Organ-specific distribution of gold nanoparticles by their surface functionalization.

The behavior and fate of intravenously (i.v.) injected nanoparticles (NPs) can be controlled by several physicochemical factors including size, shape and surface charge. To evaluate the role of surface charge on distribution of NPs, we used neutral-charged 15-nm-sized polyethylene glycol-coated gold nanoparticles (AuNP(PEG)) as a core NP and carboxyl or amine groups were conjugated to AuNP(PEG) to generate negative (AuNP(COOH)) or positive AuNP (AuNP(NH2)), respectively. Each type of AuNP was i.v. injected into mice (1 mg kg(-1)) and the concentration of Au was measured in different organs at 30 min, 4, 24 h, 7, 14 days, 1, 3 and 6 months post-injection. The organ distribution also showed the higher deposition rate depending on their functional groups: AuNP(PEG) for mesenteric lymph node, kidney, brain and testis; AuNP(COOH) for liver; AuNP(NH2) for spleen, lung and heart. The blood circulation time and the major excretion route were different depending on their functional groups. In conclusion, functional groups conjugated on the surface of AuNPs produce differences in blood kinetics, organ distribution and elimination pattern which can be important information for directing NPs to specific organs or improving the kinetic properties.