Transfer three millimeters by 0.16 millimeters sapphire discs to a two-milliliter centrifuge tube containing one milliliter ethanol and sonicate it in an ultrasonic cleaner for 10 minutes. Burn each sapphire disc in an alcohol lamp flame until there are no visible deposits on the surface. Label one side of each sapphire disc with a number using a solvent-resistant pen.
Place the labeled sapphire discs on the bottom of a 35-millimeter culture dish with the labeled side facing up. Sterilize the cell culture dish with sapphire discs under ultraviolet light for 30 minutes. Flip the sapphire discs with tweezers, ensuring that the labeled side is facing down, and sterilize under ultraviolet light for an additional 30 minutes.
Seed the stable HeLa cell lines expressing MTn tags on the prepared sapphire discs and grow to 80 to 90%confluency in a cell incubator.
