Contents lists available at ScienceDirect Materials Science & Engineering C journal homepage: www.elsevier.com/locate/msec Review Natural calcium phosphates from fish bones and their potential biomedical applications Pınar Terzioğlu a,b , Hamdi Öğüt c , Ayşe Kalemtaş b, ⁎ a Muğla Sıtkı Koçman University, Muğla Vocational School, Department of Chemistry and Chemical Processing Technologies, Muğla, Turkey b Bursa Technical University, Faculty of Engineering and Natural Sciences, Department of Metallurgical and Materials Engineering, Bursa, Turkey c Bursa Technical University, Faculty of Engineering and Natural Sciences, Department of Bioengineering, Bursa, Turkey ARTICLE INFO Keywords: Bioceramic Fish bone Calcination Natural hydroxyapatite β-tricalcium phosphate ABSTRACT The treatment and recovery of bio-wastes have raised considerable attention both from the environmental and economic point of view. Every year, a remarkable amount of fish processing by-products are generated and dumped as waste from all over the world. Fish bones can serve as a raw material for the production of high value-added compounds that can be used in various sectors including agrochemical, biomedical, food and pharmaceutical industries. The calcination of fish bones results in a single phase (hydroxyapatite) or bi-phasic (hydroxyapatite-tricalcium phosphate) bioceramics depending on the processing conditions as well as the content of the fish bones. This review summarizes the literature on the production of hydroxyapatite from fish bones and discusses their potential applications in biomedical field. The effect of processing conditions on the properties of final products including Ca/P ratio, crystal structure, particle shape, particle size and biological properties are presented in the light of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric-differential thermal analysis, bioactivity and biocompatibility investigations. 1. Introduction Hydroxyapatite (HA) ceramics have been widely used as a bioma- terial, e.g. implant, and are produced from organic or inorganic mate- rials. HA ceramics produced from organic materials are preferred due to its close chemical content and physical properties. It was demonstrated that HA ceramics produced from natural sources show no cellular toxicity, no fibrous tissue generation around the healing area. Also, inflammatory and pyrogenetic responses are missing in and around the transplant area [1–3]. Commercial CaP ceramics are mainly prepared from synthetic raw materials using several methods including crystal growth under hy- drothermal conditions [4–7], microwave irradiation [8, 9], layer hy- drolysis of other calcium phosphate salts [10, 11], mechanochemical synthesis [12–14], plasma techniques [15, 16], solid-state reactions [17–20], and sol-gel processing [21–23]. However, generally expensive reagent grade chemicals are used in the preparation of synthetic cal- cium phosphate ceramics coupled with complex and time-consuming techniques [24–26]. HA and tricalcium phosphate (TCP) can also be extracted from natural sources simply and economically with various environmental benefits [27]. Antler, tooth and bones of various natural animal sources have been used for the production of CaP ceramics including bovine [28–31], crocodile [32], chicken [25], cow [33], deer [34], goat [35, 36], Meleagris gallopova [37], sheep [24, 38] and pig [33, 39]. Among natural marine sources of HA and TCP such as corals [40–42], clam shells [43], oyster shells [44, 45], razor shells [46], mussel shells [47], sea urchin spines [48, 49], sea snail shells [50–52] and sea shells [53–56], fish bones [57–62] are promising, abundant, and low-cost alternatives. The present comprehensive review evaluates the literature on the chemical composition, structural properties, and applications of calcium phosphates derived from various fish bones. Food waste, waste disposal and by-product management are issues generating concerns for aquatic and terrestrial environments as well as economic and food security issues. [63, 64] The rapid growing fishing industry is a significant part of the food industry and roughly > 91 million tons of fish and shellfish are consumed annually. [59] Several by-products, accounting about 40–50% of the total fish, are discharged as wastes during the processing [65]. Fish bones are huge fish proces- sing by-products, usually recognized as an impracticable and a worth- less waste. To the best of our knowledge, there is no consensus on any proper treatment procedure to evaluate fish bones in the market. Consequently, fish bones are generally used for the production of an- imal meal if an animal feed production facility is nearby, providing only a limited benefit. [59] Recently, evaluation of fish bones as a source of https://doi.org/10.1016/j.msec.2018.06.010 Received 8 September 2017; Received in revised form 31 May 2018; Accepted 9 June 2018 ⁎ Corresponding author. E-mail address: ayse.kalemtas@btu.edu.tr (A. Kalemtaş). Materials Science & Engineering C 91 (2018) 899–911 Available online 11 June 2018 0928-4931/ © 2018 Published by Elsevier B.V. T