An integrated electrolysis – electrospray – ionization antimicrobial platform using Engineered Water Nanostructures (EWNS) for food safety applications

Abstract

Engineered water nanostructures (EWNS) synthesized utilizing electrospray and ionization of water, have been, recently, shown to be an effective, green, antimicrobial platform for surface and air disinfection, where reactive oxygen species (ROS), generated and encapsulated within the particles during synthesis, were found to be the main inactivation mechanism. Herein, the antimicrobial potency of the EWNS was further enhanced by integrating electrolysis, electrospray and ionization of de-ionized water in the EWNS synthesis process. Detailed physicochemical characterization of these enhanced EWNS (eEWNS) was performed using state-of-the-art analytical methods and has shown that, while both size and charge remain similar to the EWNS (mean diameter of 13 nm and charge of 13 electrons), they possess a three times higher ROS content. The increase of the ROS content as a result of the addition of the electrolysis step before electrospray and ionization led to an increased antimicrobial ability as verified by E. coli inactivation studies using stainless steel coupons. It was shown that a 45-minute exposure to eEWNS resulted in a 4-log reduction as opposed to a 1.9-log reduction when exposed to EWNS. In addition, the eEWNS were assessed for their potency to inactivate natural microbiota (total viable and yeast and mold counts), as well as, inoculated E.coli on the surface of fresh organic blackberries. The results showed a 97% (1.5-log) inactivation of the total viable count, a 99% (2-log) reduction in the yeast and mold count and a 2.5-log reduction of the inoculated E.coli after 45 minutes of exposure, without any visual changes to the fruit. This enhanced antimicrobial activity further underpins the EWNS platform as an effective, dry and chemical free approach suitable for a variety of food safety applications and could be ideal for delicate fresh produce that cannot withstand the classical, wet disinfection treatments.

A nano-carrier platform for the targeted delivery of nature-inspired antimicrobials using Engineered Water Nanostructures for food safety applications

“…The details of the measurement have been described elsewhere (Pyrgiotakis et al, 2016;Vaze et al, 2018). A Faraday aerosol electrometer (Model 3068B, TSI, Shoreview, MN) was used to measure the aerosol current concurrently with the SMPS during particle concentration measurement.…”

“…The ROS content of each of the iEWNS nano-sanitizers was measured using the Trolox method as described by the authors in detail in a previous publication (Vaze et al, 2018). In summary, 5 mL of solution of Trolox (0.1 mM, in 0.05 M pH 7 phosphate buffer) was placed in an impinger (SKC Inc., Eighty Four, PA) and connected to the output of the iEWNS generation system.…”

Pre-treatment Technologies to Enhance Anaerobic Digestion

“…However, some reports suggest hydrophobic attraction between negatively charged surfaces of nanobubbles and these contradictory reports could be attributed to the differences in nanobubble generation techniques, surface tension, or varying molecular arrangement at the gas-liquid interface [19]. Nanobubbles with diameters of approximately 13 nm have been well-engineered as spherical water packages with gas for food safety applications whose efficiency is well established based on bubble surface stability and the electrostatic charges present on the bubble surface [20]. Besides possessing high stability, nanobubbles in liquid systems also show a high mass transfer rate and enhanced solubility in gas [21].…”

A novel method for textile odor removal using engineered water nanostructures

“…This is consistent with the previous research. 31 The ROS were mainly generated due to the corona discharge. 67-70 A stable corona discharge was observed at the tip of Taylor cone, which is similar to the research by Seto et al 50 The high voltage in the corona discharge can induce a chain reaction of high-velocity particle collisions, resulting in the generation of more ions.…”

“…The EWNS technology was rstly reported by the Panasonic Group and the Harvard University in 2012. In their previous studies, EWNS was primarily used to inactivate pathogens (different types of bacteria) [27][28][29][30] and food safety controls [31][32][33] and has been successfully applied in commerce. Later, some Chinese scholars from Tongji University developed a water ion device which is similar to the EWNS technology and applied it in the air purication area.…”