磁分离仪分离磁性细菌的新方法

磁性细菌胞内可以产生磁性颗粒,因此具有趋磁性,基于这种特性,利用磁分离的原理,本研究开发了一种磁性细菌分离仪,提供了一种分离磁性细菌的新方法。以氧化亚铁硫杆菌为例,使用磁性细菌分离仪进行分离,可以得到强磁菌和弱磁菌。利用透射电镜观察,强磁菌胞内磁性颗粒明显多于弱磁菌;半固体平板磁泳实验也表明强磁菌趋磁性明显强于弱磁菌。各项实验结果表明磁性细菌分离仪可以有效地分离磁性细菌,这是一种分离磁性细菌的新方法,将促进磁性细菌分离培养的研究。     

An on-chip magnetic bead separator using spiral electromagnets with semi-encapsulated permalloy.

A new planar bio-magnetic bead separator on a glass chip has been designed, fabricated and tested. The separator is composed of micromachined semi-encapsulated spiral electromagnets and fluid channels, which have been separately fabricated and then bonded. The device was tested with super-paramagnetic beads of mean diameter 1 microm which were suspended in a buffered solution. When a DC current of 300 mA was applied to the inductor, the bio-magnetic beads were successfully separated on the electromagnets, showing a functional capability as a magnetic bead separator. To evaluate separation rate and capability, the inductance measurement method has been introduced and the inductance variation according to the separation rate has been characterized. Using this separator, cells or cell fragments and magnetic beads bonded with protein or enzyme suspended in bio-buffer solutions can be successfully separated from their suspensions, envisaging a filterless bio-separator.     

Large-scale separation of magnetic bioaffinity adsorbents

Flat magnetic separator was used to separate magnetic bioaffinity adsorbents from litre volumes of suspensions. Both magnetic cross-linked erythrocytes and magnetic chitosan were efficiently separated; at least 95% adsorbent recovery was achieved at maximum flow rate (1680 ml min^–1). Using this system low amounts of trypsin were concentrated from large sample volumes using magnetic erythrocytes as affinity adsorbent.     

Separation of magnetic affinity biopolymer adsorbents in a Davis tube magnetic separator

A Davis tube (a matrix-free, flow-through magnetic separator used mainly in mineral processing) has been tested for separation of magnetic affinity biopolymer adsorbents from larger volumes of suspensions. Both magnetic chitosan and magnetic cross-linked erythrocytes could be efficiently separated from litre volumes of suspensions. Up to 90% adsorbent recovery was achieved under optimised separation conditions.     

Study of charged particle motion in fields of different configurations for developing the concept of plasma separation of spent nuclear fuel

The concept of plasma separation of spent nuclear fuel in a plane perpendicular to the magnetic field in an electric potential of special configuration is developed. A specific feature of the proposed approach consists in using an accelerating potential for reducing energy and angular spread of plasma ions at the entrance to the separator chamber and a potential well for the spatial separation of ions with different masses. The trajectories of ions of the substance imitating spent nuclear fuel are calculated. The calculations are performed for azimuthal and axial magnetic fields and model electric field configurations corresponding to different geometries of the separator chamber. It is shown that, using magnetic fields with a characteristic strength of 1 kG and electric potentials of up to 1 kV inside a region with a linear size less than 100 cm, it is possible to separate ions of spent nuclear fuel with energies from 0.2 to 3 eV. The calculations were performed for a collisionless mode in the single-particle approximation. Possible variants of the experimental facility for plasma separation of spent nuclear fuel are proposed.     

Casein hydrolysis in stirred tank reactors using chymotrypsin immobilized on magnetic supports

Nickel-NiO-BSA-chymotrypsin has been used to hydrolyze casein in both batch and continuous stirred tank reactors. The kinetics of hydrolysis in both types of reactor were considered. Some operational problems encountered using fine powder catalysts in batch stirred tank reactors are discussed. High gradient magnetic separation was found to be a powerful catalysts retention method for magnetic support particles, particularly when using a ferromagnetic collection matrix. Nickel particles of diameter 3–7 μm were easily separated from water at a processing velocity of 39 mm/sec. Nickel powder and precipitated Fe₃O₄ were also separated satisfactorily using a rotating drum magnetic separator.     

Magnetic bead purification of M13 DNA sequencing templates.

A method for the preparation of multiple M13 DNA sequencing templates is described. No phenol extraction is required and the procedure can be carried out in Eppendorf tubes or 96-well microtiter plates. Starting with a phage supernatant, the entire procedure is carried out in the same reaction vessel and all separation steps are based on a novel application of magnetic bead separation. The design of a 96-well magnetic separator is presented and the application of the method for large-scale sequencing is discussed.     

Cell clarification and size separation using continuous countercurrent magnetophoresis

Nonmagnetic microparticles (e.g., cells, polymer beads) immersed in a magnetic fluid (ferrofluid) under a nonuniform magnetic field experience a magnetophoretic force in the direction of decreasing magnetic field strength. This phenomenon was exploited in the development of a continuous magnetophoretic countercurrent separation for the removal and concentration of micron-sized particles from aqueous suspensions, and in particular as a viable approach for cell clarification of raw fermentation broth. A magnetic fluid is added to the cell suspension, the mixture is introduced to the magnetic separator, which consists of an open flow tube passing between pairs of magnets that move in a direction counter to the flow of the suspension. The cells are pushed ahead of the magnet pairs owing to the magnetophoretic forces acting on them, collected in a tube upstream of the feed injection point, and removed as a concentrated suspension for further treatment.     

Demonstration of a strategy for product purification by high-gradient magnetic fishing: recovery of superoxide dismutase from unconditioned whey

A systematic approach for the design of a bioproduct recovery process employing magnetic supports and the technique of high-gradient magnetic fishing (HGMF) is described. The approach is illustrated for the separation of superoxide dismutase (SOD), an antioxidant protein present in low concentrations (ca. 0.15-0.6 mg L(-1)) in whey. The first part of the process design consisted of ligand screening in which metal chelate supports charged with copper(II) ions were found to be the most suitable. The second stage involved systematic and sequential optimization of conditions for the following steps: product adsorption, support washing, and product elution. Next, the capacity of a novel high-gradient magnetic separator (designed for biotechnological applications) for trapping and holding magnetic supports was determined. Finally, all of the above elements were assembled to deliver a HGMF process for the isolation of SOD from crude sweet whey, which consisted of (i) binding SOD using Cu2+ -charged magnetic metal chelator particles in a batch reactor with whey; (ii) recovery of the "SOD-loaded" supports by high-gradient magnetic separation (HGMS); (iii) washing out loosely bound and entrained proteins and solids; (iv) elution of the target protein; and (v) recovery of the eluted supports from the HGMF rig. Efficient recovery of SOD was demonstrated at approximately 50-fold increased scale (cf magnetic rack studies) in three separate HGMF experiments, and in the best of these (run 3) an SOD yield of >85% and purification factor of approximately 21 were obtained.     

An Upgraded Lithium Ion Battery Based on a Polymeric Separator Incorporated with Anode Active Materials

Structural/compositional characteristics at the anode/electrolyte interface are of paramount importance for the practical performance of lithium ion batteries, including cyclic stability, rate capacity, and operational safety. The anode‐electrolyte interface with traditional separator technology is featured with inevitable phase discontinuity and fails to support the stable operation of lithium ion batteries based on large‐capacity anodes with structural change in charges/discharges, such as transition metal oxide anodes. In this work, an anode/electrolyte framework based on an oxide anode and an active‐oxide‐incorporated separator is proposed for the first time and investigated for lithium ion batteries. The architecture builds a robust anode‐separator interface in LIBs, shortens Li⁺ diffusion path, accelerates electron transport, and mitigates the volume change of the oxide anode in electrochemical reactions. Remarkably, 4 wt% CuO addition in the separator leads to a 17% enhancement in the overall capacity of a battery with a CuO anode. The battery delivers an unparalleled record reversible capacity of 637.2 mAh g^?1 with a 99% capacity retention after 100 charge/discharge cycles at 0.5 C. The high performance are attributed to the robust anode‐separator interface, which gives rise to enhanced interaction between the oxide anode and the same‐oxide‐incorporated composite in the separator.     

A magnetic adsorbent-based process for semi-continuous PEGylation of proteins

A semi-continuous magnetic particle-based process for the controlled attachment of PEG (PEGylation) to proteins is described for the first time. Trypsin and 2 kDa mono-activated PEG were used to systematically develop the steps in the process. Proof of concept was shown in a microfluidics system to minimize reagent consumption. Two streams containing (i) 1.2 g/L trypsin and (ii) 4 g/L magnetic adsorbents derivatized with the reversible affinity ligand benzamidine were pumped into a pipe reactor. At the exit, a third solution of activated PEG (0-40 g/L) was introduced and the solutions immediately fed into a second reactor. Upon exiting, the mixture was combined in a third reactor with a fourth stream of free amine groups to stop the reaction (50 mM lysine). The mixture continued into a high-gradient magnetic separator where magnetic supports, with PEGylated trypsin still attached, were captured and washing and elution steps were subsequently carried out. Analysis of the conjugates (with SDS-PAGE & LC-MS) showed that the extent of PEGylation could be controlled by varying the reaction time or PEG concentration. Furthermore, the PEG-conjugates had higher enzyme activity compared to PEGylation of non-immobilized trypsin.     

Scalable air cathode microbial fuel cells using glass fiber separators, plastic mesh supporters, and graphite fiber brush anodes

The combined use of brush anodes and glass fiber (GF1) separators, and plastic mesh supporters were used here for the first time to create a scalable microbial fuel cell architecture. Separators prevented short circuiting of closely-spaced electrodes, and cathode supporters were used to avoid water gaps between the separator and cathode that can reduce power production. The maximum power density with a separator and supporter and a single cathode was 75 ± 1 W/m³. Removing the separator decreased power by 8%. Adding a second cathode increased power to 154 ± 1 W/m³. Current was increased by connecting two MFCs connected in parallel. These results show that brush anodes, combined with a glass fiber separator and a plastic mesh supporter, produce a useful MFC architecture that is inherently scalable due to good insulation between the electrodes and a compact architecture.     

First comprehensive view on a magnetic separation based protein purification processes: From process development to cleaning validation of a GMP‐ready magnetic separator

Magnetic separation processes are known as integrated bioanalytical protein purification method since decades and are well described. However, use of magnetic separation processes in a regulated industrial production environment has been prevented by the lack of suitable process equipment and prejudice against the productivity of the process and its qualification for cleaning‐in‐place operation. With the aim of overcoming this prejudice, a comprehensive process development approach is presented, based on a GMP‐compliant magnetic separator, including an optimization of the batch adsorption process, implementation into a technical‐scale, and the development and validation of cleaning routines for the device. By the implementation of a two‐step counter‐current binding process, it was possible to raise the yields of the magnetic separation process even for very low concentrated targets in a vast surplus of competing proteins, like the hormone equine chorionic gonadotropin in serum, from 74% to over 95%. For the validation of the cleaning process, a direct surface swabbing method combined with a total organic carbon analysis was established for the determination of two model contaminants. The cleanability of the process equipment was proven for both model contaminants by reliably meeting the 10 ppm criteria.     

Multifunctional Manganese Ions Trapping and Hydrofluoric Acid Scavenging Separator for Lithium Ion Batteries Based on Poly(ethylene‐alternate‐maleic acid) Dilithium Salt

Manganese dissolution from positive electrodes seriously reduces the life of Li‐ion batteries, due to its detrimental impact on the passivation of negative electrodes. A novel multifunctional separator incorporating inexpensive mass‐produced polymeric materials may dramatically increases the durability of Li‐ion batteries. The separator is made by embedding the poly(ethylene‐alternate‐maleic acid) dilithium salt polymer into a poly(vinylidene fluoride‐hexafluoropropylene) copolymer matrix. LiMn₂O₄‐graphite cells comprising a 1 m LiPF₆ solution in ethylene carbonate plus dimethyl carbonate (1:1 v/v) and the functional separator retain 31% and 100% more capacity than baseline cells with plain commercial separators after 100 cycles at C/5 rate, respectively, at 30 and 55 °C. Analyses of cycled cells indicate greatly reduced Mn contamination of the graphite negative electrodes and almost no irreversible structural change in the LiMn₂O₄ positive electrodes from cells containing the functional separator. The Mn amount in the graphite electrodes from cycled cells with functional separators is ≈80% lower than in the graphite electrodes from cycled baseline cells. Mn ions are found in the functional separators but not in baseline (plain) separators from cycled cells. Finally, it is shown that the reported performance improvements stem from the ability of the novel separator to chelate Mn ions and to scavenge trace HF.     

Cobalt separation by <Emphasis Type="Italic">Alphaproteobacterium</Emphasis> MTB-KTN90: magnetotactic bacteria in bioremediation

Bioremediation of toxic metals by magnetotactic bacteria and magnetic separation of metal-loaded magnetotactic bacteria are of great interest. This bioprocess technique is rapid, efficient, economical, and environmentally friendly. In this study, cobalt removal potential of a novel isolated magnetotactic bacterium (Alphaproteobacterium MTB-KTN90) as a new biosorbent was investigated. The effects of various environmental parameters in the cobalt removal and the technique of magnetic separation of cobalt-loaded bacterial cells were studied. Cobalt removal by MTB-KTN90 was very sensitive to pH solution; higher biosorption capacity was observed around pH 6.5–7.0. When biomass concentration increased from 0.009 to 0.09 g/l, the biosorption efficiency increased from 13.87 % to 19.22 %. The sorption of cobalt by MTB-KTN90 was rapid during the first 15 min (859.17 mg/g dry weight). With the increasing of cobalt concentrations from 1 to 225 mg/l, the specific cobalt uptake increased. Maximum cobalt removal (1160.51 ± 15.42 mg/g dry weight) took place at optimum conditions; pH 7.0 with initial cobalt concentration of 115 mg/l at 60 min by 0.015 g/l of dry biomass. The results showed maximum values for constants of Langmuir and Freundlich models so far. The biosorption mechanisms were studied with FTIR, PIXE, and FESEM analysis. Cobalt-loaded MTB-KTN90 had ability to separate from solution by a simple magnetic separator. Magnetic response in MTB-KTN90 is due to the presence of unique intracellular magnetic nanoparticles (magnetosomes). The orientation magnetic separation results indicated that 88.55 % of cobalt was removed from solution. Consequently, Alphaproteobacterium MTB-KTN90 as a new biosorbent opens up good opportunities for the magnetic removal of cobalt from the polluted aquatic environments.     

Highly Stable Lithium–Sulfur Batteries Based on Laponite Nanosheet‐Coated Celgard Separators

Lithium–sulfur (Li–S) batteries are of great interest due to their high theoretical energy density. However, one of the key issues hindering their real world applications is polysulfide shuttle, which results in severe capacity decay and self‐discharge. Here, a laponite nanosheets/carbon black coated Celgard (LNS/CB‐Celgard) separator to inhibit polysulfide shuttle and to enhance the Li⁺ conductivity simultaneously is reported. The polysulfide shuttle is efficiently inhibited through strong interactions between the O active sites of the LNS and polysulfides by forming the Li···O and O? S bonds. Moreover, the separator features high Li⁺ conductivity, fast Li⁺ diffusion, excellent electrolyte wettability, and high thermal stability. Consequently, the Li–S batteries with the LNS/CB‐Celgard separator and the pure S cathode show a high initial reversible capacity of 1387 mA h g^?1 at 0.1 C, high rate performance, superior cycling stability (with a capacity decay rate of 0.06% cycle^?1 at 0.2 C and 0.028% cycle^?1 at 1.0 C over 500 cycles), and ultralow self‐discharge. The separator could also enhance the performance of other batteries such as the LiFePO₄/separator/Li battery. This work sheds a new light on the design and preparation of novel separators for highly stable Li–S batteries via a “green” and cost‐effective approach.     

Highly Stretchable Separator Membrane for Deformable Energy‐Storage Devices

With the emergence of stretchable electronic devices, there is growing interest in the development of deformable power accessories that can power them. To date, various approaches have been reported for replacing rigid components of typical batteries with elastic materials. Little attention, however, has been paid to stretchable separator membranes that can not only prevent internal short circuit but also provide an ionic conducting pathway between electrodes under extreme physical deformation. Herein, a poly(styrene‐b‐butadiene‐b‐styrene) (SBS) block copolymer–based stretchable separator membrane is fabricated by the nonsolvent‐induced phase separation (NIPS). The diversity of mechanical properties and porous structures can be obtained by using different polymer concentrations and tuning the affinity among major components of NIPS. The stretchable separator membrane exhibits a high stretchability of around 270% strain and porous structure having porosity of 61%. Thus, its potential application as a stretchable separator membrane for deformable energy devices is demonstrated by applying to organic/aqueous electrolyte–based rechargeable lithium‐ion batteries. As a result, these batteries manifest good cycle life and stable capacity retention even under a stretching condition of 100%, without compromising the battery's performance.     

Tailoring the Pore Size of a Polypropylene Separator with a Polymer Having Intrinsic Nanoporosity for Suppressing the Polysulfide Shuttle in Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are being considered as one of the most promising candidates for the development of next‐generation energy storage technologies. Although much progress has been made over the past decade, the development of Li–S batteries is still held back by a crucial polysulfide‐shuttle problem. To address this critical issue, an approach to reduce the pore size of the separator is presented here, to prevent the penetration of soluble polysulfide species. A polymer with intrinsic nanoporosity (PIN) is developed within the micrometer‐scale pores of a polypropylene separator. The framework of polypropylene acts as a skeleton to sustain reliable mechanical properties with the thin membrane. Upon the formation of PIN in the pores, the polypropylene separator maintains its thickness. With the thin PIN–polypropylene membrane, the Li–S cells can be operated with a relatively high sulfur loading. The PIN allows the transport of Li⁺ ions, but suppresses the penetration of the polysulfide species. The Li–S batteries with the PIN‐modified polypropylene separator exhibit enhanced cycling performance.     

Integrated Configuration Design for Ultrafast Rechargeable Dual‐Ion Battery

In this work, an integrated dual‐ion battery design is reported with active materials, current collectors, and separator, assembled in one flexible component. An aluminum film is deposited directly onto one side of the 3D porous glass fiber separator to form a porous anode. Cathode active materials are loaded on the other side of the separator with aluminum film deposited on the top as current collector. This design demonstrates ultrafast charge/discharge rate up to 120 C while maintaining high capacity of 116.1 mA h g^?1. Moreover, long‐term stability of over 1500 cycles at a high rate of 60 C is achieved. The estimated energy density remains as high as 232.6 W h kg^?1 at an ultrahigh power density of 22634.5 W kg^?1.     

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

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