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.

Zinc and zinc alloys have been studied due to their corrosion properties as potentially biodegradable materials. In this study, a zinc/hydroxyapatite composite (Zn/HA) containing 16 wt % HA was prepared by spark plasma sintering and characterized in detail. The microstructure, mechanical and corrosion properties were studied and the mutual relations between properties and microstructure were found. The porosity was evaluated to be approximately 18%. The mechanical properties (ultimate compression strength = 65 MPa and ultimate flexural strength = 120 MPa) are sufficient for the potential scaffolding and augmentation of cancellous bone. The flexural properties of these materials were measured for the first time. Immersion tests and subsequent analyses confirmed no direct participation of hydroxyapatite in the corrosion process and an ideal corrosion rate of approximately 0.4 mm/year. The amount of released zinc was between 4–6 mg/day corresponding with the maximal usable surface area of 25 cm². All the results suggest that the Zn/HA composite is suitable as a potential biodegradable material (from the point of view of mechanical and corrosion properties) for the replacement of cancellous bones.

Zinc and its alloys belong to a group of biodegradable materials, which can be potentially used for the preparation of temporary orthopedic implants. The research of biodegradable zinc materials revealed a lot of limitations; however, the new processing approaches of those materials can enhance their properties, which are insufficient for now. In this study, the zinc composite with 8 wt.% of hydroxyapatite (Zn/HA8) prepared for the first time by extrusion process was characterized from the point of view of the structural, mechanical and corrosion properties. The extrusion process led to good integrity of the interfaces between the zinc and hydroxyapatite particles. Mechanical behavior confirmed the role of hydroxyapatite as a defect in the material structure, which led to a decrease of the Zn/HA8 mechanical properties by approximately 30% (compressive yield strength (CYS) = 154 MPa Zn, 113 MPa Zn/HA8). Despite that, the Zn/HA8 composite showed sufficient mechanical properties for cancellous bone replacement and reached the lower limit for cortical bone. Additionally, the presence of hydroxyapatite caused the preferential precipitation of hydroxyapatite (HA) from the solution and can lead to a significant enhancement of the tissue/implant interface interactions.

Additive manufacturing is currently one of the promising methods for the fabrication of products of complex shapes. It is also used in medical applications, thanks to technological progress, which also enables the printing of metallic materials. However, the final products often have to undergo a final surface treatment. In this work, the influence of surface finishing on the corrosion behavior of the medical alloy Ti-6Al-4V prepared by the selective laser melting technique is studied. The samples were subjected to mechanical, chemical and electrochemical treatments. Corrosion behavior was investigated using DC and AC electrochemical techniques such as potentiodynamic and potentiostatic curves and electrochemical impedance spectroscopy. Furthermore, the influence of surface treatments on the possibility of localized corrosion attack was evaluated. The results showed that the surface treatments have a positive effect on the corrosion resistance and reduce the risk of crevice corrosion.

In this study, advanced techniques such as atom probe tomography, atomic force microscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy were used to determine the corrosion mechanism of the as-ECAPed Zn-0.8Mg-0.2Sr alloy. The influence of microstructural and surface features on the corrosion mechanism was investigated. Despite its significance, the surface composition before exposure is often neglected by the scientific community. The analyses revealed the formation of thin ZnO, MgO, and MgCO₃ layers on the surface of the material before exposure. These layers participated in the formation of corrosion products, leading to the predominant occurrence of hydrozincite. In addition, the layers possessed different resistance to the environment, resulting in localized corrosion attacks. The segregation of Mg on the Zn grain boundaries with lower potential compared with the Zn-matrix was revealed by atom probe tomography and atomic force microscopy. The degradation process was initiated by the activity of micro-galvanic cells, specifically Zn – Mg₂Zn₁₁/SrZn₁₃. This process led to the activity of the crevice corrosion mechanism and subsequent attack to a depth of 250 μm. The corrosion rate of the alloy determined by the weight loss method was 0.36 mm·a⁻¹. Based on this detailed study, the degradation mechanism of the Zn-0.8Mg-0.2Sr alloy is proposed.