Preparation of nanohydroxyapatite from skipjack tuna bone (Katsuwonus pelamis) by alkaline hydrolysis and thermal calcination methods

Abstract

As the main component of bones and teeth, hydroxyapatite (HAp) is considered a vital biomaterial in many fields. Meanwhile, fishbone by-products are abundant sources of HAp. Therefore, this study was conducted to prepare nano HAp from skipjack tuna bone (Katsuwonus pelamis) using alkaline hydrolysis and thermal calcination methods. After pre-treatment of fish bones for removing organic impurities, the bone powders were under alkaline hydrolysis in 1 M NaOH solution at 250o C for 1 hour. This method allows to obtain HAp nanopowders with an average particle size of only 22 nm; whereas, when heating at 600o C for four hours, the calcium formed was on average larger (40 nm) in size than the alkaline hydrolysis product. The HAp nanopowders formed by alkaline hydrolysis had a molar ratio of Ca/P 1.929, higher than that of the calcinated sample (1.848). These Ca/P molar ratios prove that the nano-HAp powders are B-type biological hydroxyapatites confirmed by the FTIR spectrum. In addition, the heavy metal contents of calcium powders are detected within safety limits of regulatory requirements of Vietnam regulations on dietary supplements and functional foods.