Researchers from MIT and Harvard have developed a new design for a nanotube-based device that can trap circulating tumor cells (CTC’s), and potentially viruses. The device is an upgrade of an earlier prototype, which performed fairly well but let too many CTC’s pass through without detection.
Toner [Mehmet Toner, professor of biomedical engineering at Harvard Medical School and a member of the Harvard-MIT Division of Health Sciences and Technology] built an earlier version of the device four years ago. In that original version, blood taken from a patient flows past tens of thousands of tiny silicon posts coated with antibodies that stick to tumor cells. Any cancer cells that touch the posts become trapped. However, some cells might never encounter the posts at all.
Toner thought if the posts were porous instead of solid, cells could flow right through them, making it more likely they would stick. To achieve that, he enlisted the help of Brian Wardle, an MIT associate professor of aeronautics and astronautics, and an expert in designing nano-engineered advanced composite materials to make stronger aircraft parts.
Out of that collaboration came the new microfluidic device, studded with carbon nanotubes, that collects cancer cells eight times better than the original version.
When designing advanced materials, Wardle often uses carbon nanotubes — tiny, hollow cylinders whose walls are lattices of carbon atoms. Assemblies of the tubes are highly porous: A forest of carbon nanotubes, which contains 10 billion to 100 billion carbon nanotubes per square centimeter, is less than 1 percent carbon and 99 percent air. This leaves plenty of space for fluid to flow through.
The MIT/Harvard team placed various geometries of carbon nanotube forest into the microfluidic device. As in the original device, the surface of each tube can be decorated with antibodies specific to cancer cells. However, because the fluid can go through the forest geometries as well as around them, there is much greater opportunity for the target cells or particles to get caught.
The researchers can customize the device by attaching different antibodies to the nanotubes’ surfaces. Changing the spacing between the nanotube geometric features also allows them to capture different sized objects — from tumor cells, about a micron in diameter, down to viruses, which are only 40 nm.
Link @ MIT: Catching cancer with carbon nanotubes…
Abstract in journal Small: Nanoporous Elements in Microfluidics for Multiscale Manipulation of Bioparticles
Flashback: Microchips for Tumor Detection