Synthetic microplastic beads

First, the samples were imaged using the imaging flow cytometry (Amnis® ImageStream®X Mk II). Bioparticles such as Cryptosporidium, Giardia, microplastics and other pollutants such as dirt and cell debris with size ranging from 3 to 14 μm that naturally exist in drinking water were included in the study. The naturally existing pollutants were obtained by concentrating 10 litres of drinking water using a water filtration system. Formalin-treated Cryptosporidium oocysts, Giardia cysts (Waterborne™ Inc.) and synthetic microplastic beads (Thermo Fisher Scientific, Duke Scientific and Polysciences Inc.) of different sizes (1.54 μm, 3 μm, 4 μm, 4.6 μm, 5 μm, 5.64 μm, 8 μm, 10 μm, 12 μm and 15 μm) were spiked separately in 200 μL water. Bioparticles were hydrodynamically focused by a sheath flow and flowed through the detection region with phosphate buffered saline solution (PBS) used as the sheath medium. Single bioparticles were illuminated with an LED light source, and brightfield images (Fig. 4) were acquired with a charge-coupled device (CCD) camera²⁴ using a 60× objective in Fig. 3(a).