Bimetallic Pd/CuO nanoparticles obtained by laser re-irradiation in liquids for antibacterial applications

Abstract

Antimicrobial resistance (AMR) is considered a major global health problem of the 21st century. Noble metal nanoparticles (NPs) have attracted increasing attention as a promising tool to fight against resistant infections. In this research, we explore bimetallic NPs, as they can give rise to further and improved physicochemical and biological properties. In this work, monometallic Cu/CuO and Pd NPs were synthesized by laser ablation. Afterwards, these NPs were mixed and the resulting colloidal solution was multiply re-irradiated with the aim of producing Pd/CuO bimetallic NPs. All the NPs presented rounded shape and crystalline microstructure. Although the re-irradiated NPs contained both precursor materials, all characterization techniques agreed on the occurrence of an intermetallic alloy of both materials, Cu₃Pd, that is concluded to be formed as a consequence of the interaction between the laser beam and the mixture of monometallic NPs. With the objective of studying antimicrobial activity against Staphylococcus aureus, the CuO NPs, Pd NPs and Pd/CuO NPs were immobilized on the surface of titanium discs. Ion release was tracked during the first 24 h and cytotoxicity of the immobilized NPs was as well tested with HFF-1 human fibroblast cell line. Bimetallic Pd/CuO NPs showed a significant inhibitory effect on S. aureus and no toxic impact on fibroblasts.