aPDI Method Proven Effective Against Norovirus, Coronaviruses, and Ebola, Lassa, and Nipah Viruses, according to WHO and Global Researchers, Including Singletto Co-Founders
The American Journal of Infection Control (August 2022) has published multiple studies, including peer-reviewed research from Singletto’s Lendvay, Chen, Clark, Mores, et al., confirming the antimicrobial efficacy of Antimicrobial Photodynamic Inactivation (aPDI) against many biological threats of global concern, including norovirus, coronaviruses, and Ebola, Lassa, and Nipah viruses.
The aPDI method relies on light-activated protective dyes (PDs), such as Methylene Blue (MB), to induce an antimicrobial effect. Researchers, collaborating with the World Health Organization (WHO) Global Research Forum, have spent two years studying the innovative technology as 1) a decontamination method for masks and other PPE and 2) a mask and PPE pre-treatment method for ongoing pathogen inactivation.
In 2020, the WHO-led DeMaND (Development of Methods for Mask and N95 Decontamination) study demonstrated the aPDI method “robustly and consistently” inactivated SARS-CoV-2 and other coronaviruses on the surfaces of commonly worn healthcare and community masks without sacrificing mask fit or integrity. This method, first suggested by Singletto Co-Founder Dr. James Chen, offered an important decontamination solution for those forced to re-use or extend their masks in times of crisis. Further, masks and respirators pre-treated with the protective dye Methylene Blue provided ongoing inactivation of coronavirus. Per Lendvay et al., 2021 (published in Infection Control and Hospital Epidemiology):
“Pre-treatment of masks with MB could provide a novel means of continual decontamination reducing exposure to SARS-CoV-2 … [and] of continual inactivation of viral particles to decontaminate a mask while donned [i.e., worn].”
Now, in an extensive collection of peer-reviewed research on this novel application of aPDI, researchers have further demonstrated the efficacy of light-activated Methylene Blue in 1) immediate decontamination and 2) ongoing antimicrobial efficacy situations.
Together with the WHO Global Research Forum – which was formed to foster research and innovation in Infection Prevention & Control (IPC) – researchers successfully harnessed aPDI technology against a wide variety of biological threats, including norovirus, coronaviruses, Ebola virus, Lassa virus, and Nipah virus (August 2022):
aPDI Method Inactivates 99.9% of SARS-CoV-2 on Community and Surgical Masks
Kabra, along with Singletto’s Lendvay, Chen, Rolley, and Mores, and Revolution-Zero (U.K. sustainable mask manufacturer) CEO Dawson, demonstrated that masks pretreated with protective dyes, including Methylene Blue and Riboflavin, can inactivate SARS-CoV-2 on masks. Researchers treated masks with varying concentrations of Methylene Blue and/or Riboflavin and measured efficacy after 0, 5, and 30 minutes of virus exposure in ~700 lux light. The authors found MB pre-treatment leads to 99.9% inactivation of SARS-CoV-2 on both clinically used disposable surgical masks and publicly available reusable masks. Low concentration MB inactivated 99.9% of SARS-CoV-2 on surgical masks in five minutes of ambient light (~700 lux). Increased concentrations of a combined MB and Riboflavin formulation inactivated 99.9% of SARS-CoV-2 on surgical masks in less than five minutes. Depending on the concentration of MB, the pre-treated sustainable and reusable Revolution-Zero masks inactivated 99.9% of SARS-CoV-2 in either five minutes or 30 minutes in ambient light. The authors note the simplicity and effectiveness MB formulations in particular make them “ideal for mask pre-treatment,” with the “potential for enhanced protection from this virus during MB use.”
Read More: https://doi.org/10.1016/j.ajic.2022.03.015
Authors: Kareem Kabra, George Washington University; Thomas Lendvay, Singletto; James Chen, Singletto; Paul Rolley, Singletto; Tom Dawson, Revolution-ZERO; Christopher Mores, George Washington University
aPDI Method Inactivates Coronaviruses and Ebola, Lassa, and Nipah Viruses on Respirators; MB Pre-Treatment Can Provide 21 Days of Ongoing Protection
Scholte et al. demonstrated MB’s efficacy as both a pre-treatment and decontamination method for N95 and KN95 respirators. The aPDI method was shown to inactivate multiple public health threats, including coronaviruses and Ebola, Lassa, and Nipah viruses on respirators. The researchers first tested the ability of MB to decontaminate masks inoculated with virus, and found that varied concentrations of MB successfully inactivated all viruses under bright (~50k lux) lighting conditions. Next, N95 and K95 respirators were pre-treated with one of several different concentrations of MB and measured for aPDI efficacy after 30 minutes of virus exposure in dark, ambient (~700 lux), or bright (~50k lux) lighting conditions. MB in higher concentrations completely inactivated the Ebola, Lassa, and Nipah viruses in 30 minutes of bright light. These higher MB concentrations also readily inactivated the Ebola and Lassa viruses in ambient light (~700 lux) on K95s. Researchers stated, “… pre-treatment may represent a promising strategy for adding an extra layer of protection to this type of PPE.” Further, in both the dark and ambient lighting conditions, MB inactivated all three SARS-CoV-2 strains (pre-Alpha, Beta, and Delta variants) and MERS-CoV. The researchers also exposed pre-treated respirators to up 252 hours of ambient light (mimicking 7-21 days of 12-hour dark and/or light cycles) and noted no change in efficacy against coronavirus strains. Per the authors, this suggests the MB pre-treatment method has potential to provide “robust and long-lasting protection against coronaviruses.”
Read More: https://doi.org/10.1016/j.ajic.2022.02.016
Authors: Florine Scholte, CDC; Kareem Kabra, George Washington University; Sarah Tritsch, George Washington University; Joel Montgomery, CDC; Christina Spiropoulou, CDC; Christopher Mores, George Washington University; Brian Harcourt, CDC
aPDI Method Decontaminates Norovirus from Surgical Masks
Wielick et al., including Singletto’s Lendvay, demonstrated that norovirus-inoculated surgical masks could be successfully decontaminated when treated with varying MB concentrations and exposed to 12,500-lux red light for 30 minutes. According to the authors, the small, nonenveloped human norovirus is notorious for its tenacity in the face of decontamination and “may be considered the gold standard for validating viral inactivation.” The harder-to-kill norovirus required MB concentrations 10-fold higher than those needed for coronavirus decontamination, yet these concentrations were still below that administered in clinical settings, per the authors, and caused rapid drops in viral levels in as little as 15 minutes. Notably, these findings can predict the inactivation of less resistant viruses, and “the protocol developed here thus solidifies the position of MB decontamination as an important tool in the package of practical pandemic preparedness.”
Read more: https://doi.org/10.1016/j.ajic.2022.01.024
Authors: Constance Wielick, Liège University; Allyson Fries, Liège University; Lorène Dams, Liège University; Ravo Razafimahefa, Liège University; Belinda Heyne, University of Calgary; Brian Harcourt, CDC; Thomas Lendvay, University of Washington; Jean-François Willaert, University of Liège; Simon de Jaeger, University of Liège; Eric Haubruge, University of Liège; Etienne Thiry, ULiège; Louisa Ludwig-Begall, Liège University
aPDI Pre-Treatment Method Inactivates Coronaviruses in 5 Minutes of Sunlight
Vos, Gordon, and Heyne demonstrated that low concentrations of MB pre-treated on surgical masks can completely inactivate the A59 strain Murine Hepatitis Virus (MHV) when exposed to only five minutes of sunlight. Researchers pre-treated surgical masks with low concentrations of MB, allowed them to dry overnight, inoculated the coupons with virus, and exposed them to simulated sunlight. Compared to untreated masks, which required several hours of simulated sunlight to display antiviral activity, the MB-treated masks achieved complete viral inactivation within 5 minutes. Additionally, in the absence of light, researchers observed a small reduction of viral titers amongst samples treated with MB, which was attributed to the antiviral activity of MB itself. The authors stated the study validates the “use of Methylene Blue in a combination of sunlight, as a robust decontamination method for PPE, such as surgical masks, that can be deployed in any setting, especially in remote areas where electricity is not readily available.”
Read More: https://doi.org/10.1016/j.ajic.2022.02.019
Authors: Kevin Vos, University of Calgary; Paul M.K. Gordon, University of Calgary; Belinda Heyne, University of Calgary
Inhalation Safety of the Protective Dye Methylene Blue used in aPDI Method
Singletto’s Lendvay, Chen, and Clark, along with Xu and Cui, noted that, despite a number of existing FDA-cleared medicinal and antimicrobial uses of MB, no studies existed that determined if MB applied to facemasks for aPDI could be inhaled by healthcare workers. They sprayed a panel of N95 respirators, medical masks, and cloth masks with five cycles of 1,000 uM MB solution and subjected coupons to three-fold airflow rates as would be expected for a healthcare worker wearing MB-treated PPE. No MB was detected for any samples above the limit of detection, demonstrating that even at 500 times the amount of MB needed to decontaminate N95 respirators and medical masks via aPDI (per the WHO Rational Use of PPE bulletin) there was no residual risk of inhalation exposure to MB following treatment. The authors concluded, “…no detectable MB was observed, thus providing safety evidence for the use of methylene blue and light exposure for mask decontamination.”
Read More: https://doi.org/10.1016/j.ajic.2022.03.003
Authors: Thomas Lendvay, University of Washington; Jinwei Xu, Stanford University; James Chen, Singletto; Tanner Clark, University of Washington; Yi Cui, Stanford University
This new body of peer-reviewed research further validates the aPDI method as a breakthrough decontamination and ongoing inactivation method. Not only can aPDI play a critical role in current pathogen protection, including the ongoing COVID-19 pandemic, but it can also be an essential tool for protection against emerging threats of global interest and for future pandemic preparedness. Singletto, under the scientific and medical leadership of Drs. Chen, Lendvay, Mores, and Clark, continues research and development of this core technology. Singletto’s aPDI technology, called Oxafence, is being developed to meet the needs of healthcare, military, industry, and consumers – providing ongoing Active Protection from pathogens where it matters most.
The Oxafence technology, and the deployment of MB in this use case, is not yet approved or currently available for use, sale or distribution in the U.S. Singletto will continue to update http://www.singletto.com with opportunities as relevant.
Singletto Contact: John Bjornson, CEO | John@Singletto.com | www.Singletto.com