Hydroxyapatite-TiO2-SiO2-Coated 316L Stainless Steel for Biomedical Application

This study investigated the effectiveness of titania (TiO2) as a reinforcing phase in the hydroxyapatite (HAP) coating and silica (SiO2) single-layer as a bond coat between the TiO2-reinforced hydroxyapatite (TiO2/HAP) top layer and 316L stainless steel (316L SS) substrate on the corrosion resistance and mechanical properties of the underlying 316L SS metallic implant. Single-layer of SiO2 film was first deposited on 316L SS substrate and studied separately. Water contact angle measurements, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectrophotometer analysis were used to evaluate the hydroxyl group reactivity at the SiO2 outer surface. The microstructural and morphological results showed that the reinforcement of HAP coating with TiO2 and SiO2 reduced the crystallite size and the roughness surface. Indeed, the deposition of 50 vol. % TiO2-reinforced hydroxyapatite layer enhanced the hardness and the elastic modulus of the HAP coating, the introduction of SiO2 inner-layer on the surface of the 316L SS allowed the improvement of the bonding strength and the corrosion resistance as confirmed by scratch studies, nanoindentation and cyclic voltammetry tests

Electrochemical depositions of fluorohydroxyapatite doped by Cu2+, Zn2+, Ag+ on stainless steel substrates

International audienceFluoridated hydroxyapatite (FHA, Ca-10(PO4)(6)(OH)(2-x)F-x where 0 < x < 2 is the degree of fluoridation) and inorganic ions (Zn2+, Cu2+, Ag+) substituted fluoridated hydroxyapatite coatings (M-FHA) were deposited on the surface of medical grade 316L stainless steel samples by electrochemical deposition technique. The FHA coatings were co-substituted with antibacterial ions (Zn2+, Cu2+ or Ag+) by co-precipitation and ion-exchange methods. Characterization studies of coatings from X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) showed that the obtained layers are monophase crystals FHA and did not contain any discernible crystalline impurity. The particles of all samples are of nano size that gives thin layers. The surface morphology, microstructure and Ca/P atomic ratio of the FHA coatings can be regulated by varying electrolyte temperature. This later affects the porosity of the coating surface and the chemical compositions of the deposits. Quantitative elemental analysis indicates that the copper, zinc and silver ions are incorporated into the Fluorohydroxyapatite. The antimicrobial effects of doped fluorohydroxyapatite coatings against pathogen bacterial strains Staphylococcus aureus were tested in liquid media. The results are promising and demonstrated that all doped FHA samples exhibit excellent antimicrobial activity "in vitro" against the microorganism, so the antimicrobial properties of the coatings developed are improved

Electrochemical characterization of a mechanically stressed passive layer

The electrochemical behavior of the stainless steel 304L was studied under static mechanical stress. In a first approach, the elastic domain of the material was investigated by using the scanning electrochemical microscope (SECM). The Fe(CN)63− was used as mediator to characterize the electrochemical reactivity of the passive layer of SS 304L under various stress strengths. Keywords: Scanning electrochemical microscopy, Heterogeneous electron transfer, Stress corrosion, Passive laye

Biocompatibility of sol-gel hydroxyapatite-titania composite and bilayer coatings

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Resolution of (+)-abscisic acid using Arabidopsis glycosyltransferase

NRC publication: Ye

Morphological and Mechanical Properties of Hydroxyapatite Bilayer Coatings Deposited on 316L SS by Sol–Gel Method

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