The nanometer-thick carbon nanotubes naturally glow or fluoresce when exposed to laser light, but in order to turn them into sensors, the research team had to first coat them with materials that can bind to target molecules. In this case, the researchers coated the nanotubes with chains of DNA called aptamers. When the target molecule binds to the DNA chains, the nanotube's glow changes in a measurable way. The "sensor array" can be set up on a microscope slide and when a bacteria, yeast or human cell is placed inside the array, the sensors will detect the presence of the target protein.
Although the researchers have only tested the system with two different proteins so far, they believe the system could lead to new breakthroughs in biopharmaceutical treatments as well. Other researchers are already working on ways to re-engineer a patient's own cells to secrete beneficial proteins and the new MIT sensor array system would be crucial to testing those treatments, as well as studying viruses, neurotransmitters and quorum sensing -- the process by which bacteria colonies communicate.