Accurate assessment of nanomedicines’ antibacterial properties is pivotal for their effective use in both in vitro and in vivo settings. Conventional antibacterial activity assessment methods, involving bacterial coculture with compounds on agar plates, may not fully suit nanomedicines due to their susceptibility to alterations in physicochemical properties induced by biological fluids. Furthermore, these biological fluids might even enhance the bacterial growth. This study introduces a novel, rigorous, and reproducible methodology for evaluating nanomedicine antibacterial properties using cell culture media (i.e., DMEM-FBS10%). To assess the antibacterial activity of the nanoparticles in cell culture media, superparamagnetic iron oxide nanoparticles (SPIONs) were chosen as the model nanomedicine due to their clinical significance. A comparative analysis between the traditional and our proposed methods yielded contrasting outcomes, shedding light on the significant impact of biological fluids on nanoparticle antibacterial activities. While the conventional approach suggested the antibacterial effectiveness of SPIONs against Staphylococcus aureus, our innovative method unveiled a substantial increase in bacterial growth in the presence of biological fluids. More specifically, we found a significant increase in bacterial growth when exposed to bare SPIONs at various concentrations, while the formation of a protein corona on SPION surfaces could markedly reduce the observed bacterial growth compared to the control group. These findings underscore the necessity for more refined evaluation techniques that can better replicate the in vivo environment when studying the nanomedicine’s antibacterial capabilities.

中文翻译：

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评估生物液体中纳米药物抗菌特性的改进方法

准确评估纳米药物的抗菌特性对于其在体外和体内的有效使用至关重要。传统的抗菌活性评估方法，涉及细菌与琼脂平板上的化合物共培养，可能不完全适合纳米药物，因为它们容易受到生物体液引起的理化性质的改变。此外，这些生物液体甚至可能促进细菌生长。这项研究引入了一种新颖、严格且可重复的方法，用于使用细胞培养基（即DMEM-FBS10%）评估纳米药物的抗菌特性。为了评估纳米颗粒在细胞培养基中的抗菌活性，由于其临床意义，超顺磁性氧化铁纳米颗粒（SPION）被选为模型纳米药物。传统方法和我们提出的方法之间的比较分析产生了对比结果，揭示了生物体液对纳米颗粒抗菌活性的显着影响。虽然传统方法表明 SPION 对金黄色葡萄球菌具有抗菌功效，但我们的创新方法揭示了在生物液体存在下细菌生长的大幅增加。更具体地说，我们发现，当暴露于不同浓度的裸露 SPION 时，细菌生长显着增加，而与对照组相比，SPION 表面上蛋白电晕的形成可以显着减少观察到的细菌生长。这些发现强调了在研究纳米药物的抗菌能力时需要更精细的评估技术，以便更好地复制体内环境。