Biomimetic coatings of calcium phosphates on titanium alloys
Biomedical Nanomaterials: From design to implementation, Institution of Engineering and Technology, ss.3-14, 2016
- Yayın Türü: Kitapta Bölüm / Araştırma Kitabı
- Basım Tarihi: 2016
- Yayınevi: Institution of Engineering and Technology
- Sayfa Sayıları: ss.3-14
- Sağlık Bilimleri Üniversitesi Adresli: Evet
Özet
Metallic orthopedic implants have been widely used to repair skeletal defects and poorly functioning joints for many years. Among them, titanium (Ti) and its alloys can be described as the most frequently used orthopedic metals, due to their unique properties, such as a good mechanical match with hard tissues, resistance to corrosion in body fluids, and being lightweight. However, Ti and its alloys fail to show bioactivity which is a very important issue for the integration of implants with bone tissue. Therefore, hydroxyapatite [HA, Ca10(PO4)6(OH)2], which is the main constituent of the inorganic part of natural bone, has been traditionally used as a coating to achieve the promoted bioactivity on the metallic implant surfaces. There are various techniques for coating HA on metallic implants such as plasma spraying, electrodeposition, pulsed-laser deposition, sputtering, sol-gel, and biomimetics. Simulated body fluid (SBF) used in biomimetic calcium phosphate (CaP) coatings basically mimics the inorganic composition, pH, and temperature of normal human blood plasma. Normally, a Ti alloy implant can be biomimetically coated in 14-28 days depending on the desired coating thickness if SBF solution is replenished every 2 days. Therefore, more concentrated formulations of SBF such as 1.5× SBF, 5× SBF, and 10× SBF were suggested for faster deposition rates with a drawback of decreased solution stability. To deposit CaPs on Ti alloy substrates, there are many different formulations of SBF with varying ionic compositions of certain ions, such as chloride (Cl-), bicarbonate (HCO3 -), and sulfate (SO4 2-), and with different buffers such as tri(hydroxymethyl)aminomethane (TRIS) and Hank's balanced salt solution (HEPES). In recent studies, it was shown that it is also possible to coat CaPs doped with specific ions or loaded with antibacterial agents and bone stimulating factors via biomimetic routes.