An eco-friendly plant-mediated approach was employed for the synthesis of green zinc oxide nanoparticles (ZnO NPs) and silver-doped zinc oxide nanoparticles (Ag-doped ZnO NPs), using Artemisia Absinthium leaf extract as a reducing and capping agent. Pure ZnO NPs were also synthesized without the leaf extract, and a comparative study between them was conducted. The nanoparticles (NPs) were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), morphological scanning electron microscopy/energy dispersive spectrum (SEM/EDX), and surface area (BET) analysis, and antioxidant and antibacterial activity measurements were conducted. The FTIR analysis showed the absorption peak of the Zn–O bond between 400 and 450 cm−1. The XRD analysis revealed that the ZnO NPs had a hexagonal wurtzite structure with a decrease in particle size from 36.32 to 27.40 to 25.13 nm, and an increase in the BET from 4.003 to 6.032 to 12.151 m2/g for the pure, green, and Ag-doped ZnO NPs, respectively. The field emission scanning electron microscopy (FESEM) imaging revealed the presence of the ZnO NPs. The EDX results showed the zinc and oxygen composition exhibited strong energy signals of 71.28% and 18.12% for zinc and oxygen, respectively. The various characterization techniques used confirmed the formation of the ZnO NPs. The free radical scavenging activities (RSِA%) measured using the 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) assay at different concentrations and times for the pure, green, and Ag-doped ZnO NPs, and ascorbic acid were 25.50, 29.27, 28.56, and 56.7, respectively. The antibacterial activity of the synthesized samples was tested against three types of bacteria, Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, and Pseudomonas aeruginosa ATCC 9027, at different levels (5, 10, 20, and 30 µL), using the hole plate diffusion method. The Ag/ZnO NPs showed more enhanced antibacterial activity than the green ZnO NPs, whereas the pure ZnO NPs showed no antibacterial activity under the same conditions. Comparatively, the antibacterial activity of the Ag-doped ZnO NPs against the test bacteria was found to be higher than that of a commercial gentamycin antibiotic. Ultimately, the present investigation has clearly shown that the differences in the ZnO NPs’ sizes and surface-area-to-volume ratios are responsible for their stronger antibacterial activity.

Recurrent infections after root canal treatments often involve Enterococcus faecalis, a microorganism closely associated with therapy failures due to its biofilm production, survival in nutrient-deprived conditions, and antibiotic tolerance. Essential oils (EOs), which display anti-inflammatory, antimicrobial, and antibacterial properties, exhibit inhibitory effects on the growth of many microorganisms including E. faecalis. This study assessed the in vitro efficacy of combining antibiotics (Gentamicin 1.5mg/ml, Streptomycin 2.5 mg/ml, Ampicillin 5 mg/ml, and Kanamycin 2.5 mg/ml) with Cinnamon (1.25% to 5%) or Clove (25% to 50%) EOs using disk diffusion tests. Disks were treated with EOs-only, antibiotics-only, or EO-antibiotic combinations, placed on BEA agar plates, incubated for 24 hours, and zones of inhibition were measured against E. faecalis. Results showed robust growth inhibition by cinnamon and clove EOs across all tested concentrations. Furthermore, there were synergistic antimicrobial effects when gentamicin, streptomycin and kanamycin were combined with 2.5% and 50% concentrations of cinnamon and clove EOs, respectively, leading to significant growth inhibition of E. faecalis by 139% to 193% compared to using antibiotics or EOs alone. Clove EO showed positive synergism with three antibiotics (gentamicin, streptomycin, and kanamycin) whereas cinnamon EO showed synergism with two antibiotics (streptomycin and kanamycin). These findings suggest that combining cinnamon and clove EOs with aminoglycoside antibiotics can significantly reduce the expansion of E. faecalis compared to antibiotics alone. Further in vivo studies should determine the safety, efficacy, and treatment duration, with the potential to reduce antibiotic dosages and associated toxicity while preventing recurrent infections.