Diverse approach for the evaluation of antibacterial, antioxidant, and cytotoxicity properties: Plant-mediated synthesis of AgO, ZnO and AgO-ZnO bimetallic nanoparticles using Theobroma cacao leaf extract

Plant-mediated synthesis of nanoparticles offers numerous potential applications in both environmental and biomedical fields. This study describes the biosynthesis, characterization, and potential uses of monometallic nanoparticles (MNPs) like silver oxide (AgO), zinc oxide (ZnO), and silver oxide-zinc oxide (AgO-ZnO) bimetallic nanoparticles (BNPs) using Theobroma cacao leaf extract. UV–visible absorbance and FTIR confirmed the presence of these nanoparticles. XRD analysis showed that AgO, ZnO NPs, and AgO-ZnO BNPs have a face-centered cubic (FCC) and hexagonal Wurtzite structure, respectively. FESEM and HRTEM results revealed the structure and morphology of synthesized nanoparticles. The average sizes of the AgO, ZnO NPs, and AgO-ZnO BNPs were found to be 77.1, 88, and 95.2 nm and the zeta potentials were −41.6, −35.4, and −67.0 mV respectively. The thermal stability of the nanoparticles was analyzed using TGA and DSC studies. The antioxidant and antibacterial properties of AgO-ZnO BNPs were significantly superior to those of AgO and ZnO nanoparticles. An in vitro cell viability assay conducted after 24 h of exposure to both MNPs and BNPs against HCT-15 cells revealed IC 50 values of 60.07, 105.8, and 29.8 µg/mL, respectively. Similarly, the A549 cell line showed a notable decrease in cell viability, with IC 50 values of 58.5, 116.4, and 55 µg/mL. However, AgO-ZnO BNPs demonstrated superior anticancer activity by MTT assays compared to AgO and ZnO NPs. The anti-ROS properties for both cell lines were assessed using histograms. These findings suggest that the AgO-ZnO BNPs are of greater importance than the monometallic in inducing oxidative stress in cancer cells.