Synthesis and Characterization of Hydroxyapatite Powder from Natural Gypsum Rock Eko Pujiyanto 1,a , Pringgo Widyo Laksono 1,b and Joko Triyono 2,c 1 Industrial Engineering Department, Sebelas Maret University, Indonesia 2 Mechanical Engineering Department, Sebelas Maret University, Indonesia a ekop2003@yahoo.com, b widyolaksono@yahoo.com, c jokotri5528@gmail.com Keywords: Natural gypsum rock, hydroxyapatite powder and characterization Abstract. This study prepared hydroxyapatite powder that synthesized from natural gypsum rock and find out physical–chemical and cytotoxicity properties. The synthesis realized by reacting natural gypsum powder with 1M of (NH 4 ) 2 HPO 4 solutions using a microwave. Characterizations of natural gypsum powder and hydroxyapatite powder were conducted by XRD, XRF and SEM. In vitro cytotoxicity testings of hydroxyapatite powder were conducted by MTT method using vero cells. XRD patterns of gypsum powder closed to JCPDF 33-0311 (gypsum standard). Characteristics of gypsum powder i.e. contained 41.72% CaO, level of purity 91,6 % and crystal size 7,147 nm. Charateristic of hydroxyapatite powder that synthesized from natural gypsum powder i.e. contained 46.91% CaO and 40.20% P 2 O 5 , XRD patern closed to JCPDF 09-432 (hydroxyapatite standard), level of purity 99 % and crystal size 1.243 nm. There were not significantly difference in cytotoxicity properties of hydroxyapatite powder that synthesized from natural gypsum rock and commercial hydroxyapatite powder (p= 0.086). These results indicated hydroxyapatite powder that synthesized from natural gypsum rock possible to be used as bone substitutes. Introduction Hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] based biomaterials are being increasingly used as bone substitutes in dentistry and in reconstructive and in orthopedic applications because of their good biocompatibility properties [1]. Pure hydroxyapatite has chemical composition, biological and crystallographic closely similar with bone and teeth [2]. The present status of the pure hydroxyapatite as a biomaterial has already been well established [3]. Multiple methods have been used for preparation of hydroxyapatite powder, as reviewed in several works. Two main methods for preparation of hydroxyapatite powders are wet methods and solid state reactions. Hydroxyapatite powder have been synthesized from variety mineral, including coral, gypsum (CaSO 4 .2H 2 O) and calcite. Hydroxyapatite powder have been synthesized from gypsum waste using wet method [4]. Natural gypsum powder and hydroxyapatite powder that synthesized from natural gypsum powder are not know yet physical–chemical and cytotoxicity properties, whereas hydroxyapatite powder must be safe as bone substitutes. This paper reported characterization of natural gypsum powder and hydroxyapatite powder that synthesized from natural gypsum powder. Materials and Methods Synthesis of Hydroxyapatite Powder (HAg) from Natural Gypsum Powder The natural gypsum rock was sorted and washed with water for removal of sand and other impurities. The natural gypsum rock was crushed into powder gypsum. Twenty grams of gypsum powder was mixed in 800 mL of 1 M diammonium hydrogen phosphate [(NH 4 ) 2 HPO 4 ]. The solution in the pyrex glass was heated by microwave for 20 minutes. These processes result in hydroxyapatite (HAg) powder. HAg powder was cleaned with distilled water and was dried by microwave for 15 minutes. Advanced Materials Research Vol. 893 (2014) pp 56-59 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.893.56 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 141.0.11.122-05/02/14,03:02:59)