Fluorescent molecular rotor-based probes for sensitive and selective detection of nanoplastics in food, environment, and living cells

Two molecular rotor-based fluorescent probes, TPAP (Triphenylamine with a positive charge) and TPAN (Triphenylamine with a negative charge), were developed for detecting functionalized nanoplastics (NPs) with different surface charges. Leveraging the hydrophobicity and surface charge interactions, TPAP and TPAN demonstrated high sensitivity and excellent specificity for two functionalized polystyrene NPs, sulfonated polystyrene (PS-SO₃H) and amino-modified polystyrene (PS-NH₂), achieving detection limits of 19.3 and 57 ng/mL, respectively. Furthermore, TPAP-loaded strips integrated with a smartphone-based color analysis platform were developed, enabling on-site and visual quantification of functionalized NPs in environmental soil and water samples. Spike-and-recovery experiments confirmed the accuracy of this method for detecting functionalized NPs in vegetables, beverages, plastic packaging and water, with recoveries ranging from 96.80 ± 1.32 % to 105.93 ± 3.78 % and relative standard deviations of 0.89 %-4.37 %. Finally, both TPAP and TPAN were successfully applied to bioimaging in human cardiomyocytes, providing a potent visual tool for investigating surface-functionalized NPs behavior in biological systems.