Gold nanoparticles (GNP) provide many opportunities in imaging, diagnostics, and therapies of nanomedicine. Hence, their biokinetics in the body are prerequisites for specific tailoring of nanomedicinal applications and for a comprehensive risk assessment.We administered 198Au-radio-labelled monodisperse, negatively charged GNP of five different sizes (1.4, 5, 18, 80, 200nm) and 2.8nm GNP with opposite surface charges by intravenous injection into rats. After 24 h the biodistribution of the GNP was quantitatively measured by gamma-spectrometry.The size and surface charge of GNP strongly determine the biodistribution. Most GNP accumulated in the liver increased from 50% of 1.4nm GNP to > 99% of 200nm GNP. In contrast, there was little size dependent accumulation of 18nm to 200nm GNP in most other organs. However, for GNP between 1.4nm and 5nm the accumulation increased sharply with decreasing size; i.e. a linear increase with the volumetric specific surface area. The differently charged 2.8nm GNP led to significantly different accumulations in several organs.We conclude that the alterations of accumulation in the various organs and tissues, depending on GNP size and surface charge, are mediated by dynamic protein binding and exchange. A better understanding of these mechanisms will improve drug delivery and dose estimates used in risk assessment.
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