Morphological and chemical changes of aerosolized E. coli treated with a dielectric barrier discharge.

Jaione Romero-Mangado,David Loftus,Dennis Nordlund,Felipe Soberon,Ram P Gandhiraman,Stephen Daniels,Sami Sainio,Jessica Koehne,M Meyyappan,Kevin Maughan,Ian T Saunders,Gurusharan Singh,Graham Deane

doi:10.1116/1.4941367

Abstract

This study presents the morphological and chemical modification of the cell structure of aerosolized Escherichia coli treated with a dielectric barrier discharge (DBD). Exposure to DBD results in severe oxidation of the bacteria, leading to the formation of hydroxyl groups and carbonyl groups and a significant reduction in amine functionalities and phosphate groups. Near edge x-ray absorption fine structure (NEXAFS) measurements confirm the presence of additional oxide bonds upon DBD treatment, suggesting oxidation of the outer layer of the cell wall. Electron microscopy images show that the bacteria undergo physical distortion to varying degrees, resulting in deformation of the bacterial structure. The electromagnetic field around the DBD coil causes severe damage to the cell structure, possibly resulting in leakage of vital cellular materials. The oxidation and chemical modification of the bacterial components are evident from the Fourier transform infrared spectroscopy and NEXAFS results. The bacterial reculture experiments confirm inactivation of airborne E. coli upon treating with DBD.

Highlights

Cold atmospheric pressure plasmas have gained significant recognition in recent years in the field of healthcare, for example, in the treatment of living cells, sterilization of medical devices, wound healing, and blood coagulation.1–3 The plasmas are nontoxic, provide rapid and continuous antibacterial treatment, leave no residues to clean up, and are easy to scale up, compared to other approaches
This study presents the morphological and chemical modification of the cell structure of aerosolized Escherichia coli treated with a dielectric barrier discharge (DBD)
The bioaerosol containing the nebulized E. coli was directed at the top of the DBD tool, which has an internal fan that pulls the contaminated air toward the DBD

Summary

Introduction

Cold atmospheric pressure plasmas have gained significant recognition in recent years in the field of healthcare, for example, in the treatment of living cells, sterilization of medical devices, wound healing, and blood coagulation. The plasmas are nontoxic, provide rapid and continuous antibacterial treatment, leave no residues to clean up, and are easy to scale up, compared to other approaches. The plasmas are nontoxic, provide rapid and continuous antibacterial treatment, leave no residues to clean up, and are easy to scale up, compared to other approaches. The most commonly used technologies for air cleaning include high efficiency particulate air filters, UV irradiation, chemicals (spray, gel), and gas spray (ozone, hydrogen peroxide).. The most commonly used technologies for air cleaning include high efficiency particulate air filters, UV irradiation, chemicals (spray, gel), and gas spray (ozone, hydrogen peroxide).8–13 These methods, while popular, often provide suboptimal outcomes such as creating bacterial resistance, developing mutagenic outcomes if bacteria are underexposed, and are responsible for numerous health hazards when operated incorrectly (for example, radiation exposure in the case of UV). Prolonged exposure to radiation could cause skin irritation. UV irradiation for air disinfection comes in several forms, including full intensity irradiation of a room with no occupants and shielded UV irradiation done with no restrictions on human occupation. One of the biggest drawbacks of UV irradiation is that it requires direct “line of sight” exposure to be effective; “shadowing” may occur when used to treat airborne bacteria, a process whereby the exposed upper layers of a bacterial cluster are deactivated while providing a protective shield for the

Results

Discussion

Conclusion