RESEARCH Part 2: biocompatibility evaluation of hydroxyapatite-based clinoptilolite and Al 2 O 3 composites C. Kalkandelen 1,2 & M. Suleymanoglu 3 & S. E. Kuruca 3 & A. Akan 4,1 & F.N. Oktar 5,6 & O. Gunduz 7,6 Received: 1 December 2016 /Revised: 26 January 2017 /Accepted: 30 January 2017 # Australian Ceramic Society 2017 Abstract The biocompatibility of clinoptilolite/alumina/bo- vine hydroxyapatite (Cp - A1 2 O 3 - BHA) composite, at dif- ferent ratio obtained by powder pressing process, were inves- tigated studying the behavior of osteosarcoma (SAOS-2) cells. The biocompatibility was examined by means of cytotoxicity and cytocompatibility tests. The structure and morphology of bioceramic composites were studied by scanning electron mi- croscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) technique. The results showed that these materials have no toxic effects. The natural composite that fabricated in this study may be a promising approach for bone- engineering applications. Keywords Bovine hydroxyapatite . Clinoptilolite . Alumina . Biocomposites . Biocompatibility Introduction Hydroxyapatite (HA) {Ca 10 (PO 4 ) 6 (OH) 2 } is one of the most well-known phosphates in the biologically active phosphate ceramic family [1]. Due to the poor mechanical properties of pure HA [2, 3], usually, HA-based composite materials are preferred for load-bearing biomedical applications and HA must be mixed with biocompatible materials [4, 5]. When considered in terms of biocompatibility properties, ce- ramic bone graft substitutes including HA, tricalcium phosphate (TCP), or their combinations have excellent biocompatibility and have been used experimentally and clinically for filling bone defects [6, 7]. Other materials such as phosphate ceramics and in these different bioglass compositions have been used as sintering aids to evaluate in sintering of HA or as a component of composite to enhance material and bioactivity properties [8]. Clinoptilolite (Cp) is also a member of the Zeolite family that is defined with the following basal formulations (Na,K,Ca) 4 Al 6 Si 30 O 72 .24H 2 O[9]. Zeolite in the form of Cp has an increasing potential in medical and industrial field [10, 11]. It’ s medical application fields are increasing rapidly. In vitro studies, showing similar behaviors like bioglass, draws attention for hard tissue applications. It has been also reported by Pavelić et al. that aluminosilicate particulates re- lates with specific cells and modifies their pathways. These reaction leads regulating of the gene expression. Especially in some in vivo studies on dogs and rats, it was reported that several zeolite compounds had inhibited the growth of some cancer cells [10, 11]. Moreover, Cp is a natural material, which includes trace elements that the silicon and low amounts containing zeolite was observed to improve bone formation [10]. Trace minerals are known to generally play a vital role in the human body homeostasis. Alumina (A1 2 O 3 ) is one of the most widely reported par- ticular biomaterial combinations used, which is used as an * C. Kalkandelen kalkan@istanbul.edu.tr 1 Biomedical Engineering, Ph.D. Program, Institute of Graduate Studies in Science and Engineering, Istanbul University, Istanbul, Turkey 2 Vocational School of Technical Sciences, Biomedical Devices Technology Department, Istanbul University, Istanbul, Turkey 3 Istanbul Faculty of Physiology, Istanbul University, Capa, Istanbul, Turkey 4 Department of Biomedical Engineering, Faculty of Engineering and Architecture, Izmir Katip Celebi University, Izmir 35620, Turkey 5 Department of Bioengineering, Faculty of Engineering, Marmara University, Istanbul, Turkey 6 Advanced Nanomaterials Research Laboratory, Marmara University, Goztepe Campus, 34722 Istanbul, Turkey 7 Department of Metallurgy and Materials Engineering, Faculty of Technology, Marmara University, Goztepe Campus, 34722 Istanbul, Turkey J Aust Ceram Soc DOI 10.1007/s41779-017-0027-9