Comparison of hydrophilic and hydrophobic nano topographic surfaces of titanium alloys on pre-osteoblastic cell interaction.

This work aimed to assess the influence of different structured substrates with hydrophilic and hydrophobic properties on micro and nano topographies developed on titanium alloys over pre-osteoblastic cell behavior. Nano topography influences small dimension levels of cell morphology by inducing filopodia formation in cell membranes, irrespectively to the wettability behavior of the surface. Therefore, micro and nanostructured surfaces of titanium-based samples using different techniques of surface modification processing, such as chemical treatments, micro-arc anodic oxidation (MAO), and MAO combined to laser irradiation were developed. Isotropic and anisotropic texture morphologies, wettability, topological parameters and compositional alterations were measured after the surface treatments. Finally, cell viability, adhesion and morphological responses were assessed to investigate the influence of distinct topologies on osteoblastic cells aiming to encounter the conditions to better promote mineralization events. Our study demonstrated that the hydrophilic behavior improves cell adhesion, amplified when effective surface area increases. Surfaces presenting nano topography have a direct influence on cell morphology and play a key role for filopodia formation.

Strontium-loaded titanium-15molybdenum surface improves physicochemical and biological propertiesin vitro.

The titanium alloy composition and microdesign affect the dynamic interplay between the bone cells and titanium surface in the osseointegration process. The current study aimed to evaluate the surface physicochemical properties, electrochemical stability, and the metabolic response of the MC3T3-E1 cells (pre-osteoblast cell line) cultured onto titanium-15molybdenum (Ti-15Mo) discs treated with phosphoric acid (H3PO4) and sodium hydroxide (NaOH) and/or strontium-loading by the hydrothermal method. The x-ray dispersive energy spectroscopy (EDS) and x-ray diffraction (XRD) analysis showed no trace of impurities and the possible formation of hydrated strontium oxide (H2O2Sr), respectively. The confocal laser microscopy (CLSM) analysis indicated that titanium samples treated with strontium (Sr) showed greater surface roughness. The acid/alkali treatment prior to the hydrothermal Sr deposition improved the surface free energy and resistance to corrosion of the Ti-15Mo alloy. The acid/alkali treatment also provided greater retention of the Sr particles on the Ti-15Mo surfaces accordingly with inductively coupled plasma optical emission spectrometry (ICP-OES) analysis. The AlamarBlue and fluorescence analysis indicated noncytotoxic effects against the MC3T3-E1 cells, which allowed cells' adhesion and proliferation, with greater cells' spreading in the Sr-loaded Ti-15Mo samples. These findings suggest that Sr deposition by the hydrothermal method has the potential to enhance the physicochemical properties of the Ti-15Mo previously etched with H3PO4and NaOH, and also improve the initial events related to cell-mediated bone deposition.

Analysis of the mechanical and physicochemical properties of Ti-6Al-4 V discs obtained by selective laser melting and subtractive manufacturing method.

The surface properties of titanium and its alloys are commonly modified by different techniques, including additive manufacturing (AM), to improve the osseointegration of dental implants. The aim of this study was to evaluate and compare the wettability, topography, chemistry, and structure of titanium-aluminum-vanadium (Ti-6Al-4 V) discs fabricated by selective laser melting (SLM) and subtractive manufacturing (conventional machining). Three different groups were evaluated: selective laser melting (SLM); conventional machining with H3 PO4 + NaOH surface treatment (CM + ST); and conventional machining without surface treatment (CM), including analysis of wettability and roughness, morphological and chemical analyses by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), and structural characterization analysis by computed tomography (micro-CT), and X-ray diffraction (XRD). The results showed that SLM surface had higher roughness (9.09 ± 1.94 Ra; 51.93 ± 11.59 Rz; 11.03 ± 1.95 Sa) and lower wettability (103.23° ± 13) than CM (0.06 ± 0.01 Ra; 0.42 ± 0.078 Rz; 0.07 ± 0.01 Sa) (76.95° ± 4.18) and CM + ST (0.17 ± 0.38 Ra; 0.88 ± 0.15 Rz; 0.18 ± 0.04 Sa) (18.55° ± 6.47) (p < 0.05). SEM images also proved the higher roughness of SLM surface, and CM + ST discs showed a topography resembling a sponge, characteristic of the nanometric treatment applied. EDX and XRD found no differences between the different surfaces, and micro-CT demonstrated the solid characteristic of the SLM disc. Compared with conventional machining, the SLM technique resulted in higher roughness and lower wettability. Meanwhile, the chemical properties and structure of the titanium alloy was not altered by the technique.

Biological response of chemically treated surface of the ultrafine-grained Ti-6Al-7Nb alloy for biomedical applications.

BACKGROUND: Nanophase surface properties of titanium alloys must be obtained for a suitable biological performance, particularly to facilitate cell adhesion and bone tissue formation. Obtaining a bulk nanostructured material using severe plastic deformation is an ideal processing route to improve the mechanical performance of titanium alloys. By decreasing the grain size of a metallic material, a superior strength improvement can be obtained, while surface modification of a nanostructured surface can produce an attractive topography able to induce biological responses in osteoblastic cells. METHODS: Aiming to achieve such an excellent synergetic performance, a processing route, which included equal channel angular pressing (ECAP), hot and cold extrusion, and heat treatments, was used to produce a nanometric and ultrafine-grained (UFG) microstructure in the Ti-6Al-7Nb alloy (around of 200 nm). Additionally, UFG samples were surface-modified with acid etching (UFG-A) to produce a uniform micron and submicron porosity on the surface. Subsequently, alkaline treatment (UFG-AA) produced a sponge-like nanotopographic substrate able to modulate cellular interactions. RESULTS: After several kinds of biological tests for both treatment conditions (UFG-A and UFG-AA), the main results have shown that there was no cytotoxicity, expressed alkaline phosphatase activity and total protein amounts without statistical differences compared to control. However, the UFG-AA samples presented an attractive effect on the cell membranes, and cell adhesions were preferentially induced as compared with UFG-A. Both conditions demonstrated cell projections, but for UFG-AA, cells were more widely dispersed, and more quantities of filopodia formation could be observed. CONCLUSION: Herein, the reasons for such behaviors are discussed, and further results are presented in addition to those mentioned above.