The emergence of infectious diseases due to both gram positive and gram negative bacterial strains poses a serious threat to public health. Over the years, antibiotics have been used to control infections resulting from both community and hospital environments. However, with the emergence of antibiotic-resistant bacterial strains, resulting from misuse and outright abuse of antibiotics, it has become a major global health problem.¹ Therefore, it is important to find new classes of entities with broad spectrum activity and different modes of action to combat drug resistant pathogens.

Metallic nanoparticles have received great attention in many applications including catalysis, electronics, photonics and also in medicines due to its special and unique properties which differ from the bulk materials and could be attributed to its small size and large specific surface area.² Nanostructured organic and inorganic particles such as metal oxides of zinc³, copper⁴, and iron⁵ find their application in food preservation, medical practices and in biomedical research. Since nanoparticles can be smaller in size than bacterial pores, they will have a unique ability of crossing the cell membrane. As limited information is available on the antimicrobial properties of metallic nanoparticles, in this work we have synthesized NiO, CuO, ZnO and WO₃ metallic nanoparticles by hydrothermal method and studied their antimicrobial activities against four gram negative pathogenic strains Escherichia Coli, Klebsiella pneumoniae, Serratia marcescens (Fig. 1a), Pseudomonas aeruginosa; and three Gram positive pathogenic strains Staphylococcus aureus, Listeria monocytogenes (Fig. 1b), Bacillus cereus and two fungal strains, Aspergillus niger and Trichoderma harzianum. Our investigated metallic nanoparticles showed strong inhibitory activity against gram negative strains than gram positive strains and potential activity against both fungal strains. In this work, we shall further investigate a detail comparative study on antimicrobial activities of tested metallic nanoparticles.

Acknowledgment

Authors acknowledge financial supports from the Ministry of Science & Technology, Bangladesh funded project “FACSens” under the special allocation to science & technology activity programme; and Science Foundation Ireland funded project “SweatSens” under the grant agreement No. 14/TIDA/2455.

Corresponding authors email addresses: kafil.mahmood@tyndall.ie and mamun.jamal@chem.kuet.ac.bd

Reference

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Figure 1. (a) Zone of inhibition against S. marcescens; (b) Zone of Inhibition against L. monocytogenes.