In situ exploration of characteristics of macropinocytosis and size range of internalized substances in cells by 3D-structured illumination microscopy

Jing Jin,1 Yanting Shen,2 Biao Zhang,1 Rong Deng,3 Dianshuai Huang,1 Tianqi Lu,1 Fei Sun,1,* Shuping Xu,2,* Chongyang Liang1,*1Institute of Frontier Medical Science, Jilin University, Changchun 130021, Jilin, People’s Republic of China; 2State Key Lab of Supramolecular Structure and Materials, Jilin University, Changchun 130021, Jilin, People’s Republic of China; 3International Joint Research Laboratory of Nano-Micro Architecture Chemistry (NMAC), Jilin University, Changchun 130021, Jilin, People’s Republic of China*These authors contributed equally to this workBackground: Macropinocytosis can occur in various types of cells and displays multiple functions. However, real-time observation and characterization of the structures of macropinocytosis on the surface of the cell membrane is not yet possible.Materials and methods: Here, we establish a real-time live cell surface imaging method using three-dimensional-structured illumination microscopy. Based on this, observation of the dynamic macropinocytosis process and morphological data of internalized structures on the surface of pancreatic cancer cells were achieved during macropinocytosis. Next, different-sized silica nanoparticles (SiO2 NPs) were used as the scale for identifying the size range of internalized substances of macropinocytosis in pancreatic cancer cells.Results and conclusion: Our study not only provides a practical method and more structural data for further investigation of macropinocytosis, but also makes deeper understanding of the cell response toward nanomaterials as well as nanodrugs possible.Keywords: nanomaterials, macropinocytosis, 3D-SIM, internalizatio