(262b) Single-Molecule Detection of Nitroaromatic Compounds by Carbon Nanotube Optical Sensors
Polymer-encapsulated single-walled carbon nanotubes (SWNT) detect nitroaromatic compounds at the single-molecule with high selectivity and species recognition. A class of peptides from the bombolitin family not previously identified for nitroaromatic recognition allows the carbon nanotube around which they are encapsulated to report changes in their secondary structure, forming a ?chaperone sensor.' Analyte identification is afforded by spectroscopically differentiable changes of eight (n,m) SWNT species which generates a unique spectral fingerprint. An oligonucleotide d(AT)15 enables high selectivity for trinitrotoluene to the exclusion of other nitroaromatics. These interactions are probed for the first time at the single molecule level, as stochastic adsorption and desorption events are optically reported by the SWNT as intensity or wavelength fluctuations. A novel dual-channel single-molecule imaging microscope is demonstrated to image quantized spectral shifts in real-time, resulting in the first single-molecule stochastic detection of solvatochromic events.