NIRT: Single molecule detection in living cells using carbon nanotube optical probes

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0708459Strano This proposal was received in response to the Active Nanostructures and Nanosystems initiative, NSF 306-595, category NIRT. This proposal seeks to demonstrate real time, sustained optical signal transduction from living cells at the single molecule level. Nanotechnology is yielding new classes of materials with unique optical properties that can provide innovative engineering solutions to traditionally difficult biological problems. While single molecule detection techniques have significantly impacted our understanding of biology, limitations such as photobleaching, intermittent emission (blinking), unfavorable wavelengths and auto-fluorescence have restricted in-vitro and in-vivo single molecule studies to superficial regions of biological systems. The high electronic density of states of carbon nanotubes enables their spectroscopic characterization at the single nanotube level. Hence, it is now theoretically possible to transduce single molecule adsorption events at a nanotube surface. Furthermore, carbon nanotubes are unique in that they do not photo-bleach, show no intermittent blinking and are detectable at the single molecule level in the near infrared, where auto-fluorescent background is negligible. In this proposal, the research team will demonstrates the engineering of single walled carbon nanotubes by attaching recognition ligands, which modulate the optical properties in response to a specific molecular adsorption. Preliminary data has been shown for ultra sensitive detection of glucose and streptavidin using prototype carbon nanotube-based optical probes. In addition, the PI demonstrates that wrapping DNA oligonucliotides and other biomolecules around nanotube sensors can deliver them directly into the cytoplasm of murine myoblast stem cells. Thus they present, as proof of concept, the first nanotube spectroscopy from within a living cell.