Wardlaw Tia A, Masri Abdulkader, Brown David M, Johnston Helinor J
NanoSafety Research Group, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.
Nanomaterials (Basel). 2025 Jul 16;15(14):1103. doi: 10.3390/nano15141103.
Due to the growth in the application of antibacterial nanomaterials (NMs), there is an increased potential for ingestion by humans. Evidence shows that NMs can induce dysbiosis in the gut microbiota in vivo. However, in vitro investigation of the antibacterial activity of NMs on gut-relevant, commensal bacteria has been neglected, with studies predominantly assessing NM toxicity against pathogenic bacteria. The current study investigates the antibacterial activity of copper oxide (CuO) NMs to K12, , and using a combination of approaches and evaluates the importance of reactive oxygen species (ROS) production as a mechanism of toxicity. The impact of CuO NMs (100, 200, and 300 μg/mL) on the growth and viability of bacterial strains was assessed via plate counts, optical density (OD) measurements, well and disc diffusion assays, and live/dead fluorescent imaging. CuO NMs reduced the viability of all bacteria in a concentration-dependent manner in all assays except the diffusion assays. The most sensitive methods were OD measurements and plate counts. The sensitivity of bacterial strains varied depending on the method, but overall, the results suggest that K12 is the most sensitive to CuO NM toxicity. The production of ROS by all bacterial strains was observed via DCFH-DA fluorescent imaging following exposure to CuO NMs (300 μg/mL). Overall, the data suggests that CuO NMs have antibacterial activity against gut-relevant bacteria, with evidence that NM-mediated ROS production may contribute to reductions in bacterial viability. Our findings suggest that the use of a combination of assays provides a robust assessment of the antibacterial properties of ingested NMs, and in particular, it is recommended that plate counts and OD measurements be prioritised in the future when screening the antibacterial properties of NMs.
由于抗菌纳米材料（NMs）应用的增加，人类摄入的可能性也随之提高。有证据表明，纳米材料可在体内诱导肠道微生物群失调。然而，纳米材料对肠道相关共生细菌抗菌活性的体外研究却被忽视了，目前的研究主要评估纳米材料对病原菌的毒性。本研究采用多种方法研究了氧化铜（CuO）纳米材料对K12、 和 的抗菌活性，并评估了活性氧（ROS）产生作为毒性机制的重要性。通过平板计数、光密度（OD）测量、孔板和纸片扩散试验以及活/死荧光成像，评估了CuO纳米材料（100、200和300μg/mL）对细菌菌株生长和活力的影响。除扩散试验外，在所有试验中，CuO纳米材料均以浓度依赖的方式降低了所有细菌的活力。最敏感的方法是OD测量和平板计数。细菌菌株的敏感性因方法而异，但总体而言，结果表明K12对CuO纳米材料的毒性最敏感。在暴露于CuO纳米材料（300μg/mL）后，通过DCFH-DA荧光成像观察了所有细菌菌株ROS的产生。总体而言，数据表明CuO纳米材料对肠道相关细菌具有抗菌活性，有证据表明纳米材料介导的ROS产生可能导致细菌活力下降。我们的研究结果表明，使用多种试验组合可以对抗菌纳米材料的抗菌性能进行有力评估，特别是建议在未来筛选纳米材料的抗菌性能时，优先考虑平板计数和OD测量。
