Development of a facile fluorophosphonate-functionalised titanium surface for potential orthopaedic applications

Abstract

s Background Aseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £137 m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices. Methods In realising the development of a superior titanium technology, we exploited the natural affinity of titanium for phosphonic acids and developed a facile means of coating the metal with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation. Results Herein, we provide evidence that simply immersing titanium in aqueous solutions of FHBP afforded a surface that was superior to unmodified metal at enhancing osteoblast maturation. Importantly, FHBP-functionalised titanium remained stable to 2 years of ambient storage, resisted ∼35 kGy of gamma irradiation and survived implantation into a bone substitute (Sawbone™) and irrigation. Conclusion The facile step we have taken to modify titanium and the robustness of the final surface finish are appealing properties that are likely to attract the attention of implant manufacturers in the future. The translational potential of this article We have generated a functionalised titanium (Ti) surface by simply immersing Ti in aqueous solutions of a bioactive lipid. As a facile procedure it will have greater appeal to implant manufacturers compared to onerous and costly developmental processes.

Polydopamine-Lysophosphatidate-Functionalised Titanium: A Novel Hybrid Surface Finish for Bone Regenerative Applications

“…The agent in question is (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), which we discovered synergistically co-operated with calcitriol (1,25D) to bolster human osteoblast maturation [8]. In a biomaterials context, this bioactive lipid is particularly attractive given its small size and stability; in contrast to much larger, bulkier, protein growth factors, e.g., BMP-2, we find FHBP-coated Ti could withstand autoclaving [7] and 35kGy gamma irradiation [9]. It is also likely, given its structural similarity to related lipids (e.g., oleic acid), that FHBP will withstand prolonged ambient storage (potentially 2-3 years), as would be expected for routinely stored implantable devices.…”

“…It is also likely, given its structural similarity to related lipids (e.g., oleic acid), that FHBP will withstand prolonged ambient storage (potentially 2-3 years), as would be expected for routinely stored implantable devices. Credence is given to this possibility in light of our recent study, wherein FHBP-coated Ti retained the ability to enhance 1,25D-induced osteoblast maturation after 24 months of ambient storage in air [9].…”