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New Nanoparticle-Based Assay Provides Extremely Sensitive Test of Blood Clotting in Mice

October 10, 2014

Tests that look for biomarkers could help physicians diagnose disease before symptoms present themselves. But it’s difficult to find the right protein, metabolite, or other molecule in the body that signals the start of a disease. Now researchers have described a sensitive new assay that generates its own synthetic biomarkers to detect harmful blood clots in mice (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja505676h).

Unfortunately, natural biomarkers that are both specific to a disease and easy to detect are relatively rare. So Sangeeta N. Bhatia of Massachusetts Institute of Technology and David R. Walt of Tufts University decided to develop an assay that caused diseased cells or tissues to produce a synthetic molecule the scientists could easily find.

To create the assay, the scientists combined technologies their two groups had been working on: Bhatia’s group had synthesized worm-shaped iron oxide nanoparticles that they decorated with molecules to home in on diseased cells, while Walt’s team had developed single-molecule arrays (SiMoA) that allowed them to detect extremely low quantities of biological compounds of interest. For the new assay, the two teams decorated the nanoworms with a peptide that can be cleaved by thrombin, an enzyme activated at high levels in clotting disorders. When the nanoparticles bump into active thrombin in a mouse with clotting problems, the enzymes clip off a labeled peptide that the mice then excrete in their urine.

Magnetic Fields Control Liquid Crystals' Optical Properties

October 03, 2014

A new technique that forms and controls magnetically responsive liquid crystals could be applied to many types of displays. Conventional liquid crystals, often used in electronic displays, are composed of tiny rod-like molecules. Researchers at the University of California, Riverside, have created crystal nanorods that rotate and realign themselves parallel to nearby magnetic fields.

“We utilized our expertise in colloidal nanostructure synthesis to produce magnetite nanorods that can form liquid crystals and respond strongly to even very weak magnetic fields,” said lead researchers Dr. Yadong Yin, an associate professor of chemistry at the university. “Even a fridge magnet can operate our liquid crystals.”

The nanorods can also form patterns to control the transmittance of polarized light in selected areas. “Such a thin film does not display visual information under normal light, but shows high contrast patterns under polarized light,” Yin said, noting that this is not possible with commercial liquid crystals.

The new liquid crystals could be used in applications such as signs and displays, optical modulation and anti-counterfeiting efforts, the researchers said. The research was published in Nano Letters (doi: 10.1021/nl501302s).

Stem Cell Therapy of the Aging Brain: Watch With Magnetic Nanoparticles

September 27, 2014

The increase in clinical trials assessing the efficacy of cell therapy for structural and functional regeneration of the nervous system in diseases related to the aging brain is well known. However, the results are inconclusive as to the best cell type to be used or the best methodology for the homing of these stem cells. Alvarim et al wrote a systematic review that analyzes published data on SPION (superparamagnetic iron oxide nanoparticle)-labeled stem cells as a therapy for brain diseases, such as ischemic stroke, Parkinson’s disease, amyotrophic lateral sclerosis, and dementia. Their review highlights the therapeutic role of stem cells in reversing the aging process and the pathophysiology of brain aging, as well as emphasizes nanotechnology as an important tool to monitor stem cell migration in affected regions of the brain.

Check it out here.

Magnetics Technology International Annual Issue 2014

September 13, 2014

Every year, Magnetics Technology International publishes an annual issue. This journal, which describes itself as "The world's leading global review dedicated to advanced magnetics and magnet technologies" is quite interesting. This year, it for example contains stories about magnetic stimulation of the brain, cerium in high energy magnets, precision magnetic field mapping, the synthesis of FePt nanoparticles for use in high-density data storage, and magnetic nanopeapod composites. Amongst many more good articles!

Check it out at http://viewer.zmags.com/publication/2235d3a9#/2235d3a9/3.

There also seem to be few older issues online, for example 2013, 2012, 2011.

Heated Nanoparticles Throw Gene Therapy Switch

September 12, 2014

In a strategy known as gene therapy, scientists insert engineered DNA into diseased cells in order to treat or kill them. Now, researchers have combined nanotechnology and synthetic biology to create a simple switch to turn on such genes inside cells. They demonstrate that heat generated by magnetic nanoparticles activates the engineered genes, slowing tumor growth in mice (ACS Synth. Biol. 2013, DOI: 10.1021/sb4000838).

For gene therapy to reach clinical applications, such as for treating cancer, researchers need to activate their engineered gene sequences only in the diseased cells. That’s because in the course of introducing the synthetic genes, some healthy cells also may pick up the DNA packages. So to prevent activating synthetic genes in healthy cells, researchers want to design genetic circuits that can be triggered selectively.

Currently, there are only a few ways to do that, typically through applying drugs to the cells. Masamichi Kamihira of Kyushu University, in Japan, and his colleagues thought magnetic fields would be a more useful trigger. The fields travel deep into tissues and can be targeted to certain areas of tissue to avoid turning on genes in healthy cells.

Magnetite nanoparticles surrounded by a cationic liposome (see above, left) generate heat when an alternating magnetic field is applied. Inside a cancer cell, the heat (thick red arrow) activates a promoter region (pink, P) in an engineered gene sequence containing instructions for a cell-killing protein (blue, TNF-α). The heat promoter also turns on a gene for a protein called tTA (orange) that activates a second response element (green, TRE) to continually express TNF-α. A sequence in-between (purple, IRES) ensures that both genes get translated into proteins.

Biocomputing Based on Particle Disassembly

September 10, 2014

Maxim and Petr Nikitin and colleagues just published a beautiful paper in the September issue of Nature Nanotechnology. They were even chosen for the cover picture. Check their paper out here.

They explored the computing potential of particle-based systems. They were able to show that almost any type of nanoparticle or microparticle can be transformed into autonomous biocomputing structures that are capable of implementing a functionally complete set of Boolean logic gates (YES, NOT, AND and OR) and binding to a target as result of a computation. The logic-gating functionality was incorporated into self-assembled particle/biomolecule interfaces (demonstrated in their work with proteins) and the logic gating was achieved through input-induced disassembly of the structures. To illustrate the capabilities of the approach, they showed that the structures can be used for logic-gated cell targeting and advanced immunoassays.

Maxim and Petr used magnetic nanoparticles with a diameter of about 100 nm for their work, and detected the particles with their own non-linear magnetization method (MPQ).

The proposed platform can be applied to the development of autonomous nanodevices as intelligent biosensors with built-in biochemical data analysis for multiplex point-of care diagnostics, field testing and so on. Furthermore, with the progress in metabolomics for the identification of new small molecule biomarkers, the platform could be used to construct bionanorobotic agents for complex stimuli-controlled targeted drug delivery, early diagnostics and health monitoring as a part of preventive medicine solutions.

A Blog About Biomagnetic Separation Full of Free Resources

August 30, 2014

SEPMAG who develops, manufactures and markets advanced biomagnetic separation equipment has a very useful website. Their blog contains a wide collection of technical articles and covers all aspects of biomagnetic separation and related topics.

SEPMAG also offers an interesting collection of free ebooks and guides that provide in-depth insights into the most common applications of biomagnetic separation. The two most recent guides are The Advanced Guide to Biomagnetic Protein Purification and The Advanced Guide for the Use of Magnetic Beads in Chemiluminescent Immunoassays. Other guides will help to scale up or validate biomagnetic separation processes, or introduce newcomers to the area. These guides are totally free and can be downloaded by simply filling in a form with your name and email.

Nanomagnets Could Aid Study Of Hearing

July 25, 2014

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.

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Last Modified: December 09, 2013 - Magneticmicrosphere.com 2013