The Internalization, Distribution, and Ultrastructure Damage of Silica Nanoparticles in Human Hepatic L-02 Cells

Nowadays, due to the wide use of amorphous silica nanoparticles (SiNPs), their adverse effects on human beings are attracting more attention. Understanding the interaction between SiNPs and cells is a fundamental step for toxicity assessment. Therefore, the current study is aimed at elaborating the internalization process, subcellular distribution, ultrastructure damage, and cytotoxicity of two different sizes of SiNPs (Nano-Si64 and Nano-Si46) in L-02 cells. The results indicate that the smaller-sized SiNPs, Nano-Si46, accumulate in cells more efficiently and produce a stronger cytotoxic effect than Nano-Si64. Both types of nanoparticles can accumulate in L-02 cells through the active endocytotic pathway and passive diffusion, and distribute within endocytotic vesicles or freely in cytoplasma and organelles. Microvillus fracture, membrane injury, mitochondria damage, degranulation of the rough endoplasmic reticulum, lamellar-like structure, lysosome destruction, autophagosomes, and autophagy-lysosomes are found in L-02 cells. Oxidative damage and direct interaction between SiNPs and subcellular structure are responsible for the toxicity.