By anodization and thermal oxidation at 600 °C, an oxide layer on Ti with excellent corrosion resistance in strong acid solutions was prepared. The structural properties of TiO2 films before and after thermal oxidation were investigated with methods of Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XRD) and X-ray diffraction (XPS). The electrochemical characterization was recorded via electrochemical impedance spectroscopy, potentiodynamic polarization and Mott–Schottky methods. XRD results show that a duplex rutile/anatase structure formed after oxidation, and the amount of anatase phase increased as the treatment time was prolonged from 3 to 9 h. XPS analysis indicates that as the thermal oxidation time increased, more Ti vacancies were present in the titanium oxide films, with decreased donor concentration. Longer thermal oxidation promoted the formation of hydroxides of titanium on the surface, which is helpful to improve the passive ability of the film. The anodized and thermally oxidized Ti samples showed relatively high corrosion resistance in 4 M HCl and 4 M H2SO4 solutions at 100 ± 5 °C. The passive current density values of the thermally oxidized samples were five orders of magnitude under the testing condition compared with that of the anodized sample. With the oxidation time prolonged, the passive current density decreased further to some extent.
There is an urgent
need to develop biodegradable implants that
can degrade once they have fulfilled their function. Commercially
pure magnesium (Mg) and its alloys have the potential to surpass traditional
orthopedic implants due to their good biocompatibility and mechanical
properties, and most critically, biodegradability. The present work
focuses on the synthesis and characterization (microstructural, antibacterial,
surface, and biological properties) of poly(lactic-co-glycolic) acid (PLGA)/henna (Lawsonia inermis)/Cu-doped mesoporous bioactive glass nanoparticles (Cu-MBGNs) composite
coatings deposited via electrophoretic deposition (EPD) on Mg substrates.
PLGA/henna/Cu-MBGNs composite coatings were robustly deposited on
Mg substrates using EPD, and their adhesive strength, bioactivity,
antibacterial activity, corrosion resistance, and biodegradability
were thoroughly investigated. Scanning electron microscopy and Fourier
transform infrared spectroscopy studies confirmed the uniformity of
the coatings’ morphology and the presence of functional groups
that were attributable to PLGA, henna, and Cu-MBGNs, respectively.
The composites exhibited good hydrophilicity with an average roughness
of 2.6 μm, indicating desirable properties for bone forming
cell attachment, proliferation, and growth. Crosshatch and bend tests
confirmed that the adhesion of the coatings to Mg substrates and their
deformability were adequate. Electrochemical Tafel polarization tests
revealed that the composite coating adjusted the degradation rate
of Mg substrate in a human physiological environment. Incorporating
henna into PLGA/Cu-MBGNs composite coatings resulted in antibacterial
activity against Escherichia coli and Staphylococcus aureus. The coatings stimulated the
proliferation and growth of osteosarcoma MG-63 cells during the initial
incubation period of 48 h (determined by the WST-8 assay).
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