Physico-chemical and biological analyzes of different scaffolds based on polyhydroxybutyrate and polyhydroxybutyrate-co-valerate

With the evolution in the development of biomaterials, the use of three-dimensional matrices (scaffolds), constructed from three-dimensional printing (3DP) via SLS (selective laser sinterization) and Filament Extrusion are gaining a lot of attention in the field of bone tissue engineering. The possibility to print 3D models based on previous virtual models with highly controlled shape, size and porosity, makes the material similar to the lost bone and favours the reconstruction of bone defects in the replacement of autografts considered "gold standard". The aim of this study was to physicochemically and biologically characterize Poly (3-hydroxybutyrate) (PHB) scaffolds, made by 3D printing via SLS coated with bacterial cellulose, functionalized or not with apatite (HA) and / or osteogenic growth peptide– (OGP) (Study 1) and matrices of Poly (hydroxybutyrate-co-valerate) (PHBV) and PHBV-La containing radiopaque apatite (PHBV-La20OAP) made by filament extrusion (Study 2) for bone regeneration. Results from physicochemical characterization by SEM/EDS demonstrated that the all produced scaffolds presented appropriate chemical composition and architecture (shape and porosity). The mechanical strength of the PHB scaffolds was not significantly affected my CB coating but was reduced after apatite addition. The La allowed an increase in the elasticity modulus of PHBV matrices. Experiments for analysis of the biological behaviour of the scaffolds showed that they allowed the maintenance of the viability, proliferation and similar cell spreading in all groups, with exception to the PHB(CB-HA)-OGP, which showed delayed cell proliferation during all periods. Mineral nodules were produced by cells on all scaffolds from both studies. Matrices from Study 2 allowed the expression of genes related to bone mineralization. Therefore, these results suggest that scaffolds evaluated in Studies 1 and 2 are promising for use in bone regeneration procedures. (AU)