Block copolymer of poly(ester amide) and polyesters: synthesis, characterization, and in vitro cellular response

In order to expand the properties and applications of aliphatic absorbable polyesters, a new biodegradable block copolymer family, poly(ester amide)-b-poly(ε-caprolactone) (PEA-b-PCL), was synthesized and characterized. These copolymers were synthesized by first preparing l-phenylalanine-based poly(ester amide) macroinitiators (Phe-PEAs) with free amine end groups via a solution polycondensation. The amine-terminated Phe-PEA macroinitiators were then used to initiate the ring-opening polymerization of ε-caprolactone monomer to prepare the PEA-b-PCL copolymers. The molecular weight (MW) of PEA-b-PCLs can be well controlled by adjusting the Phe-PEA MW and weight ratio of ε-caprolactone to Phe-PEA, and ranged from 7 to 50kgmol(-1). The copolymers' structure and properties were characterized by various physicochemical methods, such as nuclear magnetic resonance, gel permeation chromatography and solubility testing. The in vitro enzymatic biodegradation tests were performed to evaluate the biodegradation rate of the copolymers. The results showed that the introduction of Phe-PEA to PCL did not significantly change the degradation rate of PCL. Biological studies were conducted to assess the polymer's biological properties, like supporting the cell attachment and proliferation, and inflammation response. The results showed that the bovine aortic endothelial cells had very good attachment and proliferation performance on PEA-b-PCL coating surface. TNF-α release profiles showed that PEA-b-PCL exhibited a muted J774 macrophage inflammatory response.