Visualizing nanoplastics-metal ions co-exposure stress with a NIR biothiols responsive fluorescent probe

Abstract

Visualizing the combined toxic effects of micro(nano)plastics and heavy metal ions remains challenging due to the lack of suitable in situ imaging tools, and current co-exposure models often simplify by simple mixing rather than using pre-formed complexes. In this work, a near-infrared biothiol fluorescent probe was developed based on naphthalimide scaffold with α,β-unsaturated acetyl group as recognition site. The probe exhibits high sensitivity and selectivity toward biothiols, and the detection limit was determined to be 0.47 μM for Cys, 0.37 μM for GSH, and 0.95 μM for Hcy, respectively. This enables to monitor biothiol fluctuations in living cells and zebrafish. Using pre-formed PMMA-Hg²⁺ complexes as co-exposure pollutant model, we investigated nanoplastics-metal ions complexes induced oxidative stress in living cells and zebrafish. Imaging results revealed that PMMA-Hg²⁺ complexes co-exposure induces distinct biothiol fluctuation patterns compared to single exposure of PMMA or Hg²⁺. The surface charge alteration of complexes and lysosomal function were found to be involved in the process. This study provides visualized evidence for elucidating the combined toxicity mechanisms of nanoplastic-heavy metal complexes co-exposure.