Bioactive polymer grafting onto titanium alloy surfaces

Bioactive polymers bearing sulfonate (styrene sodium sulfonate, NaSS) and carboxylate (methylacrylic acid, MA) groups were grafted onto Ti6Al4V alloy surfaces by a two-step procedure. The Ti alloy surfaces were first chemically oxidized in a piranha solution and then directly subjected to radical po...

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Bibliographic Details
Published in:Acta biomaterialia 2010-02, Vol.6 (2), p.667-675
Main Authors: Michiardi, A., Hélary, G., Nguyen, P.-C.T., Gamble, L.J., Anagnostou, F., Castner, D.G., Migonney, V.
Format: Article
Language:English
Subjects:
Alloys
Animals
Bioactive polymers
Bones
Cell Adhesion
Cells, Cultured
Concentration (composition)
Grafting
Humans
Male
Mass Spectrometry
Microscopy, Atomic Force
Osteoblasts - cytology
Osteointegration
Polymers - chemistry
Rabbits
Spectrum Analysis - methods
Surgical implants
Titanium
Titanium alloy
Titanium base alloys
ToF-SIMS
X-ray photoelectron spectroscopy
X-Rays
XPS
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Summary:Bioactive polymers bearing sulfonate (styrene sodium sulfonate, NaSS) and carboxylate (methylacrylic acid, MA) groups were grafted onto Ti6Al4V alloy surfaces by a two-step procedure. The Ti alloy surfaces were first chemically oxidized in a piranha solution and then directly subjected to radical polymerization at 70 °C in the absence of oxygen. The grafted surfaces were characterized by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the toluidine blue colorimetric method. Toluidine blue results showed 1–5 μg cm −2 of polymer was grafted onto the oxidized Ti surfaces. Grafting resulted in a decrease in the XPS Ti and O signals from the underlying Ti substrate and a corresponding increase in the XPS C and S signals from the polymer layer. The ToF-SIMS intensities of the S − and SO − ions correlated linearly with the XPS atomic percent S concentrations and the ToF-SIMS intensity of the TiO 3H 2 − ion correlated linearly with the XPS atomic per cent Ti concentration. Thus, the ToF-SIMS S −, SO − and TiO 3H 2 − intensities can be used to quantify the composition and amount of grafted polymer. ToF-SIMS also detected ions that were more characteristic of the polymer molecular structure (C 6H 4SO 3 − and C 8H 7SO 3 − from NaSS, C 4H 5O 2 − from MA), but the intensity of these peaks depended on the polymer thickness and composition. An in vitro cell culture test was carried out with human osteoblast-like cells to assess the influence of the grafted polymers on cell response. Cell adhesion after 30 min of incubation showed significant differences between the grafted and ungrafted surfaces. The NaSS grafted surfaces showed the highest degree of cell adhesion while the MA-NaSS grafted surfaces showed the lowest degree of cell adhesion. After 4 weeks in vivo in rabbit femoral bones, bone was observed to be in direct contact with all implants. The percentage of mineralized tissue around the implants was similar for NaSS grafted and non-grafted implants (59% and 57%). The MA-NaSS grafted implant exhibited a lower amount of mineralized tissue (47%).
ISSN:1742-7061
1878-7568
DOI:10.1016/j.actbio.2009.08.043