Antibacterial, Anti-Biofouling, and Antioxidant Prospects of Metal-Based Nanomaterials

Three metallic nanomaterials, i.e., iron, copper, and bimetallic iron-copper were easily synthesized using a wet-chemical method and were properly characterized. The materials were tested against two bacterial strains, Staphylococcus aureus and Escherichia coli in order to evaluate their antibacterial activity, as well as their biofilm formation inhibition properties. The total inhibition of bacterial growth, at low mg/mL concentrations, implies the satisfactory antibacterial activity of the nanomaterials against bacteria. Between the two bacterial strains used, E. coli is more susceptible to the effect of the nanomaterials than S. aureus. However, the results for the respective biofilms are significantly different since S. aureus biofilm formation is more easily inhibited. There are differences in the way of action against the two different bacteria and diverse mechanisms of action are proposed to justify them. Furthermore, positive 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical tests demonstrated that the nanomaterials are free-radical scavengers while TBARS (thiobarbituric acid reactive substances) tests evidenced their lipid oxidation inhibition properties, although at high concentration levels. Copper nanoparticles proved to be the most effective of the three materials tested, against DPPH radicals and lipid peroxidation followed by the Fe-Cu and lastly by the Fe nanoparticles. The intrinsic magnetic properties of iron-based materials can provide long-term benefits for antibacterial or anti-biofouling treatment in water purification systems as well as for antioxidant activity purposes.