System for the biogenic synthesis of chitosan-copper nanoparticles using moringa leaf extract

Abstract

A biogenic nanoparticle synthesis system for the production of chitosan-copper nanoparticles using plant extract, wherein the system comprises the following: a sealed reaction vessel made of corrosion-resistant material, forming an inner reaction chamber configured to contain an aqueous copper salt solution and a plant extract mixture; a temperature control unit that is thermally coupled to the reaction vessel and configured to maintain the temperature inside the reaction chamber within a predetermined range between 25 degrees Celsius and 75 degrees Celsius with a tolerance of plus / minus one degree Celsius; a stirring unit consisting of a variable speed motor and a stirring shaft extending into the inner reaction chamber, wherein the stirring unit is configured to ensure uniform mixing at speeds between one hundred and one thousand revolutions per minute; a plant extract introduction unit consisting of a metered inlet line and a flow control valve configured to introduce an aqueous extract from Moringa oleifera leaves into the reaction chamber at a controlled rate to initiate the reduction of copper ions; a dosing unit for chitosan solution, consisting of a programmable peristaltic pump connected to a reservoir containing a chitosan solution dissolved in dilute acetic acid, wherein the dosing unit is configured to dispense the chitosan solution in a controlled dropwise manner into the reaction chamber; a pH monitoring unit with a pH probe protruding into the reaction chamber; a base addition unit consisting of a reagent reservoir with sodium hydroxide solution and a precision dosing pump to maintain a pH value of the reaction mixture of six plus / minus zero point five; a control unit that is operationally connected to the temperature control unit, the stirring unit, the plant extract feeding unit, the chitosan solution dosing unit, the pH monitoring unit and the base addition unit, wherein the control unit is configured to synchronize the temperature control, the reagent addition rate, the stirring speed and the pH correction to produce a stable colloidal suspension of chitosan copper nanoparticles.

Description

Application area of ​​the invention

[0001] The present invention relates to the fields of green nanotechnology, agricultural biotechnology, and sustainable pesticide formulations. In particular, the invention relates to a biogenic system for the synthesis of chitosan-copper nanoparticles using Moringa oleifera leaf extract as a natural reducing and stabilizing agent. Furthermore, the invention discloses a specific nanoparticle synthesis system for the controlled production of these nanoparticles on a laboratory and semi-commercial scale. Background of the invention

[0002] Modern agriculture is increasingly confronted with declining soil fertility, decreasing nutrient efficiency, environmental pollution from the excessive use of chemical fertilizers, and increased plant susceptibility to biotic and abiotic stressors. Conventional micronutrient preparations such as copper sulfate sprays and synthetic plant growth regulators often exhibit low bioavailability, rapid degradation, and limited physiological functionality. While chemically synthesized metal nanoparticles are effective, they require toxic reducing agents such as sodium borohydride or hydrazine, high energy input, and complex stabilization processes, posing environmental and occupational safety risks.

[0003] Chitosan, derived from chitin via alkaline deacetylation, is a biodegradable, biocompatible, and non-toxic polysaccharide with antimicrobial and plant growth-promoting properties. The integration of copper ions into nanoscale chitosan matrices enhances bioavailability, controlled release, and interaction with plant tissue. However, existing chitosan-metal systems are predominantly based on chemical synthesis methods and lack integrated phytochemical biofunctionalization.

[0004] The present invention addresses these limitations through a green synthesis route in which Moringa oleifera leaf extract is used as both a reducing and stabilizing agent for copper ions, resulting in biofunctionalized chitosan copper nanoparticles with multifunctional agronomic properties.

[0005] Agricultural productivity in the 21st century is increasingly limited by declining soil fertility, micronutrient imbalances, reduced nutrient efficiency, and increasing biotic and abiotic stressors. Intensive farming methods, monocultures, and the excessive use of synthetic fertilizers have led to soil degradation, loss of organic matter, disruption of beneficial microbial communities, and micronutrient deficiencies, particularly of transition metals such as copper. Copper plays a crucial role in plant physiological processes such as photosynthesis, respiration, lignin synthesis, pollen germination, and the activation of enzymes involved in the oxidative stress response, such as superoxide dismutase and polyphenol oxidase.However, the availability of copper in the soil is highly dependent on pH, redox potential, and complexation with organic matter, often leading to precipitation or immobilization and limiting plant uptake. Conventional copper fertilization with copper sulfate or other soluble salts frequently results in rapid leaching, surface runoff, or phytotoxic accumulation at higher doses. Consequently, there is a constant need for delivery systems that enable controlled release, improved bioavailability, and reduced environmental impact.

[0006] Conventional micronutrient preparations are typically applied as foliar fertilizers or soil amendments in ionic form. While these methods are inexpensive and widely used, they have inherent limitations. Ionic copper applied to foliage can rapidly oxidize or precipitate under environmental conditions, reducing its effective concentration before uptake. In soil, copper ions can bind strongly to clay minerals or organic ligands, decreasing their mobility and bioavailability. Furthermore, repeated application can lead to local accumulation, which can negatively impact soil microbial diversity and potentially cause phytotoxicity symptoms such as chlorosis, stunted root growth, and oxidative damage. These drawbacks highlight the inadequacy of traditional copper fertilization systems for efficient nutrient management.

[0007] To improve nutrient inefficiency, synthetic plant growth regulators and commercial biostimulants have been introduced into agriculture. These preparations often contain hormones, amino acids, humic substances, or algal extracts intended to increase the metabolic activity and stress tolerance of plants. Although such products can elicit measurable growth responses under controlled conditions, their efficacy in the field is inconsistent due to rapid degradation, volatility, and susceptibility to environmental influences. Many synthetic growth regulators are chemically unstable, have a limited half-life, and require repeated application to maintain their effectiveness. Furthermore, these products typically lack micronutrient supplementation capabilities and do not provide antimicrobial protection. They thus function more as single agents than as integrated solutions.

[0008] In recent years, nanotechnology has emerged as a promising approach to overcoming the limitations of conventional nutrient formulations. Metal and metal oxide nanoparticles exhibit a high surface-to-volume ratio, increased reactivity, and improved interaction with biological membranes. Copper oxide nanoparticles and other nanoscale micronutrient carriers have demonstrated higher uptake efficiency and delayed release compared to their macroscopic counterparts. However, most commercially available metal nanoparticles are synthesized via chemical reduction processes using strong reducing agents such as sodium borohydride, hydrazine hydrate, or ethylene glycol. These synthesis routes often require high temperatures, inert atmospheres, and additional stabilizing surfactants to prevent agglomeration.The use of hazardous chemicals generates toxic byproducts, increases energy consumption, and raises concerns regarding environmental sustainability and occupational safety. Residues of chemical stabilizers can remain in the final product and potentially cause phytotoxic or ecotoxic effects in agricultural applications.

[0009] Chitosan, a deacetylated chitin derivative primarily derived from crustacean shells, has garnered significant attention as a biodegradable and biocompatible biopolymer with antimicrobial and plant growth-promoting properties. Chitosan solutions are used as foliar sprays and seed treatments to enhance plant defenses, induce systemic resistance, and improve germination rates. However, in its pure form, chitosan exhibits limited solubility at neutral pH and forms viscous solutions that can hinder uniform distribution on leaf surfaces. Furthermore, its bioactivity is often concentration-dependent and can vary with molecular weight and degree of deacetylation. To enhance its functionality, researchers have developed chitosan nanoparticles through ionic gelation or crosslinking with substances such as tripolyphosphate.Although these nanoparticles have an increased surface area and bioavailability, they generally function as carriers without intrinsic integration of micronutrients, thus requiring separate nutritional supplementation.

[0010] Chitosan-metal nanocomposites have been proposed as multifunctional systems that combine the biopolymeric advantages of chitosan with the catalytic or nutritional properties of metal nanoparticles. Common fabrication methods for such composites often rely on the chemical reduction of metal salts in the presence of dissolved chitosan. These approaches frequently result in heterogeneous particle size distributions due to rapid nucleation and uncontrolled growth kinetics. Furthermore, the absence of natural stabilizers can lead to particle aggregation, broad polydispersity indices, and unstable suspensions that settle during storage. The lack of controlled surface biofunctionalization limits interaction with plant tissue and reduces the reproducibility of physiological responses.Furthermore, many of the described systems are limited to synthesis on a laboratory scale, without considering scalability or validation in the field.

[0011] Green synthesis methods that utilize plant extracts as reducing agents have established themselves as an environmentally friendly alternative to conventional chemical processes. Plant phytochemicals such as polyphenols, flavonoids, alkaloids, terpenoids, and ascorbic acid can donate electrons to metal ions, thus enabling nanoparticle formation under mild conditions. These approaches eliminate the need for toxic chemical reducing agents and can often be carried out at ambient conditions. However, many plant-mediated nanoparticle syntheses focus exclusively on metallic nanoparticles without embedding them in polymer matrices, resulting in limited colloidal stability and rapid agglomeration. Furthermore, variability in plant extract composition due to seasonal, geographical, or processing-related differences can impair the reproducibility of nanoparticle properties.Most green-synthesized nanoparticles are primarily investigated for antimicrobial or catalytic applications and less for their comprehensive agronomic performance.

[0012] Moringa oleifera has been extensively studied due to its rich phytochemical profile, which includes high concentrations of phenolic compounds, flavonoids, vitamins, amino acids, and natural phytohormones such as zeatin. Extracts of this plant have demonstrated antioxidant, antimicrobial, and growth-promoting effects. Although Moringa extracts have been used as foliar fertilizers and biostimulants, their efficacy is often temporary due to the rapid degradation of the active ingredients under field conditions. The integration of Moringa phytochemicals into nanoparticle synthesis processes has been described for certain metallic systems; however, such approaches rarely combine the extract simultaneously as a reducing agent, stabilizer, and biofunctionalizing agent in a chitosan-based polymer matrix specifically designed for agricultural micronutrient delivery.

[0013] Another limitation of existing solutions lies in their lack of multifunctionality. Conventional fertilizers primarily address nutrient deficiencies without modulating the plants' immune defenses or stress tolerance. Biostimulants increase metabolic activity but do not provide essential micronutrients in a controlled manner. Chemically synthesized nanoparticles enable improved nutrient supply but may not be biodegradable or environmentally friendly. Chitosan-based products stimulate defense mechanisms but do not naturally provide copper or other micronutrients unless these are added externally. Therefore, farmers often apply several inputs separately, increasing costs, labor, and environmental impact.

[0014] Environmental considerations underscore the need for improved systems. The chemical synthesis of nanoparticles is associated with significant energy consumption and generates wastewater that requires disposal. Overdosing on copper salts can lead to soil accumulation, harm beneficial microorganisms, and potentially enter waterways via surface runoff. Regulatory bodies are increasingly scrutinizing the use of nanoparticles in agriculture, particularly regarding toxicity, persistence, and ecological impacts. Therefore, the development of a biodegradable, plant-based, and environmentally compatible nanoparticle system that enables controlled nutrient release and biostimulating effects is of paramount importance.

[0015] In summary, existing technologies for agricultural micronutrients and biostimulants suffer from low bioavailability, rapid degradation, environmental impact, limited multifunctionality, and inconsistent field performance. Chemically synthesized nanomaterials pose challenges regarding sustainability and safety, while green-synthesized nanoparticles often lack structural stability and integrated biological functionality. Chitosan-based formulations offer promising bioactivity but require improvements in nutrient integration and control at the nanoscale. These technical shortcomings highlight the need for a green, reproducible, and multifunctional nanoparticle system that delivers controlled copper release while also exhibiting biostimulating and antimicrobial properties to overcome the limitations of currently available solutions. Summary of the invention

[0016] The invention describes a biogenic system for the synthesis of chitosan-copper nanoparticles (CHT-Cu-NPs) by controlled reduction of copper ions with phytochemicals from Moringa oleifera leaf extract and subsequent stabilization in a chitosan polymer matrix. The invention further describes a structurally integrated nanoparticle synthesis device comprising a temperature-controlled reaction chamber, a pH control module, an automated droplet infusion unit, a controlled stirring mechanism, and an integrated colloid stabilization unit. This device is configured to produce nanoparticles with a uniform size distribution and reproducible physicochemical properties.

[0017] The present invention aims to provide an environmentally friendly and sustainable system for the biogenic synthesis of chitosan-copper nanoparticles. Moringa oleifera leaf extract is used as a natural reducing and stabilizing agent, thus eliminating the need for toxic chemical reducing agents and hazardous stabilizers commonly used in nanoparticle synthesis. The invention aims to develop an environmentally sound system that operates under moderate temperature and pH conditions while ensuring controlled nucleation, uniform particle growth, and a stable colloidal dispersion suitable for agricultural applications.

[0018] A further objective of the invention is to provide chitosan-copper nanoparticles with a controlled particle size distribution, narrow polydispersity index, and stable zeta potential to ensure improved bioavailability and sustained release of copper ions when applied to crops. The invention aims to structurally integrate copper species into a biodegradable chitosan polymer matrix such that the electrostatic interaction between the amino groups of the chitosan and the reduced copper species leads to improved encapsulation efficiency and prevents particle agglomeration. Control of physicochemical parameters such as pH, temperature, reaction time, and dosage rate is intended to ensure the reproducibility and scalability of the nanoparticle synthesis.

[0019] A further objective of the invention is to provide a multifunctional nanoformulation that simultaneously supplies micronutrients, stimulates plant growth, and offers antimicrobial protection. The invention utilizes residual phytochemicals from Moringa oleifera extract to biofunctionalize the nanoparticle surface, thereby imparting antioxidant properties and enhancing physiological responses in plants. This integration aims to overcome the limitations of conventional single fertilizers and biostimulants by providing a composite system that supports plant metabolism, improves stress tolerance, and increases crop yields.

[0020] A further objective of the invention is to improve nutrient efficiency in agricultural systems through the controlled and sustainable release of copper ions directly at the point of uptake by plants. The invention aims to minimize leaching losses, precipitation, and phytotoxic accumulation, which are frequently associated with the application of large quantities of copper salts. By reducing the amount of copper required for effective fertilization, the invention seeks to reduce environmental impact, maintain the microbial balance in the soil, and contribute to sustainable farming methods.

[0021] A further objective of the invention is to provide a biodegradable and biocompatible, nanotechnology-based agricultural input that can be integrated into organic and precision farming systems. The invention aims to reduce dependence on synthetic chemical fertilizers, growth regulators, and fungicides by providing a nanoformulation that promotes root development, stimulates enzymatic antioxidant systems, and supports plant defense mechanisms against fungal pathogens. This approach is intended to reconcile agricultural productivity with environmental safety and regulatory compliance.

[0022] A further objective of the invention is to provide a structurally integrated nanoparticle synthesis device for the controlled, contamination-free, and reproducible production of chitosan-copper nanoparticles. The invention aims to integrate precise temperature control, automatic pH adjustment, controlled reagent dosing, and uniform stirring into a single reactor to ensure consistent particle properties across different batches. By enabling semi-commercial production with minimized energy consumption and reduced operational complexity, the invention is intended to facilitate the industrial transfer of the biogenic synthesis process.

[0023] The invention also aims to provide a stable nanobiostimulant formulation in an aqueous carrier medium, suitable for foliar or soil application at optimized concentrations. The invention is designed to ensure extended storage stability, minimal sedimentation, and the preservation of colloidal integrity during storage and transport. Improved dispersion properties and increased leaf adhesion are intended to maximize nutrient uptake and physiological effects.

[0024] A further objective of the invention is the development of a nanoparticle system whose agronomic performance has been validated under field conditions and in various environmental environments. The invention aims to achieve improved plant growth parameters, increased chlorophyll content, enhanced enzyme activity, improved root nodule formation, and higher yield characteristics compared to conventional micronutrient or biostimulant treatments.

[0025] Ultimately, the invention aims to provide a technically advanced, environmentally friendly, multifunctional and commercially scalable solution for improving agricultural productivity while minimizing environmental impacts, thereby overcoming the critical limitations of existing micronutrient formulations, synthetic biostimulants and chemically synthesized nanoparticle systems. BRIEF DESCRIPTION OF THE IMAGE

[0026] These and other features, aspects and advantages of the present invention will be better understood if the following detailed description is read with reference to the accompanying drawing, in which the same symbols represent the same parts: Fig. Figure 1 shows a block diagram of a biogenic nanoparticle synthesis system for the production of chitosan-copper nanoparticles using plant extract.

[0027] Furthermore, those skilled in the art will recognize that the elements in the drawing are simplified and not necessarily drawn to scale. For example, the flowcharts illustrate the process by highlighting the main steps to facilitate understanding of the present disclosure. With regard to the construction of the device, one or more components may be represented in the drawing by conventional symbols. The drawing may show only those specific details relevant to understanding the embodiments of the present disclosure, so as not to clutter the drawing with details that are already apparent to those skilled in the art from the description contained herein. Detailed description of the invention

[0028] To facilitate understanding of the principles of the invention, reference is made below to the embodiment shown in the drawing, which is described using specific terms. It is understood, however, that this does not limit the scope of protection of the invention. Rather, modifications and further developments of the depicted system, as well as further applications of the inventive principles shown therein, are conceivable, insofar as they would normally occur to a person skilled in the art in the field of the invention.

[0029] It will be clear to those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not to be understood as a limitation of it.

[0030] References to “an aspect”, “another aspect”, or similar phrases in this description mean that a particular feature, structure, or property described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, phrases such as “in one embodiment”, “in another embodiment”, and similar expressions in this description may, but do not necessarily, all refer to the same embodiment.

[0031] The terms "includes," "comprehensive," or similar expressions denote non-exclusive inclusion. Thus, a procedure or method containing a list of steps does not only include those steps but may also include further steps not explicitly listed or inherent in the procedure or method. Likewise, the statement "includes..." for one or more devices, subsystems, elements, structures, or components, without further limitations, does not preclude the existence of other devices, subsystems, elements, structures, or components.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meanings generally known to those skilled in the art in the field to which this invention belongs. The systems, methods, and examples described herein serve only for illustration and are not to be understood as limiting.

[0033] Embodiments of the present disclosure are described in detail below with reference to the attached drawing.

[0034] Fig.Figure 1 shows a block diagram of a biogenic nanoparticle synthesis system for the production of chitosan-copper nanoparticles using plant extract.System 100 comprises: a closed reaction vessel (102) made of corrosion-resistant material with an internal reaction chamber containing an aqueous copper salt solution and a plant extract mixture; a temperature control unit (104) thermally coupled to the reaction vessel, maintaining the temperature in the internal reaction chamber within a predetermined range of 25 °C to 75 °C with a tolerance of ± 1 °C; a stirring unit (106) with a variable-speed motor and a stirring shaft extending into the internal reaction chamber, ensuring uniform mixing at speeds between 100 and 1000 revolutions per minute; and a plant extract feed unit (108) with a metered inlet tube and a flow control valve for the controlled supply of an aqueous extract from Moringa oleifera leaves into the reaction chamber to initiate the reduction of copper ions.A chitosan solution dosing unit (110) with a programmable peristaltic pump connected to a reservoir containing a chitosan solution dissolved in dilute acetic acid, wherein the dosing unit dispenses the chitosan solution dropwise in a controlled manner into the reaction chamber; a pH monitoring unit (112) with a pH probe extending into the reaction chamber and connected to a control unit; a base addition unit (114) with a reagent container containing sodium hydroxide solution and a precision dosing pump controlled by the control unit to maintain a pH of 6 + 0 for the reaction mixture.5; and a control unit (116) connected to the temperature control unit, the stirring unit, the plant extract feeding unit, the chitosan solution dosing unit, the pH monitoring unit and the base addition unit, synchronizing the temperature control, the reagent addition rate, the stirring speed and the pH correction to produce a stable colloidal suspension of chitosan copper nanoparticles.

[0035] In one embodiment, the reaction vessel (102) comprises a double-walled cylindrical body that defines an inner reaction chamber and an outer annular chamber for the circulation of a heat transfer fluid. The temperature control unit includes a circulating heater and a temperature sensor configured to enable closed-loop thermal control.

[0036] In one embodiment, the stirring unit (106) further comprises a stainless steel stirring wheel with an inclined blade configuration designed to generate an axial flow and minimize vortex formation, thereby preventing the aggregation of nanoparticles during the nucleation and growth phases.

[0037] In one embodiment, the plant extract introduction unit (108) comprises a pre-filtration arrangement with a microporous membrane filter located upstream of the metered inlet line to remove suspended particles prior to introduction into the reaction chamber.

[0038] In one embodiment, the chitosan solution dosing unit (110) is configured to dispense the chitosan solution at a rate between zero one milliliter per minute and five milliliters per minute, thereby enabling controlled encapsulation of reduced copper species in a polymer matrix.

[0039] In one embodiment, the pH monitoring unit (112) comprises a digital probe with automatic temperature compensation capability, wherein the control unit performs feedback control that actuates the base addition unit in incremental microvolumes to prevent overshooting beyond the defined pH range.

[0040] In one embodiment, this further comprises an ultrasonic dispersion unit coupled to the reaction vessel and configured to emit acoustic energy at frequencies between twenty kilohertz and forty kilohertz to reduce particle agglomeration and refine the particle size distribution.

[0041] In an embodiment further comprising a colloid stabilization and collection unit connected to a lower outlet of the reaction vessel, wherein the collection unit comprises a sterile storage reservoir and a low-shear transfer pump configured to transport the synthesized nanoparticle suspension without altering the particle morphology.

[0042] In an embodiment further comprising an inline particle size monitoring unit containing a dynamic light scattering sensor operationally linked to the control unit, wherein the control unit adjusts the stirring speed and temperature parameters based on real-time particle size measurements to maintain a mean hydrodynamic diameter between one hundred forty nanometers and three hundred twenty nanometers.

[0043] In one embodiment, the control unit (116) comprises a programmable logic controller with a memory in which predetermined reaction profiles are stored, including the temperature ramp sequence, the duration of extract addition, the chitosan infusion plan and the stabilization time after the reaction.

[0044] The present invention relates to a biogenic nanoparticle synthesis system for the production of chitosan-copper nanoparticles by means of a precisely controlled reaction sequence regulated by a control unit. The system integrates temperature control, controlled reagent dosing, pH stabilization, stirring control, and optional acoustic dispersion in a closed reaction architecture to ensure reproducibility, a narrow particle size distribution, and colloidal stability. The operation of the system is controlled by a control unit that executes stored control technology and coordinates all mechanical and chemical parameters in a closed control loop.

[0045] At the start of operation, the control unit initiates a pre-reaction validation sequence. This involves performing sensor diagnostics to confirm the functionality of the temperature sensor, pH probe, stirrer motor feedback sensor, and dosing pump calibration sensors. The control unit verifies that the reaction vessel is tightly sealed and the sterile air filter paths are unobstructed. After successful validation, the control unit activates temperature control to set the internal reaction chamber to a predefined initial temperature between 25 °C and 35 °C. This temperature range was chosen to enable optimal phytochemically mediated reduction of copper ions while simultaneously preventing premature polymerization.

[0046] Simultaneously, the stirring unit is activated at a programmed speed between 100 and 400 revolutions per minute to ensure a homogeneous distribution of the aqueous copper salt solution in the reaction chamber. The system continuously monitors the motor torque to detect viscosity changes that could indicate insufficient mixing or concentration gradients. Once temperature equilibrium is reached and stable stirring is confirmed, the control unit activates the feed unit for the plant extract.

[0047] The plant extract is added using a timed infusion technique. The control unit regulates the metered flow to deliver the Moringa oleifera leaf extract at a predefined flow rate for a set duration, typically between twenty and forty minutes. During this phase, the control unit continuously measures temperature and stirring stability and, if an optional optical sensor is installed, monitors changes in optical density to detect the onset of copper ion reduction. The reduction reaction is characterized by a gradual color change in the chamber, which can be detected either visually through the viewing window or with an integrated photometric sensor.

[0048] After confirmation that the reduction process has begun, the control unit switches to pH stabilization mode. The pH monitoring unit continuously transmits real-time pH values ​​to the control unit. As soon as a deviation from the target pH of 0.5 L / 6 is detected, the control unit calculates the required microvolume of base solution for correction. The base is added in incremental pulses to prevent overshoot. The system uses PI control, where the correction value is dynamically adjusted to the pH change rate. This ensures a stable and gradual adjustment instead of abrupt fluctuations.

[0049] After stabilizing the pH and completing the reduction phase, the control unit increases the temperature of the reaction chamber to a second programmed setpoint between 65 °C and 75 °C. This temperature increase is gradual to avoid a temperature shock that could destabilize the emerging nanoparticle cores. Simultaneously, the stirring speed is increased to 400 to 800 revolutions per minute to ensure uniform dispersion during polymer encapsulation.

[0050] The dosing unit for the chitosan solution is then activated by dropwise infusion. The control unit regulates the peristaltic pump to deliver the chitosan solution at a controlled rate between 0.1 and 5 ml / min. The infusion rate is adjusted based on viscosity and optional particle size measurements. The system ensures that the polymer addition is synchronized with the stirring intensity to promote the electrostatic interaction between protonated amino groups of the chitosan and reduced copper species. The stepwise infusion prevents local supersaturation and uncontrolled agglomeration.

[0051] During this encapsulation phase, the control unit continuously evaluates reaction stability parameters such as temperature deviation, stirring torque, and pH drift. If the control unit features particle size monitoring via a dynamic light scattering sensor, it periodically measures the hydrodynamic diameter. If the mean particle size exceeds a programmed threshold, the control unit can temporarily increase the stirring speed or activate the ultrasonic dispersion unit to supply acoustic energy in the frequency range between 20 and 40 kilohertz. This acoustic intervention reduces agglomeration by breaking weak interactions between the particles without damaging the polymer matrix.

[0052] The stabilization phase is programmed to last two to four hours. During this time, the control unit regulates the entire process, adjusting heat input, stirring speed, and microdosing as needed to ensure a uniform reaction. Once the reaction time has elapsed, the control unit initiates a controlled cooling sequence in which the circulation of the heat transfer fluid is gradually reduced to cool the reaction mixture to ambient temperature while gently stirring. This cooling system prevents sudden aggregation caused by contraction.

[0053] After temperature normalization, the control unit deactivates the agitator and opens the lower outlet valve in a controlled manner to transfer the colloidal suspension into the stabilization and collection unit. The transfer pump operates at low shear force to preserve the nanoparticle morphology. Once the downstream filtration is activated, the suspension passes through a membrane filter with a pore size selected to remove macroscopic impurities while allowing nanoparticles to pass through.

[0054] The control unit stores all process parameters, including temperature profile, pH correction intervals, infusion rates, changes in stirring speed, and optional particle size measurements, in its internal memory to ensure batch traceability and reproducibility. These stored data sets enable the optimization of future synthesis cycles and serve as quality assurance tools.

[0055] The control system also includes safety interlocks. If the temperature exceeds a permissible maximum value, the heating system switches off automatically. If the pH value deviates outside the permissible range and cannot be corrected within predefined correction attempts, the system switches to standby mode. An overload detection system for the agitator motor triggers an automatic shutdown to prevent mechanical damage.

[0056] Through the coordinated execution of reduction, pH stabilization, polymer encapsulation, dispersion optimization, and controlled cooling, the system ensures the formation of chitosan-copper nanoparticles with a uniform hydrodynamic diameter, low polydispersity, stable surface charge, and homogeneous dispersion. The integration of real-time sensors and controller-based regulation distinguishes the system from conventional batch reactors that rely on manual parameter settings.

[0057] The Moringa extract is gradually added to the copper sulfate solution under controlled stirring at a temperature of 25-35 °C over a period of 20-40 minutes to initiate the bioreduction of Cu 2+to introduce -ions. The phytochemicals act as electron donors, reduce copper ions, and simultaneously stabilize the formed nucleation nuclei. The pH of the reaction mixture is adjusted to 6.0 ± 0.5 by the controlled addition of 0.6 M sodium hydroxide solution to promote optimal nucleation and prevent uncontrolled precipitation.

[0058] The prepared chitosan solution is then added dropwise to the reaction mixture over 2-4 hours while continuously stirring and maintaining a reaction temperature of 65-75 °C. During this process, an electrostatic interaction occurs between the protonated amino groups (-NH2) of the chitosan and reduced copper species, leading to the encapsulation and stabilization of the copper nanoparticles within a polymeric chitosan matrix. The reaction yields a light blue colloidal suspension, indicating the incorporation of copper on a nanoscale.

[0059] The synthesized nanoparticles exhibit a mean hydrodynamic diameter in the range of 140–320 nm (measured by dynamic light scattering), a morphological size of 140–275 nm (confirmed by transmission electron microscopy), a polydispersity index below 0.30, indicating high homogeneity, and a zeta potential between -10 mV and -20 mV, ensuring colloidal stability. X-ray diffraction analysis confirms crystalline CuO phases embedded in the amorphous chitosan structure, while FTIR spectra reveal characteristic -NH₂, -OH, and Cu₂O bond vibrations, thus confirming successful complexation.

[0060] The nanoparticles have a copper content of between 15 and 25 wt% and a chitosan content of between 30 and 40 wt%, as confirmed by energy-dispersive X-ray spectroscopy. Residual Moringa phytochemicals remain bound to the surface, giving the particles antioxidant and antimicrobial properties, thus fulfilling a dual function as nutrient carriers and biostimulants.

[0061] The invention further relates to a specific machine structure, a so-called biogenic nanoparticle synthesis reactor, configured for the controlled production of chitosan-copper nanoparticles. The device comprises a cylindrical, double-walled reaction chamber made of stainless steel, mounted on a vibration-damped frame. The double wall allows the circulation of thermostatically controlled water or oil to maintain the reaction temperatures constant with an accuracy of +1 °C.

[0062] The reactor chamber contains a top-mounted, variable-speed mechanical stirrer with a corrosion-resistant impeller blade, ensuring uniform mixing without excessive shear forces. A programmable peristaltic pump is mounted above the chamber, enabling the precise, dropwise addition of chitosan solution to the reaction mixture. The instrument also includes a digital pH probe connected to an automated titration module. This module adds sodium hydroxide solution in microaliquots to maintain the pH within predefined limits.

[0063] An integrated control panel houses a microcontroller-based system for synchronizing temperature control, stirring speed, dosing rate, and pH correction. A sealed viewing window made of chemical-resistant borosilicate glass allows for visual monitoring of colloid formation. The lower part of the chamber contains a controlled outlet valve connected to a colloid stabilization and collection unit. This unit is equipped with filtration and a sterile storage container. Optionally, the device can be equipped with an ultrasonic homogenizer to refine the particle dispersion and ensure a narrow particle size distribution.

[0064] The structural integration of temperature control, automated dosing and pH stabilization ensures reproducibility, scalability and contamination-free synthesis, thus enabling semi-commercial production suitable for agricultural input manufacturers.

[0065] The synthesized nanoparticles are dispersed in an aqueous carrier medium to produce a stable colloidal spray formulation with an active ingredient concentration of 50-600 ppm. This formulation results in a sustained release of copper ions, improved uptake via the leaves, increased activation of plant metabolism, stimulation of root nodule formation, enhanced activity of antioxidant enzymes, and protection against fungal infections.

[0066] The invention offers an environmentally friendly synthesis pathway that eliminates the need for toxic chemical reducing agents and energy-intensive processes. The nanoparticles exhibit multifunctionality, simultaneously delivering micronutrients, activating plant defenses, and stimulating phytohormone production. Controlled nanodimensions ensure improved bioavailability and delayed release compared to conventional copper preparations. The phytochemicals derived from Moringa impart additional antioxidant and antimicrobial properties not found in conventional chitosan-metal systems. The specially designed reactor device enhances scalability, reproducibility, and commercial feasibility.

[0067] In contrast to previously described chemically synthesized chitosan-metal nanocomposites or pure copper nanoparticles, the present invention uniquely integrates biogenic reduction using phytochemicals from Moringa oleifera with chitosan-based encapsulation in a single controlled process. Prior art lacks simultaneous biofunctionalization, tight particle size control under environmentally friendly synthesis conditions, and integrated reactor design. Furthermore, the invention demonstrates field-proven multifunctional agronomic benefits by combining nutrient delivery and biostimulation in a single nanoformulation.

[0068] The invention is industrially applicable in the fields of sustainable agriculture, precision agriculture, organic farming, micronutrient formulations, nanotechnology-based crop protection, and environmentally friendly production of agricultural inputs. The integrated synthesis device enables the transfer of laboratory results to a commercial scale while complying with environmental regulations.

[0069] The drawing and the preceding description illustrate embodiments. Those skilled in the art will recognize that one or more of the described elements can be combined to form a single functional element. Alternatively, certain elements can be divided into several functional elements. Elements of one embodiment can be added to another. For example, the process flows described here can be modified and are not limited to the manner described herein. Furthermore, the actions of a flowchart need not be performed in the sequence shown; nor do all actions necessarily need to be carried out. Actions that do not depend on other actions can be performed in parallel with the other actions. The scope of protection of the embodiments is in no way limited by these specific examples. Numerous variations, whether explicitly stated in the description or not, such as...Differences in structure, dimensions, and materials are possible. The scope of protection of the embodiments is at least as comprehensive as described by the following claims.

[0070] The advantages, other benefits, and problem solutions have been described above with reference to specific embodiments. However, the advantages, benefits, problem solutions, and any components that can effect or enhance an advantage, benefit, or solution are not to be construed as critical, necessary, or essential features or components of the claims. REFERENCE 100 A System for the Synthesis of Biogenic Nanoparticles for the Production of Chitosan-Copper Nanoparticles Using Plant Extracts. 102 Sealed reaction vessel 104 Temperature control unit 106 Stirrer 108 Plant Extract Introductory Unit 110 Chitosan solution dosing unit 112 pH monitoring unit 114 Basic addition unit 116 Control unit

Claims

[1] A biogenic nanoparticle synthesis system for the production of chitosan-copper nanoparticles using plant extract, the system comprising: a sealed reaction vessel made of corrosion-resistant material, forming an inner reaction chamber configured to contain an aqueous copper salt solution and a plant extract mixture; a temperature control unit that is thermally coupled to the reaction vessel and configured to maintain the temperature inside the reaction chamber within a predetermined range between 25 degrees Celsius and 75 degrees Celsius with a tolerance of plus / minus one degree Celsius; a stirring unit consisting of a variable speed motor and a stirring shaft extending into the inner reaction chamber, wherein the stirring unit is configured to ensure uniform mixing at speeds between one hundred and one thousand revolutions per minute; a plant extract introduction unit consisting of a metered inlet line and a flow control valve configured to introduce an aqueous extract from Moringa oleifera leaves into the reaction chamber at a controlled rate to initiate the reduction of copper ions; a dosing unit for chitosan solution, consisting of a programmable peristaltic pump connected to a reservoir containing a chitosan solution dissolved in dilute acetic acid, wherein the dosing unit is configured to dispense the chitosan solution in a controlled dropwise manner into the reaction chamber; a pH monitoring unit with a pH probe protruding into the reaction chamber; a base addition unit consisting of a reagent reservoir with sodium hydroxide solution and a precision dosing pump to maintain a pH value of the reaction mixture of six plus / minus zero point five; a control unit that is operationally connected to the temperature control unit, the stirring unit, the plant extract feeding unit, the chitosan solution dosing unit, the pH monitoring unit and the base addition unit, wherein the control unit is configured to synchronize the temperature control, the reagent addition rate, the stirring speed and the pH correction to produce a stable colloidal suspension of chitosan copper nanoparticles. [2] System according to claim 1, wherein the reaction vessel comprises a double-walled cylindrical body defining an inner reaction chamber and an outer annular chamber for circulating a heat transfer fluid, wherein the temperature control unit comprises a circulating heater and a temperature sensor configured to provide closed thermal control. [3] System according to claim 1, wherein the stirring unit further comprises a stainless steel stirring wheel with an inclined blade configuration designed to generate an axial flow and minimize vortex formation, thereby preventing the aggregation of nanoparticles during the nucleation and growth phases. [4] System according to claim 1, wherein the plant extract introduction unit comprises a pre-filtration arrangement consisting of a microporous membrane filter arranged upstream of the metered inlet line to remove suspended particles prior to introduction into the reaction chamber. [5] System according to claim 1, wherein the chitosan solution dosing unit is configured to dispense the chitosan solution at a rate between zero one milliliter per minute and five milliliters per minute, thereby enabling controlled encapsulation of reduced copper species in a polymer matrix. [6] System according to claim 1, wherein the pH monitoring unit comprises a digital probe with automatic temperature compensation capability and wherein the control unit performs a feedback control which actuates the base addition unit in incremental microvolumes to prevent overshooting beyond the defined pH range. [7] System according to claim 1, further comprising an ultrasonic dispersion unit coupled to the reaction vessel and configured to emit acoustic energy at frequencies between twenty kilohertz and forty kilohertz to reduce particle agglomeration and refine the particle size distribution. [8] The system according to claim 1 further comprises a colloid stabilization and collection unit connected to a lower outlet of the reaction vessel, the collection unit comprising a sterile storage reservoir and a low-shear transfer pump configured to transport the synthesized nanoparticle suspension without altering the particle morphology. [9] System according to claim 1, further comprising an inline particle size monitoring unit with a dynamic light scattering sensor connected to the control unit, wherein the control unit adjusts the stirring speed and temperature parameters based on real-time particle size measurements to maintain a mean hydrodynamic diameter between one hundred forty nanometers and three hundred twenty nanometers. [10] System according to claim 1, wherein the control unit comprises a programmable logic controller with a memory in which predetermined reaction profiles including temperature ramp sequence, extract addition duration, chitosan infusion plan and stabilization time after the reaction are stored.

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