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