Easily synthesized novel biodegradable copolyesters with adjustable properties for biomedical applications

Current compositions of biodegradable aliphatic polyesters experience a number of limitations associated with the difficulty of customizing mechanical, physicochemical, and biological properties for different biomedical applications. In this study, we propose a new class of multiblock copolyesters made using butylene succinate (BS) and triethylene succinate (TES). In particular, four copolyesters with the same chemical composition but different block lengths - P(BS18TES18), P(BS9TES9), P(BS4TES4), and P(BS2TES2) - were synthesized by reactive blending. Physicochemical characterization (DSC, WAXS, tensile tests, WCA, hydrolysis experiments) demonstrated that, by simply varying block length, it is possible to control polymer crystallinity, thermal and mechanical properties, wettability, and degradation rate. Copolymers displayed different stiffness, depending on the crystallinity degree, a tunable range of degradation rates, and different surface hydrophilicity. In vitro drug release and cell culture experiments were performed to evaluate the potential of these new copolyesters in the biomedical field. In particular, fluorescein isothiocyanate (FITC) was used as a model molecule to study the release profile of small molecules, and polymer cytocompatibility and fibronectin absorption capability were assessed. Depending on comonomer distribution, the polyesters are capable of releasing FITC in a tailorable manner. Moreover, the newly developed biomaterials are not cytotoxic and they are able to absorb proteins and, consequently, to tailor cell adhesion according to their surface hydrophilicity.