Identification of Nanoplastics by Probing the Viscous Nanoenvironment

With the growing prevalence of global microplastic and nanoplastic pollution, the accumulation of nanoplastics in the human body has increased, heightening the risk of noncommunicable diseases including cancer, cardiovascular disease, and amyotrophic lateral sclerosis. However, the development of fluorescent probes for detecting nanoplastics remains challenging due to the lack of reactive sites on nanoplastics for conventional design of responsive probes. In this work, a novel strategy for the sensitive detection of nanoplastics by probing the viscous nanoenvironment surrounding them is presented. This study synthesizes a cationic fluorescent probe, Purification by silica gel column chromatography (CH₂Cl₂/MeOH) provided (E)-2-(2-(4-(dimethylamino)nanphthalen-1-yl)vinyl)-1,3,3-trimethyl-3H-indol-1-ium (named HCY due to its structural similarity to hemicyanine dyes) as a tawny solid (HCY), via a simple one-step reaction. HCY demonstrates high sensitivity to nanoplastics, achieving an 8.5-fold fluorescence enhancement in the presence of carboxylated polystyrene nanoplastics, with a detection limit of 0.153 μg mL^-1. Moreover, HCY exhibits excellent biocompatibility, enabling the monitoring of nanoplastics level in living cells and visualization of nanoplastics distribution in zebrafish. This work offers a new design strategy for responsive fluorescent probes and provides a promising avenue for detecting environmental pollutants.