As people age, the tiny hairlike cells lining the inner ear can become damaged, leading to hearing loss. A new method that uses magnetic nanoparticles to stimulate these hair cells could help researchers better understand how the cells function and fail (ACS Nano 2014, DOI: 10.1021/nn5020616).
Some 16,000 hair cells line the cochlea in the inner ear, detecting motion produced by sound waves and transmitting electrical signals to nerves in a process that results in hearing. To understand how to protect or repair these cells, researchers must first understand how they work under normal circumstances. And so far, that process has been cumbersome and complicated.
Traditionally, researchers use a glass probe, attached directly to a hair-cell bundle, to physically push the bundle and stimulate the hair cells. Because the probe is so heavy, it adds mass to the delicate hairs in an uncontrolled way that can interfere with the experiment. “That loading could change what you’re measuring,” says Dolores Bozovic of the University of California, Los Angeles.
Bozovic and Jinwoo Cheon of Yonsei University, in Seoul, thought that magnetic nanoparticles could manipulate the hair bundles without adding extra load. They and their colleagues synthesized 50-nm-wide cubic nanoparticles from zinc and iron. They coated the particles with silica to increase their solubility in water and with polyethylene glycol to prevent them from clumping together. Then the researchers attached a protein called concanavalin A to the particles. This protein binds to glycoproteins on the surface of hair cells, which allowed the scientists to attach nanoparticles to hair cells taken from the ear of the North American bullfrog (Rana catesbeiana). By applying an oscillating magnetic field to a plate containing the ear cells, the researchers found that they could push and pull the nanoparticle-laden hairs at frequencies ranging up to 10,000 Hz. They recorded the movements with a high-speed camera and used software to determine the frequencies.
Prof. Makoto Nokata has developed a new type of medical micro robot which can be driven around in the abdominal cavity using a magnetic force. The motion of the robot, move environment and the pictures from an internal camera were investigated in vivo using a simple prototype. The friction force between the abdominal wall and organs was measured, while the prototype model could be guided by simple magnetic field control. This internal micro robot might be a useful medical tool.
There are also a couple of movies about this magnetically directed robot on Prof. Nokata's website.
A chip-scale device that both produces and detects a specialized gas used in biomedical analysis and medical imaging has been built and demonstrated at the National Institute of Standards and Technology (NIST). The new microfluidic chip produces polarized (or magnetized) xenon gas and then detects even the faintest magnetic signals from the gas.
Polarized xenon, with the atoms’ nuclear “spins” aligned like bar magnets in the same direction, can be dissolved in liquids and used to detect the presence of certain molecules. A chemical interaction with target molecules subtly alters the magnetic signal from the xenon; by detecting this change researchers can identify the molecules in a complex mixture. Polarized xenon is also used as a contrast agent to enhance images in experimental magnetic resonance imaging (MRI) of human lungs, but conventional systems for producing and using this gas can be as big as a car.
Researchers from NIST and three other institutions developed the new chip, which might be used to reduce the size and cost of some instruments that, like MRI, rely on nuclear magnetic resonance (NMR). The chip’s sensitive internal detector boosts the response of microfluidic NMR on small samples and eliminates the need for the powerful magnets associated with larger NMR devices such as those used in MRI. The microfabricated chip could be mass produced and integrated easily with existing microfluidic systems.
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A new network grant has recently been approved in Europe, the TDCOST Action TD 1402: Multifunctional Nanoparticles for Magnetic Hyperthermia and Indirect Radiation Therapy (RADIOMAG)
The Action aims to bring together and to organise the research outcomes from the different participating network members in a practical way to provide clinicians with the necessary input to trial a novel anti-cancer treatment combining magnetic hyperthermia and radiotherapy, also identifying future research objectives upon appraisal of the obtained results. Feedback between the different working groups here is essential, and is expected that the lifetime of this Action proposal will eventually result in a compendium of best practices for magnetic hyperthermia.
RADIOMAG will generate new and strengthen the existing synergies between technical advances (thermal imaging / MH), new treatment concepts (combined targeting radiosensitisation and magnetic thermotherapy) and biocompatible coating in order to achieve a breakthrough in the clinical application of magnetic hyperthermia. Due to the complexity of this aim, synergies can only be achieved on a longer time frame, by means of workshops, STSMs, joint publications, common Horizon 2020 research proposals and exchange with other COST Actions (e.g. TD1004, TD1205).
The company Nanocomposix published a very good introduction into particle size measurement with dynamic light scattering (DLS) measurement. After analyzing thousands of nanoparticle samples they have assembled a set of guidelines that can be used to determine how to maximize the quality of your DLS data and, more importantly, how to interpret your results. Check it out here. And if you have more questions, contact them at firstname.lastname@example.org or (858) 565-4227 x 2.
The smallest robot worldwide is only a few micrometer long and has been created at ETH Zurich. The robot designed to be steered through the human body forces high design chal-lenges on the researchers in terms of control and power supply. It is inspired by the flagella of the E. coli bacteria, which allows highly efficient locomotion. The metallic replica of the flagella is set in rotation by an external magnetic field, whose direction and intensity can be regulated and adjusted according to the direction the robot should swim. The ETH spin-off Aeon Scientific is currently working on the marketing of the new control technology.
The toxicity of many drugs creates high risk of destroying healthy cells when attempting to treat disease. Scientists at ETH Zurich’s Institute of Robotics and Intelligent Systems (IRIS) have developed a tiny robot about a half-millimeter in diameter that may provide a solution. The robot comprises a star-shaped, bi-layer, soft hydrogel shell that, when closed, forms a sphere and holds tiny magnetic beads inside. When the robot reaches the desired loca-tion, laser irradiation causes the hydrogel to change shape and the capsule to open, delivering the drug. The hy-drogel robot has been tested only in-vitro, but the scientists believe they can miniaturize it enough to test it in ani-mals in the future.
In nature, magnetosomes—membrane-bound magnetic nanocrystals with unprecedented magnetic properties—can be biomineralized by magnetotactic bacteria, e.g., Magnetospirillum gryphiswaldense . However, these microbes are difficult to handle. Isabel Kolinko, Youming Zhang, Dirk Schüler et al. now were able to transfer a minimum set of genes for the biosynthetic pathway of biomineralization of magnetic nanoparticles from these fastidious microorganisms to Rhodospirillum rubrum, a gram negative proteobacterium. Biomineralization of highly ordered magnetic nanostructures was then possible and might in the future allow for the sustainable production of tailored magnetic nanostructures in biotechnologically relevant hosts. This represents a step towards the endogenous magnetization of various organisms by synthetic biology.
Check out the details in this interesting Nature Nanotechnology 9, 193-197 (2014) paper. It includes an editorial.
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