Microscopes able to image magnetic fields are an increasingly important tool, not only for material physics but also for industry where they are used to check the magnetic field of hard disk write heads. The NV center in diamond – an atomic-size color defect – is a promising candidate for the next generation of sensor heads for magnetic field microscopes. It can sense magnetic fields with high (nT) sensitivity and, more importantly, sub-nm resolution. This latter property is an order of magnitude better than existing techniques such as magnetic force microscopy.
Imaging of magnetic fields with NV centers has been demonstrated before, but has so far required sophisticated and error-prone control techniques (e.g. lock-in detection). Prof. Wachtrup in Stuttgart and his team now managed to radically simplify this technique with the help of a computer-optimized spectroscopy protocol based on a technique known as optimal control. His protocol switches off fluorescence of a scanning color center whenever the magnetic field reaches one of several magic values. Scanning through a spatially varying magnetic field, fluorescence of the center simultaneously images multiple contour lines of the magnetic field – lines where the field takes on one of the magic values. This pattern is visually and conceptually analogous to tree lines in biology, which – mathematically phrased – reveal all parts of a piece of wood that were grown by the tree at a particular instant in time. Technically, this contour line pattern can be used to quantitatively reconstruct a map of the full magnetic field, just as tree-rings can reveal the growth history of a tree.
The inventors demonstrated their technique by imaging a MFM-tip as an example of a magnetic nanostructure, gaining previously unknown insights into its magnetic field structure. It was then used to check different models of the MFM-tip's magnetic field for validity.
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Enming Zhang, Erik Renström, Martin Koch et al. examined whether the rotational nanoparticle movement could be used for remote induction of cell death by injuring lysosomal membrane structures - without magnetic hyperthermia. They further hypothesized that the shear forces created by the generation of oscillatory torques (incomplete rotation) of SPIONs bound to lysosomal membranes would cause membrane permeabilization, lead to extravasation of lysosomal contents into the cytoplasm, and induce apoptosis. To examine this experimentally, they covalently conjugated SPIONs with antibodies targeting the lysosomal protein marker LAMP1 (LAMP1-SPION).
Remote activation of slow rotation of LAMP1-SPIONs significantly improved the efficacy of cellular internalization of the nanoparticles. Furthermore, the magnetic nanoparticles induced both early and late apoptosis remotely. Dynamic magnetic field generation, which the authors termed DMF, might thus be an important platform technology for novel biomedical applications.
Check the article and details for yourself here.
“Size was key to this experiment,” says Jonathan Schneck, M.D., Ph.D., a professor of pathology, medicine and oncology at the Johns Hopkins University School of Medicine’s Institute for Cell Engineering. “By using small enough particles, we could, for the first time, see a key difference in cancer-fighting cells, and we harnessed that knowledge to enhance the immune attack on cancer.”
Dr. Schneck’s team has pioneered the development of artificial white blood cells, so-called artificial antigen-presenting cells (aAPCs), which show promise in training animals’ immune systems to fight diseases such as cancer. To do that, the aAPCs must interact with naive T cells that are already present in the body, awaiting instructions about which specific invader they will battle. The aAPCs bind to specialized receptors on the T cells’ surfaces and present them with distinctive proteins called antigens. This process activates the T cells, programming them to battle a specific threat such as a virus, bacteria or tumor, as well as to make more T cells.
Strong magnetic fields typically interfere with superconductivity. However, researchers at the Paul Scherrer Institute have discovered a material, CeCoIn5, where a magnetic field creates superconductivity. The superconducting state is in addition to, and simultaneous with, a first superconducting state that appears at low temperatures. Furthermore, an addi-tional antiferromagnetic order was observed, and it was discovered with the SINQ neutron source. This discovery ultimately demonstrates the direct control of quantum states, an im-portant discovery for future quantum computers.
Microchip-based cell sorting is being used in basic and clinical research to isolate a variety of cell types for investigative purposes: stem cells from bone marrow and immune or cancer cells from blood, for example. This same technology technology expands now into cell sorting: Based on cutting-edge microchip technology, the MACSQuant® Tyto ensures high-speed, high-purity, fluorescence-based cell sorting in a fully enclosed, sterile cartridge system. Owl Biomedical Inc developed the chip, and Miltenyi Biotec is now selling it for everyday use.
Advantages of this system are supposedly
- high cell viability, no sheath fluids, no droplet formation
- high-speed valve allowing for the sorting of high numbers of cells in a short period of time
- contamination free enclosed system that also prevents operator from contact with potentially harmful sample materials.
For more information, check out Miltenyi's recent MACS&more Vol 15-2, 2013 magazine.
Rare-earth magnets are indispensable components in computer hard drives, wind turbines, audio speakers, and electric vehicles. Because of the insecure supply chain and price fluctuations of rare-earth metals, scientists are interested in developing efficient, safe, and environmentally friendly methods for recycling magnets to recover the metals.
Tom Vander Hoogerstraete, Koen Binnemans, and coworkers at the University of Leuven, in Belgium, have come up with such a method, one that relies on extracting the metals with an ionic liquid ( Green Chem., DOI: 10.1039/c3gc40198g ). A common way to separate metal ions is by liquid-liquid extraction of acidic aqueous solutions of dissolved metal ions with an organic solvent containing an extraction agent. Rather than using a volatile, flammable solvent as is customary, the Leuven researchers tried ionic liquids, which are nonvolatile, nonflammable organic-based salts with low melting points. By using a tetraalkylphosphonium chloride ionic liquid, which functions as both a solvent and extraction agent, the researchers separated cobalt from samarium and iron from neodymium with better than 99.98% efficiency. They focused on those metal combinations because samariumcobalt and neodymium-iron-boron magnets are two of the most common types of rareearth magnets. After the extractions, the researchers stripped the cobalt and iron out of the ionic liquid so they could reuse it.
NanoScan specializes in the measurement of magnetic properties of materials at the nanoscale, using scanning probe microscopy. The Swiss company aims to achieve the best magnetic lateral resolution in direct space, with minimal time for measurement. To achieve this, its team of physicists, electrical engineers and software engineers develops the
company’s microscopes, from the mechanical parts to the electronics controller and the software, with the desire to provide high-resolution scanning probe microscopes that fulfill present and future analytical needs on nanometer-sized
Dr Raphaëlle Dianoux, NanoScan’s CEO, says: “Our aim was to establish a niche application, and that was magnetic force microscopy. Designed for research, development and quality control of magnetic storage media and other magnetic material, our product, the hr-MFM (high-resolution magnetic force microscope), is an analytical and quantitative magnetic imaging system.” For an imaging example, see the magnetic force microscopy image to the right of a commercial hard disk, taken with the hr-MFM. The single bits are clearly recongnizable as bright (dark) patterns magnetized in the direction opposite (parallel) to the tip magnetization. The high resolution of the microsccope reveals the slightly curved and even grainy substructure of the bits.
Navid Hakimi and others in Dae Kun Hwang's research group at Ryerson University, Toronto, Canada are masters of making strangely shaped three-dimensional anisotropic microparticles using a simple one-step microfluidic based method.
The method exploits the non-uniformity of the polymerizing UV light, UV absorption by opaque nanoparticles in the precursor solution, and discontinuous photomask patterns to make magnetic and non-magnetic microparticles in a two-dimensional microchannel. Numerical simulations of monomer conversion in the microfluidic channel are performed to predict the manufactured particle shape.
For more details, check out the article here: DOI: 10.1002/adma.201304378.
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