Background: The emergence of drug resistant pathogens is a major concern to the scientific
community. Novel approaches such as the use of functionalized nanomaterials with antimicrobial
activity is required to treat infectious diseases.
Objective: In the present study, the metallic nanoparticles (iron, gold, zinc oxide and copper oxide)
were evaluated for the antimicrobial, biofilm inhibitory and anti-infective activity against human
pathogens methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa PA01.
Methods: The efficacy of nanoparticles on the planktonic growth of clinically relevant pathogens was
determined by MIC. Further, the effect of nanoparticles was studied on their biofilms using crystal
violet microtiter plate assay and fluorescent microscopy. The cytotoxicity of nanoparticles was studied
in HT29 cell line.
Results: The nanoparticles of copper and zinc oxide (size < 50 nm) were more effective against Grampositive
and Gram-negative pathogens in comparison to gold and iron nanoparticles. The ZnO
nanoparticles had an MIC in the range of 3.125 μg/ ml and 6.25 μg/ ml against the tested pathogens.
The nanoparticles at the tested concentration reduced biofilm burden by > 75% in the pathogens. The
nanoparticles showed cytotoxicity in HT 29 at 20 μg/ ml.
Conclusion: The results of the study showed that of all the tested nanoparticles, ZnO nanoparticles
had significant antimicrobial activity against the drug resistant pathogens and could be used at concentrations
less toxic to mammalian cells. Hence, ZnO nanoparticles have the potential for the design of
novel antibacterial agents and therapeutics.