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

持续的新冠肺炎大流行导致包括N95口罩在内的关键医疗设备短缺。为了节约资源并保持对新冠肺炎的一定程度的防护，医务人员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，已被证明在消毒口罩过滤器方面是有效的，但口罩制造商并不推荐使用紫外线杀菌照射，因为橡胶部件，如鼻泡和头带，在灭菌后无法有效配合。UVGI利用电磁光谱中的深紫外线部分的辐射，因为它被微生物核酸强烈吸收，从而导致它们的降解。然而，目前使用的弹性材料在这些深紫外光波长下也同样受到影响。因此，当务之急是开发耐UVGI辐射的弹性材料，使N95面具能够去污和重复使用。如果同样的抗紫外线弹性体材料也具有内在的抗菌性能，进一步减少新冠肺炎的传播，人们将会更感兴趣。众所周知，水合氧化石墨烯同时具有这两个理想的特性--即在深紫外光波长下的强光吸收和公认的抗菌性能。因此，该项目旨在快速开发基于水合氧化石墨烯的弹性复合材料，以便能够对N95面具进行灭菌和重复使用。重要的是，这项研究的成果不仅针对当前的新冠肺炎危机，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的弹性体复合材料，以使N95口罩能够在新冠肺炎和未来大流行期间杀菌和重复使用。HGO不仅对紫外线杀菌辐射(UVGI)具有抵抗力，还具有抗菌性能。抗UVGI的原因是吸收紫外线的聚合物添加剂为复合材料提供了抗紫外线的性能。在这种情况下，像所有的石墨烯材料一样，由于hGO结构的共轭部分，hGO在深紫外光波长具有高度的吸收。此外，已知hGO的高自由基含量会导致脂质过氧化，破坏脂膜的完整性，从而赋予几乎无处不在的抗菌特性。由于新冠肺炎等被包裹的病毒也有脂膜，因此hGO有望在这方面作为一种有效的抗病毒药物。为了评估UVGI对弹性力学性能的影响，在深紫外光照射后，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。对照和深紫外光照射的样品的电子顺磁共振波谱进一步量化了hGO提供的自由基含量，从而深入了解深紫外光照射如何影响自由基的产生和抗菌效率。通过改变hGO和/或相关的化学功能化石墨烯材料的量，正在实现一种耐用的弹性复合材料，其中耐紫外线、机械性能和抗菌活性针对N95面具的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。

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.