|The prototype of the device is made of a widely used silicone|
rubber called polydimethylsiloxane and uses a technique
called 'on-chip immunoisolation.'
(Credit: University of Kansas/KU News Service)
Scientists have been laboring to detect cancer and a host of other diseases in people using promising new biomarkers called "exosomes." Indeed, Popular Science magazine named exosome-based cancer diagnostics one of the 20 breakthroughs that will shape the world this year. Exosomes could lead to less invasive, earlier detection of cancer, and sharply boost patients' odds of survival.
While the average piece of paper is about 100,000 nanometers thick, exosomes run just 30 to 150 nanometers in size. Because of this, exosomes are hard to separate out and test, requiring multiple-step ultracentrifugation, a tedious and inefficient process requires long stretches in the lab, according to scientists.
Now, researchers have published a breakthrough paper in the journal Lab On A Chip describing their invention of a miniaturized biomedical testing device for exosomes. The device promises faster result times, reduced costs, minimal sample demands and better sensitivity of analysis when compared to the conventional bench-top instruments now used to examine the tiny biomarkers.
The researchers have developed the device for early detection of lung cancer, the number-one cancer killer in the U.S. Today, lung cancer is detected mostly with an invasive biopsy, after tumors are larger than 3 centimeters in diameter and even metastatic, according to the researchers.Using the device, lung cancer could be detected much earlier, using only a small drop of a patient's blood.
The prototype of the device is made of a widely used silicone rubber called polydimethylsiloxane and uses a technique called "on-chip immunoisolation". They used magnetic beads of 3 micrometers in diameter to pull down the exosomes in plasma samples. In order to avoid other interfering species present in plasma, the bead surface was chemically modified with an antibody that recognizes and binds with a specific target protein, for example, a protein receptor, present on the exosome membrane. The plasma containing magnetic beads then flows through the microchannels on the diagnostic chip in which the beads can be readily collected using a magnet to extract circulating exosomes from the plasma.
Beyond lung cancer, the researchers believe the device could be used to detect a range of potentially deadly forms of cancer.