Antibacterial properties and regenerative potential of Sr2+ and Ce3+ doped fluorapatites; a potential solution for peri-implantitis

Scaffolds and implants in orthopaedics and regenerative dentistry usually fail because of bacterial infections. A promising solution would be the development of biomaterials with both significant regenerative potential and enhanced antibacterial activity. Working towards this direction, fluorapatite was synthesised and doped with Sr2+ and Ce3+ ions in order to tailor its properties. After experiments with four common bacteria (i.e. E. Coli, S. Aureus, B. Subtilis, B. Cereus), it was found that the undoped and the Ce3+ doped fluorapatites present better antibacterial response than the Sr2+ doped material. The synthesised minerals were incorporated into chitosan scaffolds and tested with Dental Pulp Stem Cells (DPSCs) to check their regenerative potential. As was expected, the scaffolds containing Sr2+-doped fluorapatite, presented high osteoconductivity leading to the differentiation of the DPSCs into osteoblasts. Similar results were obtained for the Ce3+-doped material, since both the concentration of osteocalcin and the RUNX2 gene expression were considerably higher than that for the un-doped mineral. Overall, it was shown that doping with Ce3+ retains the good antibacterial profile of fluorapatite and enhances its regenerative potential, which makes it a promising option for dealing with conditions where healing of hard tissues is compromised by bacterial contamination.

骨科与再生牙科领域的支架与植入物常因细菌感染而失效。开发兼具优异再生性能与强化抗菌活性的生物材料，是颇具前景的解决方案。为此，科研人员合成了氟磷灰石（fluorapatite），并通过掺杂Sr²+与Ce³+离子对其性能进行精准调控。通过对四种常见致病菌（即大肠杆菌（E. Coli）、金黄色葡萄球菌（S. Aureus）、枯草芽孢杆菌（B. Subtilis）、蜡样芽孢杆菌（B. Cereus））开展抗菌实验后发现，未掺杂氟磷灰石与Ce³+掺杂氟磷灰石的抗菌效果均优于Sr²+掺杂氟磷灰石。将合成的矿物掺入壳聚糖支架中，并与牙髓干细胞（Dental Pulp Stem Cells, DPSCs）共培养以评估其再生潜能。正如预期，掺入Sr²+掺杂氟磷灰石的支架展现出优异的骨传导性，可促使牙髓干细胞向成骨细胞分化。Ce³+掺杂材料也得到了相似结果：其骨钙素浓度与RUNX2基因表达水平均显著高于未掺杂矿物组。综上，研究表明Ce³+掺杂既保留了氟磷灰石优良的抗菌性能，又提升了其再生潜能，使其成为应对因细菌污染导致硬组织愈合受阻病症的极具潜力的候选方案。