Hydroxy-PEG3-SS-PEG3-alcohol is also a cleavable 6 unit PEG ADC linker used in the synthesis of antibody-drug conjugates (ADCs)[1].
ADCs are comprised of an antibody to which is attached an ADC cytotoxin through an ADC linker[2].
[1]. Barrientos AG, et al. Gold glyconanoparticles: synthetic polyvalent ligands mimicking glycocalyx-like surfaces as tools for glycobiological studies. Chemistry. 2003 May 9;9(9):1909-21.