RAPID: Silver and Copper-based Nanowire Structures for Antiviral Applications

摘要：当前的COVID-19大流行已经确定了美国应对国家生物灾害战略准备中的关键问题。其中一个问题是N95呼吸器短缺，N95呼吸器为医护人员治疗感染患者提供关键保护。这个问题是这些N95口罩一次性使用的直接后果；聚合物纤维过滤器，包括N95和HEPA过滤器，捕获和积累活病原体，因此具有生物危害性。本文提出了金属纳米线燕窝和静电纺纤维作为解决这些问题的方法，从而改进了呼吸器。多孔金属纳米线鸟巢允许空气通过，类似于聚合物纤维过滤器，但金属表面具有抗菌和抗病毒的特性。因此，在鸟巢中捕获的病原体被灭活，提高了对医务工作者的保护，延长了呼吸器的使用寿命。同样的金属纳米线也将被集成到自由表面静电纺丝装置中，从而产生带有抗菌/抗病毒纳米线的毛茸茸的聚合物纤维。静电纺口罩可以在内部熔化并重新纺成新的口罩。这个回收步骤允许呼吸器不断重复使用，消除了不断补充库存的需要。这些努力共同解决了当前大流行中口罩短缺的问题，并提出了一种具有生物活性成分的优质过滤产品。技术摘要：本研究旨在为N95口罩开发可重复使用的生物活性过滤材料。目前的过滤材料是一次性的，会积累活的病原体，从本质上讲是不卫生的。我们建议用两种方法来应对这些问题。在第一种方法中，将使用银和铜纳米线制备冷冻铸造金属纳米线鸟巢。鸟巢的多孔结构允许空气通过，类似于传统的过滤器，而银和铜作为纳米粒子已被证明具有抗菌和抗病毒的特性。纳米线具有穿透细胞和病毒膜的能力，因此对病原体具有更高的功效。在第二种方法中，将制备静电纺聚丙烯纤维垫，作为传统空气吹制聚合物过滤器的替代品。这种电纺丝织物可以根据操作者的脸部定制，为其提供了一种特殊的密封，可以作为呼吸器使用。使用过的防护口罩可在现场熔化（熔化温度210-280℃）并重新纺丝，以制备新的卫生防护口罩。将纳米线掺入熔融的聚丙烯中，将产生具有细金属纳米线毛的聚合物纤维。和以前一样，金属纳米线将具有抗菌和抗病毒的特性。将使用细菌和噬菌体（感染细菌的病毒）的悬浮液和气溶胶快速测试鸟巢、静电纺过滤器和混合纺织品的功效。大肠杆菌和枯草芽孢杆菌将分别作为革兰氏阴性和革兰氏阳性细菌病原体的非致病性替代品。囊病毒科的包膜噬菌体将作为SARS-CoV-2的非致病性替代物。这项研究将研究纳米线作为抗菌和抗病毒药物的可行性，开发一种新的纳米结构过滤材料，并探索一种替代的制造方法，从而产生新的材料和技术，对美国应对生物灾害的准备产生直接影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Abstract: The current COVID-19 pandemic has identified key problems in the US strategic preparedness for a national biological disaster. One of those is a shortage of N95 respirators, which provide critical protection to medical personnel as they treat infected patients. This issue is a direct consequence of the one-time-use nature of these N95 respirators; polymer fiber filters, including N95 and HEPA filters, capture and accumulate live pathogens, and so become biohazardous. In the proposed work, metallic nanowire bird’s nests and electrospun fibers are presented as approaches to resolve these problems, resulting in an improved respirator. The porous metallic nanowire bird’s nests allow air to pass through, similar to a polymer fiber filter, but the metallic surfaces possess antibacterial and antiviral qualities. As a consequence, pathogens captured in the bird’s nest are inactivated, improving the protection to medical workers and prolonging the usefulness of the respirator. The same metallic nanowires will also be integrated into a free surface electrospinning device, resulting in polymer fibers which are hairy with the antibacterial/antiviral nanowires. Electrospun respirators can be melted down in-house and re-spun into new respirators. This recycling step allows for respirators to be continuously re-used, removing the need to constantly re-stock. These efforts together may resolve the shortages of respirators in the current pandemic and present a superior filter product with bioactive components. Technical Abstract: This work seeks to develop reusable, bioactive filter materials for N95 respirators. Current filter materials are one-time-use and accumulate live pathogens, making them intrinsically unsanitary. We propose to respond to these problems using two approaches. In the first approach, freeze-cast metallic nanowire bird’s nests will be prepared using Ag and Cu nanowires. The porous structure of the bird’s nest allows air to pass, similar to a traditional filter, while Ag and Cu have been shown to have antibacterial and antiviral qualities as nanoparticles. Nanowires may present higher efficacy against pathogens due to their ability to puncture the cell and viral membranes. In the second approach, electrospun polypropylene fiber mats will be prepared as an alternative to traditional air-blown polymer filters. The electrospun textiles can be grown to custom fit operator’s faces providing an exceptional seal for use as a respirator. Used respirators can be melted on-site (melting temperature 210-280 °C) and re-spun, to prepare new, sanitary respirators. Incorporating nanowires into the molten polypropylene will result in polymer fibers with fine metallic nanowire hairs. As before, the metallic nanowires will confer antibacterial and antiviral qualities. The efficacy of the bird’s nest, the electrospun filter, and hybrid textile will be rapidly tested using suspensions and aerosols of bacteria and bacteriophages (viruses that infect bacteria). Escherichia coli and Bacillus subtilis will serve as non-pathogenic surrogates for Gram-negative and Gram-positive bacterial pathogens, respectively. An enveloped bacteriophage in family Cystoviridae will serve as a non-pathogenic surrogate of SARS-CoV-2. The proposed research will investigate the feasibility of nanowires as antibacterial and antiviral agents, develop a new, nanostructured filter material, and explore an alternative fabrication methodology, resulting in new materials and techniques with direct consequences to the US preparedness for biological disasters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.