Bioactive polymer grafting onto titanium alloy surfaces

Citation

Michiardi, A.; Helary, G.; Nguyen, P. C. T.; Gamble, L. J.; Anagnostou, F.; Castner, D. G.; & Migonney, V. (2010). Bioactive polymer grafting onto titanium alloy surfaces. Acta biomaterialia, 6(2), 667-675.

Abstract

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 degrees 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 1-5microgcm(-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(3)H(2)(-) ion correlated linearly with the XPS atomic per cent Ti concentration. Thus, the ToF-SIMS S(-), SO(-) and TiO(3)H(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(6)H(4)SO(3)(-) and C(8)H(7)SO(3)(-) from NaSS, C(4)H(5)O(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 30min 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%).

Keyword(s)

Alloys
Animals
Cell Adhesion
Cells, Cultured
Humans
Male
Mass Spectrometry
Microscopy, Atomic Force
Osteoblasts
Polymers
Rabbits
Spectrum analysis
Titanium
X-Rays

Reference Type

Journal Article

Secondary Title

Acta biomaterialia

Author(s)

Michiardi, A.
Helary, G.
Nguyen, P. C. T.
Gamble, L. J.
Anagnostou, F.
Castner, D. G.
Migonney, V.

Year Published

2010

Volume Number

Issue Number

Pages

667-675

ISSN/ISBN

1878-7568

DOI

10.1016/j.actbio.2009.08.043