Objective

Cobalt nanoparticles (NPs) when released into the air during industrial processes, can enter the lungs through inhalation, leading to potential toxicity and respiratory issues. The mechanism of cobalt toxicity is not well understood and needs further investigation.

Methods

We, therefore, studied the effects of two kinds of cobalt-based nanoparticles (NPs) on lung cells. These NPs were Co NPs (i.e. Cobalt NPs) and Co-Fe NPs (i.e. CoFe₂O₄ NPs) that were similar in size and shape but slightly differed for the surface iron composition. The average size of Co NPs was 28 ± 18 nm, and that of Co-Fe was 26 ± 13 nm. We exposed the cells to the NPs for 24 h and measured their viability by MTT assay and CalceinAM fluorescence imaging. Potential induction of reactive oxygen species (ROS) was detected by probes DHE specific for superoxide (O₂^•–) and DCFH-DA for hydrogen peroxide (H₂O₂). Antioxidant glutathione (GSH) quantification was followed by measuring apoptotic/necrotic potential.

Results

Using Co NPs and Co-Fe NPs, we measured the IC50 for cell growth in A549 cells after 24 h of exposure. The values were 79 μg/mL and 163 μg/mL, respectively. We also observed that both NPs induced ROS and reduced the fluorescence of CalceinAM in the cells, but Co NPs had a stronger effect than Co-Fe NPs. This was correlated with the production of O₂^– by the NPs, which was higher for Co NPs than for Co-Fe NPs. On the other hand, H₂O₂ production was higher for Co-Fe NPs than for Co NPs. Our study suggests that the main cause of differential O₂^– production is the differential release Co²⁺ ion due to surface modification resulting in differential quenching of green (CalceinAM) fluorescence by both NPs. Both NPs induced apoptosis mode of cell death.

Conclusion

Our data from the use of naïve and surface-modified cobalt-based NPs, suggest that NAC can protect cells from cobalt-based NP toxicity by not only restoring cellular GSH levels but also by chelating released Co²⁺ ions from the NPs surfaces. Additionally, this study for the first time to our knowledge indicates that CalceinAM alone is not sufficient to assess the toxicity of cobalt-based NPs. Other methods should be used to confirm the cytotoxicity data of cobalt-based NPs.

中文翻译：

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钴基纳米粒子强烈减弱 CalceinAM 荧光，与其在人肺细胞系中的细胞毒性潜力无关

客观的

钴纳米颗粒 (NP) 在工业生产过程中释放到空气中时，会通过吸入进入肺部，导致潜在的毒性和呼吸系统问题。钴毒性的机制尚不清楚，需要进一步研究。

方法

因此，我们研究了两种钴基纳米粒子（NP）对肺细胞的影响。这些NP是Co NP（即钴NP）和Co-Fe NP（即CoFe ₂ O ₄ NP），其尺寸和形状相似，但表面铁成分略有不同。Co NPs 的平均尺寸为 28 ± 18 nm，Co-Fe 的平均尺寸为 26 ± 13 nm。我们将细胞暴露于 NP 24 小时，并通过 MTT 测定和 CalceinAM 荧光成像测量其活力。通过针对超氧化物 (O ₂ ^•– ) 的探针 DHE 和针对过氧化氢 (H ₂ O ₂ ) 的 DCFH-DA 检测潜在的活性氧 (ROS) 诱导。抗氧化剂谷胱甘肽（GSH）定量后测量细胞凋亡/坏死潜力。

结果

使用 Co NP 和 Co-Fe NP，我们测量了 A549 细胞暴露 24 小时后细胞生长的 IC50。值分别为 79 μg/mL 和 163 μg/mL。我们还观察到两种纳米颗粒都能诱导 ROS 并降低细胞中 CalceinAM 的荧光，但 Co NPs 的效果比 Co-Fe NPs 更强。_{这与 NP 产生的 O 2} ^-相关，Co NP 的 O 2 - 产量高于 Co-Fe NP。另一方面，Co-Fe NP 的 H ₂ O ₂产量高于 Co NP。_{我们的研究表明，O 2} ^-产生差异的主要原因是由于表面改性导致两种纳米颗粒对绿色（CalceinAM）荧光的差异猝灭而导致Co ²⁺离子的差异释放。两种纳米粒子均诱导细胞死亡的凋亡模式。

结论

我们使用天然和表面改性的钴基纳米粒子的数据表明，NAC 不仅可以恢复细胞的 GSH 水平，还可以螯合纳米粒子表面释放的 Co 2+ 离子，从而保护细胞免受钴基纳米粒子的毒性^。此外，据我们所知，这项研究首次表明仅使用 CalceinAM 不足以评估钴基纳米颗粒的毒性。应使用其他方法来确认钴基纳米颗粒的细胞毒性数据。