Fullerene-zero-valent zinc composite antibacterial aqueous solution and preparation method thereof

Abstract

The application discloses a fullerene-zero-valent nanometer zinc composite antibacterial aqueous solution, which comprises water as a dispersion medium and composite particles dispersed in the water, wherein the composite particles have a core-shell-crown three-layer structure and comprise: a zero-valent nanometer zinc core; an intermediate layer coated on the surface of the zero-valent nanometer zinc core, wherein the intermediate layer is a fullerene layer modified by a silane coupling agent; and a crown layer coated on the outer surface of the intermediate layer, wherein the crown layer is a biological polysaccharide. The application realizes stable compounding of fullerene and high-concentration zero-valent nanometer zinc by taking water as the dispersion medium, has the advantages of high efficient antibacterial property and excellent antioxidant property, and the zero-valent zinc has high purity and the fullerene is uniformly dispersed.

Description

Technical Field

[0001] This invention relates to the field of nanocomposite antibacterial materials, and more particularly to a fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution and its preparation method. Background Technology

[0002] Zero-valent zinc nanoparticles have attracted much attention due to their high specific surface area and broad-spectrum antibacterial activity. Zero-valent zinc achieves its bactericidal effect through the release of zinc ions, the generation of reactive oxygen species, and physical damage to cell membranes, and exhibits lower cytotoxicity compared to silver-based antibacterial agents. However, zero-valent zinc nanoparticles are readily oxidized to zinc oxide in aqueous media, leading to a decrease in antibacterial activity. Furthermore, their colloidal stability is insufficient, and they are prone to aggregation and sedimentation at high concentrations. Existing zero-valent zinc nanoparticle aqueous dispersions typically have a solid content of no more than 5 wt% and a shelf life of less than 6 months, making it difficult to meet the practical application requirements of long-acting antibacterial products.

[0003] Fullerenes possess unique free radical scavenging capabilities and biocompatibility, and are often used as antioxidant components in antibacterial materials. However, fullerenes themselves do not possess direct antibacterial activity and exhibit extremely poor dispersibility in water, requiring surface modification for uniform dispersion. Existing technologies have reported the combination of fullerenes with metals or metal oxides, but these methods have the following drawbacks: First, the composite structures are simple, mostly core-shell two-layer structures, lacking an effective surface functionalization layer, resulting in limited water dispersibility, stability, and biocompatibility, making it difficult to prepare high-concentration stable aqueous solutions. Second, the binding force between zero-valent zinc and fullerenes is weak, mostly through physical adsorption or weak hydrogen bonding, making them prone to separation during long-term storage or in complex media environments. Third, the preparation processes often use organic solvents or strong reducing agents, resulting in poor environmental friendliness and difficulty in achieving precise and controllable reduction and in-situ recombination of zero-valent zinc. Fourth, existing products have limited antibacterial functions, failing to fully utilize the synergistic antioxidant effects of fullerenes, and exhibiting limited inhibitory effects on drug-resistant strains.

[0004] Therefore, it is of great significance to develop a novel composite antibacterial material that can achieve stable composite of fullerene and zero-valent zinc nanoparticles in an all-aqueous system, possesses high solid content, long-term stability, a triple antibacterial-antioxidant synergistic mechanism, and has a green and controllable preparation process. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution and its preparation method. Using water as the dispersion medium, a stable composite of fullerene and high-concentration zero-valent zinc nanocomposite is achieved, which has the advantages of high-efficiency antibacterial properties and excellent antioxidant properties. Furthermore, the zero-valent zinc has high purity and the fullerene is uniformly dispersed.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution includes water as a dispersion medium and composite particles dispersed in the water. The composite particles have a core-shell-crown three-layer structure, comprising:

[0008] Zero-valent nano zinc core;

[0009] An intermediate layer is coated on the surface of the zero-valent zinc nano core. The intermediate layer is a fullerene layer modified with a silane coupling agent.

[0010] And the canopy covering the outer surface of the intermediate layer, which is composed of biological polysaccharides.

[0011] Preferably, the aforementioned silane coupling agent is γ-mercaptopropyltrimethoxysilane; the biopolysaccharide is chitosan or sodium alginate.

[0012] Preferably, the aforementioned zero-valent zinc nano-core has a particle size of 20-80 nm, a thickness of 5-15 nm for the intermediate layer, and a thickness of 2-5 nm for the canopy.

[0013] Preferably, in the aforementioned composite particles, the solid content of zero-valent zinc nanoparticles is ≥10 wt%, and the content of fullerene is 0.05-0.1 wt%.

[0014] The preparation method of the composite antibacterial aqueous solution includes the following steps:

[0015] S1. Preparation of modified fullerene aqueous solution: Silane coupling agent and fullerene are added to deionized water, dispersed by ultrasonication, and then biopolysaccharide is added. The mixture is stirred and reacted to obtain modified fullerene aqueous solution.

[0016] S2. Preparation of zinc ion precursor solution: Add water-soluble zinc salt and composite complexing dispersant to deionized water and stir to obtain zinc ion precursor solution;

[0017] S3, Electrochemical-Chemical Synergistic Reduction: Under inert gas protection, the modified fullerene aqueous solution and zinc ion precursor solution are mixed and placed in an electrolytic cell. The composite initial dispersion is obtained by synergistic action of pulsed electrochemical reduction and chemical reduction of plant polyphenol reducing agent.

[0018] S4. Stabilization treatment: Add the compound stabilizer to the initial dispersion of the compound, stir and disperse, centrifuge to remove impurities, and obtain the compound antibacterial aqueous solution.

[0019] Preferably, in step S1, the mass ratio of silane coupling agent to fullerene is (4-6):1, and the mass ratio of biopolysaccharide to fullerene is (0.5-1):1.

[0020] Preferably, in step S2, the water-soluble zinc salt is one or both of zinc chloride and zinc acetate; the composite complexing dispersant is a mixture of polyvinylpyrrolidone, sodium polyaspartate and trisodium citrate in a mass ratio of (4.5-5.5):(1.8-2.2):(2.7-3.3); and the mass ratio of the water-soluble zinc salt to the composite complexing dispersant is 10:(1-3).

[0021] Preferably, in step S3 above, the parameters for pulsed electrochemical reduction are: pulse current density 10-50 mA / cm². 2 Duty cycle 1:3-1:5, frequency 100-500Hz; plant polyphenol reducing agent is one or more of tea polyphenols, grape seed extract or apple polyphenols, and its addition amount is 5%-15% of the mass of water-soluble zinc salt.

[0022] Preferably, in step S4 above, the compound stabilizer is a mixture of silane coupling agent modified polyethylene glycol and fatty alcohol polyoxyethylene ether in a mass ratio of 2:1, and its addition amount is 0.8%-1.5% of the mass of the composite initial dispersion.

[0023] Application of compound antibacterial aqueous solution in the preparation of medical antibacterial solution, food preservative, antibacterial finishing solution for textile fabric, daily chemical antibacterial product or environmental disinfectant.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) This invention utilizes silane coupling agent-biopolysaccharide synergistic modification to introduce a biopolysaccharide crown layer outside the zero-valent zinc nano-core and fullerene shell, forming a three-layer structure of zero-valent zinc nano-core-fullerene / silane intermediate layer-biopolysaccharide crown layer. Zero-valent zinc nano-core provides physical disruption, fullerene provides antioxidant and metabolic blocking, and biopolysaccharide provides biorecognition and adhesion, achieving a physical-chemical-biological triple antibacterial mechanism. The biopolysaccharide crown layer also provides additional steric hindrance and electrostatic repulsion, ensuring long-term stability of the high-concentration system. The amino / carboxyl groups of chitosan / sodium alginate interact with the bacterial cell membrane, enhancing the specific adsorption of drug-resistant strains. A strong Zn-S coordination bond binding mechanism is established, resulting in high stability, and the sp of fullerene... 2 The carbon network forms electron channels with zero-valent zinc through Zn-S coordination bonds, which can enhance antioxidant capacity;

[0026] (2) The present invention introduces a synergistic process of pulsed electrochemical reduction and chemical reduction of plant polyphenols, which can realize the controllable reduction of zinc ions and avoid particle growth caused by local over-reduction; plant polyphenols provide a continuous reduction environment during the electrochemical reduction interval and act as antioxidants to prevent the oxidation of zero-valent zinc; fullerenes migrate directionally to the zinc core surface through the electric field during the electrochemical reduction process, realizing true in-situ composite; the preparation process does not require organic solvents and strong reducing agents, is green and environmentally friendly, simple in process, and easy to scale up production. Attached Figure Description

[0027] Figure 1 This is a flow chart of the preparation process of the fullerene-zero-valent nano zinc composite antibacterial aqueous solution of the present invention;

[0028] Figure 2 This is a diagram illustrating the synergistic mechanism between the modified fullerene and zero-valent zinc nanoparticles of this invention ((a) oxidative protection mechanism; (b) antibacterial synergistic mechanism; (c) biocompatibility synergistic mechanism).

[0029] Figure 3 This is a TEM image of the composite antibacterial aqueous solution prepared in Example 1;

[0030] Figure 4 This is a comparison chart of the stability of Example 1 and Comparative Example 1 ((a) changes in appearance and particle size after 8 months of storage at 25°C; (b) comparison chart of particle size changes).

[0031] Figure 5 This is a comparison chart of the antibacterial rates of Example 1 and Comparative Examples 1 and 2. Detailed Implementation

[0032] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0033] A fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution includes water as a dispersion medium and composite particles dispersed in the water. The composite particles have a core-shell-crown three-layer structure, including: a zero-valent zinc nanocore; an intermediate layer coated on the surface of the zero-valent zinc nanocore, the intermediate layer being a fullerene layer modified by a silane coupling agent; and a crown layer coated on the outer surface of the intermediate layer, the crown layer being a biopolysaccharide.

[0034] The silane coupling agent is γ-mercaptopropyltrimethoxysilane KH-580; the biopolysaccharide is chitosan or sodium alginate. The particle size of the zero-valent zinc nanocore is 20-80 nm, the thickness of the intermediate layer is 5-15 nm, and the thickness of the canopy is 2-5 nm. In the composite particles, the solid content of zero-valent zinc nanoparticles is ≥10 wt%, and the content of fullerene is 0.05-0.1 wt%.

[0035] The preparation method of fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution includes the following steps:

[0036] S1. Preparation of modified fullerene aqueous solution:

[0037] Add silane coupling agent KH-580 and C60 fullerene to deionized water at a mass ratio of (4-6):1 and disperse by ultrasonication for 30-40 min; then add biopolysaccharide and stir the reaction at an ultrasonic power of 300-400W and a temperature of 40-50℃ for 2-3 h to obtain a synergistically modified fullerene aqueous solution with a mass concentration of 0.5-1.0wt%.

[0038] The biopolysaccharide is chitosan or sodium alginate. Chitosan has a degree of deacetylation ≥85% and a molecular weight of 100,000-500,000. Sodium alginate has a viscosity of 200-500 mPa·s and a mannuronic acid / guluronic acid ratio ≥1.5. Intermittent ultrasonic dispersion is used: 5 min of ultrasonication followed by a 2 min intermittent interval, for a total ultrasonic time of 30-40 min, to avoid damaging the fullerene structure.

[0039] S2. Preparation of zinc ion precursor solution:

[0040] Add water-soluble zinc salt and composite complexing dispersant to deionized water, stir to dissolve, adjust pH to 6.0-7.5, stir at 30-40℃ for 15-30 min to obtain a precursor solution with a zinc salt mass concentration of 15-25wt%.

[0041] The water-soluble zinc salt is one or both of zinc chloride and zinc acetate; the composite complexing dispersant is a mixture of polyvinylpyrrolidone, sodium polyaspartate and trisodium citrate in a mass ratio of (4.5-5.5):(1.8-2.2):(2.7-3.3); the mass ratio of water-soluble zinc salt to composite complexing dispersant is 10:(1-3).

[0042] S3, Electrochemical-Chemical Synergistic Reduction:

[0043] Under inert gas protection, a synergistically modified fullerene aqueous solution was added to the electrolytic cell as an electrolyte additive, and a zinc salt precursor solution was used as the cathode solution. Pulsed electrochemical reduction was employed (pulse current density 10-50 mA / cm²). 2 (Duty cycle 1:3-1:5, frequency 100-500Hz) and plant polyphenol reducing agent work synergistically to achieve in-situ reduction of zinc ions and simultaneous coating of fullerenes, resulting in a composite initial dispersion.

[0044] The plant polyphenol reducing agent is one or more of tea polyphenols, grape seed extract, or apple polyphenols, and its addition amount is 5%-15% of the mass of water-soluble zinc salt; the time ratio of electrochemical reduction to chemical reduction is 1:2-1:4. The pulsed electrochemical reduction adopts a constant potential-pulse current synergistic mode: first constant potential reduction for 10-20 min (potential -0.8~-1.2V vs SCE), then switch to pulsed current reduction for 30-60 min.

[0045] In the electrochemical-chemical synergistic reduction, the addition of the chemical reducing agent is preferably synchronized with the pulsed current reduction stage. During the constant potential reduction stage, the initial nucleation of zinc ions is achieved. In the subsequent pulsed current reduction stage, the simultaneous addition of plant polyphenol reducing agent effectively fills the gaps in zinc ion reduction during the pulse intervals, preventing excessive grain growth. Simultaneously, the plant polyphenols are adsorbed in situ on the newly formed zero-valent zinc surface, providing antioxidant protection. A three-electrode system is used, with a titanium mesh as the cathode, a platinum sheet as the anode, and a saturated calomel electrode as the reference electrode. Under a nitrogen atmosphere, the pulsed electrochemical reduction parameters are set as follows: pulsed current density 10-50 mA / cm². 2 The duty cycle is 1:3-1:5, and the frequency is 100-500Hz. During the reduction process, the pH of the reaction system is controlled between 6.5 and 7.2, and the plant polyphenol solution is added dropwise simultaneously through a metering pump at a rate of 0.5-0.8 mL / min to match the chemical reduction rate with the electrochemical nucleation rate.

[0046] S4. Stabilization treatment: Add compound stabilizer to the initial dispersion of the compound, stir and disperse for 20-40 min, and adjust the viscosity to 5-20 mPa·s;

[0047] The compound stabilizer is a mixture of silane coupling agent KH-560 modified polyethylene glycol 6000 and fatty alcohol polyoxyethylene ether AEO-9 in a mass ratio of 2:1. The amount added is 0.8-1.5% of the mass of the initial composite dispersion. The grafting rate of KH-560 modified polyethylene glycol 6000 is 15-25%.

[0048] S5. Impurity removal and oxygen removal encapsulation: Centrifuge at 3000-4000r / min for 10-15min to remove impurities, bubble with inert gas to remove oxygen for 15-25min, and seal and seal under inert gas protection to obtain a composite antibacterial aqueous solution.

[0049] The compound stabilizer is a mixture of silane coupling agent modified polyethylene glycol and fatty alcohol polyoxyethylene ether in a mass ratio of 2:1, and its addition amount is 0.8%-1.5% of the mass of the initial composite dispersion.

[0050] Example 1

[0051] The preparation method of fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution includes the following steps:

[0052] (1) Preparation of modified fullerene aqueous solution:

[0053] Weigh 4g of KH-580 and 1g of 99.6% pure C60 fullerene (particle size 20-30nm), add them to 195g of deionized water, and disperse them by intermittent ultrasonication (5min ultrasonication followed by 2min intermittent sonication, total time 35min, power 350W); then add 0.5g of chitosan (degree of deacetylation 90%, molecular weight 200,000), and react at 45℃ with stirring at 250r / min for 2.5h to obtain 0.5wt% synergistically modified fullerene aqueous solution.

[0054] (2) Preparation of high-concentration zinc ion composite precursor solution:

[0055] Weigh 25g of zinc chloride and add it to 80g of deionized water. Stir at 350r / min to dissolve. Add 5g of composite complexing dispersant (PVP K30 3g, sodium polyaspartate 1.2g, trisodium citrate 0.8g). Adjust the pH to 6.8 with 0.2mol / L dilute hydrochloric acid. Stir at 250r / min for 20min at a constant temperature of 35℃ to obtain a precursor solution with a zinc salt concentration of 24wt%.

[0056] (3) Electrochemical-chemical synergistic reduction

[0057] Under nitrogen protection, 50g of modified fullerene aqueous solution was mixed with the precursor solution and transferred to an electrolytic cell, using a titanium mesh (10cm² area) as the cathode. 2 Using a platinum wire as the anode and a saturated calomel electrode as the reference electrode, a constant potential reduction was first performed for 15 minutes (potential -1.0V vs SCE), followed by a pulsed current reduction for 45 minutes (pulse current density 30mA / cm²). 2 With a duty cycle of 1:4 and a frequency of 200 Hz, a tea polyphenol solution (1.2 g of tea polyphenol dissolved in 10 g of water) was added dropwise at a rate of 0.5 mL / min, a reaction temperature of 45 ℃, and a stirring rate of 400 r / min to obtain a composite initial dispersion.

[0058] (5) Stabilization and adjustment of composite systems:

[0059] Add 1.5g of compound stabilizer (KH-560 modified PEG 6000 1.0g and AEO-90.5g) to the composite initial dispersion, stir and disperse at 350r / min for 30min, and adjust the viscosity to 12mPa·s to obtain the composite dispersion.

[0060] (6) Impurity removal and deoxygenation packaging: Centrifuge at 3500 r / min for 12 min to remove impurities, bubble with nitrogen at 0.5 L / min for 20 min to remove oxygen, and pack into a brown glass bottle under nitrogen protection (headspace filled with nitrogen) to obtain a composite antibacterial aqueous solution.

[0061] Example 2

[0062] The preparation method of fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution includes the following steps:

[0063] (1) Preparation of modified fullerene aqueous solution:

[0064] Weigh 6g of KH-580 and 2g of C60 fullerene, add them to 192g of deionized water, and ultrasonically disperse them at 400W for 30min. Then add 1g of chitosan (90% degree of deacetylation, 200,000 molecular weight), and stir at 50℃ for 2h to obtain a 1.0wt% modified fullerene aqueous solution.

[0065] (2) Preparation of high-concentration zinc ion composite precursor solution:

[0066] Weigh 20g of zinc acetate and add it to 85g of deionized water. Stir at 350r / min to dissolve. Add 4g of composite complexing dispersant (PVP K30 2g, sodium polyaspartate 0.8g, trisodium citrate 1.2g). Adjust the pH to 7.2 with 0.2mol / L dilute hydrochloric acid. Stir at 250r / min for 15min at a constant temperature of 30℃ to obtain a precursor solution with a zinc salt concentration of 19wt%.

[0067] (3) Electrochemical-chemical synergistic reduction

[0068] Under nitrogen protection, 30g of modified fullerene aqueous solution was mixed with the precursor solution and transferred to an electrolytic cell, using a titanium mesh (10cm² area) as the cathode. 2 Using a platinum wire as the anode and a saturated calomel electrode as the reference electrode, a constant potential reduction was first performed for 10 minutes (potential -0.8V vs SCE), followed by a pulsed current reduction for 30 minutes (pulse current density 20mA / cm²). 2 At a duty cycle of 1:3 and a frequency of 300 Hz, grape seed extract solution (0.9 g grape seed extract dissolved in 8 g water) was added dropwise at a rate of 0.6 mL / min, a reaction temperature of 35 ℃, and a stirring rate of 300 r / min to obtain a composite initial dispersion.

[0069] (4) Stabilization and adjustment of composite systems:

[0070] Add 1g of compound stabilizer (0.67g of KH-560 modified PEG 6000 and 0.33g of AEO-9) to the composite initial dispersion, stir and disperse at 300r / min for 20min, and adjust the viscosity to 8mPa·s to obtain the composite dispersion.

[0071] (5) Impurity and oxygen removal encapsulation:

[0072] Centrifuge at 3000 r / min for 15 min to remove impurities, bubble with nitrogen at 0.3 L / min for 25 min to remove oxygen, and then pack into a brown glass bottle under nitrogen protection (headspace filled with nitrogen) to obtain a composite antibacterial aqueous solution.

[0073] Example 3

[0074] The preparation method of fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution includes the following steps:

[0075] (1) Preparation of modified fullerene aqueous solution:

[0076] Weigh 4.5g of KH-580 and 1.5g of C60 fullerene (particle size 25-35nm) with a purity of 99.6%, add them to 194g of deionized water, and ultrasonically disperse at 300W for 40min. Then add 0.75g of sodium alginate (viscosity 300mPa·s, M / G ratio 1.8), and stir at 200r / min for 3h at a constant temperature of 40℃ to obtain a 0.75wt% KH-580 modified fullerene aqueous solution.

[0077] (2) Preparation of high-concentration zinc ion composite precursor solution:

[0078] Weigh 15g of zinc chloride and 10g of zinc acetate, add them to 75g of deionized water, and stir at 400r / min to dissolve. Add 6g of composite complexing dispersant (PVP K30 3g, sodium polyaspartate 1.2g, trisodium citrate 1.8g), adjust the pH to 6.0 with 0.1mol / L dilute hydrochloric acid, and react at 40℃ with stirring at 300r / min for 30min to obtain a precursor solution with a zinc salt concentration of 25wt%.

[0079] (3) Electrochemical-chemical synergistic reduction

[0080] Under nitrogen protection, 60g of modified fullerene aqueous solution was mixed with the precursor solution and transferred to an electrolytic cell, using a titanium mesh (15cm²) as the cathode. 2 Using a platinum wire as the anode and a saturated calomel electrode as the reference electrode, a constant potential reduction was first performed for 20 minutes (potential -1.2V vs SCE), followed by a pulsed current reduction for 60 minutes (pulse current density 50mA / cm²). 2 At a duty cycle of 1:5 and a frequency of 100 Hz, apple polyphenol solution (1.5 g apple polyphenol dissolved in 12 g water) was added dropwise at a rate of 0.8 mL / min, a reaction temperature of 60 ℃, and a stirring rate of 500 r / min to obtain a composite initial dispersion.

[0081] (4) Stabilization and adjustment of composite systems:

[0082] Add 1.8g of compound stabilizer (1.2g of KH-560 modified PEG6000 and 0.6g of AEO-9) to the composite initial dispersion, stir and disperse at 400r / min for 40min, and adjust the viscosity to 20mPa·s to obtain the composite dispersion.

[0083] (5) Impurity and oxygen removal encapsulation:

[0084] Centrifuge at 4000 r / min for 10 min to remove impurities, bubble with nitrogen at 0.8 L / min for 15 min to remove oxygen, and then pack into a brown glass bottle under nitrogen protection (headspace filled with nitrogen) to obtain a composite antibacterial aqueous solution.

[0085] Comparative Example 1

[0086] The process steps of Comparative Example 1 are the same as those of Example 1, except that the modified fullerene aqueous solution in step (1) was not prepared, and a single zero-valent nano zinc antibacterial aqueous solution was obtained.

[0087] Comparative Example 2

[0088] Comparative Example 2 follows the same process steps as Comparative Example 1, except that 1g of unmodified C60 fullerene was added to a single zero-valent nano zinc antibacterial aqueous solution and ultrasonically dispersed at 350W for 30min.

[0089] Comparative Example 3

[0090] The process steps of Comparative Example 3 are the same as those of Example 1, except that the mass ratio of KH-580 to C60 fullerene in step (1) is changed to 1:1.

[0091] Comparative Example 4

[0092] Preparation of zinc nanoparticles supported by ethylenediamine-amylated fullerene:

[0093] (1) 0.5g of C60 fullerene was ultrasonically dispersed in 50mL of anhydrous ethanol, 5mL of ethylenediamine was added, and the mixture was reacted at 60℃ for 4h to obtain aminated fullerene.

[0094] (2) Disperse the aminated fullerene in 100 mL of water, add 2 g of Zn(NO3)2, and stir for 2 h;

[0095] (3) Add 0.5g NaBH4 (dissolved in 10mL ice water), stir and reduce at 0℃ for 30min, filter, wash 3 times with deionized water, and vacuum dry (40℃, 12h) to obtain solid powder.

[0096] Comparative Example 5

[0097] Comparative Example 5 has the same process steps as Example 1, except that in step (3), only chemical reduction is performed, without synergistic electrochemical reduction. The specific steps are as follows:

[0098] 50g of modified fullerene aqueous solution was mixed with tea polyphenol solution (1.2g of tea polyphenol dissolved in 10g of water) and then added dropwise to the precursor solution at a rate of 0.5mL / min. The reaction temperature was 45℃ and the stirring rate was 400r / min to obtain the composite initial dispersion.

[0099] Comparative Example 6

[0100] Comparative Example 6 has the same process steps as Example 1, except that in step (3), only electrochemical reduction is performed, without synergistic chemical reduction. The specific steps are as follows:

[0101] Under nitrogen protection, 50g of modified fullerene aqueous solution was mixed with the precursor solution and transferred to an electrolytic cell, using a titanium mesh (10cm² area) as the cathode. 2 Using a platinum wire as the anode and a saturated calomel electrode as the reference electrode, a constant potential reduction was first performed for 15 minutes (potential -1.0V vs SCE), followed by a pulsed current reduction for 45 minutes (pulse current density 30mA / cm²). 2 (Duty cycle 1:4, frequency 200Hz) to obtain the composite initial dispersion.

[0102] Performance testing

[0103] (1) The performance of the products in Examples 1-3 and Comparative Examples 1-6 was tested. The specific methods were as follows: the solid content of zero-valent zinc was determined by thermogravimetric analysis. The temperature was increased to 600℃ at 10℃ / min under a nitrogen atmosphere, and the solid content was calculated by residual mass. The purity of zero-valent zinc was determined by X-ray photoelectron spectroscopy analysis of the Zn 2p3 / 2 peak. The peaks were fitted according to the binding energy positions of zero-valent zinc and zinc oxide. The fullerene content was determined by ultraviolet-visible spectrophotometry and compared with the standard curve. The particle size and particle size distribution coefficient of the composite particles were determined by dynamic light scattering. The test temperature was 25℃. The sample was diluted to about 0.01wt% and equilibrated for 120 seconds. The DPPH free radical scavenging rate was determined by Brand-Williams method. The sample was reacted with 0.1mmol / L DPPH ethanol solution for 30 minutes, and the absorbance change at 517nm was measured. The antibacterial rate was determined by the shaking method according to GB / T 20944.3-2008. The test strains included Escherichia coli ATCC. 25922, Staphylococcus aureus ATCC 6538, Candida albicans ATCC 10231, and methicillin-resistant Staphylococcus aureus ATCC 43300, with a bacterial suspension concentration of approximately 1×10⁻⁶. 5 The sample was mixed with an equal volume of bacterial solution at CFU / mL and then shaken at 37°C for 24 hours. After serial dilution and plating, the samples were counted and the antibacterial rate was calculated. The results are shown in Tables 1 and 2.

[0104] Table 1 Performance of the products in Examples 1-3 and Comparative Examples 1-4

[0105]

[0106] Table 2. Antimicrobial properties of the products in Examples 1-3 and Comparative Examples 1-4

[0107]

[0108] As shown in Table 1, the zero-valent zinc solid content in Examples 1-3 was all above 10 wt%, the purity of zero-valent zinc was all above 99%, the particle size range of the composite particles was 30-100 nm, and the particle size distribution index (PDI) did not exceed 0.33. Comparative Example 5 used a single chemical reduction method, resulting in particle sizes increased to 80-150 nm, a PDI increased to 0.45, and a zero-valent zinc purity decreased to 96.5%. Comparative Example 6 used a single electrochemical reduction method, with particle sizes of 70-120 nm, a PDI of 0.38, and a purity slightly lower than the examples. This indicates that when electrochemical and chemical reduction work synergistically, the fine crystal nuclei formed during the constant potential stage are supplemented by the simultaneously added plant polyphenols during the subsequent pulse reduction process, inhibiting excessive crystal growth and oxidation side reactions, thus resulting in smaller particle size, narrower distribution, and higher purity. In Comparative Example 3, the PDI increased to 0.42 after the amount of silane coupling agent was reduced, indicating that insufficient coupling agent resulted in inadequate fullerene surface modification, making it impossible to stably anchor the fullerene to the zinc core surface via Zn-S coordination bonds, leading to easy particle adhesion. Comparative Example 2, which involved preparing zero-valent zinc first and then composited with fullerene, saw a sharp drop in the purity of zero-valent zinc to 92.1%, indicating that the subsequent composite process not only failed to form an effective coating but also exacerbated the oxidation of zero-valent zinc. Furthermore, the DPPH radical scavenging rates of Examples 1-3 were all above 91%, while Comparative Examples 5 and 6 were 88% and 85%, respectively. Uniform fullerene coating on the zinc core surface helps increase its contact area with free radicals, thus exerting a more complete antioxidant effect. As can be seen from the parameters in Table 1, the electrochemical and chemical synergistic reduction process and the KH-580-mediated Zn-S coordination bonds are key factors in achieving high concentration, high purity, small size, and good dispersibility.

[0109] Table 2 shows the antibacterial test results, indicating that Examples 1-3 achieved antibacterial rates of no less than 99.6% against *Escherichia coli*, *Staphylococcus aureus*, *Candida albicans*, and drug-resistant *Staphylococcus aureus*. Comparative Examples 5 and 6 achieved antibacterial rates of 96.8% and 97.2% against drug-resistant bacteria, respectively, lower than Examples 1-3. Comparative Example 1, without the addition of fullerene and biopolysaccharide, achieved an antibacterial rate of 98.5% against drug-resistant bacteria. The post-compounding method in Comparative Example 2 further reduced the antibacterial rate to approximately 94%. Comparative Example 4, using the existing method of loading zinc onto ethylenediamine-amino-fullerene, achieved an antibacterial rate of 97.5% against drug-resistant bacteria. This demonstrates that the antibacterial effects of Examples 1-3 are directly related to their particle structure. The zero-valent zinc core can disrupt bacterial cell membranes by releasing zinc ions and generating reactive oxygen species. The fullerene interlayer can enter the bacterial cell and interfere with DNA replication. The biopolysaccharide canopy carries a positive charge and can actively adsorb onto the negatively charged bacterial surface, simultaneously weakening the efflux mechanism of drug-resistant bacteria and enhancing cell wall permeability. When the particle size is uniform and the three-layer structure is intact, these three mechanisms of action can work synergistically. Comparative Example 5, due to its larger particle size and uneven coating, exhibited weakened targeting and synergistic effects. Comparative Example 6, lacking immediate protection from plant polyphenols, suffered from poor surface conditions of zero-valent zinc, impacting the subsequent canopy assembly quality. Therefore, the results in Table 2 indicate that only by constructing an ordered three-layer composite structure through a synergistic electrochemical and chemical reduction process can the synergistic antibacterial mechanism of zero-valent zinc, fullerene, and biopolysaccharides be effectively mobilized, resulting in strong inhibition against drug-resistant strains.

[0110] (2) Samples of the fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution prepared in Example 1 were taken, dropped onto a copper mesh, and observed using a transmission electron microscope (TEM) in a high-vacuum environment with a high-energy electron beam penetrating the sample to examine the microstructure, size, dispersion state, and internal structural contrast of the composite particles. The results are shown in […]. Figure 3 .

[0111] pass Figure 3 As shown in the figure, a large number of near-spherical or slightly irregular nanoparticles are uniformly dispersed without obvious aggregates, and the size of individual particles is approximately in the range of 40-70 nm. The core-shell-crown three-layer structure is clearly visible, with the highest electron density in the central region of the particle, exhibiting a deep black contrast, corresponding to the zero-valent zinc nanocore. Surrounding the dark core is a relatively uniform, light-contrast gray translucent layer, corresponding to the fullerene layer modified by the silane coupling agent. This layer has a clear boundary with the zinc core, proving that the fullerene has been successfully coated on the surface of the zinc core. At the outer edge of the middle layer, an extremely thin, light-contrast, slightly blurred halo layer is visible, corresponding to the biopolysaccharide crown layer. The boundaries between the particles are distinct, without sintering or adhesion, indicating that the composite particles have good monodispersity in the liquid phase. Figure 3The clearly defined three-layer structure observed confirms that during the preparation process, fullerenes were adsorbed in situ onto the surface of the newly formed zinc nuclei under electrochemical reduction. The fullerenes then formed Zn-S coordination bonds with the zinc nuclei through the thiol groups (-SH) of KH-580, achieving a strong chemical bond rather than physical mixing. Subsequently, chitosan formed on the outside of the fullerene layer through hydrogen bonding and electrostatic interactions, forming an outer protective cap.

[0112] (3) Example 1 and Comparative Example 1 were stored at a constant temperature of 25°C in a sealed, light-protected environment for 8 months. After the experiment, the appearance changes of the samples (whether sedimentation, stratification, or discoloration occurred) were observed and recorded by the naked eye, and the particle size changes were detected by dynamic light scattering (DLS). The results are shown in the figure. Figure 4 .

[0113] pass Figure 4 As shown in (a), the liquid in the sample bottle of Example 1 was clear and transparent, with no sediment at the bottom and no floating matter on the surface, exhibiting good fluidity. The liquid in the sample bottle of Comparative Example 1 was significantly turbid, with visible gray sediment at the bottom and an oxide layer on the surface. Figure 4 As shown in (b), the initial particle size of the particles in Example 1 was approximately 55 nm, and after 8 months, the particle size was approximately 62 nm, with a particle size growth rate of only 12.7%. In Comparative Example 1, the initial particle size was approximately 50 nm, and after 8 months, the particle size increased to approximately 90 nm, with a particle size growth rate of 80%, a significantly faster growth rate. This indicates that Example 1 has better stability because the thiol groups of KH-580 form strong chemical bonds with the zinc core surface, anchoring the fullerene interlayer and preventing it from detaching from the zinc core surface. Furthermore, the fullerene interlayer acts as a physical barrier, isolating oxygen and moisture from diffusing into the zinc core, significantly inhibiting the oxidation of zero-valent zinc. The outward extension of the chitosan molecular chains provides a strong steric hindrance effect and electrostatic repulsion, preventing particles from approaching each other, colliding, and agglomerating. In Comparative Example 1, the surface of the single zero-valent zinc nanoparticles only has a small amount of physical adsorption of dispersants such as PVP, lacking a strong chemical coating layer and canopy steric hindrance. At high concentrations, van der Waals forces dominate between particles, making them prone to aggregation. Meanwhile, the surface of zero-valent zinc is directly exposed to dissolved oxygen in water, slowly oxidizing to form ZnO or Zn(OH)2. The density and morphology of the oxidation products change, which intensifies sedimentation and phase separation.

[0114] (4) Using the colony counting method, the products of Example 1, Comparative Example 1, and Comparative Example 2 were exposed to four test strains (Escherichia coli, Staphylococcus aureus, Candida albicans, and drug-resistant Staphylococcus aureus) for a certain period of time. The antibacterial rate of each sample against bacteria was calculated, and the results are shown in […]. Figure 5 .

[0115] pass Figure 5It can be seen that Example 1 has the broadest antibacterial spectrum and the highest activity: the antibacterial rate against all four strains is ≥99.7%, especially maintaining an extremely high activity of 99.7% against drug-resistant Staphylococcus aureus. Comparative Example 1 has insufficient activity against drug-resistant bacteria. Although the antibacterial rate against common strains is acceptable, the antibacterial rate against drug-resistant Staphylococcus aureus is only 98.5%, significantly lower than that of Example 1. The performance of Comparative Example 2 is generally reduced. Due to the aggregation of fullerene and the oxidation of zero-valent zinc during the compounding process, its antibacterial activity is severely impaired, and the antibacterial rate against Escherichia coli drops to 97.8%.

[0116] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A fullerene-zero-valent zinc nanocomposite antibacterial aqueous solution, characterized in that, This includes water as a dispersion medium, and composite particles dispersed in the water, said composite particles having a core-shell-crown three-layer structure, including: Zero-valent nano zinc core; An intermediate layer coated on the surface of a zero-valent zinc nano core, wherein the intermediate layer is a fullerene layer modified with a silane coupling agent; And a canopy covering the outer surface of the intermediate layer, wherein the canopy is a biological polysaccharide.

2. The composite antibacterial aqueous solution according to claim 1, characterized in that, The silane coupling agent is γ-mercaptopropyltrimethoxysilane; the biopolysaccharide is chitosan or sodium alginate.

3. The composite antibacterial aqueous solution according to claim 1, characterized in that, The zero-valent zinc nanonuclei have a particle size of 20-80 nm, the intermediate layer has a thickness of 5-15 nm, and the canopy has a thickness of 2-5 nm.

4. The composite antibacterial aqueous solution according to claim 1, characterized in that, In the composite particles, the solid content of zero-valent zinc nanoparticles is ≥10 wt%, and the content of fullerene is 0.05-0.1 wt%.

5. The method for preparing the composite antibacterial aqueous solution according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Preparation of modified fullerene aqueous solution: Silane coupling agent and fullerene are added to deionized water, dispersed by ultrasonication, and then biopolysaccharide is added. The mixture is stirred and reacted to obtain modified fullerene aqueous solution. S2. Preparation of zinc ion precursor solution: Add water-soluble zinc salt and composite complexing dispersant to deionized water and stir to obtain zinc ion precursor solution; S3, Electrochemical-Chemical Synergistic Reduction: Under inert gas protection, the modified fullerene aqueous solution and zinc ion precursor solution are mixed and placed in an electrolytic cell. The composite initial dispersion is obtained by synergistic action of pulsed electrochemical reduction and chemical reduction of plant polyphenol reducing agent. S4. Stabilization treatment: Add the compound stabilizer to the initial dispersion of the compound, stir and disperse, centrifuge to remove impurities, and obtain the compound antibacterial aqueous solution.

6. The preparation method according to claim 5, characterized in that, In step S1, the mass ratio of silane coupling agent to fullerene is (4-6):1, and the mass ratio of biopolysaccharide to fullerene is (0.5-1):

1.

7. The preparation method according to claim 5, characterized in that, In step S2, the water-soluble zinc salt is one or both of zinc chloride and zinc acetate; the composite complexing dispersant is a mixture of polyvinylpyrrolidone, sodium polyaspartate and trisodium citrate in a mass ratio of (4.5-5.5):(1.8-2.2):(2.7-3.3); and the mass ratio of the water-soluble zinc salt to the composite complexing dispersant is 10:(1-3).

8. The preparation method according to claim 5, characterized in that, In step S3, the parameters for pulsed electrochemical reduction are: pulse current density 10-50 mA / cm². 2 Duty cycle 1:3-1:5, frequency 100-500Hz; plant polyphenol reducing agent is one or more of tea polyphenols, grape seed extract or apple polyphenols, and its addition amount is 5%-15% of the mass of water-soluble zinc salt.

9. The preparation method according to claim 5, characterized in that, In step S4, the compound stabilizer is a mixture of silane coupling agent modified polyethylene glycol and fatty alcohol polyoxyethylene ether in a mass ratio of 2:1, and its addition amount is 0.8%-1.5% of the mass of the composite initial dispersion.

10. The use of the composite antibacterial aqueous solution according to any one of claims 1-4 in the preparation of medical antibacterial solutions, food preservatives, antibacterial finishing solutions for textile fabrics, daily chemical antibacterial products, or environmental disinfectants.

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