Blood-Testing Device Captures Cancer Cells

A newer version of a device can detect single cancer cells in a blood sample, potentially allowing doctors to determine quickly whether a tumor is metastasizing.

The microfluidic device is studded with carbon nanotubes, which are tiny, hollow cylinders whose walls are lattices of carbon atoms that collect cancer cells eight times better than the original version.

Scientists at the Massachusetts General Hospital, (Charlestown, MA, USA), collaborating with engineers at the Massachusetts Institute of Technology, Cambridge, MA, USA), have refined the cell capturing device. They developed the use of micropatterned carbon-nanotube forests confined inside microfluidic channels for mechanically and/or chemically capturing particles ranging over three orders of magnitude in size.

The team placed various geometries of carbon nanotube forest into the microfluidic device. As in the original device, the surface of each tube can be coated 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 be caught. The scientists 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 micrometer in diameter, down to viruses, which are only 40 nm.

Circulating tumor cells (CTC), that have broken free from the original tumor are normally very hard to detect, because there are so few of them, usually only several cells per one mL of sample of blood, which normally contains billions of normal blood cells. By detecting these breakaway cells the physician can determine whether a cancer has metastasized. The scientists are now beginning to work on tailoring the device for human immunodeficiency virus (HIV) diagnosis. The original cancer-cell-detecting device is now being tested in several hospitals and may be commercially available within the next few years.

The scientists envisage the creation of new families of devices using this technique for a very broad range of applications. These include lab-on-a-chip devices for blood analysis to monitor patients at the point-of-care; ultra rapid cell sorters to detect rare cells in circulation for diagnostics, such as cancer, prenatal, and infections; high-throughput filters for pathogen depletion; and isolation of bacteria and viruses for diagnosing infectious diseases. The article describing the device was published online in March 17, 2011, in the journal Small.

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Massachusetts General Hospital
Massachusetts Institute of Technology