Thin Solid Films, Vol.516, No.18, 6277-6286, 2008
Enhanced bonding of chitosan to implant quality titanium via four treatment combinations
Bioactive coatings have been investigated to enhance the integration of orthopaedic and dental-craniofacial implants in the surrounding bone tissue. Chitosan has been shown to possess many properties desirable in implant coatings, such as cell attachment and growth, and encouraging ordered bone tissue formation. Previous studies have produced methods to deposit chitosan onto a titanium surface using both two-step and three-step reaction schemes. In the current study, two different titanium surface treatments were evaluated for determining the strength of chitosan coatings bonded to titanium via two reaction processes. The chitosan coatings produced from the four treatment combinations were examined using X-ray Photoelectron Spectroscopy, which demonstrated that the final coatings were similar in composition to the previously reported coatings. Coatings examined by nano-indentation, exhibited hardness (0.19 +/- 0.08 GPa) and elastic modulus (4.90 +/- 1.82 GPa) values similar to the hardness and elastic modulus values previously reported. Scanning Electron Microscopy examination of the nano-indentation marks revealed cracks only at sites of applied stress, demonstrating that the chitosan coatings were able to absorb the applied stress. Bulk adhesion of the chitosan coatings demonstrated significant increases in bond strength (19.50 +/- 1.63 MPa) over previously reported data (1.5-1.8 MPa), but no significant differences were seen between the four treatment combinations. Contact angle testing demonstrated that the chitosan coatings were more hydrophobic (98.0 +/- 3.6 degrees) than published values (76.4 +/- 5.1 degrees). Overall, mechanical testing demonstrated that, while the bulk properties of the chitosan coating were unaffected by the four treatment combinations, the bulk adhesion of the chitosan coating was greatly increased and high quality coatings were produced. (c) 2007 Elsevier B.V. All rights reserved.