In Situ Green Synthesis of Co 3 O 4 @ZnO Core-Shell Nanoparticles Using Datura stramonium Leaf Extract: Antibacterial and Antioxidant Studies.

Investigating and synthesizing potent antibacterial NPs using biological methods is highly preferred, and it involves nontoxic, cost-effective, and environmentally friendly chemicals and methods. Antibiotic drug resistance and oxidative stress have become a serious public health issue worldwide. Hence, the key objective of this study was to biologically synthesize and characterize the potent antibacterial Co 3 O 4 @ZnO core-shell nanoparticles for the antibacterial application. The radical scavenging ability of green synthesized Co 3 O 4 @ZnO core-shell nanoparticles was also determined. In this study, Co 3 O 4 @ZnO core-shell nanoparticles (CZCS NPs) have been synthesized using three different core to shell materials ratios of Co 3 O 4 to ZnO (0.5 : 0.25 CZCS (1), 0.5 : 0.5 CZCS (2), and 0.5 : 0.75 M CZCS (3)) by employing Datura stramonium leaf extract. The polycrystalline nature of Co 3 O 4 @ZnO core-shell nanoparticles was investigated using the XRD and SAED characterization techniques. The investigated nanostructure of Co 3 O 4 @ZnO core-shell nanoparticles appeared with Co 3 O 4 as the core and ZnO as an outer shell. Additionally, a variety of physicochemical properties of the nanoparticles were determined using various characterization techniques. The average crystallite sizes of CZCS (1), CZCS (2), and CZCS (3) were found to be 24 ± 1.4, 22 ± 1.5, and 25 ± 1.5 nm, respectively. The band gap energy values for CZCS (1), CZCS (2), and CZCS (3) determined from the UV-DRS data were found to be 2.75, 2.76, and 2.73 eV, respectively. The high inhibition activities against S. aureus , S. pyogenes , E. coli , and P. aeruginosa bacterial strains were obtained for the small size CZCS (2) nanoparticles at the concentration of 100 mg/mL with 22 ± 0.34, 19 ± 0.32, 18 ± 0.45, and 17 ± 0.32 mm values, respectively. The high inhibition performance of CZCS (2) nanoparticles against Gram-positive and Gram-negative bacteria which is even above the control drug ampicillin is because of its small size and synergistic effect. The percentage scavenging activity of Co 3 O 4 @ZnO core-shell nanoparticles was also studied and CZCS (2) nanoparticles showed a good scavenging capacity (86.87%) at 500  μ g/mL with IC50 of 209.26  μ g/mL.