Selenium nanoparticles (SeNPs) have advantages over other nanomaterials because of the promising role of selenium in the stabilization of the immune system and activation of the defense response. The use of SeNPs and their supplements not only have pharmacological significance but also boost and prepare the body’s immune system to fight the pathogens. This review summarizes the recent progress in the biogenesis of plant-based SeNPs by using various plant species and the role of secondary metabolites on their biocompatible functioning. Phyto-synthesis of SeNPs results in the synthesis of nanomaterials of various, size, shape and biochemical nature and has advantages over other routine physical and chemical methods because of their biocompatibility, eco-friendly nature and in vivo actions. Unfortunately, the plant-based SeNPs failed to attain considerable attention in the pharmaceutical industry. However, a few studies were performed to explore the therapeutic potential of the SeNPs against various cancer cells, microbial pathogens, viral infections, hepatoprotective actions, diabetic management, and antioxidant approaches. Further, some of the selenium-based drug delivery systems are developed by engineering the SeNPs with the functional ligands to deliver drugs to the targeted sites. This review also provides up-to-date information on the mechanistic actions that the SeNPs adopt to achieve their designated tasks as it may help to develop precision medicine with customized treatment and healthcare for the ailing population.

In the present era, due to the increasing incidence of environmental stresses worldwide, the developmental growth and production of agriculture crops may be restrained. Selenium nanoparticles (SeNPs) have precedence over other nanoparticles because of the significant role of selenium in activating the defense system of plants. In addition to beneficial microorganisms, the use of biogenic SeNPs is known as an environmentally friendly and ecologically biocompatible approach to enhance crop production by alleviating biotic and abiotic stresses. This review provides the latest development in the green synthesis of SeNPs by using the results of plant secondary metabolites in the biogenesis of nanoparticles of different shapes and sizes with unique morphologies. Unfortunately, green synthesized SeNPs failed to achieve significant attention in the agriculture sector. However, research studies were performed to explore the application potential of plant-based SeNPs in alleviating drought, salinity, heavy metal, heat stresses, and bacterial and fungal diseases in plants. This review also explains the mechanistic actions that the biogenic SeNPs acquire to alleviate biotic and abiotic stresses in plants. In this review article, the future research that needs to use plant-mediated SeNPs under the conditions of abiotic and biotic stresses are also highlighted.

In this study, we evaluated bioinspired titanium dioxide nanoparticles (TiO₂ NPs) that elicited biochemical and proteome modifications in wheat plants under the biotic stress caused by Puccinia striiformis f. sp. tritici (Pst). Biosynthesis of TiO₂ NPs was confirmed using UV–Vis spectrophotometry, energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. We found that the nanoparticles with crystalline nature were smaller than 100 nm. The results of FTIR analysis showed the presence of potential functional groups exhibiting O-H, N-H, C-C, and Ti-O stretching. The TiO₂ NPs of different concentrations (20, 40, 60, and 80 mg L⁻¹) were exogenously applied to wheat plants under the biotic stress caused by Pst, which is responsible for yellow stripe rust disease. The results of the assessment of disease incidence and percent disease index displayed time- and dose-dependent responses. The 40 mg L⁻¹ TiO₂ NPs were the most effective in decreasing disease severity. The bioinspired TiO₂ NPs were also evaluated for enzymatic (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), and nonenzymatic metabolites (total proline, phenolic, and flavonoid contents) in wheat plants under stripe rust stress. The 40 mg L⁻¹ TiO₂ NPs were effective in eliciting biochemical modifications to reduce biotic stress. We further evaluated the effects of TiO₂ NPs through gel- and label-free liquid chromatography-mass spectrometry (LC-MS) proteome analysis. We performed proteome analysis of infected wheat leaves and leaves treated with 40 mg L⁻¹ TiO₂ NPs under stripe rust stress. The functional classification of the proteins showed downregulation of proteins related to protein and carbohydrate metabolism, as well as of photosynthesis in plants under biotic stress. An upregulation of stress-related proteins was observed, including the defense mechanisms and primary metabolic pathways in plants treated with 40 mg L⁻¹ TiO₂ NPs under stress. The experimental results showed the potential of applying biogenic TiO₂ NPs to combat fungal diseases of wheat plants and provided insight into the protein expression of plants in response to biotic stress.

The present study was carried out to investigate the beneficial and toxicological effect of plant-based titanium dioxide nanoparticles (TiO ₂ NPs) on the morphophysiological attributes of wheat plants under salinity stress. The biogenesis of titanium dioxide nanoparticles was accomplished by using the extract of Buddleja asiatica L. leaves followed by characterization through UV visible spectroscopy, SEM, FTIR, and EDX. NaCl salt was applied in two different concentrations after 21 days of germination followed by foliar applications of various concentrations of TiO ₂ NPs (20, 40, 60, 80 mg/L) to salinity-tolerant (Faisalabad-08) and salinity-susceptible (NARC-11) wheat varieties after 10–15 days of application of salt stress. Salinity stress showed remarkable decrease in morphophysiological attributes of selected wheat varieties. Magnificent improvement in plant height, dry and fresh weight of plants, shoot and root length, root and shoot fresh and dry weight, number of leaves per plant, RWC, MSI, chlorophyll a and b, and total chlorophyll contents has been observed when 40 mg/L of TiO ₂ NPs was used. However, the plant morphophysiological parameters decreased gradually at higher concentrations (60 and 80 mg/L) in both selected wheat varieties. Therefore, 40 mg/L concentration of TiO ₂ NPs was found most preferable to increase the growth agronomic and physiological attributes of selected wheat varieties under salinity.

Green synthesized cerium oxide nanoparticles (GS-CeO₂ NPs) have a unique size, shape, and biofunctional properties and are decorated with potential biocompatible agents to perform various therapeutic actions, such as antimicrobial, anticancer, antidiabetic, and antioxidant effects and drug delivery, by acquiring various mechanistic approaches at the molecular level. In this review article, we provide a detailed overview of some of these critical mechanisms, including DNA fragmentation, disruption of the electron transport chain, degradation of chromosomal assemblage, mitochondrial damage, inhibition of ATP synthase activity, inhibition of enzyme catalytic sites, disorganization, disruption, and lipid peroxidation of the cell membrane, and inhibition of various cellular pathways. This review article also provides up-to-date information about the future applications of GS-CeONPs to make breakthroughs in medical sectors for the advancement and precision of medicine and to effectively inform the disease diagnosis and treatment strategies.

Citrus greening or huanglongbing (HLB) is commonly known as yellow dragon disease and affects citrus production worldwide. Therefore, it has a significant impact on and deleterious effects in the agro-industrial sector. Significant efforts have been made to combat this disease and mitigate its destructive impact on citrus production, but still, there is no effective biocompatible treatment available to control HLB disorder. This study is considered the first biocompatible approach to evaluate the potential of phytogenic selenium nanoparticles (SeNPs) to improve the health of HLB-infected ‘Kinnow’ mandarin plants. Polymerase chain reactions (PCRs) with specific primers were used to detect HLB disease in ‘Kinnow’ mandarin plants, and PCR products were sequenced to identify Candidatus Liberibacter asiaticus (CLas), and accession numbers for CLas1 and CLas2, MZ851933 and MZ851934, respectively, were obtained. SeNPs were synthesized by using Allium sativum L. clove extract as a reducing, capping, and stabilizing agent and various techniques such as UV-visible spectrophotometry, energy dispersive X-rays, scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD) were used to confirm the biogenesis of SeNPs. Different concentrations of SeNPs (25, 50, 75, and 100 mg L⁻¹) were exogenously applied to HLB-infected ‘Kinnow’ mandarin plants and obtained spectacular results. The obtained results from the current study proved that 75 mg L⁻¹ of SeNPs was most effective to improve the chlorophyll, carotenoids, relative water content (RWC), membrane stability index (MSI), total soluble sugar (TSS), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), total flavonoid content (TFC), and total phenolic content (TPC) and significant decrease was observed in hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and proline (PRO) contents of HLB-infected ‘Kinnow’ mandarin plants as compared to untreated diseased citrus plants. In conclusion, these results allow us to synthesize the SeNPs formulation as a promising management strategy to treat the HLB disease in citrus plants.