Influences of size and surface coating of gold nanoparticles on inflammatory activation of macrophages.

The widely used engineered nanoparticles have presented non-negligible immunotoxicity and specific patterns of inflammatory-activating behaviors, which remain to be revealed in a more systematic way. In this work, gold nanoparticles (GNPs) with 3 different diameters were prepared, and then were further modified with poly(ethylene glycol) (PEG) or chicken ovalbumin (OVA) to achieve different surface properties. Both types of GNPs had sizes of 12, 35, and 60nm and possessed negatively charged surface, showing good colloidal stability in cell culture medium, respectively. The conjugated amount of OVA was around 110ng/mm2 regardless of the particle size. All the particles showed neglectable influence on viability of RAW246.7 macrophages when cocultured in vitro. The GNPs of larger size or conjugated with OVA were internalized with significantly larger amount. While the OVA-coated GNPs induced higher secretion of tumor necrosis factor-α, interleukin-6, and interleukin-1β, the PEG coating did not induce significant inflammatory response especially when the size of NPs was larger than 35nm. Comparatively, smaller GNPs induced stronger inflammatory responses regardless of their surface-conjugated molecules.