O-(2-AZIDOETHYL)-O-(2-(DIGLYCOLYL-AMINO)ETHYL)EG-7

2-((Azido-PEG8-carbamoyl)methoxy)acetic acid is a PEG linker containing an azide group with a terminal carboxylic acid. The hydrophilic PEG spacer increases solubility in aqueous media. The azide group can react with alkyne, BCN, DBCO via Click Chemistry to yield a stable triazole linkage. The terminal carboxylic acid can react with primary amine groups in the presence of activators (e.g. EDC, or HATU) to form a stable amide bond.