Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Mechanochemically synthesized phase stable and biocompatible β- tricalcium phosphate from avian eggshell for the development of tissue ingrowth system Uday Kiran Roopavath a,1 , Mahesh Kumar Sah a,b,1 , Bharat B. Panigrahi c , Subha Narayan Rath a,* a Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, 502285, Telangana, India b Department of Biotechnology, Dr. B.R. Ambedkar National Institute of Technology-Jalandhar, Jalandhar, 144 011, Punjab, India c Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, 502285, Telangana, India ARTICLE INFO Keywords: Eggshell waste Mechanical stimulation Ca(OH) 2 β-TCP Biphasic calcium phosphate Bone regeneration ABSTRACT Bioceramics obtained from naturally derived materials are gaining much interest as implants for bone and dental defects. The present study aims to synthesize phase stable β-tricalcium phosphate (β-TCP) from avian eggshell assisted with ball milling process followed by a wet chemical precipitation method (Group CPM). The effect of mechanical stimulation on phase conversion of CaO was also studied. The study was carried alongside the powders synthesized from chemical precursors (Group CPS) as well as eggshell derived powders without ball milling process (Group CPN). The phase behaviour and surface morphology were studied by XRD, FT-IR, and SEM analysis. Scaffolds were fabricated using sponge replication method to simulate a potential bone graft analogue. The cytocompatibility study was performed by human adipose-derived stem cells (ADSCs) over a period of 21 days by live-dead assay and Alamar blue dye reduction assay. The process of mechanically sti- mulating CaO precursor through extensive milling plays a major role on phase stabilization of β-TCP, as com- pared to the mixed phases of Hydroxyapatite (HAp) and β-TCP formed from unmilled CaO. Group CPN scaffolds were found to be biologically equivalent to group CPS scaffolds. This novel route, aided with ball-milling process for the synthesis of β-TCP from naturally occurring eggshell waste seems promising enough to replace com- mercially available β-TCP produced from harmful nitrate precursors and has the capability to develop im- plantable biomaterial for tissue regeneration. 1. Introduction Over the last few decades, efforts have been made to enhance the osteogenic activity of xenogeneic bone for clinical applications [1]. Nevertheless, this approach poses risk of adverse biological effects such as infection, immunogenic reactions and disease transfer, etc. [2]. Thus, in recent times, tissue engineering field has evolved as a promising approach to regrow, repair or replace the damaged bone with natural bone overtime. For this purpose, an ideal artificial substitute is needed that should be biocompatible, osteoinductive, osteoconductive with suitable mechanical properties to support the cell proliferation in vivo [3,4]. To find a bone substitute, researchers emphasize on biosimilar composition consisting of calcium phosphate (CaP) based matrix, con- taining collagen and other proteins [5]. CaP can be easily synthesized chemically and a number of reports have used the CaP scaffolds for bone tissue engineering [6]. However, the presence of precursor che- mical residues in the synthesized calcium phosphate is currently a limitation, and if those are not eliminated completely, it can be detri- mental to the living cells. In this context, natural resources have attracted researchers to de- code their biocompatibility, reproducibility, and processability to de- velop biomaterials [7]. Million tons of eggshell, produced and treated as bio-waste across the globe could be a good raw material for the value-added products. Eggshell consists of minerals (95.1%), proteins (3.3%), and water (1.6%). Calcium is the major mineral constituent existing mainly in its native crystalline form as calcium carbonate (93.6 wt% of total mineral) and calcium triphosphate (0.8%) with a very trace amount of magnesium carbonate [8]. Bioceramics synthe- sized from eggshell wastes are predicted to exhibit greater biocompat- ibility than other synthetic powders due to the presence of additional https://doi.org/10.1016/j.ceramint.2019.03.217 Received 29 November 2018; Received in revised form 24 March 2019; Accepted 27 March 2019 * Corresponding author. Department of Biomedical Engineering, Indian Institute of Technology Hyderabad (IITH), Kandi(V), Sangareddy(M), Medak District, 502 285, Telangana, India. E-mail address: subharath@iith.ac.in (S.N. Rath). 1 The authors contributed equally to the study. Ceramics International xxx (xxxx) xxx–xxx 0272-8842/ © 2019 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Uday Kiran Roopavath, et al., Ceramics International, https://doi.org/10.1016/j.ceramint.2019.03.217