Catharanthus roseus-assisted bio-fabricated zinc oxide nanoparticles for promising antibacterial potential against Klebsiella pneumoniae

This study emphasized on the synthesis of zinc oxide nanoparticles (ZnO NPs) in an environmentally friendly manner from the extract of Catharanthus roseus leaves and its antibacterial assessment against the pneumonia-causing pathogen Klebsiella pneumoniae. This simple and convenient phytosynthesis approach is found to be beneficial over conventional methods, wherein plants serve as excellent reducing, capping, and stabilizing agents that enables the formation of ZnO NPs without the use of harmful chemicals. The formation of ZnO NPs was confirmed through several characterization techniques such as UV-visible spectroscopy, XRD, FT-IR, SEM, HR-TEM, and EDX. XRD analysis revealed high polycrystallinity with crystallite size of approximately 13 nm. SEM and HR-TEM revealed the hexagonal structure of ZnO NPs with the particle size range of 20-50 nm. The EDX shows the elemental purity without any impurity. Furthermore, the antibacterial efficacy by the technique of disc diffusion exhibited clear inhibition zones in ZnO NPs-treated discs. In addition, 125 µg/mL of ZnO NP concentration showed minimum inhibition by the microbroth dilution method. The potent inhibitory activity was further validated with trypan blue dye exclusion and fluorescence microscopy. Finally, SEM examination confirmed the efficient antibacterial potential of ZnO NPs through disruption of the intact morphology of Klebsiella pneumoniae.

Biofabrication of zinc oxide nanoparticles from Melia azedarach and its potential in controlling soybean seed-borne phytopathogenic fungi

Present study, report the biofabrication of zinc oxide nanoparticles from aqueous leaf extract of Melia azedarach (MaZnO-NPs) through solution combustion method and their novel application in preventing the growth of seed-borne fungal pathogens of soybean (Cladosporium cladosporioides and Fusarium oxysporum). The standard blotter method was employed to isolate fungi and was identified through molecular techniques. The characterization of MaZnO-NPs was carried out by UV–Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM). The physicochemical characterization confirmed the particles were of high purity and nano size (30–40 nm) with a hexagonal shape. The synthesized MaZnO-NPs inhibited the growth of C. cladosporioides and F. oxysporum in a dose dependent manner. Biomass, ergosterol, lipid peroxidation, intracellular reactive oxygen species and membrane integrity determination upon MaZnO-NPs treatment offered significant activities there by confirming the mechanism of action against the test pathogens. In conclusion, due to the effectiveness of MaZnO-NPs in controlling the growth of C. cladosporioides and F. oxysporum, the synthesized MaZnO-NPs provides insight towards their potential application in agriculture and food industries.

Cinnamomum verum Bark Extract Mediated Green Synthesis of ZnO Nanoparticles and Their Antibacterial Potentiality

Cinnamomum verum plant extract mediated propellant chemistry route was used for the green synthesis of zinc oxide nanoparticles. Prepared samples were confirmed for their nano regime using advanced characterization techniques such as powder X-ray diffraction and microscopic techniques such as scanning electron microscopy and transmission electron microscopy. The energy band gap of the green synthesized zinc oxide (ZnO)-nanoparticles (NPs) were found between 3.25-3.28 eV. Fourier transmission infrared spectroscopy shows the presence of Zn-O bond within the wave number of 500 cm-1. SEM images show the specific agglomeration of particles which was also confirmed by TEM studies. The green synthesized ZnO-NPs inhibited the growth of Escherichia coli and Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 125 µg mL-1 and 62.5 µg mL-1, respectively. The results indicate the prepared ZnO-NPs can be used as a potential antimicrobial agent against harmful pathogens.

Biofabrication of Zinc Oxide Nanoparticles With Syzygium aromaticum Flower Buds Extract and Finding Its Novel Application in Controlling the Growth and Mycotoxins of Fusarium graminearum

Fusarium graminearum is a leading plant pathogen that causes Fusarium head blight, stalk rot, and Gibberella ear rot diseases in cereals and posing the immense threat to the microbiological safety of the food. Herein, we report the green synthesis of zinc oxide nanoparticles from Syzygium aromaticum (SaZnO NPs) flower bud extract by combustion method and investigated their application for controlling of growth and mycotoxins of F. graminearum. Formation of SaZnO NPs was confirmed by spectroscopic methods. The electron microscopic (SEM and TEM) analysis revealed the formation of triangular and hexagonal shaped SaZnO NPs with size range 30-40 nm. The synthesized SaZnO NPs reduced the growth and production of deoxynivalenol and zearalenone of F. graminearum in broth culture. Further analysis revealed that treatment of mycelia with SaZnO NPs resulted in the accumulation of ROS in the dose-dependent manner. Also, SaZnO NPs treatment enhanced lipid peroxidation, depleted ergosterol content, and caused detrimental damage to the membrane integrity of fungi. Moreover, SEM observations revealed that the presence of diverged micro-morphology (wrinkled, rough and shrank surface) in the macroconidia treated with SaZnO NPs. Taken together, SaZnO NPs may find a potential application in agriculture and food industries due to their potent antifungal activity.