Purpose: Selenium nanoparticles (Se NPs) are promising antibacterial agents to tackle the growing problem of antimicrobial resistance. The aim of this study was to fabricate Se NPs with a net positive charge to enhance their antibacterial efficacy.
Methods: Se NPs were coated with a positively charged protein – recombinant spider silk protein eADF4(κ 16) – to give them a net positive surface charge. Their cytotoxicity and antibacterial activity were investigated, with negatively charged polyvinyl alcohol coated Se NPs as a control. Besides, these eADF4(κ 16)-coated Se NPs were immobilized on the spider silk films, and the antibacterial activity of these films was investigated.
Results: Compared to the negatively charged polyvinyl alcohol coated Se NPs, the positively charged eADF4(κ 16)-coated Se NPs demonstrated a much higher bactericidal efficacy against the Gram-negative bacteria E. coli, with a minimum bactericidal concentration (MBC) approximately 50 times lower than that of negatively charged Se NPs. Cytotoxicity testing showed that the eADF4(κ 16)-coated Se NPs are safe to both Balb/3T3 mouse embryo fibroblasts and HaCaT human skin keratinocytes up to 31 μg/mL, which is much higher than the MBC of these particles against E. coli (8 ± 1 μg/mL). In addition, antibacterial coatings were created by immobilising the eADF4(κ 16)-coated Se NPs on positively charged spider silk films and these were shown to retain good bactericidal efficacy and overcome the issue of low particle stability in culture broth. It was found that these Se NPs needed to be released from the film surface in order to exert their antibacterial effects and this release can be regulated by the surface charge of the film, such as the change of the spider silk protein used.
Conclusion: Overall, eADF4(κ 16)-coated Se NPs are promising new antibacterial agents against life-threatening bacteria.

Keywords: Gram-positive, Gram-negative, E. coli, antibacterial film, cytotoxicity


中文翻译：

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重组蜘蛛丝蛋白 eADF4(κ16) 包被硒纳米粒子增强抗菌活性。


目的：硒纳米粒子（Se NP）是一种很有前途的抗菌剂，可以解决日益严重的抗菌素耐药性问题。本研究的目的是制造带有净正电荷的硒纳米粒子，以增强其抗菌功效。

方法： Se NPs 涂有带正电荷的蛋白质 - 重组蜘蛛丝蛋白 eADF4（κ 16） - 赋予它们表面净正电荷。研究了它们的细胞毒性和抗菌活性，并以带负电荷的聚乙烯醇包被的 Se NPs 作为对照。此外，将这些eADF4(κ 16)包被的Se NPs固定在蜘蛛丝膜上，并研究了这些膜的抗菌活性。

结果：与带负电的聚乙烯醇包覆的Se NPs相比，带正电的eADF4(κ 16)包覆的Se NPs对革兰氏阴性菌大肠杆菌具有更高的杀菌效果，其最低杀菌浓度(MBC)约为比带负电的 Se NPs 低 50 倍。细胞毒性测试表明，eADF4(κ 16) 包被的 Se NPs 对 Balb/3T3 小鼠胚胎成纤维细胞和 HaCaT 人皮肤角质形成细胞均安全，浓度高达 31 μg/mL，远高于这些颗粒对大肠杆菌的 MBC (8±1微克/毫升)。此外，通过将 eADF4(κ 16) 包被的 Se NP 固定在带正电的蜘蛛丝膜上来创建抗菌涂层，这些涂层被证明保留了良好的杀菌功效，并克服了培养液中颗粒稳定性低的问题。研究发现，这些Se NPs需要从薄膜表面释放才能发挥其抗菌作用，并且这种释放可以通过薄膜的表面电荷来调节，例如所用蜘蛛丝蛋白的变化。

结论：总体而言，eADF4(κ 16) 包被的 Se NP 是对抗危及生命的细菌的有希望的新型抗菌剂。


关键词：革兰氏阳性、革兰氏阴性、大肠杆菌、抗菌膜、细胞毒性