Hydroxyapatite, a biomaterial: Its chemical synthesis, characterization and study of biocompatibility prepared from shell of garden snail, Helix aspersa

Abstract

The shell of garden snail (Helix aspersa) is basically made of calcium carbonate. An attempt is made to convert calcium carbonate of garden snail shell to hydroxyapatite. The snail shell was found to decompose within 850$^{\circ}$C to all the carbonate phases. The calcined snail shells were then treated with acids followed by different chemicals in ammoniacal media maintaining proper stoichiometry to produce fine hydroxyapatite (HAP) as filter cake with a Ca$/$P molar ratio of 1${\cdot }$67. The dried HAP powder was extremely pure with a specific surface area of 15 m$^{\bf 2}/$g. The different characterization techniques were adopted both for calcined snail shell and HAP synthesized by X-ray diffraction (XRD), thermal analysis (DTA$/$TGA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The surface area and particle size of HAP powder prepared by chemical precipitation route, were also determined by BET and Malvern particle size analyser, respectively. The synthesized powder was soaked in stimulated body fluid (SBF) medium for various periods of time in order to evaluate its bioactivity. The changes of pH of SBF medium were measured. High bioactivity of prepared HAP powder due to the formation of apatite on its surface was observed.