Peptide-guided self-assembly of polyethylene glycol-b-poly(ε-caprolactone-g-peptide) block copolymers

Abstract

Biodegradable poly(ethylene glycol)-b-poly(ε-caprolactone-g-peptide) (PEG-b-PCL-g-peptide) copolymers were synthesized using a combination of ring opening polymerization and thiol-yne photoaddition of peptides on the alkyne functional PCL block. The peptides Phe-Phe, Tyr-Tyr and Arg-Gly-Asp were selected based on the expected interactions (Pi-stacking, H-bonding, electrostatic). The self-assembly of these copolymers was studied via testing the effect of various parameters such as the nature of the solvent and non-solvant as well as their ratio, mixing method, temperature and concentration. Structures obtained by varying these parameters were characterised using transmission electron microscopy (TEM) and dynamic light scattering (DLS). Spherical and lamellar structures (oval leaf-shaped) of different sizes were identified as a function of the conditions. The role of the crystallisation and of the peptides was highlighted with more defined and stable structures obtained for Tyr-Tyr functional copolymers.