Hydroxyapatites of Marine Origin as Sustainable Candidates for Implantology

Medical-grade titanium implants were functionalized with hydroxyapatite (HA) coatings of marine origin (derived from fish bones or sea-shells) by Pulsed laser deposition technique. Lithium phosphate, magnesium fluoride and silver were used as doping agents in three different concentrations, of 0.5, 1 and 2 wt.%, respectively. Besides morphological, structural and compositional investigations, the synthesized coatings were also submitted to mechanical testing.

SEM analysis revealed surfaces with rough morphologies, made of generally round-shaped particulates. This type of surface was shown to determine a good adhesion of grown cells and excellent in situ anchorage of implants. XRD and FT-IR investigations demonstrated the synthesis of coatings with different degrees of crystallinity, generally influenced by the concentration of the dopant and the source material. Compositional tests evidenced the presence of trace-elements generally found in the composition of the bone mineral phase, which play a key-role in its functionality. Surfaces with a strong hydrophilic behavior were demonstrated by contact angle measurements. The inferred pull-out bonding strength adherence values were three times higher than the ones imposed by international standard (> 15 MPa) in the case of implant coatings with high biomechanical loads.

Taking into consideration their improved mechanical characteristics and the morphological, structural and compositional results, along with the fact that the base materials are cheap and derived from sustainable resources, one can conclude that these marine-derived materials should be considered as viable candidates to HA synthetic ones, for implant coating applications.

Acknowledgements: Project no. PN-III-P1-1.1-TE2019-1449 (TE 189/2021) and Core Programme 16N/2019.