Characterization of the physicochemical properties of Polystyrene Nanoparticles v1

This protocol describes the physicochemical characterization of amine-modified (positively charged) and carboxylate-modified (negatively charged) fluorescent polystyrene nanoparticles (PS-NPs). The purpose is to determine particle size distribution, surface charge (z-potential), morphology, and fluorescence properties prior to biological experiments. These parameters are critical for interpreting uptake behavior and toxicity in vitro and in vivo. Results: Surface charge is a critical parameter for toxicity.