Influence of Applied Voltages on Mechanical Properties and In-Vitro Performances of Electroplated Hydroxyapatite Coatings on Pure Titanium

Abstract

Titanium and its alloys have been extensively used in biomaterials due to their bone-compatible modulus, superior bio-compatibility and enhanced corrosion resistance. But the metal implants that contact the body will release ions and scraps. In this study, Hydroxyapatite (HA, Ca 10 (PO 4 ) 6 (OH) 2 ) was coated on a pure Ti substrate by electrochemical deposition process, which can provide a well-controlled process and product. Across various applied voltages, the electroplated HA/Ti composites were evaluated on their chemical and mechanical performances and the behaviors of in-vitro simulating tests. Highly pure HA coatings were obtained with additional voltages from 16 V to 19 V. In addition, their mechanical properties were significantly enhanced with increasing voltages. With the results of in-vitro evaluations, the electroplated HA/Ti composites is capable of serving as a biomaterial for bone substitution or implantation. Biomaterials are synthetic materials that function in vivo or in vitro while physically in contact with the human body. Due to the coexistence with blood and body fluids, an ideal biomaterial must be biocompatible, nontoxic, stable, easily-manufactured and with proper mechanical properties.1,2 For an implantation, the main purpose is repairing the loss of tissues or organs to restore their original functions; thus, biocompatibility is the most concerning factor.Human tissues are roughly divided into two categories: soft and rigid. A bone is a rigid organ that constitutes parts of the skeleton. Bones further support and protect the organs of the body, enable human mobility, produce red and white blood cells and also store minerals. While bone tissues age and are damaged by external forces, they have an inherent ability to regenerate. However, an excessive bone loss requires the use of bone grafts. And while graft materials regularly originate from the same individual (autograft), a donor (allograft) or animal bone (heterograft), artificial biomaterials are attracting more and more interest in the field of tissue engineering. 3,4 The metallic materials known and widely used for medical implants in bone reconstructive surgery and prosthetic treatment are stainless steel (316L), Co-Cr alloys and unalloyed Ti.5-10 However, some chromic or nickel ions could be released into the body due to metallic fatigue and corrosion, resulting in inflammation or toxicity. 11Moreover, implanted hard tissues might cause a stress-shielding effect and bone resorption reactions because of the elastic incoordination with surrounding bones. For actual biomedical applications, considering mechanical properties and stability, titanium and its alloys are still selected for replacing supports in the human body, including artificial joints, bones, stents, tooth roots and other implanted artificial substitute materials. 12Hydroxyapatite (HA, Ca 10 (PO 4 ) 6 (OH) 2 ) is a major composition of human bones and also a popular ceramic material used in orthopedics. After implantation, the calcium and phosphorus ions could be r...

In Vitro Corrosion and Biocompatibility of Brushite/Hydroxyapatite Coatings Obtained by Galvanic Deposition on 316LSS

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Improved corrosion protection of titanium implant material by crystallographic texturing of Sr doped calcium phosphate electrodeposits

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