PET Tracing of Biodistribution for Orally Administered ⁶⁴Cu-Labeled Polystyrene in Mice

Plastics are used commonly in the world because of their convenience and cost effectiveness. Microplastics, an environmental threat and human health risk, are widely detected in food and consequently ingested. However, degraded plastics are found everywhere, creating an environmental threat and human health risk. Therefore, real-time monitoring of orally administered microplastics to trace them in the body is tremendously important. Methods: In this study, to visualize their absorption path, we labeled polystyrene with [⁶⁴Cu]Cu-DOTA. We prepared radiolabeled polystyrene with ⁶⁴Cu. Afterward, [⁶⁴Cu]Cu-DOTA-polystyrene was orally administered to mice, and we evaluated its transit and absorption using PET imaging. The absorption path and distribution of [⁶⁴Cu]Cu-DOTA-polystyrene were determined using PET over 48 h. Ex vivo tissue radio-thin-layer chromatography (TLC) was used to demonstrate the existence of [⁶⁴Cu]Cu-DOTA-polystyrene in tissue. Results: PET images demonstrated that [⁶⁴Cu]Cu-DOTA-polystyrene began to transit to the intestine within 1 h. Accumulation of [⁶⁴Cu]Cu-DOTA-polystyrene in the liver was also observed. The biodistribution of [⁶⁴Cu]Cu-DOTA-polystyrene confirmed the distribution of [⁶⁴Cu]Cu-DOTA-polystyrene observed on the PET images. Ex vivo radio-TLC demonstrated that the detected γ-rays originated from [⁶⁴Cu]Cu-DOTA-polystyrene. Conclusion: This study provided PET evidence of the existence and accumulation of microplastics in tissue and cross-confirmed the PET findings by ex vivo radio-TLC. This information may be used as the basis for future studies on the toxicity of microplastics.