We report on biological-derived hydroxyapatite (HA, of animal bone origin) doped with lithium carbonate (Li-C) and phosphate (Li-P) coatings synthesized by pulsed laser deposition (PLD) onto Ti6Al4V implants, fabricated by the additive manufacturing (AM) technique. After being previously validated by in vitro cytotoxicity tests, the Li-C and Li-P coatings synthesized onto 3D Ti implants were preliminarily investigated in vivo, by insertion into rabbits’ femoral condyles. The in vivo experimental model for testing the extraction force of 3D metallic implants was used for this study. After four and nine weeks of implantation, all structures were mechanically removed from bones, by tensile pull-out tests, and coatings’ surfaces were investigated by scanning electron microscopy. The inferred values of the extraction force corresponding to functionalized 3D implants were compared with controls. The obtained results demonstrated significant and highly significant improvement of functionalized implants’ attachment to bone (p-values ≤0.05 and ≤0.00001), with respect to controls. The correct placement and a good integration of all 3D-printed Ti implants into the surrounding bone was demonstrated by performing computed tomography scans. This is the first report in the dedicated literature on the in vivo assessment of Li-C and Li-P coatings synthesized by PLD onto Ti implants fabricated by the AM technique. Their improved mechanical characteristics, along with a low fabrication cost from natural, sustainable resources, should recommend lithium-doped biological-derived materials as viable substitutes of synthetic HA for the fabrication of a new generation of metallic implant coatings.

中文翻译：

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体内评估在3D打印植入物中掺锂的生物衍生羟基磷灰石涂层功能性骨的增强：在兔的初步研究。

我们报告了通过脉冲激光沉积（PLD）在Ti6Al4V植入物上合成的，通过增材制造（ AM）技术。在事先通过体外细胞毒性测试验证后，通过插入兔子的股骨dy，对在3D Ti植入物上合成的Li-C和Li-P涂层进行了初步的体内研究。用于测试3D金属植入物拔出力的体内实验模型用于本研究。植入四周和九周后，通过拉伸试验将所有结构从骨骼上机械去除，并通过扫描电子显微镜研究涂层的表面。将推断出的对应于功能化3D植入物的拔出力值与对照进行比较。获得的结果表明，功能化植入物与骨骼的附着力显着和高度显着改善（相对于对照，p值≤0.05和≤0.00001）。通过执行计算机断层扫描可以证明所有3D打印的Ti植入物都正确地放置在周围骨中，并很好地集成到了周围的骨头中。这是有关通过PLD在AM技术制造的Ti植入物上合成的Li-C和Li-P涂层进行体内评估的专门文献中的第一份报告。它们的改善的机械特性以及来自天然，可持续资源的低制造成本，应推荐掺锂的生物来源材料作为合成HA的可行替代品，以制造新一代金属植入物涂层。