TiO2 bioactive implant surfaces doped with specific amount of Sr modulate mineralization

Abstract

One of the main problems that remain in the implant industry is poor osseointegration due to bioinertness of implants. In order to promote bioactivity, calcium (Ca), phosphorus (P) and strontium (Sr) were incorporated into a TiO 2 porous layer produced by micro-arc oxidation. Ca and P as bioactive elements are already well reported in the literature, however, the knowledge of the effect of Sr is still limited. In the present work, the effect of various amounts of Sr was evaluated and the morphology, chemical composition and crystal structure of the oxide layer were investigated. Furthermore, in vitro studies were carried out using human osteoblast-like cells.The oxide layer formed showed a triplex structure, where higher incorporation of Sr increased Ca/P ratio, amount of rutile and promoted the formation of SrTiO 3 compound. Biological tests revealed that lower concentrations of Sr did not compromise initial cell adhesion neither viability and interestingly improved mineralization. However, higher concentration of Sr (and consequent higher amount of rutile) showed to induce collagen secretion but with compromised mineralization, possibly due to a delayed mineralization process or induced precipitation of deficient hydroxyapatite. Ca-P-TiO 2 porous layer with less concentration of Sr seems to be an ideal candidate for bone implants.

Preliminary Investigation on Degradation Behavior and Cytocompatibility of Ca-P-Sr Coated Pure Zinc

“…Besides, it has to be mentioned that Ca and Sr may be other factors that promote cell proliferation, since Ca and Sr are important components during bone formation. Extensive studies have demonstrated that the introduction of Ca and Sr in the coatings greatly favors excellent cell proliferation and ALP activity of osteoblasts [34,35]. In this study, the presence of Ca and Sr possibly helped to promote cell proliferation and ALP activity.…”

Incorporation of inorganic elements onto titanium-based implant surfaces by one-step plasma electrolytic oxidation: an efficient method to enhance osteogenesis

“…The morphology of coatings after PEO features a rough surface with numerous highly interconnected micropores, which are distributed homogeneously and ranging at micro levels, 164 and it is often described as "craterlike" and "volcano-like" in the literature. 23,101 Furthermore, small grains in the nanoscale range are revealed in high-magnification analysis. 36,43,113,117,130,136,144,163,173 Importantly, the incorporation of inorganic elements rarely affects the morphology including pore size and pore distribution (Fig.…”

“…2). 23,43,101,104,109,114,121,152 This unique morphology of PEO coatings is believed to ameliorate the process of osseointegration since the porous structure can optimize the implantbone interface from both macro (strong mechanical interlocking: the ingrowth of bone) and micro (suitable micro-environment for cells: large and interconnected growing space) dimensions. Interestingly, a study conducted by Li et al has represented a novel "cortex-like" micro/nano dual-scale structured TiO 2 coating manufactured by micro-arc oxidation (MAO) with tetraborate electrolytes (Fig.…”

Surface Modification of TiO2 Nanotubes Prepared by Porous Titanium Anodization via Hydrothermal Reaction: A Method for Synthesis High-Efficiency Adsorbents of Recovering Sr Ions

“…Strontium ion (Sr 2+ ) is one of the rare-earth metals widely used in manufacturing, such as ferrite magnets, ceramics, glass, and fireworks. 27,31 The concentration of Sr 2+ in natural seawater is about 7 mg•L −1 . The recycling of Sr 2+ from seawater is simpler, less costly, and more environmentally friendly than the traditional extraction method of mining ores on land.…”

“…Seawater is rich in mineral resources, including dissolved metals in the form of ions. Strontium ion (Sr 2+ ) is one of the rare-earth metals widely used in manufacturing, such as ferrite magnets, ceramics, glass, and fireworks. , The concentration of Sr 2+ in natural seawater is about 7 mg·L –1 . The recycling of Sr 2+ from seawater is simpler, less costly, and more environmentally friendly than the traditional extraction method of mining ores on land. − At present, the commonly used adsorbents for extracting Sr 2+ from seawater are mainly alginate microbeads. − The disadvantage of these materials is that the alginate is prone to over-swelling by absorbing water and transforming into hydrogel .…”