A review on metal-based nanoparticles and their toxicity to beneficial soil bacteria and fungi

Nanotechnology in sustainable agriculture: A double-edged sword

Nanotechnology is a rapidly developing discipline that has the potential to transform the way we approach problems in a variety of fields, including agriculture. The use of nanotechnology in sustainable agriculture has gained popularity in recent years. It has various applications in agriculture, such as the development of nanoscale materials and devices to boost agricultural productivity, enhance food quality and safety, improve the efficiency of water and nutrient usage, and reduce environmental pollution. Nanotechnology has proven to be very beneficial in this field, particularly in the development of nanoscale delivery systems for agrochemicals such as pesticides, fertilizers, and growth regulators. These nanoscale delivery technologies offer various benefits over conventional delivery systems, including better penetration and distribution, enhanced efficacy, and lower environmental impact. Encapsulating agrochemicals in nanoscale particles enables direct delivery to the targeted site in the plant, thereby reducing waste and minimizing off-target effects. Plants are fundamental building blocks of all ecosystems and evaluating the interaction between nanoparticles (NPs) and plants is a crucial aspect of risk assessment. This critical review therefore aims to provide an overview of the latest advances regarding the positive and negative effects of nanotechnology in agriculture. It also explores potential future research directions focused on ensuring the safe utilization of NPs in this field, which could lead to sustainable development. © 2024 Society of Chemical Industry.

Unveiling the Impact of Eco-Friendly Synthesized Nanoparticles on Vegetative Growth and Gene Expression in Pelargonium graveolens and Sinapis alba L

Nanoscale geranium waste (GW) and magnesium nanoparticle/GW nanocomposites (Mg NP/GW) were prepared using green synthesis. The Mg NP/GW samples were subjected to characterization using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR-FT). The surface morphology of the materials was examined using a scanning electron microscope (SEM), and their thermal stability was assessed through thermal gravimetric analysis (TG). The BET-specific surface area, pore volume, and pore size distribution of the prepared materials were determined using the N2 adsorption-desorption method. Additionally, the particle size and zeta potentials of the materials were also measured. The influence of the prepared nanomaterials on seed germination was intensively investigated. The results revealed an increase in seed germination percent at low concentrations of Mg NP/GWs. Upon treatment with Mg NP/GW nanoparticles, a reduction in the mitotic index (MI) was observed, indicating a decrease in cell division. Additionally, an increase in chromosomal abnormalities was detected. The efficacy of GW and Mg NP/GW nanoparticles as new elicitors was evaluated by studying their impact on the expression levels of the farnesyl diphosphate synthase (FPPS1) and geranylgeranyl pyrophosphate (GPPS1) genes. These genes play a crucial role in the terpenoid biosynthesis pathway in Sinapis alba (S. alba) and Pelargonium graveolens (P. graveolens) plants. The expression levels were analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis. The qRT-PCR analysis of FPPS and GPPS gene expression was performed. The outputs of FPPS1 gene expression demonstrated high levels of mRNA in both S. alba and P. graveolens with fold changes of 25.24 and 21.68, respectively. In contrast, the minimum expression levels were observed for the GPPS1 gene, with fold changes of 11.28 and 6.48 in S. alba and P. graveolens, respectively. Thus, this study offers the employment of medicinal plants as an alternative to fertilizer usage resulting in promoting environmental preservation, optimal waste utilization, reducing water consumption, and cost reduction.

Nanomaterials in the environment and their pragmatic voyage at various trophic levels in an ecosystem

In the development of nanotechnology, nanomaterials (NMs) have a huge credential in advancing the existing follow-ups of analytical and diagnosis techniques, drug designing, agricultural science, electronics, cosmetics, sports, textiles and water purification. However, NMs have also grasped attention of researchers onto their toxicity. In the present review, initially the development of notable NMs such as metal and metal-oxide nanoparticles (NPs), magnetic NPs, carbon-based NMs and quantum dots intended to be commercialized along with their applications are discussed. This is followed by the current scenario of NMs in the environment to widen the outlook on the concentration of NPs in the environmental compartments and the frequency of organism exposed to NPs at varied trophic levels. In order to understand the physiochemical and morphological significance of NPs in exhibiting toxicity, fate of NPs in the environment is briefly deliberated. This is further geared-up to glance in-sightedly on the organisms starting from primary producer to primary consumer, secondary consumer, tertiary consumer and decomposers encountering NPs in their habitual niche. The state of NPs to which organisms are exposed, mechanism of NP uptake and toxicity, anomalies faced at each trophic level, concentration of NPs that is liable to cause toxicity and, biotransfer of NPs to the next generation and trophic level are detailed. Finally, the future prospects on bioaccumulation and biomagnification of NP-based products are conversed. Thus, the review would be noteworthy in unveiling the significance of NPs in forthcoming years combined with threat towards each organism in an ecosystem.

Nanoparticles and root traits: mineral nutrition, stress tolerance and interaction with rhizosphere microbiota

MAIN CONCLUSION

This review article highlights a broader perspective of NPs and plant-root interaction by focusing on their beneficial and deleterious impacts on root system architecture (RSA). The root performs a vital function by securing itself in the soil, absorbing and transporting water and nutrients to facilitate plant growth and productivity. In dicots, the architecture of the root system (RSA) is markedly shaped by the development of the primary root and its branches, showcasing considerable adaptability in response to changes in the environment. For promoting agriculture and combating global food hunger, the use of nanoparticles (NPs) may be an exciting option, for which it is essential to understand the behaviour of plants under NPs exposure. The nature of NPs and their physicochemical characteristics play a significant role in the positive/negative response of roots and shoots. Root morphological features, such as root length, root mass and root development features, may regulated positively/negatively by different types of NPs. In addition, application of NPs may also enhance nutrient transport and soil fertility by the promotion of soil microorganisms including plant growth-promoting rhizobacteria (PGPRs) and also soil enzymes. Interestingly the interaction of nanomaterials (NMs) with rhizospheric bacteria can enhance plant development and soil health. However, some studies also suggested that the increased use of several types of engineered nanoparticles (ENPs) may disrupt the equilibrium of the soil-root interface and unsafe morphogenesis by causing the browning of roots and suppressing the growth of root and soil microbes. Thus, this review article has sought to compile a broader perspective of NPs and plant-root interaction by focusing on their beneficial or deleterious impacts on RSA.

Nano molybdenum trioxide-mediated enhancement of soybean yield through improvement of rhizosphere soil molybdenum bioavailability for nitrogen-fixing microbial recruitment

Molybdenum (Mo) plays a pivotal role in the growth and nitrogen-fixing process of plants mediated by rhizobia. However, the influence of nano‑molybdenum trioxide (MoO3NPs) on soybean growth, rhizosphere bioavailable Mo, and nitrogen-fixing microorganisms remains underexplored. Here, we report that compared with that of ionic Mo and bulk MoO3, the utilization of MoO3NPs (specifically NPs0.05 and NPs0.15) significantly boosted the available Mo content in the rhizosphere soil throughout the seedling (by 21.64 %-101.38 %), podding (by 54.44 %-68.89 %), and mature stage (by 34.41 %-to 45.71 %) of soybean growth. Furthermore, both NPs0.05 and NPs0.15 treatments maintained consistently higher levels of acid-extractable Mo, reducible Mo, and oxidizable Mo across these stages, which facilitated stable conversion and supply of bioavailable Mo. Within the rhizosphere soil, NPs0.05 and NPs0.15 treatments resulted in the highest relative abundance of Rhizobiales and Bradyrhizobium genera, and significantly promoted the colonization of nitrogen-fixing microorganisms, thereby increasing the content of nitrate nitrogen (NO3--N) by 8.69 % and 7.72 % and ammonium nitrogen (NH4+-N) by 44.75 % and 17.55 %, respectively. Ultimately, these effects together contributed to 107.17 % and 84.00 % increment in soybean yield by NPs0.05 and NPs0.15 treatments, respectively. In summary, our findings underscore the potential of employing MoO3NPs to promote plant growth and maintain soil nitrogen cycling, indicating distinct advantages of MoO3NPs over ionic Mo and bulk MoO3.

Metallic nanoparticles and photosynthesis organisms: Comprehensive review from the ecological perspective

This review presents a comprehensive analysis of the ecological implications of metallic nanoparticles (MNPs) on photosynthetic organisms, particularly plants and algae. We delve into the toxicological impacts of various MNPs, including gold, silver, copper-based, zinc oxide, and titanium dioxide nanoparticles, elucidating their effects on the growth and health of these organisms. The article also summarizes the toxicity mechanisms of these nanoparticles in plants and algae from previous research, providing insight into the cellular and molecular interactions that underpin these effects. Furthermore, it discusses the reciprocal interactions between different types of MNPs, their combined effects with other metal contaminants, and compares the toxicity between MNPs with their counterpart. This review highlights the urgent need for a deeper understanding of the environmental impact, considering their escalating use and the potential risks they pose to ecological systems, especially in the context of photosynthetic organisms that are vital to ecosystem health and stability.

Toxicological effects of nanoparticles in plants: Mechanisms involved at morphological, physiological, biochemical and molecular levels

The rapid advancement of nanotechnology has led to unprecedented innovations across diverse industries, including pharmaceuticals, agriculture, cosmetics, electronics, textiles, and food, owing to the unique properties of nanoparticles. The extensive production and unregulated release of synthetic nanoparticles may contribute to nanopollution within the ecosystem. In the agricultural sector, nanotechnology is increasingly utilized to improve plant productivity, enhance resistance to stressors, and reduce the usage of chemicals. However, the uncontrolled discharge of nanoparticles into the natural environment raises concerns regarding possible plant toxicological impacts. The review focuses on the translocation of these particles within the plants, emphasizing their phytotoxicological effects at morphological, physiological, biochemical, and molecular levels. Eventhough the beneficial aspects of these nanoparticles are evident, excessive usage of nanoparticles at higher concentrations may lead to potential adverse effects. The phytotoxicity resulting from excessive amounts of nanoparticles affects seed germination and biomass production, disrupts the photosynthesis system, induces oxidative stress, impacts cell membrane integrity, alters gene expression, causes DNA damage, and leads to epigenetic variations in plants. Nanoparticles are found to directly associate with the cell membrane and cell organelles, leading to the dissolution and release of toxic ions, generation of reactive oxygen species (ROS) and subsequent oxidative stress. The present study signifies and accumulates knowledge regarding the application of nanoparticles in agriculture and illustrates a clear picture of their possible impacts on plants and soil microbes, thereby paving the way for future developments in nano-agrotechnology. The review concludes by addressing current challenges and proposing future directions to comprehend and mitigate the possible biological risks associated with nanoparticles in agriculture.

Synergistic interactions of nanoparticles and plant growth promoting rhizobacteria enhancing soil-plant systems: a multigenerational perspective

Sustainable food security and safety are major concerns on a global scale, especially in developed nations. Adverse agroclimatic conditions affect the largest agricultural-producing areas, which reduces the production of crops. Achieving sustainable food safety is challenging because of several factors, such as soil flooding/waterlogging, ultraviolet (UV) rays, acidic/sodic soil, hazardous ions, low and high temperatures, and nutritional imbalances. Plant growth-promoting rhizobacteria (PGPR) are widely employed in in-vitro conditions because they are widely recognized as a more environmentally and sustainably friendly approach to increasing crop yield in contaminated and fertile soil. Conversely, the use of nanoparticles (NPs) as an amendment in the soil has recently been proposed as an economical way to enhance the texture of the soil and improving agricultural yields. Nowadays, various research experiments have combined or individually applied with the PGPR and NPs for balancing soil elements and crop yield in response to control and adverse situations, with the expectation that both additives might perform well together. According to several research findings, interactive applications significantly increase sustainable crop yields more than PGPR or NPs alone. The present review summarized the functional and mechanistic basis of the interactive role of PGPR and NPs. However, this article focused on the potential of the research direction to realize the possible interaction of PGPR and NPs at a large scale in the upcoming years.

Metallic nanoparticle actions on the outer layer structure and properties of Bacillus cereus and Staphylococcus epidermidis

Although the antimicrobial activity of nanoparticles (NPs) penetrating inside the cell is widely recognised, the toxicity of large NPs (>10 nm) that cannot be translocated across bacterial membranes remains unclear. Therefore, this study was performed to elucidate the direct effects of Ag-NPs, Cu-NPs, ZnO-NPs and TiO2-NPs on relative membrane potential, permeability, hydrophobicity, structural changes within chemical compounds at the molecular level and the distribution of NPs on the surfaces of the bacteria Bacillus cereus and Staphylococcus epidermidis. Overall analysis of the results indicated the different impacts of individual NPs on the measured parameters in both strains depending on their type and concentration. B. cereus proved to be more resistant to the action of NPs than S. epidermidis. Generally, Cu-NPs showed the most substantial toxic effect on both strains; however, Ag-NPs exhibited negligible toxicity. All NPs had a strong affinity for cell surfaces and showed strain-dependent characteristic dispersion. ATR-FTIR analysis explained the distinctive interactions of NPs with bacterial functional groups, leading to macromolecular structural modifications. The results presented provide new and solid evidence for the current understanding of the interactions of metallic NPs with bacterial membranes.

Silver Nanoparticles-Chitosan Nanocomposites: A Comparative Study Regarding Different Chemical Syntheses Procedures and Their Antibacterial Effect

Nanocomposites based on silver nanoparticles and chitosan present important advantages for medical applications, showing over time their role in antibacterial evaluation. This work presents the comparative study of two chemical synthesis procedures of nanocomposites, based on trisodium citrate dihydrate and sodium hydroxide, using various chitosan concentrations for a complex investigation. The nanocomposites were characterized by AFM and DLS regarding their dimensions, while FT-IR and UV-VIS spectrometry were used for the optical properties and to reveal the binding of silver nanoparticles with chitosan. Their antibacterial effect was determined using a disk diffusion method on two bacteria strains, E. coli and S. aureus. The results indicate that, when using both methods, the nanocomposites obtained were below 100 nm, yet the antibacterial effect proved to be stronger for the nanocomposites obtained using sodium hydroxide. Furthermore, the antibacterial effect can be related to the nanocomposites' sizes, since the smallest dimension nanocomposites exhibited the best bacterial growth inhibition on both bacteria strains we tested and for both types of silver nanocomposites.

The Effects of Silver Nanoparticles (AgNPs) on Thermophilic Bacteria: Antibacterial, Morphological, Physiological and Biochemical Investigations

Since thermophilic microorganisms are valuable sources of thermostable enzymes, it is essential to recognize the potential toxicity of silver nanoparticles used in diverse industrial sectors. Thermophilic bacteria Geobacillus vulcani 2Cx, Bacillus licheniformis 3CA, Paenibacillus macerans 3CA1, Anoxybacillus ayderensis FMB1, and Bacillus paralicheniformis FMB2-1 were selected, and their MIC and MBC values were assessed by treatment with AgNPs in a range of 62.5-1500 μg mL-1. The growth inhibition curves showed that the G. vulcani 2Cx, and B. paralicheniformis FMB2-1 strains were more sensitive to AgNPs, demonstrating a reduction in population by 71.1% and 31.7% at 62.5 μg mL-1 and by 82.9% and 72.8% at 250 μg mL-1, respectively. TEM and FT-IR analysis revealed that AgNPs caused structural damage, cytoplasmic leakage, and disruption of cellular integrity. Furthermore, cell viability showed a significant decrease alongside an increase in superoxide radical (SOR; O2-) production. β-galactosidase biosynthesis decreased to 28.8% level at 500 μg mL-1 AgNPs for G. vulcani 2Cx, 32.2% at 250 μg mL-1 for A. ayderensis FMB1, and 38.8% only at 62.5 μg mL-1, but it was completely inhibited at 500 μg mL-1 for B. licheniformis 3CA. Moreover, B. paralicheniformis FMB2-1 showed a significant decrease to 11.2% at 125 μg mL-1. This study is the first to reveal the toxic effects of AgNPs on thermophilic bacteria.

The Biosynthesis, Accumulation of Phenolic Compounds and Antioxidant Response in Lactuca sativa L. Plants Inoculated with a Biofertilizer Based on Soil Yeast and Iron Nanoparticles

Lettuce is a vegetable that contributes vitamins, minerals, fibre, phenolic compounds and antioxidants to the human diet. In the search for improving production conditions and crop health, the use of microorganisms with plant growth-promoting capabilities, such as soil yeasts (PGPY), in conjunction with nanotechnology could offer sustainable development of agroecosystems. This study evaluated the synthesis of health-promoting bioactive compounds in lettuce under the application of soil yeast and an iron nanoparticle (NP-Fe2O3) encapsulated in alginate beads. Two yeast strains, Candida guillermondii and Rhodotorula mucilaginosa, and a consortium of both yeasts were used in the presence and absence of Fe2O3-NPs. Phenolic compounds were identified and quantified via HPLC-ESI-Q-ToF and antioxidant activity. Ten phenolic compounds were identified, highlighting the chicoric acid isomer and two quercetin glycosides with high concentrations of up to 100 µg g-1 in treatments with C. guillermondii. Treatments with R. mucilaginosa and NPs-Fe2O3 presented an increase in antioxidant activity, mainly in TEAC, CUPRAC and DPPH activities in leaves, with significant differences between treatments. Therefore, the use of encapsulated soil yeasts is a viable alternative for application in vegetables to improve the biosynthesis and accumulation of phenolic compounds in lettuce and other crops.

From lab to ecosystem: Understanding the ecological footprints of engineered nanoparticles

Nanotechnology has attained significant attention from researchers in past decades due to its numerous advantages, such as biocompatibility, biodegradability, and improved stability over conventional drug delivery systems. The fabrication of engineered nanoparticles (ENPs), including carbon nanotubes (CNTs), fullerenes, metallic and metal oxide-based NPs, has been steadily increasing day due to their wide range of applications from household to industrial applications. Fabricated ENPs can release different materials into the environment during their fabrication process. The effect of such materials on the environment is the primary concern with due diligence on the safety and efficacy of prepared NPs. In addition, an understanding of chemistry, reactivity, fabrication process, and viable mechanism of NPs involved in the interaction with the environment is very important. To date, only a limited number of techniques are available to assess ENPs in the natural environment which makes it difficult to ascertain the impact of ENPs in natural settings. This review extensively examines the environmental effects of ENPs and briefly discusses useful tools for determining NP size, surface charge, surface area, and external appearance. In conclusion, the review highlights the potential risks associated with ENPs and suggests possible solutions.

Bioinspired silver nanoparticle-based nanocomposites for effective control of plant pathogens: A review

Plant pathogens, including bacteria, fungi, and viruses, pose significant challenges to the farming community due to their extensive diversity, the rapidly evolving phenomenon of multi-drug resistance (MDR), and the limited availability of effective control measures. Amid mounting global pressure, particularly from the World Health Organization, to limit the use of antibiotics in agriculture and livestock management, there is increasing consideration of engineered nanomaterials (ENMs) as promising alternatives for antimicrobial applications. Studies focusing on the application of ENMs in the fight against MDR pathogens are receiving increasing attention, driven by significant losses in agriculture and critical knowledge gaps in this crucial field. In this review, we explore the potential contributions of silver nanoparticles (AgNPs) and their nanocomposites in combating plant diseases, within the emerging interdisciplinary arena of nano-phytopathology. AgNPs and their nanocomposites are increasingly acknowledged as promising countermeasures against plant pathogens, owing to their unique physicochemical characteristics and inherent antimicrobial properties. This review explores recent advancements in engineered nanocomposites, highlights their diverse mechanisms for pathogen control, and draws attention to their potential in antibacterial, antifungal, and antiviral applications. In the discussion, we briefly address three crucial dimensions of combating plant pathogens: green synthesis approaches, toxicity-environmental concerns, and factors influencing antimicrobial efficacy. Finally, we outline recent advancements, existing challenges, and prospects in scholarly research to facilitate the integration of nanotechnology across interdisciplinary fields for more effective treatment and prevention of plant diseases.

New insights into the environmental application of hybrid nanoparticles in metal contaminated agroecosystem: A review

Heavy metals (HMs) contamination in agricultural soils is a major constraint to provide safe food to society. Cultivation of food crops on these soils, channels the HMs into the food chain and causes serious human health and socioeconomic problems. Multiple conventional and non-conventional remedial options are already in practice with variable success rates, but nanotechnology has proved its success due to higher efficiency. It also led the hypothesis to use hybrid nanoparticles (HNPs) with extended benefits to remediate the HMs and supplement nutrients to enhance the crop yield in the contaminated environments. Hybrid nanoparticles are defined as exclusive chemical conjugates of inorganic and/or organic nanomaterials that are combinations of two or more organic components, two or more inorganic components, or at least one of both types of components. HNPs of different elements like essential nutrients, beneficial nutrients and carbon-based nanoparticles are used for the remediation of metals contaminated soil and the production of metal free crops. Characterizing features of HNPs including particle size, surface area, reactivity, and solubility affect the efficacy of these HNPs in the contaminated environment. Hybrid nanoparticles have great potential to remove the HMs ions from soil solution and restrict their ingress into the root tissues. Furthermore, HNPs of essential nutrients not only compete with heavy metal uptake by plants but also fulfill the need of nutrients. This review provides a comprehensive overview of the challenges associated with application of HNPs in contaminated soils, environmental implications, their remediation ability, and factors affecting their dynamics in environmental matrices.

Microbial bioprocess performance in nanoparticle-mediated composting

Microbial composting is one of the most cost-effective techniques for degradation, remediation, nutrition, etc. Currently, there is faster growth and development in nanotechnology in different sectors. This development leads nanoparticles (NPs) to enter into the composts in different ways. First, unintentional entry of NPs into the composts via: waste discharge, buried solid waste, surface runoff, direct disposal into wastes (consumer goods, food, pharmaceuticals, and personal care products). Second, intentional mediation of the NPs in the composting process is a novel approach developed to enhance the degradation rate of wastes and as a nutrient for plants. The presence of NPs in the composts can cause nanotoxicity. Conversely, their presence might also be beneficial, such as soil reclamations, degradation, etc. Alternatively, metal NPs are also helpful for all living organisms, including microorganisms, in various biological processes, such as DNA replication, precursor biosynthesis, respiration, oxidative stress responses, and transcription. NPs show exemplary performance in multiple fields, whereas their role in composting process is worth studying. Consequently, this article aids the understanding of the role of NPs in the composting process and how far their presence can be beneficial. This article reviews the significance of NPs in: the composting process, microbial bioprocess performance during nano composting, basic life cycle assessment (LCA) of NP-mediated composting, and mode of action of the NPs in the soil matrix. This article also sheds insight on the notion of nanozymes and highlights their biocatalytic characterization, which will be helpful in future composting research.

Changes of microbiome in response to supplements with silver nanoparticles in cotton rhizosphere

The current study focuses on analyzing the effects of supplements containing silver nanoparticles (AgNPs) on plant growth and rhizospheric bacterial communities. Specifically, the impact of AgNP supplements was assessed on both plant growth promoting traits and bacterial communities in the soil. To do this, a screening process was conducted to select bacteria capable of synthesizing AgNPs through extracellular biosynthesis. UV-Visible spectrophotometer, Fourier transform infrared, X-ray diffraction, scanning electron microscope, and field emission scanning electron microscopy all confirmed, produced AgNPs is in agglomerates form. The resulting AgNPs were introduced into soil along with various supplements and their effects were evaluated after 10 days using next generation sequencing (Illumina-16S rDNA V3-V4 region dependent) to analyze changes in bacterial communities. Seed germination, root-shoot biomass and chlorophyll content were used to assess the growth of the cotton plant, whereas the bacterial ability to promote growth was evaluated by measuring its culturable diversity including traits like phosphate solubilization and indole acetic acid production. The variance in Bray-Curtis β diversity among six selected combinations including control depends largely on the type of added supplements contributing to 95%-97% of it. Moreover, seed germination improves greatly between 63% and 100% at a concentration range of 1.4 to 2.8 mg/L with different types of supplements. Based on the results obtained through this study, it is evident that using AgNPs along with fructose could be an effective tool for promoting Gossypium hirsutum growth and enhancing plant growth traits like profiling rhizospheric bacteria. The results that have been obtained endorse the idea of boosting the growth of rhizospheric bacteria in a natural way when AgNPs are present. Using these supplements in fields that have been contaminated will lead to a better understanding of how ecological succession occurs among rhizospheric bacteria, and what effect it has on the growth of plants.

Plant growth-promoting rhizobacteria: a potential bio-asset for restoration of degraded soil and crop productivity with sustainable emerging techniques

The rapid expansion of degraded soil puts pressure on agricultural crop yield while also increasing the likelihood of food scarcity in the near future at the global level. The degraded soil does not suit plants growth owing to the alteration in biogeochemical cycles of nutrients, soil microbial diversity, soil organic matter, and increasing concentration of heavy metals and organic chemicals. Therefore, it is imperative that a solution should be found for such emerging issues in order to establish a sustainable future. In this context, the importance of plant growth-promoting rhizobacteria (PGPR) for their ability to reduce plant stress has been recognized. A direct and indirect mechanism in plant growth promotion is facilitated by PGPR via phytostimulation, biofertilizers, and biocontrol activities. However, plant stress mediated by deteriorated soil at the field level is not entirely addressed by the implementation of PGPR at the field level. Thus, emerging methods such as CRISPR and nanotechnological approaches along with PGPR could manage degraded soil effectively. In the pursuit of the critical gaps in this respect, the present review discusses the recent advancement in PGPR action when used along with nanomaterials and CRISPR, impacting plant growth under degraded soil, thereby opening a new horizon for researchers in this field to mitigate the challenges of degraded soil.

Environmental effects and interaction of nanoparticles on beneficial soil and aquatic microorganisms

A steadily increasing production volume of nanoparticles reflects their numerous industrial and domestic applications. These economic successes come with the potential adverse effects on natural systems that are associated with their presence in the environment. Biological activities and effects of nanoparticles are affected by their entry method together with their specificities like their size, shape, charge, area, and chemical composition. Particles can be classified as safe or dangerous depending on their specific properties. As both aquatic and terrestrial systems suffer from organic and inorganic contamination, nanoparticles remain a sink for these contaminants. Researching the sources, synthesis, fate, and toxicity of nanoparticles has advanced significantly during the last ten years. We summarise nanoparticle pathways throughout the ecosystem and their interactions with beneficial microorganisms in this research. The prevalence of nanoparticles in the ecosystem causes beneficial microorganisms to become hazardous to their cells, which prevents the synthesis of bioactive molecules from undergoing molecular modifications and diminishes the microbe population. Recently, observed concentrations in the field could support predictions of ambient concentrations based on modeling methodologies. The aim is to illustrate the beneficial and negative effects that nanoparticles have on aqueous and terrestrial ecosystems, as well as the methods utilized to reduce their toxicity.

Biogenic zinc oxide nanoparticles: A viable agricultural tool to control plant pathogenic fungi and its potential effects on soil and plants

Fungal and bacterial pathogens represent some of the greatest challenges facing crop production globally and account for about 20-40 % crop losses annually. This review highlights the use of ZnO NPs as antimicrobial agents and explores their mechanisms of actions against disease causing plant fungal pathogens. The behavior of ZnO NPs in soil and their interactions with the soil components were also highlighted. The review discusses the potential effects of ZnO NPs on plants and their mechanisms of action on plants and how these mechanisms are related to their physicochemical properties. In addition, the reduction of ZnO NPs toxicity through surface modification and coating with silica is also addressed. Soil properties play a significant role in the dispersal, aggregation, stability, bioavailability, and transport of ZnO NPs and their release into the soil. The transport of ZnO NPs into the soil might influence soil components and, as a result, plant physiology. The harmful effects of ZnO NPs on plants and fungi are caused by a variety of processes, the most important of which is the formation of reactive oxygen species, lysosomal instability, DNA damage, and the reduction of oxidative stress by direct penetration/liberation of Zn2+ ions in plant/fungal cells. Based on these highlighted areas, this review concludes that ZnO NPs exhibit its antifungal activity via generations of reactive oxygen species, coupled with the inhibition of various metabolic pathways. Despite the numerous advantages of ZnO NPs, there is need to regulate its uses to minimize the harmful effects that may arise from its applications in the soil and plants.

Unlocking the Potential of Nano-Enabled Precision Agriculture for Efficient and Sustainable Farming

Nanotechnology has attracted remarkable attention due to its unique features and potential uses in multiple domains. Nanotechnology is a novel strategy to boost production from agriculture along with superior efficiency, ecological security, biological safety, and monetary security. Modern farming processes increasingly rely on environmentally sustainable techniques, providing substitutes for conventional fertilizers and pesticides. The drawbacks inherent in traditional agriculture can be addressed with the implementation of nanotechnology. Nanotechnology can uplift the global economy, so it becomes essential to explore the application of nanoparticles in agriculture. In-depth descriptions of the microbial synthesis of nanoparticles, the site and mode of action of nanoparticles in living cells and plants, the synthesis of nano-fertilizers and their effects on nutrient enhancement, the alleviation of abiotic stresses and plant diseases, and the interplay of nanoparticles with the metabolic processes of both plants and microbes are featured in this review. The antimicrobial activity, ROS-induced toxicity to cells, genetic damage, and growth promotion of plants are among the most often described mechanisms of operation of nanoparticles. The size, shape, and dosage of nanoparticles determine their ability to respond. Nevertheless, the mode of action of nano-enabled agri-chemicals has not been fully elucidated. The information provided in our review paper serves as an essential viewpoint when assessing the constraints and potential applications of employing nanomaterials in place of traditional fertilizers.

Physiological and Germination Responses of Muskmelon (Cucumis melo L.) Seeds to Varying Osmotic Potentials and Cardinal Temperatures via a Hydrothermal Time Model

Climatic changes have a direct negative impact on the growth, development, and productivity of crops. The water potential (ψ) and temperature (T) are important limiting factors that influence the rate of seed germination and growth indices. To examine how the germination of seed responds to changes in water potential and temperature, the hydrotime model and hydrothermal model (HTT) have been employed. The HTT calculates the concept of germination time across temperatures, between Tb-To, with alteration, and between Tb-Tc, in supra-optimal ranges. The seeds of Cucumis melo L. were germinated in the laboratory for a hydro-thermal time experiment. Seeds were sown in Petri dishes containing a double-layered filter paper at different osmotic potentials (0, -0.2, -0.4, -0.6, and -0.8 MPa) by providing PEG 6000 (drought stress enhancer) at different temperatures (15, 20, 25, 30, and 35 °C). The controlled replicate was treated with 10 mL of distilled water and the rest with 10 mL of PEG solution. Results indicated that the seed vigor index (SVI-II) was highest at 15 °C with 0 MPa and lowest at 30 °C with -0.2 MPa. However, the highest activity was shown at 15 °C by catalase (CAT) and guaiacol peroxidase (GPX) at (-0.6 MPa), while the lowest values of CAT and GPX were recorded for control at 35 °C with -0.8 MPa at 35 °C, respectively. Germination energy was positively correlated with germination index (GI), germination percentage (G%), germination rate index, seed vigor index-I (SVI-I), mean moisture content (MMC), and root shoot ratio (RSR) and had a negative correlation with mean germination rate, percent moisture content of shoot and root, CAT, superoxide dismutase, peroxidase ascorbate peroxidase, and GPX. In conclusion, thermal and hydrotime models correctly predicted muskmelon germination time in response to varying water potential and temperature. The agronomic attributes were found to be maximum at 30 °C and minimum at 15 °C.

Nanopesticide risk assessment based on microbiome profiling - Community structure and functional potential as biomarkers in captan@ZnO35-45 nm and captan@SiO220-30 nm treated orchard soil

Nanoformulation should minimise the usage of pesticides and limit their environmental footprint. The risk assessment of two nanopesticides with fungicide captan as an active organic substance and ZnO35-45 nm or SiO220-30 nm as nanocarriers was evaluated using the non-target soil microorganisms as biomarkers. The first time for that kind of nanopesticides next-generation sequencing (NGS) of bacterial 16 S rRNA and fungal ITS region and metagenomics functional predictions (PICRUST2) was made to study structural and functional biodiversity. During a 100-day microcosm study in soil with pesticide application history, the effect of nanopesticides was compared to pure captan and both nanocarriers. Nanoagrochemicals affected microbial composition, especially Acidobacteria-6 class, and alpha diversity, but the observed effect was generally more substantial for pure captan. As for beta diversity, the negative impact was detected only in response to captan and still observed on day 100. Fungal community in the orchard soil showed only a decrease in phylogenetic diversity in captan set-up since day 30. PICRUST2 analysis confirmed several times lower impact of nanopesticides considering the abundance of functional pathways and genes encoding enzymes. Furthermore, the overall data indicated that using SiO220-30 nm as a nanocarrier speeds up a recovery process compared to ZnO35-45 nm.

Influence of tomato waste composts on dry matter and heavy metals content in cucumber and summer squash seedlings

Huge quantities of agricultural waste are available annually in Saudi Arabia, which are not well exploited, leading to large environmental pollution and health problems. The use of different proportions of tomato waste compost (TWC) mixed with commercial peat-moss as a natural, economical, cheap and environmentally friendly fertilizer for fertilizing vegetables is very important, therefore, this study is concerned with investigating and evaluating the dry matter content (DM) and the accumulated heavy metal contents (HMs) in the root and leaf seedlings tissues of cucumber and summer squash plants as a result of using this fertilizer. Five ratios of mixtures (vermiculite: peat moss: TWC by weight) used in the experiment, and the TWC in the mixture represents 0, 5, 10, 15 and 20% (by wieght). The results indicated that, the DM contents in the root and leaf tissues were relatively close between cucumber and summer squash seedlings. However, they were higher in the root than in leaf tissues, particularly under 20% TWC. A TWC application ratio of 20% reduced concentrations of the most HMs in the two vegetable species seedlings due to high EC and pH levels. The amounts of HMs in vegetable species were not high, which proves the that transfer of HMs from the TWC substrate to the seedlings is determined chiefly by metal bioavailability and by a vegetable species. DM, mineral and nutritional quality of vegetable seedlings showed that substrates containing 5% and 10% TWC appeared to be the most suitable growing medium for economic vegetable seedlings; and it is recommended for use in the nursery production. Implications: The idea of this research revolves around the use of different proportions of tomato waste compost in fertilizing cucumber and summer squash seedlings and investigate the effect of this compost on dry matter (DM) and heavy metal (HMs) contents in the root and leaf tissues of the seedlings, and fruit quality of cucumber and summer squash plants.

Recent trends and perspectives in the application of metal and metal oxide nanomaterials for sustainable agriculture

Sustainable ecosystem management leads to the use of eco-friendly agricultural techniques for crop production. One of them is the use of metal and metal oxide nanomaterials and nanoparticles, which have proven to be a valuable option for the improvement of agricultural food systems. Moreover, the biological synthesis of these nanoparticles, from plants, bacteria, and fungi, also contributes to their eco-friendly and sustainable characteristics. Nanoparticles, which vary in size from 1 to 100 nm have a variety of mechanisms that are safer and more efficient than conventional fertilizers. Their usage as fertilizers and insecticides in agriculture is gaining favor in the scientific community to maximize crop output. More studies in this field will increase our understanding of this new technology and its broad acceptance in terms of performance, affordability, and environmental protection, as certain nanoparticles may outperform conventional fertilizers and insecticides. Accordingly, to the information gathered in this review, nanoparticles show remarkable potential for enhancing crop production, improving soil quality, and protecting the environment, however, metal and metal oxide NPs are not widely employed in agriculture. Many features of nanoparticles are yet left over, and it is necessary to uncover them. In this sense, this review article provides an overview of various types of metal and metal oxide nanoparticles used in agriculture, their characterization and synthesis, the recent research on them, and their possible application for the improvement of crop productivity in a sustainable manner.

Pouteria caimito fruit derived nanoparticles inhibited the apple ring rot disease as well as extended the shelf-life of sliced apples

Background

Apple disease, exaggerated by Botryosphaeria dothidea, is a foremost intimidating problem for extending the apple fruit shelf-life and producing substantial economic losses for cultivators and distributors. Alternate sources are urgently needed to prevent or inhibit the ring rot infection of apple fruit instigated by Botryosphaeria dothidea.

Objective

In this current study, we premeditated to make novel organic nanoparticles as of Pouteria caimito fruit extract and calcium chloride (PCNP), which were used to evaluate the preventive outcome of Botryosphaeria dothidea-caused apple disease on postharvest apple fruits.

Results

Our findings corroborated that the fruit derived nanoparticle had been confirmed for quality and size by altered estimations such as fourier transform infrared (FTIR), UV-vis spectroscopic analysis, scanning electron microscope and energy dispersive X-ray (SEM and EDX) estimation, and dynamic light scattering (DLS) analysis. In addition, we have investigated the excellent inhibitory action of the pathogen infection in apples initiated by Botryosphaeria dothidea. The protective enzymes function was pointedly improved in nanoparticle-treated apple fruits once equated with those of control apple fruits. The catalase (CAT) and superoxide dismutase (SOD) activities were pointedly improved in nanoparticle-treated fruits when compared to those of control fruits. The shelf-life extension studies were conducted for 7 days with a fresh-cut apple. The total soluble solid, pH, weight loss, and sensory studies were analyzed, and they proved the extension of sliced apple shelf life up to 7 days.

Conclusions

The discoveries of this study provided a well-organized, harmless, and environment-friendly substitute to control the apple disease as well as the durability postponement of sliced apples 7 days or may longer.

Noteworthy biocompatibility of effective microorganisms (EM) like microbial beneficial culture formulation with metal and metal oxide nanoparticles

The present study evaluates the biocompatibility of silver and zinc oxide nanoparticles with various effective microorganisms (EM), like beneficial microbial formulations. The respective nanoparticle was synthesised by chemical reduction of metal precursor with reducer via simple route green technology principles. The synthesised nanoparticles were characterised by UV visible spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) studies, revealing highly stable, nanoscale particles with marked crystallinity. EM-like beneficial cultures composed of viable cells of Lactobacillus lactis, Streptomyces sp, Candida lipolytica, and Aspergillus oryzae were formulated with rice bran, sugarcane syrup, and groundnut cake. The respective formulation was inoculated into the nanoparticles amalgamated pots raised with green gram seedlings. Biocompatibility was determined by measuring plant growth parameters of a green gram at pre-determined periods associated with enzymatic antioxidants like catalase (CAT), superoxide dismutase (SOD), and glutathione S transferase (GST) levels. Most significantly, the expression level of these enzymatic antioxidants level was also investigated by quantitative real-time polymerase chain reaction (qRT-PCR). The impact of the soil conditioning effect on soil nutrients like nitrogen, phosphorous, potassium, organic carbon, soil enzymes glucosidases, and β-xylosidases activity was also studied. Among the formulation, rice bran-groundnut cake-sugar syrup formulation recorded the best biocompatibility. This formulation showed high growth promotion, soil conditioning effect and no impact on the oxidative stress enzymes genes that revealed the best compatibility of nanoparticles. This study concluded that biocompatible, eco-friendly formulations of microbial inoculants could be used for the desirable agro active properties that show extreme tolerance or biocompatibility to the nanoparticles. This present study also suggests the utilisation of the above said beneficial microbial formulation and metal-based nanoparticles with desirable agro active properties in a synergistic manner due to their high tolerance or compatibility towards the metal or metal oxide nanoparticles.

Effects of Poultry Manure on the Growth, Physiology, Yield, and Yield-Related Traits of Maize Varieties

Industries play a significant role in the improvement of lifestyle and in the development of a country. However, the byproducts from these industries are a source of environmental pollution. The proper use of the byproducts of these industries can help to cope with environmental pollution. Some byproducts have high nutritional content and are good for crop plants. The purpose of this research was to investigate the effect of different rates of poultry manure on the soil chemical properties, growth, and yield of maize. A pot experiment was conducted in the botanical garden of the Department of Botany, University of Sargodha, Pakistan to investigate the effect of various treatments of poultry manure (0, 25, 50, 75, and 100 g/pot) on the morphological, physiological, and yield attributes of two maize varieties, Pearl and MMRI. Treatment T₁ was a mixture of soil and 75 g/pot poultry manure, T₂ was a mixture of soil and 50 g/pot poultry manure, T₃ was a mixture of soil and 25 g/pot poultry manure, and T₄ was 100 g/pot poultry manure. Soil without any industrial byproduct (100% soil only) was used as the control (T₀). The results revealed that the use of poultry manure enhanced the physical properties of the soil. Available P and soil organic matter were improved in soil amended with poultry manure. It is evident from the results that the vegetative growth of both maize varieties was significantly enhanced by growing in soil amended with poultry manure as compared to their respective control. Similar responses were also recorded for the physiological attributes of leaf area, photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency of both varieties. Yield and yield-contributing traits of both maize varieties were significantly improved by growing plants in soil amended with 50 and 75 g/pot of poultry manure. It is also inferred that the use of 50 g/pot poultry manure in soil amendment is an eco-friendly and economically effective option for maize growers of arid and semiarid regions to enhance the kernel yield and profit per annum. Poultry manure could be useful to ameliorate the adverse effects of salinity stress on all parameters, particularly the grain yield. Furthermore, this would be a useful and economical method for the safe disposal of byproducts.

Ameliorative Effects of Exogenous Potassium Nitrate on Antioxidant Defense System and Mineral Nutrient Uptake in Radish (Raphanus sativus L.) under Salinity Stress

Soil salinization has become a major issue around the world in recent years, as it is one of the consequences of climate change as sea levels rise. It is crucial to lessen the severe consequences of soil salinization on plants. A pot experiment was conducted to regulate the physiological and biochemical mechanisms in order to evaluate the ameliorative effects of potassium nitrate (KNO₃) on Raphanus sativus L. genotypes under salt stress. The results from the present study illustrated that the salinity stress induced a significant decrease in shoot length, root length, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, number of leaves per plant, leaf area chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid, net photosynthesis, stomatal conductance, and transpiration rate by 43, 67, 41, 21, 34, 28, 74, 91, 50, 41, 24, 34, 14, 26, and 67%, respectively, in a 40 day radish while decreased by 34, 61, 49, 19, 31, 27, 70, 81, 41, 16, 31, 11, 21, and 62%, respectively, in Mino radish. Furthermore, MDA, H₂O₂ initiation, and EL (%) of two varieties (40 day radish and Mino radish) of R. sativus increased significantly (P < 0.05) by 86, 26, and 72%, respectively, in the roots and also increased by 76, 106, and 38% in the leaves in a 40 day radish, compared to the untreated plants. The results also elucidated that the contents of phenolic, flavonoids, ascorbic acid, and anthocyanin in the two varieties (40 day radish and Mino radish) of R. sativus increased with the exogenous application of KNO₃ by 41, 43, 24, and 37%, respectively, in the 40 day radish grown under the controlled treatments. Results indicated that implementing KNO₃ exogenously in the soil increased the activities of antioxidants like SOD, CAT, POD, and APX by 64, 24, 36, and 84% in the roots and also increased by 21, 12, 23, and 60% in the leaves of 40 day radish while also increased by 42, 13, 18, and 60% in the roots and also increased by 13, 14, 16, and 41% in the leaves in Mino radish, respectively, in comparison to those plants grown without KNO₃. We found that KNO₃ substantially improved plant growth by lowering the levels of oxidative stress biomarkers, thereby further stimulating the antioxidant potential system, which led to an improved nutritional profile of both R. sativus L. genotypes under normal and stressed conditions. The current study would offer a deep theoretical foundation for clarifying the physiological and biochemical mechanisms by which the KNO₃ improves salt tolerance in R. sativus L. genotypes.

Microbe-Plant Interactions Targeting Metal Stress: New Dimensions for Bioremediation Applications

In the age of industrialization, numerous non-biodegradable pollutants like plastics, HMs, polychlorinated biphenyls, and various agrochemicals are a serious concern. These harmful toxic compounds pose a serious threat to food security because they enter the food chain through agricultural land and water. Physical and chemical techniques are used to remove HMs from contaminated soil. Microbial-metal interaction, a novel but underutilized strategy, might be used to lessen the stress caused by metals on plants. For reclaiming areas with high levels of heavy metal contamination, bioremediation is effective and environmentally friendly. In this study, the mechanism of action of endophytic bacteria that promote plant growth and survival in polluted soils-known as heavy metal-tolerant plant growth-promoting (HMT-PGP) microorganisms-and their function in the control of plant metal stress are examined. Numerous bacterial species, such as Arthrobacter, Bacillus, Burkholderia, Pseudomonas, and Stenotrophomonas, as well as a few fungi, such as Mucor, Talaromyces, Trichoderma, and Archaea, such as Natrialba and Haloferax, have also been identified as potent bioresources for biological clean-up. In this study, we additionally emphasize the role of plant growth-promoting bacteria (PGPB) in supporting the economical and environmentally friendly bioremediation of heavy hazardous metals. This study also emphasizes future potential and constraints, integrated metabolomics approaches, and the use of nanoparticles in microbial bioremediation for HMs.

Converting Nanotoxicity Data to Information Using Artificial Intelligence and Simulation

Decades of nanotoxicology research have generated extensive and diverse data sets. However, data is not equal to information. The question is how to extract critical information buried in vast data streams. Here we show that artificial intelligence (AI) and molecular simulation play key roles in transforming nanotoxicity data into critical information, i.e., constructing the quantitative nanostructure (physicochemical properties)-toxicity relationships, and elucidating the toxicity-related molecular mechanisms. For AI and molecular simulation to realize their full impacts in this mission, several obstacles must be overcome. These include the paucity of high-quality nanomaterials (NMs) and standardized nanotoxicity data, the lack of model-friendly databases, the scarcity of specific and universal nanodescriptors, and the inability to simulate NMs at realistic spatial and temporal scales. This review provides a comprehensive and representative, but not exhaustive, summary of the current capability gaps and tools required to fill these formidable gaps. Specifically, we discuss the applications of AI and molecular simulation, which can address the large-scale data challenge for nanotoxicology research. The need for model-friendly nanotoxicity databases, powerful nanodescriptors, new modeling approaches, molecular mechanism analysis, and design of the next-generation NMs are also critically discussed. Finally, we provide a perspective on future trends and challenges.

Combating Microbial Infections Using Metal-Based Nanoparticles as Potential Therapeutic Alternatives

The nature of microorganisms and the efficiency of antimicrobials have witnessed a huge co-dependent change in their dynamics over the last few decades. On the other side, metals and metallic compounds have gained popularity owing to their effectiveness against various microbial strains. A structured search of both research and review papers was conducted via different electronic databases, such as PubMed, Bentham, Springer, and Science Direct, among others, for the present review. Along with these, marketed products, patents, and Clinicaltrials.gov were also referred to for our review. Different microbes such as bacteria, fungi, etc., and their diverse species and strains have been reviewed and found to be sensitive to metal-carrying formulations. The products are observed to restrict growth, multiplication, and biofilm formation effectively and adequately. Silver has an apt use in this area of treatment and recovery, and other metals like copper, gold, iron, and gallium have also been observed to generate antimicrobial activity. The present review identified membrane disruption, oxidative stress, and interaction with proteins and enzymes to be the primary microbicidal processes. Elaborating the action, nanoparticles and nanosystems are shown to work in our favor in well excelled and rational ways.

Cerium oxide nanoparticles (nCeO2) exert minimal adverse effects on microbial communities in soils with and without biosolids amendment

Increased use of nano-cerium oxide (nCeO₂) in an array of industrial applications has raised environmental concerns due to potential increased loadings to the soil environment. This research investigated the potential adverse effects of nCeO₂ (10-30 nm) on the soil microbial community in two exposure scenarios: direct application to soil, and indirect application to soil through chemical spiking of biosolids, followed by mixing into soil. Total Ce in test soils without, and with biosolids amendment, ranged from 44 to 770, and 73 to 664 mg Ce kg^-1 soil, respectively. In order to help distinguish whether observed effects were elicited by the solid-phase colloids or the activity of dissolved Ce, a soluble Ce salt (Ce (NO₃)₃) treatment was included in select assays. A suite of tests was used to investigate effects on critical processes: microbial growth (heterotrophic plate count), microbial activity (organic matter (OM) decomposition, enzyme activity and, nitrification) and diversity (structural and functional). Although results showed significant inhibition on microbial growth in soil without biosolids amendment at ≥ 156 mg Ce kg^-1 soil by week 5, these results were inconsistent and non-significant thereafter. In general, nCeO₂ showed no evidence of consistent adverse effects on OM decomposition, nitrification, soil enzyme activities and functional diversity. Leucine aminopeptidase showed significant (p< 0.05) stimulatory effects over time at ≥ 44 mg Ce kg^-1 in soils without biosolids, which was not observed in soils with biosolids amendment. The lack of inhibitory effects of nCeO₂ may be attributed to its low solubility; Ce in soil extracts (0.01 M CaCl₂) were all below detection (< 0.003 mg kg^-1) in the nCeO₂-spiked soils, but detectable in the Ce (NO₃)₃ samples. In contrast, soluble Ce at 359 mg Ce kg^-1 showed a significant reduction in OM decomposition and effects on microbial genomic diversity based on the 16S rDNA data in soils with and without biosolids amendment (359 and 690 mg Ce kg^-1). The nCeO₂ behaviour and effects information described herein are expected to help fulfill data gaps for the characterization of this priority nanomaterial.

One-pot synthesis of metal oxide-clay composite for the evaluation of dye removal studies: Taguchi optimization of parameters and environmental toxicity studies

The present study demonstrates the synthesis of eco-friendly metal oxide-clay composites (MgO-clay and CaO-clay) with phytochemical functionalization. The physical and chemical properties of prepared composites were characterized using standard techniques viz. scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The effect of pH on the dye adsorption capability of the synthesized composites was studied. The adsorption of an anionic dye methyl orange (MO) and a cationic due methylene blue (MB) was favored in the acidic and basic regions, respectively. The Taguchi design approach was adopted for the removal of MO and MB from wastewater using the synthesized composites. The obtained results suggest that initial dye concentration and composite dosage were the most influential parameters in dye removal among all the studied parameters. The adsorption experiments were carried out using MgO-clay and CaO-clay composites with the optimum conditions obtained from Taguchi optimization to validate the predicted response. The experimental parameters viz. the effect of contact time, initial dye concentration, and solution temperature were studied for screened composite (CaO-clay) with optimized conditions. The obtained results were interpreted using standard isotherms and kinetic models. A maximum adsorption capacity of 571 ± 10 and 859 ± 14 mg g^-1 was obtained from the Langmuir adsorption isotherm for MO and MB, respectively. Regeneration studies suggested that the CaO-clay composite can be utilized up to 3 cycles with reduced adsorption capacity of the dyes over cycles due to the solid binding nature of dyes on the CaO-clay composite. The fresh and utilized CaO-clay composite were tested for their environmental toxicity analysis using ecologically important soil microorganisms. The obtained results suggested no detrimental effects on soil microbe's functionality, indicating their threat-free disposal in the soil environment.

The significance of metallic nanoparticles in the emerging, development and spread of antibiotic resistance

An ever-increasing number of newly synthesised nanoparticles have a constantly expanding range of applications. The large-scale implementation of nanoparticles will inevitably lead to intentional or accidental contamination of various environments. Since the major benefit of using several metallic nanoparticles is antimicrobial activity, these emerging contaminants may have a potentially hazardous impact on the development and spread of antibiotic resistance - a challenge that threats infection therapy worldwide. Few studies underline that metallic nanoparticles may affect the emergence and evolution of resistance via mutations and horizontal transfer between different bacterial species. Due to the complexity of factors and mechanisms involved in disseminating antibiotic resistance, it is crucial to investigate if metallic nanoparticles play a significant role in this process through co-selection ability and pressure exerted on bacteria. The aim of this review is to summarise the current research on mutations and three main horizontal gene transfer modes facilitated by nanoparticles. Here, the current results in the field are presented, major knowledge gaps and the necessity for more environmentally relevant studies are discussed.

Copper-oxide nanoparticles exert persistent changes in the structural and functional microbial diversity: A 60-day mesocosm study of zinc-oxide and copper-oxide nanoparticles in the soil-microorganism-nanoparticle system

Recent advances in nanotechnology and development of nanoformulation methods, has enabled the emergence of precision farming - a novel farming method that involves nanopesticides and nanoferilizers. Zinc-oxide nanoparticles serve as a Zn source for plants, but they are also used as nanocarriers for other agents, whereas copper-oxide nanoparticles possess antifungal activity, but in some cases may also serve as a micronutrient providing Cu ions. Excessive application of metal-containing agents leads to their accumulation in soil, where they pose a threat to non-target soil organisms. In this study, soils obtained from the environment were amended with commercial zinc-oxide nanoparticles: Zn-O_xNPs_(10-30), and newly-synthesized copper-oxide nanoparticles: Cu-O_xNPs_(1-10). Nanoparticles (NPs) in 100 and 1000 mg kg^-1 concentrations were added in separate set-ups, representing a soil-microorganism-nanoparticle system in a 60-day laboratory mesocosm experiment. To track environmental footprint of NPs on soil microorganisms, a Phospholipd Fatty Acid biomarker analysis was employed to study microbial community structure, whereas Community-Level Physiological Profiles of bacterial and fungal fractions were measured with Biolog Eco and FF microplates, respectively. The results revealed a prominent and persistent effects exerted by copper-containing nanoparticles on non-target microbial communities. A severe loss of Gram-positive bacteria was observed in conjunction with disturbances in bacterial and fungal CLPPs. These effects persisted till the end of a 60-day experiment, demonstrating detrimental rearrangements in microbial community structure and functions. The effects imposed by zinc-oxide NPs were less pronounced. As persistent changes were observed for newly synthesized Cu-containing NPs, this work stresses the need for obligatory testing of nanoparticle interactions with non-target microbial communities in long-term experiments, especially during the approval procedures of novel nano-substances. It also underlines the role of in-depth physical and chemical studies of NP-containing agents, which may be tweaked to mitigate the unwanted behavior of such substances in the environment and preselect their beneficial characteristics.

An overview of topical lipid-based and polymer-based nanocarriers for treatment of psoriasis

Psoriasis is a consistently recurring, inflammatory skin disease, affecting about 2 - 5 % of the world population. Different types of psoriasis can be observed such as guttate psoriasis, pustular psoriasis, psoriatic arthritis, scalp psoriasis, flexural psoriasis etc. Several therapeutic approaches are available for the treatment of psoriasis. However, none of them are entirely safe and effective to treat the disease without compromising patient compliance. The traditional treatment plan is associated with harmful side effects such asimmune system suppression and damage of essential organs at high doses, which poses a challenge to treat psoriasis. Novel drug delivery systems are being developed to replace traditional therapy in order to address these shortcomings. Currently, nanoformulations have gained widespread application for treatment of psoriasis. Researchers have developed different types of lipid-based nanoparticles like liposomes, niosomes, ethosomes, transethosomes, nanostructured lipid carriers and solid lipid nanoparticles. These innovative formulations provide advantages in terms of reduction in dose, dosing frequency, dose-dependency with enhanced efficacy, improved encapsulation efficiency, controlled release, increased surface area, high bioavailability and greater stratum corneum permeability. This review highlights detailed and comparative discussion of lipid-based and polymer-based nanoparticles for psoriasis along with the pathophysiology and other treatments of psoriasis.

Undesirable consequences of the metallic nanoparticles action on the properties and functioning of Escherichia coli, Bacillus cereus and Staphylococcus epidermidis membranes

Controversial and inconsistent findings on the toxicity of metallic nanoparticles (NPs) against many bacteria are common in recorded studies; therefore, further advanced experimental work is needed to elucidate the mechanisms underlying nanotoxicity. This study deciphered the direct effects of Ag-NPs, Cu-NPs, ZnO-NPs and TiO₂-NPs on membrane permeability, cytoplasmic leakage, ATP level, ATPase activity and fatty acid profiling of Escherichia coli, Bacillus cereus and Staphylococcus epidermidis as model microorganisms. A multifaceted analysis of all collected results indicated the different influences of individual NPs on the measured parameters depending on their type and concentration. Predominantly, membrane permeability was correlated with increased cytoplasmic leakage, reduced total ATP levels and ATPase activity. The established fatty acid profiles were unique and concerned various changes in the percentages of hydroxyl, cyclopropane, branched and unsaturated fatty acids. Decisively, E. coli was more susceptible to changes in measured parameters than B. cereus and S. epidermidis. Also, it was established that ZnO-NPs and Cu-NPs had a major differentiating impact on studied parameters. Additionally, bacterial cell imaging using scanning electron microscopy elucidated different NPs distributions on the cell surface. The presented results are believed to provide novel, valuable and accumulated knowledge in the understanding of NPs action on bacterial membranes.

Apoptotic, cytotoxic, antioxidant, and antibacterial activities of biosynthesized silver nanoparticles from nettle leaf

Here, we reported the biosynthesis of silver nanoparticles (AgNPs) using Urtica dioica (nettle) leaf extract as green reducing and capping agents and investigate their anticancer and antibacterial, activity. The Nettle-mediated biosynthesized AgNPs was characterized by UV-Vis a spectrophotometer. Their size, shape and elemental analysis were determined with the using of SEM and TEM. The crystal structure was determined by XRD and the biomolecules responsible for the reduction of Ag⁺ were determined using FTIR analysis. Nettle-mediated biosynthesis AgNPs indicated strong antibacterial activity against pathogenic microorganisms. Again, the antioxidant activity of AgNPs is quite high when compared to ascorbic acid. Anticancer effect of AgNPs, IC₅₀ dose was determined by XTT analysis using MCF-7 cell line and the IC₅₀ value was found to be 0.243 ± 0.014 μg/mL (% w/v).

Recent Advances in Nano-Enabled Seed Treatment Strategies for Sustainable Agriculture: Challenges, Risk Assessment, and Future Perspectives

Agro seeds are vulnerable to environmental stressors, adversely affecting seed vigor, crop growth, and crop productivity. Different agrochemical-based seed treatments enhance seed germination, but they can also cause damage to the environment; therefore, sustainable technologies such as nano-based agrochemicals are urgently needed. Nanoagrochemicals can reduce the dose-dependent toxicity of seed treatment, thereby improving seed viability and ensuring the controlled release of nanoagrochemical active ingredients However, the applications of nanoagrochemicals to plants in the field raise concerns about nanomaterial safety, exposure levels, and toxicological implications to the environment and human health. In the present comprehensive review, the development, scope, challenges, and risk assessments of nanoagrochemicals on seed treatment are discussed. Moreover, the implementation obstacles for nanoagrochemicals use in seed treatments, their commercialization potential, and the need for policy regulations to assess possible risks are also discussed. Based on our knowledge, this is the first time that we have presented legendary literature to readers in order to help them gain a deeper understanding of upcoming nanotechnologies that may enable the development of future generation seed treatment agrochemical formulations, their scope, and potential risks associated with seed treatment.

Review of functionalized nano porous membranes for desalination and water purification: MD simulations perspective

Today, it is known that most of the water sources in the world are either drying out or contaminated. With the increasing population, the water demand is increasing drastically almost in every sector each year, which makes processes like water treatment and desalination one of the most critical environmental subjects of the future. Therefore, developing energy-efficient and faster methods are a must for the industry. Using functional groups on the membranes is known to be an effective way to develop shorter routes for water treatment. Accordingly, a review of nano-porous structures having functional groups used or designed for desalination and water treatment is presented in this study. A systematic scan has been conducted in the literature for the studies performed by molecular dynamics simulations. The selected studies have been classified according to membrane geometry, actuation mechanism, functionalized groups, and contaminant materials. Permeability, rejection rate, pressure, and temperature ranges are compiled for all of the studies examined. It has been observed that the pore size of a well-designed membrane should be small enough to reject contaminant molecules, atoms, or ions but wide enough to allow high water permeation. Adding functional groups to membranes is observed to affect the permeability and the rejection rate. In general, hydrophilic functional groups around the pores increase membrane permeability. In contrast, hydrophobic ones decrease the permeability. Besides affecting water permeation, the usage of charged functional groups mainly affects the rejection rate of ions and charged molecules.

Advanced applications of sustainable and biological nano-polymers in agricultural production

Though still in its infancy, the use of nanotechnology has shown promise for improving and enhancing agriculture: nanoparticles (NP) offer the potential solution to depleted and dry soils, a method for the controlled release of agrochemicals, and offer an easier means of gene editing in plants. Due to the continued growth of the global population, it is undeniable that our agricultural systems and practices will need to become more efficient in the very near future. However, this new technology comes with significant worry regarding environmental contamination. NP applied to soils could wash into aquifers and contaminate drinking water, or NP applied to food crops may carry into the end product and contaminate our food supply. These are valid concerns that are not likely to be fully answered in the immediate future due to the complexity of soil-NP interactions and other confounding variables. Therefore, it is obviously preferred that NP used outdoors at this early stage be biodegradable, non-toxic, cost-effective, and sustainably manufactured. Fortunately, there are many different biologically derived, cost-efficient, and biocompatible polymers that are suitable for agricultural applications. In this mini-review, we discuss some promising organic nanomaterials and their potential use for the optimization and enhancement of agricultural practices.

Powerful and fast nanostructure electrochemical sensor for monitoring of carbidopa catechol-based drug in water and biological fluids

Herein, to monitor the concentration of carbidopa in an aqueous solution, an analytical approach based on electrode surface modification by Pt/SWCNTs as a sensor has been proposed. Pt/SWCNTs was synthesized by polyol strategy and characterized by the TEM method. Results confirmed spherical Pt nanoparticles with a diameter of about 10 nm decorated at the surface of SWCNTs with good distribution. The carbon paste electrode modified (CPEM) with Pt/SWCNTs was fabricated by mixing 12% of nanocomposite as an optimum condition with graphite powder in the presence of paraffin oil as a binder. Carbidopa's oxidation signal was enhanced by about 2.73 times when using the CPEM/Pt/SWCNTs, and its oxidation potential was decreased by about 110 mV. Additionally, the sensor demonstrated a linear dynamic range of 1.0 nM-120 M with a detection limit of 0.5 nM at pH = 7.0 as the ideal condition for monitoring carbidopa. Therefore, carbidopa in water and dextrose saline can be detected using CPEM/Pt/SWCNTs with an acceptable recovery range.

Different Impact of Suspended Al2O3 Nanoparticles on Microbial Communities: Formation of 2D-Networks (Without Humic Acids) or 3D-Colonies (With Humic Acids)

The use of metal-based and, particularly, Al₂O₃ nanoparticles (Al₂O₃-NP) for diverse purposes is exponentially growing. However, the growth of such promissory market is not accompanied by a parallel extensive investigation related to the impact of this pollution on groundwater and biological systems. Pseudomonas species, ubiquitous, environmentally critical microbes, frequently respond to stress conditions with diverse strategies that generally include extracellular polymeric substances (EPS) formation. The aim of this study is to report that changes in the aqueous environment, particularly, the addition of Al₂O₃-NP without and with humic acids, induce different adaptive strategies of Pseudomonas aeruginosa early biofilms. To this purpose, early biofilms were incubated in diluted culture media without (control) and with Al₂O₃-NP, and with humic acids (HA-control, HA-Al₂O₃-NP) for 24 h. 3D colonies with EPS strings and isolated bacteria in their surroundings were detected in the control biofilms. Unlikely, an unusual adaptive behaviour was developed in the presence of Al₂O₃-NP. Bacteria opt to disassemble the 3D arrangements and to implement a 2D network promoting morphological and size changes of bacterial cells (small coccoid shapes). Remarkably, this strategy allows their temporarily non-EPS-depending survival without decreasing the number of cells. This behaviour was not observed with ZnO-NP, HA-Al₂O₃-NP, or HA-ZnO-NP. Physicochemical analysis revealed that HA were adsorbed on Al₂O₃-NP and promoted the Al(III) ions complexation. This supports the hypothesis that the reduction of toxicity of Al ions and the 3D colony formation in the presence of HA-Al₂O₃-NP is promoted by the complexation of the metal ions with HA components.

Nano-technological interventions in crop production-a review

Agricultural industry is facing huge crisis due to fast changing climate, decreased soil fertility, macro and micronutrient insufficiency, misuse of chemical fertilizers and pesticides, and heavy metal presence in soil. With exponential increase in world's population, food consumption has increased significantly. Maintaining the production to consumption ratio is a significant challenge due to shortage caused by various issues faced by agricultural industry even with the improved agricultural practices. Recent scientific evidence suggests that nanotechnology can positively impact the agriculture sector by reducing the harmful effects of farming operations on human health and nature, as well as improving food productivity and security. Farmers are combining improved agricultural practices like usage of fertilizers, pesticides etc. with nano-based materials to improve the efficiency and productivity of crops. Nano technology is also playing a significant role improving animal health products, food packaging materials, and nanosensors for detecting pathogens, toxins, and heavy metals in soil among others. The nanobased materials have improved the productivity twice with half the resources being utilized. Nanoparticles that are currently in use include titanium dioxide, zinc oxide, silicon oxide, magnesium oxide, gold, and silver used for increasing soil fertility and plant growth. Crop growth, yield, and productivity are improved by controlled release nanofertilizers. In this review we elaborate on the recent developments in the agricultural sector by the usage of nanomaterial based composites which has significantly improved the agricultural sector especially how nanoparticles play an important role in plant growth and soil fertility, in controlling plant diseases by the use of nanopesticides, nanoinsecticides, nanofertilizers, Nanoherbicides, nanobionics, nanobiosensors. The review also highlights the mechanism of migration of nanoparticles in plants and most importantly the effects of nanoparticles in causing plant and soil toxicity.

Optimization of magnetic nano-iron production by Aspergillus flavipes MN956655.1 using response surface methodology and evaluation of their dye decolorizing and antifungal activities

Iron nanoparticles have been biosynthesized by a new Aspergillus flavipes isolate. Size of biosynthesized iron nanoparticles was in a range of 32.7 and 47.6 nm, their surface charge was - 33.5 ± 5.3 and they showed semihard ferromagnetic behavior. Salt concentration, volume of added culture filtrate and pH have been optimized using response surface methodology. A significant effect for the added culture filtrate and a mutual interaction between this factor and the pH has been detected. Model validation results showed 3.3% deviation from the statistically predicted values which reflects the accuracy of the employed model. Optimization process has increased the quantity of iron in the prepared samples and the amount of produced iron nanoparticles to a fourfold. The optimized conditions have stimulated the formation of nanoparticles in a tetrahedron shape rather than the truncated tetrahedron shape without affecting their size or surface charge. The biosynthesized iron nanoparticles have recorded a good decolorization activity for methylene blue. They showed 57 ± 4.3 decolorization percent after 6 h when tested with only 0.1 mg/ml concentration. Moreover, 50 ppm concentration has exerted a detectable antifungal activity against Alternaria solani. This study represents a new competitive green synthesis method for magnetic iron nanoparticle.

Mycosynthesis of Metal-Containing Nanoparticles-Fungal Metal Resistance and Mechanisms of Synthesis

In the 21st century, nanomaterials play an increasingly important role in our lives with applications in many sectors, including agriculture, biomedicine, and biosensors. Over the last two decades, extensive research has been conducted to find ways to synthesise nanoparticles (NPs) via mediation with fungi or fungal extracts. Mycosynthesis can potentially be an energy-efficient, highly adjustable, environmentally benign alternative to conventional physico-chemical procedures. This review investigates the role of metal toxicity in fungi on cell growth and biochemical levels, and how their strategies of resistance, i.e., metal chelation, biomineral formation, biosorption, bioaccumulation, compartmentalisation, and efflux of metals from cells, contribute to the synthesis of metal-containing NPs used in different applications, e.g., biomedical, antimicrobial, catalytic, biosensing, and precision agriculture. The role of different synthesis conditions, including that of fungal biomolecules serving as nucleation centres or templates for NP synthesis, reducing agents, or capping agents in the synthesis process, is also discussed. The authors believe that future studies need to focus on the mechanism of NP synthesis, as well as on the influence of such conditions as pH, temperature, biomass, the concentration of the precursors, and volume of the fungal extracts on the efficiency of the mycosynthesis of NPs.

Assessing the effect of SiO2 and TiO2 nanoparticles on granule stability and microbial community shift in aerobic granular sludge process

The widely used SiO₂ and TiO₂ nanoparticles (NPs) can accumulate in industrial wastewaters, thereby posing challenge to biological wastewater treatment processes. In this work, the performance of aerobic granular sludge (AGS) reactors fed with wastewater containing 50 mg L^-1 SiO₂ and TiO₂ NPs were investigated. The results showed that the granules could resist the NPs in wastewater (no disintegration of granules was observed). SiO₂ NPs had a negative effect on the settleability of granules, with the SVI₃₀ increased by 64.5% and protein secretion decreased by 29.9%. To the contrary, the settleability of granules was improved in the presence of TiO₂ NPs due to the increase of the protein secretion. Possibly because of the compact and layered structure of granules, in the presence of both types of NPs, no obvious reduction of the overall removal efficiency of organics was found, and nanoparticle-resistant strains were enriched. The overall nitrification and denitrification efficiencies were hardly affected by SiO₂ NPs while significantly inhibited by TiO₂ NPs. Some functional genera, such as Hyphomicrobium and Acidovorax, showed growth inhibition with TiO₂ NPs, which might be responsible for the reduction of nitrification and denitrification efficiencies.

Biosynthesized metal oxide nanoparticles for sustainable agriculture: next-generation nanotechnology for crop production, protection and management

The current agricultural sector is not only in its most vulnerable state but is also becoming a threat to our environment due to expanding population and growing food demands along with worsening climatic conditions. In addition, numerous agrochemicals presently being used as fertilizers and pesticides have low efficiency and high toxicity. However, the rapid growth of nanotechnology has shown great promise to tackle these issues replacing conventional agriculture industries. Since the last decade, nanomaterials especially metal oxide nanoparticles (MONPs) have been attractive for improving agricultural outcomes due to their large surface area, higher chemical/thermal stability and tunable unique physicochemical characteristics. Further, to achieve sustainability, researchers have been extensively working on ecological and cost-effective biological approaches to synthesize MONPs. Hereby, we have elaborated on recent successful biosynthesis methods using various plants/microbes. Furthermore, we have elucidated different mechanisms for the interaction of MONPs with plants, including their uptake/translocation/internalization, photosynthesis, antioxidant activity, and gene alteration, which could revolutionize crop productivity/yield through increased nutrient amount, photosynthesis rate, antioxidative enzyme level, and gene upregulations. Besides, we have briefly discussed about functionalization of MONPs and their application in agricultural-waste-management. We have further illuminated recent developments of various MONPs (Fe₂O₃/ZnO/CuO/Al₂O₃/TiO₂/MnO₂) as nanofertilizers, nanopesticides and antimicrobial agents and their implications for enhanced plant growth and pest/disease management. Moreover, the potential use of MONPs as nanobiosensors for detecting nutrients/pathogens/toxins and safeguarding plant/soil health is also illuminated. Overall, this review attempts to provide a clear insight into the latest advances in biosynthesized MONPs for sustainable crop production, protection and management and their scope in the upcoming future of eco-friendly agricultural nanotechnology.