A novel surface treatment for porous metallic implants that improves the rate of bony ongrowth.

Rapid implant fixation could prove beneficial in a host of clinical applications from total joint arthroplasty to trauma. We hypothesized that a novel self-assembled monolayer of phosphonate molecules (SAMP) covalently bonded to the oxide surface of titanium alloy would enhance bony integration. Beaded metallic rods were treated with one of three coatings: SAMP, SAMP + RGD peptide, or hydroxyapatite. Rods were inserted retrogradely into both distal femurs of 60 rabbits. Fifteen rabbits were sacrificed at 2, 4, 8, and 16 weeks. At each time, seven specimens for mechanical pull-out testing and three for histomorphometric analysis were available for each coating. At four weeks, both SAMP groups had significantly higher failure loads when compared to hydroxyapatite (p < 0.01). No significant differences were found among groups at other times, though the SAMP-alone group remained stronger at 16 weeks. Histology showed abundant new bone formation around all the three groups, though more enhanced formation was apparent in the two SAMP groups. With this novel treatment, with or without RGD, the failure load of implants doubled in half the time as compared with hydroxyapatite. Where early implant fixation is important, the SAMP treatment provides a simple, cost-effective enhancement to bony integration of orthopaedic implants.

Synthesis of Pt(dpk)Cl(4) and the reversible hydration to Pt(dpk-O-OH)Cl(3).H-phenCl: X-ray, spectroscopic, and electrochemical characterization.

We report on the synthesis of a platinum(IV) compound containing a di-2-pyridyl ketone (dpk) ligand that is stable both in its anhydrous form [Pt(dpk)Cl(4)] (1) and in its hydrated form [Pt(dpk-O-OH)Cl(3)].H-phenCl (2). The crystal structure of the hydrated form shows that one of the hydroxide groups from the resulting gem-diol has undergone a cyclometalation/condensation reaction resulting in an oxygen atom directly coordinated to the Pt(IV) center and the formation of H-phenCl. We correlate our physical data with predictions made by molecular modeling, and we propose an explanation for the unusual activity found for this dpk ketone. Spectroscopic and solubility studies are presented here, as well. Electrochemical studies of 1 indicate that it undergoes a highly irreversible reduction at a potential of about -0.45 V vs Ag(+)/Ag in CH(3)CN and that the irreversibility is likely due to an EC mechanism, the nature of which is currently under further investigation. Another distinct redox pair, apparently reversible, appears at a potential of about -1.1 V vs Ag(+)/Ag.