A Fe3O4@PDA-MnO2 nanomaterial, its preparation method and application

Abstract

The present invention relates to a Fe3O4@PDA-MnO2 nanomaterial and its preparation method and application, belonging to the field of biomedical technology. The Fe3O4@PDA-MnO2 nanomaterial of the present invention exhibits excellent photothermal performance and mimetic peroxidase (POD) activity, and its catalytic activity is enhanced under NIR irradiation. Fe3O4@PDA-MnO2 has a bactericidal rate of up to 99% against Gram-positive bacteria, Gram-negative bacteria, and Gram-variable bacteria, and good performance in destroying biofilm formation. In vitro and BV mouse model experiments show that Fe3O4@PDA-MnO2 combined with NIR irradiation significantly reduces vaginal inflammation caused by bacterial infection of BV due to its synergistic antibacterial effect, and is superior to the positive control drug.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedicine. Specifically, it relates to a Fe3O4@PDA-MnO2 nanomaterial, a preparation method thereof and an application thereof. Background Art

[0002] Bacterial vaginosis (BV) affects up to 29% of women globally. It is characterized by vaginal flora imbalance, a decrease in the number of probiotics (lactobacilli), and an increase in the number of pathogenic bacteria, which leads to increased vaginal discharge and a "fishy smell" - like odor, seriously affecting women's health and quality of life. Untreated BV can lead to early spontaneous abortion and increase the susceptibility to sexually transmitted infections. The pathogenesis of BV is multifactorial. The factors affecting the risk of BV occurrence are mainly divided into 4 categories: intrinsic factors (race and genetics), sexual activity (sexual partners, sexually transmitted infections, condom use), hormones (menstrual cycle, intrauterine device, estrogen level, oral contraceptives), and lifestyle. Currently, the standard treatment for BV is oral or intravaginal administration of antibacterial drugs, usually metronidazole or clindamycin, with a relatively high recurrence rate. The recurrence rate within 1 month after the initial treatment is 20% - 30%, and the recurrence rate within 12 months is 58%. Since the use of the above drugs will lead to a decrease in vaginal probiotics (lactobacilli), BV is prone to recurrence. At the same time, antibiotic resistance is also one of the main reasons for the poor treatment effect of BV. To solve the treatment problem of BV, it is urgent to develop new antibacterial substitutes different from the traditional antibacterial mechanism of antibiotics, overcome bacterial resistance, and not affect the population abundance of vaginal probiotics (lactobacilli) and the vaginal microecological environment.

[0003] Nanozymes, nanomaterials with mimetic enzyme catalytic properties, have recently emerged as a novel antibacterial therapeutic agent, mainly relying on their unique ability to produce toxic products, which can effectively disrupt bacterial biofilms. Among the various treatment methods, nanozyme-photothermal therapy (NPT) shows great application potential in anti-infection treatment. It can overcome drug resistance, reduce the drug dosage, and avoid potential systemic side effects, and is considered a promising alternative strategy to antibiotic treatment for anti-infection. During the anti-infection treatment process, the nanozyme-photothermal antibacterial platform can catalyze low-concentration exogenous hydrogen peroxide (H2O2) to produce highly toxic hydroxyl radicals (·OH), resulting in protein denaturation of the cell membrane. Once near-infrared light (NIR) is introduced, the nanozyme-photothermal antibacterial platform can rapidly convert light energy into heat energy at the infection site, playing the role of a "nanoknife" and further causing the death of damaged bacteria through physical cutting. Utilizing the synergistic effect between the nano-catalytic activity and photothermal effect of the nanozyme-photothermal agent, NPT can achieve excellent anti-infection treatment effects by rapidly and effectively killing pathogens. Summary of the Invention

[0004] To overcome the problems existing in the background technology, the present invention designs an iron ion-poly(dopamine) coordinated MnO2 loaded (Fe3O4@PDA-MnO2) nanomaterial, which exhibits excellent photothermal performance and mimetic peroxidase (POD) activity, and its catalytic activity is enhanced under NIR irradiation. Fe3O4@PDA-MnO2 has satisfactory bactericidal and biofilm formation-disrupting properties against Gram-positive bacteria, Gram-negative bacteria, and Gram-variable bacteria, and this material can combine with near-infrared (NIR) nanozyme-photothermal therapy for the treatment of bacterial vaginitis (BV).

[0005] To achieve the above object, the present invention is realized through the following technical solutions:

[0006] The preparation method of the Fe3O4@PDA-MnO2 nanomaterial includes the following steps:

[0007] (1) Mix ethylene glycol and deionized water, and then add ammonia water and mix well;

[0008] (2) Add a dopamine solution to the mixture in step (1) and stir evenly;

[0009] (3) Slowly drop a ferric nitrate solution into step (2) and react at 50-70 °C for 12-15 h; the molar ratio of dopamine to ferric nitrate is 1:5-7.

[0010] (4) After cooling, centrifuge and wash alternately with ethanol and water 3 - 4 times, and obtain Fe3O4@PDA nanomaterials after vacuum drying;

[0011] (5) Take the Fe3O4@PDA prepared in step (4) and KMnO4 and ultrasonically disperse them in deionized water (the mass ratio of Fe3O4@PDA to KMnO4 is 1:1 - 1.5), then stir at room temperature for 1 - 1.5 h, centrifuge, and wash with deionized water 3 - 4 times, and obtain Fe3O4@PDA-MnO2 nanomaterials after vacuum drying.

[0012] The present invention also includes the Fe3O4@PDA-MnO2 nanomaterials obtained by the above preparation method.

[0013] The application of the Fe3O4@PDA-MnO2 nanomaterials of the present invention in the preparation of drugs for treating vaginitis.

[0014] The present invention also provides a hydrogel comprising Fe3O4@PDA-MnO2 nanomaterials.

[0015] The preparation method of the hydrogel containing Fe3O4@PDA-MnO2 nanomaterials described above includes the following steps:

[0016] (1) Stir and dissolve 0.5 - 1.0 g of chitosan in 10 - 15 mL of acetic acid aqueous solution with a mass concentration of 1%, add 10 - 20 mg of Fe3O4@PDA-MnO2, and stir for 10 - 20 min to obtain solution A;

[0017] (2) Add 0.6 - 0.8 g of sodium alginate to 12 - 15 mL of glycerol, and stir for 1 - 1.5 h to obtain solution B;

[0018] (3) Mix solution A and solution B, add 200 - 300 μL of 20 mg / mL calcium chloride solution under stirring, and continue to stir for 10 - 20 min to obtain Fe3O4@PDA-MnO2 hydrogel.

[0019] The application of the hydrogel in the preparation of drugs for treating vaginitis.

[0020] The beneficial effects of the present invention:

[0021] The Fe3O4@PDA-MnO2 nanomaterials synthesized by the present invention have excellent peroxidase-like activity and photothermal properties. Under near-infrared irradiation, the peroxidase-like activity of Fe3O4@PDA-MnO2 is greatly improved. The concentration of Fe3O4@PDA-MnO2 is 20 μg / mL, 1.0 W / cm 2When irradiated with 808 nm NIR for 10 min, the bactericidal rate against Gram-positive bacteria, Gram-negative bacteria, and Gram-variable bacteria is greater than 99%, and it can disrupt biofilm formation, with good biocompatibility and low toxicity.

[0022] In vitro and BV mouse model experiments show that Fe3O4@PDA-MnO2 hydrogel combined with NIR irradiation significantly reduces vaginal inflammation caused by bacterial infection in BV due to its synergistic antibacterial effect, and is superior to the positive control drug metronidazole. Brief Description of the Drawings

[0023] Figure 1 It is the TEM image of Fe3O4@PDA-MnO2 prepared by the present invention;

[0024] Figure 2 It is the high-resolution XPS spectra of (a) Fe 2p and (b) Mn 2p of Fe3O4@PDA-MnO2 prepared by the present invention;

[0025] Figure 3 It is the ultraviolet absorption spectra of Fe3O4@PDA-MnO2 at different concentrations;

[0026] Figure 4 It is Fe3O4@PDA-MnO2 at different concentrations, irradiated with 1.0 W / cm 2 、808 nm for 10 min to obtain the temperature-time curve;

[0027] Figure 5 It is the infrared thermal image of Fe3O4@PDA-MnO2 (100 μg / mL) under irradiation of 1.0 W / cm 2 、808 nm;

[0028] Figure 6 It is the comparison chart of ultraviolet absorption spectra of Fe3O4@PDA-MnO2+H2O2+TMB under irradiation of 1.0 W / cm 2 、808 nm ultraviolet light for 10 min, natural light irradiation, and no irradiation;

[0029] Figure 7 It is the Michaelis-Menten equation of Fe3O4@PDA-MnO2 under fixed H2O2 without light;

[0030] Figure 8 It is the Michaelis-Menten equation of Fe3O4@PDA-MnO2 under fixed TMB without light;

[0031] Figure 9 It is the Michaelis-Menten equation of Fe3O4@PDA-MnO2 under fixed H2O2 with light (irradiated with 1.0 W / cm 2 、808 nm for 10 min);

[0032] Figure 10 is the Michaelis-Menten equation of Fe3O4@PDA-MnO2 under fixed TMB with light illumination (1.0 W / cm 2 , irradiated with 808 nm for 10 min);

[0033] Figure 11 is the effect of different concentrations of Fe3O4@PDA-MnO2 on the survival rates of HUVECs cells and Hep G2 cells at 24 h and 48 h;

[0034] Figure 12 is the antibacterial performance of different groups of Fe3O4@PDA-MnO2 against different pathogenic bacteria under 808 nm infrared light irradiation and without irradiation; where: I: blank control group; II: Fe3O4@PDA-MnO2; III: Fe3O4@PDA-MnO2 + H2O2; IV: Fe3O4@PDA-MnO2 + H2O2 + NIR;

[0035] Figure 13 is to evaluate the anti-biofilm activity of Fe3O4@PDA-MnO2 against different pathogenic bacteria under 808 nm infrared light irradiation and without irradiation by CV staining method;

[0036] Figure 14 is the antibacterial SEM images of different pathogenic bacteria treated with Fe3O4@PDA-MnO2 under 808 nm infrared light irradiation; where: I is the SEM images of various pathogenic bacteria; II is Fe3O4@PDA-MnO2 + H2O2 + NIR;

[0037] Figure 15 is for the nanozyme gel treatment effect of the mouse G. vaginalis vaginitis model in this Example 2, where: I is the healthy group; II is the blank group; III is the Fe3O4@PDA-MnO2 hydrogel treatment group; IV is the Fe3O4@PDA-MnO2 hydrogel + H2O2 treatment group; V is the Fe3O4@PDA-MnO2 hydrogel + H2O2 + NIR treatment group; VI is the metronidazole treatment group;

[0038] Figure 16 is the diagram of the appearance changes of the reproductive systems of the mice in each group of Example 2, and the grouping of I-VI is the same as Figure 12 ;

[0039] Figure 17 is the diagram of the changes in inflammatory cytokines of the mice in each group of Example 2 before and after nanozyme gel treatment, and the grouping of I-VI is the same as Figure 15 ;

[0040] Figure 18It is the histopathological staining diagram of the vaginal inflammation tissue of the mouse model in Example 2, where: I is the healthy group; II is the blank group; II is the Fe3O4@PDA-MnO2 hydrogel + H2O2 + NIRI treatment group. Detailed implementation manners

[0041] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present invention.

[0042] The preparation method of the iron ion-polydopamine coordination-loaded MnO2 (Fe3O4@PDA-MnO2) nanomaterial includes the following steps:

[0043] (1) Mix 16 - 20 mL of ethylene glycol with 10 - 12 mL of deionized water, add 3 - 4 mL of ammonia water with a volume ratio of 28%, stir at 60 °C for 10 - 15 min, add 10 - 15 mL of 50 mg / mL dopamine solution, and after stirring evenly, slowly drop 10 - 15 mL of 18 mg / mL Fe(NO3)3·9H2O into the above mixed solution, react at 60 °C for 12 - 15 h, cool and then centrifuge, and wash alternately with ethanol and water 3 - 4 times, and obtain Fe3O4@PDA nanomaterial after vacuum drying;

[0044] (2) Take 100 - 150 mg of Fe3O4@PDA prepared in step (1) and 100 - 150 mg of KMnO4 obtained by the above preparation, ultrasonically disperse them in 25 - 40 mL of deionized water, then stir at room temperature for 1 - 1.5 h, centrifuge, and wash with deionized water 3 - 4 times, and obtain Fe3O4@PDA-MnO2 nanozyme after vacuum drying;

[0045] (3) Stir and dissolve 0.5 - 1.0 g of chitosan in 10 - 15 mL of acetic acid aqueous solution with a mass concentration of 1%, add 10 - 20 mg of Fe3O4@PDA-MnO2, and stir for 10 - 20 min as solution A; add 0.6 - 0.8 g of sodium alginate to 12 - 15 mL of glycerol, and stir for 1 - 1.5 h as solution B; mix solution A and solution B, add 200 - 300 μL of 20 mg / mL calcium chloride solution under stirring, and continue to stir for 10 - 20 min to obtain Fe3O4@PDA-MnO2 hydrogel.

[0046] In order to illustrate the present invention more clearly, the following examples are used for detailed description.

[0047] Example 1

[0048] A method for preparing iron ion-polydopamine coordinated and loaded MnO2 (Fe3O4@PDA-MnO2) nanomaterials includes the following steps:

[0049] (1) Mix 16 mL of ethylene glycol with 12 mL of deionized water, add 3 - 4 mL of ammonia water with a volume ratio of 28%, stir at 60 °C for 15 min, add 12 mL of 50 mg / mL dopamine solution, and after stirring evenly, slowly drop 12 mL of 18 mg / mL Fe(NO3)3·9H2O into the above mixed solution, react at 60 °C for 12 h, centrifuge after cooling, and wash alternately with ethanol and water 3 times, and obtain Fe3O4@PDA nanomaterials after vacuum drying.

[0050] (2) Take 150 mg of Fe3O4@PDA prepared in step (1) and 150 mg of KMnO4, ultrasonically disperse them in 40 mL of deionized water, then stir at room temperature for 1.2 h, centrifuge, and wash with deionized water 3 times, and obtain Fe3O4@PDA-MnO2 nanomaterials after vacuum drying.

[0051] Figure 1 This is the TEM image of Fe3O4@PDA-MnO2 obtained in this example. The TEM image shows that the Fe3O4@PDA-MnO2 nanomaterials present a chrysanthemum-like morphology with an average diameter of 50 - 100 nm.

[0052] Figure 2 These are the high-resolution XPS spectra of (a) Fe 2p and (b) Mn 2p of Fe3O4@PDA-MnO2. From the 710.1 eV (Fe 3 / 2 and Fe2p 1 / 2 ), and 723.5 eV (Fe 2+ ), the coexistence of Fe 3+ and Fe 2+ and Fe 3+ is determined (a graph of Figure 2 ); the high-resolution Mn 2p spectrum (b graph of Figure 2 ) shows two peaks at 640.9 and 652.9 eV, corresponding to Mn 2p 3 / 2 and Mn 2p 1 / 2 respectively, indicating the formation of manganese dioxide.

[0053] Photothermal performance evaluation of Fe3O4@PDA-MnO2 nanomaterials:

[0054] To evaluate the NIR-triggered photothermal performance of Fe3O4@PDA-MnO2 nanomaterials, the temperature change of the nanomaterial solution under 808 nm NIR laser irradiation was measured. The ultraviolet-visible absorption spectra of Fe3O4@PDA-MnO2 solutions with different concentrations were detected (see Figure 3 ), and it can be seen from Figure 3 that as the concentration of Fe3O4@PDA-MnO2 nanomaterials increased (0 - 200 μg / mL), the absorbance at 808 nm (0.001 - 0.921) increased accordingly. This result indicates that the absorption of Fe3O4@PDA-MnO2 for near-infrared light (808 nm) is concentration-dependent, which prompted us to further explore the photothermal performance of Fe3O4@PDA-MnO2 at different concentrations. Next, we continued to study the photothermal effect of Fe3O4@PDA-MnO2 because of its enhanced absorption in the near-infrared region. As expected, the temperature of Fe3O4@PDA-MnO2 (200 μg / mL) increased significantly from 22.6 °C to 62.2 °C, and was positively correlated with the concentration, while the water only increased by 6.9 °C after 10 min of light irradiation ( Figure 4 ). At the same time, the temperature change of the nanozyme solution under 808 nm near-infrared laser irradiation was monitored by an infrared thermal imaging camera (attached Figure 5 ). The experimental results showed that the temperature change in Fe3O4@PDA-MnO2 (200 μg / mL) depended on the time gradient, and the temperature reached 64.8 °C within 10 min.

[0055] Evaluation of the peroxidase-like nanozyme activity of Fe3O4@PDA-MnO2:

[0056] Using TMB as the catalytic reaction substrate to evaluate its peroxidase-like activity, add 100 μL of 5 mmol / L TMB, 100 μL of 50 mmol / L H2O2, and 10 μL of 1 mg / mL Fe3O4@PDA-MnO2 into a 5 mL stoppered colorimetric tube, then add 2.79 mL of NaAc-HAc buffer solution (pH 4.0), mix well, make up the volume to 3 mL, measure the absorbance after reacting for 10 min, and at the same time, under the same conditions, compare the enzyme activity performance of the test without light irradiation, natural light irradiation, and 1.0 W / cm 2 and 808 nm infrared light irradiation for 10 min, measure the absorbance at a wavelength of 654 nm, and the results are as Figure 6 . Compared with the irradiation without 808 nm near-infrared light, the peroxidase-like activity of Fe3O4@PDA-MnO2 was significantly enhanced under near-infrared light irradiation, and Fe3O4@PDA-MnO2 exhibited the characteristic of enhanced peroxidase-like activity under near-infrared light.

[0057] The Michaelis catalytic kinetic parameters were also determined. Under natural light irradiation: fixing H2O2 and changing the concentration of TMB; fixing TMB and changing the concentration of H2O2; under 1.0 W / cm 2 and 808 nm infrared light irradiation: fixing H2O2 and changing the concentration of TMB; fixing TMB and changing the concentration of H2O2. The results are as Figures 7 to 10 shown in Table 1. The Michaelis constants of Fe3O4@PDA-MnO2 for the substrates TMB and H2O2 are K m 0.98 mmol / L and 1.48 mmol / L respectively, and the reaction rate constants are 0.45×10 -6 mol / L min and 0.12×10 -6 mol / L min. After infrared light irradiation, they are K m 0.20 mmol / L and 1.47 mmol / L respectively, and the reaction rate constants are 5.79×10 -6 mol / L min and 4.05×10 -6 mol / L min, indicating that infrared light irradiation increases the affinity between Fe3O4@PDA-MnO2 nanozyme and the substrate and the reaction rate.

[0058] Table 1 Michaelis catalytic kinetic parameters

[0059]

[0060] Cytotoxicity test:

[0061] The cytotoxicity of the nanozyme was detected using a CCK-8 cell viability kit. In the specific experiment, human umbilical vein endothelial cells and hepatoma cells (HUVECs and Hep G2, Beijing Nacrogen Biotech Co., Ltd.) were inoculated in 96-well plates and cultured for 24 h. Then, they were incubated with different concentrations of Fe3O4@PDA-MnO2 for 24 h and 48 h respectively. The cells were rinsed with PBS in fractions, and CCK-8 solution was added to each well to a concentration of 10%. Incubate at 37℃ and measure the absorbance at 450 nm; CCK-8 analysis ( Figure 11 ) showed that Fe3O4@PDA-MnO2 has no toxicity to cells.

[0062] Antibacterial test of Fe3O4@PDA-MnO2:

[0063] The bacterial strains used in the test were obtained from Beijing Nacrogen Biotech Co., Ltd.

[0064] Experimental method: Using Staphylococcus aureus ( S. aureus, ATCC 43300), methicillin-resistant Staphylococcus aureus (MRSA, ATCC-6538), Escherichia coli ( E. coli , ATCC-8099), ampicillin-resistant Escherichia coli ( E. coli , SHBCC D25148) were used as representative Gram-positive, Gram-negative strains and Gram-variable bacteria ( G. vaginalis ). The plate counting method was used to determine the antibacterial properties of Fe3O4@PDA-MnO2 by counting the number of CFUs. First, the above-mentioned strains were incubated in solid Luria-Bertani (LB) medium and solid nutrient broth medium for 24 h. A small amount of the formed colonies was picked with an inoculation loop and inoculated into a liquid medium (5 mL). Then, after incubation with shaking at 37 °C and 180 rpm for 12 h, a bacterial suspension (1×10 8 CFU / mL) was obtained and diluted to 1×10 5 CFU / mL with sterile phosphate buffer solution (PBS).

[0065] The materials were divided into four groups: blank control group, Fe3O4@PDA-MnO2, Fe3O4@PDA-MnO2+H2O2, Fe3O4@PDA-MnO2+H2O2+NIR group, where the concentration of Fe3O4@PDA-MnO2 was 20 μg / mL and the concentration of H2O2 was 50 mmol / L. The cultured bacteria were added to the phosphate buffer solution as the blank control group. After being irradiated with 1.0 W / cm 2 at 808 nm for 10 min or without infrared light irradiation treatment, they were incubated at 37 °C for 60 min. The bacterial suspension was diluted (100 μL) and evenly spread on LB solid medium and nutrient broth solid medium, and then cultured at 37 °C for 24 h. The number of colonies was counted to judge the antibacterial properties; and SEM characterization was carried out (attached Figure 12 , I was the blank control group, II was the Fe3O4@PDA-MnO2 group, III was the Fe3O4@PDA-MnO2+H2O2 group, and IV was the Fe3O4@PDA-MnO2+H2O2+NIR group). The results showed that: the blank control group had almost no antibacterial properties. Under 20 min of NIR irradiation, it showed excellent antibacterial effects against all bacteria, with a bactericidal rate of nearly 100% against all bacteria. The control group retained a complete cell morphology. However, in the presence of NIR or H2O2, the cell membranes of AREC, MRSA, and Gardnerella vaginalis showed wrinkles and shrinkage, while after treatment with Fe3O4@PDA-MnO2+H2O2+NIR, the cells were completely destroyed.

[0066] To further evaluate the antibacterial performance of Fe3O4@PDA-MnO2, we explored its anti-biofilm ability through crystal violet (CV) staining and quantified the biofilm by measuring the absorbance at 590 nm. The formation of biofilm could be clearly observed in the control group, and Fe3O4@PDA-MnO2+H2O2+NIR significantly inhibited the formation of bacterial biofilm after 48 h of incubation ( Figure 13 ), showing the lowest biofilm survival rate of 27.9 %.

[0067] To further determine the antibacterial ability of Fe3O4@PDA-MnO2, SEM observations were performed on AREC, MRSA, E. coli and S. aureus that were incubated with Fe3O4@PDA-MnO2+H2O2+NIR and those without such incubation ( Figure 14 , I was the blank control group, and II was the Fe3O4@PDA-MnO2+H2O2+NIR treatment group). The results showed that the control group retained a complete cell morphology. However, in the treatment group, the cell membranes of AREC, MRSA, E. coli and S. aureus showed wrinkles, shrinkage, complete rupture and even loss of the original morphology.

[0068] Example 2

[0069] Preparation method of hydrogel of Fe3O4@PDA-MnO2 nanomaterial

[0070] Stir 1.0 g of chitosan and dissolve it in 15 mL of acetic acid aqueous solution with a mass concentration of 1%, add 20 mg of Fe3O4@PDA-MnO2, and stir for 15 min to obtain solution A; add 0.6 - 0.8 g of sodium alginate to 14 mL of glycerol and stir for 1.5 h to obtain solution B; mix solution A and solution B, add 280 μL of 20 mg / mL calcium chloride solution under stirring, and continue to stir for 10 min to obtain Fe3O4@PDA-MnO2 hydrogel.

[0071] Construction of mouse BV model and anti-inflammatory effect test:

[0072] Mouse BV model: All animal experiments conformed to the "Guidelines for Animal Care". Female ICR mice at 10 weeks of age and weighing 18 - 20 g were selected as experimental animals and randomly divided into 4 groups with 8 mice in each group. For the vaginitis model, the mice were subcutaneously injected with 0.5 mg of 17β-estradiol. Three days after the injection, 20 μL of vaginal G. vaginalis (about 5.0×10 8CFU / mL) bacterial suspension, once a day for 3 consecutive days to infect the mice. After infection, different treatment methods were used: I was the healthy group; II was the infection group (blank control group without any treatment); III was the Fe3O4@PDA-MnO2 hydrogel treatment group (50 μL); IV was the Fe3O4@PDA-MnO2 hydrogel (50 μL) + H2O2 (10 μL) treatment group; V was the Fe3O4@PDA-MnO2 hydrogel (50 μL) + H2O2 (10 μL) + NIR treatment group (1.0 W / cm 2 , 808 nm infrared light irradiation); VI was the metronidazole treatment group (10 μL).

[0073] Evaluation of the swelling changes of murine vaginitis: After 10 days of treatment, the vagina of the blank group was significantly swollen (see Figure 15 , in which the right figure is the plate count chart corresponding to the vaginal secretion after being washed with PBS and plated), the swelling in the Fe3O4@PDA-MnO2 hydrogel + H2O2 group decreased, the swelling in the metronidazole group decreased, while there was no edema in the Fe3O4@PDA-MnO2 hydrogel + H2O2 + NIR group, and the vagina also shrank to normal.

[0074] The appearance changes of the reproductive system are as Figure 16 , and the vagina, cervix, "Y"-shaped uterus and ovaries of BV mice all showed varying degrees of inflammation manifestations such as congestion and redness. Longitudinally dissecting the vagina, purulent, bloody or purulent secretions were found in the vagina. After 10 days of treatment, the degree of redness and swelling of the reproductive system structure appearance in the Fe3O4@PDA-MnO2 hydrogel + H2O2 + NIR group of mice was significantly reduced compared with other groups.

[0075] ELISA detection of IL-6 and TNF-α levels:

[0076] After the last administration, the mice were fasted but not watered for 12 h, and then peripheral blood of the vaginal tissues of the mice was collected respectively. The levels of IL-6 and TNF-α in the plasma of mice in each group were detected by ELISA. The results showed that ( Figure 17 , the grouping situation of I-VI is the same as Figure 15 ), after 5 days of treatment, the levels of inflammatory cytokines IL-6 and TNF-α in the vaginal tissues of the Fe3O4@PDA-MnO2 hydrogel + H2O2 + NIR were significantly lower than those of other groups and the blank group (P < 0.05).

[0077] At the same time, on the 10th day, the infected BV tissues (heart, liver, spleen, lung, kidney, vagina, uterus) were harvested. First, H&E staining was performed to evaluate the pathological changes of the tissues, such as Figure 18As shown (Group I is the healthy group, Group II is the blank group, and Group III is the Fe3O4@PDA-MnO2 hydrogel + H2O2 + NIRI group), the results show that: no obvious tissue damage or lesions were observed in the mice treated with Fe3O4@PDA-MnO2 hydrogel + H2O2 + NIR in the 7 main tissues, which is consistent with the healthy group, indicating that this treatment method has good biosafety.

[0078] The above results indicate that the nanozyme Fe3O4@PDA-MnO2 prepared in the present invention has peroxidase-like activity and infrared photothermal performance, and can jointly antibacterial by simulating the peroxidase activity and photothermal performance of the nanozyme, and has an effective anti-inflammatory effect on murine bacterial vaginitis.

[0079] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in terms of form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A preparation method of Fe3O4@PDA-MnO2 nanomaterial, characterized in that, It includes the following steps: (1) Mix ethylene glycol and deionized water, and then add ammonia water and mix well; (2) Add dopamine solution to the mixed solution in step (1) and stir evenly; (3) Slowly drop the iron nitrate solution into step (2), and react at 50 - 70 °C for 12 - 15 h; (4) After cooling, centrifuge, and wash alternately with ethanol and water for 3 - 4 times, and obtain Fe3O4@PDA nanomaterials after vacuum drying; (5) Take the Fe3O4@PDA prepared in step (4) and KMnO4, ultrasonically disperse them in deionized water, then stir at room temperature for 1 - 1.5 h, centrifuge, and wash with deionized water for 3 - 4 times, and obtain Fe3O4@PDA-MnO2 nanomaterials after vacuum drying.

2. The Fe3O4@PDA-MnO2 nanomaterials obtained by the preparation method according to claim 1.

3. The application of the Fe3O4@PDA-MnO2 nanomaterials according to claim 2 in the preparation of drugs for treating vaginitis.

4. A hydrogel containing the Fe3O4@PDA-MnO2 nanomaterials according to claim 2.

5. A method for preparing a hydrogel containing the Fe3O4@PDA-MnO2 nanomaterial as described in claim 2, characterized in that: It includes the following steps: (1) Stir and dissolve 0.5 - 1.0 g of chitosan in 10 - 15 mL of acetic acid aqueous solution with a mass concentration of 1%, add 10 - 20 mg of Fe3O4@PDA-MnO2, and stir for 10 - 20 min to obtain solution A; (2) Add 0.6 - 0.8 g of sodium alginate to 12 - 15 mL of glycerol and stir for 1 - 1.5 h to obtain solution B; (3) Mix solution A and solution B, add 200 - 300 μL of 20 mg / mL calcium chloride solution under stirring, and continue to stir for 10 - 20 min to obtain the Fe3O4@PDA-MnO2 hydrogel.

6. The application of the hydrogel according to claim 4 in the preparation of drugs for treating vaginitis.

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