R. Narayanan

Surface modification of titanium and titanium alloys by ion implantation

Titanium and titanium alloys are widely used in biomedical devices and components, especially as hard tissue replacements as well as in cardiac and cardiovascular applications, because of their desirable properties, such as relatively low modulus, good fatigue strength, formability, machinability, corrosion resistance, and biocompatibility. However, titanium and its alloys cannot meet all of the clinical requirements. Therefore, to improve the biological, chemical, and mechanical properties, surface modification is often performed. In view of this, the current review casts new light on surface modification of titanium and titanium alloys by ion beam implantation.

Nanocrystalline hydroxyapatite coatings from ultrasonated electrolyte: preparation, characterization, and osteoblast responses.

An electrochemical method of producing nanograined hydroxyapatite coatings on titanium surface is reported in this article. The electrolyte contained Ca(NO(3))(2) and NH(4)H(2)PO(4) in the molar ratio of 1.67:1. The electrolyte had physiological pH and was ultrasonically agitated throughout the time of electrolysis. Coatings were deposited for 30 minutes at 10 and 15 mA/cm(2) and contained monohydroxyapatite phase whose grain sizes were 18 and 25 nm, respectively. These sizes are comparable with the grain size of bone. Small globules of hydroxyapatite covered the coating surface completely. Cell viability and total protein assay studies were carried out using SaOS-2 human osteoblast-like cell line. Of the two, the coating produced at 10 mA/cm(2) showed higher viability and protein activity and seems to be a promising material for osseointegration.

Combustion Synthesis of Hydroxyapatite and Hydroxyapatite (Silver) Powders

Hydroxyapatite powder is produced using combustion synthesis method. The powder was produced using a low-temperature processing method involving time as short as 15 minutes. As silver is known to have anti-bacterial properties, silver-doped hydroxyapatite was also produced by the same method. Both the powders were fully crystalline. XRD indicated the presence of an additional phase of CaO in both the samples. FT-IR indicated the presence of hydroxide, phosphate and carbonate groups. Silver addition tends to control the reactions of powder with a test Tris buffer environment and maintain a stable pH for a longer period of 500-hour duration.