Inhibition of various gram-positive and gram-negative bacteria growth on selenium nanoparticle coated paper towels

Abstract

There are wide spread bacterial contamination issues on various paper products, such as paper towels hanging in sink splash zones or those used to clean surfaces, filter papers used in water and air purifying systems, and wrappings used in the food industry; such contamination may lead to the potential spread of bacteria and consequent severe health concerns. In this study, selenium nanoparticles were coated on normal paper towel surfaces through a quick precipitation method, introducing antibacterial properties to the paper towels in a healthy way. Their effectiveness at preventing biofilm formation was tested in bacterial assays involving Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis. The results showed significant and continuous bacteria inhibition with about a 90% reduction from 24 to 72 hours for gram-positive bacteria including S. aureus and S. epidermidis. The selenium coated paper towels also showed significant inhibition of gram-negative bacteria like P. aeruginosa and E. coli growth at about 57% and 84%, respectively, after 72 hours of treatment. Therefore, this study established a promising selenium-based antibacterial strategy to prevent bacterial growth on paper products, which may lead to the avoidance of bacteria spreading and consequent severe health concerns.

Keywords: antibacterial; paper towels; selenium nanoparticles.

Figure 1

Light image of selenium coated and uncoated paper towels. Notes: The three pieces on the top are paper towels without selenium coating. The three on the bottom are paper towels coated with selenium nanoparticles. The diameter of each sample equals to 7 mm.

Figure 2

Scanning electron microscopy images. Notes: Scanning electron microscopy images of (A) a paper towel with a selenium coating at a 3.5 k magnification, (B) a paper towel without a selenium coating at a 3.5 k magnification, and (C) the paper towel in image (A) at a 10.0 k magnification.

Figure 3

Tension tests for paper towels in various conditions. Notes: Tension tests for paper towels in various conditions (A) dry and uncoated; (B) dry and selenium nanoparticle coated; (C) wet and uncoated; and (D) wet and selenium nanoparticle coated.

Figure 4

The growth of Staphylococcus epidermidis on the surface of paper towels. Notes: There was more than a 90% inhibition of bacteria growth compared with control groups. Data are mean ± standard deviation, n=3; *^, **^, ***P<0.05 compared with the control group (uncoated paper) after either 24, 48, or 72 hours.

Figure 5

The growth of Pseudomonas aeruginosa on the surface of paper towels. Notes: Data are mean ± standard deviation, n=3; *^, **P<0.05 compared with the control group (uncoated paper) after either 48 or 72 hours.

Figure 6

The growth of Escherichia coli on the surface of paper towels. Notes: Data are mean ± standard deviation, n=3; *^, **^, ***P<0.05 compared with the control group (uncoated paper) after either 24, 48, or 72 hours.

Figure 7

The amount of adsorbed total proteins on selenium coated and uncoated paper towels. Notes: Data are mean ± standard deviation, n=3; *^, **^, ***P<0.05 compared with the paper towels without (w/o) coating for a treatment after either 24, 48, or 72 hours (hrs).