Real-time visualization of perylene nanoclusters in water and their partitioning to graphene surface and macrophage cells

Importance of the work and objectives Hydrophobic organic chemicals (HOCs) are of special ecotoxicological concern because they can be directly incorporated and bio-concentrated in living organisms. However, the effects of... [ view full abstract ]

Importance of the work and objectives
Hydrophobic organic chemicals (HOCs) are of special ecotoxicological concern because they can be directly incorporated and bio-concentrated in living organisms. However, the effects of self-clustering of HOCs on their environmental behavior and toxicology have not yet received enough attention. The behavior of HOCs in cluster form is quite different from those in single molecular form. HOCs distributing in the environmental systems in the form of nano-clusters may have significant implications for understanding their environmental fate and potential toxicological effects.
Methodologies
With the use of a recently developed technique, single-molecule fluorescence microscopy (Zeiss, Axio Observer), the adsorption of perylene nano-clusters (PNCs) onto carbonaceous surface and the transport of PNCs across the cell membrane were visualized with high temporal and spatial resolution. Perylene clusters were excited by a 405 nm laser (Coherent OBIS 405), and monitored with the filter set (dichroic mirror 405 nm, emission 570-640 nm). The fluorescent emission was collected by an 100× oil-immersion objective with numerical aperture of 1.46 and imaged onto an electron multiplying charge coupled device (EMCCD) camera (Photometrics, Evolve 512).
Main results and conclusion
We showed the characteristic of irreversible adsorption of perylene in the form of nano-clusters onto carbonaceous surfaces, exhibiting random sequential ‘car-parking’ events.
PNCs can enter macrophage cells by endocytosis. The uptake of HOCs in the form of nano-clusters by endocytosis was proposed to be an additional but important mechanism for their bio-concentrating into living cells.