Glioblastoma cells cultured in 3D with the Bio-Assembler. Credit: Nano3D Biosciences

Being able to grow more realistic liver, heart, and other tissues in the lab could provide a new lease on life for patients waiting on the transplant list--and lead to more realistic systems for testing drugs. But tissue engineers have found that mimicking these complex, three-dimensional structures in the lab is difficult. Part of what's holding them up are flat, two-dimensional tissue culture systems that grow cells in an environment very different from that inside the body.

Now researchers at Rice University and the MD Anderson Cancer Center in Houston have developed a simple way to make cells form 3-D structures. They developed a gel made up of a polymer, iron oxide nanoparticles, and engineered viruses called phage. When cells are added to this mixture, the phage cause them to absorb the magnetic particles. The Houston group showed that they could use a weak magnet to hold magnetized brain cancer cells in a 3-D suspension. Gene-expression studies showed that these suspended cells behave more naturally than a control group grown on a conventional flat surface: the cancer cells were producing a mix of proteins very similar to what they produce in the body. These results are described in Nature Nanotechnology this week.

The magnetizing gel has been licensed to a startup company, Nano3D Bioscience, which will run tests to compare the technology other methods for making 3-D tissues.

According to a story posted yesterday on the EE Times Asia website, researchers at Intel are developing materials for use in ultracapacitors, energy storage devices with a high capacity. I contacted the company to find out more, and they say they're not ready to say any more than was in the EE Times story:

Intel Corp. researchers are looking into nanoscale materials that could be used to create ultracapacitors with a greater energy density than today's Li-ion batteries. If successful, the new materials could be mass produced in volumes to power systems ranging from mobile devices to electric vehicles--even smart grid storage units.

The project is one of a handful in the works at a seven-person energy systems research lab formed by Intel Corp. in May. The lab is focused on so-called microgrids, small local electric grids that lab director Tomm Aldridge and others believe could represent the future of the smart electric grid.

Until they're ready to say more, here are some stories on the TR site about similar projects. The story "Nanocapacitors with Big Energy Storage" goes into some of the current limitations of these devices and how nanopore electrodes might address them; "Ultracapacitor Start-Up Gets a Big Boost" looks at an ARPA-E funded MIT spin-out that's making ultracapacitors from arrays of carbon nanotubes.

This device uses magnetic fields to separate cells by size and shape. Credit: Hur Koser

Researchers at Yale have demonstrated a device that uses a magnetic liquid to separate blood cells based on their size and shape in just minutes.

The device applies a magnetic field to a liquid containing magnetic nanoparticles. The nanoparticles create waves that carry cells along depending on their size, shape and mechanical properties. The researchers, led by electrical engineering professor Hur Koser, hope to develop a cheap alternative to cell-sorting techniques that are time-consuming and sometimes require expensive labeling.

Liquid suspensions of magnetic particles, called ferrofluids, are already used as industrial lubricants and in loudspeakers and computer hard disks. These liquids typically contain other chemicals to keep the particles from clumping together and from coming out of the suspension. Magnetic nanoparticles are also being explored for cancer therapies and as contrast agents for magnetic resonance imaging (MRI)--both applications that require very low concentrations.

But the Yale group is the first to make a high-concentration, biocompatible ferrofluid that doesn't contain any chemicals that are harmful to cells, yet still keeps the particles afloat. "It was very tricky to find the parameters to maintain live cells," says Koser.

In experiments described this week in the Proceedings of the National Academy of Sciences, the Yale researchers made microfluidic channels lined with magnetic-field-generating electrodes. Cells were then added to a ferrofluid in the channel. When magnetic fields were applied along the device, the particles in the fluid pushed the cells along the channel, separating them by size and shape. Something similar can be accomplished using electrical fields, says Koser, but this can damage the cells. His group used the device to separate live blood cells from sickle cells and bacteria.

Koser believes the device could be especially helpful when trying to detect very rare types of blood cell, such as cancerous ones. Rapidly sorting cells using magnetic fields could improve the sensitivity of tests for these rare cells without adding any costly chemical labels. Tumor cells are squishier than healthy ones--possibly because they grow quickly and so don't form a proper internal cell skeleton--and Koser hopes that magnetic fields will also be able to separate cells based on their elasticity and other mechanical properties.

"The next step is to try this in conjunction with existing sensors to improve their sensitivity and cut down on time," says Koser.

In the video below, a magnetic field creates waves in a liquid containing magnetic nanoparticles (the nanoparticles are not visible) to separate two types of microbeads based on their size.