Single molecule detection based on near-infrared sensors

Molecular detection using near-infrared light between 0.9 and 1.3eV has important environmental and biomedical applications because of greater light penetration into scattering media and reduced auto-fluorescent background from biological contaminants. Single Walled Carbon Nanotubes (SWNTs) have a tunable band-gap fluorescence in the near infrared that has been demonstrated to be sensitive to changes in their local dielectric function but remain stable to permanent photobleaching. In addition, it has been reported the synthesis and demonstration of several types of solution-phase, near-infrared sensors by functionalizing carbon nanotubes with ligands designed to modulate the fluorescence in response to selective molecular binding. This paper will focus the attention on the development of the current quasi-one-dimensional excitonic as observed on carbon nanotube photo-physics and describe a series of model sensor architectures that can be developed to built single-molecule sensors.