Delivered by Ingenta to: University of Oxford IP : 129.67.19.65 Fri, 23 Mar 2012 14:40:16 RESEARCH ARTICLE Copyright © 2010 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Bionanoscience Vol. 4, 87–91, 2010 An Investigation on the Effect of Morphologies on Corrosion Behaviour of Nanostructured Hydroxyapatite-Titania Scaffolds Simantini Nayak † , Kamala Kanta Nanda, Purna C. Rath, Sarama Bhattacharjee, and Yatendra S. Chaudhary ∗‡ Colloids and Materials Chemistry Department, Institute of Minerals and Materials Technology (CSIR), Bhubaneswar 751013, India The viable application of hydroxyapatite (HAp) scaffolds requires to posses the unison of properties: porosity, bioactivity, mechanical toughness etc. Such properties strongly depend on the geometric factors such as the size, morphology/microstructure of HAp. We have developed a hydrothermal based approach to synthesize HAp-titania scaffold with different morphologies ranging from smooth film to cauliflower to urchin like structures. The structural characterization by XRD reveals the for- mation of HAp phase. The SEM analysis suggests the formation of HAp nanosheets or their sub- sequent assembly when reaction carried out under basic conditions without and with the oxidizing agent H 2 O 2 , respectively. The detailed investigation of corrosion behaviour of all HAp-titania scaffold samples was undertaken by potentiodynamic technique in Ringer’s simulated body fluid solution at close to human body temperature i.e., 37  C. The shift in the OCP values of HAp-titania scaffold samples towards nobler side and the relatively more posivite E corr values observed for these sam- ples than that of bare Ti-foil, suggesting superior corrosion resistance in case of HAp-titania scaffold samples than that of bare Ti-foil. The detailed results on structural characterization and discussion on corrosion behaviour of HAp-titania scaffold samples with different morphologies/microstructures are presented. Keywords: Hydroxyapatite, Nanostructure, Simulated Body Fluid, Corrosion, Scaffold. 1. INTRODUCTION The Titanium and its alloys have found extensive appli- cations as orthopedic implants in human body because of their higher strength than that of polymeric implants and high toughness than that of ceramic implants. 1 How- ever these metallic materials are susceptible to corrosion by body fluids, which may lead to infection, local pain, swelling and loosening and consequently the in vivo fail- ure of implant. 2 The human body shows natural reaction against prosthetic devices causing the osteolysis and has the tendency to isolate from the surrounding live tissues. Moreover, metallic surfaces are not adequately bioactive, in general, and surface modification is usually required ∗ Author to whom correspondence should be addressed. † Present address: Max-Planck-Institut für Eisenforschung, Düsseldorf, D-40237, Germany. ‡ Present address: Department of Chemistry, University of Oxford, South Parks Road, OX1 3QR, U.K. to improve the bioactivity so as to improve osteointegra- tion with bone tissues. To overcome these problems, Ti implants are generally coated with bio-active hydroxya- patite [(Ca 10 (PO 4  6 (OH) 2 ] (HAp)—a bio-ceramic which exhibit physico-chemical resemblance with mineral con- stituents of human bones and teeth. 3 The coating passi- vates the body fluid to come in direct contact with metal and hence minimizes the corrosion of implants. The ability of such HAp coatings helps to integrate implants to bone and support new bone generation. 4 Further, some in vitro studies have revealed that the surface parameters of bio implant scaffold such as topography may play an impor- tant role in growth of tissue, retaining their integrity, cell mobility and control over cellular activity. 5 The physico chemical and bio-physiological activity of HAp coating strongly depends upon geometrical factors such as particle size, dimensional anisotropy, morphology and microstruc- tures etc. Therefore, apart from the mechanical toughness, the unison of nanocrystalline nature, porosity and bioac- tivity, such that it may allow the growth of tissues within J. Bionanosci. 2010, Vol. 4, No. 1/2 1557-7910/2010/4/087/005 doi:10.1166/jbns.2010.1038 87