A nano-antifungal preparation based on temperature and pH dual response and a preparation method thereof

Abstract

The application discloses a kind of nano mildew-proof preparation based on temperature and pH dual response and preparation method thereof, belong to material preparation technical field.The present application uses aminated mesoporous silica MSN-NH2 as inorganic core, covalent grafting temperature-sensitive polymer shell through imine bond, mesoporous interior is loaded IPBC mildew-proof agent, obtains nano mildew-proof preparation.Imine bond simultaneously undertakes carrier-connection bridge, acid-sensitive drug release switch dual function, temperature response as warehouse long-acting lock medicine barrier, avoid high temperature environment drug loss in advance, pH response realizes the accurate directional release of mould growth site, neutral mould-free environment reduces invalid drug loss, realizes the double regulation of high-temperature lock medicine and mould acidic site directional release, greatly reduces the total dosage of IPBC, solves the pain points of traditional preparation without targeted release, drug waste, and the utilization rate of drug is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, specifically relating to a nano-antifungal agent based on dual temperature and pH responses and its preparation method. Background Technology

[0002] Fabrics are highly susceptible to the growth of molds such as Aspergillus niger in storage and high-temperature, high-humidity environments. Mold can cause fiber degradation and fabric discoloration, while mold spores and metabolic toxins pose health risks. Currently, the mainstream IPBC anti-mold system in the industry has the following main shortcomings: (1) Free IPBC agent release is uncontrolled and has a very short anti-mold period: Free IPBC is not bound by a carrier and evaporates quickly in a humid and hot environment and is washed away by water. The effective anti-mold period is usually less than 7 days. Mold will reproduce in large quantities again in a long-term storage environment, requiring frequent replenishment. The cost of use is high and the operation is cumbersome.

[0003] (2) No environmental targeted recognition response mechanism, and extremely low agent utilization rate: Existing technologies are difficult to identify specific environmental conditions for mold growth (such as temperature and pH value). Free IPBC does not have the ability to identify and regulate temperature or pH. Regardless of whether the ambient temperature reaches the suitable reproduction range of mold or whether the fabric produces a mold-producing acid microenvironment, most IPBC is ineffectively lost. The anti-mold agent is ineffectively released in non-target environments and cannot respond in time when needed, resulting in low raw material utilization efficiency.

[0004] (3) Insufficient load stability: Conventional load methods (such as adsorption or coating) are prone to cause the loss of antifungal agents, which is especially obvious under high temperature and high humidity conditions, accelerating the failure of antifungal agents and affecting the long-term antifungal effect.

[0005] Therefore, it is necessary to develop an antifungal agent that can target environmental factors to improve drug utilization. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a nano-antifungal agent based on dual temperature and pH response and its preparation method, so as to solve the technical problem that free IPBC cannot achieve targeted recognition and release based on temperature and pH.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for preparing a nano-antifungal agent based on dual temperature and pH responses, comprising the following steps: S1. Preparation of MSN-NH2 support: Mesoporous silica (MSN) powder (pore size 2-5 nm, specific surface area ≥1000 m²) 2 / g) is ultrasonically dispersed in an organic solvent to ensure no agglomeration of the powder. Then, a silane coupling agent is added under nitrogen atmosphere, and the mixture is refluxed at 65-75℃ under nitrogen atmosphere for 10-14 hours. The alkoxy groups of the silane coupling agent are hydrolyzed and undergo siloxane bond condensation with the silanol groups on the surface of mesoporous silica, introducing primary amino groups onto the MSN surface to obtain an aminated MSN-NH2 support. The ratio of mesoporous silica powder to silane coupling agent is 8-12 mg: 45-55 μL. S2. Preparation of intermediate two; S21. Acrylamide monomers, initiators, and chain transfer agents are dissolved in an organic solvent at a mass ratio of 3-7:0.05-0.1:0.03-0.08. Then, oxygen in the reaction system is removed, and the reaction is carried out in a nitrogen atmosphere at 65-70℃ for 22-26 hours. The initiator decomposes upon heating to produce free radicals, which initiate free radical polymerization of acrylamide monomers. The chain transfer agent terminates chain growth and introduces hydroxyl groups at the ends of the polymer chains to obtain hydroxyl-terminated intermediate one. S22. Intermediate 1, p-formylbenzoic acid, carbodiimide condensing agent, and pyridine nucleophilic catalyst are dissolved in an organic solvent at a mass ratio of 1-3:0.4-0.8:0.5-1:0.05-0.15, and then reacted in the dark for 22-26 hours. p-Formylbenzoic acid is a bifunctional aromatic compound containing both carboxyl and aldehyde groups. The condensing agent activates the carboxyl group of p-formylbenzoic acid, which undergoes a Steglich esterification reaction with the terminal hydroxyl group of intermediate 1, introducing an aldehyde group into the end of the polymer chain. This provides an aldehyde group reaction site for subsequent Schiff base condensation with MSN-NH2. After the esterification grafting to introduce the aldehyde group active site is completed, intermediate 2 is obtained. S3. Dissolve MSN-NH2 support and intermediate II in an organic solvent at a mass ratio of 5-15:40-60, and then stir the reaction at 35-45℃ for 4-8 hours. The primary amino group on the surface of MSN-NH2 undergoes Schiff base condensation reaction with the aldehyde group of intermediate II, and dehydrates to form an imine covalent bond, thus completing the covalent grafting of the thermosensitive polymer and obtaining the core-shell structured intermediate III. S4. The intermediate trioxide and the antifungal agent are mixed in an organic solvent at a mass ratio of 3-7:1-3. The mixture is stirred for 70-74 hours under light-protected conditions. The antifungal agent diffuses fully into the mesoporous channels inside the MSN through molecular diffusion, thus completing the drug loading. The temperature is then raised to 35-40℃ and stirring is continued for 22-26 hours. Finally, the mixture is freeze-dried to obtain the nano-antifungal formulation. The antifungal agent is IPBC (3-iodo-2-propynyl-N-n-butylcarbamate).

[0008] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, the organic solvent is a polar aprotic organic solvent.

[0009] Furthermore, the organic solvent is anhydrous ethanol, 1,4-dioxane, dichloromethane, dimethyl sulfoxide, tetrahydrofuran, or N,N-dimethylformamide. The organic solvent is used to dissolve the reactants, provide a homogeneous reaction environment, and can also be used for washing and purifying the products.

[0010] Furthermore, the silane coupling agent is an alkoxysilane containing a primary amino group; the initiator is an azo compound; and the chain transfer agent is a thiol compound containing both a mercapto group and a hydroxyl group.

[0011] Furthermore, the silane coupling agent is 3-aminopropyltriethoxysilane (APTES); the initiator is azobisisobutyronitrile (AIBN); and the chain transfer agent is mercaptoethanol. The silane coupling agent is used to aminate mesoporous silica, introducing primary amino active sites on the silica surface to provide reaction sites for subsequent Schiff base condensation reactions; the initiator decomposes upon heating to generate free radicals, initiating free radical polymerization of acrylamide monomers; and the chain transfer agent is used to control the polymer molecular weight and introduce hydroxyl functional groups at the polymer chain ends.

[0012] Furthermore, the acrylamide monomers are N-isopropylacrylamide (NIPAM) or N,N-diethylacrylamide (DEAA). N-isopropylacrylamide is a thermosensitive polymerizable monomer that forms PNIPAM polymer segments after polymerization, giving the material a minimum critical dissolution temperature of 32°C and achieving temperature-responsive drug-locking function.

[0013] Furthermore, the carbodiimide condensing agent is dicyclohexylcarbodiimide (DCC); the pyridine nucleophilic catalyst is 4-dimethylaminopyridine (DMAP). The condensing agent is used to activate the carboxylic acid group and promote the esterification reaction; the catalyst is used to improve the grafting efficiency of the esterification reaction.

[0014] Furthermore, the freeze-drying temperature in S4 is -40~-50℃, and the time is 22-26h.

[0015] The present invention also discloses a nano-antifungal agent based on dual temperature and pH response prepared by the above preparation method.

[0016] This invention also discloses the application of the above-mentioned nano-antifungal agents based on dual temperature and pH responses in the field of fabric antifungal treatment.

[0017] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, the concentration of the nano-antifungal agent is 15-240 mg / L when used.

[0018] The beneficial effects of this invention are as follows: 1. By grafting thermosensitive polymers with covalent bonds, the drug loading rate of IPBC is significantly increased to 58.1%, and the loading capacity of MSN carrier is significantly improved, solving the defects of low loading capacity and easy drug desorption and loss of pure MSN carrier, and reducing IPBC raw material loss.

[0019] 2. Imine bond coupled temperature / pH dual-response structure: The imine bond simultaneously serves as a carrier-connecting bridge and an acid-sensitive drug release switch. Combined with the drug-locking properties of temperature-sensitive acrylamide monomers, the temperature response acts as a long-term drug-locking barrier in storage, preventing premature drug loss in high-temperature environments. The pH response enables precise and targeted drug release at mold growth sites, and the neutral, mold-free environment reduces the loss of ineffective drugs. The two work synergistically to improve the accuracy and durability of anti-mold treatment, achieving dual regulation of high-temperature drug lock-in and targeted drug release at acidic mold sites. This significantly reduces the total amount of IPBC feed, solving the pain points of traditional formulations such as non-targeted release and drug waste, and greatly improving drug utilization.

[0020] 3. When the ambient temperature is below the critical dissolution temperature of the thermosensitive acrylamide monomer, the polymer molecular chains expand, allowing IPBC loading. When the ambient temperature is above the critical dissolution temperature, the polymer chain segments undergo hydrophobic collapse, tightly encapsulating and blocking the MSN mesoporous channels. Utilizing the thermosensitive properties of the thermosensitive acrylamide monomer, a protective layer is formed at high temperatures, inhibiting premature IPBC release. After constant-temperature incubation to release equilibrium, the equilibrium drug release in the nano-antifungal agent prepared by this invention is 42.16% at 25°C, while the equilibrium release at 37°C is only 29.76%, a reduction of approximately 30%. This inhibits premature IPBC leakage under high-temperature and humid storage conditions at the molecular structure level.

[0021] 4. Application of low-concentration long-lasting fabric finishing: A single impregnation of cotton fabric with the nano antifungal agent prepared by the present invention at a concentration of 240 mg / L can achieve 28 days of national standard level 0 antifungal protection under continuous high temperature and humidity culture at 35℃. Free IPBC requires 450 mg / L to maintain only 7 days of short-term level 0 antifungal protection. Under the same long-lasting conditions, the IPBC raw material consumption of the preparation of the present invention is significantly reduced, improving economic efficiency and environmental friendliness. Attached Figure Description

[0022] Figure 1 The absorbance-concentration standard curve of IPBC in DMSO; Figure 2 A bar chart comparing the drug loading of MSN@IPBC and PNIPAM-MSN@IPBC; Figure 3 A bar chart comparing the drug loading rates of MSN@IPBC and PNIPAM-MSN@IPBC; Figure 4 This is a standard curve of IPBC absorbance-concentration in anhydrous ethanol. Figure 5The cumulative drug release curves of PNIPAM-MSN@IPBC at different temperatures; Figure 6 This is a comparison of the drug release kinetics fitting of PNIPAM-MSN@IPBC at 25℃; Figure 7 This is a comparison of the drug release kinetics fitting of PNIPAM-MSN@IPBC at 32℃; Figure 8 This is a comparison of the drug release kinetics fitting of PNIPAM-MSN@IPBC at 37℃; Figure 9 The IPBC absorbance-concentration standard curve for the MES-ethanol mixture system; Figure 10 Bar chart showing the cumulative release rate of IPBC over 12 hours under different pH conditions; Figure 11 Images showing the growth of Aspergillus niger on fabrics treated with different concentrations of free IPBC solution for 7 days. Figure 12 Figure 1 shows the growth sequence of Aspergillus niger on fabrics treated with different concentrations of PNIPAM-MSN@IPBC solution from 0 to 28 days. Detailed Implementation

[0023] The specific embodiments of the present invention are described below to facilitate understanding of the invention by those skilled in the art. Unless otherwise specified, specific conditions are applied according to conventional conditions or the manufacturer's recommendations. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims. All inventions utilizing the concept of this invention are protected.

[0024] Example 1 A method for preparing a nano-antifungal agent based on dual temperature and pH responses includes the following steps: S1. Preparation of MSN-NH2 support: 100 mg of mesoporous silica (MSN) powder was ultrasonically dispersed in 50 mL of anhydrous ethanol. Then, 500 μL of 3-aminopropyltriethoxysilane (APTES) was added dropwise under nitrogen atmosphere. The mixture was then refluxed under nitrogen atmosphere and 70 °C oil bath for 12 h. The reaction solution was centrifuged at 9000 r / min for 10 min, and the bottom solid precipitate was collected. The precipitate was washed three times with anhydrous methanol to remove unreacted free APTES. Finally, the mixture was vacuum dried at 40 °C to constant weight to obtain the aminated MSN-NH2 support. S2. Preparation of intermediate two (PNIPAM-CHO polymer); S21. Dissolve 5g of N-isopropylacrylamide (NIPAM), 0.08g of azobisisobutyronitrile (AIBN), and 0.056g of mercaptoethanol in 20mL of 1,4-dioxane. Then, bubble nitrogen gas for 20min to completely remove oxygen from the reaction system. Then, react in an oil bath at 68℃ under nitrogen atmosphere for 24h. Finally, cool to room temperature to obtain hydroxyl-terminated intermediate one (PNIPAM-OH polymer). S22. Dissolve 2g of PNIPAM-OH polymer, 0.6g of p-formylbenzoic acid, 0.8g of dicyclohexylcarbodiimide (DCC) and 0.1g of 4-dimethylaminopyridine (DMAP) in 36mL of dichloromethane, and then stir the reaction in the dark for 24h to obtain intermediate two, namely PNIPAM-CHO polymer. S3. Dissolve 100 mg MSN-NH2 support and 500 mg PNIPAM-CHO polymer in 4 mL of dimethyl sulfoxide, and then stir the reaction at 40 °C for 6 h. Centrifuge the reaction solution at 9000 r / min for 10 min, collect the bottom solid precipitate, wash it three times with anhydrous methanol, and finally dry it under vacuum at 40 °C to constant weight to obtain the core-shell structured intermediate tri(PNIPAM-MSN). S4. Mix 50 mg PNIPAM-MSN and 20 mg IPBC antifungal agent in 20 mL of ethanol solution (PBS buffer: anhydrous ethanol = 9:1, v:v). Stir for 72 h under light-protected conditions, then heat to 37 °C and continue stirring for 24 h. The temperature is higher than the minimum critical dissolution temperature of PNIPAM, causing the temperature-sensitive segments of PNIPAM to change from hydrophilic to hydrophobic and collapse spontaneously, physically blocking the mesopore openings on the MSN surface and achieving drug lock-in. Then, centrifuge at 9000 r / min for 10 min, collect the powder, and wash three times with distilled water at 37 °C to remove free IPBC that is only adsorbed on the powder surface and has not entered the mesopores. Finally, freeze-dry at -45 °C for 24 h to obtain the PNIPAM-MSN@IPBC nano antifungal agent.

[0025] Example 2 A method for preparing a nano-antifungal agent based on dual temperature and pH responses includes the following steps: S1. Preparation of MSN-NH2 support: 80 mg of mesoporous silica (MSN) powder was ultrasonically dispersed in 50 mL of tetrahydrofuran. Then, 550 μL of 3-aminopropyltriethoxysilane (APTES) was added dropwise under nitrogen atmosphere. The mixture was then refluxed under nitrogen atmosphere and 75 °C oil bath for 10 h. The reaction solution was centrifuged at 9000 r / min for 10 min, and the bottom solid precipitate was collected. The precipitate was washed three times with anhydrous methanol to remove unreacted free APTES. Finally, the mixture was vacuum dried at 40 °C to constant weight to obtain the aminated MSN-NH2 support. S2. Preparation of intermediate two; S21. Dissolve 7g N,N-diethylacrylamide, 0.05g azobisisobutyronitrile (AIBN) and 0.03g mercaptoethanol in 30mL 1,4-dioxane. Then bubble with nitrogen for 20min to completely remove oxygen from the reaction system. Then react in an oil bath at 65℃ under nitrogen atmosphere for 26h. Finally cool to room temperature to obtain hydroxyl-terminated intermediate one. S22. Dissolve 1g of intermediate one, 0.8g of p-formylbenzoic acid, 1g of dicyclohexylcarbodiimide (DCC) and 0.05g of 4-dimethylaminopyridine (DMAP) in 36mL of N,N-dimethylformamide, and then stir the mixture in the dark for 22h to obtain intermediate two. S3. Dissolve 150 mg MSN-NH2 support and 400 mg intermediate II in 4 mL of dimethyl sulfoxide, and then stir the reaction at 35 °C for 8 h. Centrifuge the reaction solution at 9000 r / min for 10 min, collect the bottom solid precipitate, wash it three times with anhydrous methanol, and finally dry it under vacuum at 40 °C to constant weight to obtain core-shell structured intermediate III. S4. Mix 70 mg of intermediate trioxide and 10 mg of IPBC antifungal agent in 30 mL of ethanol solution (PBS buffer: anhydrous ethanol = 9:1, v:v). Stir for 74 h under light-protected conditions, then heat to 35 °C and continue stirring for 26 h. Centrifuge at 9000 r / min for 10 min, collect the powder, and wash three times with distilled water at 37 °C to remove free IPBC that is only adsorbed on the powder surface and has not entered the mesopores. Finally, freeze-dry at -40 °C for 26 h to obtain the nano antifungal agent.

[0026] Example 3 A method for preparing a nano-antifungal agent based on dual temperature and pH responses includes the following steps: S1. Preparation of MSN-NH2 support: 120 mg of mesoporous silica (MSN) powder was ultrasonically dispersed in 60 mL of anhydrous ethanol. Then, 450 μL of 3-aminopropyltriethoxysilane (APTES) was added dropwise under nitrogen atmosphere. The mixture was then refluxed under nitrogen atmosphere and 65 °C oil bath for 14 h. The reaction solution was centrifuged at 9000 r / min for 10 min, and the bottom solid precipitate was collected. The precipitate was washed three times with anhydrous methanol to remove unreacted free APTES. Finally, the mixture was vacuum dried at 40 °C to constant weight to obtain the aminated MSN-NH2 support. S2. Preparation of intermediate two (PNIPAM-CHO polymer); S21. Dissolve 3g of N-isopropylacrylamide (NIPAM), 0.1g of azobisisobutyronitrile (AIBN), and 0.08g of mercaptoethanol in 20mL of N,N-dimethylformamide. Then, bubble nitrogen gas for 20min to completely remove oxygen from the reaction system. Then, react in an oil bath at 70℃ under nitrogen atmosphere for 22h. Finally, cool to room temperature to obtain hydroxyl-terminated intermediate 1 (PNIPAM-OH polymer). S22. Dissolve 3g of PNIPAM-OH polymer, 0.4g of p-formylbenzoic acid, 0.5g of dicyclohexylcarbodiimide (DCC) and 0.15g of 4-dimethylaminopyridine (DMAP) in 35mL of dichloromethane, and then stir the reaction in the dark for 26h to obtain intermediate two, namely PNIPAM-CHO polymer. S3. Dissolve 50 mg MSN-NH2 support and 600 mg PNIPAM-CHO polymer in 5 mL tetrahydrofuran, and then stir the reaction at 45 °C for 4 h. Centrifuge the reaction solution at 9000 r / min for 10 min, collect the bottom solid precipitate, wash it three times with anhydrous methanol, and finally dry it under vacuum at 40 °C to constant weight to obtain core-shell structured intermediate III (PNIPAM-MSN). S4. Mix 30 mg PNIPAM-MSN and 30 mg IPBC antifungal agent in 40 mL ethanol solution (PBS buffer: anhydrous ethanol = 9:1, v:v). Stir for 70 h under light-protected conditions, then heat to 40 °C and continue stirring for 22 h. Centrifuge at 9000 r / min for 10 min, collect the powder, and wash three times with distilled water at 37 °C to remove free IPBC that is only adsorbed on the powder surface and has not entered the mesopores. Finally, freeze-dry at -50 °C for 22 h to obtain PNIPAM-MSN@IPBC nano antifungal agent.

[0027] Comparative Example 1 The difference between this comparative example and Example 1 is that PNIPAM-MSN in S4 is replaced with mesoporous silica (MSN) mixed with IPBC antifungal agent, while the other implementation conditions are the same as in Example 1, to obtain MSN@IPBC.

[0028] The following experiments were conducted using the PNIPAM-MSN@IPBC nano-antifungal agent prepared in Example 1 and the MSN@IPBC prepared in Comparative Example 1 as samples.

[0029] Experimental Example 1: Detection of Drug Loading Capacity (DLC) and Drug Loading Efficiency (DLE) 1. Standard curve preparation operation IPBC-DMSO standard solutions with concentrations ranging from 0 to 1 mg / L (0, 0.2, 0.4, 0.6, 0.8, and 1 mg / L) were prepared, and UV spectrophotometry was performed at 268 nm. Each concentration was repeated three times, and the average absorbance was recorded. Linear fitting yielded the standard equation y = 0.2537x + 0.0008, with a linear correlation coefficient R0. 2 =0.9933 ( Figure 1 ), used for quantitative detection of total nanoparticle load IPBC.

[0030] 2. Sample testing procedures Weigh 4 mg of MSN@IPBC and PNIPAM-MSN@IPBC samples respectively, and completely disperse them in 4 mL of DMSO solvent. Measure the absorbance of the samples at 268 nm. Substitute the absorbance into the standard curve to calculate the IPBC loading mass inside the samples. The formulas for calculating drug loading (DLC) and drug loading efficiency (DLE) are as follows: ; ; Wherein, W1 is the loaded mass of IPBC in the nano-antifungal agent, g; W2 is the total mass of the nano-antifungal agent, g; and W3 is the mass of IPBC added, g.

[0031] Drug loading of the two groups of samples as follows Figure 2 and Figure 3 As shown, the ungrafted blank MSN directly loaded with IPBC, i.e., MSN@IPBC in Comparative Example 1, had a drug loading of 16.3% and a drug loading rate of 22.3%, indicating a relatively low total amount of effective antifungal agent that could be carried with the same amount of carrier. After PNIPAM grafting modification, the drug loading of PNIPAM-MSN@IPBC prepared in Example 1 increased to 21.0% and the drug loading rate reached 58.1%, achieving the same total effective release of IPBC. The two groups showed significant differences in loading performance. After modification using the method of this invention, the loading performance was significantly improved, the amount of IPBC raw material required was greatly reduced, and the raw material cost was significantly decreased.

[0032] Experimental Example 2: Temperature-Controlled Release Kinetics Test 1. Preparation of standard curves IPBC anhydrous ethanol standard solutions with concentrations ranging from 0 to 1 mg / L (0, 0.2, 0.4, 0.6, 0.8, and 1 mg / L) were prepared, and the absorbance was measured at 268 nm. The linear equation obtained by fitting the data was y = 0.3587x + 0.0041, with a correlation coefficient R0. 2 =0.9993 ( Figure 4 ).

[0033] 2. Release Experiment Procedure Disperse 1 mg of PNIPAM-MSN@IPBC powder in 1 mL of anhydrous ethanol, immerse the entire powder in 4 mL of anhydrous ethanol release medium, and incubate in a constant temperature environment of 25℃, 32℃, and 37℃ for 100 h. Take out 200 μL of release liquid at fixed time intervals and add 200 μL of fresh anhydrous ethanol to maintain the system volume.

[0034] Cumulative drug release, such as Figure 5 As shown, after constant temperature incubation to release equilibrium, the equilibrium drug release was 42.16% at 25℃, 33.72% at 32℃, and only 29.76% at 37℃. The higher the temperature, the lower the equilibrium drug release, indicating a significant high-temperature blocking and drug-locking effect on mesopores. Compared to 25℃, the release of PNIPAM-MSN@IPBC samples at 37℃ decreased by approximately 30%. This is because the present invention uses a thermosensitive polymer of PNIPAM with a critical dissolution temperature (LCST) of 32℃ to modify the MSN carrier. Due to the thermosensitive properties of PNIPAM in PNIPAM-MSN@IPBC, when the ambient temperature is <32℃, the PNIPAM molecular chains hydrophilically expand, and the MSN mesoporous channels are fully open, which is conducive to the full loading of IPBC into the carrier. When the ambient temperature is ≥37℃ (the optimal growth range of Aspergillus niger is 33-37℃), PNIPAM undergoes a hydrophobic phase transition, and the molecular chains collapse tightly to cover the MSN surface, physically blocking all mesoporous channels to form a protective layer. This inhibits premature leakage of IPBC in high-temperature and humid storage environments from the molecular structure level, suppresses premature release of IPBC, and extends the basic protection time of the fabric from the root.

[0035] 3. Dynamic Fitting The drug release kinetics fitting results of PNIPAM-MSN@IPBC at different temperatures (25℃, 32℃, and 37℃) are shown in Table 1 and... Figures 6-8 As shown.

[0036] Table 1. Fitting parameters for drug release kinetics of PNIPAM-MSN@IPBC

[0037] Figures 6-8 The figures show a comparison of drug release kinetic fitting at different temperatures (25℃, 32℃ and 37℃). The black curve represents the pseudo-second-order kinetic model, which has a significantly better fitting accuracy than the pseudo-first-order curve (red curve).

[0038] Experimental Example 3: pH Targeted Release Test 1. Buffer solution preparation process PBS buffer (0.01 mol / L, pH=7.4): Weigh 8.00 g NaCl, 0.20 g KCl, 1.44 g Na2HPO4, and 0.24 g KH2PO4, add to 900 mL of ultrapure water and stir to dissolve. Adjust the pH to 7.40, bring the volume to 1 L with ultrapure water, filter through a 0.22 μm aqueous filter membrane to remove impurities, and store at room temperature away from light.

[0039] MES buffer (0.01 mol / L, pH=5.0): Weigh 1.952 g of MES, add 950 mL of ultrapure water and stir to dissolve. Adjust the pH to 5.00 by slow titration with 1 mol / L NaOH solution. Make up the volume to 1 L with ultrapure water. Filter through a 0.22 μm aqueous filter membrane and store away from light.

[0040] 2. Standard system configuration IPBC gradient standard solutions were prepared using a MES buffer-anhydrous ethanol (1:1, v:v) mixture. Absorbance was measured at 268 nm, and the standard curve equation was obtained by fitting the data: y = 0.0461x + 0.0011, with a correlation coefficient R0. 2 =0.9957 ( Figure 9 ).

[0041] 3. Group incubation operation The experimental group at pH 5.0 consisted of 1 mg PNIPAM-MSN@IPBC powder + 500 μL MES buffer at pH 5.0; the experimental group at pH 7.4 consisted of 1 mg PNIPAM-MSN@IPBC powder + 500 μL PBS buffer at pH 7.4. Both centrifuge tubes were sealed and incubated at 25°C in the dark for 12 hours. Every 3-4 hours, the tubes were removed and vortexed for 30 seconds to reduce nanoparticle sedimentation and aggregation.

[0042] 4. Extraction detection After incubation, add 500 μL of anhydrous ethanol to each centrifuge tube, maintaining a buffer-to-ethanol volume ratio of 1:1. Vortex vigorously for 3 min, then allow to stand at room temperature in the dark for 2 h for extraction, vortexing for 30 s every 30 min to ensure complete drug extraction. Filter the mixture through a 0.22 μm PTFE organic filter, discarding the first 1-2 drops to rinse the filter membrane, and collect the clear filtrate. Zero the filter using the corresponding buffer-ethanol mixture blank, and measure the absorbance at 268 nm. Substitute the absorbance into the standard curve to calculate the released IPBC mass and obtain the cumulative drug release rate.

[0043] Cumulative drug release under different pH conditions, such as Figure 10 As shown, the MSN carrier core and the PNIPAM temperature-sensitive shell are connected by hydrolyzable imine bonds, which possess acid-hydrolyzable properties. When PNIPAM-MSN@IPBC is stored in a normal neutral environment on the fabric (pH=7.4), the imine bond chemical structure is stable, and the cumulative release rate of IPBC within a 12-hour incubation period is only 21.6%. When the mold continuously secretes organic acids and the local microenvironment pH ≤ 5.0, the imine bonds rapidly hydrolyze and break, releasing the PNIPAM layer and triggering IPBC release. The temperature-sensitive barrier fails, and under the same 12-hour incubation conditions, the cumulative release of IPBC can reach 83.5%. This indicates that the release rate of PNIPAM-MSN@IPBC prepared in this invention is much higher in an acidic mold microenvironment than in a neutral storage environment on the fabric. The agent is released only at the mold growth site, significantly reducing ineffective losses in a neutral, mold-free environment. The acid-sensitive targeted drug release effect is significant, and the total consumption of IPBC is significantly reduced under the same anti-mold effect.

[0044] Experiment Example 4: Fabric Mildew Resistance Test 1. Preparation of Aspergillus niger spore suspension Aspergillus niger was spread onto fungal solid agar medium and incubated at 30°C for 5-7 days until a large number of mature black spores appeared on the surface of the plate. 5 mL of sterile physiological saline was added to the plate, and all spores were gently scraped off using an autoclaved spreader. The spore clumps were then vortexed to disperse the spores. The plate was then centrifuged at 5000 rpm for 10 min to remove the supernatant. The precipitate was resuspended in 30 mL of sterile water and vortexed and centrifuged twice more. The final dilution was adjusted to 1.2 × 10⁻⁶. 7 CFU / mL spore suspension is available for use.

[0045] 2. Fabric impregnation finishing process Pure IPBC and the PNIPAM-MSN@IPBC powder prepared in Example 1 were used as antifungal agent samples. Different concentrations of antifungal solutions were prepared (pure IPBC solution group: 150, 300, 450, 600, and 750 mg / L; PNIPAM-MSN@IPBC solution group: 15, 30, 60, 120, and 240 mg / L). Sterilized cotton fabric was then cut into 5cm × 5cm square samples. The fabric samples were completely immersed in the antifungal solutions of different concentrations at room temperature for 30 minutes, then removed and completely air-dried at room temperature. They were then immersed again in the finishing solution, with the fabric repeatedly turned over with tweezers to ensure uniform adsorption, and air-dried again. This immersion-air-drying cycle was repeated 3-5 times until the fabric samples were completely dry, then sealed for later use.

[0046] 3. Inoculation and constant temperature incubation procedures 100 μL of spore suspension was evenly spread onto the entire surface of fungal agar medium. Fabric samples impregnated with different antifungal agents were then flattened onto the surface of the medium, with three parallel samples for each concentration group. All plates were placed in a sealed incubator at 35℃ and observed periodically for mold growth. The antifungal grade was determined according to GB / T 24346-2009, the Grading Standard for Antifungal Efficacy of Textiles.

[0047] After a short-term culture of 7 days, the growth of mold on the fabric surface under different concentrations of free IPBC solution is as follows: Figure 11 As shown in Table 2, the results of the anti-mildew rating are as follows. After 28 days of long-term incubation, the growth of mold on the fabric surface under different concentrations of PNIPAM-MSN@IPBC solution is shown in the table below. Figure 12 As shown in Table 3, the results of the anti-mildew rating are as follows.

[0048] Table 2. Short-term mildew resistance rating of fabrics under different concentrations of free IPBC solution (7 days)

[0049] Table 3. 28-day long-term mildew resistance rating of fabrics under different concentrations of PNIPAM-MSN@IPBC solution

[0050] Table 2 shows that after treating fabrics with 150 mg / L free IPBC solution for 7 days, the mildew resistance level was 3, while after treatment with 300 mg / L solution, the mildew resistance level was 1. Low concentrations resulted in severe mildew growth. Figure 11 Only when the IPBC solution concentration is increased to 450 mg / L or higher can the fabric reach the level 0 mildew prevention standard, and it can only maintain short-term protection for 7 days. Under long-term storage conditions, mildew will re-proliferate in large quantities. This is because IPBC only relies on physical adsorption to adhere to the fabric pores, and it is very easy to desorb and leak under high temperature and high humidity storage conditions, resulting in a significant reduction in long-term mildew prevention ability.

[0051] As shown in Table 3, the antifungal rating of fabrics at concentrations of 15, 30, 60, and 120 mg / L is 1, while the rating at 240 mg / L is 0 throughout the entire process. Only the 240 mg / L concentration group meets the national standard level 0 antifungal rating for the entire 28-day period, thus reducing the total amount of IPBC required for the same long-term protection. Furthermore, 240 mg / L is the minimum effective antibacterial concentration, with a clear boundary for concentration use, facilitating industrial compounding and production.

[0052] In summary, free IPBC requires a solution concentration of at least 450 mg / L to maintain short-term Grade 0 mildew protection for 7 days; this invention only requires a single immersion of the fabric with a 240 mg / L PNIPAM-MSN@IPBC solution, and after continuous high-temperature incubation at 35°C for 28 days, it can maintain the national standard Grade 0 mildew protection throughout the entire process, demonstrating outstanding long-term protection advantages.

Claims

1. A method for preparing a nano-antifungal agent based on dual temperature and pH responses, characterized in that, Includes the following steps: S1. Preparation of MSN-NH2 support: Mesoporous silica powder is dispersed in an organic solvent, followed by the addition of a silane coupling agent under nitrogen atmosphere, and then refluxed at 65-75℃ for 10-14 h under nitrogen atmosphere to obtain MSN-NH2 support; the ratio of mesoporous silica powder to silane coupling agent is 8-12 mg: 45-55 μL; S2. Preparation of intermediate two; S21. Mix acrylamide monomers, initiators, and chain transfer agents at a ratio of 3-7: Dissolved in an organic solvent at a mass ratio of 0.05-0.1:0.03-0.08, and then reacted at 65-70℃ under nitrogen atmosphere for 22-26 hours to obtain intermediate one; S22. Intermediate 1, p-formylbenzoic acid, carbodiimide condensing agent and pyridine nucleophilic catalyst are dissolved in an organic solvent at a mass ratio of 1-3:0.4-0.8:0.5-1:0.05-0.15, and then reacted in the dark for 22-26 hours to obtain intermediate 2. S3. Dissolve the MSN-NH2 support and intermediate two in an organic solvent at a mass ratio of 5-15:40-60, and then stir the reaction at 35-45℃ for 4-8 hours to obtain intermediate three. S4. The intermediate trioxide and the antifungal agent are mixed in an organic solvent at a mass ratio of 3-7:1-3. The mixture is stirred for 70-74 hours under light-protected conditions, then heated to 35-40℃ and stirred for 22-26 hours. Finally, it is freeze-dried to obtain a nano antifungal preparation. The antifungal agent is IPBC.

2. The preparation method of the nano-antifungal agent based on dual temperature and pH response according to claim 1, characterized in that, The organic solvent is anhydrous ethanol, 1,4-dioxane, dichloromethane, dimethyl sulfoxide, tetrahydrofuran, or N,N-dimethylformamide.

3. The preparation method of the nano-antifungal agent based on dual temperature and pH response according to claim 1, characterized in that, The silane coupling agent is an alkoxysilane containing a primary amino group; the initiator is an azo compound; and the chain transfer agent is a thiol compound containing both a mercapto group and a hydroxyl group.

4. The preparation method of the nano-antifungal agent based on dual temperature and pH response according to claim 3, characterized in that, The silane coupling agent is 3-aminopropyltriethoxysilane; the initiator is azobisisobutyronitrile; and the chain transfer agent is mercaptoethanol.

5. The method for preparing the nano-antifungal agent based on dual temperature and pH response according to claim 1, characterized in that, The acrylamide monomer is N-isopropylacrylamide or N,N-diethylacrylamide.

6. The method for preparing the nano-antifungal agent based on dual temperature and pH response according to claim 1, characterized in that, The carbodiimide condensing agent is dicyclohexylcarbodiimide; the pyridine nucleophilic catalyst is 4-dimethylaminopyridine.

7. The method for preparing the nano-antifungal agent based on dual temperature and pH response according to claim 1, characterized in that, The freeze-drying temperature in S4 is -40~-50℃, and the time is 22-26h.

8. A nano-antifungal agent based on dual temperature and pH responses, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the nano-antifungal agent based on dual temperature and pH response as described in claim 8 in the field of fabric antifungal treatment.

10. The application according to claim 9, characterized in that, The concentration of the nano-antifungal agent used is 15-240 mg / L.

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