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

持续的COVID-19大流行导致关键医疗设备短缺，包括N95口罩。为节省资源及维持一定程度的防护，医务工作者已开始重复使用口罩。虽然紫外线杀菌辐照（UVGI）是一种在医疗环境中广泛使用的灭菌技术，已被证明可有效消毒面罩过滤器，但由于弹性体组件（如鼻泡沫和头带）的劣化，面罩制造商不建议使用该方法，因为该方法会妨碍灭菌后的有效配合。UVGI利用电磁光谱的深紫外部分的辐射，因为其被微生物核酸强烈吸收，这导致它们的降解。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，迫切需要开发耐UVGI辐射的弹性体材料，以实现N95口罩的去污和重复使用。如果相同的抗紫外线弹性体材料也具有固有的抗微生物特性，以进一步最大限度地减少COVID-19的传播，那将是更令人感兴趣的。已知水合氧化石墨烯同时具有这两种理想的属性-即在深紫外波长下的强光学吸收和经证实的抗微生物特性。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，而且适用于一般医疗用途，包括未来的大流行病。该项目正在合成基于水合氧化石墨烯（hGO）的弹性体复合材料，使N95口罩能够在COVID-19和未来的大流行病期间灭菌和重复使用。hGO不仅提供对紫外线杀菌照射（UVGI）照射的抗性，还赋予抗微生物性质。耐UVGI性是由于吸收UV光的聚合物添加剂为复合材料提供耐UV性的事实。在这种情况下，与所有石墨烯材料一样，由于hGO结构的共轭部分，hGO在深紫外波长下具有高吸收性。此外，已知hGO的高自由基含量会诱导脂质过氧化，破坏脂质膜的完整性，因此赋予几乎无处不在的抗微生物性质。由于包膜病毒（如COVID-19）也具有脂质膜，因此预期hGO在此背景下可有效作为抗病毒剂。为了评估UVGI对弹性体机械性能的影响，hGO复合材料在深UV暴露后进行拉伸和循环疲劳测试，以进行应力/应变测量和寿命耐久性。对照和深紫外辐照样品的电子顺磁共振光谱进一步量化了hGO赋予的自由基含量，从而深入了解深紫外暴露如何影响自由基产生和抗菌效率。通过改变hGO和/或相关化学官能化石墨烯材料的量，实现了耐用的弹性体复合材料，其中耐紫外线性、机械性能和抗微生物活性针对N95面罩灭菌和重复使用进行了优化。该奖项反映了NSF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.