Some patients metabolize a certain drug quickly and others slowly. Because of this vast variance, there are drugs have not been introduced to the market because of the need for an immediate check of the blood level of the drug in order to prevent death. Plaxco explained that new drugs may be made available when this sensor is applied to this medical use.
To create the sensor, the researchers took a DNA molecule that converts from a floppy and unfolded shape into a structured, folded shape in the presence of cocaine. They then observe the change in the DNA by monitoring how electrons travel through it. There are DNA molecules available that bind to many different targets, so it follows that similar sensors can be easily made for other targets.
Currently the cocaine sensor that is widely used by police is the Scott test. When a chemical is added to the white powder it changes color. But there are many ways around this test, explained Plaxco, and some cocaine manufacturers add a chemical to block the color change. "Our sensor can detect cocaine no matter what they have cut it with: powdered sugar, flour, or the coffee that is sometimes used to mask the smell from dogs."
At this point the new sensor detects cocaine in the blood or saliva to a degree of a few micromolars. This is equivalent to the concentration of cocaine that would result from dropping a kilogram of cocaine into an olympic-sized swimming pool. That concentration would be the
Source:University of California - Santa Barbara