Tetra-ethylene glycol coated gold nanoparticles are stable and have an extended half-life in vivo (2016)

Undergraduates: Julian Willett, Dr. Marlon Lawrence, Jen Wilder, Dr. Oliver Smithies

Faculty Advisor: Oliver Smithies
Department: Biology

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I investigated a little-studied nanoparticle coating, tetra-ethylene glycol (TEG), to determine if this compound provides pharmacologically-relevant advantages, such as increased serum half-life and resistance to protein adsorption. I compared results to particles with a glutathione (GSH) coating, which we have found to be unaltered in circulation and readily excreted renally. Nanoparticles coated with GSH and TEG were intravenously injected into mice and their half-life and final destination determined via photometric analysis and light microscopy, respectively. Protein adsorption, which facilitates macrophage phagocytosis of nanoparticles, was studied via column chromatography and transmission electron microscopy (TEM). GSH-coated particles had a shorter half-life than TEGylated particles and predominantly accumulated in the kidney and urine with TEGylated particles gathering in the spleen and kidney. TEGylated particles were likely not in the urine as they had a slower glomerular filtration rate, facilitating their reabsorption by proximal convoluted tubule cells. Despite their filtration and reabsorption, TEGylated particles remained stable, as TEM revealed no circulating particle aggregates and column chromatography revealed no change. These results demonstrate TEGylated nanoparticles have increased serum half-life and resistance to protein adsorption despite a smaller coat size. This suggests TEG could be an alternative to currently used coating agents.