Method for preparing modified polylactic acid, antibacterial coating and application thereof

Abstract

The application provides an antibacterial coating, comprising a modified polylactic acid antibacterial coating; the modified polylactic acid antibacterial coating comprises modified polylactic acid and a phenolic antibacterial agent; the modified polylactic acid is prepared by the following method: S1) hydrophobic modification of lignin to obtain a macromolecular initiator; and S2) ring-opening reaction of lactide and the macromolecular initiator to obtain modified polylactic acid. Compared with the prior art, the modified polylactic acid in the antibacterial coating provided by the application not only can increase the loading amount of the phenolic antibacterial agent triclosan, slow down the release rate of the antibacterial agent, thereby providing reliable antibacterial performance, but also can improve the mechanical properties of polylactic acid, so as to ensure stable coating performance, and is particularly suitable for surface antibacterial modification of long-term implantable medical devices, complex structure implantable devices and the like.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, and particularly relates to a method for preparing modified polylactic acid, an antibacterial coating and its application. Background Technology

[0002] Medical devices, especially implantable medical devices, are widely used in modern medical technology. Microbial infection is a situation that implantable medical devices strive to avoid. Antimicrobial coatings are favored by researchers due to their low cost, stable performance, and wide applicability. By uniformly dispersing antimicrobial agents in biocompatible materials to create antimicrobial coatings, various coating methods can be used to form antimicrobial coatings on surfaces of different shapes and materials. Due to its flexible and wide-ranging applications and ease of preparation and storage, it is one of the preferred methods for preparing antimicrobial coatings.

[0003] Triclosan is a highly effective broad-spectrum antibacterial agent that kills and inhibits Gram-positive bacteria, Gram-negative bacteria, yeast, and viruses. Furthermore, it decomposes rapidly in nature, resulting in a low chance of developing drug resistance. Therefore, triclosan is widely used in high-efficiency medicated soaps (hygienic soaps), sanitary washes, deodorants (athlete's foot sprays), disinfectant hand sanitizers, wound disinfectant sprays, medical device disinfectants, hygienic facial cleansers (creams), air fresheners, and refrigerator deodorizers. It is also used in the finishing of sanitary textiles and the preservation of plastics. Higher purity triclosan is also widely used in effective toothpastes and mouthwashes for treating gingivitis, periodontitis, and oral ulcers.

[0004] Triclosan has high solubility in many organic solvents, and common implantable medical device materials are often polymers. Therefore, uniformly dispersing these medical polymers together with triclosan in an organic solvent can create an ideal antibacterial coating.

[0005] However, due to the unique phenolic structure of triclosan, its structure differs significantly from most medical polymers, resulting in poor compatibility. When coated on the surface of medical devices, the bactericide exhibits poor adhesion to the material, often leading to rapid release and excessively high local concentrations in the early stages of implantation, posing a risk of biotoxicity and significantly shortening the antibacterial effect of the implant. To address this, some researchers have chemically modified triclosan, grafting it onto polymer surfaces to meet the requirements for long-term antibacterial applications. However, chemical modification of small molecules is cumbersome and requires direct reaction on the implant surface, contradicting the initial intention of choosing triclosan as a bactericide to utilize its ability to be directly blended with polymers to create flexible coatings. Furthermore, the chemical alteration of triclosan's structure also affects its inherent bactericidal properties. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing modified polylactic acid, an antibacterial coating and its application, wherein the antibacterial coating has a long bactericidal performance and biocompatibility.

[0007] This invention provides an antibacterial coating, including a modified polylactic acid antibacterial coating; the modified polylactic acid antibacterial coating includes modified polylactic acid and a phenolic antibacterial agent;

[0008] The modified polylactic acid is prepared according to the following method:

[0009] S1) Hydrophobically modify lignin to obtain a macromolecular initiator;

[0010] S2) The lactide is mixed with the macromolecular initiator to carry out a ring-opening reaction to obtain modified polylactic acid.

[0011] Preferably, step S1) specifically involves: reacting lignin with haloalkanes by heating in the presence of an acid-binding agent to obtain a macromolecular initiator;

[0012] The mass ratio of lignin to haloalkanes is (100-0.01):1; the haloalkanes are selected from C8-C16 haloalkanes.

[0013] Preferably, the lignin and haloalkane are reacted by heating in a reaction solvent; the reaction solvent includes isopropanol and water; the mass ratio of water to isopropanol is (100-0.01):1; the reaction temperature is 100℃-180℃; and the reaction time is 24-72h.

[0014] Preferably, step S2) specifically involves: after the macromolecular initiator and organic solvent are azeotropically dehydrated, lactide and catalyst are added to carry out a ring-opening reaction to obtain modified polylactic acid.

[0015] Preferably, the mass ratio of lactide to macromolecular initiator is (1-1000):1; the ring-opening reaction temperature is 100℃-150℃; and the ring-opening reaction time is 24-72h.

[0016] Preferably, the mass ratio of the modified polylactic acid to the phenolic antibacterial agent is (1-10000):1; the phenolic antibacterial agent is selected from triclosan.

[0017] Preferably, the mass ratio of the modified polylactic acid to the phenolic antibacterial agent is (1-100):1.

[0018] Preferably, it further includes a modified polylactic acid layer laminated on the surface of the modified polylactic acid antibacterial coating; the modified polylactic acid layer comprises modified polylactic acid.

[0019] The present invention also provides an antibacterial medical device, comprising a medical device and the aforementioned antibacterial coating disposed on the surface of the medical device.

[0020] This invention also provides a method for preparing modified polylactic acid, comprising the following steps:

[0021] S1) Hydrophobically modify lignin to obtain a macromolecular initiator;

[0022] S2) The lactide is mixed with the macromolecular initiator to carry out a ring-opening reaction to obtain modified polylactic acid.

[0023] This invention provides an antibacterial coating, including a modified polylactic acid (PLA) antibacterial coating. The modified PLA antibacterial coating comprises modified PLA and a phenolic antibacterial agent. The modified PLA is prepared by the following method: S1) hydrophobically modifying lignin to obtain a macromolecular initiator; S2) mixing lactide with the macromolecular initiator to perform a ring-opening reaction to obtain modified PLA. Compared with the prior art, the modified PLA in the antibacterial coating provided by this invention not only increases the loading of the phenolic antibacterial agent triclosan and slows down the release rate of the antibacterial agent, thereby providing reliable antibacterial performance, but also improves the mechanical properties of PLA to ensure stable coating performance. It is particularly suitable for surface antibacterial modification of long-term implantable medical devices, complex implantable devices, etc.

[0024] Experimental results show that the antibacterial coating provided by the present invention can maintain effective antibacterial activity for up to 7 days. Attached Figure Description

[0025] Figure 1 The figures show the cytotoxicity test results of the coatings obtained in Examples 1, 2 and the comparative example of the present invention;

[0026] Figure 2 The graph shows the triclosan release rate test results of the coatings obtained in Examples 1, 2 and the comparative example of the present invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a method for preparing modified polylactic acid, comprising the following steps: S1) hydrophobically modifying lignin to obtain a macromolecular initiator; S2) mixing lactide with the macromolecular initiator to carry out a ring-opening reaction to obtain modified polylactic acid.

[0029] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available.

[0030] This invention introduces a phenolic structure into polylactic acid (PLA) using lignin. Lignin is a natural macromolecule, entirely synthesized by living organisms, primarily found in the xylem of plants. It is highly biodegradable, and its introduction does not compromise the biocompatibility of the material. Furthermore, lignin acts as a cell wall binder, providing a reinforcing effect in plants and imparting shock and compression resistance. In addition, due to its abundant phenolic structure, lignin possesses antioxidant properties and the ability to absorb ultraviolet light.

[0031] Lignin has a complex structure, and its thermal properties are similar to those of thermoplastic polymers, but are affected by separation methods and molecular weight. Common lignins, such as alkali lignin, contain a large number of hydroxyl groups, which easily form intramolecular hydrogen bonds, leading to lignin self-aggregation, or form hydrogen bonds with water, resulting in the presence of water molecules that are difficult to remove. Therefore, removing hydroxyl groups from lignin through esterification or nucleophilic substitution can help reduce its hydrophilicity and intermolecular hydrogen bonding, thereby reducing its self-aggregation in polymer materials or improving its processing properties. On the other hand, raw lignin is often incompatible with polymer matrices, thus requiring modification to improve its compatibility.

[0032] In this invention, lignin is hydrophobically modified through nucleophilic substitution to improve its dispersibility in organic solvents. Then, using the modified lignin as a macromolecular initiator and lactide as a monomer, lignin-modified polylactic acid (PLA) is obtained through ring-opening polymerization. Furthermore, by introducing hydrophobically modified lignin as a macromolecular initiator in the PLA synthesis process, this invention avoids the potential biotoxicity introduced by small-molecule initiators.

[0033] Specifically, lignin is hydrophobically modified to obtain a macromolecular initiator; the lignin can be any lignin well known to those skilled in the art, and there are no special limitations, but in this invention, alkaline lignin is preferred; the molecular weight of the lignin is preferably 100-10000, more preferably 500-8000, even more preferably 500-5000, even more preferably 500-3000, even more preferably 500-2000, and most preferably 500-1000; the method of hydrophobic modification can be any method well known to those skilled in the art, and there are no special limitations, but in this invention, nucleophilic substitution is preferred for hydrophobic modification, and more preferably, specifically: reacting lignin with a haloalkane in the presence of an acid-binding agent. The reaction is carried out under heating to obtain a macromolecular initiator; the haloalkane is preferably a C8-C16 haloalkane, more preferably a C10-C14 haloalkane, and even more preferably a C12 haloalkane; the halogen atom in the haloalkane can be a halogen atom well known to those skilled in the art, and there are no special restrictions. In this invention, a bromine atom is preferred; in this invention, the most preferred haloalkane is bromododecane; the mass ratio of lignin to haloalkane is preferably (100-0.01):1, more preferably (50-0.1):1, even more preferably (20-0.1):1, even more preferably (10-0.1):1, even more preferably (5-0.5):1, and most preferably (2-1):1; The acid-binding agent can be any acid-binding agent well known to those skilled in the art, and there are no special limitations. In this invention, a carbonate is preferred, and potassium carbonate is more preferred. The mass ratio of the haloalkane to the acid-binding agent is preferably (5-1):1, more preferably (3-2):1. The lignin and the haloalkane react in a reaction solvent by heating. The reaction solvent preferably includes isopropanol and water. The mass ratio of water to isopropanol is preferably (100-0.01):1, more preferably (50-0.1):1, even more preferably (20-0.1):1, even more preferably (10-0.1):1, and even more preferably (5-0.5):1. The ratio of lignin to the reaction solvent is preferably 1 g: (1-50) m The preferred concentrations are L: 1g:(3-20)mL, even more preferably 1g:(5-10)mL, and most preferably 1g:(6-10)mL; the preferred reaction temperature is 100℃-180℃, more preferably 120℃-160℃, even more preferably 130℃-150℃; the preferred reaction time is 24-72h, more preferably 36-72h, even more preferably 50-72h, and most preferably 60-72h; after the reaction, the supernatant is preferably removed by centrifugation, washed with water and dried, then washed with an organic solvent and dried to obtain a macromolecular initiator; the organic solvent can be any organic solvent known to those skilled in the art and is not particularly limited, but hexane is preferred in this invention.

[0034] Lactose is mixed with the macromolecular initiator to undergo a ring-opening reaction to obtain modified polylactic acid; the mass ratio of lactose to macromolecular initiator is preferably (1-1000):1, more preferably (5-500):1, even more preferably (5-100):1, and most preferably (10-100):1; the temperature of the ring-opening reaction is preferably 100℃-150℃, more preferably 110℃-140℃, and even more preferably 120℃-140℃; the time of the ring-opening reaction is preferably 24-72h, more preferably 36-72h, and even more preferably... The preferred time is 48-72 hours, more preferably 54-66 hours, and most preferably 60 hours. In this invention, this step is preferably specifically as follows: after the macromolecular initiator and organic solvent are subjected to azeotropic dehydration, lactide and catalyst are added to carry out a ring-opening reaction to obtain modified polylactic acid. The organic solvent can be any organic solvent well known to those skilled in the art and is not particularly limited. In this invention, toluene is preferred. The catalyst can be any catalyst well known to those skilled in the art and is not particularly limited. In this invention, stannous octoate, stannous dichloride, tetraphenyltin, and trichloride are preferred. One or more of boron; the mass of the catalyst is preferably 0.01% to 1% of the mass of lactide, more preferably 0.05% to 0.5%, and even more preferably 0.1% to 0.2%; the ring-opening reaction is preferably carried out in a protective atmosphere; the protective atmosphere can be any atmosphere known to those skilled in the art and is not particularly limited, but argon is preferred in this invention; after the ring-opening reaction, a good solvent is preferably added for dissolution, followed by precipitation with an alcohol solvent to obtain modified polylactic acid; the good solvent can be any solvent known to those skilled in the art and is not particularly limited, but dichloromethane is preferred in this invention; the alcohol solvent can be any alcohol solvent known to those skilled in the art and is not particularly limited, but methanol is preferred in this invention; to improve the purity of the modified polylactic acid, the steps of dissolving in the good solvent and precipitating with the alcohol solvent are preferably repeated multiple times, more preferably 2 to 4 times; the amount of the alcohol solvent is preferably 4 to 8 times the volume of the system after dissolution, more preferably 5 to 6 times; finally, after precipitation, drying is performed to obtain modified polylactic acid; the drying is preferably vacuum drying; the drying temperature is preferably 40℃ to 50℃.

[0035] According to the present invention, the molecular weight of the modified polylactic acid is preferably 100,000 to 500,000, more preferably 200,000 to 400,000, even more preferably 250,000 to 350,000, and most preferably 300,000.

[0036] The present invention also provides an antibacterial coating, including a modified polylactic acid antibacterial coating; the modified polylactic acid antibacterial coating includes modified polylactic acid and a phenolic antibacterial agent; the modified polylactic acid is prepared by the following method: S1) hydrophobically modifying lignin to obtain a macromolecular initiator; S2) mixing lactide with the macromolecular initiator to carry out a ring-opening reaction to obtain modified polylactic acid.

[0037] To address the issues of rapid release of phenolic antibacterial agents when simply blended with polylactic acid (PLA), and decreased bactericidal performance of chemically modified phenolic antibacterial agent coatings, this invention, based on the principle of "like dissolves like," creatively introduces a phenolic structure similar to that of phenolic antibacterial agents into the PLA structure. This ensures bactericidal reliability without altering the structure of the phenolic antibacterial agent. Furthermore, the structural similarity between the modified PLA and the phenolic antibacterial agent enhances the intermolecular forces between the phenolic antibacterial agent and the material surface, thereby improving the release rate of the phenolic antibacterial agent, prolonging the bactericidal performance, and improving the biocompatibility of the coating.

[0038] The modified polylactic acid in the antibacterial coating provided by this invention can not only increase the loading of the phenolic antibacterial agent triclosan and slow down the release rate of the antibacterial agent, thereby providing reliable antibacterial performance, but also improve the mechanical properties of polylactic acid to ensure the stability of the coating performance. It is particularly suitable for surface antibacterial modification of long-term implantable medical devices, complex implantable devices, etc.

[0039] The preparation method of the modified polylactic acid is the same as described above, and will not be repeated here.

[0040] The phenolic antibacterial agent can be any phenolic antibacterial agent well known to those skilled in the art, and there are no special restrictions. In this invention, triclosan is preferred.

[0041] According to the present invention, the mass ratio of the modified polylactic acid to the phenolic antibacterial agent is preferably (1-10000):1, more preferably (1-1000):1, even more preferably (1-500):1, even more preferably (1-300):1, even more preferably (1-100):1, even more preferably (1-50):1, even more preferably (1-20):1, even more preferably (1-10):1, and most preferably (4-10):1.

[0042] According to the present invention, the antibacterial coating further includes a modified polylactic acid layer laminated on the surface of the modified polylactic acid antibacterial coating; the modified polylactic acid layer comprises modified polylactic acid; the preparation method of the modified polylactic acid is the same as described above, and will not be repeated here. In the present invention, a double-layer coating is formed by coating a paint mixed with antibacterial drugs and a dispersion containing only modified polylactic acid twice, which can further slow down the release of phenolic antibacterial agents, improve the biosafety of the coating, and improve the physical strength of the coating.

[0043] The present invention also provides a method for preparing the above-mentioned antibacterial coating, comprising the following steps: dispersing modified polylactic acid and phenolic antibacterial agent in an organic solvent to obtain an antibacterial coating; coating the antibacterial coating on a substrate and drying it to obtain a modified polylactic acid antibacterial coating.

[0044] The antibacterial coating containing modified polylactic acid prepared by this invention has a safe and non-toxic initiator, and the coating formed by the coating has reliable strength and excellent long-term in vivo safety and antibacterial properties.

[0045] The modified polylactic acid and phenolic antibacterial agent are the same as described above, and will not be repeated here.

[0046] Modified polylactic acid and a phenolic antibacterial agent are dispersed in an organic solvent to obtain an antibacterial coating. The preferred mass ratio of the modified polylactic acid to the phenolic antibacterial agent is (1-10000):1, more preferably (1-1000):1, even more preferably (1-500):1, even more preferably (1-300):1, even more preferably (1-100):1, even more preferably (1-50):1, even more preferably (1-20):1, even more preferably (1-10):1, and most preferably (4-10):1. The organic solvent can be any organic solvent well known to those skilled in the art and is not particularly limited. In this invention, dichloromethane is preferred. The preferred mass concentration of the modified polylactic acid in the antibacterial coating is 0.01%-30%, more preferably 0.1%-10%, and even more preferably 0.5%-5%.

[0047] An antibacterial coating is applied to a substrate and dried to obtain a modified polylactic acid antibacterial coating. The substrate can be any substrate known to those skilled in the art and is not particularly limited; in this invention, a medical device is preferred. The medical device can be any medical device known to those skilled in the art and is not particularly limited; in this invention, various medical implants are preferred. The coating method can be any method known to those skilled in the art and is not particularly limited; in this invention, one or more of dip coating, spray coating, and spin coating are preferred. The drying is preferably carried out at room temperature and pressure.

[0048] According to the present invention, a modified polylactic acid coating is preferably applied to a modified polylactic acid antibacterial coating and dried to obtain an antibacterial coating; the modified polylactic acid coating comprises modified polylactic acid and an organic solvent; the organic solvent in the modified polylactic acid coating can be any organic solvent known to those skilled in the art that can be used as a coating solvent, and there are no special limitations, but dichloromethane is preferred in the present invention; the mass concentration of modified polylactic acid in the modified polylactic acid coating is preferably 0.01% to 30%, more preferably 0.1% to 10%, and even more preferably 0.5% to 5%; the coating method can be any method known to those skilled in the art, and there are no special limitations, but one or more of dip coating, spray coating, and spin coating are preferred in the present invention; the drying is preferably carried out at room temperature and pressure.

[0049] The present invention also provides an antibacterial medical device, comprising a medical device and an antibacterial coating disposed on the surface of the medical device; the antibacterial coating is the same as described above, and will not be repeated here.

[0050] More specifically, the antibacterial coating includes a polylactic acid antibacterial coating and a modified polylactic acid layer laminated on the surface of the modified polylactic acid antibacterial coating; the polylactic acid antibacterial coating is in contact with the surface of the medical device.

[0051] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a method for preparing modified polylactic acid, an antibacterial coating, and its applications.

[0052] All reagents used in the following examples are commercially available; unless otherwise specified, all medicines used in the examples were ordered from Aladdin.

[0053] Example 1

[0054] 1.1 Take 10g of lignin (alkaline), add 10g of n-dodecane bromo, 5g of potassium carbonate, 10mL of isopropanol and 50mL of water, stir thoroughly to dissolve and disperse evenly. Heat in an oil bath at 130℃ and stir for 72 hours. Centrifuge and discard the supernatant, wash the precipitate with deionized water, vacuum dry, and then wash the precipitate again with n-hexane and vacuum dry to obtain the macromolecular initiator.

[0055] 1.2 Before the reaction, all required reactors were dried and placed in a 120℃ oven for later use. Lactide, toluene (solvent), and stannous octoate (catalyst) were dried and dehydrated beforehand and stored in a vacuum oven. 2g of the macromolecular initiator obtained in 1.1 and 50mL of toluene were weighed and added to a flask. The mixture was azeotropically heated in an oil bath at 140℃ to remove water. After half of the solvent was distilled off, toluene was added to bring the volume to 50mL. This process was repeated three times. 20g of lactide and 0.02g of stannous octoate were added, and the mixture was protected under an argon atmosphere and reacted in an oil bath at 120℃ for 60 hours. After the reaction, 100mL of dichloromethane was added to the system. After stirring and dispersing evenly, five times the volume of methanol was added to precipitate the mixture. The supernatant was discarded. This process was repeated three times. The mixture was then dried completely in a 40℃ vacuum oven to obtain the modified polylactic acid material.

[0056] 1.3 Weigh a certain mass of the modified polylactic acid material obtained in 1.2 and completely dissolve it in dichloromethane solvent to make the mass fraction of modified polylactic acid in the system 5%. Then weigh a certain mass of triclosan reagent and dissolve it in the solution. The mass ratio of triclosan to modified polylactic acid is 2:8. Stir ultrasonically to disperse evenly to obtain antibacterial coating A.

[0057] 1.3 Soak polylactic acid (PLA) sheets in anhydrous ethanol and sonicate for 10 minutes, then rinse with deionized water. Repeat this process three times and allow the sheets to dry thoroughly. Apply antibacterial coating A evenly to the surface of the PLA sheet, with a coating thickness of approximately 100 μm. Allow the coating to dry completely at room temperature and pressure, then cut it into 1×3 cm samples to obtain coating Example 1.

[0058] Example 2

[0059] 2.1 Weigh a certain mass of the modified polylactic acid material obtained in 1.2 and completely dissolve it in dichloromethane solvent. The mass fraction of the modified polylactic acid is 5%, which is denoted as polylactic acid dispersion B.

[0060] 2.2 Take the fully dried coating example 1, and spray polylactic acid dispersion B evenly onto the surface of coating example 1. The coating thickness is about 100 μm. Dry it fully at room temperature and pressure to obtain coating example 2.

[0061] Comparative Example

[0062] 1.1 Before the reaction, all required reactors were dried and placed in a 120℃ oven for later use. Lactide, toluene (solvent), and stannous octoate (catalyst) were dried to remove water beforehand and stored in a vacuum oven. 2g of lignin (alkaline) and 50mL of toluene were weighed and added to a flask. The mixture was azeotropically heated in an oil bath at 140℃ to remove water. After half of the solvent was distilled off, toluene was added to bring the volume to 50mL. This process was repeated three times. 20g of lactide and 0.02g of stannous octoate were added. The mixture was protected under an argon atmosphere and reacted in an oil bath at 120℃ for 60 hours. After the reaction, 100mL of dichloromethane was added to the system. After stirring and dispersing evenly, 5 times the volume of methanol was added to precipitate the mixture. The supernatant was discarded. This process was repeated three times. The mixture was then dried completely in a 40℃ vacuum oven to obtain polylactic acid.

[0063] 1.2 Weigh a certain mass of polylactic acid and dissolve it in dichloromethane solvent. The mass fraction of polylactic acid is 5%. Weigh a certain mass of triclosan reagent and dissolve it in the polylactic acid solution. The mass ratio of triclosan to polylactic acid is 2:8. Stir ultrasonically to disperse evenly, and the comparative coating C is obtained.

[0064] 1.3 Soak the polylactic acid sheet in anhydrous ethanol and sonicate for 10 minutes, then rinse with deionized water. Repeat this process three times and allow it to dry thoroughly. Apply the control coating C evenly to the surface of the polylactic acid sheet, with a coating thickness of approximately 100 μm. Allow it to dry completely at room temperature and pressure, then cut it into 1×3 cm samples to obtain the coating comparison examples.

[0065] Polylactic acid molecular weight test and results

[0066] Test method: Gel permeation chromatography was used to determine the molecular weight of modified polylactic acid and polylactic acid. Tetrahydrofuran was used as the solvent, the measurement temperature was 30℃, and the chromatographic column was composed of tandem columns. Nine polystyrene narrow-distribution samples with molecular weights ranging from 980 to 710,000 were used as standards.

[0067] Test results: The molecular weight of the modified polylactic acid is approximately 3 × 10⁻⁶. 5 The molecular weight of polylactic acid is approximately 1.5 × 10⁻⁶. 4 The low molecular weight of polylactic acid (PLA) is due to the hydroxyl groups in unmodified lignin affecting the degree of polymerization. PLA synthesized using hydrophobically modified lignin as an initiator exhibits a significantly higher molecular weight.

[0068] Cytotoxicity test and results

[0069] Material preparation: Coating Example 1, Coating Example 2, and Coating Comparison were cut into 1×3cm samples, and uncoated polylactic acid sheets were cut as a negative control group. Sterilization was performed using moist heat sterilization.

[0070] Preparation of extract: Immerse the sample in 1640 complete culture medium, 0.2 g of sample per milliliter of culture medium, extract at 37 degrees Celsius for 24 hours, and then use the extract directly to culture cells.

[0071] Cell culture: L929 fibroblasts were passaged for 3 days, then digested with trypsin and seeded into well plates for one day of culture. The cell culture medium was then replaced with extraction medium, and the cells were cultured for another one and two days. Cell viability was then analyzed using the CCK-8 assay.

[0072] Test results are as follows Figure 1 As shown, the cell survival rate of the coating samples prepared with modified polylactic acid is higher than that of the comparative sample, and the cell survival rate of the double-layer coating Example 2 is better than that of the single-layer coating Example 1. This indicates that the antibacterial coating prepared by the present invention has excellent cell compatibility.

[0073] Triclosan release rate test and results

[0074] Drug loading determination: Coating Example 1, Coating Example 2 and the control sample were cut into 1×1cm pieces, immersed in 2mL of dichloromethane, and ultrasonically vibrated for 40min. The absorbance value at 282nm was measured by ultraviolet spectrophotometry. The drug loading of triclosan in each sample was determined according to the standard curve of triclosan in dichloromethane.

[0075] Long-term release rate determination: Coated sample 1, coated sample 2, and control sample were cut into 1×1cm pieces, and uncoated polylactic acid tablets were prepared as a negative control group. The samples were immersed in neutral PBS aqueous solution and placed in a 37°C oven. At 0, 1, 3, and 7 days of immersion, 2 mL of the aqueous solution was taken, and the absorbance at 282 nm was measured using a UV spectrophotometer. The concentration of triclosan was calculated based on the UV spectrophotometric standard curve of triclosan in water, and the release rate was calculated based on the drug loading of the corresponding samples.

[0076] The test results of the triclosan release rate of the sample are as follows: Figure 2 As shown, by Figure 2 It can be seen that the antibacterial coating prepared with modified polylactic acid has a more gradual release rate and a longer release period.

[0077] Long-lasting antibacterial test and results

[0078] Material preparation: Coated sample 1, coated sample 2, and control sample were cut into 1×1 cm pieces, and uncoated polylactic acid sheets were prepared as a negative control group. Samples were sterilized using moist heat sterilization. They were then immersed in sterile neutral PBS aqueous solution, and samples were taken and dried for use after 0, 1, 3, and 7 days of immersion.

[0079] Sterilization test: A concentration of 10... 6 Staphylococcus aureus and Escherichia coli at cfu / mL were evenly inoculated onto solid culture medium prepared with broth agar. Samples with different soaking days and control samples were placed on the culture medium inoculated with bacteria and incubated in an incubator for 1 day. Photos were taken and the diameter of the inhibition zone was measured.

[0080] The test results for the long-lasting antibacterial effect of the samples are shown in Table 1. As can be seen from Table 1, the modified polylactic acid antibacterial coating can maintain the application requirement of continuous antibacterial effect for 7 days, while the comparative sample no longer has an antibacterial effect after immersion for three days.

[0081] Table 1 Results of long-lasting antibacterial test on samples

[0082]

[0083] The preferred embodiments of the present invention disclosed above are merely for illustrating the present invention, but the present invention is not limited thereto. Those skilled in the art will understand that, within the scope of the present invention's concept, modifications can be made to the technical solutions of the present invention, or some technical features can be combined in any other way. Such modifications or combinations do not cause the essence of the corresponding technical solutions to depart from the spirit and scope of the various embodiments of the present invention, and should be considered as part of the content disclosed in the present invention, all of which fall within the protection scope of the present invention.

Claims

1. An antibacterial coating, characterized in that, The coating includes a modified polylactic acid antibacterial coating; the modified polylactic acid antibacterial coating comprises modified polylactic acid and a phenolic antibacterial agent; The modified polylactic acid is prepared according to the following method: S1) The lignin and haloalkanes are heated to react in the presence of an acid-binding agent to obtain a macromolecular initiator; S2) The lactide is mixed with the macromolecular initiator to carry out a ring-opening reaction to obtain modified polylactic acid; The modified polylactic acid has a molecular weight of 100,000 to 500,000. It also includes a modified polylactic acid layer laminated on the surface of the modified polylactic acid antibacterial coating; the modified polylactic acid layer comprises modified polylactic acid.

2. The antibacterial coating according to claim 1, characterized in that, The mass ratio of lignin to haloalkanes is (100~0.01):1; the haloalkanes are selected from C8~C16 haloalkanes.

3. The antibacterial coating according to claim 2, characterized in that, The lignin and haloalkane are reacted by heating in a reaction solvent, which includes isopropanol and water; the mass ratio of water to isopropanol is (100~0.01):1; the reaction temperature is 100℃~180℃; and the reaction time is 24~72 h.

4. The antibacterial coating according to claim 2, characterized in that, Step S2) specifically involves: after the macromolecular initiator and organic solvent are azeotropically dehydrated, lactide and catalyst are added to carry out a ring-opening reaction to obtain modified polylactic acid.

5. The antibacterial coating according to claim 4, characterized in that, The mass ratio of lactide to macromolecular initiator is (1~1000):1; the ring-opening reaction temperature is 100℃~150℃; and the ring-opening reaction time is 24~72 h.

6. The antibacterial coating according to claim 1, characterized in that, The mass ratio of the modified polylactic acid to the phenolic antibacterial agent is (1~10000):1; the phenolic antibacterial agent is selected from triclosan.

7. The antibacterial coating according to claim 1, characterized in that, The mass ratio of the modified polylactic acid to the phenolic antibacterial agent is (1~100):

1.

8. An antibacterial medical device, characterized in that, Includes a medical device and the antibacterial coating as described in any one of claims 1 to 7 disposed on the surface of the medical device.

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