RSM-Optimized Green Synthesis of Ag/AgCl–Cu–MgO Nanocomposites to Enhance Their Antimicrobial Activity against methicillin-resistant Staphylococcus aureus (MRSA)

Introduction:

Bio-fabrication of multifunctional nanocomposites (NCs) has attracted attentions in bio-organic and medicinal chemistry. In this study, an aqueous extract of Desmodesmus sp. was prepared to greenly synthesized Ag/AgCl–Cu–MgO NC. Also, Response Surface Methodology (RSM) was applied to maximize antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA).

Methods:

An experimental design (24 runs) was developed, which included precursor salts concentration (Mg, 0.5, 1.25, and 2 Mm, Cu and Ag, 1, 3, and 5 mM) and Desmodesmus sp. extract concentration (10, 17.5, and 25%). The mixtures were stirred for 3 hours at 50°C under alkaline conditions, and they were centrifuged after overnight aging, and calcinated at 60°C. Antibacterial activity, assessed by agar well diffusion assay. RSM predicted the optimum formulation, then experimentally validated. The optimized NC was characterized by FESEM, EDX mapping, and FTIR analysis.

Results:

Predicted inhibition zone was [19.45] mm with optimal condition (Ag 5 Mm, Cu 5 Mm, Mg 1.24 Mm, Extract 10% v/v), while the experimentally validated value was [18 ± 1.44] mm, indicating good agreement between model and experiment. The model showed satisfactory fit with R² = [0.79]. FESEM showed average size of 90.77 nm and EDX mapping confirmed the composite distribution of Ag, Cl, Cu, Mg on bioorganic matrix, while FTIR demonstrated algal biomolecules as capping and stabilizer.

Conclusion:

This statistically optimized, microalgal-mediated strategy provides an environmentally friendly way for preparing Ag/AgCl–Cu–MgO NC with promising antibacterial activity against MRSA compared to previous studies.