Compositions having variable hydrophobicity and coatings comprising same

Abstract

The present disclosure provides compositions including a carrier and an element. The carrier includes starch and the element is covalently bonded to the carrier. A water droplet contact angle of the composition is greater than a water droplet contact angle of starch under the same conditions and after the same elapsed time up to one hours. The compositions may be used as a coating, such as for a seed or fertilizer particle, or may be added to soil for delivery of the element in biologically available form to a plant.

Description

COMPOSITIONS HAVING VARIABLE HYDROPHOBICITY AND COATINGS COMPRISING SAMEFIELD

[0001] This invention relates to compositions having variable hydrophobicity and coatings comprising same. In particular, the invention relates to compositions including a carrier comprising starch, and an element, wherein the element is covalently bonded to the carrier. Also provided are methods for preparing such compositions.BACKGROUND

[0002] In modern agriculture, nutrients are applied to soils to maximize the growth of plants. However, a significant proportion of nutrients simply wash away from the soils because they are water soluble. For example, rain and irrigation may cause applied nutrients to move vertically through the soil and away from plant roots, thereby limiting or prohibiting nutrient uptake by plants. Another issue with nutrient solubility in soils is agricultural run-off, which is a major contributor to the eutrophication of fresh water bodies. Phosphate, a common fertilizer, may promote the growth of cyanobacteria and algae in water bodies, which in turn can produce harmful toxins and cause a depletion of oxygen.

[0003] Trace metals, such as iron, zinc, copper, boron and magnesium, are also important components of soil chemistry that may be depleted by environmental effects and crop uptake, resulting in decreased crop yields. Trace mineral depletion may be caused by NPK fertilizers, which are known to dilute the concentrations of other nutrients in plants. Although NPK fertilizers improve crop yields, their use combined with progressively higher-yielding crop varieties may produce foods with lower mineral and nutrient concentrations than their less productive ancestors (Henkel M. Sustainable Agriculture III: Agricultural Practices. 2005; 18-19).

[0004] Trace metal deficiency in soil may be mitigated by replacing trace metals in soil; however, trace metal leaching limits the efficacy of fertilizers that contain these nutrients. Furthermore, over application of trace metals may result in reduced crop growth or crop mortality (Kampfenkel K, Van Montagu M, Inze D. Effects of Iron Excesson Nicotiana plumbaginifolia Plants (Implications to Oxidative Stress). Plant Physiology. 1995; 107(3):725-735). As a result, application of trace metals to soils must be done carefully and must avoid local areas of high concentration.

[0005] For example, US8,642,507 discloses a fertilizer formulation for the reduction of nutrient and pesticide leaching. Semi-soluble decomposable polymers are used which release nutrients continuously in the presence of water. However, these formulations release the nutrients regardless of biological demand.

[0006] Trace metals should also be present in bioavailable form. Some trace metals, such as boron, are bioavailable in their common state, but others are not. Several factors may reduce the bioavailability of some trace metals if they are applied directly to the soil. For example, plants typically utilize iron as ferrous iron (Fe2+). However, in soil, some trace metals are present as positively charged metal ions and will readily react with oxygen and / or negatively charged hydroxyl ions (OH-). If they react with oxygen or hydroxide ions, they form new compounds such as ferric ion (Fe3+) that are less bioavailable to plants. Both oxygen and hydroxide ions are abundant in soil and soilless growth media.

[0007] Agricultural fertilizers, which are generally water-soluble, are frequently coated with polymers to control the rate at which the fertilizer dissolves in soils. However, the polymers used to coat the fertilizers are a source of agricultural microplastic (MP) pollution. MPs are generally recognized as plastic fragments with a size smaller than 5 mm.

[0008] MP pollution has become a global environmental issue. MPs can enter into agricultural soils mainly through the application of biosolids, wastewater irrigation, film mulching, polymer-based fertilizers and atmospheric deposition. Due to their small particle size, high specific area and persistence, MPs are considered to be easily taken up or adsorbed by plants and soil organisms, posing an ecological risk to the agricultural environment and human health.

[0009] In recent years, and compared with non-biodegradable or incompatible particle stabilizers such as silica, alumina, clay particles and titanium oxides, environment-friendly starch as a particle stabilizer has attracted wider interest in various Pickering emulsions. Modified starches with hydrophobicity are also widely used in thepharmaceutical industry due to their wide variety of sources, non-toxicity, biocompatibility and biodegradation. However, the inherent hydrophilicity of starch has greatly limited its application in this industry.

[0010] Thus, there remains a need for a material that retains elements such as nutrients in a bioavailable form, does not leach elements into its surroundings until sequestered through biological demand, is non-toxic, and is not a source of MP pollution. Furthermore, there is also a need for a material that can be used as a coating which is not a source of MP pollution, is non-toxic and increases the hydrophobicity of the coated material.SUMMARY

[0011] In one aspect, the present disclosure provides compositions for use in delivering an element to a plant in response to biological demand, and for use as coatings. Also provided are methods of making such compositions.

[0012] Various aspects of the present disclosure provide a composition comprising a carrier comprising starch; and an element, wherein the element is covalently bonded to the carrier, and wherein a water droplet contact angle of the composition is greater than a water droplet contact angle of starch under the same conditions and after the same elapsed time up to one hour.

[0013] In various embodiments, the composition is insoluble in water.

[0014] In various embodiments, the carrier is soluble or partially soluble in water.

[0015] In various embodiments, a salt of the element is soluble or partially soluble in water.

[0016] In various embodiments, the element is a nutrient for plant growth.

[0017] In various embodiments, the element is a cation.

[0018] In various embodiments, the element is Fe2+, Fe3+, Mn2+, Cu+, Cu2+, Ca2+, Mg2+, Mo4+, Mo6+or Zn2+.

[0019] In various embodiments, the carrier comprises at least about 20% starch. For example, the carrier may comprise at least about 60% starch. For example, the carrier may comprise at least about 70% starch.

[0020] In various embodiments, the water droplet contact angle of the composition is at least 20° greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 1600 seconds.

[0021] In various embodiments, the water droplet contact angle of the composition is at least 20° greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 3960 seconds.

[0022] In various embodiments, the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions.

[0023] In various embodiments, the water droplet contact angle of the composition is between 90° and 160° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions.

[0024] In various embodiments, the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 1600 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 1600 seconds and under the same conditions.

[0025] In various embodiments, the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 3960 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 3960 seconds and under the same conditions.

[0026] In various embodiments, the water droplet contact angle of the composition is between 90° and 160° at an elapsed time of 1600 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 1600 seconds and under the same conditions.

[0027] In various embodiments, the water droplet contact angle of the composition is between 90° and 160° at an elapsed time of 3960 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 3960 seconds and under the same conditions.

[0028] In various embodiments, the water droplet contact angle of the composition is greater than 90° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions.

[0029] In various embodiments, the water droplet contact angle of the composition is greater than 20° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions.

[0030] In various embodiments, the water droplet contact angle of the composition is greater than 20° at an elapsed time of one hour, compared to starch, which has a contact angle of 0° at the elapsed time of one hour and under the same conditions.

[0031] In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and at an elapsed time of 10 seconds.

[0032] In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and at an elapsed time of 1600 seconds.

[0033] In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and at an elapsed time of 3960 seconds.

[0034] In various embodiments, the water droplet contact angle of the composition is at least 60° greater than the water droplet contact angle of starch under the same conditions and at an elapsed time of 10 seconds.

[0035] In various embodiments, the composition has a moisture content of about 40% (wt / wt) or less. For example, the composition may have a moisture content of about 10% (wt / wt) or less.

[0036] In various embodiments, the composition comprises at least about 5% (wt / wt) of the element, based on the total weight of the composition.

[0037] In various embodiments, the composition comprises between about 1% and about 17% (wt / wt) of the element, based on the total weight of the composition. For example, the composition may comprise between about 1 % and about 5% (wt / wt) of the element, based on the total weight of the composition.

[0038] In various embodiment, the carrier is pea starch, lentil starch, oat starch, potato starch, sweet potato starch, corn starch, bean starch, cassava starch, wheat starch, rice starch, sorghum starch, millet starch, taro starch, yam starch, arrow root starch, sago palm starch, plantains starch, banana starch, squash starch or a combination thereof.

[0039] In various embodiments, the composition is for use as a coating. For example, the composition may be used as a coating for a seed or for a fertilizer particle.

[0040] Various aspects of the present disclosure also provide a method for delivering an element to an organism, the method comprising adding a composition as disclosed herein to an environment of the organism. In various embodiments, the environment is soil and the organism is a plant.

[0041] Various aspects of the present disclosure also provide a method for preparing a composition as disclosed herein, the method comprising: mixing a base in a solvent to form a mixture; spraying the mixture on a carrier comprising starch and mixing to form a starch mixture; adding a salt or an ionic salt of an element to form an element mixture, spray the element mixture with water to form a product mixture; and stirring, heating and drying the product mixture to a moisture content of about 40% (wt / wt) or less to form the composition.

[0042] In various embodiments, the heating is conducted between about 20°C and about 80°C.

[0043] In various embodiments, an amount of the base in the mixture is about 1 .0 g / mL to about 1 .5 g / mL.

[0044] In various embodiments, an amount of the salt or the ionic salt of the element in the element mixture is about 0.3 g / mL to about 0.7 g / mL.

[0045] In various embodiments, the solvent is water.

[0046] In various embodiments, the base is potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydroxide, ammonium hydroxide or a combination thereof. For example, the base may be potassium hydroxide. In various embodiments, the hydroxide groups may also be deprotonated by an electrochemical surface activation method.

[0047] In various embodiments, the salt or the ionic salt of the element is ZnSO4, Fe2O3, CuSCM, MnSCM, ZnCl2, FeCh, MnCl2, FeSO4, CuCl2, MnCl2, ZnO, ZnCOs, MgSCM, MgCl2, FeCOs, Fe2(CO3)3, MnCOs, Zn(PO4)2, Mn3(PO4)2 or a combination thereof. For example, the salt or the ionic salt of the element may be ZnSO4, Fe2Os or CuSCM.

[0048] In various embodiments, about 10% to about 25% (wt / wt) base to total weight of the carrier is used in the method.

[0049] In various embodiments, about 25% to about 50% (wt / wt) base to total weight of the salt or the ionic salt of the element is used in the method. For example, about 30% to about 45% (wt / wt) base to total weight of the salt or the ionic salt of the element is used in the method.

[0050] In various embodiments, about 5% to about 55% (wt / wt) salt or ionic salt of the element to total weight of the carrier is used in the method.

[0051] Various aspects of the present disclosure also provide a coating comprising a composition as described herein.

[0052] Various aspects of the present disclosure also provide a seed coated with a composition as described herein.

[0053] Various aspects of the present disclosure also provide a fertilizer particle coated with a composition as described herein.

[0054] Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In drawings which illustrate embodiments of the disclosure,

[0056] Figure 1 shows a SEM-EDS image of a zinc-starch composition as disclosed herein.

[0057] Figure 2 shows a SEM-EDS image of an iron-starch composition as disclosed herein.

[0058] Figure 3 shows a SEM-EDS image of a copper-starch composition as disclosed herein.

[0059] Figure 4 shows a SEM-EDS image of a manganese-starch composition as disclosed herein.

[0060] Figure 5 shows a water droplet contact angle comparison between untreated starch (left side) and an iron-starch composition as disclosed herein (right side) at an elapsed time of 0 seconds.

[0061] Figure 6 shows a water droplet contact angle comparison between untreated starch and the compositions prepared according to Examples 1-4 at elapsed times of time = 0 seconds, time = 1 second, time = 10 seconds and time = 20 seconds.

[0062] Figure 7 shows water droplet contact angle as a function of elapsed time for a variety of iron-starch compositions comprising different amounts of iron. The percent iron refers to the percent (wt / wt) of iron salt to total weight of the carrier used in preparation of the composition. 5(Fe) means that the composition was prepared using 5% (wt / wt) iron salt to total weight of the carrier, 10(Fe) means that the composition was prepared using 10% (wt / wt) iron salt to total weight of the carrier, 15(Fe) means that the composition was prepared using 15% (wt / wt) iron salt to total weight of the carrier, 25(Fe) means that the composition was prepared using 25% (wt / wt) iron salt to total weight of the carrier, 35(Fe) means that the composition was prepared using 35% (wt / wt) iron salt to total weight of the carrier, 45(Fe) means that the composition was prepared using 45% (wt / wt) iron salt to total weight of the carrier, and 55(Fe) means that the composition was prepared using 55% (wt / wt) iron salt to total weight of the carrier.

[0063] Figure 8 shows pictures of com seed germination from seeds coated with zinc-starch compositions as disclosed herein comprising various zinc concentrations, including 0.1 % (wt / wt) zinc based on the total weight of the composition and seed (a), 0.2% (wt / wt) zinc based on the total weight of the composition and seed (b), 0.3% (wt / wt) zinc based on the total weight of the composition and seed (c), 0.4% (wt / wt) zinc based on the total weight of the composition and seed (d), and 0.5% (wt / wt) zinc based on the total weight of the composition and seed (e), compared to a control being an uncoated seed (f).

[0064] Figure 9 shows boxplots of hypocotyl length, dry root weight and dry hypocotyl weight for corn plants grown from com seeds coated with zinc-starch compositions as disclosed herein comprising various zinc concentrations, including0.1% (wt / wt) zinc based on the total weight of the composition and seed (RX494 1 %),0.2% (wt / wt) zinc based on the total weight of the composition and seed (RX494 2%),0.3% (wt / wt) zinc based on the total weight of the composition and seed (RX494 3%),0.4% (wt / wt) zinc based on the total weight of the composition and seed (RX494 4%), and 0.5% (wt / wt) zinc based on the total weight of the composition and seed (RX494 5%), compared to a control being an uncoated seed (uncoated) and a control being treated with fungicides or pesticides (whole formula).

[0065] Figure 10 shows pictures of canola seed germination comparing untreated seeds (left-hand picture) to seeds coated with a manganese-starch composition as disclosed herein at a rate of 1.5 grams of manganese-starch composition for every kg of canola seed.

[0066] Figure 11 shows germination rate, seedling fresh weight, normal seedling weight and seedling dry weight as a function of different application rates of a manganese-starch composition as disclosed herein on canola seeds.

[0067] Figure 12 shows pictures of chickpea seed germination comparing untreated seeds (left-hand picture) to seeds coated with a zinc-starch composition as disclosed herein at a rate of 1 .5 grams of zinc-starch composition for every kg of chickpea seed.

[0068] Figure 13 shows germination rate, seedling fresh weight, normal seedling weight and seedling dry weight as a function of different application rates of a zinc- starch composition as disclosed herein on chickpea seeds.

[0069] Figure 14 shows pictures of lentil seed germination comparing untreated seeds (left-hand picture) to seeds coated with an iron-starch composition as disclosed herein at a rate of 0.25 grams of iron-starch composition for every kg of lentil seed.

[0070] Figure 15 shows germination rate, seedling fresh weight, normal seedling weight and seedling dry weight as a function of different application rates of an iron- starch composition as disclosed herein on lentil seeds.DETAILED DESCRIPTION

[0071] In the context of the present disclosure, various terms are used in accordance with what is understood to be the ordinary meaning of those terms.

[0072] In various embodiments, the disclosure provides compositions for providing nutrients to plants and for use as a coating. For example, the compositions may interact with the microbiome of soils in order to release nutrients to plants. The compositions comprise a carrier comprising starch; and an element, wherein the element is covalently bonded to the carrier, and wherein a water droplet contact angle of the composition is greater than a water droplet contact angle of starch under the same conditions and after the same elapsed time up to one hour. In various embodiments, the carrier is soluble or partially soluble in water. In various embodiments, the composition is insoluble in water. By having the water droplet contact angle of the composition greater than the water droplet contact angle of starch under the same conditions, the composition is more hydrophobic than starch, indicating that the composition is less soluble in water than starch, and therefore can be used to reduce the rate of dissolution of the element in soils. Furthermore, the hydrophobicity of the composition may be modified by increasing or decreasing the amount of element in the composition, depending on the application of the composition. For example, increasing the amount of element in the composition increases the hydrophobicity of the composition, while decreasing the amount of element in the composition decreases the hydrophobicity of the composition. Therefore, in various embodiments, if the composition is used as a coating, the composition may be “tuned” with respect to the compound or particle being coated in order to modify the hydrophobicity of the coated compound or particle. The compositions as disclosed herein can be used as a slow- or controlled-release coating for micro- and macro-nutrients for plants. The compositions comprise environmentally friendly materials which are non-toxic, non-hazardous and micro-plastic free, and are prepared by environmentally friendly processes. In addition to the element, the carrier may also provide additional plant nutrients to soil. Thus, the compositions as disclosed herein provide benefits to plant nutrition and adjust soil nutrient mobility. Furthermore, these coating products are biodegradable, with additional benefits to soil health through increased soil microbial growth.

[0073] The term “hydrophobic” refers to a property of a composition in which the composition repels water.

[0074] The term “hydrophilic” refers to a property of a composition in which the composition has an affinity for water.

[0075] The term “element” refers to a nutrient that sustains an organism in its existence, by promoting organism growth, replacing loss and / or providing energy. The element can be taken into the organism by any means that the organism uses to take in nutrients. For example, if the organism is a plant, it typically absorbs nutrients through its roots and leaves. The element may be a nutrient for plant growth. In various embodiments, the element may be a cation. In various embodiments, the element may be Mn, Fe, Co, Cu, Zn, B, Si, Ca, Mo or Mg or any isotope thereof. In various embodiments, the element is Fe2+, Fe3+, Mn2+, Ca2+, Cu+, Cu2+, Mg2+, Mo4+, Mo6+or Zn2+. In various embodiments, the element is Zn2+, Mn2+, Fe2+or Fe3+.

[0076] A salt of the element may be soluble or partially soluble in water. The term “partially soluble” may mean that 1 gram of elemental salt requires 100 mL to 1000 mL of water to dissolve.

[0077] In various embodiments, the element is in a biologically available form. The term “biologically available form” means that a micronutrient is present in an oxidation state that allows for transport across a cellular membrane without requiring a reduction or change in oxidation state prior to cross-membrane transport.

[0078] The term “biological demand” refers to an act of acquisition or interaction between an organism and the composition in which the element is acquired or sequestered from the composition and taken into cells through trans-membrane transport or into tissues of the organism.

[0079] A rate of release of the element from the carrier is governed by the level of biological demand around the composition. For example, a higher concentration of biological demand may result in a faster release of the element from the carrier than a lower concentration of biological demand. The higher concentration of biological demand may result from the number of microorganisms in a particular area. As the rate of release depends on biological demand, an area of high localized concentration of element does not form. Such an area of high localized concentration is undesirable as the element may be toxic to plants in high concentrations. Details of the mechanism ofthe release of the element from the composition and uptake by a plant is described in more detail below.

[0080] In various embodiments, the composition may comprise at least about 1 % (wt / wt) of the element, based on the total weight of the composition. In various embodiments, the composition may comprise at least about 2% (wt / wt) of the element, based on the total weight of the composition. In various embodiments, the composition may comprise at least about 4% (wt / wt) of the element, based on the total weight of the composition. In various embodiments, the composition may comprise at least about 5% (wt / wt) of the element, based on the total weight of the composition. In various embodiments, the composition may comprise at least about 6% (wt / wt) of the element, based on the total weight of the composition. In various embodiments, the composition may comprise at least about 8% (wt / wt) of the element, based on the total weight of the composition. In various embodiments, the composition may comprise at least about 10% (wt / wt) of the element, based on the total weight of the composition. In various embodiments, the composition may comprise between about 1 % and about 17% (wt / wt) of the element, based on the total weight of the composition, or any amount therebetween. In various embodiments, the composition may comprise between about 1 % (wt / wt) and about 5% (wt / wt) of the element, based on the total weight of the composition, or any amount therebetween.

[0081] In various embodiments, the carrier comprises starch. Starch is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. It consists of two types of molecules, the linear and helical amylose, and the branched amylopectin. It is a biopolymer composed of a-amylose and amylopectin and is produced by most green plants. For example, the carrier may comprise at least about 20% starch to total weight of the carrier. For example, the carrier may comprise at least about 30% starch to total weight of the carrier. For example, the carrier may comprise at least about 40% starch to total weight of the carrier. For example, the carrier may comprise at least about 50% starch to total weight of the carrier. For example, the carrier may comprise at least about 60% starch to total weight of the carrier. For example, the carrier may comprise at least about 70% starch to total weight of the carrier. In various embodiments, the polymeric carrier consists of starch. In variousembodiments, the carrier may comprise pea starch, lentil starch, oat starch, potato starch, sweet potato starch, com starch, bean starch, cassava starch, wheat starch, rice starch, sorghum starch, millet starch, taro starch, yam starch, arrow root starch, sago palm starch, plantains starch, banana starch, squash starch or any combination thereof. The term “fibre” refers to a component of plant material that is not soluble in water. The carrier may also be synthetically produced.

[0082] In various embodiments, the composition may have a moisture content of about 40% (wt / wt) or less, based on the total weight of the composition. For example, the composition may have a moisture content of about 30% (wt / wt) or less, based on the total weight of the composition. For example, the composition may have a moisture content of about 20% (wt / wt) or less, based on the total weight of the composition. For example, the composition may have a moisture content of about 10% (wt / wt) or less, based on the total weight of the composition.

[0083] The term “water droplet contact angle” refers to the angle where a liquidvapour interface meets a solid surface. The water droplet contact angle is formed when a drop of water is placed on a surface of the composition. The surface tension of the water and the attraction of the water to the surface causes the drop to form a dome, which may then flatten due to the properties of the water phase and the surface. The measured water droplet contact angle depends on the roughness of the surface on which the measurement is made, the temperature and pressure of the environment in which the measurement is made, and the atmosphere of the vapour phase. The water droplet contact angle may be used to measure hydrophobicity of the compositions as disclosed herein, by preparing a sample of the composition, and then adding a droplet of water to a surface thereof. Depending on the properties of the composition, a measure of the water droplet contact angle is indicative of the hydrophobic properties of the composition. For example, if the water drop contact angle is greater than 90°, then the composition may be classified as hydrophobic. In contrast, if the water droplet contact angle is less than 90°, then the composition may be classified as hydrophilic. For pure starch, which is a hydrophilic material, the water droplet contact angle is low, and within time, the initial dome that is formed “flattens out” on the surface, as shown,for example, in Figure 6. Thus, binding of the element to the starch is used to adjust the hydrophobicity of starch.

[0084] In various embodiments, the water droplet contact angle of the composition is greater than a water droplet contact angle of starch under the same conditions and after the same elapsed time up to one hour. “Same conditions” include the same vapour atmosphere, and environmental temperature and pressure for the measurements. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 2 seconds. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 5 seconds. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 10 seconds. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 1 minute. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 2 minutes. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions after the same elapsed time up to 5 minutes. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 10 minutes. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions after the same elapsed time up to 1600 seconds. In various embodiments, the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions after the same elapsed time up to 3960 seconds. In various embodiments, the water droplet contact angle of the composition is at least 20° greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 1600 seconds. In variousembodiments, the water droplet contact angle of the composition is at least 20° greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 3960 seconds. In various embodiments, the water droplet contact angle of the composition is at least 20° greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to one hour. In various embodiments, the water droplet contact angle of the composition is at least 20° greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time longer than one hour. In various embodiments, the water droplet contact angle of the composition is at least 60° greater than the water droplet contact angle of starch under the same conditions and after the same elapsed time up to 10 seconds. In various embodiments, the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 10 seconds, compared to starch, which has a contact angle of less than 20° at the elapsed time of 10 seconds and under the same conditions. In various embodiments, the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions. In various embodiments, the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 1600 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 1600 seconds and under the same conditions. In various embodiments, the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 3960 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 3960 seconds and under the same conditions. In various embodiments, the water droplet contact angle of the composition is greater than 90° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions. In various embodiments, the water droplet contact angle of the composition is greater than 20° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions. In various embodiments, the water droplet contact angle of the composition is greater than 20° at an elapsed time of onehour, compared to starch, which has a contact angle of 0° at the elapsed time of one hour and under the same conditions.

[0085] The compositions disclosed herein are prepared by mixing a base in a solvent to form a mixture; spraying the mixture on a carrier comprising starch and mixing to form a starch mixture; mixing a salt or an ionic salt of an element to form an element mixture; spraying water on the element mixture to form a product mixture; and stirring, heating and drying the product mixture to a moisture content of about 40% (wt / wt) or less to form the composition. By using the foregoing method, the starch is partially hydrolysed, thereby improving the reactivity of the starch.

[0086] In various embodiments, the heating is conducted at room temperature. In various embodiments, the heating is conducted between about 20°C and about 80°C, or at any temperature therebetween. For example, the heating may be conducted between about 20°C and about 60°C, or at any temperature therebetween.

[0087] In various embodiments, an amount of the base in the mixture is about 1 .0 g / mL to about 1 .5 g / mL, or any amount therebetween.

[0088] In various embodiments, an amount of the salt or the ionic salt of the element in the element mixture is about 0.3 g / mL to about 0.7 g / mL, or any amount therebetween.

[0089] In various embodiments, the solvent may be water, methanol, ethanol, propanol, acetone, ethyl acetate, acetonitrile, or any combination thereof. For example, the solvent may be water.

[0090] In various embodiments, the base is potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydroxide, ammonium hydroxide, or a combination thereof. For example, the base may be potassium hydroxide. In various embodiments, the hydroxide groups may also be deprotonated by an electrochemical surface activation method.

[0091] In various embodiments, the salt or the ionic salt of the element is ZnSO4, Fe2Os, CuSCM, MnSCM, ZnCL, FeCh, MnCL, FeSO4, CuCL, MnCL, ZnO, ZnCOs, MgSCM, MgCL, FeCOs, Fe2(CO3)3, MnCOs, Zn(PO4)2, Mn3(PO4)2 or a combination thereof. For example, the base may be ZnSO4. For example, the base may be Fe2Os. For example, the base may be CuSCM. For example, the base may be MnSCM.

[0092] In various embodiments, about 10% to about 25% (wt / wt) base to total weight of the carrier, or any amount therebetween, is used in the method.

[0093] In various embodiments, about 25% to about 50% (wt / wt) base to total weight of the salt or the ionic salt of the element, or any amount therebetween, is used in the method. For example, about 30% to about 45% (wt / wt) base to total weight of the salt or the ionic salt of the element is used in the method.

[0094] In various embodiments, about 5% to about 55% (wt / wt) salt or ionic salt of the element to total weight of the carrier, or any amount therebetween, is used in the method.

[0095] In various embodiments, the bonding between the carrier and the element comprises element-starch bonding. In various embodiments, the bonding between the carrier and the element comprises chemical bonding. In various embodiments, the chemical bonding comprises element-hydroxide covalent bonding. In various embodiments, the element may form an aggregate of elements. In various embodiments, the aggregate comprises element-element covalent bonding.

[0096] In various embodiments, the composition is resistant to element leaching in water. In various embodiments, the carrier composition may minimize or decrease element leaching into water sources.

[0097] In various embodiments, the composition may be non-toxic. For example, the composition does not cause nutrient toxicity when deployed in high concentrations. The compositions may be non-toxic to plants, humans and animals.

[0098] In various embodiments, the composition may be added to an environment of a plant in order to increase growth of the plant. The environment may be an agricultural field or soil. In various embodiments, the composition may be applied to soil. Without wishing to be bound by theory, the microbiome in soil may consume the starch present in the composition, thereby releasing the element into the soil in bioavailable form for uptake by a plant. More specifically, the presence of the composition in the soil results in an increase of microbial biomass due to the biologically available carbon source in the composition, i.e. the starch. As the carbon is consumed, the microbial community releases the nutrients back into the soil in bioavailable form ready for plant uptake.

[0099] Alternatively, the compositions as described herein may be used as a coating, in order to modify the hydrophobicity of the coated particle or compound, to aid in its delivery to a target or target environment. Such coatings do not contain any microplastics and therefore, do not contribute to microplastics pollution; nor do the coatings have toxicity to plants. For example, the compositions as described herein may be used as a coating for a seed. When the seed is planted in soil, the microbiome in soil consume the starch, thereby releasing the element in bioavailable form. The presence of the element may aid in seed germination and growth. The compositions as described herein may also be used as a coating for a fertilizer particle, as a means of adjusting the hydrophobicity of the fertilizer particle to improve its effectiveness in soil. For example, for a water soluble fertilizer particle, it may be coated with a composition as described herein which increases the hydrophobicity of the coated particle, thereby decreasing the rate of dissolution of the fertilizer particle in water and decreasing the amount of fertilizer washing away in the soil. Alternatively, for a water insoluble fertilizer particle, it may be coated with a composition as described herein which decreases the hydrophobicity of the coated particle, thereby increasing the availability of the fertilizer in soil. The coatings as described herein may also have applications in additional industries, such as in the pharmaceutical industry.EXAMPLES

[0100] These examples illustrate various aspects of the invention, evidencing a variety of conditions for preparing compositions comprising a carrier comprising starch; and an element, wherein the element is covalently bonded to the carrier and wherein a water droplet contact angle of the composition is greater than a water droplet contact angle of starch under the same conditions and after the same elapsed time up to one hour. Selected examples are illustrative of advantages that may be obtained compared to alternative methods, and these advantages are accordingly illustrative of particular embodiments and not necessarily indicative of the characteristics of all aspects of the invention.

[0101] As used herein, the term “about” refers to an approximately + / -10% variation from a given value. It is to be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.Example 1 : Preparation of a zinc-starch composition

[0102] 25 grams of KOH was combined with 20.4 mL of water until dissolved.The solution was sprayed on 100 g of pea starch to form a pea starch mixture and the mixture was stirred for 30 minutes. Next, 55 grams of zinc sulfate was mixed with 82.5 mL of water until the zinc sulfate was dissolved. The solution was sprayed on the pea starch mixture and stirred for 30 minutes. The mixture was heated to 55°C and stirred for a period of 60 minutes. The resulting composition was then dried to less than 10% moisture content at which point the synthesis was considered complete. Figue 1 shows a SEM-EDS image of the zinc-starch composition. The particles in the spectrum show zinc-starch covalent bonding (such as zinc-hydroxide covalent bonding), as indicated by the presence of K2SO4 salt products on the surface of the particles. Zinc may bond to a single starch molecule or cross-link between more than one starch molecule.

[0103] Properties of the zinc-starch composition are shown in Table 1. In the context of these Examples, leaching refers to the extent to which the element dissolved in water when the composition was placed in neutral water. For example, the composition was immersed in fresh water at room temperature to determine if the element, in this case zinc, would dissolve in water. The pH of the water was also measured. The method used to determine zinc leaching was the Marczenko method (Z. Marczenko & M. Balcerzak, “Separation, Preconcentration, and Spectrophotometry in Inorganic Analysis”, Chapter 26-2-2-1 , 10-phenanthroline method (pages 228-230)” Elsevier, Oct. 18, 2000). The composition was also tested for zinc loading by elemental analysis. Analysis was undertaken with a CHN Analyzer. The CHN analysis provided the percent by weight of C, H, N and O in the composition. The difference between this percent by weight and the total weight of the sample was the amount of zinc present, as there were no other elements present in the compositions.Table 1. Properties of zinc-starch composition prepared according to Example 1Example 2: Preparation of an iron-starch composition

[0104] 12.7 grams of KOH was combined with 10 mL of water until dissolved.The solution was sprayed on 100 g of pea starch to form a pea starch mixture and the mixture was stirred for 35 minutes. Next, 35 grams of iron sulfate was mixed with 70 mL of water until the iron sulfate was dissolved. The solution was sprayed on the pea starch mixture and stirred for 30 minutes. The mixture was heated to 40°C and stirred for a period of 30 minutes. The resulting composition was then dried to less than 10% moisture content at which point the synthesis was considered complete. Figue 2 shows SEM-EDS images of the iron-starch composition.

[0105] Table 2 provides a summary of properties of the iron-starch composition. All measurements were made as described above in Example 1 .Table 2. Properties of iron-starch composition prepared according to Example 2Example 3: Preparation of a copper-starch composition

[0106] 10 grams of KOH was combined with 8 mL of water until dissolved. The solution was sprayed on 100 g of pea starch and the mixture was stirred for 40 minutes. Next, 30 grams of copper sulfate was mixed with 75 mL of water until the copper sulfate was dissolved. The solution was sprayed on the pea starch mixture and stirred for 60 minutes. The mixture was then heated to 60°C and stirred for 60 minutes. The mixture was then dried to less than 10% moisture content at which point the synthesis was considered complete. Figue 3 shows SEM-EDS images of the copper-starch composition.

[0107] Table 3 provides a summary of properties of the copper-starch composition. All measurements were made as described above in Example 1 .Table 3. Properties of copper-starch composition prepared according to Example 3Example 4: Preparation of a manganese-starch composition

[0108] 10 grams of KOH was combined with 8 mL of water until dissolved. The solution was sprayed on 100 g of pea starch and the mixture was stirred for 40 minutes. Next, 30 grams of manganese sulfate was mixed with 75 mL of water until the manganese sulfate was dissolved. The solution was sprayed on the pea starch mixture and stirred for 60 minutes. The mixture was heated to 60°C and stirred for 60 minutes. The mixture was then dried to less than 10% moisture content at which point the synthesis was considered complete. Figue 4 shows SEM-EDS images of the manganese-starch composition.

[0109] Table 4 provides a summary of properties of the manganese-starch composition. All measurements were made as described above in Example 1.Table 4. Properties of manganese-starch composition prepared according to Example 2Example 5: Hydrophobicity of starch compositions

[0110] A series of water droplet contact angle measurements were made for the compositions prepared in Examples 1-4. Samples of each of the compositions of Examples 1-4 were pressed in a holder with dimensions of 3 cm diameter, or pelleted at the same size. The packed, smooth and flat surface was then used for these measurements. A drop of water was added to each sample at time = 0 seconds. A video of the droplet was recorded from time = 0 seconds to time = 1600 seconds. At various time intervals, a freeze-frame was isolated and the contact angle was measured. Untreated starch was also tested as a control and prepared as the same pressed composition or pellet.

[0111] Figure 5 shows a comparison between the contact angle of untreated starch at time = 0 seconds and an iron-starch composition as disclosed herein. The untreated starch has a contact angle of 50° and is considered hydrophilic. The ironstarch composition has a contact angle of 140° and is considered hydrophobic.

[0112] Figure 6 shows a water droplet contact angle comparison between untreated starch and the compositions prepared according to Examples 1-4 at elapsed times of time = 0 seconds, time = 1 second, time = 10 seconds and time = 20 seconds. As can be seen, all of the compositions of Examples 1-4 are more hydrophobic than untreated starch.

[0113] Studies were also carried out to evaluate the difference in water droplet contact angle between compositions comprising different amounts of element, in this Example, iron. Figure 7 the water droplet contact angle as a function of elapsed time for a variety of iron-starch compositions comprising different amounts of iron. The percent iron refers to the percent (wt / wt) of iron salt to total weight of the carrier used in preparation of the composition. For example, 5(Fe) means that the composition was prepared using 5% (wt / wt) iron salt to total weight of the carrier, 10(Fe) means that the composition was prepared using 10% (wt / wt) iron salt to total weight of the carrier, 15(Fe) means that the composition was prepared using 15% (wt / wt) iron salt to total weight of the carrier, 25(Fe) means that the composition was prepared using 25% (wt / wt) iron salt to total weight of the carrier, 35(Fe) means that the composition was prepared using 35% (wt / wt) iron salt to total weight of the carrier, 45(Fe) means that the composition was prepared using 45% (wt / wt) iron salt to total weight of the carrier, and 55(Fe) means that the composition was prepared using 55% (wt / wt) iron salt to total weight of the carrier. Generally speaking, increasing the amount of iron in the composition corresponded to increased hydrophobicity, and lower loadings of iron corresponded to lower hydrophobicity.Example 6: Com seed germination

[0114] This experiment was carried out in a growth chamber to evaluate the effect of various zinc-starch compositions on the germination rate of corn seeds. The seeds were coated with a zinc-starch composition comprising various zincconcentrations, including 1 % (wt / wt) zinc based on the total weight of the composition, 2% (wt / wt) zinc based on the total weight of the composition, 3% (wt / wt) zinc based on the total weight of the composition, 4% (wt / wt) zinc based on the total weight of the composition, and 5% (wt / wt) zinc based on the total weight of the composition. When the coated seeds were prepared, the coated seeds comprised 0.1 % (wt / wt) zinc based on the total weight of the composition and seed (RX494 1%), 0.2% (wt / wt) zinc based on the total weight of the composition and seed (RX494 2%), 0.3% (wt / wt) zinc based on the total weight of the composition and seed (RX494 3%), 0.4% (wt / wt) zinc based on the total weight of the composition and seed (RX494 4%), and 0.5% (wt / wt) zinc based on the total weight of the composition and seed (RX494 5%). The treatments were set in complete randomized design having 5 replications with two sets of control (raw seed as a first control (referred to as “uncoated seed” in Figure 8 and “uncoated” in Figure 9) and seed with treatment such as fungicides or pesticides (referred to as “whole formula” in Figure 9)) and 10 subsamples for a total of 350 seeds (7 treatments x 5 replicates x 10 subsamples). Seed subsamples (10 seeds) were placed in petri discloses (15 cm diameter) on one layer of Whatman filter paper and kept at 22°C, 50% humidity and 16 / 8 light / dark. The seeds were moistened with water as needed. The germination rate, root weight, hypocotyl length and hypocotyl weight were recorded after 7 days.

[0115] Pictures of com seed germination are shown in Figure 8. As can be seen from Figure 8, all of the seeds coated with the zinc-starch composition displayed increased germination, with the seeds coated with 5% (wt / wt) zinc showing the most germination. Coating the seeds with the compositions as disclosed herein was shown to increase the efficacy of corn seed germination.

[0116] Figure 9 shows a boxplot of hypocotyl length, dry root weight and dry hypocotyl weight for each of the five different zinc-starch compositions compared to the two controls. “RX494” indicates a zinc-starch composition comprising the labeled amount of zinc as % (wt / wt) based on the total weight of the composition. Growth of the plants was improved by coating the seeds with the compositions as indicated by the median value of dry root and dry hypocotyl as compared to untreated control, showingthat the zinc-starch compositions as disclosed herein are effective at improving seed germination.Example 7: Seed germination

[0117] This experiment was carried out in a growth chamber to evaluate the effect of application rate of the various compositions as disclosed herein on the germination of various seeds. Different application rates of the composition onto the seeds were tested, and compared to seeds that were not coated with the composition (referred to as “UTC” or untreated control in Figures 11 , 13 and 15).

[0118] Pictures of canola seed germination are shown in Figure 10. As can be seen from Figure 10, and comparing the left-hand picture (untreated) with the right-hand picture (treated), all of the seeds coated with a manganese-starch composition at a rate of 1.5 grams of manganese-starch composition for every kg of canola seed showed increased germination. Figure 11 shows the germination rate, seedling fresh weight, normal seedling weight and seedling dry weight as a function of application rate of manganese-starch composition on canola seeds.

[0119] Pictures of chickpea seed germination are shown in Figure 12. As can be seen from Figure 12, and comparing the left-hand picture (untreated) with the right-hand picture (treated), all of the seeds coated with a zinc-starch composition at a rate of 1 .5 grams of zinc-starch composition for every kg of chickpea seed showed increased germination. Figure 13 shows the germination rate, seedling fresh weight, normal seedling weight and seedling dry weight as a function of application rate of the zinc- starch composition on chickpea seeds.

[0120] Pictures of lentil seed germination are shown in Figure 14. As can be seen from Figure 14, and comparing the left-hand picture (untreated) with the right-hand picture (treated), all of the seeds coated with an iron-starch composition at a rate of 0.25 grams of iron-starch composition for every kg of lentil seed showed increased germination. Figure 15 shows the germination rate, seedling fresh weight, normal seedling weight and seedling dry weight as a function of application rate of the iron- starch composition on lentil seeds.

[0121] Although various embodiments of the invention are disclosed herein, many adaptations and modifications may be made within the scope of the invention in accordance with the common general knowledge of those skilled in this art. Such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way. Numeric ranges are inclusive of the numbers defining the range. The word "comprising" is used herein as an open-ended term, substantially equivalent to the phrase "including, but not limited to", and the word "comprises" has a corresponding meaning. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a thing" includes more than one such thing. Citation of references herein is not an admission that such references are prior art to the present invention. Any priority document(s) and all publications, including but not limited to patents and patent applications, cited in this specification are incorporated herein by reference as if each individual publication were specifically and individually indicated to be incorporated by reference herein and as though fully set forth herein. The invention includes all embodiments and variations substantially as hereinbefore described and with reference to the examples and drawings.

Claims

AMENDED CLAIMS received by the International Bureau on 16 October 2024 (16.10.2024)

1. A composition comprising: a carrier comprising starch; and an element, wherein the element is covalently bonded to the carrier, and wherein a water droplet contact angle of the composition is greater than a water droplet contact angle of starch under the same conditions and after the same elapsed time up to one hour.

2. The composition of claim 1 , wherein the element is a cation.

3. The composition of claim 1 or 2, wherein the element is Fe2+,Fe3+, Mn2+, Cu+, Cu2+, Ca2+, Mg2+, Mo4+, Mo6+or Zn2+.

4. The composition of any one of claims 1 to 3, wherein the carrier comprises at least 60% starch.

5. The composition of any one of claims 1 to 4, wherein the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 100 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 100 seconds and under the same conditions.

6. The composition of any one of claims 1 to 4, wherein the water droplet contact angle of the composition is between 70° and 160° at an elapsed time of 3960 seconds, compared to starch, which has a contact angle of 0° at the elapsed time of 3960 seconds and under the same conditions.

7. The composition of any one of claims 1 to 4, wherein the water droplet contact angle of the composition is greater than 20° at an elapsed time of one hour, compared to starch, which has a contact angle of 0° at the elapsed time of one hour and under the same conditions.

8. The composition of any one of claims 1 to 4, wherein the water droplet contact angle of the composition is greater than the water droplet contact angle of starch under the same conditions and at an elapsed time of 3960 seconds.

9. The composition of any one of claims 1 to 4, wherein the water droplet contact angle of the composition is at least 60° greaterAMENDED SHEET (ARTICLE 19)than the water droplet contact angle of starch under the same conditions and at an elapsed time of 10 seconds.

10. The composition of any one of claims 1 to 9, wherein the composition comprises at least about 5% (wt / wt) of the element, based on the total weight of the composition.

11. The composition of any one of claims 1 to 10, wherein the carrier is pea starch, lentil starch, oat starch, potato starch, sweet potato starch, corn starch, bean starch, cassava starch, wheat starch, rice starch, sorghum starch, millet starch, taro starch, yam starch, arrow root starch, sago palm starch, plantains starch, banana starch, squash starch or a combination thereof.

12. A method for preparing a composition as defined in any one of claims 1 to 11 , the method comprising: mixing a base in a first solvent to form a mixture; spraying the mixture on a carrier comprising starch and mixing to form a starch mixture; adding a salt or an ionic salt of an element to form an element mixture; spraying water on the element mixture to form a product mixture; and stirring, heating and drying the product mixture to a moisture content of about 40% (wt / wt) or less to form the composition.

13. The method of claim 12, wherein the heating is conducted between about 20°C and about 60°C.

14. The method of claim 12 or 13, wherein an amount of the salt or the ionic salt of the element in the element mixture is about 0.3 g / mL to about 0.7 g / mL.

15. The method of any one of claims 12 to 14, wherein the solvent is water.

16. The method of any one of claims 12 to 15, wherein the base is potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydroxide, ammonium hydroxide or a combination thereof.

17. The method of any one of claims 12 to 16, wherein the salt or the ionic salt of the element is ZnSO4, Fe2O3, CuSO4, MnSO4, ZnCI2, FeCI3, MnCI2, FeSO4, CuCI2, MnCI2, ZnO,AMENDED SHEET (ARTICLE 19)ZnCO3, MgSO4, MgCI2, FeCO3, Fe2(CO3)3, MnCO3, Zn(PO4)2, Mn3(PO4)2or a combination thereof.

18. The method of any one of claims 12 to 17, wherein about 10% to about 25% (w / w) base to total weight of the carrier is used.

19. The method of any one of claims 12 to 18, wherein about 5% to about 55% (wt / wt) salt or ionic salt of the element to total weight of the carrier is used.

20. A seed or a fertilizer particle coated with a composition as defined in any one of claims 1 to 11 .AMENDED SHEET (ARTICLE 19)

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