A comparative study of thermal calcination and an alkaline hydrolysis method in the isolation of hydroxyapatite from Thunnus obesus boneby Jayachandran Venkatesan, Zhong Ji Qian, BoMi Ryu, Noel Vinay Thomas, Se Kwon Kim

Biomed. Mater.

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Year
2011
DOI
10.1088/1748-6041/6/3/035003
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Chemistry (miscellaneous) / Mechanics of Materials / Business and International Management

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A comparative study of thermal calcination and an alkaline hydrolysis method in the isolation of hydroxyapatite from Thunnus obesus bone

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Biomed. Mater. 6 (2011) 035003 (12pp) doi:10.1088/1748-6041/6/3/035003

A comparative study of thermal calcination and an alkaline hydrolysis method in the isolation of hydroxyapatite from Thunnus obesus bone

Jayachandran Venkatesan1, Zhong Ji Qian2, BoMi Ryu1,

Noel Vinay Thomas1 and Se Kwon Kim1,2,3 1 Department of Chemistry, Pukyong National University, Busan 608-737, Korea 2 Marine Bioprocess Research Center, Pukyong National University, Busan 608-737, Korea

E-mail: sknkim@pknu.ac.kr

Received 7 January 2011

Accepted for publication 14 February 2011

Published 13 April 2011

Online at stacks.iop.org/BMM/6/035003

Abstract

In the present study, hydroxyapatite (HAp) was isolated from Thunnus obesus bone using alkaline hydrolysis and thermal calcination methods. The obtained ceramic has been characterized by thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), powder x-ray diffraction analysis (XRD), field-emission scanning electron microscopy, energy-dispersive x-ray analysis, transmission electron microscopy (TEM), selected area diffraction analysis, cytotoxic analysis and cell proliferation analysis. The results indicate that there are significant differences between the ceramics and T. obesus bone. FT-IR and TGA results affirmed that the collagen and organic moieties have been eliminated by both the proposed methods. XRD results were in agreement with JCPDS data. TEM and selective area diffraction images have signified that the thermal calcination method produces good crystallinity with dimensions 0.3–1.0 μm, whereas the alkaline hydrolysis method produces nanostructured HAp crystals with 17–71 nm length and 5–10 nm width. Biocompatibility of

HAp crystals was evaluated by cytotoxicity and cell proliferation with human osteoblast-like cell MG-63. (Some figures in this article are in colour only in the electronic version) 1. Introduction

Bone is a complex living tissue with hierarchical structure that consists of 70% calcium phosphate mineral (mostly nanoscale hydroxyapatite (HAp) crystals) and 30% organic moieties (including collagen, glycoproteins, proteoglycans, and sialoproteins) by dry weight. In recent years, significant progress has been made in organ transplantation, surgical reconstruction and the use of artificial prostheses to treat the loss or failure of an organ or tissue. Autograft and allograft are considered as ideal procedures for bone grafting. In the autograft procedure, bone is harvested from another part of 3 Author to whom any correspondence should be addressed. the body and is used to fill the gap or to graft the damaged bone that provides optimal osteoinductive, osteoconductive, and osteogenic properties. In the allograft procedure, cadaver bones are used that can provide osteoinductive and osteoconductive properties. However, both grafting procedures have their own disadvantages; autograft often leads to complications in wound healing, additional surgery, donor pain and an inadequate supply of bone to fill the gap. Allograft has problems with unwanted immunological responses and the risk of acquiring diseases transmissible (AIDS and hepatitis) by tissues and fluids [1, 2]. Due to the limited supply of natural bone for grafting, the need for synthetic bone substitutes which possess the same physiochemical and biological properties as 1748-6041/11/035003+12$33.00 1 © 2011 IOP Publishing Ltd Printed in the UK

Biomed. Mater. 6 (2011) 035003 J Venkatesan et al natural bone is ever increasing. These limitations and concerns have created substantial interest in the development of artificial materials as bone graft substitutes.

Calcium phosphate mineral, hydroxyapatite Ca10 (PO4)6(OH)2 (HAp), is considered to play a vital role in various fields including spinal fusion, craniomaxillofacial reconstruction, bone defects, fracture treatment, total joint replacement (bone augmentation), revision surgery [3, 4], catalysis, fertilizers and pharmaceutical products, bone tissue engineering, protein chromatography, water treatment processes, and the preparation of biocompatible materials [5, 6]. HAp is the most stable calcium phosphate salt at room temperature and pH between 4 and 12. HAp derived from the powder processing method has great potential as a bone substitute, owing to its excellent biocompatible and osteoconductive properties. Several methods have been reported for the synthesis of HAp crystals in the literature, including hydrothermal [7], liquid membrane [8], precipitation [9], radio frequency thermal plasma [10], ultrasonic precipitation [11], reverse micro emulsion [12], sol–gel [13] and polymer-assisted methods [14]. Most of the procedures for synthesizing HAp are biologically hazardous and they have a complicated process. Moreover, most of the synthetic procedures followed until now have led to the formation of non-stoichiometric products [5]. Synthetic HAp with a Ca/P ratio near 1.67 is stable when sintered in dry or wet air below 1200 ◦C. However at higher temperatures HAp loses its OH groups gradually and is transformed to oxyapatite

Ca10O(PO4)6 or Ca(PO4)6O, and at 1450 ◦C oxyapatite dissociates into the products α-Ca3(PO4)2, Ca2P2O7 and

Ca4P2O9 [15]. Difficulties encountered in preparing synthetic

HAp crystals from aqueous solutions are mainly caused by the high chemical affinity of the materials to some ions, the complex nature of the calcium phosphate system, and the roles of kinetic parameters that depend on the experimental conditions, prevailing over the thermodynamics [5]. To produce biologically compatible HAp, avoiding sophisticated methods that are used in synthetic procedures, some researchers have driven their focus in extracting HAp from natural biowaste such as animal bone and teeth.