ZnO Nanoparticles Obtained by Green Synthesis as an Alternative to Improve the Germination Characteristics of L. esculentum

Revolutionizing agriculture: Harnessing nano-innovations for sustainable farming and environmental preservation

The agricultural sector is currently confronted with a significant crisis stemming from the rapid changes in climate patterns, declining soil fertility, insufficient availability of essential macro and micronutrients, excessive reliance on chemical fertilizers and pesticides, and the presence of heavy metals in soil. These numerous challenges pose a considerable threat to the agriculture industry. Furthermore, the exponential growth of the global population has led to a substantial increase in food consumption, further straining agricultural systems worldwide. Nanotechnology holds great promise in revolutionizing the food and agriculture industry, decreasing the harmful effects of agricultural practices on the environment, and improving productivity. Nanomaterials such as inorganic, lipid, and polymeric nanoparticles have been developed for increasing productivity due to their unique properties. Various strategies can enhance product quality, such as the use of nano-clays, nano zeolites, and hydrogel-based materials to regulate water absorption and release, effectively mitigating water scarcity. The production of nanoparticles can be achieved through various methods, each of which has its own unique benefits and limitations. Among these methods, chemical synthesis is widely favored due to the impact that various factors such as concentration, particle size, and shape have on product quality and efficiency. This review provides a detailed examination of the roles of nanotechnology and nanoparticles in sustainable agriculture, including their synthetic methods, and presents an analysis of their associated advantages and disadvantages. To date, there are serious concerns and awareness about healthy agriculture and the production of healthy products, therefore the development of nanotech-enabled devices that act as preventive and early warning systems to identify health issues, offering remedial measures is necessary.

Seed Priming with Zinc Oxide Nanoparticles to Enhance Crop Tolerance to Environmental Stresses

Drastic climate changes over the years have triggered environmental challenges for wild plants and crops due to fluctuating weather patterns worldwide. This has caused different types of stressors, responsible for a decrease in plant life and biological productivity, with consequent food shortages, especially in areas under threat of desertification. Nanotechnology-based approaches have great potential in mitigating environmental stressors, thus fostering a sustainable agriculture. Zinc oxide nanoparticles (ZnO NPs) have demonstrated to be biostimulants as well as remedies to both environmental and biotic stresses. Their administration in the early sowing stages, i.e., seed priming, proved to be effective in improving germination rate, seedling and plant growth and in ameliorating the indicators of plants' well-being. Seed nano-priming acts through several mechanisms such as enhanced nutrients uptake, improved antioxidant properties, ROS accumulation and lipid peroxidation. The target for seed priming by ZnO NPs is mostly crops of large consumption or staple food, in order to meet the increased needs of a growing population and the net drop of global crop frequency, due to climate changes and soil contaminations. The current review focuses on the most recent low-cost, low-sized ZnO NPs employed for seed nano-priming, to alleviate abiotic and biotic stresses, mitigate the negative effects of improper storage and biostimulate plants' growth and well-being. Taking into account that there is large variability among ZnO NPs and that their chemico-physical properties may play a role in determining the efficacy of nano-priming, for all examined cases, it is reported whether the ZnO NPs are commercial or lab prepared. In the latter cases, the preparation conditions are described, along with structural and morphological characterizations. Under these premises, future perspectives and challenges are discussed in relation to structural properties and the possibility of ZnO NPs engineering.

Development and Evaluation of Zinc and Iron Nanoparticles Functionalized with Plant Growth-Promoting Rhizobacteria (PGPR) and Microalgae for Their Application as Bio-Nanofertilizers

Micronutrient deficiencies are widespread and growing global concerns. Nanoscale nutrients present higher absorption rates and improved nutrient availability and nutrient use efficiency. Co-application of nanofertilizers (NFs) with biological agents or organic compounds increases NF biocompatibility, stability, and efficacy. This study aimed to develop and evaluate zinc and iron bio-nanofertilizers formulated with plant growth-promoting rhizobacteria (PGPR) and microalgae. Nanoparticles (NPs) were synthesized with the co-precipitation method and functionalized with Pseudomonas species and Spirulina platensis preparation. NPs were characterized and evaluated on seed germination, soil microbial growth, and early plant response under seedbed conditions. NPs corresponded to zinc oxide (ZnO; 77 nm) and maghemite (γ-Fe2O3; 68 nm). Functionalized nanoparticles showed larger sizes, around 145-233 nm. The seedling vigor index of tomato and maize was significantly increased (32.9-46.1%) by bacteria-functionalized ZnO- and γ-Fe2O3-NPs at 75 ppm. NFs at 250 and 75 ppm significantly increased bacterial growth. NFs also improved early plant growth by increasing plant height (14-44%), leaf diameter (22-47%), and fresh weight (46-119%) in broccoli and radish, which were mainly influenced by bacteria capped ZnO- and γ-Fe2O3-NPs at 250 ppm. Beneficial effects on plant growth can be attributed to the synergistic interaction of the biological components and the zinc and iron NPs in the bio-nanofertilizers.

Green nanotechnology advances: green manufacturing of zinc nanoparticles, characterization, and foliar application on wheat and antibacterial characteristics using Mentha spicata (mint) and Ocimum basilicum (basil) leaf extracts

Due to their distinctive characteristics and widespread application across all scientific disciplines, nanoparticles have attracted a lot of attention in the current millennium. Green synthesis of ZnO-NPs is gaining a lot of interest at the moment due to a number of its advantages over traditional methods, including being quicker, less expensive, and more environmentally friendly. In the current study, two distinct plant extracts are used to quickly, cheaply, and environmentally friendly synthesize zinc oxide nanoparticles (ZnO-NPs). Mint (Mentha spicata) and basil (Ocimum basilicum) were the plants employed in this study as stabilizing agents to synthesize ZnO-NPs with a green chemistry approach. The innovative aspect of the study is the use of mint and basil extracts in the conversion of zinc chloride to zinc oxide and then determining the effect of these two types of nanoparticles produced by green synthesis on the growth parameters of the plant when they reach the plants by foliar spraying and their uptake by plants and evaluating the antibacterial properties of these nanoparticles. The physical properties of the produced nanoparticles were investigated using XRD, SEM, and FTIR. Moreover, Escherichia coli and Staphylococcus aureus were used to demonstrate the antibacterial properties of ZnO-NPs against both gram-positive and gram-negative bacteria, respectively. Synthesized ZnO-NPs were also given as foliar treatment in order to determine Zn⁺² uptake by plants and potential toxic effects on the growth of wheat. The shape of ZnO-NPs was triangular, as revealed by SEM analysis. In the X-ray diffraction study, strong and clearly discernible sharp peaks were seen, with an average size of 24.5 nm for M-ZnO-NPs and 26.7 nm for B-ZnO-NPs determined using Scherrer's formula. The phytoconstituents of the plant extract served as capping/stabilizing agents during the synthesis of ZnO-NPs, as demonstrated by Fourier transform-infrared spectroscopy. The produced nanoparticles were applied to the green parts of wheat plants by spraying, and the development of the plants and the change of zinc uptake were investigated. At the same time, the effect of these three types of nanoparticles on the germination of wheat seeds in the soil medium containing these nanoparticles was investigated. According to experimental results, M-ZnO-NPs (produced from mint) and B-ZnO-NPs (produced from basil) improved the germination percentage of wheat at 400 mg/L concentration (100%), while raw ZnO-NPs showed 90% germination at the same concentration. When the Zn⁺² uptake of the plant by the leaves depending on the Zn⁺² concentration in the environment after spraying was examined, it was determined that the Zn⁺² uptake of the plants increased due to the increase in the applied Zn⁺² concentration. The highest Zn⁺² uptake of the plant was determined as 50, 25, and 50 mg/L for M-ZnO-NP, B-ZnO-NPs, and raw ZnO-NPs, respectively. Therefore, it has been determined that plant growth varies depending on the type and concentration of ZnO-NPs, and therefore, if foliar nanoparticle applications are made to wheat, the threshold concentrations, sizes, and types of ZnO-NPs should be carefully evaluated. In addition, antibacterial properties results showed that S. aureus was more sensitive to all three types of ZnO-NPs than E. coli.

Husk-like Zinc Oxide Nanoparticles Induce Apoptosis through ROS Generation in Epidermoid Carcinoma Cells: Effect of Incubation Period on Sol-Gel Synthesis and Anti-Cancerous Properties

This study effectively reports the influence of experimental incubation period on the sol-gel production of husk-like zinc oxide nanoparticles (ZNPs) and their anti-cancerous abilities. The surface morphology of ZNPs was studied with the help of SEM. With the use of TEM, the diameter range of the ZNPs was estimated to be ~86 and ~231 nm for ZNP^A and ZNP^B, prepared by incubating zinc oxide for 2 and 10 weeks, respectively. The X-ray diffraction (XRD) investigation showed that ZNPs had a pure wurtzite crystal structure. On prolonging the experimental incubation, a relative drop in aspect ratio was observed, displaying a distinct blue-shift in the UV-visible spectrum. Furthermore, RBC lysis assay results concluded that ZNP^A and ZNP^B both demonstrated innoxious nature. As indicated by MTT assay, reactive oxygen species (ROS) release, and chromatin condensation investigations against the human epidermoid carcinoma (HEC) A431 cells, ZNP^B demonstrated viable relevance to chemotherapy. Compared to ZNP^B, ZNP^A had a slightly lower IC₅₀ against A431 cells due to its small size. This study conclusively describes a simple, affordable method to produce ZNP nano-formulations that display significant cytotoxicity against the skin cancer cell line A431, suggesting that ZNPs may be useful in the treatment of cancer.