterized using scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, magnetometry, thermogravimetric analysis, electrophoretic mobility and turbidity measurements. The hybrids are multicore particles consisting of well dispersed magnetite nanoparticles (approx. 10% w/w) homogeneously distributed within the biopolymer matrix. These microparticles can be easily separated from the water column and sediment using magnetic field gradients. Their P adsorption capacity is evaluated in batch conditions resulting in a maximum P adsorption capacity of ML = 4.84 mg g(-1) at pH = 7. We demonstrate that these particles are excellent candidates to remove P from water column and also P mobile from the upper sediment layers due to two main reasons: they sediment slower and present lower potential toxicity (due to a their larger size) than conventional iron/iron oxide microparticles previously proposed for lake restoration.

  3. Simulating functional magnetic materials on supercomputers.

    PubMed

    Gruner, Markus Ernst; Entel, Peter

    2009-07-22

    The recent passing of the petaflop per second landmark by the Roadrunner project at the Los Alamos National Laboratory marks a preliminary peak of an impressive world-wide development in the high-performance scientific computing sector. Also, purely academic state-of-the-art supercomputers such as the IBM Blue Gene/P at Forschungszentrum Jülich allow us nowadays to investigate large systems of the order of 10(3) spin polarized transition metal atoms by means of density functional theory. Three applications will be presented where large-scale ab initio calculations contribute to the understanding of key properties emerging from a close interrelation between structure and magnetism. The first two examples discuss the size dependent evolution of equilibrium structural motifs in elementary iron and binary Fe-Pt and Co-Pt transition metal nanoparticles, which are currently discussed as promising candidates for ultra-high-density magnetic data storage media. However, the preference for multiply twinned morphologies at smaller cluster sizes counteracts the formation of a single-crystalline L1(0) phase, which alone provides the required hard magnetic properties. The third application is concerned with the magnetic shape memory effect in the Ni-Mn-Ga Heusler alloy, which is a technologically relevant candidate for magnetomechanical actuators and sensors. In this material strains of up to 10% can be induced by external magnetic fields due to the field induced shifting of martensitic twin boundaries, requiring an extremely high mobility of the martensitic twin boundaries, but also the selection of the appropriate martensitic structure from the rich phase diagram.

  4. Porous ZnS/ZnO microspheres prepared through the spontaneous organization of nanoparticles and their application as supports of holding CdTe quantum dots

    SciTech Connect

    Cao Xuebo Lan Xianmei; Zhao Cui; Shen Wenjun; Yao Dan

    2008-05-06

    This manuscript describes a self-organization method for the large-scale production of porous ZnS/ZnO composite microspheres and their application as supports of CdTe quantum dots. Through the reaction of Zn{sup 2+} and urea and thioacetamide at 85 deg. C for 10 min, nanoparticles of cubic ZnS and amorphous ZnO were formed and they present a strong tendency to organize into regular microspheres. The formation of nanopores within the microspheres is related to Ostwald ripening: some small nanoparticles within the microspheres were merged by the larger ones, and as a result, numerous nanopores were generated. Furthermore, when a solvothermal ripening is applied for the porous microspheres, the components within them can be transformed into hexagonal ZnS and ZnO. CdTe quantum dots were introduced into the nanopores to achieve luminescent microspheres through in situ nucleation and growth. And it is expected that, besides semiconducting quantum dots, other functional units, such as magnetic and catalytically activated nanoparticles, can also be introduced into them.

  5. Superparamagnetic folate-immobilized dye labeled microspheres for oral cancer screening

    NASA Astrophysics Data System (ADS)

    Liesenfeld, Bernd

    A design concept is presented and developed for a screening test for oral cancer. The application is based on generating specific binding between microspheres and receptors known to be expressed specifically on malignant cells. Quantification of the test is derived from a ratiometric determination of test microspheres immobilized with folate against control microspheres. Microspheres were suspension copolymerized polymethyl methacrylate and aminoethyl methacrylate, and were doped with superparamagnetic iron oxide to permit magnetic separation of microspheres from testing suspension. Magnetic separation was demonstrated. Specific binding was provided by folic acid that was immobilized on the microsphere surface by carbodiimide chemistry. Microsphere labeling was performed by covalent bonding of fluorophores to monomers prior to polymerization, permitting spatial imaging of microspheres by fluorescence microscopy. Testing of specific binding of folate to tumorous cell lines was performed using cell lines known to overexpress folate receptors. Cell lines used included NCI-H23 human lung adenocarcinoma, with controls provided by normal human dermal fibroblasts. It was found that the folate-immobilized microspheres were preferentially retained by the tumourous cell line, relative to control microspheres (p = 0.0074). There was no significant difference between the retention of folate-immobilized microspheres by the cancerous cell line as compared to the control cell line (p = 0.90) as determined by pooled data. Testing of specific binding to relevant tissue was performed using excised oral cancer tissue that had been frozen and sectioned onto slides. It was found that the folate immobilized microspheres were retained by the cancerous tissue at a higher rate than the control microspheres (p = 0.037). Controls performed with normal tissue shows that the folate-immobilized microspheres were retained by normal tissue at a higher rate than the cancerous tissue. Both cell

  6. Functional magnetic resonance imaging studies of language.

    PubMed

    Small, Steven L; Burton, Martha W

    2002-11-01

    Functional neuroimaging of language builds on almost 150 years of study in neurology, psychology, linguistics, anatomy, and physiology. In recent years, there has been an explosion of research using functional imaging technology, especially positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), to understand the relationship between brain mechanisms and language processing. These methods combine high-resolution anatomic images with measures of language-specific brain activity to reveal neural correlates of language processing. This article reviews some of what has been learned about the neuroanatomy of language from these imaging techniques. We first discuss the normal case, organizing the presentation according to the levels of language, encompassing words (lexicon), sound structure (phonemes), and sentences (syntax and semantics). Next, we delve into some unusual language processing circumstances, including second languages and sign languages. Finally, we discuss abnormal language processing, including developmental and acquired dyslexia and aphasia.

  7. Immobilization of silver nanoparticles on silica microspheres

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Kai; Chen, Chia-Yin; Han, Jin-Lin; Chen, Chii-Chang; Jiang, Meng-Dan; Hsu, Jen-Sung; Chan, Chia-Hua; Hsieh, Kuo-Huang

    2010-01-01

    The silver nanoparticles (Ag NPs) have been immobilized onto silica microspheres through the adsorption and subsequent reduction of Ag+ ions on the surfaces of the silica microspheres. The neat silica microspheres that acted as the core materials were prepared through sol-gel processing; their surfaces were then functionalized using 3-mercaptopropyltrimethoxysilane (MPTMS). The major aims of this study were to immobilize differently sized Ag particles onto the silica microspheres and to understand the mechanism of formation of the Ag nano-coatings through the self-assembly/adsorption behavior of Ag NPs/Ag+ ions on the silica spheres. The obtained Ag NP/silica microsphere conglomerates were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). Their electromagnetic wave shielding effectiveness were also tested and studied. The average particle size of the obtained Ag NPs on the silica microsphere was found that could be controllable (from 2.9 to 51.5 nm) by adjusting the ratio of MPTMS/TEOS and the amount of AgNO3.

  8. Micron-sized surface enhanced Raman scattering reporter/fluorescence probe encoded colloidal microspheres for sensitive DNA detection.

    PubMed

    You, Lijun; Li, Ruimin; Dong, Xu; Wang, Fang; Guo, Jia; Wang, Changchun

    2017-02-15

    A new type of optical probes, featuring surface enhanced Raman scattering (SERS) and fluorescence spectra dual-mode encoding, has been reported in this article. Based on the uniform micrometer-sized melamine resin/Ag nanoparticles (MRM/Ag-NPs) composite microspheres, the SERS reporters and fluorescent probes were successfully fixed onto the different layers of the MEM/Ag-NPs microspheres, which supported the sensitive DNA detecton. The two spectroscopic methods commonly considered to be contradictive to each other, yet the optical signals were separable in the experiments. The dual-encoding strategy and single microsphere detecton method put the number of available independent codes to be rough the multiple of those available in the two optical detection channels, which increases far more rapidly than the summation of the two channels. As a proof of cencept, the utility of this dual spectrum mode SERS-fluoresecence encoded microsphere (SFEM) was demonstrated in a specific DNA detection using complimentary ssDNA functionalized magnetic beads as the DNA capturing and separation agents. Excellent encoding results were demonstrated from the decoding of the SERS and fluorescence signals of the SFEM. The method appears to be general in scope and we expect that the SERS-fluoresecence encoded microspheres system is applicable to multiplex bioassays of a variety of biomolecules.

  9. Hydrophilic gallic acid-imprinted polymers over magnetic mesoporous silica microspheres with excellent molecular recognition ability in aqueous fruit juices.

    PubMed

    Hu, Xin; Xie, Lianwu; Guo, Junfang; Li, Hui; Jiang, Xinyu; Zhang, Yuping; Shi, Shuyun

    2015-07-15

    Hydrophilic molecularly imprinted polymers (MIPs) for gallic acid (GA) were prepared with excellent recognition ability in an aqueous solution. The proposed MIPs were designed by self-polymerization of dopamine (DA) on magnetic mesoporous silica (Fe3O4@SiO2@mSiO2, MMS) using GA as template. Resulting Fe3O4@SiO2@mSiO2@MIPs (MMS-MIPs) were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM), and evaluated by adsorption isotherms/kinetics and competitive adsorption. The adsorption behavior between GA and MMS-MIPs followed Langmuir and Sips adsorption isotherms with a maximum adsorption capacity at 88.7 mg/g and pseudo-second-order reaction kinetics with fast binding (equilibrium time at 100 min). In addition, MMS-MIPs showed rapid magnetic separation (10 s) and stability (retained 95.2% after six cycles). Subsequently, MMS-MIPs were applied for the selective extraction and determination of GA from grape, apple, peach and orange juices (4.02, 3.91, 5.97, and 0.67 μg/g, respectively). Generally, the described method may pave the way towards rationally designing more advanced hydrophilic MIPs.

  10. Making Polymeric Microspheres

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Hyson, Michael T.; Chung, Sang-Kun; Colvin, Michael S.; Chang, Manchium

    1989-01-01

    Combination of advanced techniques yields uniform particles for biomedical applications. Process combines ink-jet and irradiation/freeze-polymerization techniques to make polymeric microspheres of uniform size in diameters from 100 to 400 micrometer. Microspheres used in chromatography, cell sorting, cell labeling, and manufacture of pharmaceutical materials.

  11. Making Polymeric Microspheres

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Hyson, Michael T.; Chung, Sang-Kun; Colvin, Michael S.; Chang, Manchium

    1989-01-01

    Combination of advanced techniques yields uniform particles for biomedical applications. Process combines ink-jet and irradiation/freeze-polymerization techniques to make polymeric microspheres of uniform size in diameters from 100 to 400 micrometer. Microspheres used in chromatography, cell sorting, cell labeling, and manufacture of pharmaceutical materials.

  12. Production of hollow aerogel microspheres

    SciTech Connect

    Upadhye, R.S.; Henning, S.A.

    1990-12-31

    A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  13. Production of hollow aerogel microspheres

    DOEpatents

    Upadhye, Ravindra S.; Henning, Sten A.

    1993-01-01

    A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  14. Preparation and electromagnetic properties of core/shell polystyrene@polypyrrole@nickel composite microspheres.

    PubMed

    Li, Wenzhe; Qiu, Teng; Wang, Leilei; Ren, Shanshan; Zhang, Jiangru; He, Lifan; Li, Xiaoyu

    2013-02-01

    Through a novel method, we successfully synthesized electromagnetic (EM) functional polystyrene@polypyrrole@nickel (PS@PPy@Ni) composite microspheres. The PS@PPy spheres with well-defined core/shell structure have been synthesized via an in situ chemical oxidative copolymerization of pyrrole (Py) and N-2-carboxyethylpyrrole (PyCOOH) templated by PS microspheres. The reaction was carried out under heterophase conditions using the mixture of ethanol and water as the continuous phase. Tailored by the carboxyl groups on the surface of microspheres, magnetic nickel layer has been steady deposited onto the P(Py-PyCOOH) layer of the microspheres through an activation-electroless plating technology. The fine PS@P(Py-PyCOOH)@Ni core/shell structures could be obtained with the PyCOOH content up to 50 wt % in the P(Py-PyCOOH) layer. Moreover, the as-prepared PS@P(Py-PyCOOH)@Ni composites are ferromagnetic materials and behave as a good electromagnetic (EM) absorption material due to the coating of Ni layer around the PS@P(Py-PyCOOH) spheres. The PS@P(Py-PyCOOH)@Ni composite spheres show the remarkable EM wave absorption property with the maximum reflection loss (around -20.06 dB) at 10.69 GHz. The EM wave absorption can retained lower than -10 dB within a broad frequency range from 9.16 to 13.75 GHz.

  15. Sensitive Flexible Magnetic Sensors using Organic Transistors with Magnetic-Functionalized Suspended Gate Electrodes.

    PubMed

    Zang, Yaping; Zhang, Fengjiao; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

    2015-12-22

    Utilizing a magnetic-functionalized suspended gate with combined features of outstanding conductivity, flexibility, and magnetic properties, flexible magnetic sensor based on an organic field-effect transistor (OFET), with a high sensitivity of 115.2% mT(-1) is demonstrated. Gate engineering enables the sensing devices to possess promising applications for flexible touchless switches and spatiallyresolved magnetic-imaging elements.

  16. Functionalized magnetic nanoparticles: A novel heterogeneous catalyst support

    EPA Science Inventory

    Functionalized magnetic nanoparticles have emerged as viable alternatives to conventional materials, as robust, high-surface-area heterogeneous catalyst supports. Post-synthetic surface modification protocol for magnetic nanoparticles has been developed that imparts desirable che...

  17. Functionalized magnetic nanoparticles: A novel heterogeneous catalyst support

    EPA Science Inventory

    Functionalized magnetic nanoparticles have emerged as viable alternatives to conventional materials, as robust, high-surface-area heterogeneous catalyst supports. Post-synthetic surface modification protocol for magnetic nanoparticles has been developed that imparts desirable che...

  18. Incorporation of iron oxide nanoparticles and quantum dots into silica microspheres.

    PubMed

    Insin, Numpon; Tracy, Joseph B; Lee, Hakho; Zimmer, John P; Westervelt, Robert M; Bawendi, Moungi G

    2008-02-01

    We describe the synthesis of magnetic and fluorescent silica microspheres fabricated by incorporating maghemite (gamma-Fe2O3) nanoparticles (MPs) and CdSe/CdZnS core/shell quantum dots (QDs) into a silica shell around preformed silica microspheres. The resultant approximately 500 nm microspheres have a narrow size distribution and show uniform incorporation of QDs and MPs into the shell. We have demonstrated manipulation of these microspheres using an external magnetic field with real-time fluorescence microscopy imaging.

  19. Acoustic noise during functional magnetic resonance imaging.

    PubMed

    Ravicz, M E; Melcher, J R; Kiang, N Y

    2000-10-01

    Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For studies of the auditory system, acoustic noise generated during fMRI can interfere with assessments of this activation by introducing uncontrolled extraneous sounds. As a first step toward reducing the noise during fMRI, this paper describes the temporal and spectral characteristics of the noise present under typical fMRI study conditions for two imagers with different static magnetic field strengths. Peak noise levels were 123 and 138 dB re 20 microPa in a 1.5-tesla (T) and a 3-T imager, respectively. The noise spectrum (calculated over a 10-ms window coinciding with the highest-amplitude noise) showed a prominent maximum at 1 kHz for the 1.5-T imager (115 dB SPL) and at 1.4 kHz for the 3-T imager (131 dB SPL). The frequency content and timing of the most intense noise components indicated that the noise was primarily attributable to the readout gradients in the imaging pulse sequence. The noise persisted above background levels for 300-500 ms after gradient activity ceased, indicating that resonating structures in the imager or noise reverberating in the imager room were also factors. The gradient noise waveform was highly repeatable. In addition, the coolant pump for the imager's permanent magnet and the room air-handling system were sources of ongoing noise lower in both level and frequency than gradient coil noise. Knowledge of the sources and characteristics of the noise enabled the examination of general approaches to noise control that could be applied to reduce the unwanted noise during fMRI sessions.

  20. Noble Metal Nanoparticle-loaded Mesoporous Oxide Microspheres for Catalysis

    NASA Astrophysics Data System (ADS)

    Jin, Zhao

    reaction, I found that Pd nanoparticles supported on mesoporous TiO2 exhibit the best catalytic performance. The demonstrated low-cost and high-productivity preparation method can be extended to other catalysts, which can contain various metals and oxide substrates and will have high potential for industrial applications. Our preparation method also provides a platform for the studies of the synergetic catalytic effects between different oxide substrates and metals. I further fabricated hollow mesoporous microspheres containing differently shaped noble metal nanocrystals. Hollow structures are strongly desired in many applications because of their high pore volumes, surface areas, and possible light-trapping effect. In my study, the hollow structures were obtained by simply dispersing polystyrene (PS) nanospheres into the precursor solution for aerosol spray. The PS spheres were removed by thermal calcination to produce hollow mesoporous microspheres. In my first study, the noble metal salts were dissolved in the precursor solutions, and the noble metal nanoparticles were obtained through thermal calcination. In this way, the size and shape of the metal nanoparticles cannot be well controlled. In my second study, I first grew noble metal nanocrystals and then incorporated them into the oxide supports. This preparation route allowed me to incorporate metal nanocrystals with controlled sizes, shapes, and compositions into the oxide matrices. The metal nanocrystals I used in this experiment included Pd nanocubes, Au nanorods, and Au core--Pd shell nanorods. These nanocrystals were functionalized with thiol-terminated methoxypoly(ethylene glycol) . The surface functionalization allowed them to adsorb on the PS spheres. After thermal calcination, the noble metal nanocrystals were left inside and adsorbed on the inner surface of the hollow mesoporous metal oxide microspheres. I investigated the catalytic activities of the Pd nanocube-embedded hollow mesoporous TiO2 and ZrO2

  1. Microsphere Insulation Panels

    NASA Technical Reports Server (NTRS)

    Mohling, R.; Allen, M.; Baumgartner, R.

    2006-01-01

    Microsphere insulation panels (MIPs) have been developed as lightweight, longlasting replacements for the foam and vacuum-jacketed systems heretofore used for thermally insulating cryogenic vessels and transfer ducts. The microsphere core material of a typical MIP consists of hollow glass bubbles, which have a combination of advantageous mechanical, chemical, and thermal-insulation properties heretofore available only separately in different materials. In particular, a core filling of glass microspheres has high crush strength and low density, is noncombustible, and performs well in soft vacuum.

  2. Overview of Functional Magnetic Resonance Imaging

    PubMed Central

    Glover, Gary H.

    2010-01-01

    Synopsis Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) depicts changes in deoxyhemoglobin concentration consequent to task-induced or spontaneous modulation of neural metabolism. Since its inception in 1990, this method has been widely employed in thousands of studies of cognition for clinical applications such as surgical planning, for monitoring treatment outcomes, and as a biomarker in pharmacologic and training programs. Technical developments have solved most of the challenges of applying fMRI in practice. These challenges include low contrast to noise ratio of BOLD signals, image distortion, and signal dropout. More recently, attention is turning to the use of pattern classification and other statistical methods to draw increasingly complex inferences about cognitive brain states from fMRI data. This paper reviews the methods, some of the challenges and the future of fMRI. PMID:21435566

  3. Synthesis and drug-loading properties of folic acid-modified superparamagnetic Fe3O4 hollow microsphere core/mesoporous SiO2 shell composite particles

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Guo, Xue; Wei, Kaiwei; Wang, Lijuan; Yang, Dandan; Lai, Lifang; Cheng, Meiling; Liu, Qi

    2014-01-01

    A drug delivery system, which not only has superparamagnetic property, higher surface area but also has targeting function, has been developed. The core/shell structural magnetic magnetite mesoporous silica microspheres with amine groups (Fe3O4-SiO2-NH2) were first fabricated by a one-pot direct co-condensation method, then folic acid-modified magnetic mesoporous silica composite microspheres (Fe3O4-SiO2-NHFA) were obtained by the bonding of the Fe3O4-SiO2-NH2 with folic acid as targeted molecule. The resultant composite microspheres were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, low temperature nitrogen adsorption-desorption, and vibrating sample magnetometer. A well-known inflammational drug ibuprofen was used as a model drug to assess the loading and releasing behavior of the composite microspheres. Fe3O4-SiO2-NHFA system exhibits magnetic properties typical for superparamagnetic material with a higher saturation magnetization value of about 41.2 emu/g and has better capacity of drug storage (32.0 %) and sustained drug-release property. So this system has potential applications in biomedical field.

  4. Organic aerogel microspheres

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1999-06-01

    Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  5. Organic aerogel microspheres

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  6. Compartmentalization in proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Brooke, S.; Fox, S. W.

    1977-01-01

    Proteinoid microspheres with stable internal compartments and internal structure are made from acidic proteinoid and basic proteinoid with calcium. The populations of microspheres are characterized by a wide diversity of structure. A model of primitive intracellular communication is suggested by the observed movement of internal particles between compartments of a multicompartmentalized unit. Differential response to pH change and to temperature change has been demonstrated within one population and suggests one mode of adaptive selection among primordial cell populations.

  7. The prognostic value of functional and anatomical parameters for the selection of patients receiving yttrium-90 microspheres for the treatment of liver cancer

    NASA Astrophysics Data System (ADS)

    Mesoloras, Geraldine

    Yttrium-90 (90Y) microsphere therapy is being utilized as a treatment option for patients with primary and metastatic liver cancer due to its ability to target tumors within the liver. The success of this treatment is dependent on many factors, including the extent and type of disease and the nature of prior treatments received. Metabolic activity, as determined by PET imaging, may correlate with the number of viable cancer cells and reflect changes in viable cancer cell volume. However, contouring of PET images by hand is labor intensive and introduces an element of irreproducibility into the determination of functional target/tumor volume (FTV). A computer-assisted method to aid in the automatic contouring of FTV has the potential to substantially improve treatment individualization and outcome assessment. Commercial software to determine FTV in FDG-avid primary and metastatic liver tumors has been evaluated and optimized. Volumes determined using the automated technique were compared to those from manually drawn contours identified using the same cutoff in the standard uptake value (SUV). The reproducibility of FTV is improved through the introduction of an optimal threshold value determined from phantom experiments. Application of the optimal threshold value from the phantom experiments to patient scans was in good agreement with hand-drawn determinations of the FTV. It is concluded that computer-assisted contouring of the FTV for primary and metastatic liver tumors improves reproducibility and increases accuracy, especially when combined with the selection of an optimal SUV threshold determined from phantom experiments. A method to link the pre-treatment assessment of functional (PET based) and anatomical (CT based) parameters to post-treatment survival and time to progression was evaluated in 22 patients with colorectal cancer liver metastases treated using 90Y microspheres and chemotherapy. The values for pre-treatment parameters that were the best

  8. Preparation of molecular imprinted microspheres based on inorganic-organic co-functional monomer for miniaturized solid-phase extraction of fluoroquinolones in milk.

    PubMed

    Wang, Hui; Wang, Ruiling; Han, Yehong

    2014-02-15

    An inorganic-organic co-functional monomer, methacrylic acid-vinyltriethoxysilan (MAA-VTES) was designed for the synthesis of molecularly imprinted microspheres (MIMs). By virtue of the aqueous suspension polymerization and dummy template (pazufloxacin), the obtained MAA-VTES based MIMs exhibited good recognition and selectivity to fluoroquinolones (FQs), and were successfully applied as selective sorbents of a miniaturized home-made solid phase extraction device for the determination of ofloxacin (OFL), lomefloxacin (LOM) and ciprofloxacin (CIP) in milk samples. Under the optimum conditions of the miniaturized molecularly imprinted solid phase extraction (mini-MISPE) coupled with liquid chromatography-ultraviolet detector (LC-UV), good linearities were obtained for three FQs in a range of 0.2-20.0μgmL(-1) and the average recoveries at three spiked levels were ranged from 87.2% to 106.1% with the relative standard deviation (RSD) less than 5.4%. The presented co-functional monomer based mini-MISPE-LC-UV protocol introduced the rigidity and flexibility of inorganic silicon materials, exhibited excellent extraction performance towards targets, and could be potentially applied to the determination of FQs in milk samples.

  9. Normal and abnormal function of the pacemaker magnetic reed switch.

    PubMed

    Driller, J; Barold, S S; Parsonnet, V

    1976-01-01

    Application of the special test magnet over a demand pacemaker actuates a magnetic reed switch which converts the pacemaker to fixed-rate pacing. The magnetic reed switch is a simple and generally very reliable component. This review discusses the normal and abnormal functions of the pacemaker magnetic reed switch. An understanding of the theoretical and practical aspects of this subject is important in the overall management of patients with implanted pacemakers.

  10. Method for sizing hollow microspheres

    DOEpatents

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  11. Functional Nanostructures for Magnetic and Energy Application

    NASA Astrophysics Data System (ADS)

    Zhou, Minjie

    Functional nanostructures serve as the basic building blocks for nanodevices and significant efforts have been devoted to their morphology control and properties optimization. In present study, four functional nanostructures, i.e., FePt/B4C multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite film, Ga-doped ZnO nanowire arrays, and CdSe nanotube arrays are designed, synthesized and characterized in detail, in which the first two are expected to be prominent candidates for ultrahigh-density magnetic storage media while the later two have potential applications in solar energy conversion. FePt/B4C multilayer thin films are deposited on silicon substrates using magnetron sputtering with different B4C layer thickness. Experimental results suggest that the B4C layers effectively serve as spacers to separate the FePt layers, making the multilayer configuration stable even after film annealing at elevated temperatures. On the other hand, B and C are found to be incorporated into the FePt layer, which is responsible for the FePt grain growth confinement and grain separation, and eventually affects the properties of the composite film. Based on the experimental results of multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite thin films on Si substrate are synthesized, in which a record coercivity of 2200 Oe is achieved compared to similar system. The size uniformity of the FePt nanoparticles, the well-defined particle-particle separation, together with the good magnetic property and high temperature thermal stability of the overall composite film, make it a very promising candidate for the ultrahigh density magnetic storage media. Semiconductor based one-dimensional nanostructures are investigated as promising building blocks for solar energy conversion devices. Two aspects are explored, aiming at increasing the energy conversion efficiency, i.e., facilitating electron transport and enhancing photon absorbing. In the first case

  12. Histidine-functionalized carbon-based dot-Zinc(II) nanoparticles as a novel stabilizer for Pickering emulsion synthesis of polystyrene microspheres.

    PubMed

    Ruiyi, Li; Zaijun, Li; Junkang, Liu

    2017-05-01

    Carbon-based dots (CDs) are nanoparticles with size-dependent optical and electronic properties that have been widely applied in energy-efficient displays and lighting, photovoltaic devices and biological markers. However, conventional CDs are difficult to be used as ideal stabilizer for Pickering emulsion due to its irrational amphiphilic structure. The study designed and synthesized a new histidine-functionalized carbon dot-Zinc(II) nanoparticles, which is termed as His-CD-Zn. The His-CD was made via one-step hydrothermal treatment of histidine and maleic acid. The His-CD reacted with Zn(2+) to form His-CD-Zn. The as-prepared His-CD-Zn was used as a solid particle surfactant for stabilizing styrene-in-water emulsion. The Pickering emulsion exhibits high stability and sensitive pH-switching behaviour. The introduction of S2O8(2-) triggers the emulsion polymerization of styrene. The resulted polystyrene microsphere was well coated with His-CDs on the surface. It was successfully used as an ideal adsorbent for removal of heavy metallic ions from water with high adsorption capacity. The study also provides a prominent approach for fabrication of amphiphilic carbon-based nanoparticles for stabilizing Pickering emulsion.

  13. Highly sensitive optical sensor that detects Hg2+ and Cu2+ by immobilizing dicarboxylate 1,5-diphenyl-3-thiocarbazone on surface functionalized PVA microspheres

    NASA Astrophysics Data System (ADS)

    Bai, Xue; Gu, Haixin; Hua, Zulin; Dai, Zhangyan; Yang, Bei; Li, Yulong

    2015-11-01

    A novel optical sensor to detect Hg2+ and Cu2+ is prepared by immobilizing a synthesized dicarboxylate 1,5-diphenyl-3-thiocarbazone (DDT) group on functionalized polyvinyl alcohol (PVA) microspheres. This optical sensor is successfully fabricated by extensive characterization with Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Its colorimetric properties, selectivity, sensitivity, and reversibility are investigated as well. In this sensing system, DDT-PVA selectively recognized multiple heavy metal ions, as indicated by the changes in color from orange to scarlet for Hg2+ and from orange to gray for Cu2+. In particular, this optical sensor exhibits the most apparent color changes at pH levels of 12 and 2. Hence, Hg2+ and Cu2+ can be detected in aqueous solution at minimum detection limits of 0.053 and 0.132 μM, respectively, with a UV-vis spectrometer. Furthermore, the sensor can be regenerated by ethylene diamine tetraacetic acid and reused several times. Therefore, the optical sensor can detect Hg2+ because of its selectivity, sensitivity, and reversibility.

  14. Excitation of silicon microspheres resonances with femtosecond laser fabricated glass waveguides

    NASA Astrophysics Data System (ADS)

    Ćirkinoǧlu, Hüseyin Ozan; Gökay, Ulaş Sabahattin; Serpengüzel, Ali; Sotillo, Belén.; Bharadwaj, Vibhav; Eaton, Shane M.; Ramponi, Roberta

    2016-09-01

    Optical waveguides were fabricated with femtosecond pulsed lasers on glass and characterized by transmission measurements. Glass waveguides were later used for excitation of the whispering gallery modes in a silicon microsphere. The coupling between the silicon microsphere and the femtosecond laser inscribed optical waveguide was simulated in both 90° elastic scattering and 0° transmission spectra. The silicon microsphere whispering gallery modes are available for both in the transverse electric and transverse magnetic polarizations with a spectral mode spacing of 0.25 nm. Optical resonances on silicon microsphere integrated with femtosecond laser written optical waveguides may lead to future quantum optical communication devices.

  15. Functional magnetic resonance imaging of the retina.

    PubMed

    Duong, Timothy Q; Ngan, Shing-Chung; Ugurbil, Kamil; Kim, Seong-Gi

    2002-04-01

    This study explored the feasibility of mapping the retina's responses to visual stimuli noninvasively, by using functional magnetic resonance imaging (fMRI). fMRI was performed on a 9.4-Tesla scanner to map activity-evoked signal changes of the retina-choroid complex associated with visual stimulation in anesthetized cats (n = 6). Three to 12 1-mm slices were acquired in a single shot using inversion-recovery, echo-planar imaging with a nominal in-plane resolution of 468 x 468 microm(2). Visual stimuli were presented to the full visual field and to the upper and lower visual fields. The stimuli were drifting or stationary gratings, which were compared with the dark condition. Activation maps were computed using cross-correlation analysis and overlaid on anatomic images. Multislice activation maps were reconstructed and flattened onto a two-dimensional surface. fMRI activation maps showed robust increased activity in the retina-choroid complex after visual stimulation. The average stimulus-evoked fMRI signal increase associated with drifting-grating stimulus was 1.7% +/- 0.5% (P < 10(-4), n = 6) compared with dark. Multislice functional images of the retina flattened onto a two-dimensional surface showed relatively uniform activation. No statistically significant activation was observed in and around the optic nerve head. Hemifield stimulation studies demonstrated that stimuli presented to the upper half of the visual field activated the lower part of the retina, and stimuli presented to the lower half of the visual field activated the upper part of the retina, as expected. Signal changes evoked by the stationary gratings compared with the dark basal condition were positive but were approximately half that evoked by the drifting gratings (1.0% +/- 0.1% versus 2.1% +/- 0.3%, P < 10(-4)). To the best of our knowledge, this is the first fMRI study of the retina, demonstrating its feasibility in imaging retinal function dynamically in a noninvasive manner and at

  16. Synthesis of SPIO-chitosan microspheres for MRI-detectable embolotherapy

    NASA Astrophysics Data System (ADS)

    Lee, Hyo Sook; Hee Kim, Eun; Shao, Huiping; Kook Kwak, Byung

    2005-05-01

    Spherical SPIO nanoparticles were synthesized and embedded in polyglucosamine (chitosan) by a sonochemical method. The embedded microspheres were shifted out in the range of 100-150 μm. The microspheres were injected into the kidney of a New Zealand white rabbit via an angiographic catheter, and detected in magnetic resonance images of the kidney.

  17. A simple approach to the synthesis of hollow microspheres with magnetite/silica hybrid walls.

    PubMed

    Liu, Jia; Deng, Yonghui; Liu, Chong; Sun, Zhenkun; Zhao, Dongyuan

    2009-05-01

    In this paper, we report a simple approach for templating synthesis of magnetic hollow composite microspheres with magnetite/silica walls. This approach is based on the co-sedimentation of polymer microspheres and magnetic colloids followed by impregnation with silica oligomer from tetraethyl orthosilicate and the further removal of the polymer microspheres by pyrolysis. The diameter of the hollow microspheres can be adjusted in range of 300 nm-2.0 microm by using polymer microspheres of different sizes and the wall thickness is tunable from 10-50 nm by controlling ratio of magnetite to the polymer microspheres. Magnetic characterizations show that the hollow microspheres have superparamagnetism with magnetization saturation of 10-30 emu/g. HRTEM and N(2) adsorption-desorption isotherms reveal that the hollow microspheres have numerous nanopores in the walls with a broad distribution in the range of 2 to 80 nm, which results in a high BET surface (67.6 m(2)/g) and pores volume (0.14 cm(3)/g).

  18. Properties of Magnetic Reconnection as a function of magnetic shear

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Daughton, W. S.; Karimabadi, H.; Li, H.; Gary, S. P.; Guo, F.

    2013-12-01

    Observations of reconnection events at the Earth's magnetopause and in the solar wind show that reconnection occurs for a large range in magnetic shear angles extending to the very low shear limit 1. Here we report a fully kinetic study of the influence of the magnetic shear on details of reconnection such as its structure and rate. In previous work, we found that the electron diffusion region bifurcates into two or more distinct layers in regimes with weak magnetic shear2, a new feature that may be observable by NASA's up-coming Magnetospheric Multiscale mission. In this work, we have systematically extended the study to lower shear cases and found a new regime, where the reconnection electric field becomes much smaller and the properties of the reconnection changes significantly. We will discuss the role of various physics mechanisms in determining the observed scaling of the reconnection rate, including the dispersive properties of the waves in the system, the dissipation mechanisms and the tearing instability. 1 J. T. Goslings and T. D. Phan. APJL 763, L39, 2013 2 Yi-Hsin Liu et al. Phys. Rev. Lett. 110 , 265004, 2013

  19. Increase in stability of cellulase immobilized on functionalized magnetic nanospheres

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjuan; Qiu, Jianhui; Feng, Huixia; Zang, Limin; Sakai, Eiichi

    2015-02-01

    Functionalized magnetic nanospheres were prepared by co-condensation of tetraethylorthosilicate with three different amino-silanes: 3-(2-aminoethylamino propyl)-triethoxysilane (AEAPTES), 3-(2-aminoethylamino propyl)-trimethoxysilane (AEAPTMES) and 3-aminopropyltriethoxysilane (APTES). Then three functionalized magnetic nanospheres were used as supports for immobilization of cellulase. The three functionalized magnetic nanospheres with core-shell morphologies exhibited higher capacity for cellulase immobilization than unfunctionalized magnetic nanospheres. The increasing of surface charge of functionalized magnetic nanospheres leads to an enhancement of the capacity of cellulase immobilization. Particularly, AEAPTMES with methoxy groups was favored to be hydrolyzed and grafted on unfunctionalized magnetic nanospheres than the others. AEAPTMES functionalized magnetic nanospheres with the highest zeta potential (29 mV) exhibited 87% activity recovery and the maximum amount of immobilized cellulase was 112 mg/g support at concentration of initial cellulase of 8 mg/mL. Immobilized cellulase on AEAPTMES functionalized magnetic nanospheres had higher temperature stability and broader pH stability than other immobilized cellulases and free cellulase. In particular, it can be used in about 40 °C, demonstrating the potential of biofuel production using this immobilized cellulase.

  20. Magnetic solid-phase extraction and determination of puerarin in rat plasma using C(18)-functionalized magnetic silica nanoparticles by high performance liquid chromatography.

    PubMed

    Wang, Qi; Huang, Lijie; Yu, Panfeng; Wang, Jianchang; Shen, Shun

    2013-01-01

    In the paper, we presented a magnetic solid-phase extraction (MSPE) method based on C(18)-functionalized magnetic silica nanoparticles for the analysis of puerarin in rat plasma. The approach involves two steps including synthesis of magnetic solid-phase sorbents and bioanalysis. The synthesized magnetic silica microspheres modified with chloro(dimethyl)octylsilane (namely Fe(3)O(4)@SiO(2)-C(18)) can provide an efficient way for the extraction of puerarin through C(18) hydrophobic interaction. The puerarin could be easily enriched using milligram-level Fe(3)O(4)@SiO(2)-C(18) sorbents with vibration for 10min. By means of a magnet, puerarin adsorbed with Fe(3)O(4)@SiO(2)-C(18) sorbents was easily isolated from the matrix, and desorbed with CAN. No carryover was observed, and the sorbents could be recycled in our study. The method recoveries were obtained from 85.2% to 92.3%. Limits of quantification and limits of detection of 0.1μgmL(-1) and 0.05μgmL(-1), respectively were achieved. The precision was from 8.1 to 13.7% for intra-day measurement, and from 9.4 to 15.2% for inter-day variation. The accuracy ranged from 94.7 to 106.3% for intra-day measurement, and from 93.3 to 107.8% for inter-day measurement. The MSPE method was applied for analysis of puerarin in rat plasma samples. The results indicated that it was convenient and efficient for the determination of puerarin in biosamples.

  1. Objective assessment of olfactory function using functional magnetic resonance imaging.

    PubMed

    Toledano, Adolfo; Borromeo, Susana; Luna, Guillermo; Molina, Elena; Solana, Ana Beatriz; García-Polo, Pablo; Hernández, Juan Antonio; Álvarez-linera, Juan

    2012-01-01

    To show the results of a device that generates automated olfactory stimuli suitable for functional magnetic resonance imaging (fMRI) experiments. Ten normal volunteers, 5 women and 5 men, were studied. The system allows the programming of several sequences, providing the capability to synchronise the onset of odour presentation with acquisition by a trigger signal of the MRI scanner. The olfactometer is a device that allows selection of the odour, the event paradigm, the time of stimuli and the odour concentration. The paradigm used during fMRI scanning consisted of 15-s blocks. The odorant event took 2s with butanol, mint and coffee. We observed olfactory activity in the olfactory bulb, entorhinal cortex (4%), amygdala (2.5%) and temporo-parietal cortex, especially in the areas related to emotional integration. The device has demonstrated its effectiveness in stimulating olfactory areas and its capacity to adapt to fMRI equipment. Copyright © 2010 Elsevier España, S.L. All rights reserved.

  2. Carboxyl-functionalized magnetic microparticle carrier for isolation and identification of DNA in dairy products

    NASA Astrophysics Data System (ADS)

    Horák, Daniel; Rittich, Bohuslav; Španová, Alena

    2007-04-01

    Magnetite nanoparticles about 14 nm in diameter were obtained by chemical coprecipitation of Fe(II) and Fe(III) salts with aqueous ammonia in the presence of poly(ethylene glycol) (PEG). Magnetic poly(glycidyl methacrylate) (PGMA) microspheres about 1 μm in diameter were prepared by dispersion polymerization of GMA in aqueous ethanol in the presence of PEG-coated magnetite nanoparticles. The microspheres were hydrolyzed and carboxyl groups introduced by oxidation with KMnO4. The particles reversibly bound bacterial DNA of Bifidobacterium and Lactobacillus genera in the presence of high concentrations of PEG 6000 and sodium chloride from crude cell lysates of various dairy products (butter milk, cheese, yoghurt, probiotic tablets) or from cell lyophilisates. The presence of Bifidobacterium and Lactobacillus DNA in samples was confirmed by PCR amplification.

  3. Method for preparing hollow metal oxide microsphere

    DOEpatents

    Schmitt, C.R.

    1974-02-12

    Hollow refractory metal oxide microspheres are prepared by impregnating resinous microspheres with a metallic compound, drying the impregnated microspheres, heating the microspheres slowly to carbonize the resin, and igniting the microspheres to remove the carbon and to produce the metal oxide. Zirconium oxide is given as an example. (Official Gazette)

  4. A function of the magnetocaloric effect in a magnetic fluid

    SciTech Connect

    Polunin, V.M.

    1986-01-01

    This paper examines a plane-parallel layer of magnetic fluid (MF) contacting the tmosphere. A relation which determines the density of the fluid with respect to the magnetic field strength is presented in the case of isothermal magnetization. The magnetocaloric effect is discussed which performs the function of one of the possible mechanisms of electromagnitic excitation of elastic vibrations in the MF. Two other mechanisms are discussed: magnetostriction and dipole-dipole.

  5. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    SciTech Connect

    Nan, Alexandrina Bunge, Alexander; Turcu, Rodica

    2015-12-23

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  6. Wave functions of elliptical quantum dots in a magnetic field

    NASA Astrophysics Data System (ADS)

    Zhou, Daming; Lorke, Axel

    2015-03-01

    We use the variational principle to obtain the wave functions of elliptical quantum dots under the influence of an external magnetic field. For the first excited states, whose wave functions have recently been mapped experimentally, we find a simple expression, based on a linear combination of the wave functions in the absence of a magnetic field. The results illustrate how a magnetic field breaks the x-y symmetry and mixes the corresponding eigenstates. The obtained eigenenergies agree well with those obtained by more involved analytical and numerical methods.

  7. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    NASA Astrophysics Data System (ADS)

    Nan, Alexandrina; Bunge, Alexander; Turcu, Rodica

    2015-12-01

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  8. Iron Nanoparticles-Encapsulating Silica Microspheres for Arterial Embolization Hyperthermia

    NASA Astrophysics Data System (ADS)

    Li, Z.; Kawashita, M.

    2011-10-01

    We attempted to prepare α-Fe-encapsulating silica (αFeSi) microspheres by a sol-gel process using tetramethoxysilane (TMOS) in water-in-oil emulsion. The effect of preparation conditions on the structure, magnetic and heating properties of resultant products were investigated. Oil phase consisted of kerosene with 32 wt% of surfactants (sorbitan monooleate / sorbitan monostearate in 3:1 weight ratio). Water phase consisted of TMOS, ethanol (CH2CH3OH), water and iron nitrate (Fe(NO3)3·9H2O) with TMOS / CH2CH3OH/H2O/Fe3+ in 1:7.4:16.2:0.4~1.2 molar ratio. Fe3+-containing silica gel (FeSiG) microspheres 5 to 30 μm in size were successfully obtained by adding the water phase into the oil phase at 60 °C under stirring of 1500 rpm for 100 min. αFeSi microspheres was obtained by heating the FeSiG microspheres at 850°C in argon atmosphere. The obtained αFeSi microspheres have a saturation magnetization (Ms) up to 21 emu g-1 and a coercive force (Hc) of 133 Oe. The in vitro heating generation was evaluated under an alternating current (AC) magnetic field of 300 Oe and 100 kHz.

  9. Ultrasonic alignment of bio-functionalized magnetic beads and live cells in PDMS micro-fluidic channel.

    PubMed

    Islam, Afroja T; Siddique, Ariful H; Ramulu, T S; Reddy, Venu; Eu, Young-Jae; Cho, Seung Hyun; Kim, CheolGi

    2012-12-01

    In this work, we demonstrated the alignment of polystyrene latex microspheres (diameter of 1 ~45 μm), bio-functionalized superparamagnetic beads (diameter 2.8 μm), and live cells (average diameter 1 ~2 μm) using an ultrasonic standing wave (USW) in a PDMS microfluidic channel (330 μm width) attached on a Si substrate for bio-medical applications. To generate a standing wave inside the channel, ultrasound of 2.25 MHz resonance frequency (for the channel width) was applied by two ultrasound transducers installed at both sides of the channel which caused the radiation force to concentrate the micro-particles at the single pressure nodal plane of USW. By increasing the frequency to the next resonance condition of the channel, the particles were concentrated in dual nodal planes. Migration time of the micro-particles towards the single nodal plane was recorded as 108 s, 17 s, and 115 s for polystyrene particles of 2 μm diameter, bio-functionalized magnetic beads, and live cells, respectively. These successful alignments of the bio-functionalized magnetic beads along the desired part of the channel can enhance the performance of a sensor which is applicable for the bio-hybrid system and the alignment of live cells without any damage can be used for sample pre-treatment for the application of lab-on-a-chip type bioassays.

  10. Morphological and functional state of the heart during magnetic storm.

    PubMed

    Chibisov, S M; Breus, T K; Illarionova, T S

    2001-12-01

    Magnetic storm modulates morphological and functional state of the heart and the related systems. Changes in cardiomyocyte ultrastructure induced by changes in geomagnetic activity were studied in experiments on rabbits. We describe a possible mechanism underlying changes in cardiac activity in intact animals induced by geomagnetic perturbations. The most pronounced alterations of cardiomyocyte ultrastructure were observed during the major phase of magnetic storm.

  11. Removal of uranium and fluorine from wastewater by double-functional microsphere adsorbent of SA/CMC loaded with calcium and aluminum

    NASA Astrophysics Data System (ADS)

    Wu, Liping; Lin, Xiaoyan; Zhou, Xingbao; Luo, Xuegang

    2016-10-01

    A novel dual functional microsphere adsorbent of alginate/carboxymethyl cellulose sodium composite loaded with calcium and aluminum (SA/CMC-Ca-Al) is prepared by an injection device to remove fluoride and uranium, respectively, from fluoro-uranium mixed aqueous solution. Batch experiments are performed at different conditions: pH, temperature, initial concentration and contact time. The results show that the maximum adsorption amount for fluoride is 35.98 mg/g at pH 2.0, 298.15 K concentration 100 mg/L, while that for uranium is 101.76 mg/g at pH 4.0, 298.15 K concentration 100 mg/L. Both of the adsorption process could be well described by Langmuir model. The adsorption kinetic data is fitted well with pseudo-first-order model for uranium and pseudo-second-order model for fluoride. Thermodynamic parameters are also evaluated, indicating that the adsorption of uranium on SA/CMC-Ca-Al is a spontaneous and exothermic process, while the removal of fluoride is non-spontaneous and endothermic process. The mechanism of modification and adsorption process on SA/CMC-Ca-Al is characterized by FT-IR, SEM, EDX and XPS. The results show that Ca (II) and Al (III) are loaded on SA/CMC through ion-exchange of sodium of SA/CMC. The coordination reaction and ion-exchange happen during the adsorption process between SA/CMC-Ca-Al and uranium, fluoride. Results suggest that the SA/CMC-Ca-Al adsorbent has a great potential in removing uranium and fluoride from aqueous solution.

  12. Doped zinc oxide microspheres

    DOEpatents

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  13. Doped zinc oxide microspheres

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-12-14

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  14. Microsphere insulation systems

    NASA Technical Reports Server (NTRS)

    Allen, Mark S. (Inventor); Willen, Gary S. (Inventor); Mohling, Robert A. (Inventor)

    2005-01-01

    A new insulation system is provided that contains microspheres. This insulation system can be used to provide insulated panels and clamshells, and to insulate annular spaces around objects used to transfer, store, or transport cryogens and other temperature-sensitive materials. This insulation system provides better performance with reduced maintenance than current insulation systems.

  15. Polyvinyl pyridine microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1980-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  16. Polyvinyl pyridine microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1979-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  17. Fusion microsphere targets

    SciTech Connect

    Koo, J.C.

    1980-07-28

    It was shown that a microsphere within the structure limitations is hydrodynamically stable. To insure its perfect formation, the initial chemical compositions must have a blowing capability, more important, the resultant liquid compositions must also have sufficient surface tension and low viscosity.

  18. Renal relevant radiology: renal functional magnetic resonance imaging.

    PubMed

    Ebrahimi, Behzad; Textor, Stephen C; Lerman, Lilach O

    2014-02-01

    Because of its noninvasive nature and provision of quantitative measures of a wide variety of physiologic parameters, functional magnetic resonance imaging (MRI) shows great potential for research and clinical applications. Over the past decade, application of functional MRI extended beyond detection of cerebral activity, and techniques for abdominal functional MRI evolved. Assessment of renal perfusion, glomerular filtration, interstitial diffusion, and parenchymal oxygenation turned this modality into an essential research and potentially diagnostic tool. Variations in many renal physiologic markers can be detected using functional MRI before morphologic changes become evident in anatomic magnetic resonance images. Moreover, the framework of functional MRI opened a window of opportunity to develop novel pathophysiologic markers. This article reviews applications of some well validated functional MRI techniques, including perfusion, diffusion-weighted imaging, and blood oxygen level-dependent MRI, as well as some emerging new techniques such as magnetic resonance elastography, which might evolve into clinically useful tools.

  19. Magnetic response functions in actinide compounds

    SciTech Connect

    Lander, G.H.

    1986-01-01

    A brief review is given of neutron inelastic scattering experiments on actinide (5f) systems. Only a few compounds exhibit sharp crystal-field levels so that analogies with 4f compounds are rarely straight forward. In the systems that order magnetically, we do find well-defined magnetic excitations, although in many cases the strong interaction with the conduction electrons gives rise to overdamped modes. Finally, in the strongly enhanced paramagnets and heavy-fermion systems the response is essentially featureless in ..-->..Q space and can be characterized by a single Lorentzian with full-width at half-maximum of GAMMA. Attempts to relate this quantity GAMMA to other physical properties, particularly the coefficient of the electronic specific heat ..gamma.., have not been too successful. 22 refs., 5 figs.

  20. Controlling transport and chemical functionality of magnetic nanoparticles.

    PubMed

    Latham, Andrew H; Williams, Mary Elizabeth

    2008-03-01

    A wide range of metal, magnetic, semiconductor, and polymer nanoparticles with tunable sizes and properties can be synthesized by wet-chemical techniques. Magnetic nanoparticles are particularly attractive because their inherent superparamagnetic properties make them desirable for medical imaging, magnetic field assisted transport, and separations and analyses. With such applications on the horizon, synthetic routes for quickly and reliably rendering magnetic nanoparticle surfaces chemically functional have become an increasingly important focus. This Account describes common synthetic routes for making and functionalizing magnetic nanoparticles and discusses initial applications in magnetic field induced separations. The most widely studied magnetic nanoparticles are iron oxide (Fe2O3 and Fe3O4), cobalt ferrite (CoFe 2O4), iron platinum (FePt), and manganese ferrite (MnFe 2O4), although others have been investigated. Magnetic nanoparticles are typically prepared under either high-temperature organic phase or aqueous conditions, producing particles with surfaces that are stabilized by attached surfactants or associated ions. Although it requires more specialized glassware, high-temperature routes are generally preferred when a high degree of stability and low particle size dispersity is desired. Particles can be further modified with a secondary metal or polymer to create core-shell structures. The outer shells function as protective layers for the inner metal cores and alter the surface chemistry to enable postsynthetic modification of the surfactant chemistry. Efforts by our group as well as others have centered on pathways to yield nanoparticles with surfaces that are both easily functionalized and tunable in terms of the number and variety of attached species. Ligand place-exchange reactions have been shown quite successful for exchanging silanes, acids, thiols, and dopamine ligands onto the surfaces of some magnetic particles. Poly(ethylene oxide

  1. Magnetic Resonance, Functional (fMRI) -- Brain

    MedlinePlus

    ... thought, speech, movement and sensation, which is called brain mapping. help assess the effects of stroke, trauma or degenerative disease (such as Alzheimer's) on brain function. monitor the growth and function of brain ...

  2. Enhanced autonomic shutdown of Li-ion batteries by polydopamine coated polyethylene microspheres

    DOE PAGES

    Baginska, Marta; Blaiszik, Benjamin J.; Rajh, Tijana; ...

    2014-07-17

    Thermally triggered autonomic shutdown of a Lithium-ion (Li-ion) battery is demonstrated using polydopamine (PDA)-coated polyethylene microspheres applied onto a battery anode. The microspheres are dispersed in a buffered 10 mM dopamine salt solution and the pH is raised to initiate the polymerization and coat the microspheres. Coated microspheres are then mixed with an aqueous binder, applied onto a battery anode surface, dried, and incorporated into Li-ion coin cells. FTIR and Raman spectroscopy are used to verify the presence of the polydopamine on the surface of the microspheres. Scanning electron microscopy is used to examine microsphere surface morphology and resulting anodemore » coating quality. Charge and discharge capacity, as well as impedance, are measured for Li-ion coin cells as a function of microsphere content. Autonomous shutdown is achieved by applying 1.7 mg cm–2 of PDA-coated microspheres to the electrode. Furthermore, the PDA coating significantly reduces the mass of microspheres for effective shutdown compared to our prior work with uncoated microspheres.« less

  3. Enhanced autonomic shutdown of Li-ion batteries by polydopamine coated polyethylene microspheres

    NASA Astrophysics Data System (ADS)

    Baginska, Marta; Blaiszik, Benjamin J.; Rajh, Tijana; Sottos, Nancy R.; White, Scott R.

    2014-12-01

    Thermally triggered autonomic shutdown of a Lithium-ion (Li-ion) battery is demonstrated using polydopamine (PDA)-coated polyethylene microspheres applied onto a battery anode. The microspheres are dispersed in a buffered 10 mM dopamine salt solution and the pH is raised to initiate the polymerization and coat the microspheres. Coated microspheres are then mixed with an aqueous binder, applied onto a battery anode surface, dried, and incorporated into Li-ion coin cells. FTIR and Raman spectroscopy are used to verify the presence of the polydopamine on the surface of the microspheres. Scanning electron microscopy is used to examine microsphere surface morphology and resulting anode coating quality. Charge and discharge capacity, as well as impedance, are measured for Li-ion coin cells as a function of microsphere content. Autonomous shutdown is achieved by applying 1.7 mg cm-2 of PDA-coated microspheres to the electrode. The PDA coating significantly reduces the mass of microspheres for effective shutdown compared to our prior work with uncoated microspheres.

  4. Enhanced autonomic shutdown of Li-ion batteries by polydopamine coated polyethylene microspheres

    SciTech Connect

    Baginska, Marta; Blaiszik, Benjamin J.; Rajh, Tijana; Sottos, Nancy R.; White, Scott R.

    2014-07-17

    Thermally triggered autonomic shutdown of a Lithium-ion (Li-ion) battery is demonstrated using polydopamine (PDA)-coated polyethylene microspheres applied onto a battery anode. The microspheres are dispersed in a buffered 10 mM dopamine salt solution and the pH is raised to initiate the polymerization and coat the microspheres. Coated microspheres are then mixed with an aqueous binder, applied onto a battery anode surface, dried, and incorporated into Li-ion coin cells. FTIR and Raman spectroscopy are used to verify the presence of the polydopamine on the surface of the microspheres. Scanning electron microscopy is used to examine microsphere surface morphology and resulting anode coating quality. Charge and discharge capacity, as well as impedance, are measured for Li-ion coin cells as a function of microsphere content. Autonomous shutdown is achieved by applying 1.7 mg cm–2 of PDA-coated microspheres to the electrode. Furthermore, the PDA coating significantly reduces the mass of microspheres for effective shutdown compared to our prior work with uncoated microspheres.

  5. Familial Essential Tremor Studied With Functional Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Hernandez, A.; Salgado, P.; Gil, A.; Barrios, F. A.

    2003-09-01

    Functional Magnetic Resonance Imaging has become an important analytical tool to study neurodegenerative diseases. We applied the EPI-BOLD functional Magnetic Resonance Imaging technique to acquire functional images of patients with familial essential tremor (FET) disorder and healthy control volunteers, during a motor task activity. Functional and anatomic images were used to produce the brain activation maps of the patients and volunteers. These functional maps of the primary somatosensorial and motor cortexes of patients and control subjects were compared for functional differences per subject. The averaged functional brain images of eight of each case were acquired were, it can be clearly observed the differences in active zones. The results presented in this work show that there are differences in the functional maps during motor task activation between control subjects and FET patients suggesting a cerebral functional reorganization that can be mapped with BOLD-fMRI.

  6. Polymeric microspheres as protein transduction reagents.

    PubMed

    Nagel, David; Behrendt, Jonathan M; Chimonides, Gwen F; Torr, Elizabeth E; Devitt, Andrew; Sutherland, Andrew J; Hine, Anna V

    2014-06-01

    Discovering the function of an unknown protein, particularly one with neither structural nor functional correlates, is a daunting task. Interaction analyses determine binding partners, whereas DNA transfection, either transient or stable, leads to intracellular expression, though not necessarily at physiologically relevant levels. In theory, direct intracellular protein delivery (protein transduction) provides a conceptually simpler alternative, but in practice the approach is problematic. Domains such as HIV TAT protein are valuable, but their effectiveness is protein specific. Similarly, the delivery of intact proteins via endocytic pathways (e.g. using liposomes) is problematic for functional analysis because of the potential for protein degradation in the endosomes/lysosomes. Consequently, recent reports that microspheres can deliver bio-cargoes into cells via a non-endocytic, energy-independent pathway offer an exciting and promising alternative for in vitro delivery of functional protein. In order for such promise to be fully exploited, microspheres are required that (i) are stably linked to proteins, (ii) can deliver those proteins with good efficiency, (iii) release functional protein once inside the cells, and (iv) permit concomitant tracking. Herein, we report the application of microspheres to successfully address all of these criteria simultaneously, for the first time. After cellular uptake, protein release was autocatalyzed by the reducing cytoplasmic environment. Outside of cells, the covalent microsphere-protein linkage was stable for ≥90 h at 37 °C. Using conservative methods of estimation, 74.3% ± 5.6% of cells were shown to take up these microspheres after 24 h of incubation, with the whole process of delivery and intracellular protein release occurring within 36 h. Intended for in vitro functional protein research, this approach will enable study of the consequences of protein delivery at physiologically relevant levels, without recourse to

  7. A novel synthesis of polyacrolein microspheres and their application for cell labeling and cell separation.

    PubMed

    Margel, S; Beitler, U; Ofarim, M

    1981-01-01

    A novel method for the synthesis of polyacrolein microspheres with fluorescent or magnetic properties is described. These microspheres carry reactive aldehyde groups on their surface, which are used for covalent binding of various proteins at physiological pH. Polyacrolein microspheres may be used as a simple tool for cell labeling and cell separation. The feasibility of specific labeling of fresh human red blood cells and of the separation of human red blood cells from turkey red blood cells by means of a magnetic field is discussed.

  8. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    PubMed Central

    2008-01-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed. PMID:21749733

  9. Porous microsphere and its applications

    PubMed Central

    Cai, Yunpeng; Chen, Yinghui; Hong, Xiaoyun; Liu, Zhenguo; Yuan, Weien

    2013-01-01

    Porous microspheres have drawn great attention in the last two decades for their potential applications in many fields, such as carriers for drugs, absorption and desorption of substances, pulmonary drug delivery, and tissue regeneration. The application of porous microspheres has become a feasible way to address existing problems. In this essay, we give a brief introduction of the porous microsphere, its characteristics, preparation methods, applications, and a brief summary of existing problems and research tendencies. PMID:23515359

  10. Composition and structure of calcium aluminosilicate microspheres

    NASA Astrophysics Data System (ADS)

    Sharonova, O. M.; Oreshkina, N. A.; Zhizhaev, A. M.

    2017-06-01

    The composition was studied of calcium aluminosilicate microspheres of three morphological types in high-calcium fly ash from combustion of brown coal from the Kansk-Achinsk basin in slag-tap boilers at temperatures from 1400 to 1500°C and sampled in the first field of electrostatic precipitators at the Krasnoyarsk Cogeneration Power Station no. 2 (TETs-2). Gross compositions and the composition of local areas were determined using a scanning electron microscopy technique and an energy-dispersive analysis with full mapping of globules. With a high content of basic oxides O ox (68 to 79 wt %) and a low content of acid oxides K ox (21 to 31 wt %), type 1 microspheres are formed. They consist of heterogeneous areas having a porous structure and crystalline components in which the content of CaO, SiO2, or Al2O3 differs by two to three times and the content of MgO differs by seven times. With a lower content of O ox (55 to 63 wt %) and an elevated content of K ox (37 to 45 wt %), type 2 microspheres are formed. They are more homogeneous in the composition and structure and consist of similar crystalline components. Having a close content of O ox (46 to 53 wt %) and K ox (47 to 54 wt %), type 3 microspheres, which are a dense matter consisting of amorphous substance with submicron- and nanostructure of crystalline components, are formed. The basic precursor in formation of high-calcium aluminosilicate microspheres is calcium from the organomineral matter of coals with various contribution of Mg, Fe, S, or Na from the coal organic matter and Al, Fe, S, or Si in the form of single mineral inclusions in a coal particle. On the basis of the available data, the effect was analyzed of the composition of a CaO-MgO-Al2O3-SiO2-FeO system on the melting and viscous properties of the matter in microspheres and formation of globules of different morphology. The results of this analysis will help to find a correlation with properties of microspheres in their use as functional

  11. Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

    PubMed

    Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

    2016-11-04

    High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (PGMA-EDMA) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized PGMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests

  12. Selective, controllable, and reversible aggregation of polystyrene latex microspheres via DNA hybridization.

    PubMed

    Rogers, Phillip H; Michel, Eric; Bauer, Carl A; Vanderet, Stephen; Hansen, Daniel; Roberts, Bradley K; Calvez, Antoine; Crews, Jackson B; Lau, Kwok O; Wood, Alistair; Pine, David J; Schwartz, Peter V

    2005-06-07

    The directed three-dimensional self-assembly of microstructures and nanostructures through the selective hybridization of DNA is the focus of great interest toward the fabrication of new materials. Single-stranded DNA is covalently attached to polystyrene latex microspheres. Single-stranded DNA can function as a sequence-selective Velcro by only bonding to another strand of DNA that has a complementary sequence. The attachment of the DNA increases the charge stabilization of the microspheres and allows controllable aggregation of microspheres by hybridization of complementary DNA sequences. In a mixture of microspheres derivatized with different sequences of DNA, microspheres with complementary DNA form aggregates, while microspheres with noncomplementary sequences remain suspended. The process is reversible by heating, with a characteristic "aggregate dissociation temperature" that is predictably dependent on salt concentration, and the evolution of aggregate dissociation with temperature is observed with optical microscopy.

  13. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials

    NASA Astrophysics Data System (ADS)

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-02-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  14. Correlation Functions of the Magnetization in Thin Films

    NASA Astrophysics Data System (ADS)

    Rebei, A.; Simionato, M.; Parker, G. J.

    2003-05-01

    We calculate the correlation functions of uniform magnetization in thin ferromagnetic films for small deviations from equilibrium, by using a functional formalism. To take account of dissipation and fluctuations consistently, the magnetization is coupled to a bosonic heat bath. The correlation functions show strong dependence on the nature of the coupling between the bath and the system. Depending on what coupling we choose, we show how the recent results $(\\text{J. Appl. Phys. 90, 5768 (2001); Phys. Rev. B 65, 172417 (2002)}) $ obtained by macroscopic methods can be related to the microscopic treatment adopted here.

  15. A direct technique for magnetic functionalization of living human cells.

    PubMed

    Dzamukova, Maria R; Zamaleeva, Alsu I; Ishmuchametova, Dilara G; Osin, Yuri N; Kiyasov, Andrey P; Nurgaliev, Danis K; Ilinskaya, Olga N; Fakhrullin, Rawil F

    2011-12-06

    Functionalized living cells are regarded as effective tools in directed cell delivery and tissue engineering. Here we report the facile functionalization of viable isolated HeLa cells with superparamagnetic cationic nanoparticles via a single-step biocompatible process. Nanoparticles are localized on the cellular membranes and do not penetrate into the cytoplasm. The magnetically responsive cells are viable and able to colonize and grow on substrates. Magnetically facilitated microorganization of functionalized cells into viable living clusters is demonstrated. We believe that the technique described here may find a number of potential applications in cell-based therapies and in development of whole-cell biosensors. © 2011 American Chemical Society

  16. Noncollinear magnetism in density functional calculations

    NASA Astrophysics Data System (ADS)

    Peralta, Juan E.; Scuseria, Gustavo E.; Frisch, Michael J.

    2007-03-01

    We generalize the treatment of the electronic spin degrees of freedom in density functional calculations to the case where the spin vector variables employed in the definition of the energy functional can vary in any direction in space. The expression for the generalized exchange-correlation potential matrix elements is derived for general functionals which among their ingredients include the electron density, its gradient and Laplacian, the kinetic energy density, and nonlocal Hartree-Fock-type exchange. We present calculations on planar Cr clusters that exhibit ground states with noncollinear spin densities due to geometrically frustrated antiferromagnetic interactions.

  17. Magnetization patterns in ferromagnetic nanoelements as functions of complex variable.

    PubMed

    Metlov, Konstantin L

    2010-09-03

    The assumption of a certain hierarchy of soft ferromagnet energy terms, realized in small enough flat nanoelements, allows us to obtain explicit expressions for their magnetization distributions. By minimizing the energy terms sequentially, from the most to the least important, magnetization distributions are expressed as solutions of the Riemann-Hilbert boundary value problem for a function of complex variable. A number of free parameters, corresponding to positions of vortices and antivortices, still remain in the expression. Thus, the presented approach is a factory of realistic Ritz functions for analytical (or numerical) micromagnetic calculations. Examples are given for multivortex magnetization distributions in a circular cylinder, and for two-dimensional domain walls in thin magnetic strips.

  18. Functionalization of polydopamine coated magnetic nanoparticles with biological entities

    NASA Astrophysics Data System (ADS)

    Mǎgeruşan, Lidia; Mrówczyński, Radosław; Turcu, Rodica

    2015-12-01

    New hybrid materials, obtained through introduction of cysteine, lysine and folic acid as biological entities into polydopamine-coated magnetite nanoparticles, are reported. The syntheses are straight forward and various methods were applied for structural and morphological characterization of the resulting nanoparticles. XPS proved a very powerful tool for surface chemical analysis and it evidences the functionalization of polydopamine coated magnetite nanoparticles. The superparamagnetic behavior and the high values of saturation magnetization recommend all products for further application where magnetism is important for targeting, separation, or heating by alternative magnetic fields.

  19. Poly(ethylene glycol)-poly(L-lactide) diblock copolymer prevents aggregation of poly(L-lactide) microspheres during ethylene oxide gas sterilization.

    PubMed

    Choi, Y; Kim, S Y; Moon, M H; Kim, S H; Lee, K S; Byun, Y

    2001-05-01

    Sterilization procedure is one of the most important obstacles in the clinical applications of biodegradable microspheres. The microspheres prepared with poly(alpha-hydroxy acid) were severely aggregated during ethylene oxide (EO) gas sterilization, and could not be used in clinical applications. In this study, the effects of EO gas sterilization on the poly(L-lactide) (PLLA) microspheres were analyzed by nuclear magnetic resonance spectroscopy (1H-NMR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), scanning electron microscope (SEM) and size fractionation. The aggregation between the microspheres might be stimulated by high mobility of amorphous regions of PLLA on the microsphere surfaces since both water vapor and gas mixture can reduce glass transition temperature (Tg) of PLLA below the sterilization temperature. During EO gas sterilization, there were no changes in the molecular structure and the molecular weight of PLLA in microspheres, but there were changes in the crystallinity of PLLA in microspheres. In this study, poly(L-lactide)-poly(ethylene glycol) diblock copolymers (PLE) were blended with PLLA homopolymers in various ratios to design the microsphere suitable for EO gas sterilization. Aggregation of PLLA microspheres was markedly prevented when more than 4wt% of PLE was blended in the microspheres. This inhibition effect on aggregation may be due to the increased initial crystallinity of the microspheres, which help to maintain the microsphere morphology during EO gas sterilization.

  20. Inherently fluorescent polystyrene microspheres for coating, sensing and cellular imaging.

    PubMed

    Qu, Jian-Bo; Xu, Yu-Liang; Liu, Yu; Wang, Yanan; Sui, Yuanhong; Liu, Jian-Guo; Wang, Xiaojuan

    2017-04-01

    Commercially available polystyrene (PS) fluorescent microspheres are widely used in biological field for tracing, in vivo imaging and calibration of flow cytometry, among other applications. However, these particles do suffer from some drawbacks such as the leakage and photobleaching of organic dyes within them. In the present study, inherently fluorescent properties of PS based microspheres have been explored for the first time. Here we find that a simple chloromethylation reaction endows the polystyrene particles with inherent fluorescence without any subsequent conjugation of an external fluorophore. A possible mechanism for fluorescence is elucidated by synthesizing and investigating p-ethylbenzyl chloride, a compound with similar structure. Significantly, no photobleaching or leaking issues were observed owing to the stable structure of the microspheres. Chloromethylated PS (CMPS) microspheres can keep their perpetual blue fluorescence even in dry powder state making them attractive as a potential coating material. Furthermore, the chloromethyl groups on CMPS microspheres make them very convenient for further functionalization. Poly(ethylene glycol) (PEG) grafted microspheres showed good biocompatibility and negligible cytotoxicity, and could be used to image intracellular Fe(3+) due to the selective fluorescence quenching effect of aqueous Fe(3+) in cytoplasm.

  1. Electron Cloud Trapping in Recycler Combined Function Dipole Magnets

    SciTech Connect

    Antipov, Sergey A.; Nagaitsev, S.

    2016-10-04

    Electron cloud can lead to a fast instability in intense proton and positron beams in circular accelerators. In the Fermilab Recycler the electron cloud is confined within its combined function magnets. We show that the field of combined function magnets traps the electron cloud, present the results of analytical estimates of trapping, and compare them to numerical simulations of electron cloud formation. The electron cloud is located at the beam center and up to 1% of the particles can be trapped by the magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multiturn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The multi-turn build-up can be stopped by injection of a clearing bunch of 1010 p at any position in the ring.

  2. Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3-magnetic-microsphere-assisted microwave distillation and simultaneous headspace single-drop microextraction followed by GC-MS.

    PubMed

    Ye, Qing

    2013-06-01

    In this work, microwave distillation assisted by Fe2 O3 magnetic microspheres (FMMS) and headspace single-drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs.

  3. SEVEN TOPICS IN FUNCTIONAL MAGNETIC RESONANCE IMAGING

    PubMed Central

    BANDETTINI, PETER A.

    2010-01-01

    Functional MRI (fMRI) is a non-invasive brain imaging methodology that started in 1991 and allows human brain activation to be imaged at high resolution within only a few minutes. Because it has extremely high sensitivity, is relatively easy to implement, and can be performed on most standard clinical MRI scanners. It continues to grow at an explosive rate throughout the world. Over the years, at any given time, fMRI has been defined by only a handful of major topics that have been the focus of researchers using and developing the methodology. In this review, I attempt to take a snapshot of the field of fMRI as it is in mid-2009 by discussing the seven topics that I feel are most on the minds of fMRI researchers. The topics are, in no particular order or grouping: (1) Clinical impact, (2) Utilization of individual functional maps, (3) fMRI signal interpretation, (4) Pattern effect mapping and decoding, (5) Endogenous oscillations, (6) MRI technology, and (7) Alternative functional contrast mechanisms. Most of these topics are highly interdependent, each advancing as the others advance. While most fMRI involves applications towards clinical or neuroscience questions, all applications are fundamentally dependent on advances in basic methodology as well as advances in our understanding of the relationship between neuronal activity and fMRI signal changes. This review neglects almost completely an in-depth discussion of applications. Rather the discussions are on the methods and interpretation. PMID:19938211

  4. Technical considerations for functional magnetic resonance imaging analysis.

    PubMed

    Conklin, Chris J; Faro, Scott H; Mohamed, Feroze B

    2014-11-01

    Clinical application of functional magnetic resonance imaging (fMRI) based on blood oxygenation level-dependent (BOLD) effect has increased over the past decade because of its ability to map regional blood flow in response to brain stimulation. This mapping is primarily achieved by exploiting the BOLD effect precipitated by changes in the magnetic properties of hemoglobin. BOLD fMRI has utility in neurosurgical planning and mapping neuronal functional connectivity. Conventional echo planar imaging techniques are used to acquire stimulus-driven fMR imaging BOLD data. This article highlights technical aspects of fMRI data analysis to make it more accessible in clinical settings.

  5. Rapid and effective sample cleanup based on graphene oxide-encapsulated core-shell magnetic microspheres for determination of fifteen trace environmental phenols in seafood by liquid chromatography-tandem mass spectrometry.

    PubMed

    Pan, Sheng-Dong; Chen, Xiao-Hong; Shen, Hao-Yu; Li, Xiao-Ping; Cai, Mei-Qiang; Zhao, Yong-Gang; Jin, Mi-Cong

    2016-05-05

    In this study, graphene oxide-encapsulated core-shell magnetic microspheres (GOE-CS-MM) were fabricated by a self-assemble approach between positive charged poly(diallyldimethylammonium) chloride (PDDA)-modified Fe3O4@SiO2 and negative charged GO sheets via electrostatic interaction. The as-prepared GOE-CS-MM was carefully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer analysis (VSM), and X-ray photoelectron spectroscopy (XPS), and was used as a cleanup adsorbent in magnetic solid-phase extraction (MSPE) for determination of 15 trace-level environmental phenols in seafood coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS). The obtained results showed that the GOE-CS-MM exhibited excellent cleanup efficiency and could availably reduce the matrix effect. The cleanup mechanisms were investigated and referred to π-π stacking interaction and hydrogen bond between GOE-CS-MM and impurities in the extracts. Moreover, the extraction and cleanup conditions of GOE-CS-MM toward phenols were optimized in detail. Under the optimized conditions, the limits of detection (LODs) were found to be 0.003-0.06 μg kg(-1), and satisfactory recovery values of 84.8-103.1% were obtained for the tested seafood samples. It was confirmed that the developed method is simple, fast, sensitive, and accurate for the determination of 15 trace environmental phenols in seafood samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Surface modification of cyclomatrix polyphosphazene microsphere by thiol-ene chemistry and lectin recognition

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Zhu, Xue-yan; Gao, Qiao-ling; Fang, Fei; Huang, Xiao-jun

    2016-11-01

    A new synthetic route leading to functional polyphosphazene cyclomatrix microsphere has been developed via thiol-ene click modification. Hexacholorocyclophosphazene (HCCP) was crosslinked with both bisphenol-S and 4,4‧-diallyl bisphenol-S to obtain vinyl polyphosphazene microspheres (VPZM) in order to ensure high crosslinking degree and introduce vinyl moieties. Compared to the microspheres obtained by HCCP and bisphenol-S, the size of VPZM was broadly dispersed from 400 nm to 1.40 μm. Thiol-ene click reactions were carried out to attach functional groups, such as glucosyl, carboxyl, ester and dodecyl groups onto polyphosphazene microspheres, which demonstrated no change in morphology and size after modification. Solid state NMR (SSNMR) and Fourier transform infrared spectoscopy (FT-IR) results showed that the vinyl moieties were introduced in the period of crosslinking and functionalization was also successful via click reactions. Moreover, the microspheres presented a little difference in thermal properties after modification. Concanavalin A (Con-A) fluorescent adsorption was also observed for glucosyl microspheres. Thus, the thiol-ene modified polyphosphazene microspheres displayed chemical flexibility in post-functionalization. These microspheres can be potentially applicated in enzyme immobilization, protein adsorption and chromatographic separation.

  7. Surface functionalized biocompatible magnetic nanospheres for cancer hyperthermia.

    SciTech Connect

    Liu, X.; Novosad, V.; Rozhkova, E. A.; Chen, H.; Yefremenko, V.; Pearson, J.; Torno, M.; Bader, S. D.; Rosengart, A. J.; Univ. Chicago Pritzker School of Medicine

    2007-06-01

    We report a simplified single emulsion (oil-in-water) solvent evaporation protocol to synthesize surface functionalized biocompatible magnetic nanospheres by using highly concentrated hydrophobic magnetite (gel) and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol-maleimide) (PLA-PEG-maleimide) (10:1 by mass) polymers. The as-synthesized particles are approximately spherical with an average diameter of 360-370 nm with polydispersity index of 0.12-0.18, are surface-functionalized with maleimide groups, and have saturation magnetization values of 25-40 emu/g. The efficiency of the heating induced by 400-kHz oscillating magnetic fields is compared for two samples with different magnetite loadings. Results show that these nanospheres have the potential to provide an efficient cancer-targeted hyperthermia.

  8. Peptide-functionalized magnetic nanoparticles for cancer therapy applications

    NASA Astrophysics Data System (ADS)

    Hauser, Anastasia Kruse

    Lung cancer is one of the leading causes of cancer deaths in the United States. Radiation and chemotherapy are conventional treatments, but they result in serious side effects and the probability of tumor recurrence remains high. Therefore, there is an increasing need to enhance the efficacy of conventional treatments. Magnetic nanoparticles have been previously studied for a variety of applications such as magnetic resonance imaging contrast agents, anemia treatment, magnetic cell sorting and magnetically mediated hyperthermia (MMH). In this work, dextran coated iron oxide nanoparticles were developed and functionalized with peptides to target the nanoparticles to either the extracellular matrix (ECM) of tumor tissue or to localize the nanoparticles in subcellular regions after cell uptake. The magnetic nanoparticles were utilized for a variety of applications. First, heating properties of the nanoparticles were utilized to administer hyperthermia treatments combined with chemotherapy. The nanoparticles were functionalized with peptides to target fibrinogen in the ECM and extensively characterized for their physicochemical properties, and MMH combined with chemotherapy was able to enhance the toxicity of chemotherapy. The second application of the nanoparticles was magnetically mediated energy delivery. This treatment does not result in a bulk temperature rise upon actuation of the nanoparticles by an alternating magnetic field (AMF) but rather results in intracellular damage via friction from Brownian rotation or nanoscale heating effects from Neel relaxations. The nanoparticles were functionalized with a cell penetrating peptide to facilitate cell uptake and lysosomal escape. The intracellular effects of the internalized nanoparticles alone and with activation by an AMF were evaluated. Iron concentrations in vivo are highly regulated as excess iron can catalyze the formation of the hydroxyl radical through Fenton chemistry. Although often a concern of using iron

  9. Chalcogenide glass microsphere laser.

    PubMed

    Elliott, Gregor R; Murugan, G Senthil; Wilkinson, James S; Zervas, Michalis N; Hewak, Daniel W

    2010-12-06

    Laser action has been demonstrated in chalcogenide glass microsphere. A sub millimeter neodymium-doped gallium lanthanum sulphide glass sphere was pumped at 808 nm with a laser diode and single and multimode laser action demonstrated at wavelengths between 1075 and 1086 nm. The gallium lanthanum sulphide family of glass offer higher thermal stability compared to other chalcogenide glasses, and this, along with an optimized Q-factor for the microcavity allowed laser action to be achieved. When varying the pump power, changes in the output spectrum suggest nonlinear and/or thermal effects have a strong effect on laser action.

  10. Photonic crystal microspheres

    NASA Astrophysics Data System (ADS)

    Zhokhov, A. A.; Masalov, V. M.; Sukhinina, N. S.; Matveev, D. V.; Dolganov, P. V.; Dolganov, V. K.; Emelchenko, G. A.

    2015-11-01

    Spherical samples of photonic crystals formed by colloidal SiO2 nanoparticles were synthesized. Synthesis of microspheres from 160 nm, 200 nm and 430 nm diameter colloidal nanoparticles was performed over a wide size range, from 5 μm to 50 μm. The mechanism of formation of void microparticles exceeding 50 μm is discussed. The spectral measurements verified the association of the spectra with the peaks of selective reflection from the cubic lattice planes. The microparticle morphology is characterized by scanning electron microscopy (SEM).

  11. Functional Connectivity Magnetic Resonance Imaging Classification of Autism

    ERIC Educational Resources Information Center

    Anderson, Jeffrey S.; Nielsen, Jared A.; Froehlich, Alyson L.; DuBray, Molly B.; Druzgal, T. Jason; Cariello, Annahir N.; Cooperrider, Jason R.; Zielinski, Brandon A.; Ravichandran, Caitlin; Fletcher, P. Thomas; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

    2011-01-01

    Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear…

  12. Functional Connectivity Magnetic Resonance Imaging Classification of Autism

    ERIC Educational Resources Information Center

    Anderson, Jeffrey S.; Nielsen, Jared A.; Froehlich, Alyson L.; DuBray, Molly B.; Druzgal, T. Jason; Cariello, Annahir N.; Cooperrider, Jason R.; Zielinski, Brandon A.; Ravichandran, Caitlin; Fletcher, P. Thomas; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

    2011-01-01

    Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear…

  13. Room temperature organic magnets derived from sp3 functionalized graphene

    NASA Astrophysics Data System (ADS)

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B.; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-02-01

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via -OH functionalization.

  14. Room temperature organic magnets derived from sp(3) functionalized graphene.

    PubMed

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-02-20

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp(3) coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp(2)-conjugated diradical motifs embedded in an sp(3) matrix and superexchange interactions via -OH functionalization.

  15. Room temperature organic magnets derived from sp3 functionalized graphene

    PubMed Central

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B.; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-01-01

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via –OH functionalization. PMID:28216636

  16. Functional orthopedic magnetic appliance (FOMA) II--modus operandi.

    PubMed

    Vardimon, A D; Stutzmann, J J; Graber, T M; Voss, L R; Petrovic, A G

    1989-05-01

    A new functional appliance (FA) to correct Class II dentoskeletal malocclusions is introduced. The functional orthopedic magnetic appliance (FOMA) II uses upper and lower attracting magnetic means (Nd2Fe14B) to constrain the lower jaw in an advanced sagittal posture. In vitro, a special gauge transducer measured the magnetic attractive path and forces. In vivo, 13 prepubertal female Macaca fascicularis monkeys received facial implants and were treated for 4 months with the following appliances: conventional FA (four subjects), FOMA II (five subjects), a combined FOMA II + FA (two subjects), and sham (control) appliance (two subjects). The in vitro results showed the following: vertico-sagitally displaced upper and lower magnets attracted ultimately along an oblique line with a terminal horizonal slide to become fully superimposed; the functional performance improved when the magnetic interface acted as a magnetic inclined plane; and the magnetic force was able to guide and constrain the mandible toward the constructive protrusive closure position (CPCP) (1.2 mm, F = 570 gm) from levels below the habitual rest position (3 mm, F = 219 gm) and the electromyographic (EMG) relaxed position (8.5 mm, F = 45 gm). The in vivo results demonstrated the following: functional performance increased in FOMA II (22%) and in the combined FOMA II + FA (28%) over the conventional FA; mandibular length increased significantly in the treated animals (means = 2.83 +/- 0.70 mm) over the control animals (means = 0.43 +/- 0.08 mm); incisor proclination was lower in magnetic appliances (means = 4.57 +/- 1.76 degrees) than in the conventional FA (means = 8.75 +/- 1.85 degrees); mandibular elongation and condylar posterior inclination resulted from posterosuperior endochondral growth (increased cell proliferation and/or hyperplasia of functional chondroblasts) and by bony remodeling of the condylar neck (apposition posterior border, resorption anterior border), respectively; virtually no

  17. Modular scaffolds assembled around living cells using poly(ethylene glycol) microspheres with macroporation via a non-cytotoxic porogen

    PubMed Central

    Scott, Evan A.; Nichols, Michael D.; Kuntz-Willits, Rebecca; Elbert, Donald L.

    2009-01-01

    Modular, bioactive, macroporous scaffolds were formed by crosslinking poly(ethylene glycol) (PEG) microspheres around living cells. Hydrogel microspheres were produced from reactive PEG derivatives in aqueous sodium sulfate solutions without the use of surfactants or copolymers. Microspheres were formed following thermally induced phase separation if the gel point was reached prior to extensive coarsening of the PEG-rich domains. Three types of PEG microspheres with different functionalities were used to form scaffolds. One type of PEG microsphere provided mechanical support, the second type provided controlled delivery of the angiogenesis-promoting molecule, sphingosine 1-phosphate (S1P), and the third type served as a slowly dissolving non-cytotoxic porogen. Scaffolds were formed by centrifuging microspheres in the presence of HepG2 hepatoma cells, resulting in a homogenous distribution of cells. During overnight incubation at 37°C, the microspheres reacted with serum proteins in cell culture medium to stabilize the scaffolds. Within two days in culture, macropores formed due to the dissolution of the porogenic PEG microspheres, without affecting cell viability. Gradients in porosity were produced by varying the buoyancy of the porogenic microspheres. Conjugated RGD cell adhesion peptides and delivery of sphingosine 1-phosphate promoted endothelial cell infiltration through macropores in the scaffolds. The scaffolds presented here differ from previous hydrogel scaffolds in that: 1) cells are not encapsulated in hydrogel, 2) macropores form in the presence of cells, and 3) scaffold properties are controlled by the modular assembly of different microspheres that perform distinct functions. PMID:19607945

  18. Fabrication of novel multihollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via water-in-oil-in-water double emulsions.

    PubMed

    Yang, Song; Liu, Huarong; Zhang, Zhicheng

    2008-09-16

    We herein present a novel and simple synthetic strategy for fabricating multihollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via water-in-oil-in-water double emulsions. Amphipathic magnetite nanoparticles surface-modified with oleic acid act as an oil-soluble emulsifier and sodium dodecyl sulfate acts as a water-soluble surfactant in the system. The final products were thoroughly characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy, which showed the formation of multihollow magnetite/polystyrene nanocomposite microspheres. Preliminary results of magnetic properties of multihollow magnetite/polystyrene microspheres were reported. The effect of the content of amphipathic magnetite nanoparticles on the morphology of nanocomposite microspheres was studied. Furthermore, the mechanism of formation of multihollow magnetic nanocomposite microspheres was also discussed.

  19. Functional magnetic resonance imaging in medicine and physiology

    SciTech Connect

    Moonen, C.T.W.; van Zijl, P.C.M.; Frank, J.A.; Bihan, D.L.; Becker, E.D. )

    1990-10-05

    Magnetic resonance imaging (MRI) is a well-established diagnostic tool that provides detailed information about macroscopic structure and anatomy. Recent advances in MRI allow the noninvasive spatial evaluation of various biophysical and biochemical processes in living systems. Specifically, the motion of water can be measured in processes such as vascular flow, capillary flow, diffusion, and exchange. In addition, the concentrations of various metabolites can be determined for the assessment of regional regulation of metabolism. Examples are given that demonstrate the use of functional MRI for clinical and research purposes. This development adds a new dimension to the application of magnetic resonance to medicine and physiology.

  20. Microsphere based saliva diagnostics

    NASA Astrophysics Data System (ADS)

    Rissin, David M.; DiCesare, Christopher; Hayman, Ryan B.; Blicharz, Timothy M.; Walt, David R.

    2005-11-01

    Saliva presents a minimally invasive alternative medium to blood for performing diagnostics1. Microsphere sensors for ions, small organic molecules, and proteins are currently being developed and optical microarrays containing thousands of these sensors will be used for simultaneous multi-analyte analysis. The fiber bundle platform in use is 1mm in diameter and contains approximately 50,000 individually addressable 3.1μm fibers, each with an etched well capable of housing a single 3.1μm microsphere sensor. Micron-sized bead-based chemistries are produced in house, followed by deposition onto a fiber-optic bundle platform, allowing for multiplexed analysis. The ultimate goal is to develop a universal diagnostic system using saliva as the diagnostic medium. This platform will permit multiplexed analysis of a sample by integrating microfluidics with the optical arrays loaded with sensors capable of detecting relevant biomarkers associated with a wide range of disease states. Disease states that are currently under investigation include end stage renal disease (ESRD) and Sjoegrens Syndrome (SS).

  1. Towards Monodispersed Polymer Microspheres

    NASA Astrophysics Data System (ADS)

    Senuma, Yoshinori; Hilborn, Jons

    1998-03-01

    Uniform polymer microspheres prepared by Spinning Disk Atomization Our spinning disk atomization (SDA) can, relative to other existing techniques, produce micron-sized particles of very narrow size distribution. Around the edge of the disk, small teeth channel the flow into identical droplets that are flung off over the disk rim. These solidify during flight to form spherical particles. Applications for spheres produced by SDA can be found in areas such as adhesives, powder coatings, food, biomedical use, drug delivery systems, etc. We have atomized polyethyleneglycol into very narrowly dispersed microspheres ranging from 50 to 500 =B5m. The aim of this work is to model the droplet formation occurring at the rim of the spinning disk in order to better understand the experimental results. The viscosity contribution in the fluid breakup is qualitatively analyzed and is adapted to the theoretical model to show how it affects the droplet size. We have used the pendant drop model (Ramesh Babu, S. Journal of Colloid and Interface Science 116, 350-372 (1987).) for spinning disk atomization to describe the drop-shape evolution during growth.

  2. Graphene functionalized porous Au-paper based electrochemiluminescence device for detection of DNA using luminescent silver nanoparticles coated calcium carbonate/carboxymethyl chitosan hybrid microspheres as labels.

    PubMed

    Li, Meng; Wang, Yanhu; Zhang, Yan; Yu, Jinghua; Ge, Shenguang; Yan, Mei

    2014-09-15

    In the paper, a simple and sensitive electrochemiluminescence (ECL) DNA sensor based on graphene-modified porous Au-paper working electrode (GR/Au-PWE) and calcium carbonate/carboxymethyl chitosan (CaCO3/CMC) hybrid microspheres @ luminescent silver nanoparticles (AgNPs) composites was developed. The GR/Au-PWE with excellent conductivity was successfully prepared for the immobilization of capture probe. The CaCO3/CMC hybrid microspheres were prepared by the precipitation of calcium carbonate in an aqueous solution containing CMC. The AgNPs was synthesized by thermal reduction of silver ions in glycine matrix, taking advantage of the solid-state matrix to control the nucleation and migration of reduced silver atoms. The CaCO3/CMC@AgNPs composites exhibited 3.6 times higher ECL intensity than the pure AgNPs-labeled reporter DNA. Taking advantage of dual-amplification effects, the paper-based DNA sensor could detect the target DNA quantitatively, in the range of 4.0×10(-17)-5.0×10(-11) M, with a limit of detection as low as 8.5×10(-18) M, and perform excellent selectivity. The simple, low-cost, sensitive device could be easily applied for point-of-care testing, public health and environmental monitoring in remote regions, developing or developed countries. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Fluorescent and colorimetric magnetic microspheres as nanosensors for Hg2+ in aqueous solution prepared by a sol-gel grafting reaction and host-guest interaction

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhang, Yue; Yang, Qingbiao; Sun, Mingda; Fei, Xiaoliang; Song, Yan; Zhang, Yingmu; Li, Yaoxian

    2013-05-01

    Fluorescent sensing TSRh6G-β-cyclodextrin fluorophore/adamantane-modified inclusion complex magnetic nanoparticles (TFIC MNPs) have been synthesized via the cooperation of a host-guest interaction and sol-gel grafting reaction. Powder X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV-visible absorption and emission spectroscopy have been employed to characterize the material. Fluorescence and UV-visible spectra have shown that the resultant multifunctional nanoparticle sensors exhibit selective `turn-on' type fluorescent enhancements and a clear color change from light brown to pink with Hg2+. Owing to a larger surface area and high permeability, TFIC MNPs exhibit remarkable selectivity and sensitivity for Hg2+, and its detection limit measures up to the micromolar level in aqueous solution. Most importantly, magnetic measurements have shown that TFIC magnetic nanoparticles are superparamagnetic and they can be separated and collected easily using a commercial magnet. These results not only solve the limitations in practical sensing applications of nanosensors, but also enable the fabrication of other multifunctional nanostructure-based hybrid nanomaterials.Fluorescent sensing TSRh6G-β-cyclodextrin fluorophore/adamantane-modified inclusion complex magnetic nanoparticles (TFIC MNPs) have been synthesized via the cooperation of a host-guest interaction and sol-gel grafting reaction. Powder X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV-visible absorption and emission spectroscopy have been employed to characterize the material. Fluorescence and UV-visible spectra have shown that the resultant multifunctional nanoparticle sensors exhibit selective `turn-on' type fluorescent enhancements and a clear color change from light brown to pink with Hg2+. Owing to a larger surface area and high permeability, TFIC MNPs exhibit remarkable selectivity and sensitivity for Hg2

  4. Mesenchymal Stem Cell Magnetization: Magnetic Multilayer Microcapsule Uptake, Toxicity, Impact on Functional Properties, and Perspectives for Magnetic Delivery.

    PubMed

    Lepik, Kirill V; Muslimov, Albert R; Timin, Alexander S; Sergeev, Vladislav S; Romanyuk, Dmitry S; Moiseev, Ivan S; Popova, Elena V; Radchenko, Igor L; Vilesov, Alexander D; Galibin, Oleg V; Sukhorukov, Gleb B; Afanasyev, Boris V

    2016-12-01

    Mesenchymal stem cells (MSCs) are widely used in cell therapy due to their convenience, multiline differentiation potential, reproducible protocols, and biological properties. The potential of MSCs to impregnate magnetic microcapsules and their possible influence on cell function and ability to response to magnetic field have been explored. Interestingly, the cells suspended in media show much higher ability in internalization of microcapsules, then MSCs adhere into the surface. There is no significant effect of microcapsules on cell toxicity compared with other cell line-capsule internalization reported in literature. Due to internalization of magnetic capsules by the cells, such cell engineering platform is responsive to external magnetic field, which allows to manipulate MSC migration. Magnetically sorted MSCs are capable to differentiation as confirmed by their conversion to adipogenic and osteogenic cells using standard protocols. There is a minor effect of capsule internalization on cell adhesion, though MSCs are still able to form spheroid made by dozen of thousand MSCs. This work demonstrates the potential of use of microcapsule impregnated MSCs to carry internalized micron-sized vesicles and being navigated with external magnetic signaling. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Exponentially localized Wannier functions in periodic zero flux magnetic fields

    NASA Astrophysics Data System (ADS)

    De Nittis, G.; Lein, M.

    2011-11-01

    In this work, we investigate conditions which ensure the existence of an exponentially localized Wannier basis for a given periodic hamiltonian. We extend previous results [Panati, G., Ann. Henri Poincare 8, 995-1011 (2007), 10.1007/s00023-007-0326-8] to include periodic zero flux magnetic fields which is the setting also investigated by Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. The new notion of magnetic symmetry plays a crucial rôle; to a large class of symmetries for a non-magnetic system, one can associate "magnetic" symmetries of the related magnetic system. Observing that the existence of an exponentially localized Wannier basis is equivalent to the triviality of the so-called Bloch bundle, a rank m hermitian vector bundle over the Brillouin zone, we prove that magnetic time-reversal symmetry is sufficient to ensure the triviality of the Bloch bundle in spatial dimension d = 1, 2, 3. For d = 4, an exponentially localized Wannier basis exists provided that the trace per unit volume of a suitable function of the Fermi projection vanishes. For d > 4 and d ⩽ 2m (stable rank regime) only the exponential localization of a subset of Wannier functions is shown; this improves part of the analysis of Kuchment [J. Phys. A: Math. Theor. 42, 025203 (2009), 10.1088/1751-8113/42/2/025203]. Finally, for d > 4 and d > 2m (unstable rank regime) we show that the mere analysis of Chern classes does not suffice in order to prove triviality and thus exponential localization.

  6. Liraglutide-loaded poly(lactic-co-glycolic acid) microspheres: Preparation and in vivo evaluation.

    PubMed

    Wu, Junzi; Williams, Gareth R; Branford-White, Christopher; Li, Heyu; Li, Yan; Zhu, Li-Min

    2016-09-20

    In this work, we sought to generate sustained-release injectable microspheres loaded with the GLP-1 analogue liraglutide. Using water-in-oil-in-water double emulsion methods, poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with liraglutide were prepared. The microspheres gave sustained drug release over 30days, with cumulative release of up to 90% reached in vitro. The microspheres were further studied in a rat model of diabetes, and their performance compared with a group given daily liraglutide injections. Reduced blood sugar levels were seen in the microsphere treatment groups, with the results being similar to those obtained with conventional injections between 10 and 25days after the commencement of treatment. After 5 and 30days of treatment, the microspheres seem a little slower to act than the injections. The pathology of the rats' spleen, heart, kidney and lungs was probed after the 30-day treatment period, and the results indicated that the microspheres were safe and had beneficial effects on the liver, reducing the occurrence of fatty deposits seen in untreated diabetic rats. Moreover, in terms of liver, renal and cardiac functions, and blood lipid and antioxidant levels, the microspheres were as effective as the injections. The expression of several proteases linked to the metabolism of aliphatic acids and homocysteine was promoted by the microsphere formulations. Inflammatory markers in the microsphere treatment groups were somewhat higher than the injection group, however. The liraglutide/PLGA microspheres prepared in this work are overall shown to be efficacious in a rat model of diabetes, and we thus believe they have strong potential for clinical use.

  7. Fluorescent and colorimetric magnetic microspheres as nanosensors for Hg2+ in aqueous solution prepared by a sol-gel grafting reaction and host-guest interaction.

    PubMed

    Wang, Wei; Zhang, Yue; Yang, Qingbiao; Sun, Mingda; Fei, Xiaoliang; Song, Yan; Zhang, Yingmu; Li, Yaoxian

    2013-06-07

    Fluorescent sensing TSRh6G-β-cyclodextrin fluorophore/adamantane-modified inclusion complex magnetic nanoparticles (TFIC MNPs) have been synthesized via the cooperation of a host-guest interaction and sol-gel grafting reaction. Powder X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV-visible absorption and emission spectroscopy have been employed to characterize the material. Fluorescence and UV-visible spectra have shown that the resultant multifunctional nanoparticle sensors exhibit selective 'turn-on' type fluorescent enhancements and a clear color change from light brown to pink with Hg(2+). Owing to a larger surface area and high permeability, TFIC MNPs exhibit remarkable selectivity and sensitivity for Hg(2+), and its detection limit measures up to the micromolar level in aqueous solution. Most importantly, magnetic measurements have shown that TFIC magnetic nanoparticles are superparamagnetic and they can be separated and collected easily using a commercial magnet. These results not only solve the limitations in practical sensing applications of nanosensors, but also enable the fabrication of other multifunctional nanostructure-based hybrid nanomaterials.

  8. Zero-field magnetic response functions in Landau levels

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Niu, Qian

    2017-07-01

    We present a fresh perspective on the Landau level quantization rule; that is, by successively including zero-field magnetic response functions at zero temperature, such as zero-field magnetization and susceptibility, the Onsager’s rule can be corrected order by order. Such a perspective is further reinterpreted as a quantization of the semiclassical electron density in solids. Our theory not only reproduces Onsager’s rule at zeroth order and the Berry phase and magnetic moment correction at first order but also explains the nature of higher-order corrections in a universal way. In applications, those higher-order corrections are expected to curve the linear relation between the level index and the inverse of the magnetic field, as already observed in experiments. Our theory then provides a way to extract the correct value of Berry phase as well as the magnetic susceptibility at zero temperature from Landau level fan diagrams in experiments. Moreover, it can be used theoretically to calculate Landau levels up to second-order accuracy for realistic models.

  9. Functional orthopedic magnetic appliance (FOMA) III--modus operandi.

    PubMed

    Vardimon, A D; Graber, T M; Voss, L R; Muller, T P

    1990-02-01

    An intraoral intermaxillary appliance has been developed for the treatment of Class III malocclusions that exhibit midface sagittal deficiency with or without mandibular excess. The functional orthopedic magnetic appliance (FOMA) III consists of upper and lower acrylic plates with a permanent magnet incorporated into each plate. The upper magnet is linked to a retraction screw. The upper magnet is retracted periodically (e.g., monthly) to stimulate maxillary advancement and mandibular retardation. The attractive mode neodymium magnets used in this study produced a horizontal force of 98 gm and a vertical force of 371 gm. Six female Macaca fascicularis monkeys were treated with FOMA IIIs. An additional three animals were treated with sham appliances. After 4 months of treatment, the following results were found: the growth pattern of the cranial base (saddle angle) was not altered; midfacial protraction did occur along a recumbent hyperbolic curve with a horizontal maxillary displacement and an anterosuperior premaxillary rotation; the cumulative protraction of the maxillary complex was initiated at the pterygomaxillary fissure with an additional contribution provided by other circummaxillary sutures (zygomaticomaxillary s., transverse s., premaxillary s.); and inhibition of mandibular length was minimal, but a tendency toward a vertical condylar growth pattern was observed. The interaction between sutural and condylar growth sites appeared biphasic, characterized by an immediate and rapid excitation of the circummaxillary sutures followed by a delayed and slow suppression of the condylar cartilage. Long-term animal and clinical FOMA III studies are recommended.

  10. Zero-field magnetic response functions in Landau levels.

    PubMed

    Gao, Yang; Niu, Qian

    2017-07-11

    We present a fresh perspective on the Landau level quantization rule; that is, by successively including zero-field magnetic response functions at zero temperature, such as zero-field magnetization and susceptibility, the Onsager's rule can be corrected order by order. Such a perspective is further reinterpreted as a quantization of the semiclassical electron density in solids. Our theory not only reproduces Onsager's rule at zeroth order and the Berry phase and magnetic moment correction at first order but also explains the nature of higher-order corrections in a universal way. In applications, those higher-order corrections are expected to curve the linear relation between the level index and the inverse of the magnetic field, as already observed in experiments. Our theory then provides a way to extract the correct value of Berry phase as well as the magnetic susceptibility at zero temperature from Landau level fan diagrams in experiments. Moreover, it can be used theoretically to calculate Landau levels up to second-order accuracy for realistic models.

  11. Functionalized magnetic core-shell Fe3O4@SiO2 nanoparticles for sensitive detection and removal of Hg2+

    NASA Astrophysics Data System (ADS)

    Xu, Yaohui; Zhou, Yang; Ma, Wenhui; Wang, Shixing; Li, Shaoyuan

    2013-06-01

    The Fe3O4 nanoparticles [NPs] coated with silica nanoparticles were designed and prepared, the obtained Fe3O4@SiO2 NPs have uniform spherical morphology with a mean diameter of about 22 nm. The inert silica coating on the surface of Fe3O4 NPs not only significantly prevented their aggregation in solution but also improved their chemical stability and provided wider sites for surface modification with organic chemosensors. Subsequently an attempt had been made that the as-synthesized Fe3O4@SiO2 NPs were modified by N-(rhodamine-6G) lactam-ethylenediamine, the functionalized magnetic Fe3O4@SiO2 NPs (Fe3O4@SiO2-Rho) served as a "naked eye" fluorescent sensor to detect Hg2+. The Fe3O4@SiO2-Rho NPs exhibited selective "turn-on" type fluorescent change from colorless to orange when adding to Hg2+. In addition, the adsorption experiments revealed that the Fe3O4@SiO2-Rho NPs had effective removal toward Hg2+. Moreover, the functionalized Fe3O4@SiO2 microspheres displayed superparamagnetic properties, which made it easier to separate the nanocomposites from the liquid phase by adding an external magnetic field. Our efforts provided a potential magnetic nanomaterial for sensitive detection and removal toward Hg2+ simultaneously.

  12. Selective Capture and Quick Detection of Targeting Cells with SERS-Coding Microsphere Suspension Chip.

    PubMed

    Li, Dian; Zhang, Yuting; Li, Ruimin; Guo, Jia; Wang, Changchun; Tang, Chuanbing

    2015-05-13

    Circulating tumor cells (CTCs) captured from blood fluid represent recurrent cancers and metastatic lesions to monitor the situation of cancers. We develop surface-enhanced Raman scattering (SERS)-coding microsphere suspension chip as a new strategy for fast and efficient capture, recovery, and detection of targeting cancer cells. Using HeLa cells as model CTCs, we first utilize folate as a recognition molecule to be immobilized in magnetic composite microspheres for capturing HeLa cells and attaining high capturing efficacy (up to 95%). After capturing cells, the composite microsphere, which utilizes a disulfide bond as crosslinker in the polymer shell and as a spacer for linking folate, can recycle 90% cells within 20 min eluted by glutathion solution. Taking advantage of the SERS with fingerprint features, we characterize captured/recovered cells with the unique signal of report-molecule 4-aminothiophenol through introducing the SERS-coding microsphere suspension chip to CTCs. Finally, the exploratory experiment of sieving cells shows that the magnetic composite microspheres can selectively capture the HeLa cells from samples of mixed cells, indicating that these magnetic composite microspheres have potential in real blood samples for capturing CTCs.

  13. Glass microsphere lubrication

    NASA Technical Reports Server (NTRS)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  14. Functional magnetic resonance imaging in oncology: state of the art.

    PubMed

    Guimaraes, Marcos Duarte; Schuch, Alice; Hochhegger, Bruno; Gross, Jefferson Luiz; Chojniak, Rubens; Marchiori, Edson

    2014-01-01

    In the investigation of tumors with conventional magnetic resonance imaging, both quantitative characteristics, such as size, edema, necrosis, and presence of metastases, and qualitative characteristics, such as contrast enhancement degree, are taken into consideration. However, changes in cell metabolism and tissue physiology which precede morphological changes cannot be detected by the conventional technique. The development of new magnetic resonance imaging techniques has enabled the functional assessment of the structures in order to obtain information on the different physiological processes of the tumor microenvironment, such as oxygenation levels, cellularity and vascularity. The detailed morphological study in association with the new functional imaging techniques allows for an appropriate approach to cancer patients, including the phases of diagnosis, staging, response evaluation and follow-up, with a positive impact on their quality of life and survival rate.

  15. Magnetic anisotropy of metal functionalized phthalocyanine 2D networks

    NASA Astrophysics Data System (ADS)

    Zhu, Guojun; Zhang, Yun; Xiao, Huaping; Cao, Juexian

    2016-06-01

    The magnetic anisotropy of metal including Cr, Mn, Fe, Co, Mo, Tc, Ru, Rh, W, Re, Os, Ir atoms functionalized phthalocyanine networks have been investigated with first-principles calculations. The magnetic moments can be expressed as 8-n μB with n the electronic number of outmost d shell in the transition metals. The huge magnetocrystalline anisotropy energy (MAE) is obtained by torque method. Especially, the MAE of Re functionalized phthalocyanine network is about 20 meV with an easy axis perpendicular to the plane of phthalocyanine network. The MAE is further manipulated by applying the external biaxial strain. It is found that the MAE is linear increasing with the external strain in the range of -2% to 2%. Our results indicate an effective approach to modulate the MAE for practical application.

  16. Functional magnetic resonance imaging in oncology: state of the art*

    PubMed Central

    Guimaraes, Marcos Duarte; Schuch, Alice; Hochhegger, Bruno; Gross, Jefferson Luiz; Chojniak, Rubens; Marchiori, Edson

    2014-01-01

    In the investigation of tumors with conventional magnetic resonance imaging, both quantitative characteristics, such as size, edema, necrosis, and presence of metastases, and qualitative characteristics, such as contrast enhancement degree, are taken into consideration. However, changes in cell metabolism and tissue physiology which precede morphological changes cannot be detected by the conventional technique. The development of new magnetic resonance imaging techniques has enabled the functional assessment of the structures in order to obtain information on the different physiological processes of the tumor microenvironment, such as oxygenation levels, cellularity and vascularity. The detailed morphological study in association with the new functional imaging techniques allows for an appropriate approach to cancer patients, including the phases of diagnosis, staging, response evaluation and follow-up, with a positive impact on their quality of life and survival rate. PMID:25741058

  17. Magnetic resonance imaging based functional imaging in paediatric oncology.

    PubMed

    Manias, Karen A; Gill, Simrandip K; MacPherson, Lesley; Foster, Katharine; Oates, Adam; Peet, Andrew C

    2017-02-01

    Imaging is central to management of solid tumours in children. Conventional magnetic resonance imaging (MRI) is the standard imaging modality for tumours of the central nervous system (CNS) and limbs and is increasingly used in the abdomen. It provides excellent structural detail, but imparts limited information about tumour type, aggressiveness, metastatic potential or early treatment response. MRI based functional imaging techniques, such as magnetic resonance spectroscopy, diffusion and perfusion weighted imaging, probe tissue properties to provide clinically important information about metabolites, structure and blood flow. This review describes the role of and evidence behind these functional imaging techniques in paediatric oncology and implications for integrating them into routine clinical practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Biosensing by WGM Microspherical Resonators

    PubMed Central

    Righini, Giancarlo C.; Soria, Silvia

    2016-01-01

    Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 108–109 lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed. PMID:27322282

  19. Biosensing by WGM Microspherical Resonators.

    PubMed

    Righini, Giancarlo C; Soria, Silvia

    2016-06-17

    Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 10⁸-10⁸ lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed.

  20. Using Functional Magnetic Resonance Imaging to Detect Preserved Function in a Preterm Infant with Brain Injury.

    PubMed

    Herzmann, Charlotte; Zubiaurre-Elorza, Leire; Wild, Conor J; Linke, Annika C; Han, Victor K; Lee, David S C; Cusack, Rhodri

    2017-10-01

    We studied developmental plasticity using functional magnetic resonance imaging (fMRI) in a preterm infant with brain injury on structural MRI. fMRI showed preserved brain function and subsequent neurodevelopment was within the normal range. Multimodal neuroimaging including fMRI can improve understanding of neural plasticity after preterm birth and brain injury. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Coil Design for Functional Magnetic Stimulation of the Inspiratory Muscles

    DTIC Science & Technology

    2001-10-25

    Computer modeling of magnetic coils A computer program FlexPDE , developed by PDE Solution, was used to simulate the induced electric field and nerve...activation function generated in saline solution. FlexPDE is a general solver for the solutions of systems of partial differential equations such...everywhere else. Solving a problem with FlexPDE required physical description of the problem. To describe the problem, it was necessary to define the

  2. Establishment and implications of a characterization method for magnetic nanoparticle using cell tracking velocimetry and magnetic susceptibility modified solutions.

    PubMed

    Zhang, Huading; Moore, Lee R; Zborowski, Maciej; Williams, P Stephen; Margel, Shlomo; Chalmers, Jeffrey J

    2005-04-01

    Magnetic micro and nanoparticles conjugated to affinity labels have become a significant, commercial reagent. It has been demonstrated that the performance of cell separation systems using magnetic labels is a function of the magnitude of the magnetic force that can be generated through labeling. This magnetic force is proportional to the number of magnetic particles bound to the cell, the magnetic energy gradient, and the particle-field interaction parameter. This particle-field interaction parameter, which is the product of the relative volumetric, magnetic susceptibility and the volume of the micro or nanoparticle, is a fundamental parameter which can be used to characterize the magnetic particles. An experimental technique is presented which measures the volumetric magnetic susceptibility of particles through the use of susceptibility modified solutions and an experimental instrument, Cell Tracking Velocimetry, CTV. Experimental studies were conducted on polystyrene microspheres alone and those bound to four different magnetic nanoparticles. The experimentally determined values of the magnetic susceptibility of the polystyrene microspheres are consistent with values found from literature. Consequently, magnetic susceptibility measurements of these polystyrene microspheres bound with the magnetic nanoparticles combined with particle size measurements using commercial dynamic light scattering instrument allowed estimates of the particle-field interaction parameter to be made for four commercial, magnetic nanoparticles. The value found for MACS beads is close to what is reported from an independent study. The values for MACS beads and Imag beads are found to agree with what is observed from experiments. Finally, an experimental demonstration of the impact that differences in this field interaction parameter has on the labeling of human lymphocytes is presented.

  3. Systematic analysis of functional and structural changes after coronary microembolization: a cardiac magnetic resonance imaging study.

    PubMed

    Breuckmann, Frank; Nassenstein, Kai; Bucher, Christina; Konietzka, Ina; Kaiser, Gernot; Konorza, Thomas; Naber, Christoph; Skyschally, Andreas; Gres, Petra; Heusch, Gerd; Erbel, Raimund; Barkhausen, Jörg

    2009-02-01

    Our study aimed to detect the morphological und functional effects of coronary microembolization (ME) in vivo by cardiac magnetic resonance (CMR) imaging in an established experimental animal model. Post-mortem morphological alterations of coronary ME include perifocal inflammatory edema and focal microinfarcts. Clinically, the detection of ME after successful coronary interventions identifies a population with a worse long-term prognosis. In 18 minipigs, ME was performed by intracoronary infusion of microspheres followed by repetitive in vivo imaging on a 1.5-T MR system from 30 min to 8 h after ME. Additionally, corresponding ex vivo CMR imaging and histomorphology were performed. Cine CMR imaging demonstrated a time-dependent increase of wall motion abnormalities from 9 of 18 animals after 30 min to all animals after 8 h (0.5 h, 50%; 2 h, 78%; 4 h, 75%; 8 h, 100%). Whereas T2 images were negative 30 min after ME, 4 of 18 animals showed myocardial edema at follow-up (0.5 h, 0%; 2 h, 6%; 4 h, 25%; 8 h, 17%). In vivo late gadolinium enhancement (LGE) was observed in none of the animals after 30 min, but in 33%, 50%, and 83% of animals at 2 h, 4 h, and 8 h, respectively, after ME. Ex vivo CMR imaging showed patchy areas of LGE in all but 1 animal (2 h, 83%; 4 h, 100%; 8 h, 100%). A significant correlation was seen between the maximum troponin I level and LGE in vivo (r = 0.63) and the spatial extent of ex vivo LGE (r = 0.76). Our results show that in vivo contrast-enhanced CMR imaging allows us to detect functional and structural myocardial changes after ME with a high sensitivity. Ex vivo, the pattern of LGE of high-resolution, contrast-enhanced CMR imaging is different from the well-known pattern of LGE in compact myocardial damage. Thus, improvements in spatial resolution are thought to be necessary to improve its ability to visualize ME-induced structural alterations even in vivo.

  4. Alignment of SWNTs by protein-ligand interaction of functionalized magnetic particles under low magnetic fields.

    PubMed

    Park, Tae Jung; Park, Jong Pil; Lee, Seok Jae; Jung, Dae-Hwan; Ko, Young Koan; Jung, Hee-Tae; Lee, Sang Yup

    2011-05-01

    Carbon nanotubes (CNTs) have attracted considerable attention for applications using their superior mechanical, thermal and electrical properties. A simple method to controllably align single-walled CNTs (SWNTs) by using magnetic particles embedded with superparamagnetic iron oxide as an accelerator under the magnetic field was developed. The functionalization of SWNTs using biotin, interacted with streptavidin-coupled magnetic particles (micro-to-nano in diameter), and layer-by-layer assembly were performed for the alignment of a particular direction onto the clean silicon and the gold substrate at very low magnetic forces (0.02-0.89 T) at room temperature. The successful alignment of the SWNTs with multi-layer film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By changing the orientation and location of the substrates, crossed-networks of SWNTs-magnetic particle complex could easily be fabricated. We suggest that this approach, which consists of a combination of biological interaction among streptavidin-biotin and magnetite particles, should be useful for lateral orientation of individual SWNTs with controllable direction.

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

    PubMed Central

    Chaudhary, Suman; Smith, Carol Anne; del Pino, Pablo; de la Fuente, Jesus M.; Mullin, Margaret; Hursthouse, Andrew; Stirling, David; Berry, Catherine C.

    2013-01-01

    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. PMID:24275948

  6. Functional magnetic resonance imaging of the brain: a quick review.

    PubMed

    Vaghela, Viratsinh; Kesavadas, Chandrasekharan; Thomas, Bejoy

    2010-01-01

    Ability to non-invasively map the hemodynamic changes occurring focally in areas of brain involved in various motor, sensory and cognitive functions by functional magnetic resonance imaging (fMRI) has revolutionized research in neuroscience in the last two decades. This technique has already gained clinical use especially in pre-surgical evaluation of epilepsy and neurosurgical planning of resection of mass lesions adjacent to eloquent cortex. In this review we attempt to illustrate basic principles and techniques of fMRI, its applications, practical points to consider while performing and evaluating clinical fMRI and its limitations.

  7. Fabrication and characterisation of 2NDPA-loaded poly(lactide-co-glycolide) (PLG) microspheres for explosive safety.

    PubMed

    Shorty, Marvin; Singh, Saurabh; Jebrail, Farzaneh F; Andrews, Malcolm J

    2012-01-01

    We demonstrate the microencapsulation of a double-base (DB) rocket propellant stabiliser, 2-nitrodiphenylamine (2-NDPA), that can potentially increase the shelf life of DB rocket propellants. Poly(lactide-co-glycolide) (PLG) microspheres loaded with 2-NDPA were prepared using the oil-in-water emulsion technique. The microsphere size was found to be inversely related to the mixing rate. It was also found that a higher theoretical loading of 2-NDPA resulted in larger microspheres. In addition, a Rosin Rammler distribution function gave an accurate representation of the microsphere size distribution, and the release rate 2-NDPA from PLG microspheres was found to be size dependent. We show that parameters such as the stirring speed and the percent loading of 2-NDPA can be varied to tailor the release of 2-NDPA from PLG microspheres. In addition, we have shown that temperature has a dramatic effect on the release of 2-NDPA from PLG microcapsules.

  8. Gold nanoparticles-coated magnetic microspheres as affinity matrix for detection of hemoglobin A1c in blood by microfluidic immunoassay.

    PubMed

    Chen, Shao-Peng; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2011-08-15

    A novel microfluidic immunoassay system for specific detection of hemoglobin A1c (HbA1c) was developed based on a three-component shell/shell/core structured magnetic nanocomposite Au/chitosan/Fe(3)O(4), which was synthesized with easy handling feature of Fe(3)O(4) by magnet, high affinity for gold nanoparticles of chitosan and good immobilization ability for anti-human hemoglobin-A1c antibody (HbA1c mAb) of assembled colloidal gold nanoparticles. The resulting HbA1c mAb/Au/chitosan/Fe(3)O(4) magnetic nanoparticles were then introduced into microfluidic devices coupled with a gold nanoband microelectrode as electrochemical detector. After that, three-step rapid immunoreactions were carried out in the sequence of HbA1c, anti-human hemoglobin antibodies (Hb mAb) and the secondary alkaline phosphatase (AP)-conjugated antibody within 20 min. The current response of 1-naphtol obtained from the reaction between the secondary AP-conjugated antibody and 1-naphthyl phosphate (1-NP) increased proportionally to the HbA1c concentration. Under optimized electrophoresis and detection conditions, HbA1c responded linearly in the concentration of 0.05-1.5 μg mL(-1), with the detection limit of 0.025 μg mL(-1). This system was successfully employed for detection of HbA1c in blood with good accuracy and renewable ability. The proposed method proved its potential use in clinical immunoassay of HbA1c.

  9. Magnetic Alignment and Charge Transport Improvement in Functional Soft Materials

    NASA Astrophysics Data System (ADS)

    Majewski, Pawel W.

    The realization of nanostructured functional materials by self-assembly in polymers and polymer nanocomposites is adversely affected by persisting structural defects which greatly diminish the performance of the material. The use of magnetic fields to impose long-range order is investigated in three distinct systems - ion-conducting block copolymers, semiconducting nanowire-polymer composites and lyotropic surfactant mesophases. The alignment process is quantitatively studied with X-ray scattering and microscopic methods. Time and temperature resolved data collected in situ during the magnetic experiments provide an insight into the thermodynamic and kinetic aspects of the process. These data together with simultaneous electrical conductivity measurements allow relating fundamental structural properties (e.g., morphology and long-range order) to transport properties (i.e., conductivity). In particular, it is demonstrated that magnetic fields offer a viable route for improvement of electric conductivity in these systems. More than an order of magnitude increase in conductivity is recorded in magnetically-annealed materials. The resulting aligned nanostructured systems are attractive for ordered solid polymer electrolyte membranes, heterojunction photovoltaic devices and generally help to understand charge transport mechanisms in anisotropic heterogeneous systems.

  10. Highly efficient and porous TiO2-coated Ag@Fe3O4@C-Au microspheres for degradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Shen, Mao; Chen, Suqing; Jia, Wenping; Fan, Guodong; Jin, Yanxian; Liang, Huading

    2016-12-01

    In this paper, we reported a novel hierarchical porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres with a highly photocatalytic activity and magnetically separable properties. The synthesis method is included of a Fe3O4 magnetic embedded Ag core (Ag@Fe3O4), an interlayer of carbon modified by PEI to form sufficient amounts of amine functional groups (Ag@Fe3O4@C-PEI), the grafting of Au nanoparticles on the surface of Ag@Fe3O4@C-PEI (Ag@Fe3O4@C-Au), and an ordered porous TiO2 structured shell. As an example of the applications, the photocatalytic activities of the samples were investigated by the reduction of Rhodamine B (RhB) under visible-light irradiation. The results show that the porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres display higher adsorption and photocatalytic activities compared to the pure porous TiO2 and Ag@Fe3O4@C@TiO2 microspheres, which are attributed to the local surface plasmon resonance (LSPR) by the Ag and Au nanoparticles and the high specific surface area.

  11. Magnetically separable Fe3O4@SiO2@TiO2-Ag microspheres with well-designed nanostructure and enhanced photocatalytic activity.

    PubMed

    Chi, Yue; Yuan, Qing; Li, Yanjuan; Zhao, Liang; Li, Nan; Li, Xiaotian; Yan, Wenfu

    2013-11-15

    Major efforts in modern material chemistry are devoted to the design and fabrication of nanostructured systems with tunable physical-chemical properties for advanced catalytic applications. Here, a novel Fe3O4@SiO2@TiO2-Ag nanocomposite has been synthesized and characterized by a series of techniques including SEM, TEM, XRD, XPS as well as magnetization measurement and subsequently tested for the photocatalytic activities. The well-designed nanocomposite exhibits significantly superior activity to that of the commercial Degussa P25 thanks to the suppression of electron-hole pairs from recombination by Ag nanoparticles, and can be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 10 times. The unique nanostructure makes Fe3O4@SiO2@TiO2-Ag a highly efficient, recoverable, stable, and cost-effective photocatalytic system offering broad opportunities in the field of catalyst synthesis and application.

  12. The physics of functional magnetic resonance imaging (fMRI)

    PubMed Central

    Buxton, Richard B

    2015-01-01

    Functional magnetic resonance imaging (fMRI) is a methodology for detecting dynamic patterns of activity in the working human brain. Although the initial discoveries that led to fMRI are only about 20 years old, this new field has revolutionized the study of brain function. The ability to detect changes in brain activity has a biophysical basis in the magnetic properties of deoxyhemoglobin, and a physiological basis in the way blood flow increases more than oxygen metabolism when local neural activity increases. These effects translate to a subtle increase in the local magnetic resonance signal, the blood oxygenation level dependent (BOLD) effect, when neural activity increases. With current techniques, this pattern of activation can be measured with resolution approaching 1 mm3 spatially and 1 s temporally. This review focuses on the physical basis of the BOLD effect, the imaging methods used to measure it, the possible origins of the physiological effects that produce a mismatch of blood flow and oxygen metabolism during neural activation, and the mathematical models that have been developed to understand the measured signals. An overarching theme is the growing field of quantitative fMRI, in which other MRI methods are combined with BOLD methods and analyzed within a theoretical modeling framework to derive quantitative estimates of oxygen metabolism and other physiological variables. That goal is the current challenge for fMRI: to move fMRI from a mapping tool to a quantitative probe of brain physiology. PMID:24006360

  13. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, W.E.

    1982-09-30

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  14. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, William E.

    1984-01-01

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  15. Brightness of Solar Magnetic Elements As a Function of Magnetic Flux at High Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Kahil, F.; Riethmüller, T. L.; Solanki, S. K.

    2017-03-01

    We investigate the relationship between the photospheric magnetic field of small-scale magnetic elements in the quiet-Sun (QS) at disk center and the brightness at 214, 300, 313, 388, 397, and 525.02 nm. To this end, we analyzed spectropolarimetric and imaging time series acquired simultaneously by the Imaging Magnetograph eXperiment magnetograph and the SuFI filter imager on board the balloon-borne observatory {{S}}{{UNRISE}} during its first science flight in 2009, with high spatial and temporal resolution. We find a clear dependence of the contrast in the near ultraviolet and the visible on the line-of-sight component of the magnetic field, B LOS, which is best described by a logarithmic model. This function effectively represents the relationship between the Ca ii H-line emission and B LOS and works better than the power-law fit adopted by previous studies. This, along with the high contrast reached at these wavelengths, will help with determining the contribution of small-scale elements in the QS to the irradiance changes for wavelengths below 388 nm. At all wavelengths, including the continuum at 525.40 nm, the intensity contrast does not decrease with increasing B LOS. This result also strongly supports the fact that {{S}}{{UNRISE}} has resolved small strong magnetic field elements in the internetwork, resulting in constant contrasts for large magnetic fields in our continuum contrast at 525.40 nm versus the B LOS scatterplot, unlike the turnover obtained in previous observational studies. This turnover is due to the intermixing of the bright magnetic features with the dark intergranular lanes surrounding them.

  16. Amine functionalized magnetic nanoparticles for removal of oil droplets from produced water and accelerated magnetic separation

    NASA Astrophysics Data System (ADS)

    Ko, Saebom; Kim, Eun Song; Park, Siman; Daigle, Hugh; Milner, Thomas E.; Huh, Chun; Bennetzen, Martin V.; Geremia, Giuliano A.

    2017-04-01

    Magnetic nanoparticles (MNPs) with surface coatings designed for water treatment, in particular for targeted removal of contaminants from produced water in oil fields, have drawn considerable attention due to their environmental merit. The goal of this study was to develop an efficient method of removing very stable, micron-scale oil droplets dispersed in oilfield produced water. We synthesized MNPs in the laboratory with a prescribed surface coating. The MNPs were superparamagnetic magnetite, and the hydrodynamic size of amine functionalized MNPs ranges from 21 to 255 nm with an average size of 66 nm. The initial oil content of 0.25 wt.% was reduced by as much as 99.9% in separated water. The electrostatic attraction between negatively charged oil-in-water emulsions and positively charged MNPs controls, the attachment of MNPs to the droplet surface, and the subsequent aggregation of the electrically neutral oil droplets with attached MNPs (MNPs-oils) play a critical role in accelerated and efficient magnetic separation. The total magnetic separation time was dramatically reduced to as short as 1 s after MNPs, and oil droplets were mixed, in contrast with the case of free, individual MNPs with which separation took about 36˜72 h, depending on the MNP concentrations. Model calculations of magnetic separation velocity, accounting for the MNP magnetization and viscous drag, show that the total magnetic separation time will be approximately 5 min or less, when the size of the MNPs-oils is greater than 360 nm, which can be used as an optimum operating condition.

  17. Nuclear chiral and magnetic rotation in covariant density functional theory

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Zhao, Pengwei

    2016-05-01

    Excitations of chiral rotation observed in triaxial nuclei and magnetic and/or antimagnetic rotations (AMR) seen in near-spherical nuclei have attracted a lot of attention. Unlike conventional rotation in well-deformed or superdeformed nuclei, here the rotational axis is not necessary coinciding with any principal axis of the nuclear density distribution. Thus, tilted axis cranking (TAC) is mandatory to describe these excitations self-consistently in the framework of covariant density functional theory (CDFT). We will briefly introduce the formalism of TAC-CDFT and its application for magnetic and AMR phenomena. Configuration-fixed CDFT and its predictions for nuclear chiral configurations and for favorable triaxial deformation parameters are also presented, and the discoveries of the multiple chiral doublets in 133Ce and 103Rh are discussed.

  18. Suspension Plasma Spray Fabrication of Nanocrystalline Titania Hollow Microspheres for Photocatalytic Applications

    NASA Astrophysics Data System (ADS)

    Ren, Kun; Liu, Yi; He, Xiaoyan; Li, Hua

    2015-10-01

    Hollow inorganic microspheres with controlled internal pores in close-cell configuration are usually constructed by submicron-sized particles. Fast and efficient large-scale production of the microspheres with tunable sizes yet remains challenging. Here, we report a suspension plasma spray route for making hollow microspheres from nano titania particles. The processing permits most nano particles to retain their physiochemical properties in the as-sprayed microspheres. The microspheres have controllable interior cavities and mesoporous shell of 1-3 μm in thickness. Spray parameters and organic content in the starting suspension play the key role in regulating the efficiency of accomplishing the hollow sphere structure. For the ease of collecting the spheres for recycling use, ferriferous oxide particles were used as additives to make Fe3O4-TiO2 hollow magnetic microspheres. The spheres can be easily recycled through external magnetic field collection after each time use. Photocatalytic anti-bacterial activities of the hollow spheres were assessed by examining their capability of degrading methylene blue and sterilizing Escherichia coli bacteria. Excellent photocatalytic performances were revealed for the hollow spheres, giving insight into their potential versatile applications.

  19. Fabrication of chitin microspheres and their multipurpose application as catalyst support and adsorbent.

    PubMed

    Wang, Yuntao; Li, Yan; Liu, Shilin; Li, Bin

    2015-04-20

    In this study, novel chitin microspheres (CM) with diameters of 1010 μm, 750 μm, 490 μm, 280 μm were fabricated by employing the sol-gel transition method. Then the chitin microspheres served as the enabling platform for a range of applications including recyclable catalyst support and adsorbent. First, the freeze dried porous chitin microspheres were coated with dopamine to enhance the loading efficiency of a model biomacromolecule, α-amylase. The immobilized enzyme (49.6 mg/g) retained more than 95% of relative activity after 10 repeated cycles and exhibited easy recovery ability. Then porous magnetic chitin microspheres could be prepared, and the swollen porous polymer successfully controlled the growth of gold nanoparticles. The chitin/Au nanocomposite microspheres were a good recyclable catalyst due to the porous structure and a reduced dimension of the metal particles (r ≤ 5 nm). Finally, the magnetic chitin microspheres were modified into an adsorbent for enhanced removal of a typical cationic compound, methylene blue from aqueous solution. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Microspheres and their methods of preparation

    DOEpatents

    Bose, Anima B; Yang, Junbing

    2015-03-24

    Carbon microspheres are doped with boron to enhance the electrical and physical properties of the microspheres. The boron-doped carbon microspheres are formed by a CVD process in which a catalyst, carbon source and boron source are evaporated, heated and deposited onto an inert substrate.

  1. Fabrication of core-shell Fe3O4@MIL-100(Fe) magnetic microspheres for the removal of Cr(VI) in aqueous solution

    NASA Astrophysics Data System (ADS)

    Yang, Qingxiang; Zhao, Qianqian; Ren, ShuangShuang; Lu, Qiongqiong; Guo, Xinmeng; Chen, Zhijun

    2016-12-01

    Facile regeneration of an adsorbent is very important for commercial feasibility. One typical highly porous metal-organic framework (MOF) materials based on MIL-100(Fe) and magnetic iron oxide particles (denoted as MMCs) with diameter about of 350 nm were successfully synthesized. The growth of MIL-100(Fe) shell on the surface of Fe3O4 was utilized precursor as crystal seed via in-situ step hydrothermal reaction. It is a simple way to obtain well organized core-shell MOF composites, compared to the step-by-step method. MMCs were firstly used to uptake of Cr(VI) anions in aqueous solution. Adsorption experiments were carried out in batch sorption mode investigating with the factors of contact time (0-1000 min), pH (from 2 to 12), dose of adsorbent (4-25 mg), and initial Cr(VI) concentration (range from 10 to 100 ppm).

  2. How to Perform and Interpret Functional Magnetic Resonance Imaging Studies in Functional Gastrointestinal Disorders

    PubMed Central

    Lee, In-Seon; Preissl, Hubert; Enck, Paul

    2017-01-01

    Functional neuroimaging studies have revealed the importance of the role of cognitive and psychological factors and the dysregulation of the brain-gut axis in functional gastrointestinal disorder patients. Although only a small number of neuroimaging studies have been conducted in functional gastrointestinal disorder patients, and despite the fact that the neuroimaging technique requires a high level of knowledge, the technique still has a great deal of potential. The application of functional magnetic resonance imaging (fMRI) technique in functional gastrointestinal disorders should provide novel methods of diagnosing and treating patients. In this review, basic knowledge and technical/practical issues of fMRI will be introduced to clinicians. PMID:28256119

  3. How to Perform and Interpret Functional Magnetic Resonance Imaging Studies in Functional Gastrointestinal Disorders.

    PubMed

    Lee, In-Seon; Preissl, Hubert; Enck, Paul

    2017-04-30

    Functional neuroimaging studies have revealed the importance of the role of cognitive and psychological factors and the dysregulation of the brain-gut axis in functional gastrointestinal disorder patients. Although only a small number of neuroimaging studies have been conducted in functional gastrointestinal disorder patients, and despite the fact that the neuroimaging technique requires a high level of knowledge, the technique still has a great deal of potential. The application of functional magnetic resonance imaging (fMRI) technique in functional gastrointestinal disorders should provide novel methods of diagnosing and treating patients. In this review, basic knowledge and technical/practical issues of fMRI will be introduced to clinicians.

  4. Parameter optimization for photonic nanojet of dielectric microsphere

    NASA Astrophysics Data System (ADS)

    Ku, Yu-long; Kuang, Cui-fang; Hao, Xiang; Li, Hai-feng; Liu, Xu

    2013-03-01

    The characteristics of photonic nanojets are analyzed by changing the parameters, such as the wavelength, refractive index of the surroundings, diameter and refractive index of the microsphere, in this paper. Quadratic functions are used to describe the relation between the above parameters and photonic nanojets' characteristics. Several techniques are proposed to control the photonic nanojets.

  5. Multilayered polymer microspheres by thermal imprinting during microsphere growth.

    PubMed

    Takekoh, Ryu; Li, Wen-Hui; Burke, Nicholas A D; Stöver, Harald D H

    2006-01-11

    Modulation of the polymerization temperature in precipitation polymerizations was used to form onion-type polymer microspheres consisting of multiple nested layers. Specifically, the copolymerization of chloromethylstyrene and divinylbenzene-55 in acetonitrile, at temperatures ramping between 65 and 75 degrees C, led to monodisperse, cross-linked microspheres of about 10 mum diameter that have radial density profiles closely reflecting the thermal profiles used. This thermal imprinting is attributed to the copolymer formed being close to its theta point during the polymerization. As the microspheres grow by continuously capturing oligomers from solution, the resulting transient surface gel layer expands and contracts with temperature, and thus records the reaction temperature profile in the form of a corresponding density profile, even as it cross-links.

  6. Magnetic field shift due to mechanical vibration in functional magnetic resonance imaging.

    PubMed

    Foerster, Bernd U; Tomasi, Dardo; Caparelli, Elisabeth C

    2005-11-01

    Mechanical vibrations of the gradient coil system during readout in echo-planar imaging (EPI) can increase the temperature of the gradient system and alter the magnetic field distribution during functional magnetic resonance imaging (fMRI). This effect is enhanced by resonant modes of vibrations and results in apparent motion along the phase encoding direction in fMRI studies. The magnetic field drift was quantified during EPI by monitoring the resonance frequency interleaved with the EPI acquisition, and a novel method is proposed to correct the apparent motion. The knowledge on the frequency drift over time was used to correct the phase of the k-space EPI dataset. Since the resonance frequency changes very slowly over time, two measurements of the resonance frequency, immediately before and after the EPI acquisition, are sufficient to remove the field drift effects from fMRI time series. The frequency drift correction method was tested "in vivo" and compared to the standard image realignment method. The proposed method efficiently corrects spurious motion due to magnetic field drifts during fMRI. (c) 2005 Wiley-Liss, Inc.

  7. Advances in Microsphere Insulation Systems

    NASA Astrophysics Data System (ADS)

    Allen, M. S.; Baumgartner, R. G.; Fesmire, J. E.; Augustynowicz, S. D.

    2004-06-01

    Microsphere insulation, typically consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. Microspheres provide robust, low-maintenance insulation systems for cryogenic transfer lines and dewars. They also do not suffer from compaction problems typical of perlite that result in the necessity to reinsulate dewars because of degraded thermal performance and potential damage to its support system. Since microspheres are load bearing, autonomous insulation panels enveloped with lightweight vacuum-barrier materials can be created. Comprehensive testing performed at the Cryogenics Test Laboratory located at the NASA Kennedy Space Center demonstrated competitive thermal performance with other bulk materials. Test conditions were representative of actual-use conditions and included cold vacuum pressure ranging from high vacuum to no vacuum and compression loads from 0 to 20 psi. While microspheres have been recognized as a legitimate insulation material for decades, actual implementation has not been pursued. Innovative microsphere insulation system configurations and applications are evaluated.

  8. Fast instability caused by electron cloud in combined function magnets

    DOE PAGES

    Antipov, S. A.; Adamson, P.; Burov, A.; ...

    2017-04-10

    One of the factors which may limit the intensity in the Fermilab Recycler is a fast transverse instability. It develops within a hundred turns and, in certain conditions, may lead to a beam loss. The high rate of the instability suggest that its cause is electron cloud. Here, we studied the phenomena by observing the dynamics of stable and unstable beam, simulating numerically the build-up of the electron cloud, and developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function di-poles. We also found that beam motion can be stabilized by a clearingmore » bunch, which confirms the electron cloud nature of the instability. The clearing suggest electron cloud trapping in Recycler combined function mag-nets. Numerical simulations show that up to 1% of the particles can be trapped by the magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. Furthermore, in a Recycler combined function dipole this multi-turn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The estimated resulting instability growth rate of about 30 revolutions and the mode fre-quency of 0.4 MHz are consistent with experimental observations and agree with the simulation in the PEI code. The created instability model allows investigating the beam stability for the future intensity upgrades.« less

  9. Fast Instability Caused by Electron Cloud in Combined Function Magnets

    SciTech Connect

    Antipov, S. A.; Adamson, P.; Burov, A.; Nagaitsev, S.; Yang, M. J.

    2016-12-12

    One of the factors which may limit the intensity in the Fermilab Recycler is a fast transverse instability. It develops within a hundred turns and, in certain conditions, may lead to a beam loss. The high rate of the instability suggest that its cause is electron cloud. We studied the phenomena by observing the dynamics of stable and unstable beam, simulating numerically the build-up of the electron cloud, and developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function di-poles. We found that beam motion can be stabilized by a clearing bunch, which confirms the electron cloud nature of the instability. The clearing suggest electron cloud trapping in Recycler combined function mag-nets. Numerical simulations show that up to 1% of the particles can be trapped by the magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multi-turn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The estimated resulting instability growth rate of about 30 revolutions and the mode fre-quency of 0.4 MHz are consistent with experimental observations and agree with the simulation in the PEI code. The created instability model allows investigating the beam stability for the future intensity upgrades.

  10. Linear constraint minimum variance beamformer functional magnetic resonance inverse imaging.

    PubMed

    Lin, Fa-Hsuan; Witzel, Thomas; Zeffiro, Thomas A; Belliveau, John W

    2008-11-01

    Accurate estimation of the timing of neural activity is required to fully model the information flow among functionally specialized regions whose joint activity underlies perception, cognition and action. Attempts to detect the fine temporal structure of task-related activity would benefit from functional imaging methods allowing higher sampling rates. Spatial filtering techniques have been used in magnetoencephalography source imaging applications. In this work, we use the linear constraint minimal variance (LCMV) beamformer localization method to reconstruct single-shot volumetric functional magnetic resonance imaging (fMRI) data using signals acquired simultaneously from all channels of a high density radio-frequency (RF) coil array. The LCMV beamformer method generalizes the existing volumetric magnetic resonance inverse imaging (InI) technique, achieving higher detection sensitivity while maintaining whole-brain spatial coverage and 100 ms temporal resolution. In this paper, we begin by introducing the LCMV reconstruction formulation and then quantitatively assess its performance using both simulated and empirical data. To demonstrate the sensitivity and inter-subject reliability of volumetric LCMV InI, we employ an event-related design to probe the spatial and temporal properties of task-related hemodynamic signal modulations in primary visual cortex. Compared to minimum-norm estimate (MNE) reconstructions, LCMV offers better localization accuracy and superior detection sensitivity. Robust results from both single subject and group analyses demonstrate the excellent sensitivity and specificity of volumetric InI in detecting the spatial and temporal structure of task-related brain activity.

  11. Functional magnetic resonance: biomarkers of response in breast cancer

    PubMed Central

    2011-01-01

    Functional magnetic resonance (MR) encompasses a spectrum of techniques that depict physiological and molecular processes before morphological changes are visible on conventional imaging. As understanding of the pathophysiological and biomolecular processes involved in breast malignancies evolves, newer functional MR techniques can be employed that define early predictive and surrogate biomarkers for monitoring response to chemotherapy. Neoadjuvant chemotherapy is increasingly used in women with primary breast malignancies to down-stage the tumour and enable successful breast conservation surgery. It also plays a role in the treatment of undetected micrometastases. Cardinal physiological features of tumours that occur as a result of interactions between cancer cells, stromal cells and secreted factors and cytokines and how they change with treatment provide the opportunity to detect changes in the tumour microenvironment prior to any morphological change. Through sequential imaging, tumour response can be assessed and non-responders can be identified early to enable alternative therapies to be considered. This review summarises the functional magnetic resonance biomarkers of response in patients with breast cancer that are currently available and under development. We describe the current state of each biomarker and explore their potential clinical uses and limitations in assessing treatment response. With the aid of selected interesting cases, biomarkers related to dynamic contrast-enhanced MRI, diffusion-weighted MRI, T2*/BOLD and MR spectroscopy are described and illustrated. The potential of newer approaches, such as MR elastography, are also reviewed. PMID:21392409

  12. Fast instability caused by electron cloud in combined function magnets

    NASA Astrophysics Data System (ADS)

    Antipov, S. A.; Adamson, P.; Burov, A.; Nagaitsev, S.; Yang, M.-J.

    2017-04-01

    One of the factors which may limit the intensity in the Fermilab Recycler is a fast transverse instability. It develops within a hundred turns and, in certain conditions, may lead to a beam loss. The high rate of the instability suggests that its cause is electron cloud. We studied the phenomena by observing the dynamics of stable and unstable beams, simulating numerically the buildup of the electron cloud, and developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function dipoles. We found that beam motion can be stabilized by a clearing bunch, which confirms the electron cloud nature of the instability. The clearing suggest electron cloud trapping in Recycler combined function magnets. Numerical simulations show that up to 1% of the particles can be trapped by the magnetic field. Since the process of electron cloud buildup is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multiturn accumulation allows the electron cloud to reach final intensities orders of magnitude greater than in a pure dipole. The estimated resulting instability growth time of about 30 revolutions and the mode frequency of 0.4 MHz are consistent with experimental observations and agree with the simulation in the pei code. The created instability model allows investigating the beam stability for the future intensity upgrades.

  13. The use of magnetite-doped polymeric microspheres in calibrating cell tracking velocimetry.

    PubMed

    Moore, L R; Zborowski, M; Nakamura, M; McCloskey, K; Gura, S; Zuberi, M; Margel, S; Chalmers, J J

    2000-07-10

    Continuous magnetic separation, in which there is no accumulation of mass in the system, is an inherently dynamic process, requiring advanced knowledge of the separable species for optimal instrument operation. By determining cell magnetization in a well-defined field, we may predict the cell trajectory behavior in the well-characterized field environments of our continuous separators. Magnetization is determined by tracking the migration of particles with a technique known as cell tracking velocimetry (CTV). The validation of CTV requires calibration against an external standard. Furthermore, such a standard, devoid of the variations and instabilities of biological systems, is needed to reference the method against day-to-day shifts or trends. To this end, a method of synthesizing monodisperse, magnetite-doped polymeric microspheres has been developed. Five sets of microspheres differing in their content of magnetite, and each of approximately 2.7 microm diameter, are investigated. An average gradient of 0.18 T/mm induces magnetic microsphere velocities ranging from 0.45 to 420 microns/s in the CTV device. The velocities enable calculation of the microsphere magnetization. Magnetometer measurements permit the determination of magnetization at a flux density comparable to that of the CTV magnet's analysis region, 1.57 T. A comparison of the results of the CTV and magnetometer measurements shows good agreement.

  14. Measurement of Scattering and Absorption Cross Sections of Dyed Microspheres

    PubMed Central

    Gaigalas, Adolfas K; Choquette, Steven; Zhang, Yu-Zhong

    2013-01-01

    Measurements of absorbance and fluorescence emission were carried out on aqueous suspensions of polystyrene (PS) microspheres with a diameter of 2.5 µm using a spectrophotometer with an integrating sphere detector. The apparatus and the principles of measurements were described in our earlier publications. Microspheres with and without green BODIPY@ dye were measured. Placing the suspension inside an integrating sphere (IS) detector of the spectrophotometer yielded (after a correction for fluorescence emission) the absorbance (called A in the text) due to absorption by BODIPY@ dye inside the microsphere. An estimate of the absorbance due to scattering alone was obtained by subtracting the corrected BODIPY@ dye absorbance (A) from the measured absorbance of a suspension placed outside the IS detector (called A1 in the text). The absorption of the BODIPY@ dye inside the microsphere was analyzed using an imaginary index of refraction parameterized with three Gaussian-Lorentz functions. The Kramer-Kronig relation was used to estimate the contribution of the BODIPY@ dye to the real part of the microsphere index of refraction. The complex index of refraction, obtained from the analysis of A, was used to analyze the absorbance due to scattering ((A1- A) in the text). In practice, the analysis of the scattering absorbance, A1-A, and the absorbance, A, was carried out in an iterative manner. It was assumed that A depended primarily on the imaginary part of the microsphere index of refraction with the other parameters playing a secondary role. Therefore A was first analyzed using values of the other parameters obtained from a fit to the absorbance due to scattering, A1-A, with the imaginary part neglected. The imaginary part obtained from the analysis of A was then used to reanalyze A1-A, and obtain better estimates of the other parameters. After a few iterations, consistent estimates were obtained of the scattering and absorption cross sections in the wavelength region 300

  15. The economics of functional magnetic resonance imaging: clinical and research.

    PubMed

    Yousem, David M

    2014-11-01

    It is difficult to justify maintaining a clinical functional magnetic resonance imaging (fMRI) program based solely on revenue generation. The use of fMRI is, therefore, based mostly in patient care considerations, leading to better outcomes. The high costs of the top-of-the-line equipment, hardware, and software needed for state-of-the-art fMRI and the time commitment by multiple professionals are not adequately reimbursed at a representative rate by current payor schemes for the Current Procedure Terminology codes assigned. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Peptide-functionalized iron oxide magnetic nanoparticle for gold mining

    NASA Astrophysics Data System (ADS)

    Shen, Wei-Zheng; Cetinel, Sibel; Sharma, Kumakshi; Borujeny, Elham Rafie; Montemagno, Carlo

    2017-02-01

    Here, we present our work on preparing a novel nanomaterial composed of inorganic binding peptides and magnetic nanoparticles for inorganic mining. Two previously selected and well-characterized gold-binding peptides from cell surface display, AuBP1 and AuBP2, were exploited. This nanomaterial (AuBP-MNP) was designed to fulfill the following two significant functions: the surface conjugated gold-binding peptide will recognize and selectively bind to gold, while the magnetic nano-sized core will respond and migrate according to the applied external magnetic field. This will allow the smart nanomaterial to mine an individual material (gold) from a pool of mixture, without excessive solvent extraction, filtration, and concentration steps. The working efficiency of AuBP-MNP was determined by showing a dramatic reduction of gold nanoparticle colloid concentration, monitored by spectroscopy. The binding kinetics of AuBP-MNP onto the gold surface was determined using surface plasmon resonance (SPR) spectroscopy, which exhibits around 100 times higher binding kinetics than peptides alone. The binding capacity of AuBP-MNP was demonstrated by a bench-top mining test with gold microparticles.

  17. Poly(lactide-co-glycolide) Microspheres for MRI-Monitored Delivery of Sorafenib in a Rabbit VX2 model

    PubMed Central

    Chen, Jeane; White, Sarah B.; Harris, Kathleen R.; Li, Weiguo; Yap, Jonathan WT; Kim, Dong-Hyun; Lewandowski, Robert J.; Shea, Lonnie D.; Larson, Andrew C.

    2015-01-01

    Transcatheter arterial embolization and chemoembolization are standard locoregional therapies for hepatocellular carcinoma (HCC). However, these can result in tumor hypoxia, thus promoting tumor angiogenesis. The anti-angiogenic agent sorafenib is hypothesized to improve outcomes; however, oral administration limits patient tolerance. Therefore, the purpose of this study was to fabricate poly(lactide-co-glycolide) microspheres for local sorafenib delivery to tumors during liver-directed embolotherapies. Iron oxide nanoparticles (IONP) were co-encapsulated for magnetic resonance imaging (MRI) of microsphere delivery. Microspheres were fabricated using a double emulsion/solvent evaporation method and characterized for size, sorafenib and IONP content, and MRI properties. MRI was performed before and after intra-arterial microsphere infusions in a rabbit VX2 liver tumor model. The microspheres were 13 microns in diameter with 8.8% and 0.89% (w/w) sorafenib and IONP, respectively. 21% and 28% of the loaded sorafenib and IONP, respectively, released within 72 hours. Rabbit VX2 studies demonstrated that sorafenib microspheres normalized VEGFR 2 activity and decreased microvessel density. Quantitative MRI enabled in vivo visualization of intra-hepatic microsphere distributions. These methods should avoid systemic toxicities, with MRI permitting follow-up confirmation of microsphere delivery to the targeted liver tumors. PMID:26022791

  18. Poly(lactide-co-glycolide) Microspheres for MRI-Monitored Transcatheter Delivery of Sorafenib to Liver Tumors

    PubMed Central

    Chen, Jeane; Sheu, Alexander Y.; Li, Weiguo; Zhang, Zhuoli; Kim, Dong-Hyun; Lewandowski, Robert J.; Omary, Reed A.; Shea, Lonnie D.; Larson, Andrew C.

    2014-01-01

    The multi-kinase inhibitor (MKI) sorafenib can be an effective palliative therapy for patients with hepatocellular carcinoma (HCC). However, patient tolerance is often poor due to common systemic side effects following oral administration. Local transcatheter delivery of sorafenib to liver tumors has the potential to reduce systemic toxicities while increasing the dose delivered to targeted tumors. We developed sorafenib-eluting PLG microspheres for delivery by intra-hepatic transcatheter infusion in an orthotropic rodent HCC model. The particles also encapsulated iron-oxide nanoparticles permitting magnetic resonance imaging (MRI) of intra-hepatic biodistributions. The PLG microspheres (diameter ≈1 μm) were loaded with 18.6% (w/w) sorafenib and 0.54% (w/w) ferrofluid and 65.2% of the sorafenib was released within 72 hours of media exposure. In vitro studies demonstrated significant reductions in HCC cell proliferation with increasing doses of the sorafenib-eluting microspheres, where the estimated IC50 was a 29 ug/mL dose of microspheres. During in vivo studies, MRI permitted intra-procedural visualization of intra-hepatic microsphere delivery. At 72 hours after microsphere infusion, microvessel density was significantly reduced in tumors treated with the sorafenib-eluting microspheres compared to both sham control tumors (by 35%) and controls (by 30%). These PLG microspheres offer the potential to increase the efficacy of molecularly targeted MKI therapies while reducing systemic exposures via selective catheter-directed delivery to HCC. PMID:24727059

  19. Polarization Dependent Whispering Gallery Modes in Microspheres

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory (Inventor); Wrbanek, Susan Y. (Inventor)

    2016-01-01

    A tunable resonant system is provided and includes a microsphere that receives an incident portion of a light beam generated via a light source, the light beam having a fundamental mode, a waveguide medium that transmits the light beam from the light source to the microsphere, and a polarizer disposed in a path of the waveguide between the light source and the microsphere. The incident portion of the light beam creates a fundamental resonance inside the microsphere. A change in a normalized frequency of the wavelength creates a secondary mode in the waveguide and the secondary mode creates a secondary resonance inside the microsphere.

  20. Localizing the site of magnetic brain stimulation by functional MRI.

    PubMed

    Terao, Y; Ugawa, Y; Sakai, K; Miyauchi, S; Fukuda, H; Sasaki, Y; Takino, R; Hanajima, R; Furubayashi, T; Pütz, B; Kanazawa, I

    1998-07-01

    In order to locate the site of action of transcranial magnetic stimulation (TMS) within the human motor cortices, we investigated how the optimal positions for evoking motor responses over the scalp corresponded to the hand and leg primary-motor areas. TMS was delivered with a figure-8 shaped coil over each point of a grid system constructed on the skull surface, each separated by 1 cm, to find the optimal site for obtaining motor-evoked potentials (MEPs) in the contralateral first dorsal interosseous (FDI) and tibialis anterior (TA) muscles. Magnetic resonance imaging scans of the brain were taken for each subject with markers placed over these sites, the positions of which were projected onto the cortical region just beneath. On the other hand, cortical areas where blood flow increased during finger tapping or leg movements were identified on functional magnetic resonance images (fMRI), which should include the hand and leg primary-motor areas. The optimal location for eliciting MEPs in FDI, regardless of their latency, lay just above the bank of the precentral gyrus, which coincided with the activated region during finger tapping in fMRI studies. The direction of induced current preferentially eliciting MEPs with the shortest latency in each subject was nearly perpendicular to the course of the precentral gyrus at this position. The optimal site for evoking motor responses in TA was also located just above the activated area during leg movements identified within the anterior portion of the paracentral lobule. The results suggest that, for magnetic stimulation, activation occurs in the primary hand and leg motor area (Brodmann area 4), which is closest in distance to the optimal scalp position for evoking motor responses.

  1. Absolute brightness of fluorescent microspheres.

    PubMed

    Finger, Isaac; Phillips, Scott; Mobley, Elizabeth; Tucker, Robert; Hess, Henry

    2009-02-07

    The absolute brightness of fluorescent particles, such as dye-containing nano- and microspheres or quantum dots, is a critical design parameter for many applications relying on fluorescence detection. The absolute brightness, defined as the ratio of radiant intensity of emission to illumination intensity of excitation, of nile-red fluorescent microspheres with a 1 micrometre diameter is measured to be 4.2 +/- 1 x 10(-16) m(2)/sr, and the implications for the design of kinesin motor protein-powered "smart dust" devices and the remote detection of fluorescence are discussed.

  2. Approach to combined-function magnets via symplectic slicing

    NASA Astrophysics Data System (ADS)

    Titze, M.

    2016-05-01

    In this article we describe how to obtain symplectic "slice" maps for combined-function magnets, by using a method of generating functions. A feature of this method is that one can use an unexpanded and unsplit Hamiltonian. From such a slice map we obtain a first-order map which is symplectic at the closed orbit. We also obtain a symplectic kick map. Both results were implemented into the widely used program MAD-X to regain, in particular, the twiss parameters for the sliced model of the Proton Synchrotron at CERN. In addition, we obtain recursion equations for symplectic maps of general time-dependent Hamiltonians, which might be useful even beyond the scope of accelerator physics.

  3. Synthesis of surface functionalized magnetic nanoparticles and their polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Miner, M. J.; Morales, M. B.; Poddar, P.; Srikanth, H.; Skidmore, S. M.; Weller, T. M.

    2008-03-01

    Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential in applications such as tunable microwave devices, EMI shielding, flexible electronics etc. Control over the dispersion of the nanoparticle phase embedded in a polymer matrix is critical and often challenging. To achieve excellent dispersion, competition between polymer-polymer and polymer-particle interactions must be balanced to avoid clustering of particles in polymer nanocomposites. In earlier work, we had demonstrated the successful synthesis of 2μm thick spin coated nanocomposite PMMA films with Fe3O4 (mean size 15nm) nanoparticle inclusions exhibiting superparamagnetic behavior. In this work, we will present our attempts to achieve thicker films more suitable for microwave applications and a study of the role of surface functionalization of ferrite nanoparticles synthesized using co-precipitation and hydrothermal routes. Cross-sectional SEM and TEM studies as well as magnetic characterization using a Physical Property Measurement System will be presented and discussed. We will also report on the microwave response of these films using a coplanar waveguide fixture. Work at USF supported by NSF through a GOALI grant from NSF-DMII.

  4. Functional nanocomposite polymer films with uniform magnetic nanoparticle dispersions

    NASA Astrophysics Data System (ADS)

    Stojak, K.; Pal, S.; Miner, M. J.; Srikanth, H.; Skidmore, S.; Wang, J.; Weller, T.

    2009-03-01

    Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential in applications such as tunable microwave devices, EMI shielding, and flexible electronics. The challenge comes with evenly dispersing the nanoparticles once they are embedded in the polymer matrix. To avoid clustering of particles in the polymer nanocomposites and achieve excellent dispersion, competition between polymer-polymer and polymer-particle interactions must be balanced. In earlier work, we demonstrated the synthesis of 2μm thick, spin-coated nanocomposite PMMA films with Fe3O4 (mean size 15nm) nanoparticles embedded that displayed superparamagnetic behavior. In this work we will report on the successful extension of this strategy to 20 μm thick films that are needed for microwave applications. In addition to Fe3O4, we have also functionalized the films with other ferrite nanoparticles. Magnetic characterization and microstructural studies of the polymer nanocomposites will be presented and discussed. Microwave response of these films using a coplanar waveguide fixture will also be reported.

  5. Functional magnetic resonance imaging at 0.2 Tesla.

    PubMed

    Stroman, P W; Malisza, K L; Onu, M

    2003-10-01

    Functional magnetic resonance imaging of healthy human volunteers was carried out at 0.2 T, using proton-density weighted (TE = 24 ms) spin-echo imaging, in order to eliminate any contribution from the blood oxygenation-level dependent (BOLD) effect. The purpose of the study was to verify the existence of a proton-density change contribution to spin-echo functional magnetic resonance imaging (fMRI) data. Results demonstrated signal intensity changes in motor and sensory areas of the brain during performance of a motor task and cold sensory stimulation of the hand, with signal changes ranging from 1.7 to 2.3%. These values are consistent with 1.9% signal changes observed previously under similar conditions at 3 T. These findings confirm the proton-density change contribution to spin-echo fMRI data and support the theory of signal enhancement by extravascular water protons (SEEP) as a non-BOLD fMRI contrast mechanism. This study also demonstrates that fMRI based on the SEEP contrast mechanism can be carried out at low fields where the BOLD effect is expected to be negligible.

  6. Room-temperature Magnetic Ordering in Functionalized Graphene

    PubMed Central

    Hong, Jeongmin; Bekyarova, Elena; Liang, Ping; de Heer, Walt A.; Haddon, Robert C.; Khizroev, Sakhrat

    2012-01-01

    Despite theoretical predictions, the question of room-temperature magnetic order in graphene must be conclusively resolved before graphene can fully achieve its potential as a spintronic medium. Through scanning tunneling microscopy (STM) and point I-V measurements, the current study reveals that unlike pristine samples, graphene nanostructures, when functionalized with aryl radicals, can sustain magnetic order. STM images show 1-D and 2-D periodic super-lattices originating from the functionalization of a single sub-lattice of the bipartite graphene structure. Field-dependent super-lattices in 3-nm wide “zigzag” nanoribbons indicate local moments with parallel and anti-parallel ordering along and across the edges, respectively. Anti-parallel ordering is observed in 2-D segments with sizes of over 20 nm. The field dependence of STM images and point I-V curves indicates a spin polarized local density of states (LDOS), an out-of-plane anisotropy field of less than 10 Oe, and an exchange coupling field of 100 Oe at room temperature. PMID:22953045

  7. Magnetic anisotropy of metal functionalized phthalocyanine 2D networks

    SciTech Connect

    Zhu, Guojun; Zhang, Yun; Xiao, Huaping; Cao, Juexian

    2016-06-15

    The magnetic anisotropy of metal including Cr, Mn, Fe, Co, Mo, Tc, Ru, Rh, W, Re, Os, Ir atoms functionalized phthalocyanine networks have been investigated with first-principles calculations. The magnetic moments can be expressed as 8-n μ{sub B} with n the electronic number of outmost d shell in the transition metals. The huge magnetocrystalline anisotropy energy (MAE) is obtained by torque method. Especially, the MAE of Re functionalized phthalocyanine network is about 20 meV with an easy axis perpendicular to the plane of phthalocyanine network. The MAE is further manipulated by applying the external biaxial strain. It is found that the MAE is linear increasing with the external strain in the range of −2% to 2%. Our results indicate an effective approach to modulate the MAE for practical application. - Graphical abstract: The charge density redistribution (ρ{sub MPc}-ρ{sub M}-ρ{sub Pc}) and spin density of the CoPc molecule, from top- and side-views. Purple and green isosurfaces indicate charge depletion and accumulation, respectively. Display Omitted.

  8. PEG-Functionalized Magnetic Nanoparticles for Drug Delivery and Magnetic Resonance Imaging Applications

    PubMed Central

    Yallapu, Murali Mohan; Foy, Susan P; Jain, Tapan K; Labhasetwar, Vinod

    2010-01-01

    Purpose Polyethylene glycol (PEG) functionalized magnetic nanoparticles (MNPs) were tested as a drug carrier system, magnetic resonance imaging (MRI) agent, and ability to conjugate to an antibody. Methods An iron oxide core coated with oleic acid (OA) and then with OA-PEG forms a water dispersible MNP formulation. Hydrophobic doxorubicin partitions into the OA layer for sustained drug delivery. The T1 and T2 MRI contrast properties were determined in vitro and the circulation of the MNPs measured in mouse carotid arteries. An N-hydroxysuccinimide group (NHS) on the OA-PEG-80 was used to conjugate the amine functional group on antibodies for active targeting in the human MCF-7 breast cancer cell line. Results The optimized formulation had a mean hydrodynamic diameter of 184 nm with an 8 nm iron-oxide core. The MNPs enhance the T2 MRI contrast, and have a long circulation time in vivo with 30% relative concentration 50 min post-injection. Doxorubicin-loaded MNPs showed sustained drug release and dose-dependent antiproliferative effects in vitro; the drug effect was enhanced with transferrin antibody conjugated MNPs. Conclusion PEG functionalized MNPs could be developed as a targeted drug delivery system and MRI contrast agent. PMID:20845067

  9. A General Method for Calculating the External Magnetic Field from a Cylindrical Magnetic Source using Toroidal Functions

    SciTech Connect

    J Selvaggi; S Salon; O Kwon CVK Chari

    2006-02-14

    An alternative method is developed to compute the magnetic field from a circular cylindrical magnetic source. Specifically, a Fourier series expansion whose coefficients are toroidal functions is introduced which yields an alternative to the more familiar spherical harmonic solution or the Elliptic integral solution. This alternate formulation coupled with a method called charge simulation allows one to compute the external magnetic field from an arbitrary magnetic source in terms of a toroidal expansion. This expansion is valid on any finite hypothetical external observation cylinder. In other words, the magnetic scalar potential or the magnetic field intensity is computed on a exterior cylinder which encloses the magnetic source. This method can be used to accurately compute the far field where a finite element formulation is known to be inaccurate.

  10. Improved antireflection coated microspheres for biological applications of optical tweezers

    NASA Astrophysics Data System (ADS)

    Ferro, Valentina; Sonnberger, Aaron; Abdosamadi, Mohammad K.; McDonald, Craig; Schäffer, Erik; McGloin, David

    2016-09-01

    The success of optical tweezers in cellular biology1 is in part due to the wide range of forces that can be applied, from femto- to hundreds of pico-Newtons; nevertheless extending the range of applicable forces to the nanoNewton regime opens access to a new set of phenomena that currently lie beyond optical manipulation. A successful approach to overcome the conventional limits on trapping forces involves the optimization of the trapped probes. Jannasch et al.2 demonstrated that an anti-reflective shell of nanoporous titanium dioxide (aTiO2, nshell = 1.75) on a core particle made out of titanium dioxide in the anatase phase (cTiO2, ncore = 2.3) results in trappable microspheres capable to reach forces above 1 nN. Here we present how the technique can be further improved by coating the high refractive index microspheres with an additional anti-reflective shell made out of silica (SiO2). This external shell not only improves the trap stability for microspheres of different sizes, but also enables the use of functionalization techniques already established for commercial silica beads in biological experiments. We are also investigating the use of these new microspheres as probes to measure adhesion forces between intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 1 (LFA-1) in effector T-Cells and will present preliminary results comparing standard and high-index beads.

  11. Development of biodegradable radiopaque microsphere for arterial embolization-a pig study

    PubMed Central

    Liu, Yi-Sheng; Lin, Xi-Zhang; Tsai, Hong-Ming; Tsai, Hung-Wen; Chen, Guan-Cheng; Chen, Syuan-Fong; Kang, Jui-Wen; Chou, Chen-Miao; Chen, Chiung-Yu

    2015-01-01

    AIM: To develop a new type of calibrated, biodegradable, and imaging detectable microsphere and evaluated its embolization safety and efficacy on pig’s liver and spleen. METHODS: Six kinds of pharmaceutical excipient were combined and atomized to form our microsphere. Twenty-four male Lanyu pigs weighing 25-30 kg were used. The arteries of spleen and liver were embolized with Gelfoam, Embosphere, or our microsphere. The serum biochemical tests, computed tomography (CT), liver perfusion scan, and tissue microscopy examination were done to evaluate the safety and efficacy of embolization. RESULTS: Radiopaque microspheres with a size ranging from 300 to 400 μm were produced. Embolization of hepatic and splenic artery of pigs with our microsphere significantly reduced the blood flow of liver and resulted in splenic infarction. The follow-up CT imaging and the microscopic examination showed intraarterial degradation of Gelfoam and microsphere. The blood tests demonstrated insignificant changes with regards to liver and renal functions. CONCLUSION: Our microspheres, with the unique characteristics, can be used for transcatheter arterial embolization with effects equivalent to or better than Gelfoam and Embosphere in pigs. PMID:26339465

  12. Performance evaluation of bipolar and tripolar excitations during nozzle-jetting-based alginate microsphere fabrication

    NASA Astrophysics Data System (ADS)

    Herran, C. Leigh; Huang, Yong; Chai, Wenxuan

    2012-08-01

    Microspheres, small spherical (polymeric) particles with or without second phase materials embedded or encapsulated, are important for many biomedical applications such as drug delivery and organ printing. Scale-up fabrication with the ability to precisely control the microsphere size and morphology has always been of great manufacturing interest. The objective of this work is to experimentally study the performance differences of bipolar and tripolar excitation waveforms in using drop-on-demand (DOD)-based single nozzle jetting for alginate microsphere fabrication. The fabrication performance has been evaluated based on the formability of alginate microspheres as a function of materials properties (sodium alginate and calcium chloride concentrations) and operating conditions. The operating conditions for each excitation include voltage rise/fall times, dwell times and excitation voltage amplitudes. Overall, the bipolar excitation is more robust in making spherical, monodispersed alginate microspheres as good microspheres for its wide working range of material properties and operating conditions, especially during the fabrication of highly viscous materials such as the 2% sodium alginate solution. For both bipolar and tripolar excitations, the sodium alginate concentration and the voltage dwell times should be carefully selected to achieve good microsphere formability.

  13. Evaluation of BSA protein release from hollow hydroxyapatite microspheres into PEG hydrogel

    PubMed Central

    Fu, Hailuo; Rahaman, Mohamed N.; Brown, Roger F.; Day, Delbert E.

    2013-01-01

    Implants that simultaneously function as an osteoconductive matrix and as a device for local drug or growth factor delivery could provide an attractive system for bone regeneration. In our previous work, we prepared hollow hydroxyapatite (abbreviated HA) microspheres with a high surface area, mesoporous shell wall and studied the release of a model protein, bovine serum albumin (BSA), from the microspheres into phosphate-buffered saline (PBS). The present work is an extension of our previous work to study the release of BSA from similar HA microspheres into a biocompatible hydrogel, poly(ethylene glycol) (PEG). BSA-loaded HA microspheres were placed in a PEG solution which was rapidly gelled using ultraviolet radiation. The BSA release rate into the PEG hydrogel, measured using a spectrophotometric method, was slower than into PBS, and it was dependent on the initial BSA loading and on the microstructure of the microsphere shell wall. A total of 35–40% of the BSA initially loaded into the microspheres was released into PEG over ~14 days. The results indicate that these hollow HA microspheres have promising potential as an osteoconductive device for local drug or growth factor delivery in bone regeneration and in the treatment of bone diseases. PMID:23498254

  14. An effective way to hydrophilize gigaporous polystyrene microspheres as rapid chromatographic separation media for proteins.

    PubMed

    Qu, Jian-Bo; Zhou, Wei-Qing; Wei, Wei; Su, Zhi-Guo; Ma, Guang-Hui

    2008-12-02

    To overcome the disadvantages of protein denaturation and nonspecific adsorption on poly(styrene-divinylbenzene) (PS) medium as a chromatographic support, gigaporous PS microspheres prepared in our previous study were coated with hydrophobically modified agarose (phenoxyl agarose, Agap). Both the modification of agarose and the gigaporous structure of PS microspheres provided an advantage that facilitated the coating of Agap onto PS microspheres. The amount of Agap adsorbed onto the PS surface was examined as a function of the polymer concentration, and various samples of microspheres, differing in surface Agap density, were prepared. The adsorbed layer was then stabilized by chemical cross-linking and its stability was evaluated in the presence of sodium dodecyl sulfate. Results showed that PS microspheres were successfully coated with Agap, while the gigaporous structure could be well maintained. After coating, the nonspecific adsorption of proteins on PS microspheres was greatly reduced. Flow hydrodynamics experiments showed that the Agap-co-PS column had low backpressure, good permeability, and mechanical stability. Such a procedure could provide a hydrophilic low-pressure liquid chromatographic support for different types of chromatography, since the Agap layer may be easily derivatized by classical methods, and because of their good permeability, the coated microspheres have great potential applications in high-speed protein chromatography.

  15. Continuous theta burst transcranial magnetic stimulation affects brain functional connectivity.

    PubMed

    Dan Cao; Yingjie Li; Ling Wei; Yingying Tang

    2016-08-01

    Prefrontal cortex (PFC) plays an important role in the emotional processing as well as in the functional brain network. Hyperactivity in the right dorsolateral prefrontal cortex (DLPFC) would be found in anxious participants. However, it is still unclear what the role of PFC played in a resting functional network. Continuous theta burst transcranial magnetic stimulation (cTBS) is an effective tool to create virtual lesions on brain regions. In this paper, we applied cTBS over right prefrontal area, and investigated the effects of cTBS on the brain activity for functional connectivity by the method of graph theory. We recorded 64-channels EEG on thirteen healthy participants in the resting condition and emotional tasks before and after 40 s of cTBS. This work focused on the effect of cTBS on cortical activities in the resting condition by calculating the coherence between EEG channels and building functional networks before and after cTBS in the delta, theta, alpha and beta bands. Results revealed that 1) The functional connectivity after cTBS was significantly increased compared with that before cTBS in delta, theta, alpha and beta bands in the resting condition; 2) The efficiency-cost reached the maximum before and after cTBS both with the cost about 0.3 in the bands above, which meant that the information transmission of functional brain network with this cost was highly efficient; 3) the clustering coefficient and path length after cTBS was significantly increased in delta, theta and beta bands. In conclusion, cTBS over PFC indeed enhanced the functional connectivity in the resting condition. In addition, the information transmission in the resting brain network was highly efficient with the cost about 0.3.

  16. Longitudinal Functional Magnetic Resonance Imaging in Animal Models

    PubMed Central

    Silva, Afonso C.; Liu, Junjie V.; Hirano, Yoshiyuki; Leoni, Renata F.; Merkle, Hellmut; Mackel, Julie B.; Zhang, Xian Feng; Nascimento, George C.; Stefanovic, Bojana

    2016-01-01

    Functional magnetic resonance imaging (fMRI) has had an essential role in furthering our understanding of brain physiology and function. fMRI techniques are nowadays widely applied in neuroscience research, as well as in translational and clinical studies. The use of animal models in fMRI studies has been fundamental in helping elucidate the mechanisms of cerebral blood flow regulation, and in the exploration of basic neuroscience questions, such as the mechanisms of perception, behavior, and cognition. Because animals are inherently noncompliant, most fMRI performed to date have required the use of anesthesia, which interferes with brain function and compromises interpretability and applicability of results to our understanding of human brain function. An alternative approach that eliminates the need for anesthesia involves training the animal to tolerate physical restraint during the data acquisition. In the present work we review these two different approaches to obtaining fMRI data from animal models, with a specific focus on the acquisition of longitudinal data from the same subjects. PMID:21279608

  17. Functional magnetic resonance imaging of mild traumatic brain injury.

    PubMed

    Mayer, Andrew R; Bellgowan, Patrick S F; Hanlon, Faith M

    2015-02-01

    Functional magnetic resonance imaging (fMRI) offers great promise for elucidating the neuropathology associated with a single or repetitive mild traumatic brain injury (mTBI). The current review discusses the physiological underpinnings of the blood-oxygen level dependent response and how trauma affects the signal. Methodological challenges associated with fMRI data analyses are considered next, followed by a review of current mTBI findings. The majority of evoked studies have examined working memory and attentional functioning, with results suggesting a complex relationship between cognitive load/attentional demand and neuronal activation. Researchers have more recently investigated how brain trauma affects functional connectivity, and the benefits/drawbacks of evoked and functional connectivity studies are also discussed. The review concludes by discussing the major clinical challenges associated with fMRI studies of brain-injured patients, including patient heterogeneity and variations in scan-time post-injury. We conclude that the fMRI signal represents a complex filter through which researchers can measure the physiological correlates of concussive symptoms, an important goal for the burgeoning field of mTBI research.

  18. Vocal tract area functions from magnetic resonance imaging.

    PubMed

    Story, B H; Titze, I R; Hoffman, E A

    1996-07-01

    There have been considerable research efforts in the area of vocal tract modeling but there is still a small body of information regarding direct 3-D measurements of the vocal tract shape. The purpose of this study was to acquire, using magnetic resonance imaging (MRI), an inventory of speaker-specific, three-dimensional, vocal tract air space shapes that correspond to a particular set of vowels and consonants. A set of 18 shapes was obtained for one male subject who vocalized while being scanned for 12 vowels, 3 nasals, and 3 plosives. The 3-D shapes were analyzed to find the cross-sectional areas evaluated within planes always chosen to be perpendicular to the centerline extending from the glottis to the mouth to produce an "area function." This paper provides a speaker-specific catalogue of area functions for 18 vocal tract shapes. Comparisons of formant locations extracted from the natural (recorded) speech of the imaged subject and from simulations using the newly acquired area functions show reasonable similarity but suggest that the imaged vocal tract shapes may be somewhat centralized. Additionally, comparisons of the area functions reported in this study are compared with those from four previous studies and demonstrate general similarities in shape but also obvious differences that can be attributed to differences in imaging techniques, image processing methods, and anatomical differences of the imaged subjects.

  19. Modulating functional and dysfunctional mentalizing by transcranial magnetic stimulation

    PubMed Central

    Schuwerk, Tobias; Langguth, Berthold; Sommer, Monika

    2014-01-01

    Mentalizing, the ability to attribute mental states to others and oneself, is a cognitive function with high relevance for social interactions. Recent neuroscientific research has increasingly contributed to attempts to decompose this complex social cognitive function into constituting neurocognitive building blocks. Additionally, clinical research that focuses on social cognition to find links between impaired social functioning and neurophysiological deviations has accumulated evidence that mentalizing is affected in most psychiatric disorders. Recently, both lines of research have started to employ transcranial magnetic stimulation: the first to modulate mentalizing in order to specify its neurocognitive components, the latter to treat impaired mentalizing in clinical conditions. This review integrates findings of these two different approaches to draw a more detailed picture of the neurocognitive basis of mentalizing and its deviations in psychiatric disorders. Moreover, we evaluate the effectiveness of hitherto employed stimulation techniques and protocols, paradigms and outcome measures. Based on this overview we highlight new directions for future research on the neurocognitive basis of functional and dysfunctional social cognition. PMID:25477838

  20. Pre-surgical language mapping with functional magnetic resonance imaging.

    PubMed

    Bookheimer, Susan

    2007-06-01

    Patients with lesions in or near eloquent cortex typically undergo one of several invasive techniques to prevent loss of function following surgery. One of the most promising potential clinical applications of functional magnetic resonance imaging (fMRI) is to map these functions as part of the pre-surgical work-up to identify patients at-risk, guide the surgical entry, or tailor the surgical procedure to prevent deficits. While motor and sensory mapping are relatively straightforward, language mapping is far more complex. The language system is variable in location across individuals and in many cases may reorganize partially or completely to the contralateral hemisphere. In addition, multiple regions of the brain contribute to language functioning including essential regions that must not be removed in surgery, and contributory regions that may result in transient or insignificant impairments post-surgery. Despite these challenges, an increasing number of studies have supported the use of fMRI for pre-surgical language mapping in a variety of disorders. This article reviews the literature from three disorders for which patients benefit from preoperative language mapping: epilepsy, brain tumors, and arteriovenous malformations. Each disorder presents unique challenges to language mapping. Specific case studies are presented highlighting the both the potential benefits of preclinical fMRI for language mapping as well as the potential risks and pitfalls.

  1. Beef assessments using functional magnetic resonance imaging and sensory evaluation.

    PubMed

    Tapp, W N; Davis, T H; Paniukov, D; Brooks, J C; Brashears, M M; Miller, M F

    2017-04-01

    Functional magnetic resonance imaging (fMRI) has been used to unveil how some foods and basic rewards are processed in the human brain. This study evaluated how resting state functional connectivity in regions of the human brain changed after differing qualities of beef steaks were consumed. Functional images of participants (n=8) were collected after eating high or low quality beef steaks on separate days, after consumption a sensory ballot was administered to evaluate consumers' perceptions of tenderness, juiciness, flavor, and overall liking. Imaging data showed that high quality steak samples resulted in greater functional connectivity to the striatum, medial orbitofrontal cortex, and insular cortex at various stages after consumption (P≤0.05). Furthermore, high quality steaks elicited higher sensory ballot scores for each palatability trait (P≤0.01). Together, these results suggest that resting state fMRI may be a useful tool for evaluating the neural process that follows positive sensory experiences such as the enjoyment of high quality beef steaks. Published by Elsevier Ltd.

  2. Hyperpolarized Xenon-129 Magnetic Resonance Imaging of Functional Lung Microstructure

    NASA Astrophysics Data System (ADS)

    Dregely, Isabel

    Hyperpolarized 129Xe (HXe) is a non-invasive contrast agent for lung magnetic resonance imaging (MRI), which upon inhalation follows the functional pathway of oxygen in the lung by dissolving into lung tissue structures and entering the blood stream. HXe MRI therefore provides unique opportunities for functional lung imaging of gas exchange which occurs from alveolar air spaces across the air-blood boundary into parenchymal tissue. However challenges in acquisition speed and signal-to-noise ratio have limited the development of a HXe imaging biomarker to diagnose lung disease. This thesis addresses these challenges by introducing parallel imaging to HXe MRI. Parallel imaging requires dedicated hardware. This work describes design, implementation, and characterization of a 32-channel phased-array chest receive coil with an integrated asymmetric birdcage transmit coil tuned to the HXe resonance on a 3 Tesla MRI system. Using the newly developed human chest coil, a functional HXe imaging method, multiple exchange time xenon magnetization transfer contrast (MXTC) is implemented. MXTC dynamically encodes HXe gas exchange into the image contrast. This permits two parameters to be derived regionally which are related to gas-exchange functionality by characterizing tissue-to-alveolar-volume ratio and alveolar wall thickness in the lung parenchyma. Initial results in healthy subjects demonstrate the sensitivity of MXTC by quantifying the subtle changes in lung microstructure in response to orientation and lung inflation. Our results in subjects with lung disease show that the MXTC-derived functional tissue density parameter exhibits excellent agreement with established imaging techniques. The newly developed dynamic parameter, which characterizes the alveolar wall, was elevated in subjects with lung disease, most likely indicating parenchymal inflammation. In light of these observations we believe that MXTC has potential as a biomarker for the regional quantification of 1

  3. Synthesis of fibrous and non-fibrous mesoporous silica magnetic yolk-shell microspheres as recyclable supports for immobilization of Candida rugosa lipase.

    PubMed

    Ali, Zafar; Tian, Lei; Zhang, Baoliang; Ali, Nisar; Khan, Muhammad; Zhang, Qiuyu

    2017-08-01

    The mesoporous yolk-shell nanoparticles (MYSNs), with a movable Fe3O4 core inside the hollow capsules, with two different morphologies (1) Fe3O4@SiO2@hollow@fibrous SiO2 (Yolk Shell-1) (2) Fe3O4@SiO2@hollow@mesoporousSiO2 (Yolk Shell-2) were fabricated as carriers for Candida rugosa lipase (CRL) immobilization, through a template-assistant selectively etching method. Firstly the hydrophilic Fe3O4 nanoparticles were synthesized according to the solvothermal method. Then, SiO2 shell was coated on the Fe3O4 nanoparticle surface by a sol-gel reaction. Subsequently, the resorcinol farmaldehyde (RF) shell was covered on the surface of as-prepared Fe3O4@SiO2 composites and sandwiched Fe3O4@SiO2@RF composites were formed, which were finally provided with mesoporous fibrous (KCC) in the Yolk Shell-1 and mesoporous Silica in the Yolk Shell-2(Non fibrous). After selectively etching CTAB and the middle RF layer, the two kinds of yolk/shells composites were obtained. By utilization of their large and open mesopores (20-50nm) with good surface area (457.78-625.54m(2)/g,) CRL was immobilized after amino functionalization using glutaraldehyde as a linker. The ICRL on Y.S-1, Y.S-2 showed good loading (797-501mg/g) and enzyme activity of (1503-837U/g) respectively. Thermal stability, resistance to pH, recycling and storage capacity were improved as compare to free lipase. Copyright © 2017. Published by Elsevier Inc.

  4. Development of Risperidone PLGA Microspheres

    PubMed Central

    D'Souza, Susan; Faraj, Jabar A.; Giovagnoli, Stefano; DeLuca, Patrick P.

    2014-01-01

    The aim of this study was to design and evaluate biodegradable PLGA microspheres for sustained delivery of Risperidone, with an eventual goal of avoiding combination therapy for the treatment of schizophrenia. Two PLGA copolymers (50 : 50 and 75 : 25) were used to prepare four microsphere formulations of Risperidone. The microspheres were characterized by several in vitro techniques. In vivo studies in male Sprague-Dawley rats at 20 and 40 mg/kg doses revealed that all formulations exhibited an initial burst followed by sustained release of the active moiety. Additionally, formulations prepared with 50 : 50 PLGA had a shorter duration of action and lower cumulative AUC levels than the 75 : 25 PLGA microspheres. A simulation of multiple dosing at weekly or 15-day regimen revealed pulsatile behavior for all formulations with steady state being achieved by the second dose. Overall, the clinical use of Formulations A, B, C, or D will eliminate the need for combination oral therapy and reduce time to achieve steady state, with a smaller washout period upon cessation of therapy. Results of this study prove the suitability of using PLGA copolymers of varying composition and molecular weight to develop sustained release formulations that can tailor in vivo behavior and enhance pharmacological effectiveness of the drug. PMID:24616812

  5. Multifunctionalized biocompatible microspheres for sensing.

    PubMed

    Sánchez-Martín, Rosario M; Alexander, Lois; Bradley, Mark

    2008-01-01

    We present our achievements in the synthesis and application of multifunctionalized, cross-linked, polystyrene microspheres, which remarkably and quite generally are taken up by all cell types studied to date. Importantly, the nature of these synthetic beads allows multistep solid-phase chemistry and the ability to bind essentially any molecule/sensor/nucleic acid to them. These microspheres have a number of advantages over other cellular delivery approaches. First, a diverse range of compounds can be attached to the microspheres, and we have demonstrated that these materials are effectively delivered into cells; second, the cellular cargo can be modulated through modification of bead loading; third, they are large enough to be visualized using standard microscopy techniques; and fourth, their cargos are not diluted within the cell. Populations of cells containing beads can be readily sorted from other cells for subsequent analysis with very high, but controllable, uptake rates, which can be modulated through modulation of the bead size and incubation time. Recent work has focused on the development of these microspheres as sensors for intracellular calcium and pH.

  6. Triphenylamine-functionalized magnetic microparticles as a new adsorbent coupled with high performance liquid chromatography for the analysis of trace polycyclic aromatic hydrocarbons in aqueous samples.

    PubMed

    Long, Yiming; Chen, Yingzhuang; Yang, Fei; Chen, Chunyan; Pan, Di; Cai, Qingyun; Yao, Shouzhuo

    2012-06-07

    Triphenylamine (TPA)-functionalized magnetic microspheres (Fe(3)O(4)/SiO(2)/TPA) were prepared and applied as solid phase extraction (SPE) adsorbents for the analysis of polycyclic aromatic hydrocarbons (PAHs) in environmental samples in combination with high-performance liquid chromatography (HPLC). The magnetic solid-phase extraction (MSPE) conditions affectin