Hydroxyapatite [Hap, Ca₁₀(PO₄)₆(OH)₂] is one of the most preferred bioceramic material for orthopedic implants and coatings due to its stoichiometric similarities with human hard tissues. However, foreign body implantation inside human body sometimes leads to bacterial film formation over the implant surface causing the implant failure, thereby needing a revision surgery. This study attempts to select the better dopant between zinc (Zn) and cobalt (Co) as per the antibacterial efficacy when doped in Hap. To prepare antibacterial transition‐metal‐doped Hap, Zn and Co are doped in Hap as per the chemical formula Ca_10−x M_x (PO₄)₆(OH)₂, (M = Zn or Co and x  = 0.24) to improve antibacterial efficacy. Phase and microstructural characterization by Rietveld refinement, scanning electron microscopy (SEM), and Fourier transformation infrared spectroscopy (FT‐IR) confirms the doping. Evaluation of antibacterial activity against E coli reveals that both Zn‐ and Co‐doped Hap shows antibacterial property with the latter being more effective (zone of inhibition ~3 mm more) for the same level of doping. Inductively coupled plasma‐mass spectrometry confirms the presence of ~676 ppb Co⁺² and ~303 ppb Zn⁺² after leaching. In addition, cytotoxicity assay with NIH3T3 cell line reveals cytocompatibility of both the compositions with either dopant. The effect of spark plasma sintering on densification and mechanical properties of Co‐doped Hap is investigated for the first time and compared with Hap with the same level of Zn doping. It appears that Co‐doped Hap attains higher densification (~7% more) and fracture toughness (~2 times better) as compared to that of Zn‐doped counterpart (densification: 86% and fracture toughness: 0.75 ± 0.12 MPa √m). Thus, this study suggests that Co‐ and Zn‐doped Hap are promising candidates for bone tissue engineering with improved antibacterial properties and in addition, Co‐doped Hap can attain higher density and offer better fracture toughness than that of Hap doped with Zn.

中文翻译：

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锌和钴掺杂对火花等离子体烧结羟基磷灰石的抗菌作用和细胞相容性的影响

羟基磷灰石[Hap，Ca ₁₀（PO ₄）₆（OH）₂ ]是骨科植入物和涂层的最优选生物陶瓷材料之一，因为它与人体硬组织的化学计量相似。然而，异物植入人体内有时会导致在植入物表面上形成细菌膜，从而导致植入物失效，因此需要翻修手术。这项研究试图根据在Hap中掺杂时的抗菌功效，在锌（Zn）和钴（Co）之间选择更好的掺杂剂。为了制备抗菌过渡金属掺杂的Hap，按照化学式Ca _{10− x} M _x （PO ₄）_6将Zn和Co掺杂在Hap中。（OH）₂，（M = Zn或Co，x  = 0.24），以提高抗菌功效。通过Rietveld精炼，扫描电子显微镜（SEM）和傅立叶变换红外光谱（FT-IR）进行相和微结构表征可以确认掺杂。对大肠杆菌的抗菌活性的评估表明，Zn和Co掺杂的Hap均显示出抗菌性能，在相同的掺杂水平下ZnP和Co掺杂的Hap均更有效（抑制区多出约3 mm）。电感耦合等离子体质谱法确认存在〜676 ppb Co ⁺²和〜303 ppb Zn ⁺²浸出后。另外，使用NIH3T3细胞系的细胞毒性测定揭示了两种组合物与任一掺杂剂的细胞相容性。首次研究了火花等离子体烧结对共掺杂Hap的致密化和力学性能的影响，并将其与相同水平的Zn掺杂的Hap进行了比较。似乎与锌掺杂的合金相比，共掺杂的堆具有更高的致密性（约高7％）和断裂韧性（约2倍）（致密化为86％，断裂韧性为0.75±0.12 MPa√m）。 。因此，这项研究表明，Co和Zn掺杂的Hap是具有改善的抗菌性能的骨组织工程的有前途的候选者，此外，Co掺杂的Hap可以比掺杂Zn的Hap获得更高的密度和更好的断裂韧性。