Antibacterial Surface Functionalization On Porous Hydroxyapatite Scaffold

There was a high risk of infection induced by implantation in clinic,which might retard the recovery of the patients and even cause failure of implantation.To solve this problem,implants are functionalized for antibacterial application without any change of the properties in the matrix of scaffolds.Many efforts have been done on antibacterial functionalized surfaces.However,very few of them could be widely applied to the implants and the inhibition of delayed or recurrent infection induced by implants still remained challenging.Therefore,it is significant to design a sustainable anti-infected implant with high antibacterial efficiency.In the research,porous hydroxyapatite scaffolds(HA)was taken as a typical implant owning to their bone-like chemical property and nature porous structure.And two different bacteria killing strategies were applied to the implants,namely contact-killing and biocide-release.In the first part,quaternary ammonium polymers(PGDED-C6)was introduced to the surface of HA scaffold via surface initiated atom transfer radical polymerization(SI-ATRP),ring-opening reaction and quaternization.The modified scaffolds HA-PGDED-C6 showed significant damage to the bacteria adhered to the surface.However,the antibacterial ability of HA-PGDED-C6 scaffolds was highly relative to the amount of polymer brushes,and HA-PGDED-C6 scaffolds showed a certain degree of toxic towards preosteoblast in vitro.In pursuit of a solution to combat these disadvantages,we designed and fabricated a self-adaptive and sustained antibacterial implant by loading gentamicin sulfate(GS),a kind of aminoglycoside antibiotic in clinic practice,via SI-ATRP and Schiff-based reaction.The functionalized implant HA-GS could achieve an on-demanded releasing of GS with a"switching on-releasing-killing-switching off" process.HA-GS showed excellent antibacterial ability in both vitro and vivo.HA-GS further showed outstanding anti-infection in early stage of implantation and remarkable bone regeneration in the late stage by rabbit femur bone defected models.The present work provided a new concept for the therapy of bone defect with delayed and recurrent bacterial infection induced by the orthopedic implant.