Cellular Uptake, Cytotoxicity and Trafficking of Supported Lipid-Bilayer-Coated Lanthanide Upconverting Nanoparticles in Alveolar Lung Cancer Cells

An understanding of the cellular uptake and trafficking of nanoparticles is important for the design of efficient nanoparticle-based nanomedicines. Herein we compare the uptake and cytotoxicity of diamond-shape, lanthanide upconverting nanoparticles (LiYF4:Tm3+/Yb3+ UCNPs) with different surface properties. Coating the UCNP with a supported lipid bilayer yielded negligible cytotoxicity on A549 human lung cancer cells, albeit with a lower, but still significant, UCNP uptake compared to oleate-capped and oleate-free UCNPs. Using inhibition studies and cellular imaging we demonstrate that the UCNPs are internalized by endocytosis and energy independent pathways and trafficked to the endoplasmic reticulum, Golgi apparatus, and lamellar and lipid bodies. Upon incorporation of a photostimulus within the bilayer coating, release of a Nile red as a hydrophobic drug model was demonstrated.