title: Chemical nature of implant-derived titanium(IV) ions in synovial fluid.
abstract: Previous investigations have indicated a deleterious leakage of Ti(III) and/or Ti(IV) species from Ti-Al-V alloy joint prostheses into adjacent tissue, synovium or synovial fluid (SF) in vivo. In view of the importance of the particular chemical nature of such complexes in determining their biological activity, we have employed high field proton (1H) NMR spectroscopy to "speciate" Ti(IV) in inflammatory SF. Treatment of osteoarthritic SF samples with increasing concentrations of Ti(IV) (0.10-1.03 mM [TiO(C2O4)2]2-) gave rise to a specific broadening of the citrate proton resonances, indicating that this bioavailable oxygen-donor ligand plays an important role in complexing implant-derived Ti(IV). 1H NMR analysis of Ti(IV)-loaded SF samples subsequently treated with a large excess of ascorbate (0.05 M) showed that this added Ti(IV) chelator was only poorly effective in removing this metal ion from Ti(IV)-citrate/Ti(IV)-oxycitrate complexes. The results obtained here provide evidence for complexation of the low-molecular-mass (non-protein-bound) fraction of implant-derived Ti(IV) by citrate in vivo.
authors.affiliation: Department of Applied Science, Faculty of Engineering, Science and the Built Environment, London South Bank University, 103 Borough Road, London SE1 0AA, UK.
authors.forename: Christopher J L
authors.initials: CJ
authors.lastname: Silwood
authors.forename: Martin
authors.initials: M
authors.lastname: Grootveld
mesh_terms: D019643:Arthroplasty, Replacement / Q000009:adverse effects*; D006801:Humans; D007477:Ions / Q000737:chemistry*; D007595:Joint Prosthesis / Q000009:adverse effects*; D009682:Magnetic Resonance Spectroscopy; D008875:Middle Aged; D013582:Synovial Fluid / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D007477:Ions; D014025:Titanium