One of the most promising of these new detectors is being built by Charles Lieber, a chemist at Harvard University. In an article this month in Nature Biotechnology, he announced a highly-sensitive detector that can simultaneously find multiple cancer markers.
According to Lieber, the device, which uses nanowires to detect telltale cancer proteins, could lead to inexpensive and highly-accurate tests -- people could even buy them in a local drugstore and perform the testing themselves. "We can take a very small amount of blood and with a very simple filtration step get an answer within five minutes," Lieber says, adding that the device has "a sensitivity a thousand times better" than in a lab.
Lieber’s prototype builds on what University of California, Berkeley chemistry professor Paul Alivisatos has called "a breakthrough series of experiments." To detect specific cancer markers, Lieber attached a monoclonal antibody specific for a certain type of protein to nanowires each about as narrow as a virus. Some earlier experiments showed that changes in the conductivity of nanowires occurs when proteins bind to an antibody. The more proteins that bind, the more the conductivity changes, revealing the concentration of the protein.
Another benefit of the nanowire system is its flexibility. As new cancer markers are found, Lieber says, they could easily be incorporated into the device: "We could immediately take this new species and add that to our existing sensor."
Lieber’s method of measuring multiple biomarkers simultaneously has the potential to "diagnose the vast majority of people very accurately."
In fact, according to Lieber, the "biggest advantage" of the nanowire detectors is that they could detect "10 or 100 things in parallel" without adding cost to the test.
In talks with Lieber, oncologists have also suggested another application. Because the device gives results in real time, it could be used to monitor the effectiveness of cancer treatments. Right now, Lieber explains, the amount of drug a patient depends on his or her weight. Yet each person responds differently to different treatments. With such a nano-device, though, one could "fine-tune the dosage to make treatment much more effective."
Lieber and his research group have already tested the ability of the device to detect cancer markers in human blood -- a challenging task, since the target protein has a concentration around 100 billion times lower than the background proteins in serum. And they have also addressed some engineering issues with maintaining reliability.
How soon a cancer-detecting nano-device will be available depends, to a large extent, on developing the technology for mass production, according to Lieber, rather than with overcoming basic science obstacles.
So with molecular manufacturing: such tests will definitely be real time and for every person all the time. Enabling constant and detailed health monitoring.