Calcination Temperatures, Compositions and Antimicrobial Properties of Heterostructural ZnO–CuO Nanocomposites from Calotropis Gigantea Targeted for Skin Ulcer Pathogens

Abstract

<jats:title>Abstract</jats:title> <jats:p>An eco-friendly green route is employed for the successful synthesis of heterostructured ZnO-CuO nanocomposites using Calotropis gigantea plant and the investigation of their antimicrobial properties against skin ulcer pathogens. Binary ZnO-CuO nanocomposites prepared at calcination temperature of 300 °C exhibited superior antimicrobial effect on S. aureus, whereas the negative control sample did not show any antibacterial activities. High ZnO nanoparticles of 75 wt.% ZnO-CuO nanocomposites showed zero count of Staphylococcus aureus at a minimum inhibitory concentration of 0.625 mg/mL and minimum bactericidal concentration (MBC) of 2.5 mg/mL. Interestingly, the 75 wt.% ZnO-CuO nanocomposites exhibited strong antimicrobial activity against multi-drug resistant pathogens, with MBC ranging from 0.3125 mg/mL to 1.25 mg/mL. A time-kill assay captured a reduction in viable count from 4.3 log 10 to 1.3 log 10 after 12 h of incubation for S. aureus . Elucidating the antimicrobial activities could be useful for identifying novel ways to incorporate ZnO-CuO nanocomposites in polymers for applications in biocide materials, such as for wound dressing. Further, molecular studies are needed to explain the underlying biocidal mechanism of ZnO-CuO nanocomposites especially in the presence of Cu 2+ and Zn 2+.</jats:p>