Uptake of bright fluorophore core-silica shell nanoparticles by biological systems

Andrew Zane,¹ Christie McCracken,² Deborah A Knight,² Tanya Young,¹ Anthony D Lutton,³ John W Olesik,³ W James Waldman,² Prabir K Dutta<sup>1

1</sup>Department of Chemistry and Biochemistry, ²Department of Pathology, ³School of Earth Sciences, The Ohio State University, Columbus, OH, USA

Abstract: Nanoparticles are used in a variety of consumer applications. Silica nanoparticles in particular are common, including as a component of foods. There are concerns that ingested nanosilica particles can cross the intestinal epithelium, enter the circulation, and accumulate in tissues and organs. Thus, tracking these particles is of interest, and fluorescence spectroscopic methods are well-suited for this purpose. However, nanosilica is not fluorescent. In this article, we focus on core-silica shell nanoparticles, using fluorescent Rhodamine 6G, Rhodamine 800, or CdSe/CdS/ZnS quantum dots as the core. These stable fluorophore/silica nanoparticles had surface characteristics similar to those of commercial silica particles. Thus, they were used as model particles to examine internalization by cultured cells, including an epithelial cell line relevant to the gastrointestinal tract. Finally, these particles were administered to mice by gavage, and their presence in various organs, including stomach, small intestine, cecum, colon, kidney, lung, brain, and spleen, was examined. By combining confocal fluorescence microscopy with inductively coupled plasma mass spectrometry, the presence of nanoparticles, rather than their dissolved form, was established in liver tissues.

Keywords: quantum dots, dyes, optical spectroscopy, NMR, zeta potential, mouse model, macrophages, Caco-2, nanoparticles in foods