Synthesis, characterization, and coating of forsterite (Mg₂SiO₄) based material over medical implants: A review

Abstract

Biocompatible metallic alloys (stainless steel, Ti-alloy, Co–Cr alloys, etc.) have been frequently used for various biomedical implants. Being biocompatible, complications like implant corrosion, body inflammation, organ pain, local infection, and cytotoxicity cannot be avoided. Hydroxyapatite, a common biomaterial, is used in the form of powders, coatings, and composites for biomedical applications. But poor adhesion, poor load-bearing capacity, high dissolution, poor wear resistance, natural fragility, etc. are the few hindrances in the use of hydroxyapatite coating over implants. Hence, there is a need to focus on the development of alternative biomaterials and their coatings for metallic (orthopedic, dental, metallic stents, pacemakers, etc.) implants. To avoid various complexities and to improve the biocompatibility of metal implants, the coating of forsterite and its composites are being used nowadays. Techniques like dip coating, plasma spraying, and electrophoretic deposition are employed for such coatings. In this paper, a review based on methods of preparation of forsterite has been done. For the preparation of forsterite powder, various studies have reported the sintering temperature range to be 800–1450 ℃ and the crystallite size from 10 nm to 100 µm. The forsterite and its composites coating over Ti-alloy and stainless steel have also been reported. This paper also compares the mechanical and biological properties of forsterite and hydroxyapatite. It has been observed that the mechanical properties (hardness, fracture toughness, Young’s modulus, and compressive strength), and biological properties (biocompatibility and bioactivity) of forsterite are favorable for the biomedical implant coating.

Low velocity oxy fuel spraying of hydroxyapatite coating on a multifunctional UNS S31254 austenitic stainless steel

“…Hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ) is a bio-ceramic material having chemical characteristics very similar to the human bone and teeth (∼70% by weight). 14,15 It is certainly capable of supporting bone growth and provides structural support to living tissues in several applications. HAp tends to form biocompatible phases and reduces the risk of any allergic reactions, crucial for successful implantation into the human body.…”