Azido-PEG8-NHS ester is an 8 unit PEG linker with cleavable properties, commonly employed in the synthesis of antibody-drug conjugates (ADCs)[1]. This compound also serves as a PEG- and Alkyl/ether-based PROTAC linker, enabling its utilization in the synthesis of PROTACs[2].

ADCs are comprised of an antibody to which is attached an ADC cytotoxin through an ADC linker[1]. PROTACs contain two different ligands connected by a linker; one is a ligand for an E3 ubiquitin ligase and the other is for the target protein. PROTACs exploit the intracellular ubiquitin-proteasome system to selectively degrade target proteins[2].