Surface and size effects on cell interaction of gold nanoparticles with both phagocytic and nonphagocytic cells

With the development of nanotechnology and its application in biomedicine, studies on the interaction between nanoparticles and cells have become increasingly important. To understand the surface and size effects on cell interaction of nanoparticles, the cellular uptake behaviors of two series of gold nanoparticles (AuNPs) with both positively and negatively charged surfaces and sizes range from ~16 to ~58 nm were investigated in both phagocytic RAW 264.7 and nonphagocytic HepG2 cells. The internalization of AuNPs was quantified by ICP-MS, and the intracellular fate of NPs was evaluated by TEM analysis. The results showed that the AuNPs with positive surface charge have much higher cell internalization ability than those with negative surface charge in nonphagocytic HepG2 cells. However, the uptake extent of negatively charged AuNPs was similar with that of the positively charged AuNPs when in phagocytic RAW 264.7 cells. Among the tested size range, negatively charged AuNPs with a diameter of ~40 nm had the highest uptake in both cells, while the positively charged AuNPs did not show a certain tendency. Intracellular TEM analysis demonstrated the different fate of AuNPs in different cells, where both the positively and negatively charged AuNPs were mainly trapped in the lysosomes in HepG2 cells, but many of them were localized in phagosomes when in RAW 264.7 cells. Cytotoxicity of these AuNPs was tested by both MTT and LDH assays, which suggested NP's toxicity is closely related to the tested cell types besides the surface and size of NPs. It demonstrates that cell interaction between nanoparticles and cells is not only affected by surface and size factors but also strongly depends on cell types.