Hydroxyapatite coated with chitosan and functionalized with polyphenols

This thesis is performed in the contex of Nat4more project in collaboration with the Innovation Center of Island. In Island it was studied the behavior of chitosan DD50 film on hydroxyapatite, SCNA bioglass and titanium substrate before and after packaging, sterilization and 6 month storages. It was done Raman, SEM, microscope analysis of the samples and also UV analysis before and after incubation 24h, 3d and 7d at 37°C in distilled water. This is done to see the chitosan release in each substrates and the impact of packaging, sterilization and storage on chitosan coating. In adddition it is performed different chitosan coating on Ti and HA substrate with chitosan 50DD and 70DD, also with TPP crosslinking 15%w/v. To see the different behavior of chitosan and TPP crosslinking on Ti samples are performed swelling and dissolution analysis by using Ch50DD and CH70DD with TPP crosslinking at 5, 15 and 30%w/v. Then at Polito it is worked with HA samples with chitosan 50DD and crosslinked with 15%TPP (HA_CH50-15), these samples are functionalizated with polyphenols of red grapes. It is studied the release of polyphenols at 37°C in PBS pH7.4 solution and a solution that simulates the inflammation with H2O2 pH4.9. FTIR, UV-vis, Folin, DPPH and fluo images are performed on the samples HA_CH50-15 before and after the release of polyphenols. In addition zeta potential of HA__CH50-15 with and without polyphenols and HA_CH50 are performed. The results shows that the polyphenols and chitosan coating remain after the incubation of PBS and H2O2 solution, the polyphenols are released in higher quantity in H2O2 solution, so this is good to limit the inflammation and to scavenge radicals thank to the polyphenols. Indeed this scaffold should help bone's healing, because HA supply with a good substrate for bone regeneration and osseointegration, the chitosan is a good antibacterial biomaterial that should avoid the infection and bacteria growth, and finally the polyphenols thank to the ability to scavenge free radicals should avoid and limit an excessive inflammation. So a partial release of polyphenols in inflammation condition is a good results for the bone healing.