Nanoparticle exposure in animals can be visualized in the skin and analyzed via skin biopsy

The increased manufacture and use of nanomaterials raises concerns about the long-term effects of chronic exposure on human health. However, nanoparticle exposure remains difficult to measure. Here we show that mice intravenously administered with high doses of gold nanoparticles have visibly blue skin while quantum dot-treated mice emit green, yellow, or red fluorescence after ultraviolet excitation. More importantly, elemental analysis of excised skin correlates with the injected dose and nanoparticle accumulation in the liver and spleen. We propose that the analysis of skin may be a strategy to quantify systemic nanoparticle exposure and can potentially predict the fate of nanoparticles in vivo. Our results further suggest that dermal accumulation may represent an additional route of nanoparticle toxicity and may be a future strategy to exploit ultra-violet and visible light-triggered therapeutics that are normally not useful in vivo because of the limited light penetration depth of these wavelengths.