Autofluorescence of atmospheric bioaerosols – fluorescent biomolecules and potential interferences

[摘要] Primary biological aerosol particles (PBAP) are an important subset of airparticulate matter with a substantial contribution to the organic aerosolfraction and potentially strong effects on public health and climate. Recentprogress has been made in PBAP quantification by utilizing real-timebioaerosol detectors based on the principle that specific organic moleculesof biological origin such as proteins, coenzymes, cell wall compounds andpigments exhibit intrinsic fluorescence. The properties of many fluorophoreshave been well documented, but it is unclear which are most relevant fordetection of atmospheric PBAP. The present study provides a systematicsynthesis of literature data on potentially relevant biologicalfluorophores. We analyze and discuss their relative importance for thedetection of fluorescent biological aerosol particles (FBAP) by onlineinstrumentation for atmospheric measurements such as the ultravioletaerodynamic particle sizer (UV-APS) or the wide issue bioaerosol sensor(WIBS).

In addition, we provide new laboratory measurement data for selectedcompounds using bench-top fluorescence spectroscopy. Relevant biologicalmaterials were chosen for comparison with existing literature data and tofill in gaps of understanding. The excitation-emission matrices (EEM)exhibit pronounced peaks at excitation wavelengths of ~280 nm and~360 nm, confirming the suitability of light sources used for onlinedetection of FBAP. They also show, however, that valuable information ismissed by instruments that do not record full emission spectra at multiplewavelengths of excitation, and co-occurrence of multiple fluorophores withina detected sample will likely confound detailed molecular analysis. Selectednon-biological materials were also analyzed to assess their possibleinfluence on FBAP detection and generally exhibit only low levels ofbackground-corrected fluorescent emission. This study strengthens thehypothesis that ambient supermicron particle fluorescence in wavelengthranges used for most FBAP instruments is likely to be dominated bybiological material and that such instrumentation is able to discriminatebetween FBAP and non-biological material in many situations. More detailedfollow-up studies on single particle fluorescence are still required toreduce these uncertainties further, however.

[学科分类] 几何与拓扑