Nano targeted antibacterial drug and preparation method thereof

Abstract

The invention discloses a nano targeted antibacterial drug and a preparation method thereof. The preparation method comprises the following steps: S1, preparing chitosan modified mesoporous silica nanoparticles; S2, preparing folic acid and chitosan co-modified mesoporous silica nanoparticles; S3, preparing honokiol-loaded mesoporous silica nanoparticles; S4, adding the honokiol-loaded mesoporous silica nanoparticles prepared in S3 into a baicalin PBS (Phosphate Buffer Solution); and sequentially adjusting the pH value of the solution, stirring, centrifugally separating, washing and drying. The nano targeting antibacterial drug entrapped with honokiol and baicalin is prepared by taking mesoporous silica as a nano carrier, folic acid as a targeting agent and chitosan as a hole sealing agent and applying a pH regulation step-by-step drug loading technology, has remarkable antibacterial activity and can kill bacteria, and meanwhile, has remarkable anti-inflammatory activity and can inhibit inflammatory reaction, so that the nano targeting antibacterial drug can be used for preparing the nano targeting antibacterial drug entrapped with honokiol and baicalin. The wound healing capability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of traditional Chinese medicines, and in particular to a nano targeted antibacterial drug and a preparation method thereof. Background Art

[0002] Bacterial infection and inflammatory response are the main factors that hinder wound healing. Bacteria reproduce in the wound to form bacterial biofilms, and lipopolysaccharides released by dead bacteria cause tissue inflammation, which can lead to sepsis and multiple organ failure, seriously endangering life and health. Currently, antibiotics are the main strategy for treating bacterial infections and reducing mortality after severe infections. However, the overuse of antibiotics has led to the emergence of drug-resistant bacteria. Antibiotics can generally only kill floating bacteria, and it is difficult for them to penetrate into the biofilm to kill bacteria in the biofilm, which can easily lead to recurrence of bacterial infection. Therefore, there is an urgent need to develop a new strategy that can simultaneously fight bacteria, remove bacterial biofilms, and fight excessive inflammation induced by dead bacteria to treat bacterial wound infections and promote wound healing. Summary of the invention

[0003] The present invention aims to utilize natural active ingredients of traditional Chinese medicine, mesoporous silica nanoparticles as nanocarriers, folic acid as bacterial targeting agent, chitosan as sealing agent, and pH-adjusted step-by-step drug loading technology to prepare a nano-targeted antibacterial drug encapsulating honokiol and baicalin, which has significant antibacterial and anti-inflammatory activity, inhibits inflammatory response, and enhances wound healing ability.

[0004] The present invention provides a method for preparing a nano targeted antibacterial drug, comprising the following steps:

[0005] S1: Preparation of chitosan-modified mesoporous silica nanoparticles:

[0006] Dissolve chitosan in an acetic acid aqueous solution, then add γ-glycidyloxypropyltrimethoxysilane ethanol solution, react at room temperature in the dark for 24 hours to obtain a mixed solution, disperse an appropriate amount of mesoporous silica nanoparticles in the mixed solution, continue to react at room temperature for 24 hours, and then centrifuge at a high speed of 13000 rpm for 15 minutes, wash with deionized water, and vacuum dry for 24 hours to obtain chitosan-modified mesoporous silica nanoparticles;

[0007] S2: Preparation of folic acid and chitosan co-modified mesoporous silica nanoparticles:

[0008] 25-250 mg of folic acid is added to dimethyl sulfoxide, and after stirring to completely dissolve, 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are added at the same time, and stirred in a dark environment for 2 hours, then 25 mg of chitosan-modified mesoporous silica nanoparticles are slowly added, and the mixture is stirred at room temperature for 24 hours, and then centrifuged at a high speed of 13000 rpm for 15 minutes, washed with ethanol, and vacuum dried for 24 hours to obtain mesoporous silica nanoparticles co-modified with folic acid and chitosan;

[0009] S3: Preparation of mesoporous silica nanoparticles loaded with honokiol:

[0010] Dissolve 25-100 mg of honokiol in anhydrous ethanol, stir at 40°C until completely dissolved, adjust the pH value to 4.0-6.8 with phosphoric acid, then add 50 mg of folic acid and chitosan co-modified mesoporous silica nanoparticles, stir in a water bath for 4 hours under sealed conditions, the water bath temperature is 25-45°C, then vacuum dry to remove ethanol, and obtain a dried substance;

[0011] The dried material was added to an ethanol aqueous solution, vortexed for 1 min, and then centrifuged at a high speed of 13000 rpm for 15 min, washed with ethanol, and vacuum dried for 24 h to obtain mesoporous silica nanoparticles loaded with magnolol;

[0012] S4: Dissolve 50-100 mg of baicalin in PBS buffer and adjust the pH value to 4.0-6.8 with PBS buffer, stir in a water bath until completely dissolved, and the water bath temperature is 25-45°C to obtain a baicalin PBS solution. Add the mesoporous silica nanoparticles loaded with magnolol prepared in S3 to the baicalin PBS solution, stir in a water bath for 4 hours under sealed conditions, and the water bath temperature is 25-45°C. Continue stirring under open conditions until the solution evaporates to dryness, then vacuum dry for 2 hours to obtain a dried sample, add an appropriate amount of PBS buffer solution to the dried sample, vortex for 1 minute, and then high-speed centrifuge at a centrifugal speed of 13000 rpm for 15 minutes, wash with ethanol water, and vacuum dry for 24 hours to obtain a nano-targeted antibacterial drug.

[0013] Furthermore, the weights of folic acid, honokiol and baicalin are 200 mg, 50 mg and 100 mg, respectively.

[0014] Furthermore, in steps S1-S4, the vacuum drying temperature is 35-45°C.

[0015] Furthermore, in steps S3 and S4, the water bath temperature is 40°C.

[0016] Furthermore, in steps S3 and S4, the pH value is 6.3.

[0017] Furthermore, the molecular weight of chitosan is 30,000, and the degree of deacetylation is not less than 85%.

[0018] Furthermore, the particle size of the mesoporous silica nanoparticles is 100 nm to 300 nm.

[0019] The present invention also provides an antibacterial drug prepared by the method for preparing a nano targeted antibacterial drug.

[0020] Beneficial effects of the present invention:

[0021] 1. The nano targeted antibacterial drug of the present invention contains mesoporous silica nanoparticles, baicalin, honokiol, folic acid, chitosan, etc., has significant antibacterial and anti-inflammatory activities, can improve the solubility, stability, drug loading and bacterial targeting rate of the drug, has good biocompatibility and biodegradability, and is safe and non-toxic.

[0022] 2. The Chinese medicinal ingredients in the nano targeted antibacterial drugs provided by the present invention have good synergistic effects. They not only have significant antibacterial activity and kill bacteria, but also have significant anti-inflammatory activity, inhibit inflammatory reactions, and enhance wound healing ability.

[0023] 3. The active ingredients of traditional Chinese medicine are encapsulated and released in a controlled manner by using pH-adjusted step-by-step drug delivery technology and folic acid and chitosan surface modification technology, which improves the stability of the active ingredients. The preparation process is convenient, simple, low-cost and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Figures 1 and 2 are the antibacterial and anti-inflammatory effects of HK, BA and HK-BA; A is the inhibition of HK, BA and HK-BA on S. aureus; B is the inhibition of HK, BA and HK-BA on MRSA; C is the inhibition of TNF-α by Control group, LPS group, HK, BA and HK-BA; D is the inhibition of IL-10 by Control group, LPS group, HK, BA and HK-BA; Control group is the level of inflammatory factors under normal growth of Raw264.7 macrophages, that is, no LPS stimulation and no drug administration; LPS group is the positive control group, which means that LPS stimulation is given but no drug administration (Note: Compared with LPS group, $$P<0.01, $P<0.005; Compared with HK, **P<0.01, *P<0.05; Compared with BA, ##P<0.01, #P<0.05);

[0025] Figure 2The bar graphs are the MIC and MBC of different dosing groups; A is the MIC graph of different dosing groups against S. aureus; B is the MIC graph of different dosing groups against MRSA; C is the MBC graph of different dosing groups against S. aureus; D is the MBC graph of different dosing groups against MRSA;

[0026] Figure 3 : is the acid-responsive release curve of FA-CS-FSN-HK-BA; wherein: A is the in vitro release curve of HK under different pH conditions; B is the in vitro release curve of BA under different pH conditions;

[0027] Figure 4 The figures are the in vivo antibacterial and wound healing experimental figures; A is the time series comparison of wound healing effect between the model group and different drug administration groups; B is the comparison of wound surface area between the model group and different drug administration groups on the 10th day; C is the tissue H&E comparison between the model group and different drug administration groups; D is the tissue Masson staining picture between the model group and different drug administration groups; DETAILED DESCRIPTION

[0028] The above contents of the present invention are further described in detail below with reference to specific implementation modes. However, the protection scope of the present invention is not limited to the implementation modes of the present invention.

[0029] See Table 1 for a comparison of the English abbreviations and substance names.

[0030] Table 1

[0031]

[0032] Traditional antibacterial preparations generally only have antibacterial effects and lack anti-inflammatory effects. They ignore the fact that the large amount of lipopolysaccharide released by dead bacteria can activate immune cells and induce excessive inflammation. It is also difficult for them to penetrate into the biofilm to kill bacteria under the biofilm, leading to the recurrence of bacterial infection and inflammatory response. In addition, traditional antibacterial preparations lack targeting, which makes them easy to cause serious toxic side effects to normal tissues during the treatment of bacterial infections. At present, surface functionalized mesoporous silica nanoparticles have unique advantages in the field of antibacterial applications. The present invention uses mesoporous silica nanoparticles to co-load magnolol with antibacterial activity and baicalin with anti-inflammatory activity, and uses cationic chitosan with good biocompatibility and biological activity as a sealing agent and pH stimulation response valve for the mesoporous silica nanoparticles. At the same time, in order to enhance the targeting of mesoporous silica nanoparticles to bacteria and bacterial biofilms, folic acid is further modified on the chitosan-modified mesoporous silica nanoparticles to construct a pH stimulation-responsive nano antibacterial drug with dual antibacterial and anti-inflammatory effects that can target bacteria and bacterial biofilms. The drug can achieve targeted delivery of bacteria and bacterial biofilms, and release antibacterial drugs in response to the acidic microenvironment of bacteria, thereby providing a new method for treating bacterial infectious diseases caused by drug-resistant bacteria.

[0033] Baicalin is derived from the plant Scutellaria baicalensis, and has multiple effects such as anti-inflammatory, antiviral and antibacterial. Its main anti-inflammatory targets are MAPK14, TNFRSF1A, EGFR, and SELE, and it can directly act on MAPK14 and EGFR to exert anti-inflammatory effects, and can also indirectly act on other targets to exert anti-inflammatory effects; Honokiol is derived from Magnolia officinalis, and its antibacterial mechanism is mainly through blocking the oxidative phosphorylation metabolic pathway and inducing excessive production of reactive oxygen free radicals ROS, leading to an increase in intracellular ROS, thereby inducing oxidative damage to proteins, lipids and DNA to exert antibacterial effects; in addition, excessive ROS will disrupt mitochondrial function, affect respiration, block the tricarboxylic acid TCA cycle, and ultimately inhibit the production of adenosine triphosphate ATP, thereby inducing apoptosis of pathogens; It can be seen that Scutellaria baicalensis and Magnolia officinalis both have significant antibacterial, anti-inflammatory and anti-oxidative stress effects, and have significant antibacterial, biofilm removal, immune response regulation and cytokine storm inhibition effects in mice with severe MRSA infection.

[0034] Nanocarrier technology provides an effective way to deliver antibacterial drugs. Compared with traditional nanocarriers, mesoporous silica nanoparticles have a diameter of 600-1000 m 2 / g and a specific surface area of ​​0.6-1.0cm 3 / g pore volume, more drugs can be loaded on its surface or inside the nanopores, and the pore wall surface has abundant silanol groups, which can be easily chemically modified or modified by silane coupling agents, so as to design different functionalized surfaces. Biodegradable and biocompatible, it is widely used as a nanocarrier for drug delivery. Therefore, due to its porosity, easy functional modification and good biocompatibility, mesoporous silica nanoparticles can provide an effective nanocarrier for antibacterial infectious diseases. Bacterial biofilms have a microenvironment different from that of normal tissues, such as acidic pH, hypoxia, high glutathione concentration, overexpressed specific enzymes, etc. Chitosan is a rare alkaline polysaccharide in natural polymers, insoluble in water and organic solvents, soluble in dilute acid with pH <6.3, and is often used as a pH-responsive sensitive material, while folic acid is a precursor for bacterial nucleic acid synthesis, and folic acid can be used as a ligand targeting bacteria. Therefore, the present invention uses mesoporous silica nanoparticles to co-load magnolol with antibacterial activity and baicalin with anti-inflammatory activity, and uses cationic chitosan with good biocompatibility and biological activity as a sealing agent and pH stimulation response valve for the mesoporous silica nanoparticles. At the same time, in order to enhance the targeting of mesoporous silica nanoparticles to bacteria and bacterial biofilms, folic acid is further modified on the chitosan-modified mesoporous silica nanoparticles to construct a pH stimulation-responsive nano antibacterial drug with dual antibacterial and anti-inflammatory effects and capable of targeting bacteria and bacterial biofilms.

[0035] Embodiment 1:

[0036] S1: Preparation of CS-FSN:

[0037] 1.0 g of chitosan with a molecular weight of 30,000 and a deacetylation degree of not less than 85% was dissolved in 25 mL of an acetic acid aqueous solution with a mass concentration of 2%, and then 2.5 mL of a γ-glycidyloxypropyltrimethoxysilane ethanol solution with a mass concentration of 98% was added, and the mixture was reacted at room temperature in the dark for 24 hours to obtain a mixed solution, 125 mg of FSN was dispersed in the mixed solution, and the mixture was reacted at room temperature for 24 hours, and then centrifuged at a high speed of 13,000 rpm for 15 minutes, washed with deionized water, and dried in vacuo at 37°C for 24 hours to obtain CS-FSN;

[0038] S2: Preparation of FA-CS-FSN:

[0039] 200 mg of folic acid was added to 5.0 mL of 99.5% dimethyl sulfoxide, stirred to completely dissolve, and then 100 mg of 98% 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride and 100 mg of 98% N-hydroxysuccinimide were added for activation, stirred in a dark environment for 2 h, and then 25 mg of CS-FSN was slowly added, stirred at room temperature for 24 hours, and then centrifuged at high speed at a speed of 13000 rpm for 15 min, washed with ethanol, and dried in vacuo at 40°C for 24 h to obtain FA-CS-FSN;

[0040] S3: Preparation of FA-CS-FSN-HK:

[0041] 50 mg of honokiol was dissolved in 5 mL of anhydrous ethanol, stirred at 40°C until completely dissolved, and the pH value was adjusted to 6.3 with phosphoric acid, and then 50 mg of FA-CS-FSN was added, and the mixture was stirred in a water bath at 40°C for 4 hours under sealed conditions, and then vacuum dried to remove the ethanol to obtain a dried substance;

[0042] The dried material was added to 2 mL of an ethanol-water solution prepared by mixing anhydrous ethanol and ultrapure water in a ratio of 1:2, vortexed for 1 min, and then centrifuged at a high speed of 13,000 rpm for 15 min, washed with ethanol, and vacuum dried at 40°C for 24 h to obtain FA-CS-FSN-HK;

[0043] S4: 100 mg of baicalin was dissolved in 0.2 mol / mL PBS buffer and the pH value was adjusted to 6.3 with PBS buffer. The mixture was stirred in a 40°C water bath until completely dissolved to obtain a baicalin PBS solution. The FA-CS-FSN-HK prepared in S3 was added to the baicalin PBS solution. The mixture was stirred in a 40°C water bath for 4 hours under sealed conditions. The mixture was stirred in an open air condition until the solution evaporated to dryness. The mixture was dried in a vacuum drying oven at 37°C for 2 hours. Then, 2 mL of the above PBS buffer solution was added to the dried sample. The mixture was vortexed for 1 minute and then centrifuged at high speed at a speed of 13,000 rpm for 15 minutes. The mixture was washed with ethanol water and vacuum dried at 37°C for 24 hours to obtain FA-CS-FSN-HK-BA.

[0044] The preparation process of FSN in this embodiment is as follows: 100 mL of anhydrous ethanol, 25 mL of distilled water, 3.5 mL of ammonia water with a mass concentration of 25%-28% and 0.563 mL of ethylenediamine solution with a mass concentration of 99% are placed in a conical flask and vigorously stirred in an oil bath at 60°C; then, 1.03 g of 3-aminophenol, 1.25 mL of formaldehyde solution with a mass concentration of 37%-48%, and 3.9 mL of tetraethyl orthosilicate with a mass concentration of 98% are added respectively, and the stirring reaction is continued for 5 hours, and then high-speed centrifugation is performed at a centrifugal speed of 12000 rpm for 15 minutes, washed with ethanol, vacuum dried at 37°C for 24 hours, and after drying, calcined at 550°C for 6 hours to obtain FSN, preferably; the particle size of FSN is 100nm~300nm.

[0045] Examples 2-7 and Comparative Example 1: Compared with Example 1, the difference is that the weights of folic acid, honokiol and baicalin are as shown in Table 2:

[0046] Table 2 Weight table of folic acid, honokiol and baicalin, unit is mg:

[0047] FA HK BA Example 1 200 50 100 Example 2 25 50 50 Example 3 75 75 100 Example 4 100 75 75 Example 5 150 100 100 Example 6 250 50 100 Example 7 200 75 125 Comparative Example 1 250 25 50

[0048] Table 3 Drug loading rates of Examples 1-7 and Comparative Example 1:

[0049]

[0050]

[0051] It can be seen from Tables 2 and 3 that in Comparative Example 1, when the weight of HK is 25 mg and the weight of BA is 50 mg, the drug loading rate is only 15.02%, and the drug loading rate increases with the increase of the weight of HK and BA; in Example 1, when the masses of HK and BA are 50 mg and 100 mg respectively, the drug loading capacity of FSN for the two is the largest, and the drug loading rate does not change significantly when the dosage is further increased on the basis of Example 1; in Example 1, when the weight of FA is 200 mg, the effect on the entry of drug molecules into the mesoporous channels is small, and in Example 6, when the weight of FA is 250 mg, the drug loading rate decreases, indicating that excessive FA may affect the entry of drugs into the mesoporous channels and lead to reduced drug loading performance.

[0052] Examples 8-12 and Comparative Example 2: Compared with Example 1, the difference is that in steps S3 and S4, the pH value is as shown in Table 3:

[0053] Table 4 Effect of pH value on drug loading rate

[0054]

[0055]

[0056] The effect of pH on drug loading rate was measured by HPLC, as shown in Table 4. When pH ≤ 6.3, FA-CS-FSN has a higher drug loading rate for HK and BA; when pH > 6.3, the drug loading rate decreases, which may be due to the partial closure of the pores of the nanoparticles caused by pH. When pH < 5.0, FA-CS-FSN has little effect on the drug loading rate of HK, but has a great effect on the drug loading rate of BA, which may be caused by the reduced solubility of BA under acidic conditions. It can be seen that too low pH will lead to a decrease in the drug loading rate of BA.

[0057] Embodiments 13-16: Compared with Embodiment 1, the difference is that in steps S3 and S4, the water bath temperature is as shown in Table 5:

[0058] Table 5 Effect of water bath temperature on drug loading rate

[0059] Water bath temperature HK drug loading rate BA drug loading rate Example 1 40℃ 22.27％±0.04％ 42.03％±0.26％ Embodiment 13 25℃ 16.28％±0.57％ 34.78％±0.51％ Embodiment 14 30℃ 17.95％±0.35％ 37.54％±0.38％ Embodiment 15 35℃ 19.35％±0.86％ 40.26％±0.47％ Example 16 45℃ 19.53％±0.53％ 35.25％±0.29％

[0060] It can be seen from Table 5 that the loading rate of the nanoparticles for the two drugs is low at 25°C. The main reason is that the drug solubility is relatively low at room temperature and the movement of drug molecules in the solution at room temperature is slow, resulting in relatively less drug adsorbed on the nanoparticles. When the temperature is 40°C, the two drugs have a higher loading rate; when the temperature is 45°C, the loading rates of the two drugs decrease, which may be due to the instability of HK and BA and oxidative degradation.

[0061] Evaluation of the antibacterial and anti-inflammatory effects of HK, BA and HK-BA: The inhibitory effects of HK, BA and HK-BA on S. aureus and MRSA were evaluated by inhibition curves, and the anti-inflammatory effects were evaluated by ELISA.

[0062] like Figure 1 As shown in A and B, when the HK concentration was ≤48ug / mL, it showed obvious antibacterial effect against S. aureus and MRSA, while BA showed no antibacterial activity. HK-BA could enhance the antibacterial effect.

[0063] Raw264.7 macrophages were seeded in 24-well culture plates and grown at a cell density of 1 × 10 5 cells / well, the seeded cells were placed in a cell culture incubator for 24 hours, and then 1ug / mL lipopolysaccharide solution was added to stimulate the cells to construct a cell inflammation model and evaluate the anti-inflammatory effect of HK-BA. Figure 1 As shown in Figures C and D, HK-BA can significantly reduce TNF-α and increase IL-10 levels, thereby exerting an anti-inflammatory effect.

[0064] Antibacterial performance comparison: The antibacterial performance was evaluated by the minimum inhibitory concentration MIC and the minimum bactericidal concentration MBC:

[0065] Table 6 Minimum inhibitory concentration (μg / mL) of different drug groups

[0066]

[0067] Table 7 Minimum bactericidal concentrations (μg / mL) in different dosing groups

[0068] sample S. aureus MRSA HK 265 256 FA-CS-FSN-HK 128 128 FA-CS-FSN-HK-BA 96 96

[0069] pass Figure 2 As can be seen from Tables 6 and 7, FA-CS-FSN-HK and FA-CS-FSN-HK-BA can significantly reduce the MIC values ​​and MBC values ​​of S. aureus and MRSA, and FA-CS-FSN-HK-BA can enhance the antibacterial effect of S. aureus and MRSA.

[0070] Evaluation of acid-responsive release behavior of FA-CS-FSN-HK-BA: The acid-responsive release behavior of FA-CS-FSN-HK-BA was evaluated by in vitro release, simulating the in vitro release behavior under the conditions of bacterial microenvironment pH of 5.0, chitosan isoelectric point pH of 6.3, and normal physiological environment pH of 7.4.

[0071] like Figure 3 As shown in the figure: A is the in vitro release curve of HK under different pH conditions; B is the in vitro release curve of BA under different pH conditions; when the pH value is 7.4, 48.79% of HK is released within 84 hours, and 29.26% of BA is released within 12 hours; when the pH value is 6.3, 75.08% of HK is released within 84 hours, and 89.30% of BA is released within 12 hours; when the pH value is 5.0, 76.22% of HK is released within 84 hours, and 94.20% of BA is released within 12 hours; when the pH value is <6.3, HK and BA can be effectively released, and with the increase of pH value, the cumulative release of drugs decreases, indicating that FA-CS-FSN-HK-BA has acid-responsive release behavior and can release loaded drugs in response to the wound bacterial infection microenvironment.

[0072] Evaluation of FA-CS-FSN-HK-BA in promoting wound healing:

[0073] A bacterial wound infection model group was established in the abdomen of SD rats. First, the rats were adaptively fed in an SPF environment for one week, and anesthetized by intraperitoneal injection of 2% sodium pentobarbital at 0.2 mL / 100 g. After the rats were fully anesthetized, they were shaved with a small animal trimmer, and then completely depilated with a depilatory cream. The whole process was performed under a sterile environment. After the rats were completely depilated, a circular full-thickness skin wound with a diameter of 8 mm was made on the abdomen of the rats using a skin punch the next day. 50 uL of 5x108 A mixed bacterial solution of S. aureus and MRSA at CFU / mL was dripped onto the wound surface for inoculation.

[0074] Then, 50uL of 100ug / mL FA-CS-FSN-HK-BA solution was administered daily to wounds infected with a mixed bacterial solution of S. aureus and MRSA. The FA-CS-FSN-HK-BA solution was prepared using sterile saline. The healing of the wounds of SD rats was observed at different treatment time points (0 day, 1 day, 3 days, 5 days, 7 days, and 10 days) and photographed and recorded. The dynamic healing process of the wounds over time was constructed using ImageJ software based on real-time wound photographs to evaluate the healing effect of FA-CS-FSN-HK-BA solution on bacterially infected wounds. Figure 4 As shown, the wound area in the model group was always larger, with yellow pus and difficulty in healing; while the wound healing effect in the FA-CS-FSN-HK-BA group was significantly faster than that in the HK and BA groups.

[0075] After the treatment, wound skin tissue was collected for H&E and Masson staining and histological analysis. Figure 4 As shown, the H&E and Masson staining results of the wound skin tissue revealed that the model group had more inflammatory cells, the wound was not closed, and the skin tissue had less re-epithelialization. The FA-CS-FSN-HK-BA group had the smallest wound, intact epidermis, and continuous epithelium, more collagen deposition, and better treatment effect. The main reason is that FA-CS-FSN-HK-BA has bacterial targeting and achieves dual effects of antibacterial and anti-inflammatory, thereby accelerating wound repair.

Claims

1. A method for preparing a nano targeted antibacterial drug, characterized in that: The following steps are involved: S1: Preparation of chitosan-modified mesoporous silica nanoparticles: Dissolve chitosan in an acetic acid aqueous solution, then add γ-glycidyloxypropyltrimethoxysilane ethanol solution, react at room temperature in the dark for 24 hours to obtain a mixed solution, disperse an appropriate amount of mesoporous silica nanoparticles in the mixed solution, continue to react at room temperature for 24 hours, and then centrifuge at a high speed of 13000 rpm for 15 minutes, wash with deionized water, and vacuum dry for 24 hours to obtain chitosan-modified mesoporous silica nanoparticles; S2: Preparation of folic acid and chitosan co-modified mesoporous silica nanoparticles: 25-250 mg of folic acid was added to dimethyl sulfoxide, and after stirring to completely dissolve, 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added at the same time, and stirred in a dark environment for 2 hours. Then, 25 mg of chitosan-modified mesoporous silica nanoparticles were slowly added, and stirred at room temperature for 24 hours, and then centrifuged at a high speed of 13000 rpm for 15 minutes, washed with ethanol, and vacuum dried for 24 hours to obtain folic acid and chitosan co-modified mesoporous silica nanoparticles; S3: Preparation of mesoporous silica nanoparticles loaded with honokiol: Dissolve 50-100 mg of honokiol in anhydrous ethanol, stir at 40°C until completely dissolved, adjust the pH value to 4.0-6.8 with phosphoric acid, then add 50 mg of mesoporous silica nanoparticles co-modified with folic acid and chitosan, stir in a water bath for 4 hours under sealed conditions, the water bath temperature is 25-45°C, then vacuum dry to remove ethanol, and obtain a dried substance; The dried material was added to an ethanol aqueous solution, vortexed for 1 min, and then centrifuged at a high speed of 13000 rpm for 15 min, washed with ethanol, and vacuum dried for 24 h to obtain mesoporous silica nanoparticles loaded with magnolol; S4: Dissolve 50-100 mg of baicalin in PBS buffer and adjust the pH value to 4.0-6.8 with PBS buffer, stir in a water bath until completely dissolved, and the water bath temperature is 25-45°C to obtain a baicalin PBS solution. Add the mesoporous silica nanoparticles loaded with magnolol prepared in S3 to the baicalin PBS solution, stir in a water bath for 4 hours under sealed conditions, and the water bath temperature is 25-45°C. Continue stirring under open conditions until the solution evaporates to dryness, then vacuum dry for 2 hours to obtain a dried sample, add an appropriate amount of PBS buffer solution to the dried sample, vortex for 1 minute, and then high-speed centrifuge at a centrifugal speed of 13000 rpm for 15 minutes, wash with ethanol water, and vacuum dry for 24 hours to obtain a nano-targeted antibacterial drug.

2. The method for preparing a nano targeted antibacterial drug according to claim 1, characterized in that: The weights of folic acid, honokiol and baicalin are 200 mg, 50 mg and 100 mg respectively.

3. The method for preparing a nano targeted antibacterial drug according to claim 1, characterized in that: In steps S1-S4, the vacuum drying temperature is 35-45°C.

4. The method for preparing a nano targeted antibacterial drug according to claim 1, characterized in that: In steps S3 and S4, the water bath temperature is 40°C.

5. The method for preparing a nano targeted antibacterial drug according to claim 1, characterized in that: In steps S3 and S4, the pH value is 6.

3.

6. The method for preparing a nano targeted antibacterial drug according to claim 1, characterized in that: The molecular weight of chitosan is 30,000, and the degree of deacetylation is not less than 85%.

7. The method for preparing a nano targeted antibacterial drug according to claim 1, characterized in that: The particle size of mesoporous silica nanoparticles is 100nm~300nm.

8. An antibacterial drug prepared according to the method for preparing a nano-targeted antibacterial drug according to claim 1.

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