This research was designed to visualize cellular response – in particular the generation of intracellular ROS – to stimulation by polycyclic aromatic hydrocarbon (PAH). We used chloroauric acid (HAuCl4) as a molecular probe for visualizing intracellular ROS generated by the stimulation of benzo[a]pyrene (BaP). The chloroauric acid undergoes a spontaneous reduction reaction, assisted by the intracellular ROS, into gold nanoclusters (AuNCs).
As a result, we can visualize the ROS via optical imaging technique. According to MTT assay, the chloroauric acid exhibited good biocompatibility. The AuNCs produced in the cells were approximately 2–3 nm in diameter with a green fluorescent property. Cellular imaging showed that BaP induced the formation of AuNCs within the cells, leading to a high relative cellular fluorescent intensity with a considerable extent of scatter light. Thus, this probe is an efficient molecular imaging probe for visualizing intracellular ROS.