Biosynthesis and Characterization of ZnO Nanoparticles Using Citrus reticulata Peel Followed by Photocatalytic,...

ZnO nanoparticles (NPs) have garnered significant attention due to their remarkable multifunctionality, particularly in biomedical and environmental applications.

The study synthesized ZnO NPs using Citrus reticulata Blanco peel extracts. The structural, morphological, and optical properties of ZnO NPs have been analyzed. The antibacterial and antioxidant activity of ZnO NPs was assessed using disk diffusion and DPPH scavenging method, respectively. Molecular docking was further conducted to support our experiments. In addition, the photocatalytic activity of biosynthesized ZnO NPs was tested using methylene blue (MB) dye.

X-ray diffraction (XRD) results indicate that NPs possess a hexagonal wurtzite crystal structure. The crystallite size of the NPs was 30.12 nm. Field emission scanning electron microscopy (FESEM) analysis revealed quasi-spherical and rod-shaped ZnO NPs. Energy Dispersive X-ray (EDX) showed that Zn and O were 86.59% and 13.41% of the total weight, respectively. Optical analysis revealed that the absorption edge was at 373 nm and the band gap was 3.09 eV for ZnO NPs. Moreover, the maximum zone of inhibition was measured at 16.17 ± 0.72 mm, 10.5 ± 0.28 mm, 16.17 ± 0.44 mm, and 12.17 ± 0.44 mm against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Shigella flexneri, respectively. Compared with BHT, ZnO NPs showed promising antioxidant performance with an IC₅₀ value of 149.01 µg/mL. The photocatalytic efficiency of the ZnO NPs was 6.8%, 8.42%, and 10% after 30, 60, and 90 minutes, respectively. Hesperidin, naringin, rutin, and tangeritin, the principal constituents of C. reticulata peel, also showed higher and promising binding affinities against the receptors, with remarkable results compared to the standard in molecular docking analysis. The ADMET analysis also demonstrated that ZnO NPs exhibited low probabilities of hepatotoxicity (3%), nephrotoxicity (20%), and respiratory toxicity (20%), with moderate neurotoxicity (52%).

In summary, this study revealed morpho-structural features of green synthesized ZnO NPs and their photodegradation efficiency and bioactivity.