In Vitro Evaluation of Ag- and Sr-Doped Hydroxyapatite Coatings for Medical Applications

Osseointegration plays the most important role in the success of an implant. One of the applications of hydroxyapatite (HAp) is as a coating for metallic implants due to its bioactive nature, which improves osteoconduction. The purpose of this research was to assess the in vitro behavior of HAp undoped and doped with Ag and/or Sr obtained by galvanostatic pulsed electrochemical deposition. The coatings were investigated in terms of chemical bonds, contact angle and surface free energy, electrochemical behavior, in vitro biomineralization in acellular media (SBF and PBS), and biocompatibility with preosteoblasts cells (MC3T3-E1 cell line). The obtained results highlighted the beneficial impact of Ag and/or Sr on the HAp. The FTIR spectra confirmed the presence of hydroxyapatite within all coatings, while in terms of wettability, the contact angle and surface free energy investigations showed that all surfaces were hydrophilic. The in vitro behavior of MC3T3-E1 indicated that the presence of Sr in the HAp coatings as a unique doping agent or in combination with Ag elicited improved cytocompatibility in terms of cell proliferation and osteogenic differentiation. Therefore, the composite HAp-based coatings showed promising potential for bone regeneration applications.

Automated summary

This study assessed the in vitro behavior of hydroxyapatite (HAp) coatings doped or undoped with Ag and/or Sr, obtained through galvanostatic pulsed electrochemical deposition. The results showed the beneficial impact of Ag and/or Sr on HAp, with the presence of hydroxyapatite confirmed in all coatings. Moreover, the coatings exhibited hydrophilic surfaces. The biocompatibility evaluation revealed that the inclusion of Sr, either alone or in combination with Ag, improved cell proliferation and osteogenic differentiation. Consequently, the composite HAp-based coatings demonstrated promising potential for bone regeneration applications.