Hu Ruibo, Deng Leyi, Hao Xiaoying, Chen Jiadong, Zhou Xianfeng, Sahai Nita
School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909, USA.
College of Material Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
Materials (Basel). 2024 Sep 24;17(19):4688. doi: 10.3390/ma17194688.
Periodontitis and caries, while seemingly innocuous medical conditions, actually pose significant challenges because of their potential etiology with far more serious conditions. Efficacious treatment is hindered by bacterial antibiotic resistance. Standard AgNPs are ineffective against periodontal anaerobic bacteria, because they require oxidative dissolution to release Ag ions, which are the actual antimicrobial agents, but oxidation is not possible under anaerobic conditions. Prior studies on Ag-based periodontal antimicrobial materials either did not confirm a silver oxidation state or did not use strictly anaerobic growth media or both, causing spurious antimicrobial efficacy estimates. Here, we prove that silver ion-doped hydroxyapatite nanoparticles (AgHAp NPs) synthesized at various pHs contain an Ag oxidation state and directly release Ag even in a strictly anerobic medium. Thus, these AgHAp NPs exhibit direct antimicrobial activity against the fastidious anaerobic Gram-negative periodontal bacterium () and against caries-causing aerobic, Gram-positive bacterium (). The synthesis pH (6-11) correlates inversely with the Ag content (4.5-0.45 wt %) of AgHAp NPs and, hence, with antimicrobial efficacy, thus providing tunable efficacy for the target application. AgHAp NPs had greater antimicrobial efficacy than Ag-containing AgNPs and were less cytotoxic to the mouse fibroblast L929 cell line. Thus, AgHAp NPs (especially AgHAp7) are superior to AgNPs as effective, broad-spectrum, biocompatible antimicrobials against both anaerobic periodontal and aerobic dental bacteria. AgHAp NP synthesis is also inexpensive and scalable, which are significant factors for treating large global populations of indigent people affected by periodontitis and dental caries.
牙周炎和龋齿虽然看似是无害的病症，但由于其潜在病因可能引发更为严重的疾病，实际上带来了重大挑战。细菌对抗生素的耐药性阻碍了有效治疗。标准的银纳米颗粒对牙周厌氧菌无效，因为它们需要通过氧化溶解来释放银离子（实际的抗菌剂），但在厌氧条件下无法发生氧化。先前关于银基牙周抗菌材料的研究要么未确认银的氧化态，要么未使用严格的厌氧生长培养基，或者两者皆未做到，导致对抗菌效果的估计出现偏差。在此，我们证明在不同pH值下合成的银离子掺杂羟基磷灰石纳米颗粒（AgHAp NPs）含有银的氧化态，并且即使在严格的厌氧培养基中也能直接释放银。因此，这些AgHAp NPs对挑剔的厌氧革兰氏阴性牙周细菌（ ）和致龋需氧革兰氏阳性细菌（ ）均表现出直接抗菌活性。合成pH值（6 - 11）与AgHAp NPs的银含量（4.5 - 0.45 wt%）呈负相关，进而与抗菌效果相关，从而为目标应用提供了可调节的效果。AgHAp NPs比含银的银纳米颗粒具有更强的抗菌效果，并且对小鼠成纤维细胞L929细胞系的细胞毒性更小。因此，作为针对厌氧牙周细菌和好氧牙科细菌的有效、广谱、生物相容性抗菌剂，AgHAp NPs（尤其是AgHAp7）优于银纳米颗粒。AgHAp NPs的合成成本低且可扩展，这对于治疗全球大量受牙周炎和龋齿影响的贫困人口来说是重要因素。
