Photoinduced modification of the natural biopolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microfibrous surface...

A straightforward and versatile method for immobilizing polysaccharides on the surface of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) electrospun fibers is developed with the objective of designing a new functional biomaterial having a significant effect on cell proliferation. The approach relies on a one-step procedure: UV grafting of a photosensitive dextran (AQ-Dext) on the surface of PHBHV fibers according to a "grafting onto" method, with the use of an anthraquinone derivative. The photografting is conducted through a photoinduced free radical process employing an anthraquinone-based photosensitizer in aqueous medium. Under appropriate conditions, AQ-Dext reacts with C-H σ-bonds of the polymer substrate (PHBHV) to produce a semianthraquinone radical according to an H-abstraction reaction. This radical recombines together with the alkylradical (R˙) formed at the surface of PHBHV fibers via the oxygen atom of the anthraquinone photolinker. The photochemical mechanism of the AQ-Dext photolysis is entirely described for the first time by an electron spin resonance technique and laser flash photolysis. The modified PHBHV microfibrous scaffolds are extensively characterized by water contact angle measurements, XPS analysis and atomic force microscopy, confirming the covalent grafting of dextran on PHBHV fibers. Finally, a primary investigation demonstrates that dextran modified PHBHV fibers are permissive for optimized cell colonization and proliferation. The cell morphologies are described by SEM micrographs, revealing a significant affinity and favorable interactions for adherence of human mesenchymal stem cells (hMSCs) on scaffolds provided by dextran chemical structure. Moreover, the proliferation rate of hMSCs increases on this new functionalized biomaterial associated with a higher extra-cellular matrix production after 5 days of culture in comparison with native PHBHV fibers.