One- and two-photon fluorescent polyhedral oligosilsesquioxane (POSS) nanosensor arrays for the remote detection of analytes in clouds, in solution, and on surfaces

A series of polyhedral oligosilsesquioxane (POSS) nanosensors functionalized with fluorophores that change their wavelength of emission in response to their chemical environment has been synthesized and characterized by IR, NMR, UV, one- and two-dimensional fluorescence spectroscopy, MALDI-TOF MS, and electrospray MS. When each nanosensor in an array of n nanosensors is functionalized with a different wavelength shifting fluorophore, the array can generate a unique fingerprint comprised of n emission wavelength data points in response to a given chemical warfare agent (CWA) simulant or toxic industrial chemical (TIC). One-photon fluorescence fingerprints were constructed by measuring the fluorescence spectra of nanosensor-analyte pairs in solution. Two-photon fluorescence fingerprints were then generated by remotely interrogating nanosensor-analyte pairs using a femtosecond IR laser and a stand-off fluorimeter. Two-photon fingerprints were obtained for analytes in solution, on a surface, and in cloud form. A four-component nanosensor array could differentiate a homologous series of alcohols and distinguish G and VX classes of nerve agent simulants.