A potent fluorescent probe for HOCl with dual NIR emissions: Achieving the early diagnosis of polystyrene microplastics-induced liver injury involved in ferroptosis

Polystyrene microplastics (PS-MPs) are ubiquitous environmental contaminants that pose a significant threat to ecosystems and human health. The toxicity of PS-MPs to the liver is associated with a surge of reactive oxygen species (ROS). However, the specific type of ROS triggered by PS-MPs in the injured liver tissue remains inadequately known. In this study, a dual-channel near-infrared (NIR) fluorescent probe TPAC-B with distinct aggregation-induced emission (AIE) properties was contructed, which can specifically detect HOCl and target dual organelles (mitochondria and lipid droplets). Firstly, TPAC-B exhibited selective detection of HOCl with dual-channel imaging in PS-MPs-treated cells, thus eliciting a 40-fold ratiometric fluorescence enhancement. Probe TPAC-B was also prone to accumulate in the liver, and real-time monitoring of elevated HOCl levels in a mouse model of PS-MPs-induced liver injury was thus achieved. As confirmed by western blot analysis, PS-MPs could suppress the expression of ferroptosis regulatory proteins glutathione peroxidase 4 (GPX4) and Ferritin in liver cells and upregulate the expression of heme oxygenase-1 (HO-1, a marker protein for oxidative stress). Therefore, the work shown here represents the first fluorescent probe capable of tracking the fluctuation of HOCl levels in PS-MPs-induced liver injury, providing a potent imaging tool for the early diagnosis of this disease.