Magnetic Separation Method Research Articles

Effect of microwave heating on magnetic separation: Kesikkpr magnetite deposits in Ankara, Central Turkey

In this study, the effect of microwave heating on magnetic separation of the iron ore of magnetite from Kesikkopru (Bala-Ankara, Central Turkey) was investigated. The investigation was based on understanding the enrichment factor differences of magnetic separation and microwave+magnetic separation methods. Only five fractions of magnetite ore display high level of enrichment by using magnetic separation. The optimum results (98.11% enrichment, 63.14% grade for iron) were captured on 150 x 106 µm grain sizes and 0.8 Tesla magnetic field intensity. On the other hand, optimum results (96.99% enrichment, 67.81% grade for iron, 180 watt energy consumption) were hold on three different grain size of ore by using microwave+magnetic separation method. On this method, to get high enrichments, the ore has to be pre-treated for 5 to 7 min on microwave heating. It has been realized that the grade of iron were increased by 3 to 5% for microwave+magnetic when compared to sole magnetic separation. Key words: Magnetite, microwave heating, magnetic separation, Kesikkopru, Turkey.

Gold nanoparticle-based inductively coupled plasma mass spectrometry amplification and magnetic separation for the sensitive detection of a virus-specific RNA sequence

We have developed a sensitive gold nanoparticle (AuNP)-based inductively coupled plasma mass spectrometry (ICP-MS) amplification and magnetic separation method for the detection of oligonucleotide sequences. The assay relies on (i) the sandwich-type binding of two designed probe sequences that specifically recognize the target oligonucleotide sequences, (ii) magnetic bead separation, and (iii) AuNP-based ICP-MS amplification detection. To enhance the analytical signal and minimize the background signal resulting from nonspecific binding, we performed a series of experiments to evaluate the effects of various parameters (the concentration of the capture probe; the time required for hybridization; the number of washings required to eliminate nonspecific binding) on the oligonucleotide detection. Under the optimized conditions, the detection limit was 80 zmol (corresponding to 1.6 fM of the target sequence in a sample volume of 50 μL). Moreover, it employs a shorter hybridization step and ICP-MS, this procedure is relatively simple and rapid (ca. 1.5 h). Based on the analytical results obtained using complementary and mismatched sequences, our method exhibits good performance in distinguishing complementary and random oligonucleotides. Compared with the “gold standard” methodology (plaque assay) for the quantification of dengue virus, our method has the capability to allow early detection of dengue virus in complicated and small-volume samples, with high specificity, good analytical sensitivity, and superior time-effectiveness.

Adsorption of Eu(III) on iron oxide/multiwalled carbon nanotube magnetic composites

Iron oxide/multiwalled carbon nanotube magnetic composites (denoted as magnetic composites) were synthesized and characterized in detail. The magnetic composites can be separated from aqueous solution easily by using magnetic separation method. The application of magnetic composites in the removal of Eu(III) from large volumes of aqueous solutions was studied. The results indicated that the sorption of Eu(III) on the magnetic composites was strongly dependent on pH values and weakly dependent on ionic strength. The sorption of Eu(III) on the magnetic composites was mainly dominated by inner-sphere surface complexation. The linear sorption isotherms of Eu(III) suggested that Eu(III) sorption on the magnetic composites was far from saturation. The large sorption capacity and the easy magnetic separation method indicate that the magnetic composites may be a promising suitable material in nuclear waste management in future.

329 GENETIC TARGETING OF THE PORCINE α1,3-GALACTOSYLTRANSFERASE GENE IN FETAL FIBROBLAST CELLS USING ZINC FINGER NUCLEASES

Hyperacute rejection after porcine-to-human xenotransplantation is caused by binding of preformed human antibodies against Gal-epitopes on the surface of porcine cells. Organs from Gal-negative pigs have shown prolonged survival after transplantation into baboons. Knocking out a gene by conventional gene targeting frequency is extremely inefficient (homologous recombination = 0.0001 to 0.001%; Denning et al. 2001). Recent publications in rats (Geurts et al. 2009) show that the gene knockout via zinc finger nuclease (ZFN)-driven nonhomologous end joining (NHEJ) can be enhanced 10 000-fold over conventional approaches, making it feasible to generate a biallelic gene knockout with one ZFN application. Here, we used ZFN technology to generate porcine cells that carry a ZFN-mediated knockout of the Gal gene to use these cells as donor cells in somatic cell nuclear transfer (SCNT) to obtain live offspring. One primary porcine fetal fibroblast cell line was transfected by electroporation (n = 6) with a pair of ZFN plasmids designed to target the DNA sequence encoding the catalytic domain located in exon 9 of the α1,3-gal locus. Transfected cells were incubated (7 days at a combination of 30°C and 37°C) and analysed for Gal expression by fluorescence activated cell sorting (FACS) using fluorescein isothiocyanate (FITC)-conjugated isolectin-B4. On average, 1.4% (± 0.3%; n = 6) of the cells were free of Gal epitopes, indicating a biallelic knockout. DNA mutation detection analysis (Cel-I assay) of cell cultures gave a mean frequency of 3.5% NHEJ (± 1.3%; n = 6) giving the fraction of mutant alleles within the cell population. One cell line with 1% Gal-negative cells was sorted by a magnetic Dynabead-based separation method to select for Gal-negative cells (Fujimura et al. 2008). Because of the limited amount of Gal-negative cells within the cell population, we chose to select the cells with magnetic beads. This method is gentler to the cells and leads to a higher plating efficiency after sorting compared with FACS. The sorted cells could be easily expanded and will serve as donor cells in SCNT to show the feasibility of generating knockout pigs via ZFN-mediated gene knockout. This study demonstrates that ZFN technology is an applicable tool to produce genetically modified porcine cells for use as donors in SCNT and to speed the creation of pig models for xenotransplantation and human diseases.

A simple magnetic separation method for high-yield isolation of pure primary microglia

Microglial cells play a dynamic role in the brain beyond their established function of immune surveillance. Activated microglia play key roles in neural development, neuroinflammation, neural repair and neurotoxicity. They are particularly important in several neurodegenerative diseases in which sustained microglial activation contributes to the progression of neurodegenerative processes. Consequently, understanding microglial function in CNS health and disease has become an area of active research in recent years. However, a significant obstacle to progress in this field has been the inherent difficulties in obtaining large amounts of primary microglial cells to routinely perform mechanistic studies and characterize signaling pathways regulating the dynamics of microglial activation. Herein, we describe a novel column-free magnetic separation protocol for high-yield isolation of primary microglia from mouse postnatal mixed glial cultures. The procedure is based on optimized culture conditions that enable high microglial cell densities in confluent mixed glial cultures followed by highly efficient recovery of pure microglia by magnetic separation. The novel column-free magnetic separation system utilizes tetrameric antibody complexes (TAC) with dual specificity for CD11b-PE labeled microglia and dextran magnetic nanoparticles. An FcR blocker (anti-CD16/32) is added to enhance the purity of the microglial separation by preventing non-specific labeling of other cell types. This procedure yields on average >3×106 microglial cells per mouse pup, with a remarkable purity of 97% and recovery of around 87% of microglia from the mixed glial population. Importantly, the microglia obtained by this method are fully functional and respond like cells obtained by conventional isolation techniques.

Rapid and highly sensitive detection of Flavobacterium psychrophilum using high gradient immunomagnetic separation with flow cytometry

The bacterial cold water disease caused by Flavobacterium psychrophilum is a concern not only for the aquaculture industry, but also the environment. We developed a novel method for detecting F. psychrophilum using high gradient magnetic separation (HGMS) with flow cytometry (FCM). HGMS is a magnetic separation method in which the magnetic force is strengthened by introducing a magnetic gradient between the magnetic filter and nearby column. F. psychrophilum cells that had reacted with immunomagnetic beads were loaded onto the column containing the magnetic filters. When the column was placed inside a neodymium ring magnet, the cells became stuck to the magnetic filters. When magnetic separation of a 500 ml sample was performed, more than 80% of the beads were trapped by the magnetic filter. The collected cells were easily removed from the filter by turning off the magnetic field. The cells were reacted with fluorescein isothiocyanate-labeled antibody, and then fluorescence was measured using FCM. The detection sensitivity was three orders of magnitude higher than that of an FCM assay without HGMS. The cell numbers determined by FCM correlated with those obtained using the colony counting method in the range of approximately 10 1–10 5 colony forming units per milliliter. One FCM assay could be completed within 60 s and the total assay time, including sample preparation, was less than 2.5 h. The proposed method using HGMS and FCM allows for rapid and highly sensitive detection of F. psychrophilum.

Studies on the interactions of fluorescent-magnetic nanocomposites with biomolecules and cells labeling

In this study, the fluorescent-magnetic nanocomposites were synthesized. The interactions between nanocomposites and bovine serum albumin (BSA) were studied by absorption and FL titration experiments. The experiments show that binding of nanocomposites and BSA may be caused by the formation of QDs–BSA complex. A magnetic separation method was designed to directly demonstrate the interactions between the surface of bifunctional nanocomposites with CdSe/CdS quantum dots (QDs) and biomolecules (BSA and DNA). The fluorescence (FL) labeling on the Escherchia coli ( E. coli) cells was also successfully developed for studying the biolabeling of the bifunctional nanocomposites. The results directly reveal that the bifunctional nanocomposites can separate biomolecules and label cells. The studies we have performed showed that the fluorescent-magnetic nanocomposites are proved to be a kind of novel biofuctional materials, which can be used in bioseparation and biolabeling applications.

Magnetic separation technique for environmental water purification by strong magnetic field generator loading HTS bulk magnets

The magnetic separation technique in combination with high temperature superconducting bulk magnets has been investigated to purify the ground water which has been used in the coolant system for the incinerator furnace to cool the burning gas. The experiment has been operated by means of the newly-built alternating channel type magnetic separating device. The separation ratios of ferromagnetic flocks including fine magnetite powder have been estimated by means of the high gradient magnetic separation method with small iron balls filled in the water channels. As the magnetic force acting on the magnetic particle is given by the product of a magnetization of the material and a gradient of magnetic field, and as the ferromagnetic stainless steel balls yield the steep gradient of magnetic field around them in a strong magnetic field, the system has exhibited a quite excellent performance with respect to the separation ratios. The separation ratios of the flocks which contain the magnetite powder with the values more than 50ppm have remained over 80% for under the flow rates less than 5L/min.

Abstract 3469: Effect of age and mutagen on the enriched murine mammary epithelial stem and progenitor cell population

Abstract Epidemiological studies indicated that aging is a significant risk factor for breast cancer. Yet, there is insufficient knowledge on the mechanisms affecting breast cancer initiation and promotion in older women. Recent studies indicated epithelial stem/progenitor cell population, responsible for lifelong tissue maintenance and regeneration, as a target of transformation. It has been reported earlier by serial transplantation of murine mammary tissues that functional mammary outgrowths indicating stem cell function is unaffected by the age of the donor. But it is unclear that whether spontaneous or induced mutagenesis in the aging stem/progenitor cell population has the potential to impair stem/progenitor functions and/or to initiate tumorigenesis. In this study, first we have isolated lineage negative (CD31−CD45−Ter119−) mammary epithelial cells (Lin−MEC) from the thoracic/inguinal mammary glands of young (6 months, n=7) and old (28 months, n=6) mice by serial enzymatic dissociation followed by magnetic nanoparticle separation method (StemCell Technology). These cells were utilized to form mammospheres, representing mammary stem/early progenitor cells. Although the frequency of mammosphere formation remained the same, the number of larger mammospheres (>60µm) from old mice were significantly lower than the young mice, probably indicating decreased stem cell activity in the older population. To study the effect of mutagen in vivo, we treated two young and two old mice with methyl nitrosourea (MNU, 25mg/kg body weight) once a week for three consecutive weeks. Animals were sacrificed one week after the last treatment. Both total and larger mammospheres (>60µm) from the isolated Lin−MEC of the treated older mice were observed in significantly higher number than the treated younger mice. In a recent clinical study larger mammospheres (>50µm) obtained from metastatic breast cancer cells has been correlated to their ability to induce tumors. These Lin−MEC cells were also analyzed and compared for DNA damage by alkaline comet assay and a higher percentage of cells (>10%) with irreversible DNA damage in the older population were observed compared to younger population (<2%) indicating probable lower DNA repair capacity of the former cells. Thus, our preliminary study indicated that enriched stem/progenitor cells in the old mice with decreased in vitro stem cell activity might have the potential to be vulnerable to DNA damage by mutagens and subsequent tumorigenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3469.

Separation, characterization and initial reaction studies of magnetite particles from Hanford sediments

Magnetic and density separation methods have been applied to composite sediment samples from the Hanford formation from sediment recovered during drilling of an uncontaminated borehole located near the 200 West Area of the Hanford Site in southeastern Washington State. This paper describes the results of using those separation methods and from the characterization and initial reactivity measurements on a highly magnetic fraction isolated from that sediment. X-ray diffraction (XRD) analysis of the highly magnetic sediment fraction indicates that this material contains predominantly magnetite (Fe 3O 4). Particle morphology observed by scanning electron microscopy (SEM) and compositions determined energy dispersive spectroscopy (EDS) are consistent with this identification. Analyses by X-ray photoelectron spectroscopy (XPS) indicates that there is a thin coating on the particles that are likely a type of aluminosilicate. This highly magnetic fraction of material is not reactive with indigo carmine, an organic redox probe molecule that was shown to readily react with synthetic magnetite. Because of the limited amounts of material readily available, initial tests have been conducted that demonstrate the ability to complete U(VI) sorption on individual particles (nominally ∼100 μm in size) of the isolated sediment and to remove and mount these individual particles for analysis of the concentration and chemical state of the sorbed U species using small area XPS.

Mesenchymal Stem Cells Convert Human Macrophages to a Novel Type of Alternatively Activated Macrophages.

Abstract 3632Poster Board III-568Mesenchymal stem cells (MSCs) are capable of modulating the immune system through interaction with a wide range of immune cells. This study investigates the hypothesis that interaction of MSCs with macrophages could play a significant role in their anti-inflammatory/immune modulatory effects. All studies were approved by IRB of University of Wisconsin School of Medicine and Public Health. MSCs were culture expanded from discarded bone marrow filters after bone marrow harvest from normal healthy sibling HLA-matched donors. We used passages -35 for our experiments. Ex vivo culture expanded MSCs were characterized by their cell surface phenotype (positive for MSC markers: CD29, CD44, CD73, CD90, and CD105; and negative for hematopoietic markers: CD31, CD34, and CD45), and their differentiation potential into bone, fat and cartilage. Monocytes were isolated from peripheral blood mononuclear cell fraction of healthy donors using CD14+ Miltenyi magnetic bead cell separation method. We cultured human CD14+ monocytes for seven days without any added cytokines to generate macrophages, and then co-cultured them for three more days with culture-expanded MSCs. We used cell surface antigen expression and intracellular cytokine expression patterns to study the immunophenotype of macrophages at the end of this co-culture period, and phagocytic assays to investigate their functional activity in vitro. Macrophages co-cultured with MSCs consistently showed high level expression of CD206, a marker of alternatively activated macrophages, in addition to being positive fro CD14 marker. Using CD1a and CD209 staining we did not detect presence of any dendritic cells either at the end of seven days culture of monocyte-derived macrophages or at the end of co-culture period. Furthermore, macrophages that were co-cultured with MSCs expressed high levels of IL-10 and low levels of IL-12, as determined by intracellular staining, typical of alternatively activated macrophages. However, macrophages co-cultured with MSCs also expressed high levels of IL-6 and low levels of TNF-α, compared to controls. Functionally, macrophages co-cultured with MSCs showed a higher level of phagocytic activity using Alexa 488-conjugated E. coli phagocytic assay. In summary we describe a novel type of human macrophage generated in vitro after co-culture with MSCs that assume an immunophenotype defined as IL-10 high, IL-12 low, IL-6 high and TNF-α low secreting cells. These MSC-educated macrophages may be a unique and novel type of alternatively activated macrophages with potentially significant role in tissue repair. Disclosures:No relevant conflicts of interest to declare.

Magnetic Separation of Cells in Coculture Systems Using Magnetite Cationic Liposomes

In tissue engineering, coculture systems have been employed for two major purposes: (1) construction of tissue and organ substitutes (e.g., coculture of parenchymal and nonparenchymal cells in liver tissue engineering) and (2) maintenance of cellular functions (e.g., coculture of embryonic stem cells with embryonic fibroblasts as the feeder cells). For the characterization and recovery of specific cell types, however, target cells have to be isolated from other cells. We report here a novel magnetic separation method to isolate target cells in coculture systems. In this method, target cells were cocultured with nontarget cells labeled with magnetite cationic liposomes (MCLs). Thus, when necessary, the MCL-labeled nontarget cells were magnetically removed from the coculture, resulting in negative isolation of the target cells. As the separation models, three deferent types of coculture systems were examined: rat hepatocytes with various MCL-labeled cells (mouse NIH3T3, STO, or human umbilical vein endothelial cells), human keratinocyte HaCaT cells with MCL-labeled NIH3T3 cells, and mouse embryonic stem cells with MCL-labeled STO cells. In these cocultures, target cells were separated with 94% purity and 98%recovery yield on average. This technique provides a promising approach to isolate and recover target cells for further analysis and application.

Development of magnetic separation system of magnetoliposomes

The magnetic separation technology using sub-microsized ferromagnetic particle is indispensable in many areas of medical biosciences. For example, ferromagnetic particles (200–500 nm) are widely used for cell sorting in stem cell research with the use of cell surface-specific antigens. Nanosized ferromagnetic particles (10–20 nm) have been suggested as more suitable in drug delivery studies given their efficiency of tissue penetration, however, the magnetic separation method for them has not been established. One of the major reasons is that magnetic force acting on the object particles decreases drastically as a particle diameter becomes small. In this study, magnetic force acting on the targets was enhanced by the combination of superconducting magnet and the filter consisting of ferromagnetic particle. By doing so, we confirmed that Fe 3O 4 of 20 nm in diameter was trapped in the magnetic filter under an external magnetic field of 0.5 T. Fe 3O 4 encapsulated with phospholipid liposomes of 200 nm in diameter was also shown to be trapped as external magnetic field of 1.5 T, but not of 0.5 T. We also showed the result of particle trajectory calculation which emulated well the experimental data.

Magnetic nanocomposites based on hypercrosslinked polystyrenes

Magnetic sorbents (composites with inclusions of iron oxide nanoparticles in a polymer matrix), which can be used to remove toxic compounds by the magnetic separation method, have been developed on the basis of hypercrosslinked polystyrenes. Composites based on gel-type hypercrosslinked polystyrenes contain nanoparticles with a radius of ∼3 nm, while biporous hypercrosslinked polystyrenes (with micro- and macropores) contain nanoparticles with a radius of ∼8.5 nm (mainly magnetite). Macropores with a radius of ∼50 nm have been revealed in biporous hypercrosslinked polystyrenes.

Relevance of geological aspects and ore mineralogy in selecting beneficiation methods for processing of eastern Indian iron ores

Geological aspects, particularly mineralogy and ore genesis of different iron ores have important roles to play in understanding their behaviour during processing and decide suitable beneficiation method for particular type of ore so to produce desired quality end products. The implications of different geological aspects and mineralogical characteristics specific to ore types in mineral beneficiation have been outlined in this paper. Experiments indicated that iron ores, such as massive hard ores, laminated hard ores, fine powdery ore and blue dust ore, do not require complicated processing, however at the other end; sub grade ores, such as flaky, friable, shaly, ochrous, powdery, lateritic and goethitic ores having low iron and high alumina content, require specific beneficiation treatments before their use as direct or as agglomerates in the blast furnace feed. While processing, different ore types need treatment differently for their up gradation. Hence, in addition to the conventional methods of processing such as crushing, screening and washing, advanced beneficiation techniques using concepts of gravity and magnetic separation have found their specific applications for beneficiation of different types of ores, based upon their physicochemical and mineralogical characteristics. Geological setup of the deposits and mode of occurrences of different ore types, physical, chemical and mineralogical characterisation and extensive beneficiation experiments conducted on Indian iron ores have established that quality of lumps can substantially be up graded through simple processing and log washing. On the other hand, for fines ores, Jigging has been found to be the best suitable method. Slime beneficiation requires combination of processes and treatment through hydrocyclones, multigravity separation, magnetic separation and sink float methods, etc. These applications would help not only to recover more values from the inferior grades of iron ores but also to conserve and preserve the natural resources too.

Study on magnetic separation system using high Tc superconducting bulk magnets for water purification technique

The application of superconducting bulk magnets to the magnetic separation techniques has been investigated for the Mn-bearing waste water drained from the university laboratories. The research has been conducted in comparison with the electromagnets, and the cryo-cooled superconducting solenoid magnet. The separation ratios of ferrite precipitates including Mn element in the waste slurry were estimated by means of the high gradient magnetic separation method with ferromagnetic iron filters in the water channel and open gradient magnetic separation without them. As the magnetic force acting on the particles is given by the product of a magnetization of particles and a gradient of magnetic field, and a superconducting bulk magnet shows a sharp gradient of the magnetic field on the surface, the performances of the bulk magnet system were almost equivalent to those of the superconducting solenoid magnet with wide bore with respect to the magnetic separation ratios. The separation ratios for Mn have reached over 80 % for HGMS and 10 % for OGMS under the flow rates less than 3 liter/min.

혈액 세포의 고유자성을 이용한 마이크로 자기영동 세포분리기

This paper presents the characterization of a continuous magnetophoretic microseparator for separating white and red blood cells from peripheral whole blood cells based on their native magnetic properties. The magnetophoretic microseparator separated the blood cells using a high gradient magnetic separation (HGMS) method without the use of additives such as magnetic beads or probing materials. Experimental results show that the paramagnetic capture mode microseparator can continuously separate out 93.5% of red blood cells and 97.4% of white blood cells from diluted whole blood, and the diamagnetic capture mode microseparator can continuously separate out 89.7% of red blood cells and 72.7 % of white blood cells by using applying an external magnetic flux of 0.2 T using a permanent magnet.

Preparation, Characterization, and Testing of Magnetic Carriers for Arsenic Removal From Water

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> To remove arsenic from water we are developing a research project that applies magnetic separation methods. In order to increase the removal efficiency we are using magnetic aggregates. These magnetic aggregates are iron-based and were all (except for one) prepared by us. In this paper we report the preparation steps and some of the results of the characterization and absorption tests we have performed in order to conclude about its structure and efficiency in what concerns arsenic removal. </para>

Application of HTS bulk magnet system to the magnetic separation techniques for water purification

We have investigated the application of the HTS bulk magnets to the magnetic separation techniques for the waste water drained from the university laboratories. The study has been conducted in comparison with the electromagnets, and the cryo-cooled superconducting solenoid magnet. A superconducting bulk magnet has the highest value of the trapped magnetic fields at the centre of the sample surface, showing a sharp gradient of the magnetic field on the surface. Magnetic force acting on magnetic particles in magnetic fields is given by the product of a magnetization of particles and a gradient of magnetic field. The HTS bulk is superior to a solenoid magnet which has a poor gradient in magnetic fields in a bore. The separation ratios of ferrite precipitates in the waste slurry were estimated by means of the high gradient magnetic separation method which requires iron filters in the water channel and open gradient magnetic separation without any filters. The magnetic separation using HTS bulk magnet is substantially effective for the practical water purification.

Recent advances in microparticle continuous separation

Recent advances in microparticle separation in continuous flow are presented. It is intended for scientists in the field of separation science in biology, chemistry and microsystems engineering. Recent techniques of micron-sized particle separation within microsystems are described with emphasis on five different categories: optical, magnetic, fluidic-only, electrical and minor separation methods. Examples from the growing literature are explained with insights on separation efficiency and microengineering challenges. Current applications of the techniques are discussed.