Evaluation and regulation of the corrosion resistance of macroporous titanium scaffolds with bioactive surface films for biomedical applications

Fabrication of a TiO2@Cu Core-Shell Nanorod Array as Coating for Titanium Substrate with Mechanical and Chemical Dual Antibacterial Property

Titanium (Ti) is an excellent medical metal material, but the absence of good antibacterial property restricts its widespread application. To overcome this, we thus conducted a series of modifications for Ti. First, a titanium dioxide (TiO₂) nanorod array was generated on the Ti surface by hydrothermal treatment (TiO₂/Ti). With the polymer-mediated self-assembly method, a continuous copper (Cu) shell structure on the surface of the nanorod was then generated to form a TiO₂@Cu core-shell nanorod array as coating for Ti (TiO₂@Cu/Ti). Using pure Ti as the control group, the antibacterial properties of TiO₂/Ti and TiO₂@Cu/Ti were appraised. The results manifested that the mechanical and chemical dual function of the released Cu²⁺ and TiO₂ nanorod array could effectively kill bacteria on the surface of Ti. Besides, the obtained coating exhibited no cytotoxicity and favorable biocompatibility. In this work, we found an antibacterial strategy based on multiple sterilization pathways, which made Ti have good antibacterial property and further improved its biocompatibility.

Construction of a magnesium hydroxide/graphene oxide/hydroxyapatite composite coating on Mg–Ca–Zn–Ag alloy to inhibit bacterial infection and promote bone regeneration

The improved corrosion resistance, osteogenic activity, and antibacterial ability are the key factors for promoting the large-scale clinical application of magnesium (Mg)-based implants. In the present study, a novel nanocomposite coating composed of inner magnesium hydroxide, middle graphene oxide, and outer hydroxyapatite (Mg(OH)₂/GO/HA) is constructed on the surface of Mg-0.8Ca–5Zn-1.5Ag by a combined strategy of hydrothermal treatment, electrophoretic deposition, and electrochemical deposition. The results of material characterization and electrochemical corrosion test showed that all the three coatings have high bonding strength, hydrophilicity and corrosion resistance. In vitro studies show that Mg(OH)₂ indeed improves the antibacterial activity of the substrate. The next GO and GO/HA coating procedures both promote the osteogenic differentiation of MC3T3-E1 cells and show no harm to the antibacterial activity of Mg(OH)₂ coating, but the latter exhibits the best promoting effect. In vivo studies demonstrate that the Mg alloy with the composite coating not only ameliorates osteolysis induced by bacterial invasion but also promotes bone regeneration under both normal and infected conditions. The current study provides a promising surface modification strategy for developing multifunctional Mg-based implants with good corrosion resistance, antibacterial ability and osteogenic activity to enlarge their biomedical applications.

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A Mg(OH)₂/GO/HA composite coating with high bonding strength was constructed on the surface of Mg–Ca–Zn–Ag alloy.

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The outer HA layer with excellent osteogenic activity recovered the high corrosion resistance of inner Mg(OH)₂ layer.

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The Mg(OH)₂/GO/HA composite coating promoted new bone regeneration significantly under both normal and infected conditions.

A review on alloy design, biological response, and strengthening of β-titanium alloys as biomaterials

From the past few years, developments of β-Ti alloys have been the subject of active research in the medical domain. The current paper highlights significant findings in the area of β-Ti alloy design, biological responses, strengthening mechanisms, and developing low-cost implants with a high degree of biocompatibility. It is evident that an astonishing demand for developing the low modulus-high strength implants can be fulfilled by synchronizing β stabilizer content and incorporating tailored thermo-mechanical techniques. Furthermore, the biological response of the implants is as important as the physical properties that regulate healing response; hence, the optimum selection of alloying elements plays a curial role for clinical success. The paper also presents the evolution of patents in this field from the year 2010 to 2020 showing the relevant innovations that may benefit a wide range of researchers.

The optimized preparation of HA/L-TiO2/D-TiO2 composite coating on porous titanium and its effect on the behavior osteoblasts

Various surface bioactivation technology has been confirmed to improve the osteogenic ability of porous titanium (pTi) implants effectively. In this study, a three-layered composite coating, i.e. outer layer of hydroxyapatite (HA), middle layer of loose titanium dioxide (L-TiO₂) and inner layer of dense TiO₂ (D-TiO₂), was fabricated on pTi by a combined processing procedure of pickling, alkali heat (AH), anodic oxidation (AO), electrochemical deposition (ED) and hydrothermal treatment (HT). After soaking in simulated body fluid for 48 h, the surface of the AHAOEDHT-treated pTi was completely covered by a homogeneous apatite layer. Using MC3T3-E1 pro-osteoblasts as cell model, the cell culture revealed that both the pTi without surface treatment and the AHAOEDHT sample could support the attachment, growth and proliferation of the cells. Compared to the pTi sample, the AHAOEDHT one induced higher expressions of osteogenesis-related genes in the cells, including alkaline phosphatase, Type I collagen, osteopontin, osteoclast inhibitor, osteocalcin and zinc finger structure transcription factor. As thus, besides the good corrosion resistance, the HA/L-TiO₂/D-TiO₂-coated pTi had good osteogenic activity, showing good potential in practical application for bone defect repair.