RAPID: Hydrated Graphene Oxide Elastomeric Composites for Sterilizable and Reusable N95 Masks

持续的COVID-19大流行导致N95口罩等关键医疗设备短缺。为了节约资源并保持对COVID-19的一定程度的保护，医务工作者已经开始重复使用口罩。虽然紫外线杀菌照射（UVGI）是一种在医疗环境中广泛使用的消毒技术，已被证明对口罩过滤器消毒有效，但口罩制造商不建议使用这种方法，因为鼻泡沫和头带等弹性成分会变质，在消毒后无法有效贴合。UVGI利用电磁波谱中深紫外部分的辐射，因为它被微生物核酸强烈吸收，导致其降解。然而，目前使用的弹性体材料在这些深紫外波长下同样受到损害。因此，开发抗UVGI辐射的弹性材料，使N95口罩能够去污和重复使用，具有很高的紧迫性。如果同样的抗紫外线弹性体材料也具有固有的抗菌特性，以进一步减少COVID-19的传播，那将是更大的兴趣。已知水合氧化石墨烯同时具有这两种理想的特性，即在深紫外波长下具有强光学吸收和经过验证的抗菌特性。因此，该项目旨在快速开发基于水合氧化石墨烯的弹性体复合材料，以实现N95口罩的灭菌和重复使用。重要的是，这项研究的成果不仅解决了当前的COVID-19危机，而且适用于包括未来大流行在内的一般医疗用途。该项目正在合成基于水合氧化石墨烯（hGO）的弹性复合材料，以实现N95口罩在COVID-19和未来大流行期间的消毒和重复使用。氧化石墨烯不仅具有抗紫外线杀菌照射（UVGI）的能力，还具有抗菌性能。抗UVGI性能源于这样一个事实，即吸收紫外线的聚合物添加剂为复合材料提供了抗紫外线性能。在这种情况下，像所有石墨烯材料一样，由于氧化石墨烯结构的共轭部分，氧化石墨烯在深紫外波长处具有很高的吸收性。此外，已知高自由基含量的氧化石墨烯会诱导脂质过氧化，破坏脂质膜的完整性，从而赋予几乎无处不在的抗菌特性。由于像COVID-19这样的包膜病毒也具有脂质膜，因此在这种情况下，hGO有望成为有效的抗病毒药物。为了评估UVGI对弹性力学性能的影响，在深紫外线照射后，对hGO复合材料进行了拉伸和循环疲劳测试，以测量应力/应变和寿命耐久性。对照和深紫外照射样品的电子顺磁共振波谱进一步量化了氧化石墨烯传递的自由基含量，从而深入了解深紫外照射如何影响自由基产生和抗菌效率。通过改变氧化石墨烯和/或相关的化学功能化石墨烯材料的用量，一种耐用的弹性复合材料正在实现，这种复合材料的抗紫外线、机械性能和抗菌活性都得到了优化，可用于N95口罩的灭菌和重复使用。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。

The ongoing COVID-19 pandemic has led to a shortage of critical medical equipment, including N95 masks. In order to conserve resources and maintain some level of protection against COVID-19, medical workers have begun reusing masks. While ultraviolet germicidal irradiation (UVGI), a widely used sterilization technique in medical settings, has been shown to be effective at disinfecting mask filters, it is not recommended by mask manufacturers due to deterioration of elastomeric components such as the nose foam and head straps that prevents an effective fit following sterilization. UVGI utilizes radiation in the deep-UV portion of the electromagnetic spectrum due to its strong absorption by microbial nucleic acids, which leads to their degradation. However, currently used elastomeric materials are similarly compromised at these deep-UV wavelengths. Therefore, it is of high urgency to develop elastomeric materials that are resistant to UVGI irradiation to enable decontamination and reuse of N95 masks. It would be of even greater interest if the same UV-resistant elastomeric materials also possessed intrinsic antimicrobial properties to further minimize the spread of COVID-19. Hydrated graphene oxide is known to possess both of these desirable attributes concurrently – namely, strong optical absorption at deep-UV wavelengths and proven antimicrobial properties. This project thus aims to rapidly develop elastomeric composites based on hydrated graphene oxide in order to enable the sterilization and reuse of N95 masks. Importantly, the outcomes of this research not only address the current COVID-19 crisis, but are applicable for general medical use including future pandemics.This project is synthesizing elastomeric composites based on hydrated graphene oxide (hGO) to enable N95 mask sterilization and reuse during COVID-19 and future pandemics. Not only does hGO provide resistance to ultraviolet germicidal irradiation (UVGI) irradiation, it also imparts antimicrobial properties. UVGI resistance results from the fact that polymeric additives that absorb UV light provide UV resistance to the composite. In this case, like all graphene materials, hGO is highly absorbing at deep-UV wavelengths due to the conjugated portions of the hGO structure. In addition, the high radical content of hGO is known to induce lipid peroxidation, destroying the integrity of lipid membranes and hence imparting nearly ubiquitous antimicrobial properties. Since enveloped viruses like COVID-19 also possesses lipid membranes, hGO is expected to be effective as an antiviral agent in this context. To assess the effect of UVGI on elastomeric mechanical properties, the hGO composites are subjected to tensile and cyclic fatigue testing following deep-UV exposure for stress/strain measurements and lifetime durability. Electron paramagnetic resonance spectroscopy on control and deep-UV irradiated samples further quantify the radical content imparted by hGO, thus providing insight into how deep-UV exposure affects radical production and antimicrobial efficiency. By varying the amount of hGO and/or related chemically functionalized graphene materials, a durable elastomeric composite is being realized in which the UV resistance, mechanical properties, and antimicrobial activity are optimized for N95 mask sterilization and reuse.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.