The first calcium phosphate based biomaterials were introduced in the market almost forty years ago and, due to the compositional resemblance with the mineral constituents of bones and teeth, they became extensively employed in biomedical applications involving bone defects repair. Nowadays, research on calcium phosphate biomaterials is focused on developing the potential of additional dimensional and morphological similarities to those biological structures. Thus, specific physiochemical properties of hydroxylapatite (HA), Ca10(PO4)6(OH)2, are considered to be influenced by its presence as nanometric particles with a platelet shape in bones and teeth. Moreover, the use of β-tricalcium phosphate (β-TCP), Ca3(PO4)2 in nanosize scale and low crystallinity has been reported to improve the bioactivity.
Among the different methods of nanoparticle production, laser ablation is a powerful technique to improve the dimensional and morphological characteristics of calcium phosphate biomaterials. Direct formation of nanoparticles in solutions, the absence of contamination, maximum particle collection efficiency, easiness of preparation, or low processing costs constitute some of the advantages of this technique. In this work, we report the results of nanoparticles obtained by laser ablation of calcium phosphate targets in liquid media. Different infrared laser sources, operating at wavelengths 1064, 1075 and 10600 nm and coupled to identical focal length focusing heads were employed to study the influence of processing conditions, such as pulse energy, operating frequency, or irradiance, on the properties of the produced nanoparticles. The morphology and the composition of these calcium phosphate nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and conventional and high resolution transmission electron microscopy (TEM, HRTEM).