Synthesis, Characterization, and Antibacterial Properties of Silver, Copper, and Ag/Cu Bimetallic Nanoparticles Supported on Organically Modified Bentonite

Abstract

This study reports the synthesis of antibacterial nanocomposites composed of silver, copper, and bimetallic Ag–Cu nanoparticles immobilized on organically modified bentonite (B-CTA) using a simple and efficient chemical reduction approach. Raw bentonite was first homoionized with sodium chloride and subsequently modified with a cationic surfactant to obtain B-CTA. The organoclay was then exchanged with Ag⁺, Cu²⁺, or mixed metal ions and chemically reduced to generate metallic nanoparticles. The resulting nanocomposites were characterized by FTIR, XRD, XRF, SEM, and TEM, confirming the successful formation of face-centered cubic silver and/or copper nanoparticles associated with the clay structure. Antibacterial activity was evaluated against Gram-negative (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and Gram-positive (Staphylococcus aureus ATCC 25923 and S. aureus ATCC 43300) strains. All nanocomposites exhibited strong antibacterial performance, with the bimetallic Ag–Cu system showing enhanced efficacy. These findings highlight the potential of clay-based nanocomposites as effective materials for antimicrobial applications.