Physicochemical properties, acute and subchronic toxicity of nano-hydroxyapatite obtained from Lates calcarifer fish bone

Abstract

As the main component of bones and teeth, hydroxyapatite (HAp) is considered a vital biomaterial in many fields. Meanwhile, fishbone by-products were used as abundant and cheap sources of natural HAp. The preparation of nano-HAp from fish bones not only contributes to increasing the value of by-products but also minimizes negative impacts on the environment. In this study, nano-HAp was successfully obtained from Lates calcarifer fish bone by the thermal calcination method. Analysis of SEM, TEM showed that the HAp nanopowders possessed an average size of 39.42 nm. The Ca/P molar ratio of 1.845 indicated that the nano-HAp powders were B-type biological hydroxyapatites, which has been confirmed by FTIR spectrum. In addition, the content of heavy metals including As, Pb, Hg, Cd and the microbial contamination are within safety limits of regulatory requirements of Vietnam regulation and US Pharmacopeia for food and dietary supplement standard. The other elements such as Fe, K, Mg, Na, Se, Zn are also present in nano-HAp. The investigation of acute toxicity shows that nano-HAp did not exhibit toxicity in Swiss mice at the highest dose of 6000 mg/kg body weight. The results of subchronic oral toxicity testing indicated that nano-HAP did not affect the behavior, body weight and hematological parameters of rabbits at doses of 50 and 100 mg/kg body weight for 28 days. The liver function indices (AST, ALT, GGT) and kidney function index (creatinine) are within normal limits. These properties suggest that nano-HAp from Lates calcarifer fish bones can be used as material in food and medicine fields.