Prof. Chang and FCubed in Chicago Sun Times
Anne Veselik • DATE: November 30, 2012
"Entering new waters via tiny chip" article by Sandra Guy appeared in the Chicago Sun Times on November 12, 2012.
Prof Chang's lab, the Center for Microfluidics and Medical Diagnostics, invented the Carbon Nanotube Sensor for the first portable nucleic acid (DNA and RNA) diagnostic device now being produced by FCubed, LLC. Pathogen (bacteria and virus) detection can only be very specific if their RNA and DNA are identified. This is currently done with optical sensing technologies like real-time PCR (Polymerase Chain Reaction) and DNA microarrays in hospitals.
While such optical nucleic acid sensing technologies are very sensitive, they suffer from two major drawbacks-they are slow because of the low diffusivity of the large nucleic acid molecules and they are very expensive. Both drawbacks have limited the development of portable nucleic acid sensors, like the glucose sensor for diabetics, that can be used outside of a hospital. Traditional electrochemical sensing technologies for chemicals like glucose, which are based on electron-transfer currents to metal electrodes, do not work well for nucleic acids. Prof Chang's group led by Dr. Senapati (a research professor in his lab) and Sagnik Basuray (a PhD student now with Roche diagnostics), with some assistance by an earlier PhD student Zachary Gagnon (now on the faculty at Johns Hopkins), optimized a chemically inactive carbon nanotube sensor so that it offers the necessary sensitivity and selectivity for nucleic acids. The invention involves direct loading of the carbon nanotube sensors onto upporting electrodes by dielectrophoresis, a phenomenon due to induced alternating-current dipoles that Professor Chang's group has studied both theoretically and experimentally for a decade, and is hence much cheaper than the earlier technology of growing them on the electrodes by Chemical Vapor Deposition.
The large aspect ratio of the conducting nanotubes also imparts a large and attractive dielectrophoretic force on the target nucleic acids, such that they are transported to the sensors much more rapidly than by diffusion. The invention hence overcomes both the diffusion limitation and cost constraint of other nucleic acid sensors. FCubed LLC has licensed this technology from Notre Dame and had worked with Prof Chang's lab in the last two years to produce this first commercial portable nucleic acid sensor. FCubed's strategy is to enter the smaller markets like food safety, third world infectious disease control and environmental monitoring first. It is working with the Notre Dame Haiti program and also with the EPA on recreational water monitoring. It is also positioning itself for the much larger developed world medical market with more stringent FDA regulatory requirements. For the developed world market, Prof Chang's laboratory is working on multi-target sensors for profiling human host microRNAs and proteins for home-use early diagnostics for cancer and cardiovascular diseases. FCubed LLC is working with Prof Chang's lab on some of these efforts and may license the second-stage technologies once they are more mature. The next technology is ready to be licensed for development within a year.