Although PEGylation
is widely used in biomedicine with great success,
it suffers from many drawbacks, such as polydispersity, nonbiodegradability,
and loss of precursor potency. Recently, the search for polyethylene
glycol (PEG) substitutes has attracted considerable attention. Some
of the substitutes partially address the drawbacks of PEGs, but sacrifice
the “stealth” effect of PEGs and bring in new issues.
Herein, we developed monodisperse oligoethylene glycol (M-OEG) polyamides
over 5000 Da as biodegradable and monodisperse PEGylation (M-PEGylation)
agents, which provided M-PEGylated peptides and proteins with high
monodispersity and a biodegradable PEG moiety. Compared to regular
PEGylated proteins with a complex “stealth” cloud of
PEG, the hydrogen bond interactions between the M-OEG polyamides and
proteins provided the M-PEGylated protein with a biodegradable “stealth”
cloak. The monodisperse and biodegradable M-PEGylation strategy as
well as the peculiar protein–M-OEG polyamide interactions may
shed light on many long-lasting issues during the development of PEGylated
biologic drugs, such as monodispersity, biodegradability, and tunable
conformation.