Synthesis and Antimicrobial Activity of Silver/Copper Oxide/Clay Hybrid Nanocomposites Against Gram-Positive and Gram-Negative Bacteria.

Abstract

Background: The rapid surge in bacterial resistance to classical antibiotics and antimicrobial agents has driven researchers to identify new classes of antimicrobial agents. At the nanoscale, nanotechnological progress has strongly underscored the application of silver and copper since they present high antimicrobial activities toward gram-positive and gram-negative bacteria. Nanostructures containing these two elements-all the more so for hybrid nanocomposites-have been scantily the subject of investigated. The present work aims to develop and study a silver/copper oxide/clay hybrid nanocomposite.

Methods: Nanocomposites of silver, copper oxide, and their hybrid with clay were synthesized via chemical precipitation under controlled pH (9-11) and temperature (60-90°C) conditions. The antibacterial activity was assessed using standard 0.5 McFarland-adjusted bacterial inocula. Characterization was performed using FTIR, XRD, FESEM, and TEM techniques. MIC and MBC were determined through serial dilution, and data were analyzed using one-way ANOVA and Tukey's test (SPSS v26).

Results: The results indicated that the fabricated nanocomposite was impure, with nanosilver particles measuring 30-40 nm and copper oxide particles measuring 200-250 nm. The morphological properties of synthesized Ag/Cu2O/clay nanocomposites were evaluated using X-ray diffractometer analysis. The minimum inhibitory concentration (MIC) of the hybrid nanocomposite against Staphylococcus aureus and Bacillus subtilis was 1024 μg/ml, and for Escherichia coli and Pseudomonas aeruginosa 2048 μg/ml. The minimum bactericidal concentration (MBC) against Staphylococcus aureus and Bacillus subtilis was 4096 μg/ml, and for Escherichia coli 4096 μg/ml, and Pseudomonas aeruginosa 8192 μg/ml.

Conclusion: These results showed that the antimicrobial property of silver/copper/clay hybrid nanocomposite was better than copper/silver and clay nanocomposite against gram-positive bacteria, while showing a similar effect against gram-negative bacteria.