Towards more realistic reference microplastics and nanoplastics: preparation of polyethylene micro/nanoparticles with a biosurfactant

Microplastics are ubiquitous in the aquatic environment and polyethylene (PE) fragments are commonly identified in field samples. Studies are needed to evaluate the toxicity of microplastics, especially for the smallest ones that can be ingested by a wide range of organisms. However, due to a lack of preparation methods, small PE microplastics are not often used in laboratory studies. Here, a simple method was developed for the preparation of PE microparticles using dissolution of PE in toluene followed by emulsification in water. After complete evaporation of water and toluene, a powder of PE microparticles was obtained with radii between 0.2 to 0.80 m. The protocol could be optimized by adding surfactants like Tween 60 or Tween 80, and the possible use of a solution of microalgae exudates as a biosurfactant was also demonstrated. Planktonic crustaceans were exposed to different types of microparticles to evaluate their bioavailability depending on the surfactant.