While adverse health effects of particulate matter exposure are a generally accepted concern, locating and tracking these nanometer sized particles is in its infant state. Measurements in polluted air such as absorption photometry and laser induced incandescence (LII) have so far been used to determine particle concentrations, alternatively labeling methods have been applied in epidemiological and toxicology research.<br/>In this paper we present a direct, label-free technique to detect carbon nanoparticles in fluids and cells by laser induced white-light generation as well as using pump-probe microscopy. We demonstrate non-incandescence related white-light (WL) generation by dry and suspended carbon black particles (CB) under illumination with femtosecond pulsed near-infrared light (780 nm - 950 nm, 150 fs, 80 MHz). Since the emissive response is instantaneous, we attribute this mechanism to multiphoton ionizations and consecutive transitions, leading to an emission spreading over the whole visible spectrum (Figure). This WL emission allows optical detection and unequivocal localization of CB particles in fluids and in cellular environments while simultaneously co-localizing different labelled cellular components e.g. in human lung fibroblasts. The experiments can be performed on a typical multiphoton laser-scanning microscopy platform. Complementary to this approach, pump-probe imaging, directly interrogating the strong particle absorption will be demonstrated.

Advanced optical detection of carbon nanoparticulates to measure exposure in a biomedical setting

254th National Meeting (2017)

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