Pulsed laser deposition of strontium-substituted hydroxyapatite coatings

摘要

The growing evidence of the beneficial role of strontium in bone has increased the interest of developing strontium-containing biomaterials for medical applications, and specifically biocompatible coatings that can be deposited on metallic implants to benefit from their load-bearing capabilities. In this work, strontium-substituted hydroxyapatite (Sr-HA) coatings have been fabricated by pulsed laser deposition (PLD) from initial targets obtained after mixing and compacting commercial HA and SrCO_3 powders in different proportions. The films thus fabricated were then structurally, morphologically and chemically characterized using scanning electron microscopy, optical profilometry, X-ray diffraction, Fourier-transform infrared spectroscopy. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The macroscopic morphology of the films presented in all cases equivalent spherical shaped aggregates of typical calcium phosphate coatings. The results reveal, however, the incorporation of Sr~(2+) and carbonate groups in the coatings as a function of the SrCO_3 content in the ablation target, being the incorporation of Sr~(2+) a linear phenomenon that is accompanied by a similarly linear withdrawal of Ca~(2+). The role of Sr~(2+) in the modification of the HA structure and a possible mechanism of substitution of Sr~(2+) atoms in place of Ca~(2+) atoms are discussed.