Investigation into the intracellular dynamics of micro- and nanoplastics

<p>Microplastics (MPs) are plastic particles with a diameter of 5 mm or less, and those with a diameter of 1 µm or less are specifically defined as Nanoplastics (NPs). These plastic particles are ubiquitous in the environment. Recent studies have shown that MPs/NPs were detected in human body, indicating unavoidable exposure for humans. It is also known that MPs/NPs in the environment undergo degradation due to ultraviolet rays and waves, leading to changes in physical properties such as size and surface properties. Although the kinetics of tiny particles vary depending on their physical properties, the effects of these differences in MPs/NPs are not yet clarified. In this study, we tried to elucidate the intracellular dynamics of MPs/NPs focusing on the surface degradation of them.</p><p>First, we prepared degraded polyethylene (d-PE) by exposing ultraviolet rays to PE. Next, RAW264.7（mouse macrophage-like cell line）were exposed to PE or d-PE and SSC (side scatter) was measured by Flow Cytometry. As a result, an increasing trend was observed in the d-PE-treated group. In addition, we prepared fluorescent-labeled PE and d-PE using NileRed, a fluorescent dye that emits green fluorescence in response to hydrophobic groups and red fluorescence when hydrophilicity increases. THP-1, (human monocyte cell line）was exposed to them to evaluate cellular uptake. Fluorescence microscopy observation revealed that the fluorescent-labeled d-PE was either adhered to or incorporated into the cells. Now, we are working on establishing a method for quantifying the intracellular uptake of MPs/NPs.</p>