Combustion-formed particulate matter with dimensions in the micrometer scale has been studied and shown to be a known cause of oxidative stress in cells. However, particulate matter in the ultrafine region (&lt;100 nm) needs much more study, both as individual causal agents and as components of particulate matter as a whole. Black carbon (BC) is a known component of particulate matter &lt;100 nm, and BC has been declared a health threat by the World Health Organization. BC has also been defined as a substance that needs further investigation to understand its independent impact on the human body, in particular, the lower respiratory tract. Creation of trackable BC surrogates would not only permit following their transport and fate within the respiratory system, but also allow for study of the biological effects of individual components of particulate matter. Fluorescent carbon dots (FCDs) that act as surrogates for BC have the potential to offer these valuable insights. Described here are well-defined routes for synthesizing FCDs/BC surrogates with distinct optical properties that are shown to be related to the structural properties of FCDs. Through the use of analytical and structural techniques, the fluorescence quenching and recovery behaviors of FCDs are studied upon FCD exposure to solution-phase stimuli, giving valuable information on the fluorescence mechanism of the particles. In particular, the role of synthetic conditions on the fluorescence behavior and the structural properties of isolated FCDs is defined and discussed here. Subsequent changes in structure are readily related to the nature of the solution-phase stimulus used to effect fluorescence from the BC surrogates. By exposing human lung epithelial (BEAS-2B) cells to the well-characterized FCDs, the influence on and ultimate destination of BC in lung cells are defined. Use of the FCDs as BC mimics allows for a comprehensive study of FCDs and their properties from creation to dissemination, allowing for more strategic design through the understanding of their physical properties, as well as their impact on cells.

Fluorescent black carbon surrogates: Probing biological impacts of black carbon while relating form and function in creating fluorescent carbon dots

2019 Fall National Meeting

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