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Modification of electrospun nanofibrous poly(3-hydroxyalkanoate) (PHA)-based mats was implemented through two routes to obtain biomimetic scaffolds meant for tissue engineering applications. The first strategy relied on a physical functionalization of scaffolds thanks to an original route which combined both electrospinning and electrospraying, while the second approach implied the chemical modification of fiber surface via the introduction of reactive functional groups to further conjugate bioactive molecules. The degree of glycidyl methacrylate grafting on PHA reached 20% after 300s under photoactivation. Epoxy groups were modified via the attachment of a peptide sequence, such as Arg-Gly-Asp (RGD), to obtain biofunctionalized scaffolds. SEM and TEM analysis of mats showed uniform and well-oriented beadless fibers. The electrospinning/electrospraying tandem process afforded highly porous scaffolds characterized by a porosity ratio up to 83% and fibers with a surface largely covered by the electrosprayed bioceramic, i.e. hydroxyapatite. Gelatin was added to the latter PHA-based scaffolds to improve the hydrophilicity of the scaffolds (water contact angle about 0°) as well as their biological properties, in particular cell adhesion, proliferation, and osteogenic differentiation after 5days of human mesenchymal stromal culture. Human mesenchymal stromal cells exhibited a better adhesion and proliferation on the biofunctionalized scaffolds than that on non-functionalized PHA mats.

International audience; Original in situ measurements of volume variation and small angle light scattering (SALS) are performed on silica filled Styrene Butadiene Rubber (SBR) during tensile tests. The influence of the silica treatment on the mechanisms involved is explored with sample carefully characterised and with the same filler dispersion. Two different types of silane are used as treatment, an alkoxy silane (so called covering agent) and a coupling agent which enables covalent bonds between the silica and the polymer matrix. It is shown that the coupling agent delays void formation in the samples and leads at intermediary strain to the reorganisation of the filler structure while the covering agent eases the void formation which also occurs without silica surface treatment.