Acid-PEG25-Amide-Tri(3-methoxypropanamide-PEG10-Azide) Methane is a branched PEG linker containing one carboxylic acid and three terminal azide groups. The carboxylic acid can be coupled with primary amines to form stable amide bonds. The azide groups are available for click chemistry with alkynes, BCN, DBCO to form a stable triazole linkage. PEG spacers improve aqueous solubility and may alter DMPK properties.