Antimicrobial effect of Ag-Cu nanocomposites produced via extrusion method on Escherichia coli and Staphylococcus aureus

The most important application of nanotechnology in the food industry is the production of active packaging with antimicrobial properties, packaging with special mechanical properties in terms of gas and heat exchange and nanosensors in intelligent packaging. The aim of this study was to investigate the antimicrobial effect of silver and copper nanocomposites on Escherichia coli and Staphylococcus aureus. Nanocomposites containing silver and copper nanoparticles in 1, 3, 5 and 7% percentages were produced by extrusion method and were subjected to nanometric analysis. Then, the antimicrobial test of nanocomposites was performed on commercial strains of Staphylococcus aureus and Escherichia coli by measuring the inhibition of growth in the culture medium.  The data showed that the size of copper and silver nanoparticles was in the range of 20 to 50 nm and the dispersion of nanoparticles on the surface of nanocomposites was uniform with high purity. Antimicrobial test of nanocomposites showed that with increasing the percentage of nanoparticles, the diameter of the growth inhibition of nanocomposites increased significantly and the rate of inhibition of growth of silver nanoparticles was higher than copper (p≤0.05).  Staphylococcus aureus was more sensitive to copper and silver nanoparticles than Escherichia coli (p≤0.05). The results of the present study showed that silver and copper nanocomposites with high antimicrobial properties can be used for food packaging.