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Pattanaik MS, Varma VB, Cheekati SK, Chaudhary V, Ramanujan RV. Optimal ferrofluids for magnetic cooling devices. Sci Rep 2021; 11:24167. [PMID: 34921195 PMCID: PMC8683428 DOI: 10.1038/s41598-021-03514-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 11/30/2021] [Indexed: 11/25/2022] Open
Abstract
Superior passive cooling technologies are urgently required to tackle device overheating, consequent performance degradation, and service life reduction. Magnetic cooling, governed by the thermomagnetic convection of a ferrofluid, is a promising emerging passive heat transfer technology to meet these challenges. Hence, we studied the performance metrics, non-dimensional parameters, and thermomagnetic cooling performance of various ferrite and metal-based ferrofluids. The magnetic pressure, friction factor, power transfer, and exergy loss were determined to predict the performance of such cooling devices. We also investigated the significance of the magnetic properties of the nanoparticles used in the ferrofluid on cooling performance. γ-Fe2O3, Fe3O4, and CoFe2O4 nanoparticles exhibited superior cooling performance among ferrite-based ferrofluids. FeCo nanoparticles had the best cooling performance for the case of metallic ferrofluids. The saturation magnetization of the magnetic nanoparticles is found to be a significant parameter to enhance heat transfer and heat load cooling. These results can be used to select the optimum magnetic nanoparticle-based ferrofluid for a specific magnetic cooling device application.
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Affiliation(s)
- M. S. Pattanaik
- grid.59025.3b0000 0001 2224 0361School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798 Singapore ,grid.499358.aSingapore-HUJ Alliance for Research and Enterprise (SHARE), Nanomaterials for Energy and Energy-Water Nexus (NEW), Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, 138602 Singapore
| | - V. B. Varma
- grid.59025.3b0000 0001 2224 0361School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798 Singapore ,grid.499358.aSingapore-HUJ Alliance for Research and Enterprise (SHARE), Nanomaterials for Energy and Energy-Water Nexus (NEW), Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, 138602 Singapore
| | - S. K. Cheekati
- grid.59025.3b0000 0001 2224 0361School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798 Singapore ,grid.499358.aSingapore-HUJ Alliance for Research and Enterprise (SHARE), Nanomaterials for Energy and Energy-Water Nexus (NEW), Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, 138602 Singapore
| | - V. Chaudhary
- grid.59025.3b0000 0001 2224 0361School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798 Singapore
| | - R. V. Ramanujan
- grid.59025.3b0000 0001 2224 0361School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798 Singapore ,grid.499358.aSingapore-HUJ Alliance for Research and Enterprise (SHARE), Nanomaterials for Energy and Energy-Water Nexus (NEW), Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, 138602 Singapore
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Iravani S. Bio-Based Synthesis of Magnetic Nanoparticles and Their Applications. NANOTECHNOLOGY IN THE LIFE SCIENCES 2019. [DOI: 10.1007/978-3-030-16439-3_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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3
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Liu Y, Li G. A power-free, parallel loading microfluidic reactor array for biochemical screening. Sci Rep 2018; 8:13664. [PMID: 30209328 PMCID: PMC6135844 DOI: 10.1038/s41598-018-31720-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 08/24/2018] [Indexed: 12/25/2022] Open
Abstract
This paper presents a power-free, self-contained microfluidic device in which a number of nanoliter-sized droplets can be parallelly and accurately metered and mixed for high-throughput analysis and/or portable systems. In this system, the absorption of air by pre-degassed PDMS and the change of capillary force due to sudden narrowing of the channel cross-section provide the mechanism for actuating, metering and mixing the flow of fluid in the microfluidic channels and chambers. With an array of channels and capillary valves combined with an array of pre-degassed PDMS pump chambers, the device can perform multiple liquid dispensing and mixing in parallel, and its performance and reproducibility are also evaluated. As a practical application, the proposed device is used to screen crystallization conditions of lysozyme. This device needs neither external power nor complex instruments for fluid handling. Thus, it offers an easy-to-use, inexpensive and power-free way to perform multiple nanoliter-volume distinct reactions in parallel format and should be ideally suitable for individual laboratories for various applications such as enzyme assay, protein crystallization, drug discovery, and combinatorial chemistry.
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Affiliation(s)
- Yanwu Liu
- College of Stomatology, Chongqing Medical University, Chongqing, 401147, China
| | - Gang Li
- Defense Key Disciplines Lab of Novel Micro-Nano Devices and System Technology, Key Laboratory of Optoelectronic Technology and Systems, Ministry of Education, Chongqing University, Chongqing, 400044, China.
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Chaudhary V, Ramanujan R. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling. Sci Rep 2016; 6:35156. [PMID: 27725754 PMCID: PMC5057077 DOI: 10.1038/srep35156] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/26/2016] [Indexed: 11/09/2022] Open
Abstract
Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100-xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg-1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.
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Affiliation(s)
- V. Chaudhary
- Interdisciplinary Graduate School (IGS), Nanyang Technological University, Singapore 639798, Singapore
- Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, Singapore 637553, Singapore
- School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - R.V. Ramanujan
- School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798, Singapore
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Bacteria in Nanoparticle Synthesis: Current Status and Future Prospects. INTERNATIONAL SCHOLARLY RESEARCH NOTICES 2014; 2014:359316. [PMID: 27355054 PMCID: PMC4897565 DOI: 10.1155/2014/359316] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 07/09/2014] [Accepted: 08/04/2014] [Indexed: 11/17/2022]
Abstract
Microbial metal reduction can be a strategy for remediation of metal contaminations and wastes. Bacteria are capable of mobilization and immobilization of metals and in some cases, the bacteria which can reduce metal ions show the ability to precipitate metals at nanometer scale. Biosynthesis of nanoparticles (NPs) using bacteria has emerged as rapidly developing research area in green nanotechnology across the globe with various biological entities being employed in synthesis of NPs constantly forming an impute alternative for conventional chemical and physical methods. Optimization of the processes can result in synthesis of NPs with desired morphologies and controlled sizes, fast and clean. The aim of this review is, therefore, to make a reflection on the current state and future prospects and especially the possibilities and limitations of the above mentioned bio-based technique for industries.
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Soroori S, Kulinsky L, Kido H, Madou M. Design and implementation of fluidic micro-pulleys for flow control on centrifugal microfluidic platforms. MICROFLUIDICS AND NANOFLUIDICS 2014; 16:1117-1129. [PMID: 25328508 PMCID: PMC4196217 DOI: 10.1007/s10404-013-1277-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Microfluidic discs have been employed in a variety of applications for chemical analyses and biological diagnostics. These platforms offer a sophisticated fluidic toolbox, necessary to perform processes that involve sample preparation, purification, analysis, and detection. However, one of the weaknesses of such systems is the uni-directional movement of fluid from the disc center to its periphery due to the uni-directionality of the propelling centrifugal force. Here we demonstrate a mechanism for fluid movement from the periphery of a hydrophobic disc toward its center that does not rely on the energy supplied by any peripheral equipment. This method utilizes a ventless fluidic network that connects a column of working fluid to a sample fluid. As the working fluid is pushed by the centrifugal force to move toward the periphery of the disc, the sample fluid is pulled up toward the center of the disc analogous to a physical pulley where two weights are connected by a rope passed through a block. The ventless network is analogous to the rope in the pulley. As the working fluid descends, it creates a negative pressure that pulls the sample fluid up. The sample and working fluids do not come into direct contact and it allows the freedom to select a working fluid with physical properties markedly different from those of the sample. This article provides a demonstration of the "micro-pulley" on a disc, discusses underlying physical phenomena, provides design guidelines for fabrication of micro-pulleys on discs, and outlines a vision for future micro-pulley applications.
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Affiliation(s)
- Salar Soroori
- Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
- Corresponding author: , Tel. +1-949-824-1225
| | - Lawrence Kulinsky
- Department of Mechanical & Aerospace Engineering, University of California, Irvine, CA, 92697, USA
| | - Horacio Kido
- Department of Mechanical & Aerospace Engineering, University of California, Irvine, CA, 92697, USA
- RotaPrep, Inc., Tustin, CA, 92782, USA
| | - Marc Madou
- Department of Biomedical Engineering, University of California, Irvine, CA, 92697, USA
- Department of Mechanical & Aerospace Engineering, University of California, Irvine, CA, 92697, USA
- UNIST, World Class University (WCU), Ulsan, South Korea
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Yang X, Tschulik K, Uhlemann M, Odenbach S, Eckert K. Enrichment of Paramagnetic Ions from Homogeneous Solutions in Inhomogeneous Magnetic Fields. J Phys Chem Lett 2012; 3:3559-3564. [PMID: 26290988 DOI: 10.1021/jz301561q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Applying interferometry to an aqueous solution of paramagnetic manganese ions, subjected to an inhomogeneous magnetic field, we observe an unexpected but highly reproducible change in the refractive index. This change occurs in the top layer of the solution, closest to the magnet. The shape of the layer is in accord with the spatial distribution of the largest component of the magnetic field gradient force. It turns out that this layer is heavier than the underlying solution because it undergoes a Rayleigh-Taylor instability upon removal of the magnet. The very good agreement between the magnitudes of buoyancy, associated with this layer, and the field gradient force at steady state provides conclusive evidence that the layer formation results from an enrichment of paramagnetic manganese ions in regions of high magnetic field gradient.
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Affiliation(s)
- Xuegeng Yang
- †Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, Technische Universität Dresden, D-01069 Dresden, Germany
| | | | | | - Stefan Odenbach
- †Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Kerstin Eckert
- †Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, Technische Universität Dresden, D-01069 Dresden, Germany
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Zhu T, Cheng R, Lee SA, Rajaraman E, Eiteman MA, Querec TD, Unger ER, Mao L. Continuous-flow Ferrohydrodynamic Sorting of Particles and Cells in Microfluidic Devices. MICROFLUIDICS AND NANOFLUIDICS 2012; 13:645-654. [PMID: 26430394 PMCID: PMC4587988 DOI: 10.1007/s10404-012-1004-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A new sorting scheme based on ferrofluid hydrodynamics (ferrohydrodynamics) was used to separate mixtures of particles and live cells simultaneously. Two species of cells, including Escherichia coli and Saccharomyces cerevisiae, as well as fluorescent polystyrene microparticles were studied for their sorting throughput and efficiency. Ferrofluids are stable magnetic nanoparticles suspensions. Under external magnetic fields, magnetic buoyancy forces exerted on particles and cells lead to size-dependent deflections from their laminar flow paths and result in spatial separation. We report the design, modeling, fabrication and characterization of the sorting device. This scheme is simple, low-cost and label-free compared to other existing techniques.
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Affiliation(s)
- Taotao Zhu
- Department of Chemistry, Nanoscale Science and Engineering Center, The University of Georgia, Athens, Georgia 30602, USA
| | - Rui Cheng
- Faculty of Engineering, Nanoscale Science and Engineering Center, The University of Georgia, Athens, Georgia 30602, USA
| | - Sarah A. Lee
- Center for Molecular BioEngineering, Department of Biological and Agricultural Engineering, The University of Georgia, Athens, Georgia 30602, USA
| | - Eashwar Rajaraman
- Center for Molecular BioEngineering, Department of Biological and Agricultural Engineering, The University of Georgia, Athens, Georgia 30602, USA
| | - Mark A. Eiteman
- Center for Molecular BioEngineering, Department of Biological and Agricultural Engineering, The University of Georgia, Athens, Georgia 30602, USA
| | - Troy D. Querec
- Chronic Viral Diseases Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases Pathology, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA
| | - Elizabeth R. Unger
- Chronic Viral Diseases Branch, Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases Pathology, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA
| | - Leidong Mao
- Faculty of Engineering, Nanoscale Science and Engineering Center, The University of Georgia, Athens, Georgia 30602, USA
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Patel R. Effect of temperature on rotational viscosity in magnetic nano fluids. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2012; 35:109. [PMID: 23096152 DOI: 10.1140/epje/i2012-12109-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 07/05/2012] [Accepted: 09/25/2012] [Indexed: 06/01/2023]
Abstract
Flow behavior of magnetic nano fluids with simultaneous effect of magnetic field and temperature is important for its application for cooling devices such as transformer, loud speakers, electronic cooling and for its efficiency in targeted drug delivery and hyperthermia treatment. Using a specially designed horizontal capillary viscometer, temperature-sensitive and non-temperature-sensitive magnetic nano fluids are studied. In both these case the temperature-dependent rotational viscosity decreases, but follows a quite different mechanism. For temperature-sensitive magnetic nano fluids, the reduction in rotational viscosity is due to the temperature dependence of magnetization. Curie temperature ((T)(c)) and pyromagnetic coefficient are extracted from the study. A fluid with low T(c) and high pyromagnetic coefficient is useful for thermo-sensitive cooling devices and magnetic hyperthermia. For non-temperature-sensitive magnetic nano fluids, reduction in rotational viscosity is due to removal of physisorbed secondary surfactant on the particle because of thermal and frictional effects. This can be a good analogy for removal of drug from the magnetic particles in the case of targeted drug delivery.
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Affiliation(s)
- R Patel
- Department of Physics, Sardar Vallabhbhai Patel Campus, Bhavnagar University, 364022, Bhavnagar, GJ, India.
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10
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Fang M, Ström V, Olsson RT, Belova L, Rao KV. Particle size and magnetic properties dependence on growth temperature for rapid mixed co-precipitated magnetite nanoparticles. NANOTECHNOLOGY 2012; 23:145601. [PMID: 22433909 DOI: 10.1088/0957-4484/23/14/145601] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Magnetite nanoparticles have been prepared by co-precipitation using a custom-designed jet mixer to achieve rapid mixing (RM) of reactants in a timescale of milliseconds. The quick and stable nucleation obtained allows control of the particle size and size distribution via a more defined growth process. Nanoparticles of different sizes were prepared by controlling the processing temperature in the first few seconds post-mixing. The average size of the nanoparticles investigated using a Tecnai transmission electron microscope is found to increase with the temperature from 3.8 nm at 1 ± 1 °C to 10.9 nm for particles grown at 95 ± 1 °C. The temperature dependence of the size distribution follows the same trend and is explained in terms of Ostwald ripening of the magnetite nanoparticles during the co-precipitation of Fe(2+) and Fe(3+). The magnetic properties were studied by monitoring the blocking temperature via both DC and AC techniques. Strikingly, the obtained RM particles maintain the high magnetization (as high as ∼88 A m(2) kg(-1) at 500 kA m(-1)) while the coercivity is as low as ∼12 A m(-1) with the expected temperature dependence. Besides, by adding a drop of tetramethylammonium hydroxide, aqueous ferrofluids with long term stability are obtained, suggesting their suitability for applications in ferrofluid technology and biomedicine.
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Affiliation(s)
- Mei Fang
- Department of Materials Science and Engineering, KTH-Royal Institute of Technology, Stockholm SE 10044, Sweden
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11
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Li G, Luo Y, Chen Q, Liao L, Zhao J. A "place n play" modular pump for portable microfluidic applications. BIOMICROFLUIDICS 2012; 6:14118-1411816. [PMID: 22685507 PMCID: PMC3370398 DOI: 10.1063/1.3692770] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Accepted: 02/21/2012] [Indexed: 05/07/2023]
Abstract
This paper presents an easy-to-use, power-free, and modular pump for portable microfluidic applications. The pump module is a degassed particle desorption polydimethylsiloxane (PDMS) slab with an integrated mesh-shaped chamber, which can be attached on the outlet port of microfluidic device to absorb the air in the microfluidic system and then to create a negative pressure for driving fluid. Different from the existing monolithic degassed PDMS pumps that are generally restricted to limited pumping capacity and are only compatible with PDMS-based microfluidic devices, this pump can offer various possible configures of pumping power by varying the geometries of the pump or by combining different pump modules and can also be employed in any material microfluidic devices. The key advantage of this pump is that its operation only requires the user to place the degassed PDMS slab on the outlet ports of microfluidic devices. To help design pumps with a suitable pumping performance, the effect of pump module geometry on its pumping capacity is also investigated. The results indicate that the performance of the degassed PDMS pump is strongly dependent on the surface area of the pump chamber, the exposure area and the volume of the PDMS pump slab. In addition, the initial volume of air in the closed microfluidic system and the cross-linking degree of PDMS also affect the performance of the degassed PDMS pump. Finally, we demonstrated the utility of this modular pumping method by applying it to a glass-based microfluidic device and a PDMS-based protein crystallization microfluidic device.
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12
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Temperature sensitive ferrofluid composed of Mn1−xZnxFe2O4 nanoparticles prepared by a modified hydrothermal process. POWDER TECHNOL 2012. [DOI: 10.1016/j.powtec.2011.10.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Lyubina J, Schäfer R, Martin N, Schultz L, Gutfleisch O. Novel design of La(Fe,Si)13 alloys towards high magnetic refrigeration performance. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:3735-3739. [PMID: 20512813 DOI: 10.1002/adma.201000177] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Julia Lyubina
- Institute for Metallic Materials, IFW Dresden, PO Box 270116, 01171 Dresden, Germany.
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14
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Large-scale production of magnetic nanoparticles using bacterial fermentation. J Ind Microbiol Biotechnol 2010; 37:1023-31. [DOI: 10.1007/s10295-010-0749-y] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 05/20/2010] [Indexed: 10/19/2022]
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15
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Korbekandi H, Iravani S, Abbasi S. Production of nanoparticles using organisms. Crit Rev Biotechnol 2009; 29:279-306. [DOI: 10.3109/07388550903062462] [Citation(s) in RCA: 200] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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16
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Moon JW, Roh Y, Yeary LW, Lauf RJ, Rawn CJ, Love LJ, Phelps TJ. Microbial formation of lanthanide-substituted magnetites by Thermoanaerobacter sp. TOR-39. Extremophiles 2007; 11:859-67. [PMID: 17673945 DOI: 10.1007/s00792-007-0102-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 06/18/2007] [Indexed: 10/23/2022]
Abstract
The potentially toxic effects of soluble lanthanide (L) ions, although microbially induced mineralization can facilitate the formation of tractable materials, has been one factor preventing the more widespread use of L-ions in biotechnology. Here, we propose a new mixed-L precursor method as compared to the traditional direct addition technique. L (Nd, Gd, Tb, Ho and Er)-substituted magnetites, L( y )Fe(3 - y )O(4) were microbially produced using L-mixed precursors, L( x )Fe(1 - x )OOH, where x = 0.01-0.2. By combining lanthanides into the akaganeite precursor phase, we were able to mitigate some of the toxicity, enabling the microbial formation of L-substituted magnetites using a metal reducing bacterium, Thermoanaerobacter sp. TOR-39. The employment of L-mixed precursors enabled the microbial formation of L-substituted magnetite, nominal composition up to L(0.06)Fe(2.94)O(4), with at least tenfold higher L-concentration than could be obtained when the lanthanides were added as soluble salts. This mixed-precursor method can be used to extend the application of microbially produced L-substituted magnetite, while also mitigating their toxicity.
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Affiliation(s)
- Ji-Won Moon
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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Moon JW, Roh Y, Lauf RJ, Vali H, Yeary LW, Phelps TJ. Microbial preparation of metal-substituted magnetite nanoparticles. J Microbiol Methods 2007; 70:150-8. [PMID: 17532071 DOI: 10.1016/j.mimet.2007.04.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Revised: 04/03/2007] [Accepted: 04/13/2007] [Indexed: 10/23/2022]
Abstract
A microbial process that exploits the ability of iron-reducing microorganisms to produce copious amounts of extra-cellular metal (M)-substituted magnetite nanoparticles using akaganeite and dopants of dissolved form has previously been reported. The objectives of this study were to develop methods for producing M-substituted magnetite nanoparticles with a high rate of metal substitution by biological processes and to identify factors affecting the production of nano-crystals. The thermophilic and psychrotolerant iron-reducing bacteria had the ability to form M-substituted magnetite nano-crystals (M(y)Fe(3-y)O(4)) from a doped precursor, mixed-M iron oxyhydroxide, (M(x)Fe(1-x)OOH, x< or =0.5, M is Mn, Zn, Ni, Co and Cr). Within the range of 0.01< or =x< or =0.3, using the mixed precursor material enabled the microbial synthesis of more heavily substituted magnetite compared to the previous method, in which the precursor was pure akaganeite and the dopants were present as soluble metal salts. The mixed precursor method was especially advantageous in the case of toxic metals such as Cr and Ni. Also this new method increased the production rate and magnetic properties of the product, while improving crystallinity, size control and scalability.
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Affiliation(s)
- Ji-Won Moon
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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Mao L, Koser H. Towards ferrofluidics for μ-TAS and lab on-a-chip applications. NANOTECHNOLOGY 2006; 17:S34-S47. [PMID: 21727352 DOI: 10.1088/0957-4484/17/4/007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this paper, we show that ferrofluids can be pumped very effectively in closed-channel geometries both in the macro- and micro-scales using spatially travelling, sinusoidally time-varying magnetic fields. The results from numerical modelling demonstrate that the optimum pumping frequency is the reciprocal of the Brownian relaxation time constant of the magnetic nanoparticles inside the ferrofluid. Since the Brownian time constant depends in part on the overall hydrodynamic volume of the magnetic nanoparticles, this work has been carried with a view to developing functionalized ferrofluids that can be used as sensitive pathogen detectors in the context of ferrohydrodynamic pumping via travelling magnetic fields. A micro-ferrofluidic device has been designed and fabricated in order to demonstrate the potential development of this technology for pathogen detection. A cost-effective fabrication process combining insulated metal substrate etching and soft lithography is used to realize the prototype micro-ferrofluidic device. Results show good agreement between simulation and experiment. We finally propose a ferrofluid-based pathogen detection scheme that is expected to be insensitive to temperature and viscosity differences between the ferrofluid and the sample to be tested.
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Affiliation(s)
- Leidong Mao
- Department of Electrical Engineering, Yale University, 15 Prospect Street, New Haven, CT 06520, USA
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Abstract
Magnetic forces are now being utilised in an amazing variety of microfluidic applications. Magnetohydrodynamic flow has been applied to the pumping of fluids through microchannels. Magnetic materials such as ferrofluids or magnetically doped PDMS have been used as valves. Magnetic microparticles have been employed for mixing of fluid streams. Magnetic particles have also been used as solid supports for bioreactions in microchannels. Trapping and transport of single cells are being investigated and recently, advances have been made towards the detection of magnetic material on-chip. The aim of this review is to introduce and discuss the various developments within the field of magnetism and microfluidics.
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Affiliation(s)
- Nicole Pamme
- National Institute for Materials Science (NIMS), International Centre for Young Scientists (ICYS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
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