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.
