A smartphone-based portable fluorescence sensor Utilizing carbon dots for semi-quantification of Microgram-scale microplastics

Developing facile analytical methods and portable instruments to quantify existence of microplastics (MPs) in environmental samples is demanding but remains challenging. In this study, a method exploiting carbon dots (CDs) as fluorescence source and XRD quartz plate as substrate was proposed for semi-quantitative MPs based on fluorescence “turn on” strategy. After excitation at 365 nm, non-fluorescence CDs film was brightened with yellow emission in the presence of polyethylene (PE) MPs due to the surface environment change of CDs. For realizing facile detection, smartphone and ImageJ software were used to capture the fluorescence signals of the CDs film. A linear curve was fitted to be y = 0.31627 x + 0.77396 with a linear range of 2–22 μg. Furthermore, the method was further applied on water samples to demonstrate its sensing capability. Finally, a portable sensor involving this analytical method was proposed. This work not only presents a facile analytical method for quantification of PE MPs, but also provides a tool to apply in the field of MPs management.