Surface characterization and antibacterial efficiency of well-ordered TiO2 nanotube surfaces fabricated on titanium foams.

Titanium (Ti)-based implants are not compatible enough due to their bio-inert character, insufficient antibacterial capabilities and stress-shielding problem for dental and orthopaedic implant applications. Thus, this work focused to fabricate, analyze and improve antibacterial properties titanium dioxide (TiO2) nanotube array surfaces on Ti foam by anodic oxidation (AO) process. The well-ordered nanotube arrays with approximately 75 nm were successfully fabricated at 40 V for 1 h on Ti foams. Ti and O were observed as major elements on AO-coated Ti foam surfaces. In addition, the existence of TiO2 structure was proved on AO-coated foam Ti surfaces. For potential dental and orthopedic implant application, in vitro antibacterial properties were investigated versus Staphylococcus aureus and Escherichia coli. For both bacteria, antibacterial properties of TiO2 nanotube surface were greater than bare Ti foam. The bacterial inhibition versus Staphylococcus aureus and Escherichia coli of TiO2 nanotube surfaces are improved as 53.3% and 69.4% compared to bare Ti foam.

Characterization and investigation of biological properties of silver nanoparticle-doped hydroxyapatite-based surfaces on zirconium.

The infections leading to failed implants can be controlled mainly by metal and metal oxide-based nanoparticles. In this work, the randomly distributed AgNPs-doped onto hydroxyapatite-based surfaces were produced on zirconium by micro arc oxidation (MAO) and electrochemical deposition processes. The surfaces were characterized by XRD, SEM, EDX mapping and EDX area and contact angle goniometer. AgNPs-doped MAO surfaces, which is beneficial for bone tissue growth exhibited hydrophilic behaviors. The bioactivity of the AgNPs-doped MAO surfaces is improved compared to bare Zr substrate under SBF conditions. Importantly, the AgNPs-doped MAO surfaces exhibited antimicrobial activity for E. coli and S. aureus compared to control samples.

Characterization and investigation of electrochemical and biological properties of antibacterial silver nanoparticle-deposited TiO2 nanotube array surfaces.

The one of main reasons of the premature failure of Ti-based implants is infections. The metal- and metal oxide-based nanoparticles have very high potential on controlling of infections. In this work, the randomly distributed AgNPs-deposited onto well-ordered TiO2 nanotube surfaces were fabricated on titanium by anodic oxidation (AO) and electrochemical deposition (ED) processes. AgNPs-deposited nanotube surfaces, which is beneficial for bone tissue growth exhibited hydrophilic behaviors. Moreover, the AgNPs-deposited nanotube surfaces, which prevent the leaching of metallic Ti ions from the implant surface, indicated great corrosion resistance under SBF conditions. The electrochemical corrosion resistance of AgNPs-deposited nanotube surfaces was improved up to about 145% compared to bare Gr2 surface. The cell viability of AgNPs-deposited nanotube surfaces was improved. Importantly, the AgNPs-deposited nanotube surfaces exhibited antibacterial activity for Gram-positive and Gram-negative bacteria. Eventually, it can be concluded that the AgNPs-deposited nanotube surfaces possess high stability for long-term usage of implant applications.

Surface characterization, electrochemical properties and in vitro biological properties of Zn-deposited TiO2 nanotube surfaces.

In this work, to improve antibacterial, biocompatible and bioactive properties of commercial pure titanium (cp-Ti) for implant applications, the Zn-deposited nanotube surfaces were fabricated on cp-Ti by using combined anodic oxidation (AO) and physical vapor deposition (PVD-TE) methods. Homogenous elemental distributions were observed through all surfaces. Moreover, Zn-deposited surfaces exhibited hydrophobic character while bare Ti surfaces were hydrophilic. Due to the biodegradable behavior of Zn on the nanotube surface, Zn-deposited nanotube surfaces showed higher corrosion current density than bare cp-Ti surface in SBF conditions as expected. In vitro biological properties such as cell viability, ALP activity, protein adsorption, hemolytic activity and antibacterial activity for Gram-positive and Gram-negative bacteria of all surfaces were investigated in detail. Cell viability, ALP activity and antibacterial properties of Zn-deposited nanotube surfaces were significantly improved with respect to bare cp-Ti. Moreover, hemolytic activity and protein adsorption of Zn-deposited nanotube surfaces were decreased. According to these results; a bioactive, biocompatible and antibacterial Zn-deposited nanotube surfaces produced on cp-Ti by using combined AO and PVD techniques can have potential for orthopedic and dental implant applications.

In vitro biological and antimicrobial properties of chitosan-based bioceramic coatings on zirconium.

Ca-based porous and rough bioceramic surfaces were coated onto zirconium by micro-arc oxidation (MAO). Subsequently, the MAO-coated zirconium surfaces were covered with an antimicrobial chitosan layer via the dip coating method to develop an antimicrobial, bioactive, and biocompatible composite biopolymer and bioceramic layer for implant applications. Cubic ZrO2, metastable Ca0.15Zr0.85O1.85, and Ca3(PO4)2 were detected on the MAO surface by powder-XRD. The existence of chitosan on the MAO-coated Zr surfaces was verified by FTIR. The micropores and thermal cracks on the bioceramic MAO surface were sealed using a chitosan coating, where the MAO surface was porous and rough. All elements such as Zr, O, Ca, P, and C were homogenously distributed across both surfaces. Moreover, both surfaces indicated hydrophobic properties. However, the contact angle of the MAO surface was lower than that of the chitosan-based MAO surface. In vitro bioactivity on both surfaces was investigated via XRD, SEM, and EDX analyses post-immersion in simulated body fluid (SBF) for 14 days. In vitro bioactivity was significantly enhanced on the chitosan-based MAO surface with respect to the MAO surface. In vitro microbial adhesions on the chitosan-based MAO surfaces were lower than the MAO surfaces for Staphylococcus aureus and Escherichia coli.

Bioactivity and biocompatibility of hydroxyapatite-based bioceramic coatings on zirconium by plasma electrolytic oxidation.

In the present work, hydroxyapatite (HAP)-based plasma electrolytic oxide (PEO) coatings were produced on zirconium at different current densities in a solution containing calcium acetate and ß-calcium glycerophosphate by a single step. The phase structure, surface morphology, functional groups, thickness and roughness of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), eddy current method and surface profilometer, respectively. The phases of cubic-zirconia, calcium zirconate and HAP were detected by XRD. The amount of HAP and calcium zirconate increased with increasing current density. The surface of the coatings was very porous and rough. Moreover, bioactivity and biocompatibility of the coatings were analyzed in vitro immersion simulated body fluid (SBF) and MTT (3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyl tetrazolium bromide) assay, hemolysis assay and bacterial formation. The apatite-forming ability of the coatings was evaluated after immersion in SBF up to 28days. After immersion, the bioactivity of HAP-based coatings on zirconium was greater than the ones of uncoated zirconium and zirconium oxide-based surface. The bioactivity of PEO surface on zirconium was significantly improved under SBF conditions. The bacterial adhesion of the coatings decreased with increasing current density. The bacterial adhesion of the coating produced at 0.370A/cm2 was minimum compared to uncoated zirconium coated at 0.260 and 0.292A/cm2. The hemocompatibility of HAP-based surfaces was improved by PEO. The cell attachment and proliferation of the PEO coatings were better than the one of uncoated zirconium according to MTT assay results.