Antimicrobial Properties of Copper-Doped ZnO Coatings under Darkness and White Light Illumination.

Iman A Hassan,Sean P Nair,Claire J Carmalt,Sanjayan Sathasivam

doi:10.1021/acsomega.7b00759

Abstract

We report the first antimicrobial study of transparent and robust Cu-doped ZnO coatings that displayed potent antimicrobial activity that resulted in bacterial (Escherichia coli) reduction below detection limits within 6 h of illumination via a white light source that is found in hospital environments. The same bacterial reduction rate was observed even under darkness for 4.0 atom % Cu-doped ZnO films thus providing an efficient 24 h disinfection. All films were produced via a novel, inexpensive, and easily scalable route and were also thoroughly analyzed for their material properties.

Highlights

Nosocomial infections are a major concern for hospitals and healthcare institutions globally.[1−3] Many of these infections are caused by multidrug-resistant strains of bacteria
In hospital environments, which are the epicenter of a majority of these antimicrobial drug-resistant infections, 80% of infections are due to contaminated touch surfaces.[6−8] Disinfection of such surfaces is key to the fight against spread of antimicrobial bacteria
In this article, we show the novel use of aerosol-assisted chemical vapor deposition (AACVD) for the synthesis of the Cu-doped films

Summary

Introduction

Nosocomial infections are a major concern for hospitals and healthcare institutions globally.[1−3] Many of these infections are caused by multidrug-resistant strains of bacteria. Zinc oxide is an inexpensive semiconducting material extensively used in the optoelectronic industry due to its wide band gap (3.3 eV at room temperature) and high electrical conductivity. It has found use as an antimicrobial agent and has seen application in the lining of food packaging to reduce spoilage.[12] The mechanism for the activity is complex and not fully understood, but it is thought to be through various paths, including the uptake of Zn2+ ions (released into the surrounding environment from the metal oxide surface) into cells. Upon irradiation by UV light with energy above 3.3 eV (sunlight and fluorescent light sources commonly found indoors emit light ca. 4% in the UV wavelengths, and some of this UV light will have energy above 3.3 eV), ZnO oxidizes and reduces water and oxygen (respectively) to produce reactive oxygen species (ROS).[12,17] These species can cause damage to an organism’s cell membrane, DNA, and protein through Fenton type reactions, which result in cell death.[18−23] Some believe this oxidative stress to be the primary mode of antibacterial activity of most bactericidal metal oxides.[24−27]

Methods

Results

Conclusion