Label-free characterization of live migrasome using quantitative phase imaging

Migrasomes, as organelles produced during cell migration, play important roles in physiological processes. Electron microscopy and fluorescence microscopy techniques have been used for studying the functions of microsomes, but they require invasive and complex experimental protocols, such as fixation, sectioning, and chemical labeling. To achieve noninvasive and label-free imaging of live migrasomes, we propose to apply a high sensitivity epi-mode quantitative phase microscopy (QPM) system and a silicon wafer-based cell culture platform to enhance the phase image contrast. Using this platform, the phase signal of sub-cellular structures can be optimized by adjusting the oxide layer thickness on the wafer. We cultured live L929 cells on silicon wafers of varying oxide layer thicknesses and imaged them using the QPM system. Our preliminary results showed that an optimum phase image contrast of the retraction fibers, connecting the cell bodies to migrasomes, can be obtained when the oxide layer thickness is around 186 nm. We also observed migrasome-like structures, but the phase imaging results need further validation.