A sterile solution intended to be injected via an endoscopic injection needle into the submucosal layer of the gastrointestinal tract to facilitate excision of mucosal lesions (e.g., polyps, adenomas, early cancers) by lifting the mucosa over a bubble of fluid. It is typically a gel-like emulsion (e.g., containing fats and/or salts), and may include a dye. This is a single-use device.