Our journey began with a burning question: How do we deal with the constant disease outbreaks and the emergence of antibiotic resistant microbes? The dangerous pathogens responsible for this are everywhere, in our offices, in hospitals, in airplanes, in our food. Controlling the spread of pathogens such as Listeria on food, Acinetobacter in hospital rooms and Influenza in the air, is becoming an increasingly complex challenge. In particular, the annual toll of foodborne diseases has reached an alarming 600 million cases and 420,000 deaths worldwide. Globalization of the food supply, growth of transcontinental travel and an overloaded healthcare system has made this problem exponentially worse. Current antimicrobial application methods require washes, sprays and chemical methods which have many disadvantages, including environmental waste, toxicity and antimicrobial resistance.
Nanotechnology to the Rescue!
For the past few decades, scientists have been talking about materials in the nanoscale and their unique properties, as compared to those of “bulk” materials and nanotechnology as a transformative technology with applications in every scientific field. Now researchers and industry have the ability to engineer and characterize these nanoscale particles, and nanotechnology has become a major economic force in the 21st century. Since many of the current chemical based antimicrobial intervention approaches have serious drawbacks stated earlier, nanotechnology can provide attractive alternative solutions.
Turning water into a new “Bug killer”: Engineered Water Nanostructures (EWNS)
Imagine this: a fine mist of tiny, invisible, nanoscale engineered water nanodroplets—each 2,000 times smaller than the width of a human hair—that can be engineered from deionized water into the nanoscale, with these nanoscale droplets possessing unique physico-chemical and anti-microbial properties that can render them lethal in the battle against infectious diseases. These “Engineered Water Nanostructures” (EWNS) discovered and studied at Harvard and its Center for Nanotechnology and Nanotoxicology are currently considered a nanotechnology based, “game changing” antimicrobial platform with applications in food safety, airborne infectious disease control and wound healing. Researchers at Harvard under the leadership of Prof. Philip Demokritou embarked on projects funded by the USDA/NIFA, NIH and Industrials partners over the last few years to further develop and implement this emerging technology.
The unique nature of EWNS
The EWNS nanoparticles are synthesized using a low energy, combined electrospray and ionization process, which can transform deionized water into a nano-aerosol. EWNS nanoparticles have unique tunable physico-chemical properties: They are in the nanoscale, (approximately 25nm, about 10 times wider than a strand of human DNA), are highly mobile in air, contain reactive oxygen species (ROS) from the ionization of the water and can incorporate in their chemical structure other nature derived antimicrobials to enhance their antimicrobial efficacy. They are engineered with a negative electric charge, which was shown to increase their surface energy and tension reducing their evaporation and extending their life in the air into hours. More importantly, their charge can be used to target them on surfaces using an electric field turning them into a highly efficient nano-carrier platform to deliver Active Ingredients (A.I.) with antimicrobial properties. Such highly mobile EWNS aerosol could act as Nanobombs, delivering their ROS and other AI payload to pathogens, rupturing their cell membranes and destroying them.
EWNS as an antimicrobial technology for food safety, quality and beyond
With funding from USDA/NIFA, the EWNS technology was tested against common foodborne pathogens, such as E. coli and Listeria moncytogenes. Here, we incorporated in the EWNS chemical structure, various ‘Nature-inspired’ antimicrobials, as Active Ingredients (‘A.I.’) such as citric acid, lysozyme, H2O2, etc. to produce EWNS based nano-sanitizers. The application of these EWNS based nano-sanitizers to inactivate food pathogens proved highly efficient. EWNS carrier platform delivers in a “dry” aerosol form active ingredients in just nano-pico gram level, resulting in food disinfection with treatment times in the order of a few minutes. This inactivation was achieved with no chemical byproducts and miniscule chemical residues on food surfaces and no sensory effects! Furthermore, the impressive antimicrobial efficacy of the EWNS technology prompted us to look beyond food safety, with application to air disinfection and wound healing.
Looking back and moving forward:
The EWNS technology and its emerging applications related to foodborne and airborne disease control proves that nanotechnology has a major role to play in the field of public health engineering. Our journey into understanding the unique nanoscale phenomena and properties of materials in the nanoscale resulted to the development of a potentially game changing technology that can be a useful tool to address one of the grand societal challenges facing agricultural and food systems: the prevention of foodborne diseases. We hope that this journey inspires researchers in nano-science to think outside of the disciplinary box and dive into the vast ocean of opportunities that interdisciplinary nanoscience research has to offer.
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