Transmission electron microscopy and flow cytometry study of cellular uptake of unmodified Pr³⁺:LaF<inf>3</inf> nanoparticles in dynamic

Abstract

The article represents the transmission electron microscopy (TEM) and flow cytometry study of A-549 (human lung carcinoma) cellular uptake of unmodified Pr3+:LaF3 nanoplates and nanospheres after 2, 10, and 24 h of nanoparticles exposure. The studied Pr3+:LaF3 (CPr = 1 mol.%) nanoplates (length = 64.0 ± 1.0 nm) and nanospheres (diameter = 13.0 0.4 nm) are hexagonal structured nanocrystals without amorphous phase. Both morphotypes of nanoparticles (nanoplates and nanospheres) are easily internalized by A-549 cells via macropinocytosis after 2, 10, and 24 h of nanoparticle exposure. The nanoparticles were not observed in cell nuclei and other organelles. During macropinocytosis, relatively large vesicles (0.2–5 μm) are formed. The flow cytometry experiments revealed that the internalized nanoparticles increase the cells’ optical inhomogeneous that leads to an increase of side scattered light intensity by ~ 10% without any dynamic during 24 h (for both morphotypes of nanoparticles). Probably, it can be explained by the fact that macropinocytosis is a dynamic process and some macropinosomes appear and move in the cytoplasm, in turn, other macropinosomes travel back to the cell surface of the membrane and release the content to the extracellular space, consequently, the equilibrium is achieved.