Nanoparticles and biochar with adsorbed plant growth-promoting rhizobacteria alleviate Fusarium wilt damage on tomato and watermelon.

The addition of biochars and nanoparticles with adsorbed Azotobacter vinelandii and Bacillus megaterium alleviated damage from Fusarium infection in both tomato (Solanum lycopersicum) and watermelon (Citrullus lanatus) plants. Tomato and watermelon plants were grown in greenhouse for 28 and 30 days (respectively) and were treated with either nanoparticles (chitosan-coated mesoporous silica or nanoclay) or varying biochars (biochar produced by pyrolysis, gasification and pyrogasification). Treatments with nanoparticles and biochars were applied in two variants - with or without adsorbed plant-growth promoting bacteria (PGPR). Chitosan-coated mesoporous silica nanoparticles with adsorbed bacteria increased chlorophyll content in infected tomato and watermelon plants (1.12 times and 1.63 times, respectively) to a greater extent than nanoclay with adsorbed bacteria (1.10 times and 1.38 times, respectively). However, the impact on other endpoints (viability of plant cells, phosphorus and nitrogen content, as well antioxidative status) was species-specific. In all cases, plants treated with adsorbed bacteria responded better than plants without bacteria. For example, the content of antioxidative compounds in diseased watermelon plants increased nearly 46% upon addition of Aries biochar and by approximately 52% upon addition of Aries biochar with adsorbed bacteria. The overall effect on disease suppression was due to combination of the antifungal effects of both nanoparticles (and biochars) and plant-growth promoting bacteria. These findings suggest that nanoparticles or biochars with adsorbed PGPR could be viewed as a novel and sustainable solution for management of Fusarium wilt.

Biologically synthesized zinc and copper oxide nanoparticles using Cannabis sativa L. enhance soybean (Glycine max) defense against fusarium virguliforme.

In this study, zinc and copper oxide nanoparticles (NPs) were synthesized using hemp (Cannabis sativa L.) leaves (ZnONP-HL and CuONP-HL), and their antifungal potential was assessed against Fusarium virguliforme in soybean (Glycine max L.). Hemp was selected because it is known to contain large quantities of secondary metabolites that can potentially enhance the reactivity of NPs through surface property modification. Synthesizing NPs with biologically derived materials allows to avoid the use of harsh and expensive synthetic reducing and capping agents. The ZnONP-HL and CuONP-HL showed average grain/crystallite size of 13.51 nm and 7.36 nm, respectively. The biologically synthesized NPs compared well with their chemically synthesized counterparts (ZnONP chem, and CuONP chem; 18.75 nm and 10.05 nm, respectively), confirming the stabilizing role of hemp-derived biomolecules. Analysis of the hemp leaf extract and functional groups that were associated with ZnONP-HL and CuONP-HL confirmed the presence of terpenes, flavonoids, and phenolic compounds. Biosynthesized NPs were applied on soybeans as bio-nano-fungicides against F. virguliforme via foliar treatments. ZnONP-HL and CuONP-HL at 200 µg/mL significantly (p < 0.05) increased (∼ 50%) soybean growth, compared to diseased controls. The NPs improved the nutrient (e.g., K, Ca, P) content and enhanced photosynthetic indicators of the plants by 100-200%. A 300% increase in the expression of soybean pathogenesis related GmPR genes encoding antifungal and defense proteins confirmed that the biosynthesized NPs enhanced disease resistance against the fungal phytopathogen. The findings from this study provide novel evidence of systemic suppression of fungal disease by nanobiopesticides, via promoting plant defense mechanisms.

Engineered Nanoparticles, Natural Nanoclay and Biochar, as Carriers of Plant-Growth Promoting Bacteria.

The potential of biochar and nanoparticles to serve as effective delivery agents for beneficial bacteria to crops was investigated. Application of nanoparticles and biochar as carriers for beneficial bacteria improved not only the amount of nitrogen-fixing and phosphorus-solubilizing bacteria in soil, but also improved chlorophyll content (1.2-1.3 times), cell viability (1.1-1.5 times), and antioxidative properties (1.1-1.4 times) compared to control plants. Treatments also improved content of phosphorus (P) (1.1-1.6 times) and nitrogen (N) (1.1-1.4 times higher) in both tomato and watermelon plants. However, the effect of biochars and nanoparticles were species-specific. For example, chitosan-coated mesoporous silica nanoparticles with adsorbed bacteria increased the phosphorus content in tomato by 1.2 times compared to a 1.1-fold increase when nanoclay with adsorbed bacteria was applied. In watermelon, the situation was reversed: 1.1-fold increase in the case of chitosan-coated mesoporous silica nanoparticles and 1.2 times in case of nanoclay with adsorbed bacteria. Our findings demonstrate that use of nanoparticles and biochar as carriers for beneficial bacteria significantly improved plant growth and health. These findings are useful for design and synthesis of novel and sustainable biofertilizer formulations.

Novel franklinite-like synthetic zinc-ferrite redox nanomaterial: synthesis, and evaluation for degradation of diclofenac in water.

The current study investigates a novel redox technology based on synthetic franklinite-like zinc-ferrite nanomaterial with magnetic properties and redox nature for potential use in water treatment. Physicochemical characterization revealed the nanoscale size and AB2O4 spinel configuration of the zinc-ferrite nanomaterial. The redox activity of nanoparticles was tested for degradation of diclofenac (DCF) pharmaceutical in water, without any added external oxidants and under dark experimental conditions. Results revealed ~90% degradation in DCF (10 µM) within 2 min of reaction using 0.17 g/L Zn1.0Fe2.0O4. Degradation of DCF was due to chemical reduction by surface electrons on zinc-ferrite and oxidation by oxygen-based radicals. Three byproducts from reduction route and eight from oxidation pathways were identified in the reaction system. Reaction pathways were suggested based on the identified byproducts. Results demonstrated the magnetic zinc-ferrite is a standalone technology that has a great promise for rapid degradation of organic contaminants, such as DCF in water.

Photochemical treatment of tyrosol, a model phenolic compound present in olive mill wastewater, by hydroxyl and sulfate radical-based advanced oxidation processes (AOPs).

The photochemical degradation and mineralization of tyrosol (TSL), a model phenolic compound present in olive mill wastewater, were studied by UV-254 nm irradiated peroxymonosulfate (PMS), hydrogen peroxide (H2O2) and persulfate (PS). Effects of initial TSL concentration, UV fluence, pH, phosphate buffer and presence of inorganic anions (i.e., Cl-, SO42- and NO3-) were also investigated. Sulfate and hydroxyl radicals were demonstrated to be responsible for TSL degradation and mineralization. Regardless of the treatment conditions, pseudo-first-order kinetics could be obtained, with the efficiencies following UV/PS > UV/H2O2 > UV/PMS. The better removal of TSL by UV/PS correlated with the quantum yield and concentration of sulfate radical in the system. Albeit acidic condition slightly enhanced the performance of the AOPs, complete oxidation of TSL was achieved at pH 6.8 by both UV/PS and UV/H2O2. Though, inorganic anions or different concentrations of phosphate buffer did not affect TSL degradation kinetics, presence of inorganic ions decreased significantly the TOC removal for both UV/PMS and UV/H2O2 processes. Meanwhile, UV/PS process was the least influenced by inorganic ions and showed the highest TOC removal of ∼35%. Overall, UV/PS process was the most effective for TSL degradation and mineralization in the presence or absence of common water constituents.

Analysis of metallic and metal oxide nanomaterial environmental emissions.

The current study presents evidence on metallic and metal oxide engineered nanomaterial (ENM) emissions into the environment and an analytic perspective of the outcomes of evaluated studies with respect to different individual end points along the lifecycle trajectory. The key findings suggest that 1) the published literature on emissions of metallic ENMs is limited in both the number and information available on the characteristics of emitted ENMs; 2) the studies are classified as experimental and computational studies focused on predicting ENM emissions; 3) the majority of studies investigated ENM emissions during nanomaterial use and waste management, followed by raw material manufacturing, and finally, nano-enabled product manufacturing; 4) the studies primarily reported the concentration/quantity of emitted ENMs, whereas the physical-chemical characteristics of emitted ENMs were rarely measured or reported; and 5) the published literature primarily focused on emissions of silver and titanium dioxide ENMs and lacked similar information on other surging metallic and metal oxide ENMs such as nano-zero valent iron (nZVI), aluminum (Al), and aluminum oxide (Al2O3) ENMs. The evidence suggests that emitted nanoparticles into the air cover a wide range of concentrations below and above the allowable occupational exposure limits. The concentrations of nanoparticles in water systems are considered in the toxic to very toxic range for a variety of biological species. Given the critical gaps in knowledge, one cannot read across different sources of emissions for metallic and metal oxide ENMs hampering efforts with respect to understanding realistic scenarios for transformations in the natural environment and biological media.

The effects of metallic engineered nanoparticles upon plant systems: An analytic examination of scientific evidence.

Recent evidence for the effects of metallic engineered nanoparticles (ENPs) on plants and plant systems was examined together with its implications for other constituents of the Society-Environment-Economy (SEE) system. In this study, we were particularly interested to determine whether or not metallic ENPs have both stimulatory and inhibitory effects upon plant performance. An emphasis was made to analyze the scientific evidence on investigations examining both types of effects in the same studies. Analysis of evidence demonstrated that metallic ENPs have both stimulatory and inhibitory effects mostly in well-controlled environments and soilless media. Nano zero-valent iron (nZVI) and Cu ENPs have potential for use as micronutrients for plant systems, keeping in mind the proper formulation at the right dose for each type of ENP. The concentration levels for the stimulatory effects of Cu ENPs are lower than for those for nZVI. Newer findings showed that extremely smaller concentrations of Au ENPs (smaller than those for nZVI and Cu ENPs) induce positive effects for plant growth, which is attributed to effects on secondary metabolites. Ag ENPs have demonstrated their usage as antimicrobial/pesticidal agents for plant protection; however, precautions should be taken to avoid higher concentrations not only for plant systems, but also, other constituents in the SEE. Further research is warranted to investigate the stimulatory and inhibitory effects of metallic ENPs in soil media in order to broaden the horizon of sustainable agriculture production in terms of higher and safer yields so as to meet the food requirements of human population.

The path towards healthier societies, environments, and economies: a broader perspective for sustainable engineered nanomaterials.

Economic value is no longer adequate by itself as a proxy for the value-added benefits (VAB) assumed to be generated by emerging technologies such as engineered nanomaterials (ENMs). This study was conducted to explore the potential to establish an integrated sociotechnical framework with the end goal to assess whether or not ENMs and nano-enabled products contribute VAB. Based on the research in this study, it is suggested that all stakeholders in the larger society-environment-economy (SEE) system should develop an understanding of the multiple interrelationships within and between the diverse constituents along the particle lifecycle trajectory to capture their influence on the system benefit and risk outcomes. Furthermore, the sociotechnical framework establishes an additional three-step process: (1) at the pre-design stage, the test of VAB should be assessed using an expert panel representing the different segments of SEE, the social principles of design are detailed and customized to the needs of ENMs and nano-enabled products, and an economic appraisal is conducted to justify the VAB on material grounds; (2) at the design stage, the technical principles should be examined and detailed to ensure the compatibility of stakeholder needs; and (3) an iterative adaptive cycle should be conducted to re-examine the sociotechnical principles on a periodic basis. Within this context, ENMs are considered sustainable when (a) the conditions of VAB and minimal risk elements are satisfied in a sequential order, with VAB demonstrated at the pre-design stage, then at the design stage ENMs posing no harm greater than minimal levels to the SEE constituents; and (b) ENMs and nano-enabled products are bounded by a finite time limit. In addition, to reach the conditions of sustainability, the role of all SEE stakeholders should be broadened (e.g., regulatory agencies should transform their roles from not only the control of risks of negative implications, but also the establishment of positive implications as well).

Degradation and mineralization of organic UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) using UV-254nm/H2O2.

Various studies have revealed the non-biodegradable and endocrine disrupting properties of sulfonated organic UV absorbers, directing people's attention toward their risks on ecological and human health and hence their removal from water. In this study, UV-254nm/H2O2 advanced oxidation process (AOP) was investigated for degrading a model UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and a structurally similar compound 1H-benzimidazole-2-sulfonic acid (BSA), with a specific focus on their mineralization. At 4.0mM [H2O2]0, a complete removal of 40.0µM parent PBSA and 25% decrease in TOC were achieved with 190min of UV irradiation; SO4(2-) was formed and reached its maximum level while the release of nitrogen as NH4(+) was much lower (around 50%) at 190min. Sulfate removal was strongly enhanced by increasing [H2O2]0 in the range of 0-4.0mM, with slight inhibition in 4.0-12.0mM. Faster and earlier ammonia formation was observed at higher [H2O2]0. The presence of Br(-) slowed down the degradation and mineralization of both compounds while a negligible effect on the degradation was observed in the presence of Cl(-). Our study provides important technical and fundamental results on the HO based degradation and mineralization of SO3H and N-containing UV absorber compounds.