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

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.