In vivo evaluation of modified titanium implant surfaces produced using a hybrid plasma spraying processing

Monitoring of titanium base alloys–biofluids interface

Monitoring of the titanium, Ti-5Al-4V, Ti-6Al-4Fe implant materials--Ringer 1 and Ringer 2 solutions (of different pH values) interface for long term was studied in this work. In Ringer 1 solution (with high chloride ion content) all biomaterials present self-passivation. On Ti-6Al-4Fe alloy, the breakdown of the passive film was registered but at high pitting potential; pitting protection potential is very noble and can not be reached in human fluids. In Ringer 2 solution was obtained more electropositive corrosion potential values than in Ringer 1 solution; pitting corrosion of Ti-6Al-4Fe alloy is characterised by nobler breakdown and pitting protection potential values, therefore a better pitting corrosion resistance and tendency. Ion release increases in time, for the first 400-600 immersion hours and then tend to a constant level with very low values, non-dangerous for human body. All open circuit potentials oscillate around some electropositive values. The potential gradients calculated for extreme pH values have low values during 20,000 exposure hours and can not accelerate the corrosion. Atomic Force Microscopy images obtained after different exposure periods in Ringer 1 solution revealed that the roughness increased in time, suggesting a dynamic process at biomaterial-biofluid interface. X-ray Photoelectron spectra obtained after 2880 immersion hours in Ringer 2 solution show the existence of protective titanium dioxide TiO(2) and TiO and Ti(2)O(3) oxides both for titanium and Ti-5Al-4V alloy. Also, Al(2)O(3) oxide was detected.

A Study of Hydroxyapatite Coating on Porous Ti Compact by Electrostatic Spray Deposition

Coatings of hydroxyapatite (HA) on the porous-surfaced Ti compact have been conducted by electrostatic spray deposition (EDS). The precursor solution for the HA coating by ESD was prepared by mixing nano-scaled HA powder with ethyl alcohol. As-deposited HA films on the substrate were heat-treated (400 ~ 900 °C) and their physical characteristics were investigated by Scanning Electronic Microscopy (SEM), X-ray Diffractometer (XRD), and X-ray Photoelectronic Spectroscopy (XPS). As-deposited HA films were consisted of HA particles which were uniformly distributed on the Ti substrate, showing a porous structure. By heat treatment, HA particles were agglomerated each other and melted to form a highly dense and homogeneous coating layer consisted of equiaxed nano-scaled grains. HA coatings on the porous-surfaced Ti compact consisted of highly crystalline apatite phase with the Ca/P ratio of about 1.67 were successfully obtained by using ESD.

Determination of daunomycin at a novel COOH/indium tin oxide ion implantation-modified electrode

A novel COOH+ ion implantation-modified indium tin oxide (COOH/ITO) electrode was prepared for the first time and applied for determination of daunomycin (or daunorubicin [DNR]). The electrode showed higher catalytic activity than bare ITO electrode with good reproducibility and stability. The determination condition of linear voltammetry was optimized. A calibration curve was obtained over the range 2.0 x 10(-7) to 5.0 x 10(-6)mol/L, with a correlation coefficient of 0.9909 and a limit of detection of 1.0 x 10(-7)mol/L. The selectivity of the electrode was illustrated by determination of DNR in samples prepared of urine. X-ray photoelectron spectroscopy (XPS) analysis results showed that the implanted COOH+ maintained characteristics of organic group -COOH. A field emission-scanning electron microscope (FSEM) result showed that the implanted surface caused defects and partial dislocations and formed many active centers.