Structural evolution and adhesion of titanium oxide film containing phosphorus and calcium on titanium by anodic oxidation

Rapid nano-scale surface modification on micro-arc oxidation coated titanium by microwave-assisted hydrothermal process

Nano to submicron scaled surface possesses excellent biological affinity and several processes have been undertaken to develop titanium implant with specific surface chemical and phase composition and nano-scale features. A simple process was used to modify the nano topographies on a micro-arc-oxidation (MAO) surface which shortens the time for the conventional hydrothermal process (HT). Nano-scaled anatase precipitates on the MAO surface with different crystallinities and morphologies were regulated via microwave-assisted hydrothermal in pure water (MWDD) or in pH conditioned mediums containing calcium and phosphorus ions (MWCP, MWCP9, MWCP11). The surface morphologies and structures were investigated by SEM, XRD, FTIR, and TEM. Anatase crystals as nano-spikes along [001] direction were observed on the surface of the MWDD and MWCP groups. Increasing the pH of the conditioned medium leads the precipitate to lose its crystallinity; the surface of MWCP11 is covered with amorphous anatase which has a 3D nano-sheet architecture. The MW treated surfaces possess superior hydrophilicity can adsorb more proteins (fibronectin and bovine serum albumin), and the osteoblasts-like MG63 cells on these surfaces have higher spreading ratios than on the MAO and HT groups. The cell viabilities in the MW groups were significantly higher than in the MAO and HT groups on the 7th day (P < 0.05), although their cell viabilities were similar on the first day. MWCP and MWCP11 have higher alkaline phosphatase activity on days 7 and 14 compared to other groups (P < 0.05). The MW treatment produces different nanomorphologies on the MAO surface and retains the original micro/submicron pores and surface calcium and phosphorus contents, thus it is expected to promote osseointegration without compromising the bond strength.

Modification of titanium alloys surface properties by plasma electrolytic oxidation (PEO) and influence on biological response

Surface characteristics can mediate biological interaction improving or affecting the tissue integration after implantation of a biomaterial. Features such as topography, wettability, surface energy and chemistry can be key determinants for interactions between cells and materials. Plasma electrolytic oxidation (PEO) is a technique used to control this kind of parameters by the addition of chemical species and the production of different morphologies on the surfaces of titanium and its alloys. With the purpose to improve the biological response, surfaces of c.p titanium and Ti6Al4V were modified by using PEO. Different electrolytes, voltages, current densities and anodizing times were tested in order to obtain surfaces with different characteristics. The obtained materials were characterized by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and glow discharge optical emission spectroscopy (GDOES). Wettability of the obtained surfaces were measured and the corresponding surface energies were calculated. Superhydrophilic surfaces with contact angles of about 0 degrees were obtained without any other treatment but PEO and this condition in some cases remains stable after several weeks of anodizing; crystal phase composition (anatase-rutile) of the anodic surface appears to be critical for obtaining this property. Finally, in order to verify the biological effect of these surfaces, osteoblast were seeded on the samples. It was found that cell behavior improves as SFE (surface free energy) and coating porosity increases whereas it is affected negatively by roughness. Techniques for surface modification allow changes in the coatings such as surface energy, roughness and porosity. As a consequence of this, biological response can be altered. In this paper, surfaces of c.p Ti and Ti6Al4V were modified by using plasma electrolytic oxidation (PEO) in order to accelerate the cell adhesion process.

Ultra-structural evaluation of an anodic oxidated titanium dental implant

Anodic oxidation is used for the surface treatment of commercial implants to improve their functional properties for clinical success. Here we conducted ultrastructural and chemical investigations into the micro- and nanostructure of the anodic oxide film of a titanium implant. The anodic oxidized layer of a Ti6Al4V alloy implant was examined ultrastructurally by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). They were also analyzed using energy dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The TEM revealed that the oxide layer of the Ti6Al4V implant prepared through anodic oxidation was separated into two layers. Al and V were not present on the top surface of the anodic oxide. This can be attributed to the biocompatibility of the anodic oxidized Ti6Al4V alloy implant, because the release of harmful metal ions such as Al and V can be suppressed by the biocompatibility.

In vitro antibacterial activity and cytocompatibility of bismuth doped micro-arc oxidized titanium

Chemical manipulations of the implant surface produce a bactericidal feature to prevent infections around dental implants. Despite the successful use of bismuth against mucosal and dermis infections, the antibacterial effect of bismuth in the oral cavity remains under investigation. The aim of this study was to evaluate the antibacterial activities of bismuth compounds against Actinobacillus actinomycetemcomitans, Staphylococcus mutans, and methicillin-resistant Staphylococcus aureus (MRSA), and to investigate the antimicrobial effects of bismuth doped micro-arc oxidation (MAO) titanium via an agar diffusion test. Cell viability, alkaline phosphatase activity, and mineralization level of MG63 osteoblast-like cells seeded on the coatings were evaluated at 1, 7, and 14 days. The results demonstrate that bismuth nitrate possess superior antibacterial activity when compared with bismuth acetate, bismuth subgallate, and silver nitrate. The bismuth doped MAO coating (contained 6.2 atomic percentage bismuth) had good biological affinities to the MG63 cells and showed a higher antibacterial efficacy against Actinobacillus actinomycetemcomitans and MRSA, where the reduction rates of colony numbers is higher than that of the control group by 1.5 and 1.9 times, respectively. These in vitro evaluations demonstrate that titanium implants with bismuth on the surface may be useful for better infection control.

Spectral and physical properties of electrochemically formed colored layers on titanium covered with clearcoats

We present the application and characterization of two commercial polymer clearcoats to electrochemically formed colored passive layers on titanium with the aim of providing physical protection required in many of titanium's applications, while allowing the unique appearance of the colored layers to show through. Thin layers of an acrylic automotive clearcoat (∼3.5 μm thick) and an epoxy marine clearcoat (∼6.5 μm thick) are applied to the colored titanium surfaces using spin coating, and are found to slightly modify their visual properties, while maintaining their bright, well-defined sparkling colors. Both clearcoats are found to significantly reduce the surface roughness, thereby reducing potential wear from friction and the adhesion of fine dirt particles. They are also found to notably decrease the wetting properties of colored titanium, furthering its protection against damage from ambient and aqueous media. The clearcoats show the ability to protect colored titanium from physical and chemical damage, with the automotive clearcoat exhibiting superior adhesion. Our electrochemical coloring technique combined with the application of clearcoats creates a new and unique system that does not rely solely on a polymer coating for its colorful appearance and protection against corrosion.

Structure, morphology and fibroblasts adhesion of surface-porous titanium via anodic oxidation

Surface-porous titanium samples were prepared by anodic oxidation in H(2)SO(4), H(3)PO(4) and CH(3)COOH electrolytes under various electrochemical conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were employed to characterize the structure, morphology and chemical composition of the surface layer, respectively. Closer analysis on the effect of the electrochemical conditions on pore configuration was involved. It can be indicated that porous titania was formed on the surface layer, and the pore configuration was influenced by electrolyte composition and crystal structure of the titania. The fibroblast cells experiment showed that anodic oxidation of titanium surface could promote fibroblast adhesion on Ti substrate. The results suggested that anodic oxidation of Ti in CH(3)COOH was suitable to obtain surface-porous titanium oxides layers, which might be beneficial for better soft tissue ingrowths.