Integrated photothermal decontamination device for N95 respirators

Antimicrobial and Antifouling Effects of Petal-Like Nanostructure by Evaporation-Induced Self-Assembly for Personal Protective Equipment

Although the personal protective equipment (PPE) used by healthcare workers (HCWs) effectively blocks hazardous substances and pathogens, it does not fully rule out the possibility of infection, as pathogens surviving on the fabric surface pose a substantial risk of cross-infection through unintended means. Therefore, PPE materials that exhibit effective biocidal activity while minimizing contamination by viscous body fluids (e.g., blood and saliva) and pathogen-laden droplets are highly sought. In this study, petal-like nanostructures (PNSs) are synthesized through the vertical rearrangement of colloidal lamellar bilayers via evaporation-induced self-assembly of octadecylamine, silica-alumina sol, and diverse photosensitizer. The developed method is compatible with various fabrics and imparts visible-light-activated antimicrobial and superhydrophobic-based antifouling activities. PNS-coated fabrics could provide a high level of protection and effectively block pathogen transmission as exemplified by their ability to roll off viscous body fluids reducing bacterial droplet adhesion and to inactivate various microorganisms. The combination of antifouling and photobiocidal activities results in the complete inactivation of sprayed pathogen-laden droplets within 30 min. Thus, this study paves the way for effective contagious disease management and the protection of HCWs in general medical environments, inspiring further research on the fabrication of materials that integrate multiple useful functionalities.

Disinfection and decontamination in the context of SARS-CoV-2-specific data

Given the high transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as witnessed early in the coronavirus disease 2019 (COVID-19) pandemic, concerns arose with the existing methods for virus disinfection and decontamination. The need for SARS-CoV-2-specific data stimulated considerable research in this regard. Overall, SARS-CoV-2 is practically and equally susceptible to approaches for disinfection and decontamination that have been previously found for other human or animal coronaviruses. The latter have included techniques utilizing temperature modulation, pH extremes, irradiation, and chemical treatments. These physicochemical methods are a necessary adjunct to other prevention strategies, given the environmental and patient surface ubiquity of the virus. Classic studies of disinfection have also allowed for extrapolation to the eradication of the virus on human mucosal surfaces by some chemical means. Despite considerable laboratory study, practical field assessments are generally lacking and need to be encouraged to confirm the correlation of interventions with viral eradication and infection prevention. Transparency in the constitution and use of any method or chemical is also essential to furthering practical applications.

Ultraviolet-C Irradiation, Heat, and Storage as Potential Methods of Inactivating SARS-CoV-2 and Bacterial Pathogens on Filtering Facepiece Respirators

The arrival of SARS-CoV-2 to Aotearoa/New Zealand in February 2020 triggered a massive response at multiple levels. Procurement and sustainability of medical supplies to hospitals and clinics during the then upcoming COVID-19 pandemic was one of the top priorities. Continuing access to new personal protective equipment (PPE) was not guaranteed; thus, disinfecting and reusing PPE was considered as a potential alternative. Here, we describe part of a local program intended to test and implement a system to disinfect PPE for potential reuse in New Zealand. We used filtering facepiece respirator (FFR) coupons inoculated with SARS-CoV-2 or clinically relevant multidrug-resistant pathogens (Acinetobacter baumannii Ab5075, methicillin-resistant Staphylococcus aureus USA300 LAC and cystic-fibrosis isolate Pseudomonas aeruginosa LESB58), to evaluate the potential use of ultraviolet-C germicidal irradiation (UV-C) or dry heat treatment to disinfect PPE. An applied UV-C dose of 1000 mJ/cm2 was sufficient to completely inactivate high doses of SARS-CoV-2; however, irregularities in the FFR coupons hindered the efficacy of UV-C to fully inactivate the virus, even at higher UV-C doses (2000 mJ/cm2). Conversely, incubating contaminated FFR coupons at 65 °C for 30 min or 70 °C for 15 min, was sufficient to block SARS-CoV-2 replication, even in the presence of mucin or a soil load (mimicking salivary or respiratory secretions, respectively). Dry heat (90 min at 75 °C to 80 °C) effectively killed 106 planktonic bacteria; however, even extending the incubation time up to two hours at 80 °C did not completely kill bacteria when grown in colony biofilms. Importantly, we also showed that FFR material can harbor replication-competent SARS-CoV-2 for up to 35 days at room temperature in the presence of a soil load. We are currently using these findings to optimize and establish a robust process for decontaminating, reusing, and reducing wastage of PPE in New Zealand.

Mapping of UV-C dose and SARS-CoV-2 viral inactivation across N95 respirators during decontamination

During public health crises like the COVID-19 pandemic, ultraviolet-C (UV-C) decontamination of N95 respirators for emergency reuse has been implemented to mitigate shortages. Pathogen photoinactivation efficacy depends critically on UV-C dose, which is distance- and angle-dependent and thus varies substantially across N95 surfaces within a decontamination system. Due to nonuniform and system-dependent UV-C dose distributions, characterizing UV-C dose and resulting pathogen inactivation with sufficient spatial resolution on-N95 is key to designing and validating UV-C decontamination protocols. However, robust quantification of UV-C dose across N95 facepieces presents challenges, as few UV-C measurement tools have sufficient (1) small, flexible form factor, and (2) angular response. To address this gap, we combine optical modeling and quantitative photochromic indicator (PCI) dosimetry with viral inactivation assays to generate high-resolution maps of "on-N95" UV-C dose and concomitant SARS-CoV-2 viral inactivation across N95 facepieces within a commercial decontamination chamber. Using modeling to rapidly identify on-N95 locations of interest, in-situ measurements report a 17.4 ± 5.0-fold dose difference across N95 facepieces in the chamber, yielding 2.9 ± 0.2-log variation in SARS-CoV-2 inactivation. UV-C dose at several on-N95 locations was lower than the lowest-dose locations on the chamber floor, highlighting the importance of on-N95 dose validation. Overall, we integrate optical simulation with in-situ PCI dosimetry to relate UV-C dose and viral inactivation at specific on-N95 locations, establishing a versatile approach to characterize UV-C photoinactivation of pathogens contaminating complex substrates such as N95s.

Riboflavin Surface Modification of Poly(vinyl chloride) for Light-Triggered Control of Bacterial Biofilm and Virus Inactivation

Poly(vinyl chloride) (PVC) is the most used biomedical polymer worldwide. PVC is a stable and chemically inert polymer. However, microorganisms can colonize PVC producing biomedical device-associated infections. While surface modifications of PVC can help improve the antimicrobial and antiviral properties, the chemically inert nature of PVC makes those modifications challenging and potentially toxic. In this work, we modified the PVC surface using a derivative riboflavin molecule that was chemically tethered to a plasma-treated PVC surface. Upon a low dosage of blue light, the riboflavin tethered to the PVC surface became photochemically activated, allowing for Pseudomonas aeruginosa bacterial biofilm and lentiviral in situ eradication.

Ultraviolet-C as a Viable Reprocessing Method for Disposable Masks and Filtering Facepiece Respirators

In normal conditions, discarding single-use personal protective equipment after use is the rule for its users due to the possibility of being infected, particularly for masks and filtering facepiece respirators. When the demand for these protective tools is not satisfied by the companies supplying them, a scenario of shortages occurs, and new strategies must arise. One possible approach regards the disinfection of these pieces of equipment, but there are multiple methods. Analyzing these methods, Ultraviolet-C (UV-C) becomes an exciting option, given its germicidal capability. This paper aims to describe the state-of-the-art for UV-C sterilization in masks and filtering facepiece respirators. To achieve this goal, we adopted a systematic literature review in multiple databases added to a snowball method to make our sample as robust as possible and encompass a more significant number of studies. We found that UV-C's germicidal capability is just as good as other sterilization methods. Combining this characteristic with other advantages makes UV-C sterilization desirable compared to other methods, despite its possible disadvantages.