This application claims the benefit of priority from Brazilian Patent Application No. 1320210199287, filed Oct. 4, 2021, which is incorporated herein by reference.
This document constitutes a Certificate of Addition to patent application BR1020200163620, entitled “NANOSTRUCTURED HYBRID MATERIAL BASED ON NIOBIUM OLIGOMERS, OBTENTION METHOD AND USE”, filed on Aug. 11, 2020, and relates to nanostructured materials based on in niobium oligomers, organic cations, quaternary ammonium salts and copper cations (Cu2+) with high foliar antifungal activity, which can also be used as biomarkers.
Fungal diseases are increasingly recognized as a global threat to food security and biodiversity. This is related to the fact that fungi are very resistant microorganisms that destroy crops and animal species. Although this problem is not new, fungal diseases still pose a widespread threat to various plant species, mainly wheat, corn, rice, potato and soybeans. It is estimated that at least 125 million tons of food are destroyed by fungal diseases each year. Environmental, genetic and biological factors directly or indirectly affect plant vitality (Matthew C. Fisher et al., “Emerging fungal threats to animal, plant and ecosystem health” Nature, 484(7393), 186-194, 2012).
Fungi act as pathogens based on their form of nutrition. The three main forms of action are (i) biotrophs, which survive by parasitizing the living tissue of the plant, necrotrophs, which feed on dead plant tissues, and (iii) hemibiotrophs, which initiate infection by feeding on plants. Fungal diseases are often controlled with the use of synthetic fungicides in agriculture However, prior identification of the pathogen is necessary, so that effective chemicals are used. Several fungicides are potential compounds against foliar pathogens, but these products are not ideal long-term solutions due to high cost, environmental and human health impacts. In addition, the evolution of phytopathogen resistance is considered a major problem in agriculture, and therefore, the development of new safe, effective and ecological pest control and management agents becomes urgent (Aly Derbalah et al., “Antifungal activity of fabricated mesoporous silica nanoparticles against early blight of tomato” Egyptian Journal of Basic and Applied Sciences, 5(2), 2018).
The development of nanotechnology can contribute to obtaining new agents for the detection and control of fungal diseases in plants. Nanoparticles, especially of metals and metal oxides, due to their reduced dimensions and large surface areas, have particular electronic, mechanical, magnetic and chemical properties. In this sense, the application of these nanometric compounds is already recognized in the areas of catalysis, photonics, biosensors and optoelectronics, and, recently, they have been highlighted in agricultural applications acting as antibacterial and antifungal agents (Aly Derbalah et al., “Antifungal activity of manufactured mesoporous silica nanoparticles against early blight of tomato” Egyptian Journal of Basic and Applied Sciences, 5(2), 2018) (L.A. Hermida-Montero et al., “Aqueous-phase synthesis of nanoparticles of copper/copper oxides and their antifungal effect against Fusarium oxyporum” Journal of Hazardous Materials, 38, 120850, 2019).
In general, metallic semiconductor nanoparticles, such as niobium nanoparticles, act as a fungicide through the production of reactive oxygen species (ROS). The ROS generated interfere with metabolic processes that damage cell components such as DNA, proteins and enzymes, which reduces spore viability. It is well known that the generated ROS causes cellular oxidative stress. In this case, an oxidant/antioxidant imbalance is created and consequently leads to membrane lipid degradation, leading to cell death (Dayem, A. A., et al., “The Role of Reactive Oxygen Species (ROS) in the Biological Activities of Metallic Nanoparticles” International Journal of Molecular Sciences, 18(1), 120, 2017).
Patent document BR102015025650, the priority date of which is Oct. 7, 2015, entitled “Process for producing material comprising titanium dioxide with a surface modified with peroxo groups, said material applicable in heterogeneous catalysis processes under ultraviolet and visible radiation and use of said material as a bactericidal and antifungal agent, among other uses”, describes obtaining materials based on titanium dioxide, whose surface is modified with peroxide groups that have photocatalytic activity, and that can be used as a bactericidal and antifungal agent.
The paper entitled “Aqueous-phase synthesis of nanoparticles of copper/copper oxides and their antifungal effect against Fusarium oxyporum” (L. A. Hermida-Montero et al., Journal of Hazardous Materials, 38, 120850, 2019) shows the synthesis of nanoparticles of copper and copper oxide with antifungal action against the fungus Fusarium oxyporum. The nanoparticles were obtained from the precipitation method with NaBH4 solution.
In the state of the art, the use of anionic niobium species as foliar fungicides or biomarkers was not found.
The present technology relates to a compound based on anionic niobium nanoparticles that has the ability to contain the growth of fungi in plants. The compound fights the foliar fungi present in the plant, allowing better productivity. Its advantages compared to the state of the art are the use of commercial niobium compounds to obtain polyoxoniobates which are combined with non-toxic organic species and/or Cu2+ cations to improve their fungicidal action. In the state of the art, there is no report of the use of niobium compounds with fungicidal activity for application in agriculture. Therefore, another commercial application is proposed for this important chemical element, which is currently mostly used in the metallurgical industry.
The present technology relates to nanostructured materials based on niobium oligomers, organic cations, quaternary ammonium salts and copper cations (Cu2+) with high foliar antifungal activity, and can also be used as biomarkers, and their respective obtention methods.
The fungicides and markers based on niobium oligomers comprise anionic niobium oligomers and cations selected from the group comprising quaternary ammonium salts, cationic methylene blue, or Cu2+ salts in a ratio between 1:1, 2:1 or 1:2 from niobates to cations.
Niobium oligomers can be obtained from the leaching of commercial niobium compounds selected from the group comprising niobium oxide, niobium pentoxide, niobic acid and niobium phosphate.
Quaternary ammonium salts can be selected from the group comprising hexadecyltrimethylammonium bromide (CTAB), alkyl dimethyl benzyl ammonium chloride, stearyl dimethyl ammonium chloride, cetyl trimethyl ammonium chloride, hexadecyltrimethyl ammonium bromide and cetyl trimethyl ammonium bromide.
Cu2+ salts can be selected from the group comprising copper hydroxide, copper oxychloride, copper chloride, cuprous oxide, copper nitrate, copper sulfate or tribasic copper sulfate.
The process of obtaining the fungicide comprises the following steps:
Niobium oligomers can be obtained from the leaching of commercial niobium compounds selected from the group comprising niobium oxide, niobium pentoxide, niobic acid and niobium phosphate.
Quaternary ammonium salts can be selected from the group comprising alkyl dimethyl benzyl ammonium chloride, stearyl dimethyl ammonium chloride, cetyl trimethyl ammonium chloride, hexadecyltrimethyl ammonium bromide (CTAB) and cetyl trimethyl ammonium bromide.
Cu2+ salts can be selected from the group comprising copper hydroxide, copper oxychloride, cuprous oxide, copper chloride, copper nitrate, copper sulfate and tribasic copper sulfate.
After obtaining the fungicidal solutions based on nanostructures of niobium with cations, they can be dripped on the leaves of the plants to prevent the proliferation of fungi. Furthermore, X-ray diffraction results indicated that the niobium fungicide can also be used as a marker and tracer, being able to identify crops in which the compound was used, monitor seeds and areas of illegal deforestation.
Niobium nanoparticles in combination with cations were significantly more fungicidal than niobium nanoparticles alone. In the present study, synergism between both components is evident. The combination of niobium nanoparticles and cations facilitates increasing the bioavailability of niobium nanoparticles by increasing the amount of this material in direct contact with the fungal membrane or by mechanisms that modulate the availability of the nanoparticle within the fungal cell. It is known that the direct contact of positively charged nanoparticles with the membrane of microorganisms occurs by electrostatic attraction with the highly negative charge of the cell surface. However, the niobium nanoparticles in the present study are negatively charged and, as a consequence, the repulsion of the negative charges present in the fungal cells is expected. Thus, the use of cations, combined with anionic niobium species, may be responsible for reducing the negative charge of nanoparticles, promoting the attachment of these particles to the fungal cell surface (Malandrakis A. A. et al., “Use of silver nanoparticles to counter fungicide—resistance in Monilinia fructicola: Science of The Total Environment, 747, 141287, 2020).
The present technology can be better understood through the following non-limiting examples.
The different formulations of fungicides were obtained from the mixture of 1.0 g of polyoxoniobates with 1000 mL of water. From this solution, three formulations of fungicides were prepared, the first, from the addition of 100 ml of cationic methylene blue at a concentration of 1000 mg/L, the second, from the addition of 100 ml of copper chloride at a concentration of 1000 mg/L and the third from the addition of 100 ml of cetyltrimethylammonium bromide at a concentration of 1000 mg/L. In
In order to characterize the material obtained, the fungicide solution based on niobium with copper was analyzed by spectrometry in the UV-Vis region. The analysis was performed in a UV-Vis spectrometer (Shimadzu-2600/2700) with scanning performed between 200-800 nm. The graph obtained can be seen in
Tomatoes were cultivated in a small area and evaluated for 40 days. After 40 days some fungal diseases were identified in the analyzed tomato plants according to the aspect that the leaves, branches and fruits presented. In a) of
Niobium-based compounds with and without cetyltrimethylammonium bromide (CTAB) with fungicidal potential were applied since tomato flowering. It was noted that the leaves presented healthy aspects and it was no longer possible to observe signs of infection indicating that the molecules sprayed weekly protect the crops from the action of fungi. In
This product not only acted in the elimination of fungi on tomato leaves, but also in the recovery of the roots and fruits of the plants. The fungal disease can also attack the roots and fruits of tomato plants, making them weak and vulnerable. In this sense, it can be seen in d) of
In order to confirm and quantify the fungicidal effect based on niobium, fungicides with polyoxoniobates combined with Cu2+, with CTAB and with methylene blue were tested on soybean leaves. Experiments were carried out to induce the growth of the fungus Phakopsora pachyrhizi responsible for the onset of the Asian Rust disease and responsible for a large part of productivity losses in soybean crops.
The experiments were carried out in 3 Petri dishes with 4 leaflets (folioles)/plate. The spore suspension at an approximate concentration of 105 spores/mL was applied to the unifolioles. Then, the plates were incubated for a period of 14 days, in conditions of high humidity, photoperiod of 12 h and temperature of 24° C.
The LC50 results (concentration needed to eliminate 50% of the fungus) show the efficiency of the niobium product combined with cations: 0.53 mg/L for polyoxoniobates with Cu2+, 1.13 mg/L for polyoxoniobates with methylene blue and 1.09 mg/L for polyoxoniobates with CTAB. It should be emphasized that, for the niobium compound without the cations, the LC50 result obtained was 4.11 mg/L. It can be noted that niobium nanoparticles in combination with cations were significantly more fungitoxic than niobium nanoparticles alone. In the present study, synergism between both components is evident. The combination of niobium nanoparticles and cations probably promotes increased bioavailability of niobium nanoparticles by increasing the amount of this material in direct contact with the fungal membrane or by mechanisms that modulate the availability of the nanoparticle inside the fungal cell.
In addition, data for a commercial compound (Prothioconazole) widely used by soybean producers showed an LC50 of 0.50 mg/L. The results obtained for the niobium materials in the present invention show its fungicidal potential and indicate its use with more efficiency since it does not exhibit toxicity and, unlike commercial compounds, it is soluble in water, making the application process less expensive. The copper-containing compound was the closest to the commercial one, and the reason for the best effect is indicated in
Using a portable X-ray diffractometer, it was possible to identify the presence of niobium on the leaves. In
Number | Date | Country | Kind |
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1320210199287 | Oct 2021 | BR | national |