Identification, Quantification, and Imaging of the Biodistribution of Soot Particles by Mass Spectral Fingerprinting.

ABSTRACT

Soot is ubiquitous and has large detrimental effects on climate, air quality, and human health. However, identification of soot in carbonaceous media is very challenging due to its nanoscale carbon nature and complex sources. Due to the shortage in the methodology, until now, the fate and health effect of soot particles after inhalation are still poorly understood. Here, we report a new method for label-free identification, quantification, and imaging of soot particles in complex media based on laser desorption/ionization mass spectrometry fingerprinting. We found that soot particles from different origins and with different morphologies showed highly consistent mass spectral fingerprints deriving from peak ratios of small carbon cluster anions (C2--C10-), which enabled both accurate quantification of soot in fine particulate matter (PM2.5) samples and label-free imaging of soot particles in biological media. By using this technique, we tracked and imaged the suborgan distribution of soot particles in mice after exposure to PM2.5. The results showed that the lung is the main target organ for short-term inhalation exposure to soot particles. This study helps to better understand the inhalation toxicology of soot and also provides a practical novel methodological platform for identification, tracing, and toxicological studies of elemental carbon-based nanomaterials.