Boutinguiza et al. Nanoscale Research Letters 2011, 6:255 http://www.nanoscalereslett.com/content/6/1/255 N A N O E X P R E S S Open Access Production of nanoparticles from natural hydroxylapatite by laser ablation Mohamed Boutinguiza*†, Rafael Comesaña†, Fernando Lusquiños†, Antonio Riveiro† and Juan Pou† Abstract Laser ablation of solids in liquids technique has been used to obtain colloidal nanoparticles from biological hydroxylapatite using pulsed as well as a continuous wave (CW) laser. Transmission electron microscopy (TEM) measurements revealed the formation of spherical particles with size distribution ranging from few nanometers to hundred nanometers and irregular submicronic particles. High resolution TEM showed that particles obtained by the use of pulsed laser were crystalline, while those obtained by the use of CW laser were amorphous. The shape and size of particles are consistent with the explosive ejection as formation mechanism. Introduction Nanoparticles represent an important object of investiga- tion in the field of biomaterials due to the new properties and functionalities obtainable when operating at nanos- cale [1-3]. Calcium phosphate compounds in particular are getting special attention as biomaterials due their characteristics to induce bone-integration and to anchor rigidly prostheses or implants to the bone [4]. Among them hydroxylapatite (HA), Ca10(PO4)6(OH)2, has a spe- cial importance because of its similarities with the mineral constituents of bones and teeth, where this mate- rial is present as nanometric particles with a platelet shape [5] giving them their physiochemical properties. On the other hand, it has been reported that the use of b-tricalcium phosphate (b-TCP), Ca3(PO4)2 in nanosize scale and low crystallinity improves the bioactivity [6,7]. There are different and diverse techniques for produ- cing calcium phosphate nanoparticles, such as aqueous solutions [8], the templating technique to achieve nano- porous hydroxylapatite structure [9], or the microwave irradiation to synthesize hydroxylapatite nanostructures [10], etc. In this work, we report the results of calcium phosphate nanoparticles obtained from calcined fish bones using laser ablation in de-ionized water. This tech- nique offers some advantages: direct formation of nano- particles in solutions, the absence of contamination, all * Correspondence: mohamed@uvigo.es † Contributed equally Dpto. Física Aplicada, Universidad de Vigo, Lagoas-Marcosende, 9, Vigo 36310, Spain particles are collected, easiness of preparation, low costs of processing, etc. In previous works, we obtained calcium phosphate micro and nanoparticles from fish bones by laser abla- tion in ambient conditions [11] and laser-induced frac- ture [12]. In the present study, we report the production of b-TCP and HA nanoparticles from a natural source such as calcined fish bones. Experimental procedure The powder used as starting material was obtained from fish bones according to the following procedure. The fish bones were boiled in water for 1 h and washed using a strong water jet to eliminate the fish meat. The washed fish bones were then dried and heated in air at 950°C for 12 h. The calcined samples were milled during 1 min. Pellets of the obtained product were prepared as precur- sor material to be ablated in de-ionized water by two dif- ferent lasers operating at 1064 and 1075 nm wavelength, respectively. The first system used was a pulsed Nd:YAG laser delivering a maximum average power of 500 W. The laser beam was coupled to an optical fiber of 400 μm diameter and focused onto the upper surface of the target by means of 80 mm of focal length lens, where the spot diameter at normal incidence for a pulsed laser was about 0.14 mm. Other parameters were varied as follows: laser pulse width 1 to 3 ms, frequency 5 to 10 Hz, and pulse energy 2 to 8 J. The second laser system used was a monomode Ytterbium-doped fiber laser. This laser works in continuous wave mode delivering a maximum average power of 200W. Its high beam quality allowed setting the © 2011 Boutinguiza et al; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.