Functionalized poly(glycerol sebacate)/poly(butylene succinate-dilinoleate) electrospun scaffolds for cardiac tissue engineering

摘要

Introduction: The blend of poly(glycerol sebacate)/poly(butylene succinate-dilinoleate) (PGS/PBS-DLA) has been already investigated for the fabrication of scaffolds for cardiac tissue engineering application, with promising results. Since its suitability in obtaining micro and nanofibrous mats resembling the native ECM structure, the electrospinning has been selected for the scaffolds fabrication. In this work a new copolymer (PBS-DLA) with 50wt.% of PBS segments has been investigated to improve the solution spinnability and scaffold mechanical properties. Functionalization of polymeric blend with collagen has been investigated with the aim to obtain suitable scaffolds for cardiac tissue engineering applications. Materials and Methods: The synthesis of PGS was carried out according to. PBS-DLA (50 wt.% of PBS segments) was synthesized according to. The electrospun mats have been obtained starting from a 35% w/v solution of PGS/PBS-DLA blend with 1:2 ratio in a mixture of dichloromethane/methanol (7:3). Also electrospun mats of neat PBS-DLA copolymer has been fabricated and used as control. For the electrospinning process the solution was fed with a flow rate of 1.8 ml/h, the applied voltage was 20kV and the distance needle-target was 15cm. Sample surface activation and functionalization have been performed by optimizing and adapting the protocols currently used for the functionalization of pure PBS and pure PGS films. Samples morphology was assessed by SEM analysis and surface activation and functionalization processes were assessed by using ATR-FTIR analysis, degradation and contact angle measurement. Sample mechanical characterization was performed by tensile test. Preliminary cell viability tests have been performed by using fibroblasts. Results and Discussion: SEM micrographs showed a homogeneous bead-free fibrous structure for both electrospun samples of the neat PBS-DLA copolymer and for the blend PGS/PBS-DLA. It is possible to notice also that the presence of PGS induces a surface modification on the fibers, as showed in figure 1, but it doesn't affect the average fiber diameter. Figure 1: SEM micrographs of electrospun pure PBS-DLA fibers (A) and blend PGS/PBS-DLA fibers (B). FTIR analysis confirms that the electrospinning process did not affect the polymer structure. FTIR analysis has been used also to assess the optimization of mats surface modification, activation and to confirm the presence of collagen. Regarding the contact angle measurements on PGS/PBS-DLA films and electrospun mats, the dispensed water drop was not stable, wetting completely and instantaneously the sample surface. This result demonstrates that the electrospinning process doesn't affect the sample hydrophilicity. Different behavior has been reported on pure PBS-DLA films and on crosslinked PGS films. Mechanical properties have been improved by using PBS-DLA 50:50 copolymer. Positive results from the preliminary cell viability tests have been obtained. Conclusions: Homogeneous electrospun microfibrous scaffold of PGS/PBS-DLA has been obtained. Results showed that these scaffolds could be suitable candidates for cardiac tissue engineering applications.