PEG Linkers

PEG linkers provide covalent spacing and hydrophilicity in drug conjugates, rather than receptor-level agonism or inhibition^[1]. Mechanistically, PEGylation links one or more polyethylene glycol chains to protein, peptide, or non-peptide molecules and improves delivery-relevant physicochemical behavior^[1]. Releasable PEGylation uses customized linkers that reversibly tether therapeutic moieties to polyethylene glycol polymers, enabling regeneration of authentic and fully active drug^[2]. In antibody-drug conjugates, hydrophilic PEG-containing linkers mask or reduce payload hydrophobicity and improve physical stability and in vivo performance^[3]. Disease-model studies in cancer ADC research show that hydrophilic linker design supports antibody-maytansinoid conjugates and PEGylated glucuronide-MMAE conjugates^[4][5]. Compared with alkyl linkers in PROTACs, ethylene glycol linkers can reduce cell permeability, showing that linker polarity and folding must be optimized for intracellular degrader design^[6]. Compared with other hydrophilic linker classes, PEG linkers act as monodisperse hydrophilicity reservoirs for highly loaded lysine-conjugated ADCs^[3]. For experimental applications, PEG linker selection should prioritize spacer length, cleavable release chemistry, hydrophilicity, aggregation control, and payload exposure in ADC, PEGylation, and PROTAC projects^[2][3][6][7].