Effect of Surface Charge of Nanoparticles on Cellular Uptake in HeLa Cells

The surface charge of nanoparticles (NPs) is one of the major physicochemical factors for their interactions in biological systems. To improve the behavior of NPs in the cellular environment, there are numerous efforts to evaluate the effect on cellular uptake of the surface charge of NPs. In this study, we synthesized Pluronic block copolymer F127-based NPs by modifying both ends with phosphate (PP) to impart a negative charge and trimethylammonium bromide (AB) to confer a positive charge. By varying the ratios of PP-F127 and AB-F127, we produced NPs with a range of charge densities through the self-assembly method in aqueous solution, resulting in NPs with a semi-interpenetrating network structure in the core. The surface charge densities of NPs were characterized, and their cellular uptake was evaluated in HeLa cells. Our findings indicate that positively charged AB-NPs were internalized more efficiently into HeLa cells than negatively charged PP-NPs. These results highlight the importance of NP surface charge in determining cellular uptake, providing valuable insights for designing NP-based drug delivery systems.