Surface morphology and in vitro bioactivity of biocompatible hydroxyapatite coatings on medical grade S31254 steel by RF magnetron sputtering deposition

Abstract

Hydroxyapatite (HA) is popularly used as a biocompatible coating material for metallic implants, in view of its improved bone fixation property, leading to an increased life of the implant. However, the deposition of HA on medical grade UNS S31254 stainless steel (SS254) for orthopaedic implant applications by the radio-frequency magnetron sputtering technique is unreported in the literature so far. The surface morphology of the deposited HA coatings was characterised using scanning electron microscopy and atomic force microscopy, while their phase composition was determined using X-ray diffraction. The thickness and adhesive strength of the HA coatings were determined using an ellipsometer and a tensometer, respectively. Finally, the antibacterial efficacy and bioactivity of the deposited coatings were confirmed using fluorescence activated cell sorting and immersion testing in simulated body fluid environment. The results obtained showed that the HA coatings grown on SS254 using magnetron sputtering possess desirable surface properties as well as good adhesion and biocompatibility properties, ideally suited for potential applications in orthopaedic implants.

Keywords:

• Coating
• Hydroxyapatite
• Magnetron sputtering
• 254 stainless steel
• Implant

Acknowledgements

The use of synthesis, testing and characterisation facilities of the Centre for Interdisciplinary Research (CIR), Centre for Medical Diagnostic and Research (CMDR), Biotechnology and Applied Mechanics Departments, MNNIT, Allahabad, are gratefully acknowledged. Thanks are also due to Dr Naresh Kumar and Mr Aashish Jha for their valuable contribution in the experimental work. The authors would like to thank the Ministry of Human Resource Development, Government of India, and the University of Johannesburg, South Africa, for providing financial support.