Microglial response to gold nanoparticles

Given the emergence of nanotherapeutics and nanodiagnostics as key tools in today's medicine, it has become of critical importance to define precisely the interactions of nanomaterials with biological systems and to characterize the resulting cellular response. We report here the interactions of microglia and neurons with gold nanoparticles (GNPs) of three morphologies, spheres, rods, and urchins, coated with poly(ethylene glycol) (PEG) or cetyl trimethylammonium bromide (CTAB). Microglia are the resident immune cells of the brain, primarily involved in surveillance, macrophagy, and production of cytokines and trophic factors. Analysis by dark-field microscopy and by two-photon-induced luminescence (TPL) indicates that the exposure of neural cells to GNPs resulted in (i) GNP internalization by both microglial cells and primary hippocampal neurons, as revealed by dark-field microscopy and by two-photon-induced luminescence (TPL), (ii) transient toll-like receptor 2 (TLR-2) up-regulation in the olfactory bulb, after intranasal administration in transgenic mice, in vivo, in real time, [...