Single-molecule optical detection of nitroaromatic compounds by carbon nanotubes

Biopolymer-encapsulated single-walled carbon nanotubes (SWNT) recognize specific nitroarom. mols. via either a wavelength or intensity change of near IR photoluminescence. A class of peptides from the bombolitin family not previously identified for nitroarom. recognition allows the carbon nanotube around which they are encapsulated to report changes in their conformation, 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 nitroaroms. These interactions are probed for the first time at the single mol. level, as stochastic adsorption and desorption events are optically reported by the SWNT. A novel dual-channel single-mol. imaging microscope is demonstrated to image quantized spectral shifts in real-time, resulting in the first single-mol. stochastic detection of solvatochromic events. [on SciFinder(R)]