Press Release, Boston MA, 11/12/2019

The transmission of infectious diseases is a critical public health issue facing the world. In 2017, there were estimated 6.3 million incidences of diarrheal diseases and 17.5 million incidences of respiratory infections globally. These infectious diseases remain one of the biggest causes of mortality around the world. The pathogens responsible for these diseases, such as E. coli O157:H7, human norovirus and adenovirus, can be easily transmitted through hand contact. Thus, hand hygiene is an important factor in curtailing the spread of these pathogens. To this effect, current hand hygiene practices involve the use of hand rubs with antiseptics and washes. However, there are various drawbacks and limitations to these methods. Frequent hand washing can cause irritant contact dermatitis, using hot air hand dryers after washing can disperse microorganisms into the air and exacerbate disease transmission. The antiseptic chemicals used in hand soap and hand rubs, such as triclosan and chlorhexidine, have negative effect on human health and can result in increased antimicrobial resistance. Moreover, these methods also require significant amounts of water, and with the growing global challenge of water scarcity, a more sustainable way of addressing this issue is needed.

Researchers at the Center for Nanotechnology and Nanotoxicology at the Harvard T.H. Chan School of Public Health led by Professor Philip Demokritou, have recently been working on developing antimicrobial platforms using novel nanotechnology-based approaches. These efforts have led to the development of the Engineered Water Nanostructures (EWNS). These EWNS based nano-sanitizers, produced from water-based solutions of nature-derived active and non-toxic antimicrobials such as hydrogen peroxide, citric acid, lysozyme and nisin, possess several unique properties. They have a tunable size in nanoscale, have a lifespan of hours in air, are highly mobile and can carry both nature-derived and non-toxic antimicrobial agents and reactive oxygen species (ROS), which can kill pathogens in air and on surfaces. This highly versatile antimicrobial platform has been applied with great success to address major public health challenges such as food safety and air disinfection.

In the latest study from the group, the researchers utilized the EWNS platform to tackle the major public health challenge of enhancing hand hygiene. A cocktail of various “nature-inspired” antimicrobials, such as citric acid, hydrogen peroxide, and antimicrobial peptides, as well as bacteriocins (lysozyme and nisin) were delivered to contaminated surfaces using the EWNS platform. Compared to traditional hand rub and washing “wet” approaches, the EWNS approach can achieve similar or higher levels of pathogen inactivation in just 30 seconds with orders of magnitude lower amounts of antimicrobial agents delivered to the hands (picograms to nanograms). More importantly, there is no forced air flow and hands will remain “dry” as only microliters of water is used. It should also be noted that since a cocktail of “nature-inspired” antimicrobial agents is used, the EWNS approach has a broader antimicrobial spectrum and can potentially slow the development of antimicrobial resistance associated with using chemical hand disinfectants.

Runze Huang, a post-doctoral fellow and the lead author on the study remarked, “This EWNS based approach has shown the ability to kill hand hygiene-related microorganisms. Moreover, only nanogram levels of “nature-inspired” active ingredients are utilized, and no toxic chemical by-products are left behind making this “dry” and “airless” approach a highly efficient one.”

“The EWNS technology represents a novel solution to the not yet sufficiently addressed problem of hand hygiene-related transmission of diseases. With the highly effective targeted delivery of nanogram quantities of antimicrobials to hands, the hands remain dry. Thus, making this technology the next step in terms of sustainability,”added Nachiket Vaze, a research associate and member of the EWNS team.

The study is the latest in a series of many published on the EWNS technology performed at the Center for Nanotechnology and Nanotoxicology. The center director Dr. Philip Demokritou concluded, “The chapter of infectious diseases is still open unfortunately, to the contrary of what was believed decades ago with the invention of antibiotics. New innovative approaches are needed in our continuous battle with infectious diseases and that’s where nanotechnology comes in play. The EWNS platform has the potential to be a disruptive technology which can be used to kill infectious microorganisms on surfaces and in the air in a sustainable manner”.

The ACS Sustainable Chemistry and Engineering publication can be accessed here (https://pubs.acs.org/doi/abs/10.1021/acssuschemeng.9b05057). For more information on this and other nano-related research at the Harvard T.H. Chan School of Public Health, please visit our website at www.hsph.harvard.edu/nano

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