Enabling Technologies
(Track)
Superhydrophobic quasi periodic self-organized structures fabricated on titanium surfaces
EP Ivanova
Faculty of Life and Social Sciences
Swinburne University of Technology
Australia
Abstract:
Titanium and its alloys have been widely used in biomedical implants, including orthopaedic, dental prostheses, cardiac valves, and in the microsurgical restoration of middle ear function. The performance of medical implants can be negatively influenced by the presence of bacterial infection. Currently, biofilm formation by human pathogenic bacteria on medical implants is one of most common causes of device failure, often resulting in the necessity to surgically remove the implant.
The design of bacterial antifouling surfaces by surface structuring is one attractive solution for the prevention of bacterial adhesion and the subsequent formation of a biofilm. We have designed and optimized the femtosecond laser processing parameters to allow the generation of two tier micro- and nanoscale quasi periodic self-organized surface structures similar to naturally occurring hierarchical structure with superhydrophobic features found on the surface of the lotus leaf Nelumbo nucifera. The fabrication of a convex microstructure covered with nano-sized features was found to be possible using significantly higher laser fluences of 20 - 100 J/cm². To avoid ripple formation and to manufacture anisotropic nanoroughness, circular polarized light was used. The grains formed on the titanium surfaces appeared to be with a size ranging between 10 µm and 20 µm possessing 200 nm (or less) wide irregular undulations. The biomimetic surface structuring transformed initially hydrophilic titanium surfaces with water contact angle of θW 73° ± 3° into superhydrophobic surfaces with a water contact angle θW of 166° ± 4°. Investigations of S. aureus and P. aeruginosa interactions with superhydrophobic surfaces at the surface-liquid interface revealed a highly selective adhesion pattern for two pathogenic bacteria. It was found that while S. aureus cells were able to successfully colonise the superhydrophobic titanium surfaces, the attachment of the P. aeruginosa cells was vastly reduced, with the adhered cell numbers being found to be below the estimated lower detection limit.
