The realm of agriculture has to confront an expansive gamut of challenges including climatic change, stagnant crop yield and the increasing resistance against pesticides. The explicit usage of agrochemicals along with the introduction of high yielding varieties and genetically modified seeds has already directed the agricultural systems towards a state of saturation in production. Therefore, the increasing need of sustainability demands the involvement of advanced nanotechnological approaches for enhancing crop productivity. Enhanced solubility, absorption and target specificity of nannofertilizers prepared using materials like silver, copper, gold and oxides of zinc and iron could address some of nutritional challenges. Nanopesticides such as chitosan loaded with spino sad, silica encapsulating fipronil and sodium alginate enclosing imidacloprid find applications in pest control while fluorescence nanosensor, carbon and graphene nanodots are exploited in herbicide and heavy metal detection. Nanofilteration involving grapheme, cellulose and cyclodextrin for removal of salt, heavy metals and organic pollutants, respectively, could significantly improve quality of hard and waste water making it suitable for irrigation.

The aqueous Trigonella foenum-graecum L. leaf extract belonging to variety HM 444 was used as reducing agent for silver nanoparticles (AgNPs) synthesis. UV–Visible spectroscopy, Particle size analyser (PSA), Field emission scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (FESEM-EDX) and High-resolution transmission electron microscopy (HRTEM) were used to characterize AgNPs. Selected area electron diffraction (SAED) confirmed the formation of metallic Ag. Fourier Transform Infrared Spectroscopy (FTIR) was done to find out the possible phytochemicals responsible for stabilization and capping of the AgNPs. The produced AgNPs had an average particle size of 21 nm, were spherical in shape, and monodispersed. It showed catalytic degradation of Methylene blue (96.57%, 0.1665 ± 0.03 min−1), Methyl orange (71.45%, 0.1054 ± 0.002 min−1), and Rhodamine B (92.72%, 0.2004 ± 0.01 min−1). The produced AgNPs were excellent solid bio-based sensors because they were very sensitive to Hg2+ and Fe3+ metal ions with a detection limit of 11.17 µM and 195.24 µM, respectively. From the results obtained, it was suggested that aqueous leaf extract demonstrated a versatile and cost-effective method and should be utilized in future as green technology for the fabrication of nanoparticles.

Silver nanoparticles (AgNPs) were fabricated using Trigonella foenum-graceum L. leaf extract, belonging to the variety HM 425, as leaf extracts are a rich source of phytochemicals such as polyphenols, flavonoids, and sugars, which function as reducing, stabilizing, and capping agents in the reduction of silver ions to AgNPs. These phytochemicals were quantitatively determined in leaf extracts, and then, their ability to mediate AgNP biosynthesis was assessed. The optical, structural, and morphological properties of as-synthesized AgNPs were characterized using UV-visible spectroscopy, a particle size analyzer (PSA), FESEM (field emission scanning electron microscopy), HRTEM (high-resolution transmission electron microscopy), and FTIR (Fourier transform infrared spectroscopy). HRTEM analysis demonstrated the formation of spherically shaped AgNPs with a diameter of 4–22 nm. By using the well diffusion method, the antimicrobial potency of AgNPs and leaf extract was evaluated against microbial strains of Staphylococcus aureus, Xanthomonas spp., Macrophomina phaseolina, and Fusarium oxysporum. AgNPs showed significant antioxidant efficacy with IC50 = 426.25 µg/mL in comparison to leaf extract with IC50 = 432.50 µg/mL against 2,2-diphenyl-1-picrylhydrazyl (DPPH). The AgNPs (64.36 mg AAE/g) demonstrated greater total antioxidant capacity using the phosphomolybdneum assay compared to the aqueous leaf extract (55.61 mg AAE/g) at a concentration of 1100 μg/mL. Based on these findings, AgNPs may indeed be useful for biomedical applications and drug delivery systems in the future.

Nanotechnology has become the foremost promising and rising field of analysis as a result of its applications in numerous fields. Development of consistent and greener ways for the synthesis of nanoparticles could be a dynamic step in the field of nanotechnology. To avoid the emergence of dangerous by-products, many attempts have been made in recent years to develop environment friendly methods. “Green” synthesis is a consistent, sustainable, and environment friendly method for the synthesis of an enormous range of nanoparticles. Green synthesis is seen as an important tool to reduce the harmful effects of traditional nanoparticle synthesis methods commonly used in laboratories and industries. Nanoparticles exhibit unique chemical and physical properties that are useful in various fields. Among metallic nanoparticles, silver nanoparticles have become a research hotspot due to their wide range of applications. Silver nanoparticles are important because of their exceptional chemical, physical, and biological properties. Because of these unique characteristics, silver nanoparticles have numerous applications and are used as antifungal, antiviral, and antibacterial agents. They have an excellent catalytic effect on dye degradation, are very good antioxidants, and can be used to treat various diseases and exhibit wound-healing activities. The current review complies with the database of green synthesis of silver nanoparticles using plant extracts, bacteria, and fungi, which have potential applications in fields of science, health, textiles, food packaging, agriculture, and environment. The review also highlights the application of silver nanoparticles as antimicrobial, antibacterial, antiviral, and antifungal agents. The knowledge on silver nanoparticle production conditions, properties, molecular mechanisms, and applications will be of great help for researchers to explore more applications of nanoparticles in fields that are still untouched.

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