Functionality-packed additively manufactured porous titanium implants. (June 2020)

• Record Type: Journal Article
• Authors: van Hengel, I.A.J.; Gelderman, F.S.A.; Athanasiadis, S.; Minneboo, M.; Weinans, H.; Fluit, A.C.; van der Eerden, B.C.J.; Fratila-Apachitei, L.E.; Apachitei, I.; Zadpoor, A.A.
• Is Part Of: Materials today bio. Volume 7(2020)
• Publication Date: 2020-06
• Subjects: Multifunctional surfaces -- Biofunctionalization -- Antimicrobial implant -- Additive manufacturing -- Strontium -- Silver nanoparticles; Materials science -- Periodicals; Biomedical engineering -- Periodicals; Biomedical materials -- Periodicals; 620.1
• DOI: 10.1016/j.mtbio.2020.100060
• Languages: English
• ISSNs: 2590-0064

Abstract

Abstract: The holy grail of orthopedic implant design is to ward off both aseptic and septic loosening for long enough that the implant outlives the patient. Questing this holy grail is feasible only if orthopedic biomaterials possess a long list of functionalities that enable them to discharge the onerous task of permanently replacing the native bone tissue. Here, we present a rationally designed and additive manufacturing (AM) topologically ordered porous metallic biomaterial that is made from Ti-6Al-4V using selective laser melting and packs most (if not all) of the required functionalities into a single implant. In addition to presenting a fully interconnected porous structure and form-freedom that enables realization of patient-specific implants, the biomaterials developed here were biofunctionalized using plasma electrolytic oxidation to locally release both osteogenic (i.e. strontium) and antibacterial (i.e. silver ions) agents. The same single-step biofunctionalization process also incorporated hydroxyapatite into the surface of the implants. Our measurements verified the continued release of both types of active agents up to 28 days. Assessment of the antibacterial activity in vitro and in an ex vivo murine model demonstrated extraordinarily high levels of bactericidal effects against a highly virulent and multidrug-resistant Staphylococcus aureus strain (i.e. USA300) with total eradication of both planktonic and adherent bacteria. This strong antibacterial behavior was combined with a significantly enhanced osteogenic behavior, as evidenced by significantly higher levels of alkaline phosphatase (ALP) activity compared with non-biofunctionalized implants. Finally, we discovered synergistic antibacterial behavior between strontium and silver ions, meaning that 4–32 folds lower concentrations of silver ions were required to achieve growth inhibition and total killing of bacteria. The functionality-packed biomaterial presented here demonstrates a unique combination of functionalities that make it an advanced prototype of future orthopedic biomaterials where implants will outlive patients. Graphical abstract: Image 1 Highlights: Rationally designed and selective laser melted porous titanium bone implants. Surface biofunctionalization by plasma electrolytic oxidation with strontium and silver nanoparticles. Biofunctionalized implants eradicated methicillin-resistant Staphylococcus aureus in vitro and ex vivo within 24 h. Novel synergistic antibacterial behavior between strontium and silver ions. Enhanced osteogenic differentiation of preosteoblastic cells after 11 days.