Visible-light-driven antibacterial agent, preparation thereof and application of visible-light-driven antibacterial agent in plant disease control

Abstract

The invention relates to the technical field of agricultural antibacterial agents and plant disease control, in particular to a visible-light-driven antibacterial agent, preparation of the visible-light-driven antibacterial agent and application of the visible-light-driven antibacterial agent in plant disease control. The visible light driven antibacterial agent comprises the following components in parts by mass: 85-99 parts of a composite dispersion carrier with temperature-sensitive and light-responsive properties; 0.5 to 5 parts of a composite surfactant; 0.3-2 parts of a targeted leaf surface affinity agent; 0.5-3 parts of a multi-stage penetrant; 0.05 to 0.3 part of a biological synergist; 0.05 to 1 part of a pH regulator; and a red light carbon dot photosensitizer; wherein the concentration of a red light carbon dot photosensitizer in the visible light driven antibacterial agent is 50-200 mg / L. Through the synergistic effect of the composite dispersion carrier and each auxiliary agent, the red light carbon dot photosensitizer gives full play to the killing effect, efficient inactivation of plant pathogens such as fungi, bacteria and viruses is realized, and meanwhile, the stability and environment resistance of the antibacterial agent and the crop gain effect are improved.

Description

Technical Field

[0001] This invention relates to the field of agricultural antibacterial agents and plant disease control technology, specifically including a visible light-driven antibacterial agent, its preparation, and its application in plant disease control. Background Technology

[0002] Pathogenic microorganisms such as fungi, bacteria, and viruses are among the most common and harmful biological factors in crop production. Fungi, such as gray mold, powdery mildew fungi, and so on, can infect leaves, stems, and fruits, leading to tissue necrosis, fruit drop, and reduced quality. Bacteria, such as Xanthomonas spp. and Pseudomonas syringae, can cause leaf spots, cankers, and wilt, and in severe cases, can cause the death of the entire plant. Viruses, such as tobacco mosaic virus and cucumber mosaic virus, often cause mottled and deformed leaves, affecting photosynthesis and thus inhibiting plant growth and yield. These diseases not only increase in incidence in greenhouses and fields with increasing crop planting density, but also spread rapidly during post-harvest storage and transportation, causing huge losses to agricultural production.

[0003] Currently, farmers mainly rely on chemical pesticides to control pathogenic microorganisms, including synthetic organic fungicides (such as benzimidazoles and dithiocarbamates), metal ion preparations (such as copper sulfate and copper hydroxide), and certain biopesticides. However, these traditional control methods generally have the following drawbacks: First, high-frequency and long-term use easily leads to the development of drug resistance in pathogenic strains, causing the dosage and frequency of pesticide application to continuously increase; second, pesticide residues in soil, water bodies, fruit and vegetable surfaces, and the environment may harm non-target organisms and even affect human and animal health through the food chain; third, under climatic conditions such as strong light, rain, or high temperatures, the chemical structure of some organic antibacterial agents is easily damaged, resulting in rapid deterioration and short duration of action; fourth, conventional spraying methods do not provide sufficient contact with the crop surface, and the protective effect is greatly reduced in rainy or low-light conditions in greenhouses.

[0004] Photodynamic pest control (PDP) technology uses photosensitizers to release ground-state oxygen (…) under irradiation with a suitable wavelength of light. 3 O2) is converted into singlet oxygen ( 1 O2) or generated through electron transfer. - Reactive oxygen species (ROS) such as ·OH can oxidize and destroy the cell membranes, proteins, and nucleic acids of pathogens, achieving highly efficient killing without easily inducing drug resistance. This mechanism has advantages such as "no pesticide residue," "broad-spectrum antibacterial," "environmentally friendly," and "reversible control." Currently, PDP technology has some applications in medical disinfection and wastewater treatment, but research on the prevention and control of agricultural diseases, especially plant pathogenic fungi, bacteria, and viruses, is still in the exploratory stage. Furthermore, existing agricultural PDP-related technologies face the following key issues that urgently need to be addressed: 1) Single function of dispersing carrier: Existing technologies mostly use water or simple water-based media as carriers, which only serve to dissolve photosensitizers. As a result, photosensitizers are easily washed away by rainwater or irrigation water after spraying, or volatilized due to leaf transpiration, resulting in extremely low utilization (usually less than 50%). 2) Poor synergistic effect of adjuvants: Most existing adjuvants are single-function (such as single surfactants or single affinity agents), which cannot achieve synergistic effects such as dispersion stability, targeted enrichment, penetration and bactericidal enhancement. This makes it difficult for photosensitizers to act accurately on pathogens, thus limiting the bactericidal effect. 3) Weak resistance to environmental interference: In complex environments such as rain, high humidity, and strong light, photosensitizers are easily lost or photodegraded (photobleaching), resulting in a short protection duration (usually requiring repeated application after 7-14 days) and poor compatibility; 4) Single bactericidal mechanism: It relies solely on the oxidizing effect of ROS, which has limited effect on controlling highly resistant strains that have been exposed to pesticides for a long time, and there is still a risk of resistance with long-term use; 5) Functional limitations: It can only inactivate diseases and cannot promote crop growth. Crop growth is easily inhibited after disease stress, making it difficult to meet the dual needs of "disease prevention + yield increase" in agricultural production.

[0005] To achieve the large-scale promotion and application of agricultural PDP technology, it is urgent to develop a new type of antibacterial agent based on existing high-efficiency red light carbon point photosensitizers, and through innovative dispersion carrier and adjuvant systems, to solve the core pain points such as "loss, inefficiency, instability, and singleness". This is also a technical bottleneck that needs to be overcome in the field of agricultural photodynamic pest control. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, such as single-function dispersion carriers, poor synergistic effects of adjuvants, low utilization rate of photosensitizers, weak resistance to environmental interference, functional limitations, and insufficient adaptability to various scenarios, the first objective of this invention is to provide a visible light-driven antibacterial agent. Without altering the fundamental properties of red-light carbon dot photosensitizers, through the innovative design of a composite dispersion carrier and a multifunctional synergistic adjuvant system, highly efficient inactivation of plant pathogens such as fungi, bacteria, and viruses is achieved, while simultaneously improving the stability, environmental resistance, and crop benefit of the antibacterial agent.

[0007] A second objective of this invention is to provide a method for preparing the visible light-driven antibacterial agent as described above.

[0008] A third objective of this invention is to provide an application of the visible light-driven antibacterial agent described above in the prevention and control of plant diseases.

[0009] To achieve the first objective mentioned above, the present invention adopts the following technical solution: This invention discloses a visible light-driven antibacterial agent, comprising, by weight parts: 85-99 parts of a composite dispersion carrier with temperature- and light-responsive properties; 0.5-5 parts of compound surfactant; Targeted leaf affinity agent 0.3-2 parts; Multi-stage penetrant 0.5-3 parts; Biological synergist 0.05-0.3 parts; pH adjuster 0.05-1 part; and Red-light carbon dot photosensitizer; The concentration of the red carbon dot photosensitizer in the visible light driven antibacterial agent is 50-200 mg / L.

[0010] The core innovation of this invention lies in the use of a composite dispersion carrier with temperature- and light-responsive properties and a multifunctional synergistic adjuvant system to construct an integrated system of "carrier controlled release - adjuvant targeting - photosensitizer high-efficiency action". The multifunctional synergistic adjuvant system includes a composite surfactant, a targeted leaf surface affinity agent, a multi-level penetration agent, a bio-synergist and a pH adjuster. After the antibacterial agent is dispersed in a composite dispersion carrier and sprayed onto the crop surface, the composite dispersion carrier can form a microgel to lock the photosensitizer when the crop surface temperature reaches above the low critical dissolution temperature of the composite dispersion carrier. The multifunctional synergistic adjuvant system achieves targeted enrichment and multi-level penetration of the red light carbon point photosensitizer. After irradiation with visible light, it achieves an inactivation rate of >99.5% against a variety of pathogens, including Botrytis cinerea, Botrytis cinerea, Tomato canker fungus, Xanthomonas cepacia, Fusarium graminearum, Rice blast fungus, Fibroblast fungus, Fusarium wilt fungus, Powdery mildew fungus, Xanthomonas causalus of rapeseed, Pseudomonas syringae, Cassava brown streak virus, Tomato spotted wilt virus, Tobacco mosaic virus, and Cucumber mosaic virus. At the same time, the biocompatible components of the carrier and adjuvant can improve the leaf microenvironment and have a significant beneficial effect on crop growth. This invention breaks through the traditional simple compounding mode of "photosensitizer + single carrier / adjuvant". The preparation process is simple, green and environmentally friendly. It has the advantages of broad spectrum and high efficiency, low drug resistance risk, rain washout resistance, long-term stability and easy large-scale application. It is suitable for greenhouse, field, post-harvest and high humidity complex agricultural scenarios.

[0011] Furthermore, the red carbon dot photosensitizer was prepared according to the method described in Example 3 of patent CN103109867A, and the specific steps are as follows: PT2, where n is an integer between 2 and 3000; A 1M potassium hydroxide aqueous solution was added to the polymer PT2 solid powder and mixed thoroughly. The homogeneous reaction solution was transferred into an ultrasonic reactor and reacted at 240-260℃ for 30-40 hours. After cooling, it was separated and purified to obtain S and N diatomic doped water-soluble carbon quantum dots.

[0012] Furthermore, by mass percentage, the composite dispersion carrier comprises 85-95 wt% water, 1-5 wt% poly(N-isopropylacrylamide) (PNIPAM), and ethylene glycol, with the total mass percentage of water, poly(N-isopropylacrylamide), and ethylene glycol being 100 wt%. The molecular weight of the poly-N-isopropylacrylamide is 2000-20000; The low critical dissolution temperature characteristic of the composite dispersion carrier is due to poly(N-isopropylacrylamide), and the low critical dissolution temperature of the composite dispersion carrier is 28-32℃.

[0013] By utilizing the low critical dissolution temperature (LCST, 28-32℃) of the composite dispersion carrier, a reversible microgel can be formed at crop leaf surface temperature to lock the photosensitizer. That is, when the temperature is below the LCST, the phase is transparent and the hydrogel swells, while when the temperature is above the LCST, phase separation occurs and the hydrogel volume shrinks sharply.

[0014] Furthermore, the composite surfactant is a mixture of tea saponin and alkyl polysaccharide in a mass ratio of 2:3. The alkyl polysaccharide can be a commercially available C12-C14 medium-chain alkyl polysaccharide product (e.g., APG 1214, n=1.2-1.6), which possesses excellent aqueous dispersibility and biocompatibility. When combined with tea saponin, it significantly improves the dispersion stability of the photosensitizer, avoiding the drawback of a single surfactant where "strong dispersibility leads to poor compatibility." The tea saponin has a purity of ≥90%, and can simultaneously improve the aqueous dispersion stability and biocompatibility of the photosensitizer, solving the problem of difficulty in achieving both dispersibility and compatibility with a single surfactant.

[0015] Furthermore, the targeted leaf affinity agent is a mixture of chitosan quaternary ammonium salt and soybean lectin at a mass ratio of 4:1. Soybean lectin can specifically bind to glycoproteins on the surface of pathogen cell membranes, enabling the photosensitizer to be targeted and enriched at the lesion site, thus solving the problems of random distribution of photosensitizers and insufficient contact with pathogens. Specifically, the molecular weight of the chitosan raw material used to prepare the chitosan quaternary ammonium salt is limited to 50k-100kDa, and the degree of quaternization substitution DS=0.4-0.6. Corresponding products can be commercially available according to these requirements, such as agricultural quaternized chitosan QCS-60 produced by Shandong Laizhou Haili Biological Products Co., Ltd. This type of chitosan quaternary ammonium salt can balance its water solubility and cationic binding capacity. When synergistically acting with soybean lectin, it can more accurately target and bind to glycoproteins on the surface of pathogen cell membranes, achieving efficient enrichment of the photosensitizer at the lesion site. If the molecular weight of the raw material is too large (>100kDa), it will lead to increased viscosity and uneven spraying; if the substitution is too low (<0.4), the targeting binding force will be insufficient.

[0016] Furthermore, the multi-stage penetrant is a compound of polyethylene glycol 200 and triglycerides in a mass ratio of 1:2.

[0017] Furthermore, the biosynergist is an allicin derivative, such as allicin acetate (chemical structural formula (CH2=CHCH2S)2COCH3), with a purity ≥95%. This allicin derivative has improved stability and lipophilicity through esterification modification, can penetrate the cell membrane of pathogens and inhibit their metabolic enzyme activity, and forms a dual bactericidal mechanism of "oxidative destruction + metabolic blockade" with the reactive oxygen species generated by the red light carbon dot photosensitizer. Compared with unmodified allicin or other etherified derivatives, the control effect on highly resistant strains is improved by 10%-15%.

[0018] Furthermore, the pH adjuster is a citrate-potassium dihydrogen phosphate buffer system, used to adjust the pH of the visible light driven antibacterial agent to 5.5-7.5.

[0019] Furthermore, the visible light-driven antibacterial agent has a pH of 5.5-7.5, and its state changes reversibly with ambient temperature: when the temperature is <28℃ (below the low critical dissolution temperature of the composite dispersion carrier), it is a homogeneous transparent liquid, which is convenient for spray application; when the temperature is ≥28℃ (reaching or exceeding the low critical dissolution temperature of the composite dispersion carrier), the composite dispersion carrier undergoes phase separation to form a reversible microgel, locking the photosensitizer on the crop surface and preventing rainwater erosion or evaporation loss.

[0020] To achieve the second objective mentioned above, the present invention adopts the following technical solution: This invention discloses a method for preparing the visible light-driven antibacterial agent as described above, comprising the following steps: Add the composite surfactant, targeted leaf affinity agent, multi-stage penetration agent, bio-enhancing agent and pH adjuster to the composite dispersion carrier according to the formula amount, stir and disperse, then add red light carbon dot photosensitizer, and disperse by ultrasonication to obtain the final product.

[0021] Furthermore, the stirring and dispersion time is 20-60 minutes.

[0022] Furthermore, the ultrasonic dispersion time is 20-60 minutes, and the power is 300W.

[0023] To achieve the third objective mentioned above, the present invention adopts the following technical solution: This invention discloses an operation method for controlling plant diseases, which involves uniformly spraying the visible light-driven antibacterial agent as described above onto the surface of crops (e.g., the surface of plant leaves or fruits); wherein the spraying amount of the visible light-driven antibacterial agent is 1-3 mL / plant. When the temperature on the crop surface rises to above 28°C, the composite dispersion carrier in the visible light-driven antibacterial agent can form a microgel that locks the red light carbon dot photosensitizer. Under visible light irradiation, the red light carbon dot photosensitizer can kill plant pathogens under the synergistic effect of the targeted leaf affinity agent and the multi-level penetration agent.

[0024] Furthermore, the visible light originates from sunlight, a xenon lamp, or a portable LED handheld light; The intensity of the visible light is 10-100 mW / cm². 2 The total irradiation time for a single session is 10-25 minutes, using either continuous or intermittent irradiation. Each continuous irradiation session lasts 5-10 minutes, followed by a 1-2 minute interval before irradiation again, with a total cumulative duration of 10-25 minutes. Both continuous and intermittent irradiation can achieve efficient inactivation of pathogens.

[0025] In environments with high humidity (RH≥85%) or high incidence of diseases, the application cycle can be adjusted to 8 days. In normal environments, the application cycle is 10-15 days. This method is suitable for various complex scenarios such as greenhouses, open fields, post-harvest areas, and rainy regions.

[0026] Furthermore, the plant pathogen is selected from one or more of the following: Botrytis cinerea, Grape downy mildew, Tomato canker fungus, Xanthomonas scabra, Fusarium graminearum, Rice blast fungus, Canker fungus, Banana wilt fungus, Powdery mildew fungus, Xanthomonas scabra, Pseudomonas syringae, Cassava brown streak virus, Tomato spotted wilt virus, Tobacco mosaic virus, and Cucumber mosaic virus.

[0027] The beneficial effects of this invention are as follows: 1. Solving the problems of photosensitizer loss and low utilization rate: The thermo- and light-responsive composite dispersion carrier forms a microgel at crop leaf temperature, firmly locking the photosensitizer at the action site, improving rain washout resistance by more than 40%, and the antibacterial rate still reaches 98.5% after washing; the targeted leaf affinity agent enables photosensitizer to be directionally enriched on the surface of pathogens, improving the utilization rate by more than 50% compared with traditional formulas, completely solving the industry pain point of "waste of effective ingredients"; 2. Solving the problems of single function and poor synergy of adjuvants: The multifunctional synergistic adjuvant system realizes the four-in-one function of "dispersion and stability - targeted enrichment - multi-level penetration - synergistic bactericidal". Among them, the compound surfactant takes into account both dispersibility and biocompatibility, avoiding the irritation risk of single surfactants. The targeted affinity agent and the multi-level penetrant work together to solve the problem of "insufficient contact and difficult penetration" of photosensitizers. The bio-synergist and active oxygen form a dual bactericidal mechanism, which improves the control effect of highly resistant strains by more than 10%. 3. Solving the problems of weak resistance to environmental interference and short duration of protection: The physical protection of the composite dispersion carrier and the stabilizing effect of the composite surfactant enable the antibacterial agent to be stably stored for more than 8 months at 4-50℃, and the photodegradation rate of photosensitizer is reduced by 35%; the continuous protection period is extended to 10-15 days (8 days under high humidity environment), which is 6-8 days longer than the traditional formula, reducing the number of repeated applications and reducing the cost of use for farmers; 4. Addressing the risks of drug resistance and insufficient bactericidal efficiency: Retaining the multi-mechanism effects of non-target ROS, and adding the metabolic inhibitory effect of a biosynergist, a dual mechanism of "oxidative damage + metabolic blockade" is formed. After 12 consecutive generations of bacterial culture testing, no drug-resistant strains were found. Simultaneously, the photosensitizer's enrichment and penetration effects increase local concentration, raising the inactivation rate from >99% to >99.5%. 5. Solves the problem of single function and no crop benefit: The compound dispersion carrier and the biocompatible components (tea saponin, soybean lectin, allicin derivatives) in each adjuvant have no chemical residues, and can improve the leaf microenvironment, promote stomatal opening and nutrient absorption, stimulate the activity of crop stress-resistant enzymes (SOD, POD), increase crop plant height by 8%-12%, and increase chlorophyll content by 10%, achieving a win-win situation of "disease prevention + growth promotion"; 6. Solves the problem of poor adaptability in complex scenarios: The characteristics of being resistant to rain erosion and stable in high humidity are suitable for rainy areas in the south and high humidity environments in greenhouses; the targeted enrichment effect ensures that the effective concentration of photosensitizer on the surface of pathogens can still be guaranteed in low light environments (such as low light in greenhouses); the formula is compatible with conventional spraying equipment and is suitable for a variety of objects such as leafy vegetables, fruit vegetables, field crops, and post-harvest fruits, achieving full-scene coverage. Attached Figure Description

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] Figure 1 The NMR spectrum of the red carbon dot photosensitizer prepared in Example 1 is shown.

[0030] Figure 2 The absorption spectrum of the red carbon dot photosensitizer prepared in Example 1 is shown.

[0031] Figure 3 The in vitro antibacterial effects of different antimicrobial agents on Botrytis cinerea are shown in Example 2.

[0032] Figure 4 The SEM / TEM observations of different antibacterial agents against Botrytis cinerea in Example 2 are shown.

[0033] Figure 5 The effects of different antibacterial agents in Example 3 on the control of gray mold in greenhouse tomatoes are shown. Detailed Implementation

[0034] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0035] Example 1 Preparation of red carbon dot photosensitizer: The preparation of red carbon dot photosensitizer refers to the method in Example 3 of patent CN103109867A, and the preparation steps are as follows: PT2, where n is an integer between 2 and 3000; 5 mg of polymer PT2 solid powder was placed in a beaker, and 40 mL of 1 M potassium hydroxide aqueous solution was added and mixed thoroughly. The mixed reaction solution was then transferred to an ultrasonic reactor and reacted at 250 °C for 36 hours. After cooling, the mixture was separated and purified to obtain a red carbon dot photosensitizer. The NMR spectrum of the red carbon dot photosensitizer is shown below. Figure 1 .

[0036] Figure 2 The absorption spectrum of the prepared red carbon dot photosensitizer is shown. This red carbon dot photosensitizer has strong absorption in the visible light region around 550 nm, weak absorption in the 350-400 nm range, and no absorption after 650 nm.

[0037] Preparation of composite dispersion carrier: Take 90g water, 5g ethylene glycol and 3g PNIPAM (molecular weight 20000), stir and dissolve at 60℃ for 30min, cool to room temperature to obtain a composite dispersion carrier with thermo- and photo-responsive properties. Its LCST was tested to be 30℃, which is within the range of crop leaf temperature.

[0038] Antibacterial agent preparation: Add 1.5g of a composite surfactant (tea saponin (92% purity) and alkyl polysaccharide glycoside (APG 1214, alkyl chain C12-C14, degree of polymerization 1.4) in a mass ratio of 2:3) to the above composite dispersion carrier, 0.8g of a targeted leaf affinity agent (chitosan quaternary ammonium salt (agricultural quaternized chitosan QCS-60 purchased from Shandong Laizhou Haili Biological Products Co., Ltd.) and soybean lectin in a mass ratio of 4:1), 1.0g of a multi-stage penetration agent (polyethylene glycol 200 and triglycerides in a mass ratio of 1:2), 0.1g of a biosynthetic agent (allicin acetate, 96% purity), and 0.2g of a pH adjuster (citric acid-potassium dihydrogen phosphate buffer), and stir and disperse for 20min; add 0.2g of red carbon dot photosensitizer, and ultrasonically disperse for 30min (300W) to obtain the antibacterial agent. pH The concentration of the red carbon dot photosensitizer is 200 mg / L, with a value of 6.8. It is a homogeneous flowing liquid at 25°C, forms a reversible microgel at 30°C, does not separate into layers when standing, and retains ≥96% stability after 6 months of storage.

[0039] Example 2 Preparation of test strains: The highly resistant Botrytis cinerea strain BC-Res (acclimated by 5 generations of chemical pesticides) was inoculated on PDA plates and cultured at 25±1℃ for 7 days; fresh mycelial blocks were taken from the edge of the colony using a 5mm sterile punch and stored in deionized water at 4℃ for ≤24h for later use. Experimental Groups: Blank group: Water; Control group 1: Traditional formula (containing only red carbon dot photosensitizer PT2 + water + 0.3% single surfactant Tween 20, red carbon dot photosensitizer concentration 200mg / L); Control group 2: Simple compound formulation (red carbon dot photosensitizer PT2 + water + 5% ethylene glycol + 0.3% chitosan quaternary ammonium salt, red carbon dot photosensitizer concentration 200mg / L); This invention group: Antibacterial agent prepared in Example 1 (red light carbon dot photosensitizer concentration 200 mg / L); Antibacterial test: Each formulation was added to PDA medium cooled to 45℃, magnetically stirred for 15 min (350 rpm), and poured into 9 cm petri dishes (25 mL per dish). The dishes were then placed horizontally to cool and solidify. The bacterial blocks were placed face down in the center of the plates and incubated in the dark at 25℃ for 2 h. After incubation, the plates were transferred to a 30℃ incubator (simulating crop leaf temperature to allow the composite dispersion carrier to form microgels). After incubation for another 70 h, the colony diameter (D) was measured, and the antibacterial rate (IR) was calculated using the formula: IR(%) = [(D_blank - D_treatment) / (D_blank - 5)] × 100. The data for D_blank was obtained from the colony diameter of the blank group, and the data for D_treatment was obtained from the colony diameter of control group 1, control group 2, or the group of the present invention.

[0040] Washing resistance simulation test: Each formulation was sprayed onto the surface of a PDA plate (5 mL per plate), placed at 30°C for 1 h (microgels formed in the group of this invention, and the control group dried naturally), rinsed with deionized water (flow rate 5 mL / min, rinse for 30 s), and then the above antibacterial test was performed. result: Figure 3 The in vitro antibacterial effects of different antimicrobial agents on Botrytis cinerea are shown in Example 2.

[0041] Experimental results without flushing simulation test: The antibacterial rate of the invention group reached 99.7%, while that of control group 1 was only 86.5% (highly resistant strains caused a significant decrease in the effectiveness of the traditional formula), and control group 2 was 91.2%; Experimental results of flushing simulation tests: The antibacterial rate of the present invention group still reached 98.5%, while that of control group 1 decreased to 58.3% and that of control group 2 decreased to 72.1%.

[0042] Figure 4 The following is an SEM / TEM observation of the in vitro antibacterial effects of different antimicrobial agents on *Botrytis cinerea* in Example 2. SEM / TEM observation showed that the hyphae of the highly resistant *Botrytis cinerea* in the present invention group were completely ruptured, the cell membrane disintegrated, and organelles dissolved; control group 1 showed only localized damage, while the hyphal structure of control group 2 remained relatively intact. This demonstrates that the "carrier locking + adjuvant synergy + dual bactericidal" system of the present invention effectively solves multiple problems such as the control of highly resistant strains, photosensitizer loss, and insufficient penetration.

[0043] Example 3 Experimental setup: The test crop was tomato (Solanum lycopersicum cv. 'MicroTom'), at the flowering stage of the first inflorescence 50 days after sowing; the experiment was divided into 3 groups, with 30 plants in each group, randomly arranged; the experimental environment simulated a rainy area in southern China (artificial rainfall twice a week, 10 mL / plant each time). Disease inoculation: Prepare 1×10 5Spray a suspension of highly resistant Botrytis cinerea spores / mL (containing 0.01% Tween 20) onto both sides of all leaves (1.5 mL / plant). Treatment process: 24 hours after inoculation, each group was sprayed with the corresponding formula using conventional spraying equipment, with a spraying amount of 2 mL / plant; the formula preparation for control group 1, control group 2, and the group of the present invention was the same as in Example 2; After spraying, the greenhouse environment was 28±2℃ / RH 80±5% (high humidity scenario), and the natural light intensity was 120-250μmol. m -2 ·s -1 PAR, irradiation time is approximately 8 hours per day; Disease assessment and growth index determination: The percentage of leaf lesion area was measured at 7 and 12 days after treatment (ImageJ software analysis) and the control efficiency (CE) was calculated; the tomato plant height and leaf chlorophyll content were measured at 15 days after treatment (SPAD method). result: Figure 5 The effects of different antibacterial agents in Example 3 on the control of gray mold in greenhouse tomatoes are shown.

[0044] Control efficiency: 7 days after treatment, the CE of the present invention group reached 99.6%, while that of control group 1 was 78.5% and control group 2 was 85.3%; 12 days after treatment, the control efficiency of the present invention group remained at 90.1%, while that of control group 1 decreased to 45.7% and control group 2 decreased to 58.9%. Growth indicators: The tomato plant height in the present invention group increased by 11.3% and the chlorophyll content increased by 12.5% ​​compared with the control group 1; there was no significant difference between the control group 2 and the control group 1. Conclusion: The formulation of this invention can maintain a high efficiency and long-lasting control effect in complex field scenarios with high humidity and heavy rainfall, while promoting crop growth, effectively solving the problems of poor adaptability and single function of traditional formulations.

[0045] Example 4 Test system: The pathogen was a highly resistant strain of Pseudomonas syringae pv. tomato DC3000 (ATCC BAA-871-R), and the host plant was a 4-week-old Nicotiana benthamiana. Inoculation method: Leaf cutting method (1×10⁶ bacterial culture) 8 (CFU / mL, 5μL dripped onto the wound); Treatment process: One hour after inoculation, spray the antibacterial agent prepared in Example 1 (red light carbon dot photosensitizer concentration 200 mg / L) at a rate of 1.5 mL / plant; place in a 28℃ artificial climate chamber (RH 60%, 14h light exposure) to allow the composite carrier to form microgels; use an LED array light source (630±5nm, light intensity 25mW / cm²). 2 ) Irradiation for 15 minutes; Control group: Sprayed with a simple compound formula (red carbon dot photosensitizer PT2 + water + 5% ethylene glycol + 0.3% chitosan quaternary ammonium salt, red carbon dot photosensitizer concentration 200 mg / L), with other conditions being the same; Antibacterial efficiency assessment: The lesion area was measured 7 days after treatment, and the inhibition rate was calculated; the enrichment of photosensitizer on the bacterial surface was detected by fluorescent labeling method (FITC-labeled photosensitizer); Results: The inhibition rate of the present invention group against highly resistant Pseudomonas syringae reached 99.5%, which was 16.8% higher than that of the control group. Fluorescence imaging showed that the fluorescence intensity of the photosensitizer on the bacterial surface of the present invention group was 2.7 times higher than that of the control group, proving that the targeted leaf surface affinity agent effectively enhanced the enrichment of photosensitizer on the pathogen surface, and the multi-level permeation agent promoted the penetration of photosensitizer into the bacterial cell membrane, thus synergistically solving the problems of "insufficient contact and difficult penetration".

[0046] Example 5 Virus preparation: The highly resistant strain of tobacco mosaic virus (TMV) (PV-0410-Res) was propagated in Sansi tobacco. The virus extract was quantitatively analyzed by UV spectroscopy with an A260 of 3.5 and diluted to a working concentration of 100 μg / mL (containing 1% diatomaceous earth). Experimental Groups: Control group: Simple compound formulation (red carbon dot photosensitizer PT2 + water + 5% ethylene glycol + 0.3% chitosan quaternary ammonium salt, red carbon dot photosensitizer concentration 200 mg / L); This invention group: Antibacterial agent prepared in Example 1 (red light carbon dot photosensitizer concentration 200 mg / L); Treatment procedure: Apply virus solution evenly to the underside of *N. glutinosa* leaves and allow to dry at room temperature for 10 minutes; spray with the corresponding formulation and place at 30℃ for 1 hour (to form a microgel), then immediately apply 30mW / cm² solution. 2 Irradiate with red light (660±10nm) for 15 min; after culturing at 25℃ for 5 days, count the number of dead spots; after culturing for 10 days, measure the height, fresh weight and SOD activity of the heart-leaf tobacco plants. result: Virus inactivation: The number of necrotic plaques in the present invention group was reduced by 45% compared with the control group, and the virus inactivation rate reached 99.6%, while the control group was 92.3%; Crop benefits: The height of the tobacco plants in the group of this invention was increased by 9.8% compared with the control group, the fresh weight was increased by 13.2%, and the SOD activity was increased by 28.5%, which proves that the synergistic effect of the bio-enhancing agent, carrier, and adjuvant not only strengthens the virus inactivation effect, but also significantly stimulates the crop's stress resistance, achieving the dual benefits of "disease prevention + growth promotion".

[0047] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A visible light-driven antibacterial agent, characterized by, According to the mass fraction, comprising: A composite dispersion carrier 85-99 parts by mass with temperature-sensitive and light-responsive properties; A composite surfactant 0.5-5 parts by mass; A targeted leaf surface affinity agent 0.3-2 parts by mass; A multi-level penetrant 0.5-3 parts by mass; A biological synergist 0.05-0.3 parts by mass; A pH regulator 0.05-1 parts by mass; and A red light carbon dot photosensitizer; Among them, the concentration of the red light carbon dot photosensitizer in the visible light driven antibacterial agent is 50-200 mg / L.

2. The visible light-driven antibacterial agent according to claim 1, wherein The red light carbon dot photosensitizer is prepared according to the following steps: PT2,n is an integer from 2 to 3000; Add 1M aqueous potassium hydroxide solution to the solid powder of polymer PT2, mix well; Transfer the well-mixed reaction solution into an ultrasonic reactor and react at 240-260℃ for 30-40h. After cooling, separate and purify to obtain S, N double atom-doped water-soluble carbon quantum dots.

3. The visible light-driven antibacterial agent according to claim 1, wherein The composite dispersion carrier consists of 85-95 wt% water, 1-5 wt% poly-N-isopropyl acrylamide and ethylene glycol, and the total mass percentage of water, poly-N-isopropyl acrylamide and ethylene glycol is 100 wt%; The molecular weight of the poly-N-isopropyl acrylamide is 2000-20000; The low critical solution temperature of the composite dispersion carrier is 28-32℃.

4. The visible light-driven antibacterial agent according to claim 1, wherein The composite surfactant is a compound of tea saponin and alkyl polyglycoside with a mass ratio of 2:3; The targeted leaf surface affinity agent is a compound of chitosan quaternary ammonium salt and soybean lectin with a mass ratio of 4:1; The multi-level penetrant is a compound of polyethylene glycol 200 and triglyceride with a mass ratio of 1:

2.

5. The visible light-driven antibacterial agent according to claim 1, wherein The biological synergist is a garlicin derivative; The pH regulator is a citric acid-potassium dihydrogen phosphate buffer system.

6. The visible light-driven antibacterial agent according to claim 1, wherein The pH of the visible light driven antibacterial agent is 5.5-7.5, which is in a homogeneous liquid state at an environmental temperature <28℃ and in a reversible microgel state at an environmental temperature ≥28℃.

7. The method of producing a visible light-driven antibacterial agent according to any one of claims 1 to 6, wherein The method comprises the following steps: According to the formula, add the composite surfactant, targeted leaf surface affinity agent, multi-level penetrant, biological synergist and pH regulator to the composite dispersion carrier, stir and disperse, then add the red light carbon dot photosensitizer and ultrasonic disperse to obtain the visible light driven antibacterial agent.

8. An operation method for plant disease control, characterized by, Spray the visible light driven antibacterial agent of any one of claims 1-6 evenly on the surface of the crops; wherein the spraying amount of the visible light driven antibacterial agent is 1-3 mL / plant; Raise the temperature of the crop surface to above 28℃, and under visible light irradiation conditions, achieve the killing of crop pathogens.

9. The method of claim 8, wherein, The visible light source is sunlight, xenon lamp or LED portable handheld lamp; The light intensity of the visible light is 10-100 mW / cm 2 The total irradiation time is 10-25 min, and continuous irradiation or intermittent irradiation is adopted.

10. The operating method according to claim 8, characterized in that, The crop pathogens are one or more of Botrytis cinerea, Plasmopara viticola, Clavibacter michiganensis, Xanthomonas campestris, Fusarium graminearum, Magnaporthe grisea, Xanthomonas campestris, Xanthomonas campestris, Xanthomonas campestris, Xanthomonas campestris, Xanthomonas campestris, Cassava brown streak virus, Tomato spotted wilt virus, Tobacco mosaic virus and Cucumber mosaic virus.

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