In a study published in Nano Letters, Lawrence Livermore National Laboratory (LLNL)'s Mike Malfatti, Heather Palko, Ed Kuhn, and Ken Turteltaub report on accelerator mass spectrometry measurements used to investigate the relationship between administered dose, pharmacokinetics (PK), and long-term biodistribution of carbon 14-labeled silica nanopartocles in vivo.
The increasing use of nanoparticles (NPs) for a wide variety of commercial, industrial, and biomedical application has led to safety concerns. Because of their unique properties such as monodispersity, large surface area, and high drug loading efficiency, silica nanoparticles (SiNPs) have been developed for a vast array of biomedical uses such as optical imaging, cancer therapy, targeted drug delivery, and controlled drug release for genes and proteins. Silica nanoparticles also are found in many personal care products and in certain foods.
However, as the potential uses of SiNPs have increased, research looking into the biological fate and toxicity has not kept up to speed. Studies have shown that inhalation of microcrystalline silica may be linked with the pulmonary disease silicosis in humans. Chronic inhalation studies in rats have been associated with pulmonary fibrosis and cancer, and exposure to microscale amporphous silica has been linked to inflammation, granuloma formation, and emphysema. A complete understanding of the size, shape, and composition-dependent interactions of SiNPs with biological systems is lacking, largely due to suitable analytical methods.
The Livermore PK analysis showed that SiNPs were rapidly cleared from the circulatory system (the "central compartment" in PK models) and were distributed to various body tissues, where they persisted over the eight-week time course of the study, raising questions about the potential for bioaccumulation and associated long-term effects.