Quantitation of superoxide radical (O 2–·) production at the site of radical generation remains challenging. A simple method to detect nanomolar to micromolar levels of superoxide radical in aqueous solution has been developed and optimized. This method is based on the efficient trapping of O2–· using a novel fluorescent probe (2‐chloro‐1,3‐dibenzothiazolinecyclohexene), coupled with a spectra character‐signaling increase event. A high‐specificity and high‐sensitivity fluorescent probe was synthesized in‐house and used to image O2–· in living cells. Better selectivity for O2–· over competing cellular reactive oxygen species and some biological compounds illustrates the advantages of our method. Under optimal conditions, the linear calibration range for superoxide anion radicals was 5.03 × 10−9−3.33 × 10−6 m. The detection limit was 1.68 × 10−9 m. Fluorescence images of probe‐stained macrophages stimulated with 4β‐phorbol 12‐myristate 13‐acetate were obtained successfully using a confocal laser scanning microscope.

In the present study, the cytotoxic effects and toxicological mechanism of six polybrominated diphenyl ethers (PBDEs) metabolites (3-OH-BDE47, 3-MeO-BDE47, 5-OH-BDE47, 5-MeO-BDE47, 6-OH-BDE85 and 6-MeO-BDE85) on L02 cells were explored by investigating the cell viability, apoptosis, lactic dehydrogenase (LDH) leakage, and oxidative stress response. The results showed that these metabolites could inhibit cell proliferation and induce apoptosis, among which 6-OH-BDE85 had the highest efficiency. LDH leakage test also showed that 6-OH-BDE85 had the strongest ability to cause LDH release. The reactive oxygen species (ROS) levels in 6-OH-BDE85- and 3-OH-BDE47-treated groups were significantly elevated in a dose-dependent manner. After treatment for 24 h, four BDE47 metabolites (3-OH-BDE47, 3-MeO-BDE47, 5-OH-BDE47, and 5-MeO-BDE47) induced an increase in superoxide dismutase (SOD) activity and decrease in glutathione (GSH) level, whereas 6-OH-BDE85 led to a decrease in both SOD activity and GSH level. These effects disappeared after continued culturing for another 24 h. In conclusion, these PBDE metabolites, especially 6-OH-BDE85, showed cytotoxicity on L02 cells, which was at least partially related to the oxidative stress level.