Figure 6. A probable process that aggregated nanoparticles induce autophagic effect.

Aggregated nanoparticles enter into cells largely and are regarded as autophagic cargos. The as- formed endosomes initialize autophagy or fuse with autophagosomes to form amphisomes. Excess cargos saturate autophagy capacity and cause accumulation of amphisomes. The activity of lysosomes do not increase after fuse with amphisomes. The degradation of cargos in autolysosomes is slow due to the existence of highly stable nanoparticles; as a result, the number of amphisomes and autolysosomes increase dramatically inside cells. This figure was designed and drawn by Dengtong Huang.