This work aims to describe the effect of the surface modification of TiO2 nanotube (TNT) layers on Ti-6Al-4V (TiAlV) alloy by ultrathin TiO2 coatings prepared via Atomic Layer Deposition (ALD) on the growth of MG-63 osteoblastic cells. The TNT layers with two distinctly different inner diameters, namely ∼15 nm and ∼50 nm, were prepared via anodic oxidation of the TiAlV alloy. Flat, i.e., non-anodized, TiAlV alloy foils were used as reference substrates. Additionally, a part of the TNT layers and alloy foils was coated with ultrathin coatings of TiO2 by ALD. The number of TiO2 ALD cycles used was 1 and 5 leading to a nominal TiO2 thickness of ∼0.055 and ∼0.3 nm, respectively. The ultrathin TiO2 coating by ALD enabled to optimize the surface hydrophilicity for optimal cell growth. In addition, coatings shaded impurities of V- and F-based species (stemming from the alloy and the anodization electrolyte) that affect the biocompatibility of the tested materials while preserving the original structure and morphology. The evaluation of the biocompatibility before and after TiO2 ALD coating on TiAlV flat surfaces and TNT layers was carried out using MG-63 osteoblastic cells and compared after incubation for up to 96 h. The cell growth, adhesion, and proliferation of the MG-63 on TiAlV foils and TNT layers showed significant enhancement after the surface modification by TiO2 ALD.

• Klíčová slova
• MG-63 cells, Ti-6Al-4V alloy, TiO2 nanotube layers, atomic layer deposition, cell growth, cell proliferation,
• Publikační typ
• časopisecké články MeSH

This work aims to investigate the chemical and/or structural modification of Ti and Ti-6Al-4V (TiAlV) alloy surfaces to possess even more favorable properties toward cell growth. These modifications were achieved by (i) growing TiO2 nanotube layers on these substrates by anodization, (ii) surface coating by ultrathin TiO2 atomic layer deposition (ALD), or (iii) by the combination of both. In particular, an ultrathin TiO2 coating, achieved by 1 cycle of TiO2 ALD, was intended to shade the impurities of F- and V-based species in tested materials while preserving the original structure and morphology. The cell growth on TiO2-coated and uncoated TiO2 nanotube layers, Ti foils, and TiAlV alloy foils were compared after incubation for up to 72 h. For evaluation of the biocompatibility of tested materials, cell lines of different tissue origin, including predominantly MG-63 osteoblastic cells, were used. For all tested nanomaterials, adding an ultrathin TiO2 coating improved the growth of MG-63 cells and other cell lines compared with the non-TiO2-coated counterparts. Here, the presented approach of ultrathin TiO2 coating could be used potentially for improving implants, especially in terms of shading problematic F- and V-based species in TiO2 nanotube layers.

• Klíčová slova
• MG-63 cells, Ti foils, Ti-6Al-4V alloy, TiO2 nanotube layers, atomic layer deposition, cell proliferation,
• MeSH
• nanostruktury * chemie   MeSH
• slitiny farmakologie   chemie   MeSH
• testování materiálů MeSH
• titan * farmakologie   chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• slitiny MeSH
• titan * MeSH
• titanium alloy (TiAl6V4) MeSH Prohlížeč

Beta titanium alloy Ti-35Nb-6Ta-7Zr-0.7O (wt%) was developed as a material intended for the manufacturing of a stem of a hip joint replacement. This alloy contains only biocompatible elements and possesses a very high yield strength already in the cast condition (900 MPa). However, the porosity, large grain size and chemical inhomogeneity reduce the fatigue performance below the limits required for utilization in the desired application. Two methods of hot working, die forging and hot rolling, were used for processing of this alloy. Microstructural evolution, tensile properties and fatigue performance of the hot worked material were investigated and compared to the cast material. Microstructural observations revealed that porosity is removed in all hot-worked conditions and the grain size is significantly reduced when the area reduction exceeds 70%. Static tensile properties were improved by both processing methods and ultimate tensile strength (UTS) of 1200 MPa was achieved. Fatigue results were more reproducible in the hot rolled material due to better microstructural homogeneity, but forging leads to an improved fatigue performance. Fatigue limit of 400 MPa was achieved in the die-forged condition after 70% of area reduction and in the hot rolled condition after 86% of area reduction.

• Klíčová slova
• biomedicine, fatigue testing, hot working, tensile testing, titanium alloys,
• Publikační typ
• časopisecké články MeSH

The formation of nanostructures on titanium implant surfaces is a promising strategy to modulate cell adhesion and differentiation, which are crucial for future application in bone regeneration. The aim of this study was to investigate how the nanotube diameter and/or nanomechanical properties alter human osteoblast like cell (Saos-2) adhesion, growth and osteogenic differentiation in vitro. Nanotubes, with diameters ranging from 24 to 66 nm, were fabricated on a commercially pure titanium (cpTi) surface using anodic oxidation with selected end potentials of 10 V, 15 V and 20 V. The cell response was studied in vitro on untreated and nanostructured samples using a measurement of metabolic activity, cell proliferation, alkaline phosphatase activity and qRT-PCR, which was used for the evaluation of osteogenic marker expression (collagen type I, osteocalcin, RunX2). Early cell adhesion was investigated using SEM and ELISA. Adhesive molecules (vinculin, talin), collagen and osteocalcin were also visualized using confocal microscopy. Moreover, the reduced elastic modulus and indentation hardness of nanotubes were assessed using a TriboIndenter™. Smooth and nanostructured cpTi both supported cell adhesion, proliferation and bone-specific mRNA expression. The nanotubes enhanced collagen type I and osteocalcin synthesis, compared to untreated cpTi, and the highest synthesis was observed on samples modified with 20 V nanotubes. Significant differences were found in the cell adhesion, where the vinculin and talin showed a dot-like distribution. Both the lowest reduced elastic modulus and indentation hardness were assessed from 20 V samples. The nanotubes of mainly 20 V samples showed a high potential for their use in bone implantation.

• Publikační typ
• časopisecké články MeSH