Heparin-conjugated PCL scaffolds fabricated by electrospinning and loaded with fibroblast growth factor 2

A biodegradable poly(ε-caprolactone) (PCL) was synthesized by ring-opening polymerization of ε-caprolactone catalyzed by Sn(Oct) ₂/BDO, followed by the heparin conjugation using EDC/NHS chemistry. The structure of the heparin-PCL conjugate was characterized by ¹H-NMR and GPC. The results of static contact angle and water uptake ratio measurements also confirmed the conjugation of heparin with the polyester. Its in vitro anticoagulation time was substantially extended, as evidenced by activated partial thromboplastin time (APTT) testing. Afterwards the conjugate was electrospun into small-diameter tubular scaffolds and loaded with Fibroblast Growth Factor 2 (FGF2) in aqueous solution. The loading efficiency was assayed by enzyme-linked immunosorbent assay (ELISA); the results indicated that the conjugate holds a higher loading efficiency than the blank polyester. The viability of released FGF2 was evaluated by MTT and cell adhesion tests. The amount and morphology of cells were significantly improved after FGF2 loading onto the electrospun heparin-PCL vascular scaffolds.