Elastin-based side-chain polymers synthesized by ATRP

The synthesis of two monomers based on glutamic acid and the peptide VPGVG (V = valine, P = proline, and G = glycine), a commonly found sequence in tropoelastin, was investigated. The polymerizations of both monomers using atom transfer radical polymerization (ATRP) proceeded in a controlled manner and yielded polymers with narrow molecular weight distributions. The VPGVG sequence in the side chain of the polymer still maintained its characteristic LCST (lower critical solution temperature) behavior, according to CD spectroscopy. Triblock copolymers were prepared by polymerizing, using ATRP, the VPGVG monomer with a bifunctional poly(ethylene glycol) (PEG)-based initiator. This resulted in a material that upon heating in water clearly formed aggregates. These reversible aggregates were investigated using turbidity measurements and dynamic light scattering. A pH-dependent transition temperature of 40-70 degreesC was observed.