Polydopamine (PDA) Functionalized Eutectic Gallium–Indium (EGaIn) Nanoparticles as a Distortable Fluorescent Sensor for Pb²⁺ Detection

Fluorescent nanoparticles offer promising applications for bioimaging due to their exceptional attributes, including heightened fluorescence brightness and prolonged photo-stability, surpassing those of traditional fluorescent dyes. However, the selection of suitable materials and surface functionalization strategies for the synthesis of efficient fluorescent nanoparticles remains a significant challenge in this field. Here, we report a facile synthesis method of fluorescent nanoparticles, which is rationally designed by coating polydopamine (PDA) on eutectic Gallium-Indium (EGaIn, a liquid metal (LM)) under ultrasonic waves to prepare the fluorescent PDA/LM nanoparticles. The fluorescence intensity of the PDA/LM nanoparticles is eightfold greater than that of the pristine PDA nanoparticles and can be quenched by Pb²⁺. It demonstrates that the PDA/LM nanoparticles exhibit superior analytical performance for Pb²⁺ over a linear range from 10 to 100 µg/L, with a detection limit of 3 µg/L. This probe can be used to detect Pb²⁺ in different vessels.