Our research focuses on the ultimate challenge in the design of biosensors: the ability to detect and study single molecules. By drawing on the properties of carbon nanotubes and advances in nanoscale fabrication and characterization, we are exploring new avenues for achieving single-molecule detection. As an example, every atom in a single-walled carbon nanotube lies on the nanotube’s surface and, therefore, surface adsorption of any molecule will alter the optical properties of the nanotube. Consequently, nanotube-based optical sensors are potentially capable of exquisite detection sensitivity at the molecular level. By using near-field optical scanning microscopy to characterize carbon-nanotube-DNA hybrids, we are quantifying the changes in the optical properties of carbon nanotubes that occur during the subtle biomolecular processes involved in molecular binding.

The main outcome we expect from this research will be development of optical DNA-detection methods that use oligonucleotide-functionalized carbon nanotubes as biosensors to provide real-time, label-free quantification of DNA and a straightforward approach to high-sensitivity and multiplexed detection of DNA. Along the way, we will cultivate a fundamental understanding of the interactions between nanoscale materials, such as carbon nanotubes, and biological molecules through the application of our combined skills in physics, chemistry and biology.