Propargyl-PEG-silane is a silane-based cross-linking agent used to covalently link various surfaces, including glass, metals, and polymers. It is a compound that contains both propargyl and polyethylene glycol (PEG) groups. The propargyl group is a reactive, three-carbon alkyne group that can be used to form covalent bonds with other molecules. The PEG group is a polymeric hydrophilic group that can be used to increase the water solubility of the compound. Propargyl-PEG-silane is a versatile cross-linking agent that is often used in bioconjugation and surface modification applications.