Preparing Hydrophilic Cell Observation Surface

The surface of the coverslip in a glass-bottom chamber was coated with carbon by vapor deposition using a vacuum evaporator (JEOL, JEE-400). The thickness of the carbon layer was approximately 20 nm. To make the surface hydrophilic, the surface of the carbon-coated coverslip was activated by plasma treatment. The chamber was sterilized with 70% ethanol and dried when necessary. The cells were settled on the surface of the carbon-coated coverslip and then slightly compressed using an agarose block (1.5%, dissolved in BSS, 1-mm thick) to observe the ventral cell surface^{33 (link)}. Under these conditions, the cells can migrate by extending pseudopods^{34 (link)}.