Rapid, sensitive, and non-destructive on-site quantitative detection of nanoplastics in aquatic environments using laser-backscattered fiber-embedded optofluidic chip.

A definitive link between the micro- and nano-plastics (NPLs) and human health has been firmly established, emphasizing the higher risks posed by NPLs. The urgent need for a rapid, non-destructive, and reliable method to quantify NPLs remains unmet with current detection techniques. To address this gap, a novel laser-backscattered fiber-embedded optofluidic chip (LFOC) was constructed for the rapid, sensitive, and non-destructive on-site quantitation of NPLs based on 180º laser-backscattered mechanism. Our theoretical and experimental findings reveal that the 180º laser-backscattered intensities of NPLs were directly proportional to their mass and particle number concentration. Using the LFOC, we have successfully detected polystyrene (PS) NPLSs of varying sizes, with a minimum detection limit of 0.23 μg/mL (equivalent to 5.23 ×10 particles/mL). Moreover, PS NPLs of different sizes can be readily differentiated through a simple membrane-filtering method. The LFOC also demonstrates high sensitivity in detecting other NPLs, such as polyethylene, polyethylene terephthalate, polypropylene, and polymethylmethacrylate. To validate its practical application, the LFOC was used to detect PS NPLs in various aquatic environments, exhibiting excellent accuracy, reproducibility, and reliability. The LFOC provides a simple, versatile, and efficient tool for direct, on-site, quantitative detection of NPLs in aquatic environments.