Nanostructured agrochemical delivery carriers

Abstract

Aspects of the present disclosure relate to nanostructured agrochemical delivery carriers. The carrier has a core-shell structure. The core comprises a first polymeric material. The shell at least partially wraps the core. The shell comprises a second polymeric material. The core, the shell, or both comprise an agrochemical component distributed around the first polymeric material, the second polymeric material, or both. Release of an agrochemical component from the core, the shell, or both is triggered by exposure to at least one of a predetermined enzyme, a predetermined pH, a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63 / 318,972, filed on March 11, 2022, entitled “NANOSTRUCTURED AGRICHEMICALDELIVERY CARRIER,” the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0003] The delivery of nutrients helps to make the plants grow easily. The delivery of nutrients may be slightly inefficient. For example, a particular nutrient may not be delivered at the right time, location and / or in the right dosage. Summary of the invention

[0004] The present disclosure addresses, among other things, the inefficient delivery of nutrients and other substances to plants.

[0005] Aspects of the present disclosure relate to nanostructured agricultural chemical delivery carriers. The carrier has a core-shell structure. The core comprises a first polymer material. The shell at least partially encapsulates the core. The shell comprises a second polymer material. The core, the shell, or both comprise an agricultural chemical component distributed around the first polymer material, the second polymer material, or both. The release of the agricultural chemical component from the core, the shell, or both is triggered by exposure to at least one of: a predetermined enzyme, a predetermined pH, a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source.

[0006] Aspects of the present disclosure relate to methods for preparing nanostructured agricultural chemical delivery carriers. The carrier has a core-shell structure. The core comprises a first polymer material. The shell at least partially encapsulates the core. The shell comprises a second polymer material. The core, the shell, or both comprise an agricultural chemical component distributed around the first polymer material, the second polymer material, or both. The release of the agricultural chemical component from the core, the shell, or both is triggered by exposure to at least one of the following: a predetermined enzyme, a predetermined pH, a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source. The method includes setting a liquid core precursor composition in a first chamber of a coaxial dispenser. The liquid core precursor composition comprises the first polymer material and optionally comprises the agricultural chemical component. The method also includes setting a liquid shell precursor in a second chamber of the coaxial dispenser, the liquid shell precursor composition comprising the second polymer material and optionally comprising the agricultural chemical component. The method also includes applying a voltage to the coaxial dispenser. The method also includes applying a voltage to a substrate in flow communication with the coaxial dispenser. The method also includes flowing the liquid core precursor composition from the first chamber to the substrate. The method also includes flowing the shell precursor composition from the second chamber to the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The drawings generally illustrate various embodiments of the invention by way of example and not by way of limitation.

[0008] Figures 1A to 1C Schematic diagram of the study design illustrating (1A) the concept of core-shell nanostructures and pH and enzyme stimulus responsive agricultural chemical release, (1B) the synthesis of pH and enzyme responsive core-shell nanostructures using electrospray, and (1C) plant growth studies using pH and enzyme responsive core-shell nanostructures.

[0009] Figures 2A to 2C are photographs and graphs showing the morphology and size distribution of different types of core-shell nanostructures. Figure 2A shows a type I nanostructure, Figure 2B shows a type II nanostructure, and Figure 2C A type III nanostructure is shown.

[0010] Figures 3A to 3E Images showing the core-shell structure and elemental mapping of copper (3B), sulfur (3C), phosphorus (3D), and potassium (3E).

[0011] Figures 4A to 4D The release kinetics of copper under different pH and enzyme conditions are shown. Figure 2A and 2B Type I and type II nanostructures under different pH conditions are shown. Figure 2C and 2D show type I and type II nanostructures in the presence or absence of different enzymes.

[0012] Figures 5A to 5D is a picture showing the photosynthesis spectrum of soybean and wheat. Figure 5A Relative chlorophyll levels in soybeans are shown. Figure 5B The PS1 active site in soybean is shown. Figure 5C PhiNO levels in wheat are shown. Figure 5D LEF in wheat is shown. Error bars correspond to sem (n=5). Values ​​shown with different letters are significantly different at p≤0.05 (one-way ANOVA with Tukey post hoc test).

[0013] Fig. 6A and 6B The element contents in soybean are shown. Fig. 6A The zinc content in soybean leaves is shown. Figure 6B Sodium content in soybean leaves is shown. Values ​​shown with different letters are significantly different at p≤0.05 (one-way ANOVA with Tukey post hoc test). DETAILED DESCRIPTION

[0014] Reference will now be made in detail to certain embodiments of the disclosed subject matter, examples of which are partially illustrated in the accompanying drawings.While the disclosed subject matter will be described in conjunction with the recited claims, it will be understood that the illustrated subject matter is not intended to limit the claims to the disclosed subject matter.

[0015] Inefficient delivery of agricultural chemicals (fertilizers and pesticides) in agricultural food systems (e.g., crops, livestock, forestry, aquaculture, and fisheries) is associated with serious negative global health and public health impacts. According to some estimates, 60% to 90% of applied fertilizers and pesticides are lost due to evaporation, degradation, and environmental runoff. This inefficiency is mostly caused by the inability to deliver the active ingredient to the appropriate location (target) at the appropriate time and appropriate dosage. The Food and Agriculture Organization of the United Nations estimates that by 2050, food production will need to increase by 70% to 100% to maintain current population growth. Considering the negative pressures brought about by the increase in environmental pressures associated with changing climate and the net loss of arable soil, it becomes more challenging to reach this productivity level. Therefore, it is necessary to develop effective, targeted and precise agricultural chemical delivery technologies.

[0016] Precision agriculture is lacking. For example, the release of agricultural chemicals occurs mainly through passive diffusion, capsule erosion, or osmotic pressure, resulting in poor control and high inefficiency of agricultural chemical delivery. The present disclosure solves this shortcoming by developing a biological and environmental stimulus responsive nanostructured agricultural chemical delivery carrier platform for targeted and precise delivery to enhance the development of crops under both healthy conditions and pathogen infection conditions. In addition, these nanostructured agricultural chemical delivery carriers can use biodegradable, non-toxic materials and green synthesis steps consistent with sustainable agricultural principles.

[0017] According to a number of examples, the nanostructured agricultural chemical delivery carrier that can achieve the above benefits has a core-shell structure. The core-shell structure includes a core and also includes a shell that at least partially encapsulates the core. For example, the shell can encapsulate: about 80% to about 100% of the total surface area of ​​the core; about 90% to about 95% of the total surface area of ​​the core; less than, equal to, or more than about 80% of the total surface area of ​​the core, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or about 100% of the total surface area of ​​the core.

[0018] The core comprises a first polymer material and the shell comprises a second polymer material. The respective polymer materials provide the structure of the core and the shell. They also constitute the main components of the core and the shell. The core has an agricultural chemical component distributed around it. The shell may have an agricultural chemical component distributed around it, but in some instances, the shell may not contain an agricultural chemical component. As further described herein, the release of the agricultural chemical component from the core, the shell or both is triggered by exposure to at least one of the following: a predetermined enzyme, a predetermined pH, a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source. As further described herein, the release can be controlled to substantially conform to the desired release profile.

[0019] Nanostructured agricultural chemical delivery carriers are "nanoscale" carriers. For example, the average diameter of the nanostructured agricultural chemical delivery carrier is about 150nm to about 300nm, about 160nm to about 170nm, less than, equal to, or greater than about 150nm, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or about 300nm. The shell may have a thickness of about 10 nm to about 50 nm, about 10 nm to about 30 nm, less than, equal to, or greater than about 10 nm, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 nm.

[0020] The shell and the core can account for different amounts of the nanostructured agricultural chemical delivery vehicle. For example, the shell can be about 45% to about 62% by weight of the nanostructured agricultural chemical delivery vehicle; about 47% to about 60% by weight of the nanostructured agricultural chemical delivery vehicle; less than, equal to, or greater than about 45% by weight of the nanostructured agricultural chemical delivery vehicle, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or about 60% by weight of the nanostructured agricultural chemical delivery vehicle. The core can be about 38% to about 55% by weight of the nanostructured agricultural chemical delivery vehicle; about 40% to about 53% by weight of the nanostructured agricultural chemical delivery vehicle; less than, equal to, or greater than about 38% by weight of the nanostructured agricultural chemical delivery vehicle, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, or about 60% by weight of the nanostructured agricultural chemical delivery vehicle.

[0021] The specific surface area of ​​the nanostructured agricultural chemical delivery vehicle can be about 10 m 2 / g to about 30m 2 / g, about 13m 2 / g to about 20m 2 / g, less than, equal to, or greater than about 10m 2 / g, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or about 30m 2 / g. The surface area can affect the release profile of agricultural chemical components.

[0022] The first and second polymeric materials may comprise a single polymer or a mixture of polymers. Suitable polymers are those that are capable of degrading or releasing agricultural chemical components when in contact with any external triggering component described herein. Some examples of suitable polymers of the first and second polymeric materials include biopolymers based on polysaccharides. As understood, polysaccharides refer to carbohydrates (e.g., starch, cellulose, or glycogen) whose molecules contain a large number of sugar molecules bonded together. As further understood, biopolymers are natural polymers produced by cells of living organisms. Polysaccharides may account for: 50% to 100% by weight of polysaccharide-based biopolymers, 70% to 100% by weight of polysaccharide-based biopolymers, less than, equal to, or greater than about 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, 95% by weight, or about 100% by weight of polysaccharide-based biopolymers. A portion of a non-polysaccharide-based biopolymer may include any suitable portion or repeating unit of a non-sugar.

[0023] The first polymer material and the second polymer material can be the same (e.g., comprising the same polymer or a mixture of polymers) or the first polymer material and the second polymer material can be different. In some examples, the first polymer material and the second polymer material can comprise a mixture of the same polymer, but the amount of a single polymer can be different in each mixture.

[0024] Some examples of polysaccharide-based polymers of the first polymeric material, the second polymeric material, or both may include cellulose acetate, chitosan, zein, corn starch, polycaprolactone, or mixtures thereof. As understood, cellulose acetate refers to any acetate of cellulose. As an example, cellulose may contain 39.8% by weight acetyl. As understood, chitosan refers to a linear polysaccharide containing randomly distributed β-(1→4)-linked D-glucosamine (deacetylated units) and N-acetyl-D-glucosamine (acetylated units). As understood, zein is a class of prolamin proteins present in maize (maize) (corn), which is typically made into powder from corn gluten meal. As understood, corn starch is obtained from the endosperm of corn kernels and is a common food ingredient, typically used to thicken sauces or soups, and to prepare corn syrup and other sugars, and may be food grade or pharmaceutical grade. As will be appreciated, polycaprolactone is a biodegradable polyester having a low melting point of about 60° C. and a glass transition temperature of about −60° C. The polycaprolactone may have a weight average molecular weight of about 60,000 to about 100,000 or 75,000 to 85,000.

[0025] In one example, the first polymer material comprises a mixture of cellulose acetate, chitosan, zein, corn starch, and polycaprolactone. The mixture allows for the regulation of the release of the agricultural chemical component. The regulation can be achieved by controlling the amount of each polymer present in the first polymer material. As an example, cellulose acetate can be about 30% to about 50% by weight of the first polymer material; chitosan can be about 20% to about 40% by weight of the first polymer material; zein can be about 5% to about 20% by weight of the first polymer material; corn starch can be about 5% to about 20% by weight of the first polymer material; and polycaprolactone can be about 5% to about 20% by weight of the first polymer material. In other examples, cellulose acetate can be about 35% to about 45% by weight of the first polymer material; chitosan can be about 25% to about 35% by weight of the first polymer material; zein can be about 10% to about 15% by weight of the first polymer material; corn starch can be about 10% to about 15% by weight of the first polymer material; and polycaprolactone can be about 10% to about 15% by weight of the first polymer material.

[0026] The content of the second polymeric material may be different relative to the first polymeric material. Making the content of the first polymeric material and the second polymeric material different can help provide different release rates of the agricultural chemical component. As an example, the second polymeric material comprises cellulose acetate, chitosan, polycaprolactone, or a mixture thereof. In another example, the second polymeric material comprises cellulose acetate, chitosan and polycaprolactone. Similar to the first polymeric material, adjusting the mixture allows the release of the agricultural chemical component to be adjusted. The adjustment can be achieved by controlling the amount of each polymer present in the second polymeric material. As an example of adjustment, the composition of each polymer composition can be adjusted so that the core or shell is more hydrophilic or less hydrophilic. If the core or shell is more hydrophilic, it will degrade faster when exposed to moisture. As an example of a formulation, cellulose acetate can be about 20% to about 30% by weight of the second polymeric material; chitosan can be about 20% to about 30% by weight of the second polymeric material; and polycaprolactone can be about 40% to about 60% by weight of the second polymeric material. In other examples, cellulose acetate can be about 23% to about 28% by weight of the second polymeric material; chitosan can be about 23% to about 28% by weight of the second polymeric material; and polycaprolactone can be about 44% to about 56% by weight of the second polymeric material.

[0027] The agricultural chemical component present in the core (optional shell or both core and shell) can include micronutrients, macronutrients, pesticides, fungicides or their mixtures. Micronutrients are understood to refer to trace chemical elements or substances required for normal growth and development of living organisms. Some examples of micronutrients that can exist include copper, boron, zinc, manganese, iron, molybdenum, chlorine or their mixtures. The micronutrients mentioned here can be elemental forms or ionic forms (for example, the cations of salts). For example, copper can be used as CuSO4. The counterions of cations can include sulfates, sulfites, nitrates, nitrites, ammonia, hydroxides, etc.

[0028] Macronutrients are understood to refer to chemical elements or substances that are required for the normal growth and development of living organisms and that are larger than micronutrients. Some examples of macronutrients may include nitrogen, phosphorus, potassium or a mixture thereof. Nitrogen, phosphorus and potassium are sometimes referred to as "primary macronutrients". In some instances, agricultural chemicals components may include "minor macronutrients", which are also necessary, but consume less amount than primary macronutrients. Some examples of minor macronutrients include calcium, magnesium and sulphur. Like micronutrients, macronutrients may exist in elemental form or as a part of an ion pair.

[0029] The agricultural chemical component may also include other components such as pesticides or fungicides. Some examples of pesticides include organophosphates, pyrethroids, carbamates, and mixtures thereof. Some examples of fungicides include captan, organomercury, thiram, zineb, maneb, chlorneb, copper hydroxide, copper oxychloride, pentachloronitrobenzene, fludioxonil, carboxin, or mixtures thereof.

[0030] The agricultural chemical component can be distributed around the agricultural chemical delivery vehicle of the nanostructure in a variety of ways. For example, the agricultural chemical component may be present in both the shell and the core. In some examples where the agricultural chemical component is present in both the shell and the core, an equal portion (e.g., the total weight % of the agricultural chemical component in the agricultural chemical delivery vehicle of the nanostructure) of the agricultural chemical component may be in the shell and the core. Alternatively, a major portion (e.g., greater than 50 weight % of the total amount of the agricultural chemical component) may be located in the shell or the core. In the shell or the core, the agricultural chemical component may be evenly distributed or unevenly distributed. The agricultural chemical component may be internally arranged in the core, the shell or the two. If the agricultural chemical component is present in the shell, at least a portion of the agricultural chemical component may be coated or otherwise applied to the outer surface of the shell. In some instances, the agricultural chemical component is only located in the core and the shell is substantially free of (e.g., comprising less than 1 weight %) agricultural chemical components or free of (e.g., comprising 0 weight %) agricultural chemical components.

[0031] The nanostructured agricultural chemical delivery carrier functions by allowing the shell and core to biodegrade upon a triggering event. In operation, one or more nanostructured agricultural chemical delivery carriers are placed near a plant. The nanostructured agricultural chemical delivery carrier may be buried below the ground or below the soil where the plant is located. Alternatively, the nanostructured agricultural chemical delivery carrier may be arranged on the ground or on the soil where the plant is located. In some other examples, a portion of the nanostructured agricultural chemical delivery carrier may be arranged on the ground or on the soil where the plant is located, and another portion of the nanostructured agricultural chemical delivery carrier may be buried below the ground or below the soil where the plant is located. When the nanostructured agricultural chemical delivery carrier is placed near the plant, the plant itself may or may not sprout or be in any other growth stage.

[0032] During the triggering event, the shell, core, or each of the two polymer materials will begin to degrade. This results in controlled release of the agricultural chemical component from the shell, core, or the two. Some examples of triggering events include exposing the nanostructured agricultural chemical delivery vehicle to a predetermined enzyme, a predetermined pH, exposing the nanostructured agricultural chemical delivery vehicle to a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source, or a combination thereof. Some examples of biological secretions include exudates secreted from plant pathogens, and insects, weed species, or a combination thereof. Some examples of exudates may include enzymes, minerals, hormones, growth factors, etc. When the shell, core, or the two polymer materials contain a substrate for a predetermined enzyme, exposure to a predetermined enzyme may be achieved. If the shell, core, or the two polymer materials are thermosensitive, exposure to a predetermined temperature may be achieved. If the shell, core, or the two polymer materials are hygrosensitive, exposure to a predetermined moisture may be achieved. If the shell, core, or the two polymer materials are photosensitive, exposure to a predetermined light source may be achieved. The predetermined pH may be within the range in which the core, shell, or the two polymer components may be degraded. For example, if the core, shell, or both comprise chitosan, degradation may occur at a pH of 6 or less.

[0033] The degradation of shell, core, or both affects the release profile of the agricultural chemical component when a triggering event occurs. For example, the degradation can be carried out at a constant rate or a variable rate. As a result, the release of the agricultural chemical component can be sustained release, extended release, alternating release, or delayed release.

[0034] Nanostructured agricultural chemical delivery vehicles can be produced according to many different methods. For example, the method for preparing nanostructured agricultural chemical delivery vehicles can include a coaxial electrospray method, which includes arranging a liquid core precursor composition in a first chamber of a coaxial distributor. The liquid core precursor composition can include a first polymer material and optionally includes an agricultural chemical component. In addition, a liquid shell precursor can be located in a second chamber of the coaxial distributor. The liquid shell precursor composition includes a second polymer material and optionally includes an agricultural chemical component. Once each chamber is loaded. A voltage is applied to the coaxial distributor.

[0035] The substrate is located below the outlet of the coaxial dispenser. A voltage is applied to the substrate. Once the voltage is applied to both the coaxial dispenser and the substrate, the liquid core precursor and shell precursor flow from their respective chambers to the substrate to form a nanostructured agricultural chemical delivery vehicle.

[0036] Coaxial distributor and substrate are each formed by conductive material.Some examples of conductive material include stainless steel, copper, etc. For promoting the flow from coaxial distributor to substrate, the voltage applied to each component is different. For example, the voltage applied to coaxial distributor is about 15kV to about 40kV, about 20kV to about 35kV, less than, equal to or greater than about 15kV, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40kV positive DC voltage. In addition, the voltage applied to substrate is about 10kV to about 15kV, about 2kV to about 10kV, less than, equal to or greater than about 10kV, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15kV negative DC voltage. The voltage applied can contribute to the flow of control core precursor and shell precursor. For example, the flow of core precursor and shell precursor can be substantially equal. Or, the flow of core precursor and shell precursor is different. Make flow different can contribute to the size of regulating nanostructured agricultural chemicals delivery carrier or the thickness of core and shell separately. As an example, the flow rates of the core precursor and the shell precursor are independently about 0.01 ml / hour to about 0.60 ml / hour, about 0.05 ml / hour to about 0.40 ml / hour, less than, equal to, or greater than about 0.01 ml / hour, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60 ml / hour.

[0037] Throughout this document, values ​​expressed in range format should be interpreted in a flexible manner to include not only the numerical values ​​explicitly stated as limits of the range, but also all individual numerical values ​​or sub-ranges encompassed within the range, as if each numerical value and sub-range were explicitly stated. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted to include not only about 0.1% to about 5%, but also individual values ​​(e.g., 1%, 2%, 3% and 4%) and sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise noted, the expression "about X to Y" has the same meaning as "about X to about Y". Similarly, unless otherwise noted, the expression "about X, Y or about Z" has the same meaning as "about X, about Y or about Z".

[0038] In this document, nouns without quantifiers are used to include one or more, unless the context clearly dictates otherwise. Unless otherwise indicated, the term "or / or" is used to refer to a non-exclusive "or / or". The expression "at least one of A and B" or "at least one of A or B" has the same meaning as "A, B, or A and B". In addition, it should be understood that the words or terms used in this document and not otherwise defined are for descriptive purposes only and not for limiting purposes. The use of any section headings is intended to assist in reading the document and is not to be construed as limiting; information related to the section heading may appear within or outside that particular section.

[0039] In the methods described herein, except when the temporal order or order of operation is clearly recorded, the actions can be performed in any order without departing from the principles of the present invention. In addition, unless the clear claim language states that the specified actions are performed separately, they can be performed simultaneously. For example, the claimed action of performing X and the claimed action of performing Y can be performed simultaneously in a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0040] The term "about" as used herein can allow for a certain degree of variability in values ​​or ranges, for example, within 10%, within 5%, or within 1% of the value or range limits, and includes the exact value or range. The term "substantially" as used herein refers to a large portion or majority, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or greater, or 100%. As used herein, the term "substantially free" may mean having no or insignificant amounts such that the amount of material present does not affect the material properties of the composition containing the material, such that from about 0 wt % to about 5 wt %, or from about 0 wt % to about 1 wt %, or about 5 wt % or less, or less than or equal to about 4.5 wt %, 4 wt %, 3.5 wt %, 3 wt %, 2.5 wt %, 2 wt %, 1.5 wt %, 1 wt %, 0.9 wt %, 0.8 wt %, 0.7 wt %, 0.6 wt %, 0.5 wt %, 0.4 wt %, 0.3 wt %, 0.2 wt %, 0.1 wt %, 0.01 wt %, or about 0.001 wt % or less, or about 0 wt % of the composition is the material.

[0041] The polymers described herein may be terminated in any suitable manner. In some embodiments, the polymers may be terminated with terminal groups independently selected from: a suitable polymerization initiator, -H, -OH, substituted or unsubstituted (C1 to C2) interspersed with 0, 1, 2, or 3 groups independently selected from -O-, substituted or unsubstituted -NH-, and -S-. 20 ) hydrocarbon group (e.g., (C1 to C 10 ) alkyl or (C6 to C 20 ) aryl), poly(substituted or unsubstituted (C1 to C 20 )alkyloxy), and poly(substituted or unsubstituted (C1 to C 20 )alkylamino).

[0042] Example

[0043] Various embodiments of the present invention may be better understood by reference to the following examples which are provided by way of illustration.The present invention is not limited to the examples given herein.

[0044] Material

[0045] Cellulose acetate (180955, average Mn=30,000 by GPC), chitosan (448869, low molecular weight), zein (Z3625), starch from corn (S4126), polycaprolactone (440744, average M n =80000), copper (II) sulfate (C1297), formic acid (695076, ACS reagent), acetic acid (695092, ACS reagent), protease from Streptomyces griseus (P5147, type XIV, ≥3.5 units / mg), α-amylase from Aspergillus oryzae (10065, about 30 units / mg), buffer solution (1094361000, citric acid / sodium hydroxide, pH=5), DI water (8483331000, pH=7) were purchased from Sigma-Aldrich. Peters Professional 20-20-20 Universal Fertilizer (SKU#E99290) was purchased from Everris Na Inc. All chemicals were used without further purification.

[0046] Selection of polymers, agrochemicals, and solvents

[0047] Selection of polymers. To achieve pH and enzyme responsiveness, different types of biopolymers are blended. Chitosan is selected to achieve pH responsiveness due to its pH sensitivity. The soluble-insoluble transition of chitosan occurs when its pKa value is pH 6.0 to 6.5. In general, when the pH is higher than 6.0, the amine groups are deprotonated, making chitosan insoluble; when the pH is lower than 6.0, the amine groups are protonated, making chitosan a water-soluble cationic polyelectrolyte. Starch and zein can be degraded by amylases and proteases secreted by plant pathogenic fungi in the soil, and are therefore selected to achieve enzyme responsiveness. Additional polymers such as cellulose acetate (CA) and polycaprolactone (PCL) are incorporated to adjust the surface properties and morphology of the nanostructure. In particular, CA is a common derivative of cellulose and is selected as an added polymer because of its hydrophobicity, which can prevent the rapid passive diffusion of agricultural chemicals in the early release stage. PCL is a biodegradable synthetic biomaterial and was selected to improve electrospray processing stability and the morphology of the resulting nanostructures. In addition, PCL exhibits a rapid degradation rate compared to other polyesters (e.g., polyhydroxybutyrate, polylactic acid, and poly(1,4-butene) succinate).

[0048] Selection of agricultural chemicals. An agricultural chemical mixture containing selected micronutrients and macronutrients was used. Micronutrients are important for crop growth and nutrition, but also play a role in pathogen (fungus, bacteria) defense. Cu (CuSO4 as a model chemical) was selected as a model micronutrient because of its importance to plant health and growth and as a plant disease immunity activator. Copper is essential for many important metabolic pathways, including those involved in secondary metabolism and abiotic / biotic stress responses, and it is used to effectively promote plant resistance against pathogens. Cu also has direct antimicrobial activity against a range of microorganisms. The macronutrients used in the agricultural chemical mixture include nitrogen (N), phosphorus (P) and potassium (K), which are fertilizer components (collectively referred to as "NPK") and are required by plants at high levels. Commercial fertilizer (Peters professional 20-20-20 universal) was selected as the NPK source.

[0049] Agrochemical mixtures (e.g., CuSO4 and NPK fertilizers) were incorporated into both the core and shell polymer materials by direct solution fusion. The optimal agrochemical concentrations and compositions of individual micro / macronutrients were determined based on their solubility in a "green" solvent system (acetic acid / formic acid / H2O mixture), but we note that this may be crop and application specific.

[0050] Selection of solvent. Due to the complexity of various polymers and agricultural chemicals, it is necessary to wisely select solvents to form uniform precursor solutions for subsequent electrospray processing. In order to comply with the scope of sustainable agriculture, toxic organic solvents commonly used for polymer electrospraying are avoided. Acetic acid / H2O mixtures "generally recognized as safe" (GRAS, Generally Recognized as Safe) by the U.S. Food and Drug Administration (FDA) are selected as starting solvents to dissolve biopolymers and agricultural chemicals. The solubility of polymers and agricultural chemicals in this "green" solvent system is acceptable (data not shown), except for starch and CuSO4. To further improve the solubility of these analytes, formic acid (also a "GRAS" solvent) is added to AA / H2O to form a final solvent system, for example, FA / AA / H2O. After optimization, FA / AA / H2O ratios are determined at 40 / 40 / 20 (v / v / v / ) to achieve the best solubility of polymers and agricultural chemicals. It is noteworthy that FA / AA / H2O can dissolve both ionic micronutrients and NPK fertilizers, and traditional organic solvents generally lack this ability.

[0051] Preparation of precursor solution for coaxial electrospray

[0052] Three types of core-shell nanostructures with different shell polymer compositions and agrochemical concentrations in the core and shell were prepared. Type I nanostructures (fast release) were designed to have a more hydrophilic shell with the same amount of agrochemicals in the shell (50%) and core (50%); Type II nanostructures (intermediate release) were designed to have a more hydrophobic shell with less agrochemicals in the shell (25%) and more agrochemicals in the core (75%); and Type III nanostructures (slow release) were designed to have the most hydrophobic shell with agrochemicals only in the core (100%). The detailed formulas for synthesizing different types of core-shell nanostructures are shown in Table 1.

[0053] Table 1. Core and shell compositions used to synthesize different types of responsive core-shell nanostructures.

[0054]

[0055] To prepare the shell precursor solution, starch and PCL were first dispersed in formic acid and stirred at ambient temperature for 10 hours, and then acetic acid and water were added to the solution, followed by stirring for another 2 hours. Chitosan and CuSO4 were then dispersed in the resulting solution and stirred for another 10 hours. Finally, cellulose acetate, zein, and macronutrient fertilizer components were added to the polymer solution and then stirred for 2 hours to obtain the shell precursor solution.

[0056] To prepare the core precursor solution, PCL was dispersed in formic acid and acetic acid and the mixture was stirred at ambient temperature for 4 hours. Subsequently, water and CuSO4 were added to the solution, followed by stirring for another 8 hours. Finally, chitosan, cellulose acetate, and macronutrient fertilizer components were added to the polymer solution, followed by stirring for 4 hours to obtain the core precursor solution.

[0057] Synthesis of responsive core-shell nanostructures using coaxial electrospray

[0058] Shell and core precursor solution are filled into 10mL BD Luer-Lok tip plastic syringe.The plastic syringe is connected to a stainless steel (AISI 304) coaxial needle (90° blunt end) with a core needle diameter of 0.9 / 0.6mm (OD / ID) and a shell needle diameter of 1.7 / 1.4mm (OD / ID).Electrospray device (professional laboratory device, DOXA Microfluidics, Málaga, Spain) includes a high voltage power supply, a plate collector, and two syringe pumps.During electrospraying, a positive DC voltage of 30kV is applied to the stainless steel coaxial needle and a negative voltage of 5kV is applied to the plate collector; and the distance between the needle tip and the collector (i.e., the plate collector covered with aluminum foil) surface is set to 15cm.Core and shell solution flow rates are controlled respectively with different syringe pumps.For core and shell, the flow rate for synthesizing nanostructures is 0.2ml / hour and 0.2ml / hour. It is worth noting that to study the effect of core and shell flow rates on the morphology of nanostructures, three other flow rates were studied, for example, (1) core: 0.1 ml / hour, shell: 0.1 ml / hour; (2) core: 0.1 ml / hour, shell: 0.2 ml / hour; and (3) core: 0.2 ml / hour, shell: 0.4 ml / hour were applied to synthesize nanostructures. The electrosprayed nanostructures were collected as random overlay coatings on aluminum foil; these structures were easily separated from the foil using a brush and collected for further use.

[0059] Physicochemical properties of responsive core / shell nanostructures

[0060] The morphology of the electrosprayed nanostructures was characterized by a Zeiss Ultra Plus field emission scanning electron microscope (SEM). The diameter of the nanofibers was measured using ImageJ software (n=50). The core-shell structure was characterized by ultra-high resolution transmission electron microscopy (TEM). The distribution of elements in the nanostructure was characterized by energy dispersive X-ray spectroscopy (EDS). The water contact angle was measured by an internal system (MET-6, Nanoscale System Center, Harvard University) that captured digital images of the droplets and then used an insert ImageJ to determine the contact angle. BET (Brunauer-Emmett-Teller) specific surface area, total pore volume and average pore size were characterized by NOVAtouch (Quantachrome Instruments). Fourier transform infrared (FT-IR) spectra were obtained by a Nicolet iS50 FTIR spectrometer (Thermo).

[0061] Study on the release kinetics of agricultural chemicals

[0062] For pH responsive release, the nanostructures were dispersed in a buffer solution of pH 5 and water of pH 7. For enzyme responsive release, the nanostructures were dispersed in a solution with a total enzyme concentration of 1 U / ml. Specifically, protease (14.3 mg) and α-amylase (1.7 mg) were added to 50 ml DI water (pH = 7) and mechanically stirred for 1 hour to form a uniform enzyme solution. The control group was the same solution without enzyme.

[0063] The same concentration of nanostructures was used for the release kinetics studies and the greenhouse studies; for one plant, 2.64 mg / ml was used, equivalent to 132 mg of nanostructures in 50 ml of HO (additional details are as follows). Specifically, 13.2 mg of nanostructures were dispersed in 5 ml of the above solution; triplicate samples were set up. The obtained suspension was immersed in a water bath sonicator for 5 minutes to disperse the nanostructures. The solution containing the nanostructures was first centrifuged (at 3000 rpm for 20 minutes) at predetermined intervals and then quenched for the determination of Cu 2+200 μl of supernatant was extracted and collected for release kinetics. The Cu content of the sample was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES; iCAP 6500; Thermo Fisher Scientific, Waltham, MA). Subsequently, another 200 μl of the corresponding solution was added back to the original solution to maintain the volume at 5 ml. The Cu at each time point was calculated. 2+ The release percentage is calculated as:

[0064]

[0065] Where W 0(Cu) Cu in nanostructure 2+ The initial weight (due to the Cu in the nanostructure 2+ Load percentage × W0 measurement), W Cu is the Cu released from the solution at each time point 2+ weight.

[0066] Greenhouse experiment

[0067] For greenhouse experiments, soybean (Glycine max L.) and wheat (Triticum aestivum L.) seeds were germinated in 36 chambers (5.66×4.93×5.66 cm) plastic liners (1 seed / chamber) filled with soilless potting mix (ProMix BX. Premier Hort Tech, Quakertown, PA, USA). Type II nanostructures were selected for greenhouse experiments due to their high pH sensitivity under healthy soil conditions. After two and three weeks, uniform-sized seedlings of soybean and wheat with 3 to 4 leaves were transferred to new pots containing 350 mL of Promix modified with Type II nanostructures at 132 mg per pot, respectively, equivalent to 25 mg NPK and 0.85 mg Cu in total. Treatments with / without additional equal amounts (25 mg) of Cu or 4 times higher levels but in accordance with conventional application recommendations (100 mg) of Cu were included as controls. To prepare the growth medium, each pot containing 350mL Promix was initially improved with 50mL of DI and left to stabilize for 24 hours. The improvement was weighed based on the required amount in Promix and suspended in 30mL DI. After sonication for 30 seconds with a 500W probe sonicator (FB505, FisherScientific, Pittsburgh, PA), the nanosuspension was added to Promix and manually mixed to achieve homogeneity. Thirty mL of DI was applied to the control. Plants were cultivated in a complete randomized block design under standard lighting and temperature conditions (25°C and 22°C for day and night, 60% to 70% relative humidity, and 16,500× light intensity). Six replicates were used for each treatment. Soybean and wheat were harvested 4 and 8 weeks after sowing, respectively; leaf relative chlorophyll content, PS1 center activity, quantum yield of other uncontrolled (non-photochemical) losses (PhiNO), and linear electron flow (LEF) were measured 5 and 13 days after transplanting using a portable PhotosynQ (PHOTOSYNQ INC., USA).

[0068] Element measurement

[0069] Leaf, root and grain tissue samples of soybean and wheat were collected at harvest, washed, and then rinsed with 0.01% nitric acid and DI to remove any adhering particles. The samples were dried at 60°C for 2 days and ground into a fine powder. About 0.2 mg of sample was weighed and digested with 5 mL of plasma pure HNO3 at 115°C for 45 minutes using a heating block. The digest was diluted with DI and analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) (iCAP 6500, Thermo Fisher Scientific, Waltham, MA). For quality control, blank controls (no plant tissue) and standard reference materials (NIST-SRF 1570a and 1547, Metuchen, NJ) were prepared according to the same procedure. Yttrium (internal standard) was injected for each run. Continuous calibration verification sample analysis was performed for every 15 samples.

[0070] Statistical analysis

[0071] The Student t test was used to calculate the significant differences between each treatment and control at p≤0.05 or p≤0.01. One-way ANOVA followed by the Tukey-Kramer multiple comparison test was also used to determine the significant differences at p≤0.05. Data are expressed as mean ± standard error (SE).

[0072] Results and discussion

[0073] “Green” synthesis of responsive core-shell nanostructures for agrochemical delivery

[0074] Design strategies for biological and abiotic stimuli-responsive nanostructures with tunable surface hydrophobicity. Figure 1A The design strategies of biodegradable, pH and enzyme responsive core-shell nanostructures are summarized. Shell polymers are designed to be responsive to pH changes and enzyme exposure, while core polymers are designed to release agricultural chemicals continuously for a long time. Specifically, chitosan is selected to achieve pH responsiveness due to its pH sensitivity. Starch and zein, which can be degraded by amylase and protease, are used to achieve enzyme responsiveness. Hydrophobic polymers (e.g., cellulose acetate / PCL) are used as core polymers for continuous and controlled release. In addition, different biopolymer compositions and agricultural chemical concentrations in shell and core are selected to achieve adjustable surface hydrophobicity in order to control and release kinetics of agricultural chemicals.

[0075] Fine-tuning the polymer / agrochemical composition and surface hydrophobicity of nanostructures. Figure 1BGreen synthesis of nanostructures using coaxial electrospray method is shown. To achieve spherical core-shell nanostructures and minimize the size to achieve the highest specific surface area, optimization is performed by adjusting the electrospray conditions (e.g., core / shell polymer flow and voltage) and precursor solutions (e.g., shell and core polymer composition and agrochemical concentration).

[0076] Three types of core-shell nanostructures (called Type I, II, and III) with different biopolymer / agricultural chemical compositions in the shell and core were synthesized to determine the ability to have adjustable surface hydrophobicity and agrochemical release kinetics. Specifically, Type I nanostructures were designed to have a hydrophilic surface; Type II nanostructures were designed to have a hydrophobic surface; and Type III nanostructures were designed to have the most hydrophobic surface. Importantly, the total agrochemicals in these three nanostructures were the same; however, the ratio of agrochemicals in the core and shell was different.

[0077] Morphological characteristics of responsive core-shell nanostructures

[0078] The morphology of core-shell nanostructures. Fig. 2 shows the morphology and size distribution of three different core-shell nanostructures. After the electrospray parameters (voltage, flow rate, distance from needle to collector, etc.) are optimized, all three types of nanostructures show regular spherical shapes. The average diameters of I, II and III type nanostructures are 170 ± 110nm, 160 ± 89nm and 159 ± 84nm respectively. All electrospray nanostructures are easily removed from substrate (aluminum foil). It is worth noting that the size of electrospray particles is usually greater than 200nm.

[0079] Determination of core-shell structure. To verify and characterize the core-shell structure, high-resolution TEM was used. Figure 3A As shown in , the nanostructure (type I) shows a shell thickness of about 30nm and a clear boundary between the core and the shell, confirming the expected design. In addition, TEM-EDS was performed to verify the distribution of agricultural chemicals in the core-shell nanostructure. As shown in 3B to E, the element mapping of Cu, S, P, and K shows the nanostructure morphology and highlights the uniform distribution of agricultural chemicals (e.g., CuSO4 and NPK fertilizer) in the nanostructure.

[0080] Effect of core and shell electrospray flow rate on nanostructure morphology. Type I material was used as a model to study the effect of core and shell flow rate on nanostructure morphology. The resulting nanostructures all showed a regular spherical morphology, and as the core and shell flow rate increased, the average diameter increased (e.g., 129 ± 80 nm, 169 ± 112 nm, and 249 ± 181 nm).

[0081] In addition, other aspects of the core-shell nanostructure may also be affected by flow. When the shell flow is 0.1 ml / hour, the shell thickness is very small. When the shell flow is increased to 0.2 ml / hour, the shell thickness is also increased. Further increasing the flow does not affect the core-shell structure, but will increase the overall size of the particle. These findings show that the highly adjustable properties of nanostructures in terms of both size and shell thickness; these characteristics can be easily adjusted to further affect and control the release kinetics of agricultural chemicals.

[0082] Physicochemical properties of core-shell nanostructures

[0083] Specific surface area of ​​core-shell nanostructures. The specific surface area of ​​the three nanostructures was analyzed by N2 adsorption-desorption isotherm measurement. The N2 adsorption-desorption diagram can be classified as type II under Brunauer classification. The adsorption behavior includes adsorption in the low pressure region, gradually increasing adsorption in the intermediate P / P0 region, and further increasing adsorption in the high pressure region. Table 2 summarizes the microstructures of different types of core-shell materials.

[0084] Table 2. Microstructures of different types of responsive core-shell nanostructures.

[0085]

[0086] Type I, II, and III nanostructures showed similar BET surface areas (14.23, 15.52, and 18.29 m 2 Nanostructures with high specific surface areas will be able to effectively load reduced amounts of agrochemicals compared to conventional bulk fertilizers and can be used to enhance agrochemical efficacy while minimizing potential negative environmental health effects associated with the effects of agrochemicals on non-target species.

[0087] Chemical structure of core-shell nanostructures. The characteristic peaks of CA, CS, zein, starch, and PCL are evident in the FTIR spectra of the three nanostructures. Specifically, the characteristic peaks of CA are located at about 3450 (-OH stretching), 1726 (-C=O stretching), 1367 cm-1, and 1370 cm-2, due to the vibration of acetate groups. -1 (C-CH3 stretching), and 1234 (COC stretching). At 2940 and 2870 cm -1 (-CH2-), 1726cm -1 (-C=O), 1246cm -1 The characteristic peaks of PCL were observed at (COC), and these peaks overlapped with the characteristic peaks of CA. The spectrum showed characteristic peaks of chitosan, including -1 The strong and broad peaks at 2940 and 2870 cm-1 are caused by the overlapping peaks of -OH stretching vibration and -NH stretching.-1 The peak at 3345 cm -1 (NH stretching vibration), 2940cm -1 and 2870cm -1 (CH stretching vibration of aliphatic groups), and 1644 cm -1 (Amide I) and 1527 cm -1 The amide I peak is attributed to C=O stretching vibration, while the amide II peak is derived from NH bending and CN stretching vibration. The spectrum also shows typical peaks of starch skeleton. For example, at 1156 and 1050 cm -1 The peak observed at 831 cm indicates the presence of -CO- in glucose (CO deformation), while the peak at 831 cm -1 (COC stretch) and 735cm -1 The peaks observed at (COC bending) correspond to the backbone stretching and bending vibrations of starch.

[0088] The characteristic peaks of CA, PCL, CS, zein, and starch in the core-shell nanostructures confirm that the composite nanostructures were successfully formed by physical blending / mixing. The characteristic peaks of the nanostructures (polymer blends) observed from the spectrum have a slight shift compared to the individual CA / CS / zein / starch / PCL analytes, which may be due to the interactions (hydrogen bonds) in each component. In addition, the type I nanostructures exhibit significant characteristic peaks compared to the type II and type III nanostructures, which may be due to the differences in shell polymer composition between the materials. Note that the core polymer composition of type I, II, and type III nanostructures is the same (e.g., CA / CS / PCL=25 / 25 / 50, 2%, w / v). The shell polymer composition of type I nanostructures is CA / CS / zein / starch / PCL=35 / 30 / 15 / 15 / 5 (3%, w / v), while the shell polymer composition of type II and type III nanostructures is CA / CS / zein / starch / PCL=40 / 30 / 10 / 10 / 10 (3%, w / v). Such compositional differences in the shell allow for tunable surface hydrophobicity and agrochemical release kinetics.

[0089] Release kinetics of core / shell nanostructures under different conditions

[0090] The Cu from core-shell nanostructures was investigated under different pH conditions and in the presence or absence of specific enzymes. 2+ Release kinetics as a function of time.

[0091] Release kinetics under different pH conditions. The cumulative release of Cu from the core-shell nanostructures in buffer solution (pH 5.0) and water (pH 7.0) at 25 °C was Figure 4A & B. Type I nanostructures exhibit Cu at pH 7 2+ A clear burst of release and about 90% of the Cu 2+ released from the nanostructures, although more Cu was released within the first 6 h at pH 5 (100%). 2+ This is as expected and is due to the pH sensitive nature of chitosan. The system quickly reaches equilibrium with approximately 92% release at pH 7 and 100% release at pH 5. Cu 2+ The cumulative release at pH 5 was approximately 14% higher than that at pH 7, indicating a measurable but modest pH responsiveness. This is likely due to the hydrophilic nature of the type I nanostructures, which contain a more hydrophilic shell. This hydrophilic surface easily promotes wetting of the nanostructures, and most of the Cu in this fraction 2+ Dissolves freely in water.

[0092] Since type I nanostructures showed rapid release within 6 hours, additional time point studies were conducted on the release kinetics of type II nanostructures within 24 hours. Figure 4B As shown in Figure 2, type II nanostructures showed significantly lower Cu at pH 7. 2+ The cumulative release of Cu 2+ The Cu was released from the nanostructure within the first 3 hours, and the system continuously released Cu 2 + and reached 63% at 24 h. As expected, more Cu 2+ (97%) was released within the first 3 hours, and then the system quickly reached equilibrium. 2+ The release at pH 5 was approximately 37% higher than that at pH 7, indicating a higher level of pH responsiveness. This may be due to the hydrophobic nature of the type II nanostructures, which have a more hydrophobic shell. With a more hydrophobic surface, the wettability of the nanostructures is significantly reduced, and only the nanostructure surface is in contact with water. Therefore, less Cu is released due to the lack of water contact. 2+ When the nanostructure is under neutral conditions, such a hydrophobic surface can retain and hold more agrochemicals. When the pH drops to 5, chitosan starts to become more soluble and more Cu 2+ Release from nanostructures.

[0093] Agrochemical release kinetics under enzymatic conditions. Cumulative release of Cu from core-shell nanostructures at pH 7 and 25 °C in the presence or absence of protease and α-amylase. Figure 4C & D. Figure 4C As shown in Figure 2, Type I nanostructures exhibited Cu 2+ in both enzyme solution and control (water) within the first 6 hours. 2+ There is a clear burst of Cu release (90%), which is largely due to the hydrophilic character of the particles. For the nanostructures in the absence of enzyme, the system quickly reaches equilibrium after 6 hours with approximately 90% release. However, for the nanostructures in solution with enzyme, the accumulated Cu 2+ The percentage release increased to 100% at day 3, 18% higher than the sample without enzyme, indicating the time dependence of biopolymer degradation.

[0094] like Figure 4B As shown in Figure 2, type II nanostructures exhibited significantly lower accumulated Cu compared to type I nanostructures in the first 3 hours in the presence and absence of enzyme. 2+ The release percentage was 40% and 51% respectively. 2 + The release of Cu was about 55% in the presence of enzyme and 63% in the absence of enzyme at day 1. 2+ The release profile had minimal effect, indicating low enzyme responsiveness. This may be due to the hydrophobic nature of type II nanostructures, which contain a more hydrophobic shell. Such surface hydrophobicity is not conducive to enzyme adhesion, which inhibits biopolymer degradation. However, for the more hydrophilic type I nanostructures, the Cu release was significantly improved in the presence of enzymes. 2+ The release is palpable.

[0095] It is noteworthy that different plant species may require different amounts of nutrients during seedling development and plant growth and those requirements may change within the life cycle of crops. Therefore, it is important to develop a multifunctional nano platform based on biopolymers with adjustable responsive agricultural chemicals release kinetics (which may then be applicable to different plant species). In addition, the developed core-shell nanostructure shows multifunctional stimulus responsiveness. Specifically, type II nanostructures are more pH sensitive and can be suitable for plants under healthy conditions (wherein the low pH of the rhizosphere induces agricultural chemicals to release). On the contrary, type I nanostructures are more enzyme sensitive and can be used for pathogen infection conditions (when fungi release extracellular enzymes to induce agricultural chemicals to release).

[0096] Greenhouse research

[0097] Greenhouse experiments were conducted to evaluate the ability of type II responsive core / shell nanostructures (containing 25 mg NPK and 0.8 mg Cu) to deliver key macronutrients and micronutrients to soybean and wheat model plants grown under soil conditions ( Figure 1C ). It is worth mentioning that type II nanostructures were selected for greenhouse experiments due to their high pH sensitivity under healthy soil conditions.

[0098] Plant photosynthesis. The effects of responsive core-shell nanostructures (loaded with patterned NPK and Cu) on photosynthesis were studied. Figure 5A Relative chlorophyll content, an indirect measure of photosynthesis and productivity of 4-week-old soybean seedlings, is shown; nanostructures with 25 mg NPK and Cu loading produced plants with 34.3% higher relative chlorophyll content than ionic controls with equivalent NPK and Cu content. The relative chlorophyll content in the nanostructure treatment group was equivalent to 100 mg of conventional NPK and Cu, which had a 4-fold higher agrochemical content than the responsive nanostructures. It is noteworthy that for 8-week-old wheat seedlings, the nanostructure-treated plant group did not show significant differences in relative chlorophyll content compared to all other treatments.

[0099] Similar results are evident in the activity of the PS1 center in photosystem I, which is involved in the reception and transfer of electrons ( Figure 5B ). Soybean seedlings exposed to the nanostructures produced 54.6% and 41.2% more than the control and plants treated with conventional 25 mg NPK and Cu, respectively (p≤0.05). More importantly, the PS1 centers in photosystem I in the nanostructure-treated group were equivalent to the conventional NPK and Cu-exposed control group treated with four times higher model agrochemicals (100 mg compared to 25 mg in the nanostructure-treated group). For wheat seedlings, the nanostructure-treated plant group did not show significant differences in photosystem I compared to all other treatments.

[0100] in addition, Figure 5C PhiNO levels are shown for 8 week old wheat seedlings. PhiNO measures the amount of incident light that is neither used for photosynthesis nor dissipated, effectively causing potential damage to the leaves. This is highly important, especially in areas that are highly exposed to long-term daylight conditions due to climate change. Plants exposed to nanostructures with 25 mg NPK and Cu showed similar values ​​to plants treated with 25 mg NPK and Cu, but showed significantly lower values ​​of 28.5% than plants treated with 100 mg NPK and Cu, indicating the potential protective effect of the nanostructures in wheat leaves. For soybean seedlings, the groups treated with the nanostructures did not show significant differences in PhiNO.

[0101] in addition, Figure 5DLinear electron flow (LEF) of 8-week-old wheat seedlings is shown. LEF represents the amount of energy that moves through chloroplasts after exposure to light. It is worth noting that the group treated with nanostructures (with 25 mg NPK and Cu) showed significantly higher values ​​(187.7) compared to the control (87.2) and all other treatments (88.8 to 136.4), indicating enhanced electron flow and carbon fixation (p≤0.05). For soybean seedlings, the group treated with nanostructures did not show significant differences in LEF.

[0102] In summary, the results show that responsive core-shell nanostructures are versatile and promising platforms that can enhance photosynthesis in a manner that responds to the needs of different plant species. Specifically, compared with all other treatments, the nanostructured plant group with 25 mg NPK and Cu showed significant differences in relative chlorophyll content and photosystem I in 4-week-old soybean seedlings, as well as significant differences in LEF in 8-week-old wheat seedlings, indicating that the effects of nanostructures on photosynthesis are plant-specific. Photosynthesis converts solar energy, water, and carbon dioxide into ATP and glucose, and the enhancement can be attributed to the higher efficiency of agricultural chemical delivery and utilization. More specifically, in soil, compared with conventional fertilizer application situations, responsive core-shell nanostructures can release NPK and Cu at the right time and in the right dosage. More mechanized plant-specific studies will be conducted in the future to optimize plant growth while adjusting agricultural chemical delivery strategies, which are highly adjustable, as we have shown in this study.

[0103] Figure 6 shows the zinc (Zn) content in leaves of 4-week-old soybean seedlings ( Fig. 6A ) and sodium (Na) content ( Figure 6B ) is significantly increased in the sprouts of soybeans from nanostructure treatment. Specifically, relative to conventional 25mg NPK with Cu (68mg / kg) and 100mg NPK with Cu (55.1mg / kg), nanostructure application also induced significantly higher Zn accumulation (78.6mg / kg). Zn is involved in the production of auxin (important growth hormone). The Zn level raised not only improves plant growth, but also enhances the nutritional quality of soybean plants. In addition, Na content is 48.1% and 55.7% higher (p≤0.05) than control and conventional 25mg NPK with Cu respectively. Importantly, these findings show that NPK and Cu in nanoscale form can be potentially used to regulate the accumulation of other important micronutrients through potential biofortification strategies. However, other elements such as Cu, Ca, Si and Fe are not affected by nanostructures.

[0104] Fresh biomass. Compared to the control, the nanostructure treatment significantly increased the fresh biomass of soybean sprouts by about 37%. This increase in biomass was not obvious in the conventional NPK with / without Cu (25 mg) and NPK without Cu (100 mg) treatments. Similarly, only nanostructures and NPK with Cu (100 mg) significantly improved the sprout growth of wheat relative to the control; this increase was not found in any other treatment. Specifically, the nanostructure caused the sprout weight to be 79.8% and 44.0% higher than the NPK with Cu (100 mg) treatment and the control, respectively. Grain yield was not affected by any treatment (p≤0.05). Importantly, the increase in fresh biomass of wheat sprouts was not obvious in other treatments (e.g., 25 mg and 100 mg of both conventional NPK without Cu). Obviously, Cu treatment (both nanostructures and conventional 100 mg NPK) promoted the growth of fresh biomass of sprouts of both soybeans and wheat. Cu is an important micronutrient and can strengthen the plant immune system and subsequently enhance plant growth. The terms and expressions that have been used are used as terms of description rather than limitation, and the use of such terms and expressions is not intended to exclude any equivalent forms of the features shown and described or portions thereof, but it should be recognized that various modifications can be made within the scope of the embodiments of the present invention. Therefore, it should be understood that although the present invention has been specifically disclosed through specific embodiments and optional features, those of ordinary skill in the art may make modifications and changes to the concepts disclosed herein, and such modifications and changes are considered to be within the scope of the embodiments of the present invention.

[0105] Exemplary embodiments

[0106] The following exemplary embodiments are provided, the numbering of which should not be construed as designating a level of importance:

[0107] Aspect 1 provides a nanostructured agricultural chemical delivery carrier having a core-shell structure:

[0108] The core comprises a first polymeric material; and

[0109] The shell at least partially encapsulates the core, the shell comprising a second polymeric material,

[0110] in:

[0111] The core, the shell, or both comprise an agrochemical component distributed around the first polymeric material, the second polymeric material, or both; and

[0112] Release of the agrochemical component from the core, the shell, or both is triggered by exposure to at least one of: a predetermined enzyme, a predetermined pH, a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source.

[0113] Aspect 2 provides the nanostructured agricultural chemical delivery vehicle of aspect 1, wherein the nanostructured agricultural chemical delivery vehicle has an average diameter of about 150 nm to about 300 nm.

[0114] Aspect 3 provides the nanostructured agricultural chemical delivery vehicle of any one of Aspects 1 or 2, wherein the nanostructured agricultural chemical delivery vehicle has an average diameter of about 160 nm to about 170 nm.

[0115] Aspect 4 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 3, wherein the shell has a thickness of about 10 nm to about 50 nm.

[0116] Aspect 5 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 4, wherein the shell has a thickness of about 10 nm to about 40 nm.

[0117] Aspect 6 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 5, wherein the first polymer material and the second polymer material comprise polysaccharide-based biopolymers.

[0118] Aspect 7 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 6, wherein the first polymer material comprises cellulose acetate, chitosan, zein, corn starch, polycaprolactone, or a mixture thereof.

[0119] Aspect 8 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 7, wherein the first polymer material comprises cellulose acetate, chitosan, zein, corn starch, and polycaprolactone.

[0120] Aspect 9 provides the nanostructured agricultural chemical delivery vehicle of any one of Aspects 7 or 8, wherein:

[0121] the cellulose acetate is from about 30% to about 50% by weight of the first polymeric material;

[0122] The chitosan is about 20% to about 40% by weight of the first polymeric material;

[0123] the zein protein is from about 5% to about 20% by weight of the first polymeric material;

[0124] The corn starch is from about 5% to about 20% by weight of the first polymeric material; and

[0125] The polycaprolactone is from about 5% to about 20% by weight of the first polymeric material.

[0126] Aspect 10 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 7 to 9, wherein:

[0127] the cellulose acetate is from about 35% to about 45% by weight of the first polymeric material;

[0128] the chitosan is about 25% to about 35% by weight of the first polymeric material;

[0129] the zein protein is from about 10% to about 15% by weight of the first polymeric material;

[0130] The corn starch is from about 10% to about 15% by weight of the first polymeric material; and

[0131] The polycaprolactone is from about 10% to about 15% by weight of the first polymeric material.

[0132] Aspect 11 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 10, wherein the second polymer material comprises cellulose acetate, chitosan, polycaprolactone, or a mixture thereof.

[0133] Aspect 12 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 11, wherein the second polymer material comprises cellulose acetate, chitosan, and polycaprolactone.

[0134] Aspect 13 provides the nanostructured agricultural chemical delivery vehicle of any one of Aspects 11 or 12, wherein:

[0135] the cellulose acetate is from about 20% to about 30% by weight of the second polymeric material;

[0136] The chitosan is about 20% to about 30% by weight of the second polymeric material; and

[0137] The polycaprolactone is from about 40% to about 60% by weight of the second polymeric material.

[0138] Aspect 14 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 11 to 13, wherein:

[0139] the cellulose acetate is from about 23% to about 28% by weight of the second polymeric material;

[0140] The chitosan is about 23% to about 28% by weight of the second polymeric material; and

[0141] The polycaprolactone is from about 44% to about 56% by weight of the second polymeric material.

[0142] Aspect 15 provides the nanostructured agricultural chemical delivery vehicle of any of aspects 1 to 14, wherein the shell is about 45% to about 62% by weight of the nanostructured agricultural chemical delivery vehicle.

[0143] Aspect 16 provides the nanostructured agricultural chemical delivery vehicle of any of aspects 1 to 15, wherein the shell is about 47% to about 60% by weight of the nanostructured agricultural chemical delivery vehicle.

[0144] Aspect 17 provides the nanostructured agricultural chemical delivery vehicle of any of aspects 1 to 16, wherein the core is about 38% to about 55% by weight of the nanostructured agricultural chemical delivery vehicle.

[0145] Aspect 18 provides the nanostructured agricultural chemical delivery vehicle of any of Aspects 1 to 17, wherein the core is about 40% to about 53% by weight of the nanostructured agricultural chemical delivery vehicle.

[0146] Aspect 19 provides the nanostructured agrochemical delivery vehicle of any one of aspects 1 to 18, wherein the agrochemical component comprises a micronutrient, a macronutrient, a pesticide, a fungicide, or a mixture thereof.

[0147] Aspect 20 provides the nanostructured agricultural chemical delivery vehicle of aspect 19, wherein the micronutrient comprises copper, boron, zinc, manganese, iron, molybdenum, chlorine, or a mixture thereof.

[0148] Aspect 21 provides the nanostructured agricultural chemical delivery vehicle of aspect 20, wherein the copper is CuSO4.

[0149] Aspect 22 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 19 to 21, wherein the macronutrient comprises nitrogen, phosphorus, potassium, or a mixture thereof.

[0150] Aspect 23 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 22, wherein the agricultural chemical component is uniformly distributed around the shell and the core.

[0151] Aspect 24 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 23, wherein a majority of the total amount of the agricultural chemical component is in the core.

[0152] Aspect 25 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 24, wherein a majority of the total amount of the agricultural chemical component is in the shell.

[0153] Aspect 26 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 25, wherein the shell is free of the agricultural chemical component.

[0154] Aspect 27 provides the nanostructured agricultural chemical delivery carrier of any one of aspects 1 to 26, wherein the nanostructured agricultural chemical delivery carrier has a specific surface area of ​​about 10 m 2 / g to about 30m 2 / g.

[0155] Aspect 28 provides the nanostructured agricultural chemical delivery carrier of any one of aspects 1 to 27, wherein the nanostructured agricultural chemical delivery carrier has a specific surface area of ​​about 13 m 2 / g to about 20m 2 / g.

[0156] Aspect 29 provides the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 28, wherein the first polymeric material, the second polymeric material, or both are biodegradable.

[0157] Aspect 30 provides a method for preparing the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 29, the method comprising:

[0158] disposing a liquid core precursor composition in a first chamber of a coaxial dispenser, the liquid core precursor composition comprising the first polymeric material and optionally comprising the agrochemical component;

[0159] disposing a liquid shell precursor in a second chamber of the coaxial dispenser, the liquid shell precursor composition comprising the second polymeric material and optionally comprising the agrochemical component;

[0160] applying a voltage to the coaxial distributor;

[0161] applying a voltage to a substrate in flow communication with the coaxial distributor;

[0162] flowing the liquid core precursor composition from the first chamber to the substrate; and

[0163] The shell precursor composition is flowed from the second chamber to the substrate.

[0164] Aspect 31 provides the method of aspect 30, wherein the coaxial distributor comprises a conductive material.

[0165] Aspect 32 provides the method of aspect 31, wherein the conductive material is stainless steel.

[0166] Aspect 33 provides the method of aspects 30 to 32, wherein the coaxial dispenser comprises a plurality of needles.

[0167] Aspect 34 provides the method of any one of aspects 30 to 33, wherein the voltage applied to the coaxial distributor is a positive DC voltage of about 15 kV to about 40 kV.

[0168] Aspect 35 provides the method of any one of aspects 30 to 34, wherein the voltage applied to the coaxial distributor is a positive DC voltage of about 20 kV to about 35 kV.

[0169] Aspect 36 provides the method of any of aspects 30 to 35, wherein the voltage applied to the substrate is a negative DC voltage of about 1 kV to about 15 kV.

[0170] Aspect 37 provides the method of any of aspects 30 to 36, wherein the voltage applied to the substrate is a negative DC voltage of about 2 kV to about 10 kV.

[0171] Aspect 38 provides the method of any one of aspects 30 to 37, wherein the flow rates of the core precursor and the shell precursor are substantially the same.

[0172] Aspect 39 provides the method of any one of aspects 30 to 38, wherein the flow rates of the core precursor and the shell precursor are different.

[0173] Aspect 40 provides the method of any one of aspects 30 to 39, wherein the flow rate of the core precursor and the shell precursor is independently about 0.01 ml / h to about 0.6 ml / h.

[0174] Aspect 41 provides the method of any one of aspects 30 to 40, wherein the flow rates of the core precursor and the shell precursor are independently about 0.05 ml / h to about 0.4 ml / h.

[0175] Aspect 42 provides a method of using the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 41, the method comprising:

[0176] The nanostructured agricultural chemical delivery vehicle is placed in proximity to a plant.

[0177] Aspect 43 provides the method of aspect 42, wherein the plant does not germinate when the nanostructured agricultural chemical delivery vehicle is placed in proximity thereto.

[0178] Aspect 44 provides the method of any of aspects 42 or 43, further comprising triggering release of the agricultural chemical.

[0179] Aspect 45 provides the method described in Aspect 44, wherein triggering the release of the agricultural chemical comprises exposing the nanostructured agricultural chemical delivery vehicle to a predetermined enzyme, a predetermined pH, exposing the nanostructured agricultural chemical delivery vehicle to a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source, or a combination thereof.

[0180] Aspect 46 provides the method of aspect 45, wherein the biological secretions include exudates secreted from plant pathogens, and insects, weed species, or a combination thereof.

[0181] Aspect 47 provides the method of any one of aspects 44 to 46, wherein the release of the agricultural chemical is sustained release, extended release, alternating release, or delayed release.

[0182] Aspect 48 provides a plant fertilized by the nanostructured agricultural chemical delivery vehicle of any one of aspects 1 to 17.

Claims

1. A nanostructured agricultural chemical delivery carrier having a core-shell structure: The core comprises a first polymeric material; and The shell at least partially encapsulates the core, the shell comprising a second polymeric material, in: The core, the shell, or both comprise an agrochemical component distributed around the first polymeric material, the second polymeric material, or both; and Release of the agrochemical component from the core, the shell, or both is triggered by exposure to at least one of: a predetermined enzyme, a predetermined pH, a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source.

2. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the nanostructured agricultural chemical delivery vehicle has an average diameter of about 150 nm to about 300 nm.

3. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the shell has a thickness of about 10 nm to about 50 nm.

4. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the first polymer material comprises cellulose acetate, chitosan, zein, corn starch, polycaprolactone, or a mixture thereof.

5. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the first polymer material comprises cellulose acetate, chitosan, zein, corn starch, and polycaprolactone.

6. The nanostructured agricultural chemical delivery vehicle of claim 5, wherein: the cellulose acetate is from about 30% to about 50% by weight of the first polymeric material; The chitosan is about 20% to about 40% by weight of the first polymeric material; the zein protein is from about 5% to about 20% by weight of the first polymeric material; The corn starch is from about 5% to about 20% by weight of the first polymeric material; and The polycaprolactone is from about 5% to about 20% by weight of the first polymeric material.

7. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the second polymer material comprises cellulose acetate, chitosan, and polycaprolactone.

8. The nanostructured agricultural chemical delivery vehicle of claim 6, wherein: the cellulose acetate is from about 20% to about 30% by weight of the second polymeric material; The chitosan is about 20% to about 30% by weight of the second polymeric material; and The polycaprolactone is from about 40% to about 60% by weight of the second polymeric material.

9. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the shell is about 45% to about 62% by weight of the nanostructured agricultural chemical delivery vehicle.

10. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the core is about 38% to about 55% by weight of the nanostructured agricultural chemical delivery vehicle.

11. The nanostructured agrochemical delivery vehicle of claim 1, wherein the agrochemical component comprises a micronutrient, a macronutrient, a pesticide, a fungicide, or a mixture thereof.

12. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein a majority of the total amount of the agricultural chemical component is in the core.

13. The nanostructured agrochemical delivery vehicle of claim 1, wherein the shell is free of the agrochemical component.

14. The nanostructured agricultural chemical delivery carrier of claim 1, wherein the nanostructured agricultural chemical delivery carrier has a specific surface area of ​​about 10 m 2 / g to about 30m 2 / g.

15. The nanostructured agricultural chemical delivery vehicle of claim 1, wherein the first polymeric material, the second polymeric material, or both are biodegradable.

16. A method for preparing the nanostructured agricultural chemical delivery vehicle of claim 1, the method comprising: disposing a liquid core precursor composition in a first chamber of a coaxial dispenser, the liquid core precursor composition comprising the first polymeric material and optionally comprising the agrochemical component; disposing a liquid shell precursor composition comprising the second polymeric material and, optionally, the agrochemical component in the second chamber of the coaxial dispenser; applying a voltage to the coaxial distributor; applying a voltage to a substrate in flow communication with the coaxial distributor; flowing the liquid core precursor composition from the first chamber to the substrate; as well as The shell precursor composition is flowed from the second chamber to the substrate.

17. The method of claim 16, wherein the coaxial divider comprises a conductive material.

18. The method of claim 16, wherein the voltage applied to the coaxial divider is a positive DC voltage of about 15 kV to about 40 kV.

19. The method of claim 16, wherein the flow rates of the core precursor and the shell precursor are different.

20. The method of claim 16, wherein the flow rate of the core precursor and the shell precursor is independently about 0.01 ml / hour to about 0.6 ml / hour.

21. A method of using the nanostructured agricultural chemical delivery vehicle of claim 1, the method comprising: The nanostructured agricultural chemical delivery vehicle is placed in proximity to a plant.

22. The method of claim 21, wherein the plant does not germinate when the nanostructured agricultural chemical delivery vehicle is placed in proximity thereto.

23. The method of claim 21, further comprising triggering release of the agricultural chemical.

24. The method of claim 23, wherein triggering the release of the agricultural chemical comprises exposing the nanostructured agricultural chemical delivery vehicle to a predetermined enzyme, a predetermined pH, exposing the nanostructured agricultural chemical delivery vehicle to a predetermined biological secretion, a predetermined temperature, a predetermined moisture content, a predetermined light source, or a combination thereof.

Images