Degradation of hollow mesoporous silica nanoparticles in human umbilical vein endothelial cells.

Hollow mesoporous silica nanoparticles (HMSNs) are considered a potential drug delivery system owing to their recognized advantages in drug loading and releasing. However, whether HMSN could be degraded inside the cells remains unknown. In this study, based on the observations by transmission electron microscopy, fluorescence staining, enzymatic proteolysis, and inductively coupled plasma atomic emission spectroscopy, HMSNs were proved to be degradable in human umbilical vein endothelial cells. The degradation first took place in cytoplasm and lysosomes, and secondly in lysosomes only. The Si content in culture medium increased as the time increases, suggesting that the degradation product inside the cells could be excreted into the culture medium. The degrading rate is fast in the first 2 days and slow after 2 days. The present results provided a clue to further research on the metabolic way and cytotoxicity of silica nanoparticles.