Nanoscience and Nanotechnology 2016, 6(1A): 18-24 DOI: 10.5923/c.nn.201601.03 Ionic Substituted Hydroxyapatite Scaffolds Prepared by Sponge Replication Technique for Bone Regeneration Uma Batra 1,* , Seema Kapoor 2 1 Department of Materials & Metallurgical Engineering, PEC University of Technology, Chandigarh, India 2 Dr. S.S. Bhatnagar University Institute of Chemical Engineering & Technology, Panjab University, Chandigarh, India Abstract Porous metallic implants used for replacement in fractures have well-documented fixation problems, and like natural bone, cannot self-repair or adapt to changing physiological conditions. As a consequence, the implant becomes loose over time. Bioactive ceramic alternatives have shown excellent potential in repair and regeneration of bone defects due to their ability to support bone cell growth and form strong bonds to both hard and soft tissues. This work deals with synthesis and characterization of biodegradable scaffolds with nano-hydroxyapatite (HA), zinc substituted nano-hydroxyapatite (ZnHA) and fluorine substituted nano-hydroxyapatite (FHA) particles for bone regeneration. The nanoparticles were synthesized via wet chemical method and scaffolds were fabricated using sponge replication technique. The elemental composition of nanoparticles was determined using XRF. The crystallography and functional groups were evaluated by XRD and FTIR spectroscopy, respectively. TEM images exhibited the as-synthesized nanoparticles size below 50nm. Zinc/fluorine substitution could affect the ratio of HA and β-TCP (β-tricalcium phosphate) phases in scaffolds. SEM images showed the presence of both macroporosity and microporosity in the scaffolds, with total porosity in the range of 65-75%. From the in-vitro study, it was confirmed that the obtained scaffolds were biomimetic, bioactive, and osteoconductive. Other than bone regeneration, the obtained scaffolds can have a wide array of applications, including tissue engineering, filtration, and catalyst support. The use of ionic substituted hydroxyapatite also opens new possibilities in the field of bone regeneration, utilizing the easily tailored bioactivity and biodegradation rates. Keywords Hydroxyapatite, Tricalcium phosphate, Scaffolds, Bioactivity, Bone regeneration, In-Vitro 1. Introduction The bone tissue engineering has focused on the use of natural or synthetic materials in the form of scaffolds as conduits to guide new bone growth in vivo (in the body). The success of tissue engineering is highly dependent upon the properties of the scaffold materials. As such there are four desired characteristics for an ideal material used for making scaffold including osteointegration, osteoconduc- tion, osteoinduction, and osteogenesis [1]. The first three characteristics can be achieved in both biological and synthetic materials, but it is the fourth characteristic that is currently only satisfied by apatitic scaffolds. Pore size, pore structure, surface topography, chemical composition and surface energy are other considerations [2]. The success of scaffolds in-vivo relies on their ability to induce surrounding tissue to invade, grow, and replace the implanted material [3]. In this context, various scaffolds such as HA, tricalcium phosphate (TCP), collagen, chitosan, * Corresponding author: umabatra2@yahoo.com (Uma Batra) Published online at http://journal.sapub.org/nn Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved polycaprolactone (PCL), and poly (lactic-co-glycolic acid) (PLGA), have been used [4], [5]. Biphasic calcium phosphate consists of a bioactive mixture of HA and β-TCP. An optimum balance of the more stable phase of HA and the more soluble β-TCP in scaffold material helps in gradual dissolution in the body, inducing bone regeneration at the expense of biphasic mixture. Moreover, such materials closely resemble natural bone; therefore, foreign body reactions are avoided and bone cells recognize the material. They can also be produced artificially with relative ease and their composition can be varied to alter the degree of biodegradability or to more accurately mirror the chemical composition of bone mineral. Zinc substitution, for example, has shown significant increase in bioactivity in-vitro and improved bone regeneration both in-vivo and clinically. Porous structures have been shown clinically to allow bone in-growth and to provide genuine solutions for the repair of bone defects. Various modifications such as substitution of desirable ions in apatite, addition of bioactive molecules or nanoparticles can enhance attachment and proliferation of stem cells on the scaffold [6-8]. These scaffolds are more bioactive and responsive to changes in their surrounding