Antibacterial activity of seed aqueous extract of Citrus limon (L.) mediated synthesis ZnO NPs: An impact on Zebrafish (Danio rerio) caudal fin development

Among the different metal oxide nanoparticles, zinc oxide nanoparticles have gained significant importance due to their antibacterial properties against clinically pathogenic bacteria during the organal development. In the present study, biogenic zinc oxide nanoparticles were synthesized using seed extract of Citrus limon by a simple, cost-effective, and green chemistry approach. The synthesized ZnO NPs were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Dynamic Light Scattering, and Scanning Electron Microscopy. Next, the antimicrobial activity of ZnO NPs was tested against clinically pathogenic bacteria, i.e., Pseudomonas fluorescens, Escherichia coli, Enterobacter aerogenes, and Bacillus subtilis. Followed by, ZnO NPs were evaluated for the development of caudal fin in Zebrafish. The UV-Vis spectram result showed a band at 380 nm and FTIR results confirmed the ZnO NPs. The average crystallite size of the ZnO NPs was 52.65 ± 0.5 nm by the Debye Scherrer equation and SEM showed spherical-shaped particles. A zone of inhibition around ZnO NPs applied to P. fluorescens indicates sensitive to ZnO NPs followed by B. subtilis. Among the four different bacterial pathogens, E. aerogenes was the most susceptible compared to the other three pathogens. The calculated sub-lethal concentration of ZnO NPs at 96 h was 153.8 mg/L with a 95% confidence limit ranging from 70.62 to 214.18 mg/L, which was used with partially amputated zebrafish caudal fin growth. A significant (p < 0.5) development (95%) in the amputated caudal fin was detected at 12 days post-amputation. Low concentrated ZnO NPs can reduce developmental malformation. Collectively, suggested results strongly proved that lemon seed-mediated synthesized ZnO NPs had a good pathogenic barrier for bacterial infection during the external organal development for the first time.