The development of new materials with antibacterial properties and the scope to decrease or eliminate the excessive antibiotic use is an urgent priority due to the growing antibiotic resistance-related mortalities. New bone substitute materials with intrinsic antibacterial characteristics are highly requested for various clinical applications. In this study, the choice of copper ions as substitutes for calcium in tricalcium phosphate (TCP) has been justified by their pronounced broad-spectrum antibacterial properties. Copper-substituted TCP (Cu-TCP) ceramics with the copper content of 1.4 and 0.1 wt% were synthesized by mechano-chemical activation. X-ray diffraction (XRD) analyses established that both pure and copper-containing compounds adopted the structure of whitlockite (β-TCP). XRD and electron paramagnetic resonance (EPR) spectroscopy revealed the partial isovalent substitution of calcium ions with copper ions in the β-TCP lattice. With the use of infrared and EPR spectroscopies, it was detected that carbonate ions got incorporated into the β-TCP structure during the synthesis procedure. By releasing the tension in the M(5)O6 octahedron consequential to the lower CaO bond length than the corresponding sum of ionic radii, the substitution of calcium with smaller copper ions stabilizes the structure of β-TCP. As concluded form the thermal analyses, the introduction of Cu prevented the polymorphic transformation of β- to α-TCP. At the same time, the introduction of Cu to the β-TCP structure enhanced the crystal growth and porosity of the ceramics, which had a positive effect on the cytocompatibility of the material. The MTT colorimetric assay showed that the metabolic activity of the mouse fibroblast NCTC L929 cell line during 24 h of incubation with 3-day extracts from Cu-TCP (1.4 wt%) and β-TCP pellets in the cell culture medium was similar to the negative control, indicating the absence of any inhibitory effects on cells. The seeding and the growth of human dental pulp stem cells on the surface of Cu-TCP (1.4 wt%) and β-TCP ceramics also showed the absence of any signs of cytotoxicity. Finally, microbiological assays demonstrated the antibacterial activity of Cu-TCP ceramics against Escherichia coli and Salmonella enteritidis, whereas β-TCP did not exhibit such an activity. Overall, the addition of Cu ions to β-TCP improves its antibacterial properties without diminishing the biocompatibility of the material, thus making it more attractive than pure β-TCP for clinical applications such as synthetic bone grafts and orthopaedic implant coatings.

由于与抗生素耐药性相关的死亡率不断增加，开发具有抗菌特性的新材料以及减少或消除过度使用抗生素的范围是当务之急。具有内在抗菌特性的新型骨替代材料在各种临床应用中具有很高的需求。在这项研究中，选择铜离子作为磷酸三钙 (TCP) 中钙的替代物，因其显着的广谱抗菌特性而被证明是合理的。通过机械化学活化合成了铜含量分别为 1.4 和 0.1 wt% 的铜取代 TCP (Cu-TCP) 陶瓷。X 射线衍射 (XRD) 分析确定纯化合物和含铜化合物均采用白铁矿 (β-TCP) 结构。XRD 和电子顺磁共振 (EPR) 光谱揭示了钙离子在 β-TCP 晶格中被铜离子部分等价取代。使用红外光谱和 EPR 光谱，检测到碳酸根离子在合成过程中结合到 β-TCP 结构中。通过释放 M(5)O6 八面体中的张力，从而导致较低的 CaO 键长度比相应的离子半径总和，用较小的铜离子取代钙稳定了 β-TCP 的结构。根据热分析得出的结论，Cu 的引入阻止了 β- 到 α-TCP 的多晶型转变。同时，将Cu引入β-TCP结构增强了陶瓷的晶体生长和孔隙率，对材料的细胞相容性产生了积极影响。MTT 比色法显示，小鼠成纤维细胞 NCTC L929 细胞系在与细胞培养基中的 Cu-TCP（1.4 wt%）和 β-TCP 沉淀物的 3 天提取物孵育 24 小时期间的代谢活性类似于阴性对照，表明对细胞没有任何抑制作用。人牙髓干细胞在Cu-TCP表面的播种和生长(1. 4 wt%) 和 β-TCP 陶瓷也没有显示出任何细胞毒性迹象。最后，微生物测定证明了 Cu-TCP 陶瓷对大肠杆菌和肠炎沙门氏菌，而 β-TCP 则没有这种活性。总体而言，在 β-TCP 中添加 Cu 离子可在不降低材料生物相容性的情况下提高其抗菌性能，从而使其在合成骨移植物和骨科植入物涂层等临床应用中比纯 β-TCP 更具吸引力。