Synthesis and Self-Assembly of Degradable Peptide-Grafted PEG-Derivative Polymers

Polymer-peptide conjugates are promising materials that can be widely applied in drug delivery, tissue engineering, and antibacterial coatings. Grafting peptides to a degradable polymer backbone as side chains enhances the loading capability of peptides, facilitates the regulation of self-assembly, and imparts degradability to the resulting assemblies. In this study, a series of degradable polyethylene glycol (PEG) derivative polymers, denoted as P(PEG), featuring disulfide linkages and adamantyl groups, are prepared through Passerini polymerization and then functionalized with β-cyclodextrin (β-CD)-modified peptide octa-arginine (R8) and mPEG through molecular recognition, affording peptide-grafted PEG-derivative polymers. The self-assembly behaviors of the peptide-grafted polymers are influenced by the molecular weight of PEG prepolymers and the number of conjugated R8 and mPEG. Assemblies including micelle-like nanoparticles, polymersomes ranging from 160 to 270 nm, and polymersomes over 1 μm with low polydispersity can be obtained by controlling the structure of the peptide-grafted polymer. The presence of the disulfide bonds within the P(PEG) backbone facilitates the degradation of the assemblies into fragments under 10 nm in 10 mM glutathione solution. The assembly with an appropriate size and zeta potential could be applied as a nanocarrier for the delivery of the model drug doxorubicin (DOX) into 4T1 cells, leading to the apoptosis of the cancer cells.