Evaluation of a Silver Nanoparticle Generator Using a Small Ceramic Heater for Inactivation ofS. epidermidisBioaerosols

Abstract

Silver has been known to show antibacterial activity. Recently, silver nanoparticles have been become widely used in diverse applications. In a previous work by the authors, a small nanoparticle generator that uses a ceramic heater with a local heating area was developed. The performance of the device was evaluated in terms of the silver nanoparticles it generated. In the present article, a feasibility study regarding the inactivation of bacteria bioaerosols by the developed small silver nanoparticle generator is conducted to assess its possible use for the active control of indoor bioaerosols. To simulate the inactivation of bacteria on a surface exposed to air, an antibacterial test system consisting of an airborne silver nanoparticle generator, a bacteria bioaerosol generator, and two airborne bacteria samplers with membrane filters was utilized. Spherical polydisperse silver nanoparticles with mode diameters in the range of 10 ∼ 27 nm were generated. Their size distribution was changed according the applied voltage and the airflow rate. S. epidermidis gram-positive bacteria having mode diameter of approximately 800 nm were aerosolized using a single-jet Collison nebulizer in an effort to verify the antibacterial activity of the silver nanoparticles in an air environment. With variables of 100 V and 6 L/min, the viability of S. epidermidis bacteria exposed to silver nanoparticles was lower than 5% for an exposure time ranging from 1 ∼ 9 min. The viability curve was well represented in terms of the total surface area of the exposed silver nanoparticles. From the results, it was concluded that the developed small airborne silver nanoparticle generator has considerable potential as an active antimicrobial device for use in indoor air applications.