Akermanite-based coatings grown by pulsed laser deposition for metallic implants employed in orthopaedics

Development of Vitroceramic Coatings and Analysis of Their Suitability for Biomedical Applications

“…The SEM images achieved on the surface of the films (Figure 2) highlight the formation of continuous and compact layers on top of titanium substrates, with spherical agglomerations of particles from place to place. The average grain size seemed to be slightly different from one sample to another, but ranging in 10-50 nm interval, with a visible decrease when raising the substrate temperature, an aspect that has been reported before [25]. Moreover, at lower magnification, specific deposition droplets could be observed, mostly for the lower temperature substrate and oxygen pressure, as well as the substrate surface features, with a certain rough pattern developed during metallic plates cutting and polishing.…”

“…The mineral coatings were obtained by pulsed laser deposition, using a target that was synthesized in our laboratory using a wet-chemistry approach; the details of this processing step, as well as the characteristics of the final ceramic disc, were included in a previous paper [25]. Briefly, the target composition was 0.38SiO 2 -0.04P 2 O 5 -0.3525CaO-0.18MgO-0.04ZnO-0.0075CaF 2 , alkoxides and nitrates being mainly employed as precursors for the sol-gel procedure.…”

“…The gel formed was dried, calcined, shaped and presintered, then the resulting powder was granulated, shaped and sintered in optimized conditions. The reasons for choosing such oxide system are detailed in previous papers [11,25]. Mainly, the content of SiO 2 , CaO and MgO ensures the positioning of the composition within the primary crystallization field of akermanite in the corresponding ternary system; SiO 2 and P 2 O 5 are network formers, while CaO, MgO and ZnO are network modifiers for glass; P 2 O 5 also contributes to apatite formation; CaO and MgO likewise sustain the mineralization process when introduced into the physiological environment; ZnO favours the emergence of a high surface area, while CaF 2 modifies the biochemical processes in a beneficial way.…”

“…The ceramic target employed for the PLD experiments was fabricated in our laboratory, being thermally treated at 1200 • C; the phase composition consisted of akermanite as major crystalline phase and diopside as minor crystalline phase, with a relatively dense appearance [25]. Figure 1a shows the XRD patterns of the four thin films grown by laser ablation on titanium substrates in different experimental conditions ( Table 2).…”

“…In this case, a commercial or custom-made ceramic target is ablated by a pulsed laser, a plume of plasma is generated and directed towards the metallic substrate, upon which it settles, forming a thin layer that physically binds to the support [23,24]. Our research group has already reported the growth of nanostructured akermanite-based thin films by pulsed laser deposition, with good biocompatibility and bioactivity [25]. Since both the target characteristics and processing conditions strongly influence the properties of the final coatings [26], more studies are necessary in order to elucidate which are the driven factors and optimized set of parameters.Thus, the aim of this work is to produce a material that is durable and readily implantable.…”