AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
A Novel Method for Bacteria Inactivation Using Engineered Water Nanostructures
GEORGIOS PYRGIOTAKIS, James McDevitt, Toshiyuki Yamauchi, Yosuke Mitsuyama, Philip Demokritou, Harvard University
Abstract Number: 152 Working Group: Nanoparticles and Materials Synthesis
Abstract Herein, we present a nanotechnology-based, novel method for microbial disinfection that utilizes Engineered Water Nanostructures (EWNS) synthesized via electrospraying. The atmospheric water vapor is condensed on a Peltier cooled electrode and high voltage (5 kV) is applied to spray the water. During this process ROS and RNS are generated. A a high volume (up to 15 lpm) EWNS generator was constructed which also allows to vary the particle concentration levels up to 500,000 particles per cubic centimeter.
The physicochemical properties of the EWNS such particle size distribution, surface charge and chemical species were also investigated in this study. The ability of the EWNS to inactivate bacteria on both surfaces and in the air was investigated. For the surface bacteria inactivation experiments a number of vegetative bacteria (Serratia Marcenses, Staphylococus aureus) and a spore (Bacilus Subtilis) were exposed over time to EWNS and the bacteria inactivation potential was assessed. Similarly, in a chamber experiment the ability of the EWNS to inactivate airborn serratia marcenses was examined. Serratia bacteria were aerosolized using a collison nebulizer and exposed to EWNS aerosol in an environmental chamber (1000 lt). The bacteria inactivation potential in the air was assessed under different simulated environmental conditions (steady state and decay scenarios) using a culture system approach. The bio aerosol size distribution in the chamber was measured using an Andersen bio-sampler.
Our results show that the generated EWNS have unique physico-chemical properties. Their median diameter is approximately 18 nm, and have a highly charged surface (10 electrons per particle). Their charge increases the effective surface tension lowering the evaporation rate, extending their lifetime to more than 5 minutes. The EWNS also contain in their core reactive oxygen species (ROS) such as hydroxyl radicals and superoxides. The surface bacteria inactivation experiments showed that for Serratia Marcescens and staph aureus there was more than a 2-log10 and 1-log10 reduction respectively. Similarly the air inactivation experiments showed that the EWNS aerosol can reduce the presence of bacteria by 50% and accelerate the decay of the bacteria in a room environment.