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

非技术摘要：当前的新冠肺炎大流行已经确定了美国应对国家生物灾难的战略准备中的关键问题。其中之一是N95呼吸器短缺，这种口罩在治疗感染患者时为医务人员提供关键保护。这个问题是这些N95呼吸器一次性使用的直接后果；包括N95和HEPA过滤器在内的聚合物纤维过滤器捕获并积累活的病原体，因此成为生物危险。在拟议的工作中，提出了金属纳米线燕窝和电纺纤维作为解决这些问题的方法，从而改进了呼吸器。这种多孔的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，在燕窝中捕获的病原体被灭活，提高了对医务人员的保护，并延长了呼吸器的用途。同样的金属纳米线也将被集成到自由表面静电纺丝设备中，从而产生带有抗菌/抗病毒纳米线的聚合物纤维。电纺口罩可以在内部熔化，然后重新纺制成新的口罩。这一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。这些共同努力可能会解决当前大流行中呼吸防护口罩的短缺问题，并提供含有生物活性成分的优质过滤产品。技术摘要：这项工作旨在为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使用的，会积累活的病原体，使其本质上不卫生。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来制备冷冻铸造的金属纳米线燕窝。燕窝的多孔结构允许空气通过，类似于传统的过滤器，而银和铜已被证明具有纳米颗粒的抗菌和抗病毒特性。纳米线可能会对病原体表现出更高的疗效，因为它们能够穿透细胞和病毒膜。在第二种方法中，将制备电纺聚丙烯纤维垫，以替代传统的吹风聚合物过滤器。这种电纺纺织品可以生长到适合操作员的脸部，提供了用作呼吸器的特殊密封性。使用过的口罩可以现场熔化(熔化温度210-280°C)并重新纺丝，以制备新的卫生口罩。在熔融的聚丙烯中加入纳米线将产生具有精细金属纳米线毛发的聚合物纤维。和以前一样，金属纳米线将提供抗菌和抗病毒的品质。将使用细菌和噬菌体(感染细菌的病毒)的悬浮液和气雾剂来快速测试燕窝、静电纺丝过滤器和混合纺织品的有效性。大肠埃希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的非致病性替代品。这项拟议的研究将调查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，并探索一种替代制造方法，从而产生对美国应对生物灾难的准备有直接影响的新材料和技术。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.