Antimicrobial Activity and Prevention of Bacterial Biofilm Formation of Silver and Zinc Oxide Nanoparticle-Containing Polyester Surfaces at Various Concentrations for Use

Abstract

Food contact surfaces are primary sources of bacterial contamination in food industry processes. With the objective of preventing bacterial adhesion and biofilm formation on surfaces, this study evaluated the antimicrobial activity of silver (Ag-NPs) and zinc oxide (ZnO-NPs) nanoparticle-containing polyester surfaces (concentration range from 400 ppm to 850 ppm) using two kinds of bacteria, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli), and the prevention of bacterial biofilm formation using the pathogen Listeria monocytogenes. The results of antimicrobial efficacy (reductions ≥ 2 log CFU/cm 2 ) showed that at a concentration of 850 ppm, ZnO-NPs were effective against only E. coli (2.07 log CFU/cm 2 ). However, a concentration of 400 ppm of Ag-NPs was effective against E. coli (4.90 log CFU/cm 2 ) and S. aureus (3.84 log CFU/cm 2 ). Furthermore, a combined concentration of 850 ppm Ag-NPs and 400 ppm ZnO-NPs showed high antimicrobial efficacy against E. coli (5.80 log CFU/cm 2 ) and S. aureus (4.11 log CFU/cm 2 ). The results also showed a high correlation between concentration levels and the bacterial activity of Ag-ZnO-NPs (R 2 = 0.97 for S. aureus, and R 2 = 0.99 for E. coli). They also showed that unlike individual action, the joint action of Ag-NPs and ZnO-NPs has high antimicrobial efficacy for both types of microorganisms. Moreover, Ag-NPs prevent the biofilm formation of L. monocytogenes in humid conditions of growth at concentrations of 500 ppm. Additional studies under different conditions are needed to test the durability of nanoparticle containing polyester surfaces with antimicrobial properties to optimize their use.Foods 2020, 9, 442 2 of 15 studies include the development of antimicrobial surfaces capable of preventing and/or inhibiting bacterial adhesion [8][9][10][11].Metal agents such as silver, copper, zinc, titanium, and cobalt have antimicrobial properties. When these agents remain on surfaces, their biocidal properties are gradually released onto the surface through a process of ion exchange, providing continuous, lasting antimicrobial activity [12][13][14]. The biocidal properties of metal agents depend on the characteristics of their nanoparticles, such as size, distribution, morphology, and the release of very small quantities of their cations on the substrates on which they are acting [15,16]. The antimicrobial activity of these agents is also affected by extrinsic factors, such as the pH of the medium, time of exposure, concentration, UV radiation, and the presence of other substances or microorganisms [17][18][19].Two of the most extended nanocomposites for antibacterial purposes are silver and zinc oxides embedded in polymeric matrices [20][21][22]. The antimicrobial activity of silver (Ag) and zinc (Zn) repels or inhibits the initial attachment of bacteria by either exhibiting an anti-biofouling effect or by inactivating cells in contact with surfaces, causing their death [23,24]. Additionally, the antibacterial properties of these agents reduce the risk o...

Bio-inspired facile fabrication of silver nanoparticles from in vitro grown shoots of Tamarix nilotica: explication of its potential in impeding growth and biofilms of Listeria monocytogenes and assessment of wound healing ability

“…In a recent report, AgNPs containing polyester surface exhibited effective inhibition of biolm formed by L. monocytogenes at concentration of 500 ppm. 41 The AgNPs have been wide reported for antibiolm activity in literature. For instance, AgNPs synthesized using aqueous extract of Withania somnifera reduced the biolms development of S. aureus, S. mutans, P. aeruginosa, and S. typhimurium by 40, 54, 48, and 50.72, respectively, compared their respective untreated controls.…”

Antimicrobial Effect of Chitosan Films on Food Spoilage Bacteria

“…Moreover, these nanoparticles may reduce the attachment of microbes to different surfaces [ 38 , 39 ]. Zinc oxide nanoparticles containing polyester surfaces showed high antibacterial activity against S. aureus and E. coli [ 40 ]. This action of zinc oxide repels or inhibits the initial step of bacterial adhesion [ 41 , 42 ].…”

Hollow mesoporous silica capsules loaded with copper, silver, and zinc oxide nanoclusters for sustained antibacterial efficacy

“…While Ag nanoparticles have been shown to accumulate on the surface of the bacterial membrane followed by the penetration into the cell leading to an increase in permeability and thus resulting in bacterial death, the antimicrobial activity of ZnO nanoparticles is thought to be mainly induced by oxidative stress. 60 In this context, binding of Zn + ions to the thiol groups of the respiratory enzymes has been shown to lead to the production of reactive oxygen species (ROS), which can cause damage of the bacterial membrane, DNA and mitochondria. 60 Nevertheless, further studies are required to analyze the different mechanisms of nanoparticles and released ions against Gram-positive and Gram-negative bacteria.…”