3-[2-[2-[2-(2-Azidoethoxy)ethoxy]ethoxy]ethoxy]propanoic acid hydrazide

Azido-PEG4-hydrazide HCl salt is a PEG linker containing an azide group and a hydrazide group. The hydrophilic PEG spacer increases solubility of a compound in aqueous media. The azide group can react with alkyne, BCN, DBCO via Click Chemistry to yield a stable triazole linkage. The hydrazide group can react with an aldehyde to form a semi-permanent hydrozone bond.