Size distribution analysis and physical/fluorescence characterization of graphene oxide sheets by flow cytometry

Abstract

Flow cytometry is presented here as an alternative tool for analysis of size distribution and intrinsic fluorescence of graphene oxide (GO) sheets. Unlike other nanoparticles, GO sheets induced scatter signals reasonably distinct from the background noise of the system. The number of gated signals generated by the sheets was proportional to GO concentration, indicating that non-spherical particles like GO can be convincingly studied by flow cytometry. The asymmetry in forward scatter-side scatter contour plots was consistent with a non-uniform size distribution of individual sheets in the population, which contrasted with a prototype animal cell population. GO was endowed with intrinsic fluorescence detectable through the three fluorescence channels in the cytometer and allowed comparison of relative fluorescence intensities associated with individual sheets. Flow cytometry thus provides rapid access to high-dimension statistical information on individual GO sheets that is not achievable with existing characterization tools, and may prove to be an indispensable tool in graphene research.