In vitro cellular uptake of polystyrene nanoparticles: effect of particle size and surface functional group

Abstract

Polymer nanoparticles have been actively studied as a potential drug delivery system. Study on their cellular uptake behavior is essential for designing intra-cellular drug delivery systems. Important characteristics determining cellular uptake of polymer nanoparticles could be their sizes and functional groups. In this study, we have investigated the in vitro cellular internalization of polystyrene (PS) nanoparticles with different sizes (50, 100 and 500 nm) and different surface functional groups (carboxyl, amine and sulfate groups) using NIH3T3 (mouse fibroblast cell line) as a model cell. The cellular internalization of PS nanoparticles were monitored by flow cytometry and confocal microscopy. The rate and amount of cellular uptake were significantly dependent on the particle size. The initial uptake rate of nanoparticles into NIH3T3 was greatly dependent on the particle size: the nanoparticle with a mean diameter of 100 nm showed much faster cellular internalization when compared to ones of 500 nm. According to the functional groups at the same size of 100 nm, the uptake rate of PS nanoparticles with surface carboxyl group was remarkably higher than ones with amine and sulfate groups. Overall results imply that more detailed study should be needed to elucidate the effect of surface charge on the rate of cellular uptake with different polymer nanoparticles and cell lines.