DNA-decorated carbon nanotubes for chemical and biological sensing

We demonstrate a new, versatile class of nanoscale chemical sensors based on single-stranded DNA (ssDNA) as the chemical recognition site and single-walled carbon nanotube field effect transistors (swCN FETs) as the electronic read-out component. swCN FETs with a nanoscale coating of ssDNA respond to gas odors that do not cause a detectable conductivity change in bare devices. Responses of DNA-deocrated FETs differ in sign and magnitude for different gases, and can be tuned by choosing the base sequence of the ssDNA. These sensors detect a variety of odors, with rapid response and recovery times on the scale of seconds. The sensor surface is self-regenerating: samples maintain a constant response with no need for sensor refreshing through at least 50 gas exposure cycles. This remarkable set of attributes makes sensors based on ss-DNA decorated nanotubes very promising for "electronic nose" and "electronic tongue" applications ranging from homeland security to disease diagnosis.