Antibacterial activity of Co, Ni, and Pd-infused CaO 0.85 ZrO 0.15 : a novel nanocomposite with broad-spectrum

Abstract In the present study, a Co–Ni–Pd/CaO 0.85 ZrO 0.15 trimetallic nanocomposite was synthesized and characterized using Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and transmission electron microscopy (TEM) to characterize its structural and morphological properties. The antibacterial activity of the synthesized nanocomposite was also evaluated against selected gram- positive and gram-negative bacterial strains. The results of FTIR confirmed the formation of acetylacetonate ligands and metal–oxygen bonds in the nanocomposite. XRD patterns confirmed the crystalline structure with identified diffraction peaks of cubic CaO and ZrO 2 phases. TEM images showed agglomerated nanoparticles with sizes ranging from 45 to 85 nm. The novelty of this study focuses on the incorporation of Co, Ni, and Pd into the CaO–ZrO 2 matrix, which leads to the generation of multiple active surface sites and enhances synergistic interactions, thereby improving the antibacterial performance. The antibacterial activity of the prepared nanocomposite was assessed against gram-positive and gram-negative bacteria. Increased inhibition zones were noted at higher concentrations, recorded 9.80 mm for Staphylococcus lentus , 9.73 mm for Bacillus subtilis , 11.33 mm for Pseudomonas aeruginosa , and 11.65 mm for Escherichia coli at 10 000 ppm. The nanocomposite showed higher antibacterial activity against gram-negative bacteria ( P. aeruginosa and E. coli ) than the gram-positive one ( Staphylococcus lentus and Bacillus subtilis ). These results provide a preliminary indication of the antibacterial potential of the nanocomposite, particularly against gram-negative bacteria. Nevertheless, further biological studies are necessary to comprehensively evaluate and confirm its antibacterial efficiency.