Eugenol-based irregularly detachable polymer particles and their preparation method

Abstract

This invention provides eugenol-based heteromorphic resectable polymer particles and their preparation method. The preparation method includes the following steps: synthesizing eugenol monomer from eugenol and ethyl isocyanate methacrylate; subsequently preparing seed microspheres using the eugenol monomer; modifying the eugenol to synthesize 4-(3-mercaptopropyl)-2-methoxyphenol; and grafting 4-(3-mercaptopropyl)-2-methoxyphenol onto the surface of the seed microspheres via a mercapto-olefin click chemistry reaction to obtain eugenol-based heteromorphic resectable polymer particles. The eugenol-based heteromorphic resectable polymer particles of this invention are non-toxic and harmless, possess an internally cross-linked heteromorphic structure, and can be resected to a certain extent. Furthermore, the particles also exhibit certain antibacterial activity, antioxidant activity, cell compatibility, and solvent resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer preparation, and specifically relates to an eugenol-based heteromorphic separable polymer particle and its preparation method. Background Technology

[0002] Polymer particles, with their high specific surface area and controllable diameter, hold great promise for applications in medicine, including drug release, cell culture, and tissue engineering. Naturally derived polymers possess chemical structures and compositions similar to natural extracellular matrix macromolecules, and their use as implant materials or drug delivery fields can minimize chronic inflammation, immune responses, and toxic irritation. However, many natural polymer particles themselves lack antibacterial and antioxidant properties, limiting their medical applications. Currently, the most popular approach to address this issue is loading antioxidants and antibacterial agents into the particles, but this method yields performance with poor long-term effectiveness. Furthermore, studies have explored chemical modification to achieve high and long-lasting antibacterial and antioxidant properties, but this requires separate modification of antioxidants and antibacterial agents, a cumbersome process with significant environmental pollution. Therefore, a one-step modification of natural polymer particles using green chemistry to obtain antibacterial and antioxidant properties is currently the preferred method.

[0003] Plant essential oils are among the most abundant bio-based renewable materials. Eugenol, a phenolic compound extracted from clove essential oil, possesses excellent antibacterial, antioxidant, and pharmacological activities, making it suitable for modification or direct synthesis of natural polymer particles with antibacterial and antioxidant properties. The antibacterial effect of eugenol is mainly related to the phenolic hydroxyl group, but this group is an inhibitory functional group in free radical polymerization. Therefore, most current research focuses on removing it, resulting in eugenol-based polymer particles lacking antibacterial and antioxidant properties. Therefore, synthesizing eugenol-based, heteromorphic, and separable polymer particles with potential medical applications while retaining the natural antibacterial and antioxidant properties is a key problem that needs to be solved.

[0004] Furthermore, current research has yielded polymer microparticles in a single morphology. Subsequent processing transforms these micrometer-sized particles into a few nanometer-sized particles with limited usability, or they remain shapeless altogether, thus restricting their applications. To address this issue, there is an urgent need to synthesize polymer microparticles with morphological variability, capable of transforming micrometer-sized microspheres and aggregates into individual microspheres of several hundred nanometers. Moreover, both morphologies should be applicable to various fields to some extent. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of the existing technology, the present invention provides eugenol-based shaped detachable polymer particles and its preparation method, aiming to synthesize eugenol-based shaped detachable polymer particles that can be used in biomedicine and food packaging while retaining the natural antibacterial and antioxidant properties of eugenol.

[0006] To solve the technical problem, the present invention adopts a eugenol-based heteromorphic detachable polymer particle and its preparation method, comprising the following steps:

[0007] (1) Preparation of eugenol monomer: First, 1-5g of eugenol and 1-5g of isocyanate methacrylate were added to a flask containing 10-50mL of ethyl acetate. The mixture was condensed and stirred at 15-35℃ for 18-36h. After the reaction was completed, the mixture was transferred to a separatory funnel. Unreacted eugenol was then removed by alkali washing. The oil phase was collected and rotary evaporated to obtain a white product. The white product was crushed with a mortar and pestle and placed in a cool place to air dry naturally to prepare eugenol monomer.

[0008] (2) Preparation of seed microspheres: In a three-necked flask, 0.1-0.4 g of eugenol monomer and 0.5-2 g of methacrylamide were added with 10-40 ml of acetonitrile and 5-15 ml of toluene and stirred at 180-250 rpm / min for 5-15 min. Then, 0.01-0.03 g of initiator was added, nitrogen gas was introduced and the mixture was stirred at 180-250 rpm / min for 20-40 min. The mixture was then stirred at 55-75℃ for 18-36 h. After the reaction was completed, the mixture was centrifuged at 3500-4500 rpm / min. The centrifuged product was washed three times with acetonitrile and then dried to obtain seed microspheres.

[0009] (3) Preparation of 2-methoxy-4-(propyl thioacetate)phenol: First, add 10-20g of eugenol to a three-necked flask. Under rapid stirring, add 10-20g of thioacetic acid dropwise to the flask (when adding half of the thioacetic acid, add 5-10mg of initiator under nitrogen purging). Then stir at room temperature for 18-36h, raise the temperature to 50-85℃ and stir for 60-80h. Finally, rotary evaporate to obtain 2-methoxy-4-(propyl thioacetate)phenol.

[0010] (4) Preparation of 4-(3-mercaptopropyl)-2-methoxyphenol: Dissolve 5-6g of potassium hydroxide in 40-50ml of solvent, add 5-15g of 2-methoxy-4-(propyl thioacetate)phenol under nitrogen purging, reflux and heat for 1-5h, stir at room temperature for 18-36h, after the reaction is complete, the mixture is acidified and extracted, and the organic phase is taken and rotary evaporated to obtain 4-(3-mercaptopropyl)-2-methoxyphenol;

[0011] (5) Preparation of eugenol-based morphologically detachable polymer particles: In a three-necked flask, add 3-15g of seed microspheres, 0.5-2g of 4-(3-mercaptopropyl)-2-methoxyphenol, 0.5-2g of initiator, and then add 10-30ml of acetonitrile. Stir at 60-80℃ for 60-80h. After the reaction is complete, centrifuge and wash the product three times with acetonitrile and deionized water respectively to obtain eugenol-based morphologically detachable polymer particles.

[0012] Furthermore, the initiator mentioned in step (2) is one of azobisisobutyronitrile or benzoyl peroxide.

[0013] Furthermore, the rotary evaporation temperature mentioned in steps (1), (3), and (4) is 60-90°C.

[0014] Furthermore, the drying temperature after washing the centrifuged product in step (2) is 45-75℃.

[0015] Furthermore, the solvent mentioned in step (4) is either methanol or ethanol.

[0016] Furthermore, the acidification described in step (4) uses 97% sulfuric acid.

[0017] Furthermore, the extraction in step (4) uses dichloromethane and deionized water.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The amino groups on the surface of the polymer particles prepared in this invention possess certain antioxidant capabilities. These amino groups are hydrophilic, which improves the water solubility of the particles and enhances their interaction with cells. It also facilitates the high affinity of the particles for hydrophilic active drugs. Furthermore, the grafting of 4-(3-mercaptopropyl)-2-methoxyphenol onto the particle surface maintains the antioxidant capacity, preventing the loss of antioxidant capacity due to the volatility of eugenol. Therefore, the eugenol-based, detachable, heteromorphic polymer particles prepared in this study exhibit higher antioxidant activity than eugenol, effectively reducing intracellular reactive oxygen species (ROS) and providing long-lasting antioxidant capacity.

[0020] The antibacterial effect of eugenol is mainly related to its phenolic hydroxyl groups. The eugenol-based shaped polymer particles of this invention retain the antibacterial activity of eugenol without significantly altering its antibacterial properties. Simultaneously, converting oily eugenol into hydrophilic nanoparticles helps reduce its loss during storage and enhances its antibacterial application in aquatic environments. Furthermore, the eugenol-based shaped polymer particles exhibit contact-type sterilization, allowing for repeated sterilization. The added methacrylamide in the particles also has bactericidal activity, working in conjunction with eugenol to enhance the bactericidal effect of the polymer particles. In addition, the positively charged amino groups on the surface of the eugenol-based shaped polymer particles can interact with negatively charged bacteria, further enhancing the particles' antibacterial properties.

[0021] The presence of carbon-carbon double bonds on the surface of the seed microspheres causes some microspheres to adhere together. Then, 4-(3-mercaptopropyl)-2-methoxyphenol is grafted onto these adhered "large" microspheres, forming a heteromorphic structure of eugenol-based heteromorphic detachable polymer particles. Compared to the seed microspheres, the eugenol-based heteromorphic detachable polymer particles exhibit reduced adhesion, resulting in good dispersion, a certain adsorption capacity, and a higher specific surface area. Furthermore, due to their internal cross-linked structure and heteromorphic microsphere structure, the eugenol-based heteromorphic polymer particles possess good solvent resistance.

[0022] The eugenol-based irregularly shaped and separable polymer particles prepared by this invention initially form micron-sized microsphere aggregates, which can be used as embolic materials. The microspheres within these aggregates are internally cross-linked, and there are connecting parts between the microspheres due to the capillary force of polymethacrylamide. The presence of polymethacrylamide not only maintains the shape of the eugenol-based irregularly shaped and separable polymer particles but also provides the possibility of altering the particle morphology. The capillary force between the eugenol-based irregularly shaped and separable polymer particles can be disrupted using solvents such as tetrahydrofuran, breaking the polymethacrylamide connections between the microspheres in the aggregates, resulting in 60-70% individual microspheres of several hundred nanometers in size. The cross-linking of the eugenol-based irregularly shaped and separable polymer particles prepared by this invention is just right. If the cross-linking is too high, connecting parts cannot be formed, i.e., small aggregates cannot be obtained; conversely, if the cross-linking is too low, the resulting particles are only a few nanometers in size, with low utilization value.

[0023] Ungrafted eugenol derivative particles can lead to two unfavorable situations: one is polymerization between carbon-carbon double bonds on the polymer particle surface, and the other is that uncrosslinked polymethacrylamide particles will gradually intertwine due to capillary forces, eventually causing the carbon-carbon double bonds on the eugenol to polymerize. Both situations prevent the polymer particles from being separated. The polymer particles obtained in this invention have their surface partially covered with eugenol derivatives, which are grafted onto some carbon-carbon double bonds, forming a "soothing layer" on the particle surface. This reduces the adhesion between microspheres, allowing the particles to be separated after treatment. Furthermore, due to the presence of phenolic hydroxyl groups, the particles have a certain degree of hydrophilicity, and the hydroxyl groups react with water to ionize hydrogen ions, enhancing the antioxidant properties of the eugenol-based, irregularly shaped, separable polymer particles. Attached Figure Description

[0024] Figure 1 shows the infrared spectrum of Example 1, (a) is eugenol, (b) eugenol monomer, (c) 4-(3-mercaptopropyl)-2-methoxyphenol, (d) seed microspheres, and (e) eugenol-based shaped and separable polymer particles.

[0025] Figure 2 shows the XPS wide scan spectra of seed microspheres (a) and eugenol-based sectional detachable polymer particles (b) in Example 1;

[0026] Figure 3 shows the solubility of polystyrene microsphere powder and eugenol-based sectional detachable polymer particle powder from Example 1 in three solvents: (a) N,N-dimethylformamide, (b) ethyl acetate, and (c) N,N-dimethylacetamide.

[0027] Figure 4 shows the thermal degradation curves of the seed microspheres and eugenol-based detachable polymer particles from Example 1 under a nitrogen atmosphere at 30-600℃. picture;

[0028] Figure 5 The following are SEM and TEM images from Example 1: (a) SEM image of seed microspheres; (b) SEM image of eugenol-based morphologically detachable polymer particles; (c) TEM image of seed microspheres; (d) TEM image of eugenol-based morphologically detachable polymer particles; (f) TEM image of individual nanoparticles after solvent treatment.

[0029] Figure 6 N2 adsorption-desorption isotherms for seed microspheres (a) and eugenol-based sectional detachable polymer particles (b);

[0030] Figure 7 The results of in vitro ROS reduction activity determination by DCFH-DA fluorescence method are shown in the figure. (a) Cellular fluorescence image of ROS after DCFH-DA treatment, (b) Relative fluorescence intensity of intracellular ROS after hydrogen peroxide treatment.

[0031] Figure 8The results of cytotoxicity detection of eugenol-based heteromorphic detachable polymer particles, PE and eugenol using the MTT assay are shown in the figure.

[0032] Figure 9 Water absorption rates of eugenol-based shaped detachable polymer particles and polystyrene spheres at different times at room temperature;

[0033] Figure 10 Minimum inhibitory concentrations (MICs) of commercially available eugenol and synthetic eugenol-based sectional detachable polymer particles;

[0034] Figure 11 Results of repeated antibacterial experiments on eugenol-based sectional, separable polymer particles;

[0035] Figure 12 Schematic diagram showing the changes of pure eugenol and eugenol-based heteromorphic separable polymer particles in water over time. Detailed Implementation

[0036] The present invention will be specifically described below through embodiments, which are only used to further illustrate the invention and should not be construed as limiting the scope of protection of the invention. It should be understood that after reading the contents of this invention, those skilled in the art will be able to make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0037] Example 1

[0038] The preparation method of the eugenol-based heteromorphic polymer particles with antibacterial and antioxidant functions includes the following steps:

[0039] Preparation of eugenol monomer: First, 2g of eugenol and 2.4g of isocyanate methacrylate were added to a single-necked round-bottom flask containing 22mL of ethyl acetate. The mixture was condensed at 25℃ and stirred at a constant speed for 24h. After the reaction was completed, the mixture was transferred to a separating funnel. Then, unreacted eugenol was removed by washing with alkali, and the oil phase was collected. The mixture was rotary evaporated to obtain a white product, which was then ground with a mortar and air-dried in a cool place to prepare the eugenol monomer.

[0040] Preparation of seed microspheres: In a three-necked flask, 0.22 g of eugenol monomer and 1.04 g of methacrylamide were mixed with 18.75 ml of acetonitrile and 6.25 ml of toluene and stirred at 200 rpm / min for 10 min. Then, 0.024 g of azobisisobutyronitrile was added, nitrogen gas was introduced, and the mixture was stirred at 200 rpm / min for 30 min. The mixture was stirred at 70 °C for 24 h. After the reaction was completed, the mixture was centrifuged at 4000 rpm / min. The centrifuged product was washed three times with acetonitrile and dried at 60 °C to obtain seed microspheres.

[0041] Preparation of 2-methoxy-4-(propyl thioacetate)phenol: First, 13.35 g of eugenol was added to a three-necked flask. Then, under rapid stirring, 12.15 g of thioacetic acid was added dropwise to the flask (when half of the thioacetic acid was added, 6 mg of azobisisobutyronitrile was added under nitrogen purging). The mixture was stirred at room temperature for 24 h, then stirred at 75 °C for 72 h, and rotary evaporated to obtain 2-methoxy-4-(propyl thioacetate)phenol.

[0042] Preparation of 4-(3-mercaptopropyl)-2-methoxyphenol: 5.2 g of potassium hydroxide was dissolved in 45 ml of methanol, and 10 g of 2-methoxy-4-(propyl thioacetate)phenol was added under nitrogen purging. The reaction mixture was refluxed and heated for 2 h, then stirred at room temperature for 24 h. The mixture was then acidified with 97% H₂SO₄ and extracted with CH₂Cl₂ and deionized water. The organic phase was rotary evaporated at 75 °C to obtain 4-(3-mercaptopropyl)-2-methoxyphenol.

[0043] Preparation of eugenol-based sectionally separable polymer particles: In a three-necked flask, add 6g of seed microspheres, 1g of 4-(3-mercaptopropyl)-2-methoxyphenol, 0.8g of azobisisobutyronitrile, and then add 15ml of acetonitrile. Stir at 75℃ for 72h. Centrifuge and wash three times with acetonitrile and deionized water respectively to obtain eugenol-based sectionally separable polymer particles.

[0044] Example 2

[0045] The preparation method of the eugenol-based heteromorphic polymer particles with antibacterial and antioxidant functions includes the following steps:

[0046] (1) Preparation of eugenol monomer: First, 1.0 g of eugenol and 1.2 g of isocyanate methacrylate were added to a single-necked round-bottom flask containing 12 mL of ethyl acetate. The mixture was condensed at 22 °C and stirred at a constant speed for 20 h. After the reaction was completed, the mixture was transferred to a separating funnel. Then, unreacted eugenol was washed with alkali to remove it, and the oil phase was collected. The mixture was rotary evaporated to obtain a white product, which was then ground with a mortar and air-dried in a cool place to prepare the eugenol monomer.

[0047] Preparation of seed microspheres: In a three-necked flask, 0.11 g of eugenol monomer and 0.55 g of methacrylamide were mixed with 10 ml of acetonitrile and 5 ml of toluene and stirred at 180 rpm / min for 12 min. Then, 0.01 g of azobisisobutyronitrile was added, nitrogen gas was introduced, and the mixture was stirred at 180 rpm / min for 25 min. The mixture was stirred at 65 °C for 20 h. After the reaction was completed, the mixture was centrifuged at 3800 rpm / min. The centrifuged product was washed three times with acetonitrile and dried at 55 °C to obtain seed microspheres.

[0048] Preparation of 2-methoxy-4-(propyl thioacetate)phenol: First, 12.25 g of eugenol was added to a three-necked flask. Then, under rapid stirring, 11.15 g of thioacetic acid was added dropwise to the flask (when half of the thioacetic acid was added, 5.6 mg of azobisisobutyronitrile was added under nitrogen purging). The mixture was stirred at room temperature for 20 h, then stirred at 70 °C for 65 h, and rotary evaporated to obtain 2-methoxy-4-(propyl thioacetate)phenol.

[0049] Preparation of 4-(3-mercaptopropyl)-2-methoxyphenol: 5.2 g of sodium hydroxide was dissolved in 45 ml of methanol, and 8 g of 2-methoxy-4-(propyl thioacetate)phenol was added under nitrogen purging. The reaction mixture was refluxed and heated for 2 h, then stirred at room temperature for 20 h. The mixture was then acidified with 97% H₂SO₄ and extracted with CH₂Cl₂ and deionized water. The organic phase was rotary evaporated at 70 °C to obtain 4-(3-mercaptopropyl)-2-methoxyphenol.

[0050] Preparation of eugenol-based sectionally separable polymer particles: In a three-necked flask, add 5g of seed microspheres, 0.83g of 4-(3-mercaptopropyl)-2-methoxyphenol, 0.68g of azobisisobutyronitrile, and 12ml of acetonitrile. Stir at 70℃ for 70h. Centrifuge and wash three times with acetonitrile and deionized water respectively to obtain eugenol-based sectionally separable polymer particles.

[0051] Example 3

[0052] The preparation method of the eugenol-based heteromorphic polymer particles with antibacterial and antioxidant functions includes the following steps:

[0053] Preparation of eugenol monomer: First, 4 g of eugenol and 4.8 g of isocyanate methacrylate were added to a single-necked round-bottom flask containing 40 mL of ethyl acetate. The mixture was condensed at 28 °C and stirred at a constant speed for 30 h. After the reaction was completed, the mixture was transferred to a separating funnel. Then, unreacted eugenol was removed by washing with alkali, and the oil phase was collected. The mixture was rotary evaporated to obtain a white product, which was then ground with a mortar and air-dried in a cool place to prepare the eugenol monomer.

[0054] Preparation of seed microspheres: In a three-necked flask, 0.3 g of eugenol monomer and 1.5 g of methacrylamide were mixed with 28.13 ml of acetonitrile and 9.37 ml of toluene and stirred at 250 rpm / min for 15 min. Then, 0.03 g of azobisisobutyronitrile was added, nitrogen gas was introduced, and the mixture was stirred at 220 rpm / min for 35 min. The mixture was stirred at 70 °C for 30 h. After the reaction was completed, the mixture was centrifuged at 4500 rpm / min. The centrifuged product was washed three times with acetonitrile and dried at 65 °C to obtain seed microspheres.

[0055] Preparation of 2-methoxy-4-(propyl thioacetate)phenol: First, 16.65 g of eugenol was added to a three-necked flask. Then, under rapid stirring, 15.15 g of thioacetic acid was added dropwise to the flask (when half of the thioacetic acid was added, 8 mg of azobisisobutyronitrile was added under nitrogen purging). The mixture was stirred at room temperature for 30 h, then stirred at 75 °C for 80 h, and rotary evaporated to obtain 2-methoxy-4-(propyl thioacetate)phenol.

[0056] Preparation of 4-(3-mercaptopropyl)-2-methoxyphenol: 6 g of potassium hydroxide was dissolved in 50 ml of ethanol, and 12 g of 2-methoxy-4-(propyl thioacetate) was added under nitrogen purging. The reaction mixture was refluxed and heated for 3 h, then stirred at room temperature for 30 h. The mixture was then acidified with 97% H₂SO₄ and extracted with CH₂Cl₂ and deionized water. The organic phase was rotary evaporated at 78 °C to obtain 4-(3-mercaptopropyl)-2-methoxyphenol.

[0057] Preparation of eugenol-based sectionally separable polymer particles: In a three-necked flask, add 12g of seed microspheres, 2g of 4-(3-mercaptopropyl)-2-methoxyphenol, 1.6g of azobisisobutyronitrile, and 30ml of acetonitrile. Stir at 80℃ for 80h. Centrifuge and wash three times with acetonitrile and deionized water respectively to obtain eugenol-based sectionally separable polymer particles.

[0058] Test methods

[0059] The following tests were conducted on Examples 1-3 and the comparative examples, including the following methods for testing the polymer particle chemical composition, surface morphology and internal structure, thermal stability, adsorption performance, hydrophilicity and hydrophobicity, solvent resistance, antioxidant properties, cytotoxicity, and antibacterial activity:

[0060] Chemical composition analysis: Fourier transform infrared spectra of the samples were determined using an EQUINOX 55 FTIR spectrometer (Bruker, Rheinstein, Germany). The spectra were scanned in the wavenumber range of 500–4000 cm⁻¹. Photoelectron spectra were determined using an ESCA 5600 spectrometer equipped with a MgKax X-ray source (1253.6 eV).

[0061] Surface morphology and internal structure testing: The surface morphology of the samples was observed using a scanning electron microscope (JEOL JSM-7800F) at an accelerating voltage of 10.0 kV. Transmission electron microscope images of the samples were obtained using a TEM-2000EX instrument.

[0062] Thermal stability performance test: The test was conducted using a NETZSCH TG 209 thermal analyzer in an inert nitrogen atmosphere at a temperature range of 25℃-600℃ and a heating rate of 10℃ / min.

[0063] Adsorption performance test: The adsorption / desorption isotherms of N2 were determined, and the specific surface area of ​​the sample was calculated using the BET method.

[0064] Hydrophilicity and hydrophobicity test: The sample is placed in the air at room temperature, its weight is measured at intervals, and then the water absorption rate of the sample is calculated.

[0065] Solvent resistance test: The sample is placed in a certain solvent and stirred thoroughly, and then its dissolution is observed.

[0066] Antioxidant performance testing: In vitro ROS scavenging experiments were conducted, and the oxidative stress of L-929 cells was measured using the 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence method. Cellular esterases utilize ROS to convert DCFH-DA to dichlorofluorescein.

[0067] Cytotoxicity assays: The cytotoxicity of the samples was determined using in vitro and indirect cytotoxicity assays.

[0068] Antimicrobial activity test: The antimicrobial activity of a sample is evaluated by determining its minimum inhibitory concentration (MIC).

[0069] The repeated antibacterial properties of different samples were studied using the standard colony counting method.

[0070] The test results are shown in Appendix 1-12 of the instruction manual.

[0071] As shown in Figure 1, spectrum a exhibits a typical broad band in the OH stretching region (3700-3100 cm⁻¹). Furthermore, the peak at 1637 cm⁻¹ indicates the presence of a C=C bond, and the strong vibrational peaks of the benzene ring at 1602 cm⁻¹ and 1120 cm⁻¹ are related to CO stretching. Compared to spectrum a, new vibrational peaks are clearly observed in spectrum b: the peaks of the ester group C=O (1750 cm⁻¹) and CO (1120 cm⁻¹), and the peaks of the urea group CN (1535 cm⁻¹) and NH (3345 cm⁻¹), confirming that ethyl isocyanate methacrylate has been successfully synthesized from eugenol molecules to form the eugenol monomer. Compared to spectrum a, the disappearance of the C=C vibration peak at 1637 cm⁻¹ and the appearance of the CS vibration peak at 705 cm⁻¹ are clearly observed in spectrum c, indicating that thioacetic acid has successfully synthesized 4-(3-mercaptopropyl)-2-methoxyphenol from eugenol molecules via click chemistry. In spectrum d, the C=C vibration peak at 1637 cm⁻¹ and the NH vibration peak at 3345 cm⁻¹ are observed, indicating the presence of amino and carbon-carbon double bonds on the surface of the seed microspheres synthesized from eugenol monomer and methacrylamide. Similarly, the CS vibration peak at 705 cm⁻¹ is observed in spectrum e, indicating that 4-(3-mercaptopropyl)-2-methoxyphenol has been successfully polymerized onto the surface of the seed microspheres. Furthermore, compared to spectrum d, the intensity of the C=C vibration peak in spectrum e is reduced, indicating a decrease in the number of residual C=C double bonds on the surface of the eugenol-based microspheres. This invention successfully synthesized the aforementioned eugenol-based heteromorphic polymer particles.

[0072] Figure 2 shows the XPS broad-scan spectra of the seed microspheres and the eugenol-based microspheres. A significant feature of both spectra is the presence of C, N, and O elements, with peaks at 285 eV, 400 eV, and 535 eV, respectively. The only obvious difference between the two spectra is the S2p peak of S element present in the eugenol-based microspheres, located at 164 eV, reflecting the successful grafting of 4-(3-mercaptopropyl)-2-methoxyphenol onto the microsphere surface, consistent with the Fourier transform infrared spectroscopy results.

[0073] Figure 3 shows the solubility of polystyrene microsphere powder and eugenol-based shaped, separable polymer particle powder in three solvents: N,N-dimethylformamide, ethyl acetate, and N,N-dimethylacetamide. The polystyrene microspheres are on the left, and the eugenol-based microspheres are on the right. As can be seen from the figure, the cross-linked eugenol-based microspheres remain undissolved in all three solvents. Therefore, the eugenol-based microspheres exhibit certain solvent resistance.

[0074] Figure 4 shows the thermal degradation curves of seed microspheres and eugenol-based sectional detachable polymer particles under a nitrogen atmosphere at temperatures ranging from 30 to 600°C. The temperature range for the first step of thermal degradation of the seed microspheres is 150-290°C, while that of the eugenol-based microspheres is 200-242°C. The thermal degradation curves show that the synthesized eugenol-based sectional detachable polymer particles can withstand temperatures up to 200°C, thus making them suitable for applications in high-temperature environments and exhibiting a certain degree of thermal stability.

[0075] The surface morphology of the microspheres was observed using SEM. Figure 5 As can be seen in (a), the seed microspheres have a certain spherical shape, but they are stuck together; Figure 6 In (b), the surface morphology of the eugenol-based heteromorphic separable polymer particles changed significantly compared to the seed microspheres, forming a heteromorphic structure. Furthermore, the adhesion between the microspheres was significantly reduced, and the particle size also changed, increasing from approximately 250 nm to about 1 μm. The internal structure of the polymer particles was observed using TEM. Figure 5 As seen in (c), the seed microspheres possess a shell structure, with the interior exhibiting a solid state due to cross-linking. When synthesizing eugenol-based heteromorphic detachable polymer particles, the shell structure remains, but the proportion of the internal solid structure increases, such as... Figure 5 As shown in (d), the eugenol-based heteromorphic separable polymer particles of the present invention form a heteromorphic structure, as can be seen from the combined SEM and TEM images.

[0076] Figure 6 The N2 adsorption-desorption isotherms of seed microspheres and eugenol-based irregularly shaped separable polymer particles are shown. The isotherms of both types of particles exhibit typical type II aporous adsorption behavior. The specific surface area of ​​the seed microspheres and eugenol-based irregularly shaped separable polymer particles is approximately 5.5269 m². 2 / g and 18.5742m 2 / g. Although the particle size of the eugenol-based irregularly shaped and separable polymer particles is larger than that of seed microspheres, the BET (Body Adsorption Efficiency) is increased by an order of magnitude due to the irregular surface structure and better dispersion effect (resulting in reduced adhesion). Therefore, the eugenol-based irregularly shaped and separable polymer particles of the present invention have certain adsorption properties.

[0077] Figure 7Experimental results showed that the blank control group exhibited the highest DCFH fluorescence signal among all cell types. H2O2 is a strong ROS-inducing chemical that can induce intracellular DCFH fluorescence. Treatment with eugenol-based removable polymer particles and the positive control group (eugenol + DMSO) reduced H2O2-induced ROS. DCFH fluorescence imaging confirmed the ROS reduction induced by eugenol-based removable polymer particles; compared to eugenol, the antioxidant capacity of eugenol-based removable polymer particles was significantly increased.

[0078] Figure 8 Experimental results showed that the cell viability of PE plastic and eugenol-based shaped detachable polymer particles at 24h, 48h, and 72h were 76%, 67%, 62% and 90%, 82%, 79%, respectively. Pure eugenol exhibited some toxicity to cells after 48h and 72h, while the MTT assay showed no adverse effects on L929 cell viability within 3 days, with all cell viability values ​​exceeding 75% and cytotoxicity level 1. According to standard toxicity ratings, level 1 indicates no toxicity during use. Therefore, eugenol-based shaped detachable polymer particles possess good cell compatibility.

[0079] Figure 9 The eugenol-based shaped detachable polymer particles showed a water absorption rate of 29.75% after 24 hours, while the polystyrene microspheres had a moisture absorption rate of 3.58%. Therefore, the eugenol-based shaped detachable polymer particles of the present invention have stronger hydrophilicity.

[0080] Figure 10 Eugenol-based sectionally detachable polymer particles and commercially available eugenol exhibited similar MIC values ​​against Escherichia coli, Staphylococcus aureus, and Fusobacterium nucleatum. Therefore, the eugenol-based sectionally detachable polymer particles retained the antibacterial properties of eugenol without any significant alteration.

[0081] Figure 11 Repeated antibacterial experiments on eugenol-based sectional detachable polymer particles showed that the samples had durable antibacterial properties and maintained stability even after multiple sterilization cycles.

[0082] Figure 12 When small-molecule eugenol is exposed to environmental influences in aquatic environments, it evaporates and diminishes over time. In this paper, eugenol is directly immobilized on the surface of nanospheres, preventing evaporation and diminishing, thus obtaining nanospheres with good storage stability.

[0083] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing eugenol-based, detachable, heteromorphic polymer particles, characterized in that: Eugenol monomer was synthesized from eugenol and ethyl isocyanate methacrylate; seed microspheres were then prepared using the eugenol monomer; eugenol was modified to synthesize 4-(3-mercaptopropyl)-2-methoxyphenol; 4-(3-mercaptopropyl)-2-methoxyphenol was grafted onto the surface of the seed microspheres via a mercapto-olefin click chemistry reaction to obtain eugenol-based heteromorphic detachable polymer particles, including the following specific steps: (1) Preparation of eugenol monomer: First, 1-5g of eugenol and 1-5g of isocyanate methacrylate were added to a flask containing 10-50mL of ethyl acetate. The mixture was condensed and stirred at 15-35℃ for 18-36h. After the reaction was completed, the mixture was transferred to a separatory funnel. Unreacted eugenol was then removed by alkali washing. The oil phase was collected and rotary evaporated to obtain a white product. The white product was crushed in a mortar and placed in a cool place to air dry naturally to prepare eugenol monomer. (2) Preparation of seed microspheres: In a three-necked flask, 0.1-0.4 g of eugenol monomer and 0.5-2 g of methacrylamide were added with 10-40 ml of acetonitrile and 5-15 ml of toluene and stirred at 180-250 rpm / min for 5-15 min. Then, 0.01-0.03 g of initiator was added, nitrogen gas was introduced and stirred at 180-250 rpm / min for 20-40 min. Then, the mixture was stirred at 55-75℃ for 18-36 h. After the reaction was completed, the mixture was centrifuged at 3500-4500 rpm / min. The centrifuged product was washed three times with acetonitrile and then dried to obtain seed microspheres. (3) Preparation of 2-methoxy-4-(propyl thioacetate)phenol: First, add 10-20g of eugenol to a three-necked flask. Under rapid stirring, add 10-20g of thioacetic acid dropwise to the flask. When half of the thioacetic acid has been added, add 5-10mg of initiator under nitrogen purging. Then stir at room temperature for 18-36h, raise the temperature to 50-85℃ and stir for 60-80h. Finally, rotary evaporate to obtain 2-methoxy-4-(propyl thioacetate)phenol. (4) Preparation of 4-(3-mercaptopropyl)-2-methoxyphenol: Dissolve 5-6g of potassium hydroxide in 40-50ml of solvent, add 5-15g of 2-methoxy-4-(propyl thioacetate)phenol under nitrogen purging, reflux and heat for 1-5h, stir at room temperature for 18-36h, after the reaction is completed, the mixture is acidified and extracted, and the organic phase is taken and rotary evaporated to obtain 4-(3-mercaptopropyl)-2-methoxyphenol; (5) Preparation of eugenol-based morphologically detachable polymer particles: In a three-necked flask, add 3-15g of seed microspheres, 0.5-2g of 4-(3-mercaptopropyl)-2-methoxyphenol, 0.5-2g of initiator, and then add 10-30ml of acetonitrile. Stir at 60-80℃ for 60-80h. After the reaction is complete, centrifuge and wash the product three times with acetonitrile and deionized water respectively to obtain eugenol-based morphologically detachable polymer particles.

2. The preparation method according to claim 1, characterized in that: The initiator mentioned in step (2) is either azobisisobutyronitrile or benzoyl peroxide.

3. The preparation method according to claim 1, characterized in that: The rotary evaporation temperature mentioned in steps (1), (3), and (4) is 60-90℃.

4. The preparation method according to claim 1, characterized in that: The drying temperature after washing the centrifuged product in step (2) is 45-75℃.

5. The preparation method according to claim 1, characterized in that: The solvent mentioned in step (4) is either methanol or ethanol.

6. The preparation method according to claim 1, characterized in that: The acidification described in step (4) uses 97% sulfuric acid.

7. The preparation method according to claim 1, characterized in that: The extraction described in step (4) uses dichloromethane and deionized water.

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