Effects of Gold Nanoparticles with Different Surface Charges on Cellular Internalization and Cytokine Responses in Monocytes

Surface modification of gold nanoparticles (AuNPs) affects the interactions between the AuNPs and biological systems. To use AuNPs in biomedical applications, an investigation of how different surface charges of AuNPs affect the internalization mechanisms and functions of monocytes is needed. In this study, U937 cells were exposed to AuNPs with positive (AuNPs+ve) and negative (AuNPs-ve) surface charges. Cellular responses to the AuNPs, including cell uptake pathways, cell activation and cytokine production, were analysed. The results indicated different responses to AuNPs-ve and AuNPs+ve in outcomes including internalization pathways, cell activation and cytokine production levels. Interestingly, the results suggested that AuNPs+ve tended to enter the cells via macropinocytosis and strongly elicited a cellular response of IL-6 production via NF-kB activation, whereas the AuNPs-ve suppressed IL-6 production. Therefore, these results provide essential information for designing nanoparticles and may contribute to possible future nanomedicine applications, such as drug delivery and vaccination.