N3-PEG5-aldehyde is a cleavable 5 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[1].
[1]. Beck A, et al. Strategies and challenges for the next generation of antibody-drug conjugates. Nat Rev Drug Discov. 2017 May;16(5):315-337.