Plasma-activated water (PAW) is a novel antimicrobial agent with negligible toxicity and environmental burden, holding promise as an alternative to chemical disinfectants and antibiotics. In practice, liquid disinfectants are often soaked with cotton materials before further use. Rich in reducing functional groups on the surface, cotton will inevitably react with PAW, leading to the deterioration of PAW’s functions. To resolve this issue, this work proposes a new concept of “secondary activation” for retaining and enhancing PAW’s bioactivity, i.e., pre-treating cotton with air plasma before soaking PAW. For the first time, we find that the PAW absorbed by raw cotton completely loses its bactericidal effect, while plasma-treated cotton (PTC) restores the disinfection capacity and prolongs its effective duration. This restoration is attributed to the absorption of plasma-generated reactive species by cotton with oxidizing and nitrifying modifications on the fiber surface. Consequently, the concentrations of aqueous species in PAW increase rather than decrease after absorption by PTC. In addition, the PTC after 28-day storage can still enable PAW to achieve a bacterial reduction of ∼3 logs. This work identifies and addresses a crucial limitation in the disinfection application of PAW and elucidates the mechanism underlying PTC production and secondary activation of PAW.

中文翻译：

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经等离子体处理的棉花对等离子体活化水的二次活化，以恢复和增强消毒效果


等离子体活化水 （PAW） 是一种新型抗菌剂，毒性和环境负担可以忽略不计，有望成为化学消毒剂和抗生素的替代品。在实践中，液体消毒剂通常在进一步使用之前用棉材料浸泡。棉花表面富含还原官能团，不可避免地会与 PAW 发生反应，导致 PAW 的功能恶化。为了解决这个问题，这项工作提出了一种新的 “二次活化 ”概念，用于保留和增强PAW的生物活性，即在浸泡PAW之前用空气等离子体对棉花进行预处理。我们首次发现，原棉吸收的 PAW 完全失去了杀菌作用，而等离子体处理棉 （PTC） 恢复了消毒能力并延长了其有效持续时间。这种恢复归因于棉花对等离子体产生的活性物质的吸收，并在纤维表面进行了氧化和硝化改性。因此，PAW 中水性物质的浓度在被 PTC 吸收后增加而不是减少。此外，储存 28 天后的 PTC 仍可使 PAW 实现 ∼3 个对数的细菌减少。这项工作确定并解决了 PAW 消毒应用中的关键限制，并阐明了 PTC 产生和 PAW 二次激活的机制。