Investigation of a Method for Fluorescently Labeling Polyethylene and Polypropylene Nanoplastic Particles for Biological Impact Assessment Research.

Micro- and nanoplastics, which raise concerns due to their potential impact on living organisms, exist in diverse forms and undergo surface chemical degradation through ultraviolet (UV) irradiation and other environmental factors. To provide a more realistic evaluation of their biological effects, we prepared nanoparticles of polyethylene (PE) and polypropylene (PP)-two of the most abundant plastics in the environment-and simulated their degradation by exposing them to UV light. Furthermore, to enable assessment of biological effects, we investigated fluorescent labeling using a tetrahydrofuran-based (THF) swelling-and-incorporation method. By employing the highly hydrophobic dye BODIPY and refining the staining procedure to include THF evaporation, we successfully achieved stable fluorescent labeling of both undegraded and UV-degraded PE and PP particles. Notably, the fluorescence remained intact even after washing with organic solvents capable of dissolving the dye. This robust staining technique thus provides a valuable platform for investigating the biological effects of plastic nanoparticles.