A self-assembled natural high-efficiency photothermal antibacterial nanoparticle and its preparation method and application

Abstract

The present invention belongs to the technical field of food sterilization, and discloses a self-assembled natural high-efficiency photothermal antibacterial nanoparticle and its preparation method and application. The preparation process of the self-assembled natural high-efficiency photothermal antibacterial nanoparticle includes: mixing a methanol solution of berberine with a methanol solution of rhein to obtain a mixed solution, and then mixing it with water to perform a self-assembly reaction to obtain a self-assembled nanoparticle solution; mixing the self-assembled nanoparticle solution with a methanol solution of chromium chloride to perform a coordination reaction to obtain self-assembled natural high-efficiency photothermal antibacterial nanoparticles. The self-assembled natural high-efficiency photothermal antibacterial nanoparticles prepared by the present invention can rapidly increase the temperature under the irradiation of near-infrared long-wave light, and play an instantaneous broad-spectrum bactericidal effect. Since berberine and rhein themselves have antibacterial effects, the prepared nanoparticles have a "double" synergistic bactericidal effect under the irradiation of near-infrared long-wave light.

Description

Technical Field

[0001] The present invention relates to the technical field of food sterilization, and in particular to a self-assembled natural high-efficiency photothermal antibacterial nanoparticle and a preparation method and application thereof. Background Art

[0002] Various industrial materials, medical biomaterials, sanitary products, agricultural products or foods are easily exposed to and harbor a large number of bacteria during processing, which seriously threatens human health. Antibiotics are still considered the main strategy for treating bacterial infections. However, the long-term and excessive use of antibiotics will lead to the accelerated evolution and emergence of bacteria with antibiotic resistance. At the same time, the types of new antibiotics on the market are gradually decreasing. Therefore, relying solely on antibiotics to control bacterial infections will further increase the risk of causing bacterial resistance.

[0003] At present, the development of natural antimicrobial agents has received more and more attention. However, natural antimicrobial agents generally have the problem of low antimicrobial activity in practical applications. Photodynamic sterilization can use the local heat generated by light irradiation to inactivate microorganisms. It is an effective physical sterilization method that does not lead to the development of microbial resistance. Therefore, using photodynamic sterilization technology to further improve the bactericidal activity of natural antimicrobial agents is a solution with great development potential. Some metal (such as Au, Ag, Cu, etc.) nanoparticles have become commonly used photothermal sterilization materials because of their good photothermal conversion efficiency. Unfortunately, these metal nanoparticles usually have certain cytotoxicity and are not easy to degrade. Long-term use may pose a threat to human health and the environment, seriously restricting their further promotion and application.

[0004] Therefore, developing a natural, efficient, and biocompatible photothermal sterilizer has very important practical application value. Summary of the invention

[0005] The purpose of the present invention is to provide a self-assembled natural high-efficiency photothermal antibacterial nanoparticle and a preparation method and application thereof, so as to solve the problems existing in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, comprising the following steps:

[0008] (1) mixing a methanol solution of berberine and a methanol solution of rhein to obtain a mixed solution, and then mixing the mixed solution with water to perform a self-assembly reaction to obtain a self-assembled nanoparticle solution;

[0009] (2) The self-assembled nanoparticle solution is mixed with a methanol solution of chromium chloride to carry out a coordination reaction, thereby obtaining self-assembled natural and highly efficient photothermal antibacterial nanoparticles.

[0010] Preferably, in the above-mentioned method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, the concentration of the methanol solution of berberine in step (1) is 3-5wt%, and the concentration of the methanol solution of rhein in step (1) is 2-4wt%.

[0011] Preferably, in the above-mentioned method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, the volume ratio of the methanol solution of berberine to the methanol solution of rhein in step (1) is 1-3:1-3, and the volume ratio of the mixed solution and water in step (1) to the methanol solution of chromium chloride in step (2) is 8-10:80-100:10-12.

[0012] Preferably, in the above-mentioned method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, the time of the self-assembly reaction in step (1) is 5 to 6 hours, the temperature of the self-assembly reaction is 60 to 70° C., and the stirring speed is 300 to 600 r / min.

[0013] Preferably, in the above-mentioned method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, the molar volume ratio of chromium chloride in the methanol solution of chromium chloride to the methanol solution of chromium chloride in step (2) is 0.5-1 mmol:5-15 mL.

[0014] Preferably, in the above-mentioned method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, the coordination reaction in step (2) is carried out under light-proof conditions, the temperature of the coordination reaction is 20-25° C., and the time of the coordination reaction is 4-6 hours.

[0015] Preferably, in the above-mentioned method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, after the coordination reaction in step (2) is completed, the method further comprises: dialysis, the dialysis temperature is 2 to 10° C., and the dialysis time is 24 to 36 hours.

[0016] The present invention also provides self-assembled natural high-efficiency photothermal antibacterial nanoparticles prepared by the preparation method of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles.

[0017] The present invention also provides an application of self-assembled natural high-efficiency photothermal antibacterial nanoparticles in the preparation of antibacterial agents.

[0018] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) Berberine and rhein are prepared into nanoparticles by self-assembly and then reacted with chromium chloride for coordination and encapsulation to obtain natural nanoparticles with a particle size of 50 to 140 nm. The nanoparticles significantly improve the physicochemical stability and bioavailability of berberine and rhein in practical applications.

[0020] (2) The nanoparticles prepared by the present invention can rapidly increase the temperature under the irradiation of near-infrared long-wave light (NILWL), achieving an instantaneous broad-spectrum bactericidal effect. Since berberine and rhein have antibacterial effects themselves, the prepared nanoparticles can achieve a "double" synergistic bactericidal effect under the irradiation of NILWL, and have a highly effective bactericidal activity against drug-resistant strains.

[0021] (3) The self-assembled natural high-efficiency photothermal antibacterial nanoparticles prepared by the present invention have the characteristics of good biocompatibility, green safety and non-toxicity.

[0022] (4) The preparation method of the present invention is simple, easy to operate, and does not produce any toxic or harmful by-products, and is suitable for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments or the prior art are briefly introduced below.

[0024] Figure 1 The particle size distribution diagram and transmission electron microscopy diagram of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Example 1; wherein a is the particle size distribution diagram, and b is the transmission electron microscopy diagram;

[0025] Figure 2 The photothermal performance diagram of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in the comparative example;

[0026] Figure 3 The graph is a graph showing the bactericidal performance of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in the comparative example against methicillin-resistant Staphylococcus aureus;

[0027] Figure 4 The graphs are the bactericidal performance of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in the comparative example against Escherichia coli;

[0028] Figure 5 The graph is a graph showing the bactericidal performance of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in the comparative example against methicillin-resistant Staphylococcus aureus in a food model;

[0029] Figure 6This is a graph showing the bactericidal performance of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in the comparative example against Escherichia coli in a food model. DETAILED DESCRIPTION

[0030] The present invention provides a method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, comprising the following steps:

[0031] (1) mixing a methanol solution of berberine and a methanol solution of rhein to obtain a mixed solution, and then mixing the mixed solution with water to perform a self-assembly reaction to obtain a self-assembled nanoparticle solution;

[0032] (2) The self-assembled nanoparticle solution is mixed with a methanol solution of chromium chloride to carry out a coordination reaction, thereby obtaining self-assembled natural and highly efficient photothermal antibacterial nanoparticles.

[0033] In the present invention, the temperature for mixing the methanol solution of berberine and the methanol solution of rhein in step (1) is preferably 25-30°C, more preferably 25, 26, 27, 28, 29 or 30°C, more preferably 28°C; the specific method of mixing is stirring, the stirring time is preferably 30-60min, more preferably 30, 35, 40, 45, 50, 55 or 60min, more preferably 50min, and the stirring speed is preferably 1000r / min.

[0034] In the present invention, the concentration of the methanol solution of berberine in the step (1) is preferably 3-5wt%, more preferably 3, 3.2, 3.5, 4, 4.5, 4.7 or 5wt%, and more preferably 4wt%; the concentration of the methanol solution of rhein in the step (1) is preferably 2-4wt%, more preferably 2, 2.3, 2.5, 2.8, 3, 3.5, 3.8 or 4wt%, and more preferably 3 or 3.5wt%.

[0035] In the present invention, the volume ratio of the methanol solution of berberine to the methanol solution of rhein in the step (1) is preferably 1-3:1-3, more preferably 1.2-2.7:1.2-2.7, and more preferably 1.5:2; the volume ratio of the mixed solution in the step (1), water, and the methanol solution of chromium chloride in the step (2) is preferably 8-10:80-100:10-12, more preferably 8.2-9.7:82-97:10.5-11.8, and more preferably 8.5:85:11.

[0036] In the present invention, the time of the self-assembly reaction in step (1) is preferably 5 to 6 hours, more preferably 5, 5.25, 5.5, 5.75 or 6 hours, and more preferably 5.5 hours; the temperature of the self-assembly reaction is preferably 60 to 70°C, more preferably 60, 62, 65, 68 or 70°C, and more preferably 60°C; the stirring speed is preferably 400 to 600 r / min, more preferably 400, 450, 500, 550 or 600 r / min, and more preferably 450 r / min.

[0037] In the present invention, the molar volume ratio of chromium chloride to chromium chloride in the methanol solution of chromium chloride in step (2) is 0.5-1 mmol:5-15 mL, more preferably 0.65-0.85 mmol:7-13 mL, and more preferably 0.7 mmol:9 mL.

[0038] In the present invention, the specific method of mixing in step (2) is stirring, and the stirring time is preferably 5 to 10 minutes, more preferably 5, 6, 7, 8, 9 or 10 minutes, more preferably 7 or 8 minutes, and the stirring speed is preferably 400 to 600 r / min, more preferably 400, 450, 500, 550 or 600 r / min, more preferably 450 r / min.

[0039] In the present invention, the coordination reaction in step (2) is carried out with stirring under light-proof conditions, and the temperature of the coordination reaction is preferably 20-25°C, more preferably 20, 21, 22, 23, 24 or 25°C, more preferably 20°C; the time of the coordination reaction is preferably 4-6h, more preferably 4, 4.25, 4.75, 5, 5.5, 5.75 or 6h, more preferably 5h; the stirring speed is preferably 400r / min.

[0040] In the present invention, after the coordination reaction in step (2) is completed, the method further comprises: dialysis, wherein the dialysis temperature is preferably 2-10°C, more preferably 2, 4, 5, 6, 8 or 10°C, more preferably 4 or 5°C; the dialysis time is preferably 24-36h, more preferably 24, 25, 28, 30, 32, 35 or 36h, more preferably 30h.

[0041] The present invention also provides self-assembled natural high-efficiency photothermal antibacterial nanoparticles prepared by the preparation method of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles.

[0042] The present invention also provides an application of self-assembled natural high-efficiency photothermal antibacterial nanoparticles in the preparation of antibacterial agents.

[0043] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Example 1

[0045] (1) preparing a 3 wt % berberine methanol solution with a pH value of 7 and a 2 wt % rhein methanol solution with a pH value of 7 respectively;

[0046] A 3 wt % berberine methanol solution and a 2 wt % rhein methanol solution were mixed at a volume ratio of 1:1 at 25°C at a speed of 1000 r / min for 30 min to obtain a mixed solution, and then 8 mL of the mixed solution was mixed with 80 mL of 60°C distilled water, the temperature was kept constant at 60°C, and then stirred at a speed of 450 r / min for a self-assembly reaction for 5 h to obtain a self-assembled nanoparticle solution;

[0047] (2) The self-assembled nanoparticle solution was mixed with 10 mL of chromium chloride methanol solution (chromium chloride content was 0.5 mmol) at 450 r / min for 5 min, and then the coordination reaction was carried out at 400 r / min for 4 h at room temperature in the dark. After the coordination reaction was completed, it was dialyzed with deionized water at 4°C for 24 h to obtain self-assembled natural and highly efficient photothermal antibacterial nanoparticles.

[0048] The particle size distribution and transmission electron microscopy (TEM) images of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles prepared above are as follows: Figure 1 As shown. Figure 1 It can be seen that most of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles are approximately uniform spherical particles with a size of 50 to 140 nm.

[0049] Example 2

[0050] (1) preparing a 4 wt % berberine methanol solution with a pH value of 7 and a 3 wt % rhein methanol solution with a pH value of 7 respectively;

[0051] A 4 wt % berberine methanol solution and a 3 wt % rhein methanol solution were stirred at a volume ratio of 2:1 at 28°C at a speed of 1000 r / min for 45 min to obtain a mixed solution, and then 9 mL of the mixed solution was mixed with 90 mL of 65°C distilled water, the temperature was kept constant at 65°C, and then stirred at a speed of 450 r / min for a self-assembly reaction for 5.5 h to obtain a self-assembled nanoparticle solution;

[0052] (2) The self-assembled nanoparticle solution was mixed with 10 mL of chromium chloride methanol solution (chromium chloride content was 0.8 mmol) at 450 r / min for 5 min, and then the coordination reaction was carried out at 400 r / min for 5 h at room temperature in the dark. After the coordination reaction was completed, it was dialyzed with deionized water at 4°C for 30 h to obtain self-assembled natural and highly efficient photothermal antibacterial nanoparticles.

[0053] Example 3

[0054] (1) preparing a 5 wt % methanol solution of berberine at a pH of 7 and a 4 wt % methanol solution of rhein at a pH of 7 respectively;

[0055] A 5 wt % berberine methanol solution and a 4 wt % rhein methanol solution were stirred at a volume ratio of 1.5:2 at 30°C and a speed of 1000 r / min for 60 min to obtain a mixed solution, and then 10 mL of the mixed solution was mixed with 100 mL of 70°C distilled water, the temperature was kept constant at 70°C, and then stirred at a speed of 450 r / min for a self-assembly reaction for 6 h to obtain a self-assembled nanoparticle solution;

[0056] (2) The self-assembled nanoparticle solution was mixed with 10 mL of chromium chloride methanol solution (chromium chloride content was 1.0 mmol) at 450 r / min for 5 min, and then the coordination reaction was carried out at 400 r / min for 6 h in the dark at room temperature. After the coordination reaction was completed, it was dialyzed with deionized water at 4°C for 36 h to obtain self-assembled natural and highly efficient photothermal antibacterial nanoparticles.

[0057] Comparative Example 1

[0058] A 4 wt % berberine methanol solution with a pH value of 7 and a 3 wt % rhein methanol solution with a pH value of 7 were prepared respectively; the 4 wt % berberine methanol solution and the 3 wt % rhein methanol solution were stirred and mixed at a volume ratio of 2:1 at 28°C at a speed of 1000 r / min for 45 min to obtain a mixed solution, and then 9 mL of the mixed solution was mixed with 90 mL of 65°C distilled water, the temperature was kept constant at 65°C, and then the self-assembly reaction was carried out by stirring at a speed of 450 r / min for 5.5 hours to obtain a self-assembled natural antibacterial nanoparticle solution.

[0059] Photothermal determination:

[0060] The self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in Comparative Example 1 were respectively prepared into a nanoparticle solution with a concentration of 5 mg / mL with distilled water, and 300 μL of the solution was added to a 3 mL centrifuge tube and illuminated with near-infrared long-wave light (NILWL) (wavelength: 1500 nm, power: 2 W / cm 2) After irradiation for 0min, 3min, 6min, 9min, 12min, 15min and 18min, the temperature change was measured with an SH-X temperature tester. The results are as follows Figure 2 shown.

[0061] Depend on Figure 2 It can be seen that after the nanoparticles in Comparative Example 1 without adding chromium chloride were irradiated with near-infrared long-wave light (NILWL), the temperature of the nanoparticles did not increase significantly. However, the temperature of the nanoparticles in Examples 1 to 3 increased significantly, which shows that the self-assembled nanoparticles of berberine and rhein alone cannot generate heat energy under NILWL irradiation. The photothermal properties of the nanoparticles in Examples 1 to 3 are given by the chromium ions wrapped on the outer surface of the particles. Among them, the temperature of the nanoparticles in Example 3 rose fastest after NILWL irradiation, indicating that its photothermal performance is proportional to the amount of chromium chloride added within a certain range.

[0062] Bactericidal performance determination:

[0063] (1) Determination of bactericidal properties against methicillin-resistant Staphylococcus aureus (MRSA):

[0064] Illumination group: Take the methicillin-resistant Staphylococcus aureus cultured to the logarithmic phase and prepare it with sterile distilled water to a concentration of 10 5 CFU / mL of bacterial suspension, the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Example 1 were prepared into a nanoparticle solution with a concentration of 5 mg / mL with distilled water, and then 100 μL of the bacterial suspension was mixed with 100 μL of the nanoparticle solution to obtain a sample, which was irradiated under NILWL for 9 min; then the bactericidal activity of the sample was determined by the plate colony counting method, and the specific method was as follows: 100 μL of the sample was spread on a nutrient agar plate, and the colony count was performed after culturing at 37°C for 24 h, and the number of colonies was repeated three times to take the average value;

[0065] No light control group: the same as the light group, the only difference is: the samples were placed in a dark environment for 9 minutes;

[0066] Blank light control group: the same as the light control group, the only difference is that sterile distilled water is used instead of the self-assembled natural high-efficiency photothermal antibacterial nanoparticle solution;

[0067] Blank light-free control group: The same as the light-free control group, the only difference is that sterile distilled water is used instead of the self-assembled natural high-efficiency photothermal antibacterial nanoparticle solution;

[0068] (2) Determination of bactericidal properties against Escherichia coli (E.coli):

[0069] The method for determining the bactericidal performance of the self-assembled natural antibacterial nanoparticle solution against methicillin-resistant Staphylococcus aureus (MRSA) is consistent with the above method, with the only difference being that the MRSA is replaced by Escherichia coli.

[0070] The self-assembled natural high-efficiency photothermal antibacterial nanoparticles of Examples 2 to 3 and the self-assembled natural antibacterial nanoparticles of Comparative Example 1 were tested for their bactericidal properties against methicillin-resistant Staphylococcus aureus and Escherichia coli using the same method.

[0071] The bactericidal effects of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in Comparative Example 1 on MRSA are as follows Figure 3 As shown, the bactericidal effects of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in Comparative Example 1 on E. coli are as follows Figure 4 shown.

[0072] Depend on Figure 3 and Figure 4 It can be seen that there is no significant difference in the number of colonies in the light-free group of comparative example 1 and the light-exposed group of comparative example 1, while the number of colonies in the light-free group of comparative example 1 and the light-exposed group of comparative example 1 is significantly lower than that in the light-free group of the blank control group and the light-exposed group of the blank control group, which is mainly due to the antibacterial activity of berberine and rhein in comparative example 1. It is worth mentioning that Figure 3 and Figure 4 It can be clearly seen that the total number of colonies in the light groups of all embodiments decreased significantly compared with the light-free groups of the embodiments, and MRSA and E. coli were not detected in the light groups of Examples 1 to 3. This fully demonstrates that the self-assembled natural high-efficiency photothermal antibacterial nanoparticles prepared in Examples 1 to 3 exhibited high-efficiency bactericidal activity against bacteria including drug-resistant bacteria. At the same time, this shows that NILWL irradiation treatment can significantly enhance the antibacterial activity of nanoparticles. The photothermal effect of self-assembled antibacterial nanoparticles and the antibacterial activity of berberine and rhein themselves achieve synergistic and efficient bactericidal effects.

[0073] Application assays in food models:

[0074] Illumination group: The self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Example 1 were prepared into a nanoparticle solution with a concentration of 5 mg / mL using distilled water. 10 μL of the prepared MRSA bacterial suspension (concentration of 10 5CFU / mL) was mixed with an equal volume of nanoparticle solution to obtain a sample, which was irradiated with NILWL for 9 minutes and then applied to the surface of fresh pork with a size of 3 cm×2 cm×2 cm. The pork was placed at 37°C for 6 hours and the bacterial survival rate was determined by the plate colony counting method, where the bacterial survival rate (%) was the ratio of the colony number of the experimental sample to the colony number of the blank control sample multiplied by 100%. Each sample was performed in triplicate and the average value was taken.

[0075] No light control group: the same as the light group, the only difference is: the samples were placed in a dark environment for 9 minutes;

[0076] Blank control group: the same as the light-irradiated group, the only difference is that sterile distilled water was used instead of the self-assembled natural high-efficiency photothermal antibacterial nanoparticle solution;

[0077] The same method was used to determine the bactericidal effect of each group of samples on E. coli in the food model. At the same time, the self-assembled natural high-efficiency photothermal antibacterial nanoparticles of Examples 2 to 3 and the self-assembled natural antibacterial nanoparticles of Comparative Example 1 were tested in the same way.

[0078] The bactericidal effects of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in Comparative Example 1 on MRSA in the food model are as follows: Figure 5 As shown, the bactericidal effects of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles in Examples 1 to 3 and the self-assembled natural antibacterial nanoparticles in Comparative Example 1 on E. coli in the food model are as follows: Figure 6 shown.

[0079] Depend on Figure 5 and Figure 6 It can be seen that the survival rates of MRSA and E.coli in pork after the nanoparticles in the lightless and lightless groups of Comparative Example 1 and Examples 1 to 3 were all above 55%, which shows that the nanoparticles in the lightless and lightless groups of Comparative Example 1 and Examples 1 to 3 have certain bactericidal activity, but the bactericidal effect is not ideal. As mentioned above, the reason for showing a certain bactericidal activity is due to the bactericidal activity of berberine and rhein itself. However, it can be clearly seen from the figure that the survival rates of MRSA and E.coli in the NILWL irradiation treatment groups of Examples 1 to 3 have decreased significantly, and the survival rates of MRSA have dropped to 2.8%, 1.5% and 0%, respectively, and the survival rates of E.coli have dropped to 1.3%, 0% and 0%, respectively. This shows that the self-assembled natural and efficient photothermal antibacterial nanoparticles prepared by the present invention still have efficient bactericidal activity even in the actual application of food models. It can be seen that it has great practical application value as a natural green and efficient bactericide.

[0080] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing self-assembled natural high-efficiency photothermal antibacterial nanoparticles, characterized in that: The following steps are involved: (1) mixing a methanol solution of berberine and a methanol solution of rhein to obtain a mixed solution, and then mixing the mixed solution with water to perform a self-assembly reaction to obtain a self-assembled nanoparticle solution; (2) mixing the self-assembled nanoparticle solution with a methanol solution of chromium chloride to carry out a coordination reaction to obtain self-assembled natural high-efficiency photothermal antibacterial nanoparticles; The volume ratio of the methanol solution of berberine to the methanol solution of rhein in step (1) is 1-3:1-3, and the volume ratio of the mixed solution in step (1), water and the methanol solution of chromium chloride in step (2) is 8-10:80-100:10-12; The self-assembly reaction time in step (1) is 5 to 6 hours, the self-assembly reaction temperature is 60 to 70° C., and the stirring speed is 300 to 600 r / min; In the step (2), the molar volume ratio of chromium chloride in the methanol solution of chromium chloride to the methanol solution of chromium chloride is 0.5-1 mmol: 5-15 mL; The coordination reaction in step (2) is carried out in a light-proof condition, the coordination reaction temperature is 20 to 25° C., and the coordination reaction time is 4 to 6 hours.

2. The method for preparing the self-assembled natural high-efficiency photothermal antibacterial nanoparticles according to claim 1, characterized in that: The concentration of the methanol solution of berberine in step (1) is 3-5 wt %, and the concentration of the methanol solution of rhein in step (1) is 2-4 wt %.

3. The method for preparing the self-assembled natural high-efficiency photothermal antibacterial nanoparticles according to claim 2, characterized in that: After the coordination reaction in step (2) is completed, the method further comprises: dialysis, wherein the dialysis temperature is 2 to 10° C., and the dialysis time is 24 to 36 hours.

4. The self-assembled natural high-efficiency photothermal antibacterial nanoparticles prepared by the preparation method of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles according to any one of claims 1 to 3.

5. Use of the self-assembled natural high-efficiency photothermal antibacterial nanoparticles according to claim 4 in the preparation of antibacterial agents.

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