Bismuth-based heterogeneous material for promoting healing of diabetic wound as well as preparation method and application of bismuth-based heterogeneous material

Abstract

The invention provides a bismuth-based heterogeneous material for promoting healing of diabetic wounds and a preparation method and application thereof. The bismuth-based heterogeneous material comprises a bismuth-based porphyrin metal organic framework, and the surface of the bismuth-based porphyrin metal organic framework is modified with Au-Pt nanoparticles. According to the bismuth-based heterogeneous material disclosed by the invention, microenvironments of bacterial infection, high glucose, active oxygen damage, inflammatory disorder, pH rise and oxygen deficit of diabetic wounds are improved through multiple antibacterial effects and enzyme catalysis effects, so that the healing of the diabetic wounds is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical materials, and particularly to a bismuth-based heterogeneous material for promoting the healing of diabetic wounds, its preparation method and application. Background Art

[0002] Diabetic wounds, such as diabetic foot, are common and serious complications of diabetes, which are characterized by high incidence, difficult treatment, high recurrence rate and high mortality. The hyperglycemic environment of the wounds in diabetic patients will induce adverse microenvironmental factors such as reactive oxygen species (ROS) damage, increased pH, inflammatory disorders, hypoxia, etc. These factors interact with each other and seriously damage the wound healing ability. Among them, the hyperglycemic and high-pH wound microenvironment provides favorable conditions for bacterial colonization. More than half of diabetic wounds will suffer from bacterial infection, which further exacerbates inflammatory damage and increases the risk of tissue necrosis, amputation and even death of patients. Therefore, improving the complex microenvironment of diabetic wounds, especially controlling infection, is the key to treating diabetic wounds.

[0003] As an alternative therapy to antibiotics, photodynamic therapy (PDT), photothermal therapy (PTT), chemodynamic therapy (CDT) and nanozyme therapy have been widely used in the treatment of wound infections. Compared with the continuous generation of ROS in CDT and nanozyme therapy, PDT and PTT are based on photo-responsive materials to convert light energy into ROS and heat energy in a short time to kill bacteria, which reduces the risk of long-term toxicity caused by the continuous release of ROS. Therefore, it is very important to develop photo-responsive materials with strong photo-responsive performance and high biosafety.

[0004] Different from the common antibacterial processes based on ROS and heat energy, extracellular electron transfer (EET) occurring at the interface between bacteria and semiconductors is an emerging antibacterial pathway. This antibacterial mechanism based on EET involves the forced capture of electrons by semiconductor materials during the aerobic respiration process of aerobic bacteria. When the redox potential of the semiconductor material is lower than the biological redox potential (BRP) of the membrane respiratory chain of Staphylococcus aureus and Escherichia coli, it will cause the electrons in the respiratory metabolic chain to be forced to transfer to the semiconductor material through the contact interface, resulting in the obstruction of aerobic respiration metabolism of bacteria and ultimately death.

[0005] In addition to controlling bacterial infection, curing diabetic wounds also requires correcting microenvironmental factors such as hyperglycemia, high pH, hypoxia, and ROS damage. Nanozymes with antioxidant functions such as superoxide dismutase (SOD) and catalase (CAT) can promote the healing of diabetic wounds by alleviating oxidative damage and regulating immune homeostasis. The glucose oxidase (Gox) and CAT enzyme activities of Au-Pt alloy nanozymes can improve the hyperglycemic, oxidative damage and hypoxic environment of diabetic wounds. In addition, gluconic acid produced during the catalytic process of Gox to generate H2O2 can acidify the wound environment.

[0006] Most nano-drugs and dressings target single or limited adverse factors in diabetic wounds and are difficult to meet the need for regulating the complex microenvironment of diabetic wounds. Summary of the Invention

[0007] The present invention provides a bismuth-based heteromaterial for promoting diabetic wound healing, its preparation method and application. Bi-TCPP@Au-Pt has rapid bactericidal ability based on PDT and PTT and the effect of continuously killing Staphylococcus aureus based on EET. Subsequently, the cascade catalytic effect played improves the microenvironmental factors of high glucose, high pH, high ROS and hypoxia. Finally, M1 macrophages at the diabetic wound site are transformed into M2 type, immune disorders are corrected, and tissue remodeling is accelerated.

[0008] The technical solution of the present invention is realized as follows: A bismuth-based heteromaterial for promoting diabetic wound healing, comprising a bismuth-based porphyrin metal-organic framework (Bi-TCPP), and the surface of the bismuth-based porphyrin metal-organic framework is modified with Au-Pt nanoparticles. In Bi-TCPP, Bi is the metal node and TCPP is the organic ligand; the Au-Pt nanoparticles are uniformly distributed on the surface of Bi-TCPP.

[0009] A preparation method of a bismuth-based heteromaterial for promoting diabetic wound healing, comprising the following steps:

[0010] (1) Synthesize a bismuth-based porphyrin metal-organic framework by a solvothermal method;

[0011] (2) Modify Au-Pt nanoparticles on the surface of the bismuth-based porphyrin metal-organic framework by a co-reduction method.

[0012] Further, in step (1), the specific method for synthesizing the bismuth-based porphyrin metal-organic framework is as follows:

[0013] Dissolve Bi(NO3)3·5H2O and meso-tetrakis(4-carboxyphenyl)porphine (TCPP) in a solvent, mix well and heat. The reaction product is washed and dried to obtain the bismuth-based porphyrin metal-organic framework.

[0014] Further, in step (2), the specific method for modifying Au-Pt nanoparticles is as follows: Disperse the bismuth-based porphyrin metal-organic framework in deionized water, then add HAuCl4 and H2PtCl6·6H2O, mix well, and add NaBH4 for a co-reduction reaction. The reaction product is washed and dried to obtain the bismuth-based heteromaterial (Bi-TCPP@Au-Pt).

[0015] Further, in step (1), the solvent includes N,N-dimethylformamide and deionized water, and the volume ratio of N,N-dimethylformamide to deionized water is (5-15):(0.5-4).

[0016] Further, in step (1), the molar ratio of Bi(NO3)3·5H2O to TCPP is (1.8 - 2.2):(0.9 - 1.1); the heating temperature is 100 - 160 °C, and the reaction time is 8 - 36 h; in step (1), the concentration of Bi(NO3)3·5H2O in the solvent is (1 - 50) mmol / L.

[0017] Further, in step (2), the bismuth-based porphyrin metal-organic framework is dispersed in deionized water. After ultrasonic dispersion, HAuCl4 and H2PtCl6·6H2O are added. After ultrasonic treatment, under the conditions of an ice-water bath and stirring, a NaBH4 solution freshly prepared with cold water is added at one time. The concentration of the NaBH4 solution is 1 - 3 mg / mL, and the temperature of the cold water is 4 - 8 °C. Stirring reaction continues, and the reaction product is washed and dried to obtain the bismuth-based heterogeneous material. Fresh preparation with cold water is to reduce the reaction of NaBH4 with water.

[0018] Further, in step (2), the dosage ratio of the bismuth-based porphyrin metal-organic framework to deionized water is (0.05 - 5) mg:(0.5 - 2) mL.

[0019] Further, in step (2), the mass ratio of the bismuth-based porphyrin metal-organic framework, HAuCl4, H2PtCl6·6H2O, and NaBH4 is (15 - 25):(0.5 - 4):(1 - 8):(0.25 - 2).

[0020] Use of a bismuth-based heterogeneous material in the preparation of a drug or dressing for promoting diabetic wound healing.

[0021] Advantages of the present invention:

[0022] The bismuth-based heterogeneous material Bi-TCPP@Au-Pt prepared by the present invention has a rapid bactericidal effect based on PDT and PTT and a continuous bactericidal effect based on EET. Under 660 nm visible light irradiation, 99.9% of Staphylococcus aureus and Escherichia coli can be killed in only 5 minutes. Under dark conditions, after co-culturing for 4 h, 99.9% of Staphylococcus aureus can be killed based on EET bactericidal.

[0023] The bismuth-based heterogeneous material Bi-TCPP@Au-Pt prepared by the present invention can continuously catalyze the decomposition of glucose and hydrogen peroxide, and produce gluconic acid and oxygen, alleviating the adverse microenvironmental factors of high sugar, high ROS, high pH, and hypoxia in diabetic wounds.

[0024] The Bi-based heteromaterial Bi-TCPP@Au-Pt prepared by the present invention is obtained by co-reducing and modifying Au-Pt nanoparticles on the surface of Bi-TCPP, and has a remarkable effect on promoting diabetic wound healing. The preparation process is simple and efficient, and is suitable for large-scale industrial production. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is the scanning electron microscope image of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1;

[0027] Figure 2 It is the transmission electron microscope image of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1;

[0028] Figure 3 It is the XRD pattern of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1;

[0029] Figure 4 It is the XPS spectrum of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1;

[0030] Figure 5 It is the test of the photodynamic and photothermal properties of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1;

[0031] Figure 6 It is the effect diagram of the photodynamic and photothermal antibacterial of Bi-TCPP@Au-Pt prepared in Example 1.

[0032] Figure 7 It is the effect diagram of the antibacterial based on extracellular electron transfer of Bi-TCPP@Au-Pt prepared in Example 1;

[0033] Figure 8 It is the detection result of the glucose oxidase activity of Bi-TCPP@Au-Pt prepared in Example 1;

[0034] Figure 9 It is the detection result of the catalase activity of Bi-TCPP@Au-Pt prepared in Example 1;

[0035] Figure 10The results of cell viability test of NIH / 3T3 and HUVEC cells after being treated with Bi-TCPP@Au-Pt prepared in Example 1;

[0036] Figure 11 This is the in vitro hemolytic result of Bi-TCPP@Au-Pt prepared in Example 1;

[0037] Figure 12 This is a diagram showing the in vivo antibacterial effect of Bi-TCPP@Au-Pt prepared in Example 1. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0039] Example 1

[0040] A method for preparing a bismuth-based heterogeneous material comprises the following steps:

[0041] (1) Synthesis of Bi-TCPP: Bi(NO3)3·5H2O (38.8058 mg, 0.08 mmol) and TCPP (31.6300 mg, 0.04 mmol) were dissolved in a mixed solvent consisting of DMF (13 mL) and deionized water (2 mL). After thorough mixing, the solution was placed in polytetrafluoroethylene for reaction and heated at 120°C for 12 h. The reaction product was centrifuged, washed with deionized water, and vacuum freeze-dried for 18 h to obtain Bi-TCPP.

[0042] (2) Synthesis of Bi-TCPP@Au-Pt: Disperse 20 mg Bi-TCPP in deionized water (10 mL). After ultrasonication for 15 min, add HAuCl4 (1.0440 mg) and H2PtCl6·6H2O (6.3600 mg). Ultrasonication is performed for 15 min. Under vigorous stirring in an ice-water bath, a NaBH4 solution prepared in cold water (the amount of NaBH4 is 1.6550 mg, the concentration of the NaBH4 solution is 2 mg / mL, and the temperature of the cold water is 4°C) is quickly added at one time. After stirring for 10 min, the product is centrifuged and washed with deionized water three times. The precipitate is freeze-dried in vacuum for 18 h.

[0043] Example 2

[0044] A method for preparing a bismuth-based heterogeneous material comprises the following steps:

[0045] (1) Synthesis of Bi-TCPP: Dissolve Bi(NO3)3·5H2O (38.8058 mg, 0.08 mmol) and TCPP (31.6300 mg, 0.04 mmol) in a mixed solvent composed of DMF (14 mL) and deionized water (1 mL). After thorough mixing, place the solution in a polytetrafluoroethylene reactor and heat it at 120 °C for 24 h. The reaction product is centrifuged, washed with deionized water, and vacuum freeze-dried for 18 h to obtain Bi-TCPP;

[0046] (2) Synthesis of Bi-TCPP@Au-Pt: Disperse 20 mg of Bi-TCPP in deionized water (20 mL). After sonication for 15 min, add HAuCl4 (1.7360 mg) and H2PtCl6·6H2O (5.2940 mg), and sonicate for another 15 min. Under vigorous stirring in an ice-water bath, quickly add a freshly prepared NaBH4 solution in cold water at one time (the amount of NaBH4 is 1.50 mg, the concentration of the NaBH4 solution is 2 mg / mL, and the temperature of the cold water is 4 °C). After continuous stirring for 10 min, the product is centrifuged, washed with deionized water three times, and the precipitate is vacuum freeze-dried for 24 h.

[0047] 1. Electron microscopy images of Bi-TCPP and Bi-TCPP@Au-Pt

[0048] The scanning electron microscopy images of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1 are as Figure 1 shown. It can be seen that Bi-TCPP is hexagonal prism-shaped, with a small amount of flocculent impurities around it. After modifying with Au-Pt nanoparticles, the surface of Bi-TCPP@Au-Pt becomes rough.

[0049] The transmission electron microscopy images of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1 are as Figure 2 shown. It can be seen that the Au-Pt nanoparticles are uniformly distributed on the surface of the Bi-TCPP particles.

[0050] 2. XRD patterns and XPS spectra of Bi-TCPP and Bi-TCPP@Au-Pt.

[0051] The XRD patterns of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1 are as Figure 3 shown. Diffraction peaks belonging to Au nanoparticles and Pt nanoparticles appear in the XRD pattern of the Bi-TCPP@Au-Pt particles in the range of 35 - 90 °, indicating that the Au-Pt nanoparticles have successfully grown on the surface of the Bi-TCPP particles.

[0052] The XPS spectra of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1 are as follows Figure 4 shown. Bi-TCPP mainly contains Bi, C, N, and O, while additional signal peaks belonging to Au and Pt appear in Bi-TCPP@Au-Pt, indicating that Au-Pt nanoparticles have successfully grown on the surface of Bi-TCPP particles.

[0053] 3. Photodynamic and photothermal performance tests of Bi-TCPP and Bi-TCPP@Au-Pt.

[0054] Diphenylbenzofuran (DPBF) was used to detect the generation of singlet oxygen ( 1 O2) in the photodynamic effect, and the half-life degradation time (X0) of DPBF was used to reflect the photodynamic performance. Take 975 μL of DPBF (200 μg / mL) prepared in DMSO, add 25 μL of 1 mg / mL Bi-TCPP, Bi-TCPP@Au-Pt or other metal-porphyrin MOFs, mix well, take 200 μL and add it to a 96-well plate, and then detect the absorbance at 421 nm under illumination at 660 nm (0.5 W / cm 2 ).

[0055] Add 1 mL of deionized water-dispersed Bi-TCPP, Bi-TCPP@Au-Pt and other metal-porphyrin MOFs to a 2 mL centrifuge tube, and use an electronic thermometer to measure the water temperature above the illumination center in real time under 660 nm light irradiation. The concentration of the test substance is 100 μg / mL, and the illumination power is 1 W / cm 2 , and calculate the photothermal conversion efficiency (η).

[0056] The photodynamic and photothermal performance tests of the Bi-TCPP particles and Bi-TCPP@Au-Pt particles prepared in Example 1 are as follows Figure 5 shown. The photodynamic performance of Bi-TCPP and Fe-TCPP under 660 nm light irradiation is much stronger than that of PCN-222, Cu-TCPP and Co-TCPP. After modifying with Au-Pt NPs, the photodynamic performance of Bi-TCPP@Au-Pt is further enhanced. In addition, the photothermal conversion efficiency of Bi-TCPP is 43.58%, which is superior to other MOFs. After modifying with Au-Pt NPs, the photothermal conversion efficiency of Bi-TCPP@Au-Pt slightly increases (44.7%). Therefore, Bi-TCPP@Au-Pt has excellent photodynamic and photothermal performance at the same time.

[0057] 4. Photodynamic and photothermal antibacterial properties of Bi-TCPP@Au-Pt

[0058] Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) were selected as model strains. The bacterial suspension was diluted to 10 7 CFU / mL with LB liquid medium, and Bi-TCPP@Au-Pt at 2 mg / mL was prepared with normal saline and diluted to 50, 100, 150, 200, 250 μg / mL with LB liquid medium. 200 μL of the bacterial suspension was mixed with 200 μL of Bi-TCPP@Au-Pt in a 2 mL centrifuge tube, incubated at 37 °C for 5 min, and irradiated with light at 660 nm (1 W / cm 2 ) for 5 min. Then the bacterial suspension was diluted with PBS and spread on LB agar plates. After overnight incubation in an incubator at 37 °C, the colonies were counted. The results are as Figure 6 shown. Under 660 nm light irradiation, as the concentration of Bi-TCPP@Au-Pt prepared in Example 1 increased, the number of bacterial colonies decreased significantly. When the concentration was 100 μg / mL, the bactericidal rates of Bi-TCPP@Au-Pt against S. aureus and E. coli reached 99.9%.

[0059] 5. Antibacterial performance of Bi-TCPP@Au-Pt based on extracellular electron transfer

[0060] Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) were selected as model strains. The bacterial suspension was diluted to 10 7 CFU / mL with LB liquid medium, and Bi-TCPP@Au-Pt at 2 mg / mL was prepared with normal saline and diluted to 50, 100, 150, 200, 250 μg / mL with LB liquid medium. 200 μL of the bacterial suspension was mixed with 200 μL of Bi-TCPP@Au-Pt in a 2 mL centrifuge tube, and then co-incubated at 37 °C with 120 rpm in a constant temperature shaker in the dark for 4 h. The bacterial suspension was diluted with PBS and spread on LB agar plates. After overnight incubation in an incubator at 37 °C, the colonies were counted. The results are as Figure 7 shown. As the concentration of Bi-TCPP@Au-Pt prepared in Example 1 increased, the number of S. aureus colonies decreased significantly, while the number of E. coli colonies did not change significantly compared with the control group. This indicates that Bi-TCPP@Au-Pt has selectivity for antibacterial based on extracellular electron transfer and is only effective against S. aureus, which may be related to the difference in the redox potential of the cell membranes of E. coli and S. aureus. When the concentration was 50 μg / mL, Bi-TCPP@Au-Pt could kill 99.9% of S. aureus.

[0061] 6. Glucose oxidase activity of Bi-TCPP@Au-Pt

[0062] The DNS reagent was used to detect the glucose content and establish a standard curve. Glucose standard solutions with concentrations of 2, 3, 4, 5, and 6 mM were prepared. 200 μL of the glucose solution was mixed with 800 μL of the DNS reagent, heated in a boiling water bath for 10 min, cooled in the range of 3 - 8 °C for 10 min, and then the OD value at 540 nm was measured. For the determination of the kinetic constants of Gox enzyme, different concentrations of glucose solutions (20, 40, 50, 60, 80, 100 mM) and Bi-TCPP@Au-Pt (1 mg / mL) were prepared with an acetic acid - sodium acetate buffer solution at pH = 5.5. 500 μL of glucose was mixed with 500 μL of Bi-TCPP@Au-Pt, and then incubated at 37.0 °C for 40 min. After centrifugation at 12000 rpm, the supernatant was diluted 2, 4, 5, 6, 8, and 10 times respectively, and the glucose content was determined using the DNS reagent. The enzyme kinetic parameters were fitted and solved according to the Michaelis - Menten equation and the Lineweaver - Burk equation. As Figure 8 shown, the Michaelis constant of the glucose oxidase of Bi-TCPP@Au-Pt prepared in Example 1 was 126.38 mM, and the maximum reaction rate was 6.25×10 -6 M / s.

[0063] 7. Catalase activity of Bi-TCPP@Au-Pt

[0064] A standard curve for detecting H2O2 with Ti(SO4)2 was established. 300 μL of different concentrations of H2O2 (2, 5, 8, 11, 14, 17, 20 mM) was mixed with 300 μL of Ti(SO4)2 (40 mM), then 300 μL of H2SO4 (2 mol / L) was added. After thorough mixing, 200 μL was taken and placed in a 96-well plate at 37 °C, and the OD at 412 nm was measured at 0, 5, 10, 20, and 30 min respectively. For the determination of the kinetic constants of CAT enzyme, different concentrations of H2O2 solutions (4, 10, 16, 22, 28, 34, 40 mM) and Bi-TCPP@Au-Pt (50 μg / mL) were prepared with an acetic acid - sodium acetate buffer solution at pH = 5.5. 600 μL of H2O2 was mixed with 600 μL of Bi-TCPP@Au-Pt, incubated at 37.0 °C for 5 min, and after centrifugation at 12000 rpm, 300 μL of the supernatant was mixed with 300 μL of Ti(SO4)2 and then 300 μL of H2SO4 was added. After mixing, it was placed at 37 °C for 30 min, and the OD at 412 nm was measured. The enzyme kinetic parameters were fitted and solved according to the Michaelis - Menten equation and the Lineweaver - Burk equation. As Figure 9 shown, the Michaelis constant of the catalase of Bi-TCPP@Au-Pt prepared in Example 1 was 107.92 mM, and the maximum reaction rate was 2.21×10-4 M / s.

[0065] 8. In vitro cytotoxicity of Bi-TCPP@Au-Pt

[0066] Prepare Bi-TCPP@Au-Pt with different concentrations using DMEM and stabilize for 48 h. Mouse embryonic fibroblasts (NIH / 3T3) and human umbilical vein endothelial cells (HUVEC) are cultured in DMEM medium in an incubator at 37 °C with 5% CO2. The cell suspension (1×10 5 cells / well) is inoculated into a 96-well plate and incubated for 24 h. Subsequently, the medium is discarded, and Bi-TCPP@Au-Pt prepared with DMEM is added. The OD value at 450 nm is measured using the CCK-8 method after incubation for 24 h and 72 h, respectively. As Figure 10 shown, with the increase in the concentration of Bi-TCPP@Au-Pt prepared in Example 1 and the co-incubation time, the cell viability of the two types of cells gradually decreases. However, after incubation for 72 h at a concentration of 150 μg / mL, the cell viability is still higher than 80%, indicating that Bi-TCPP@Au-Pt has little effect on cell survival at concentrations below 150 μg / mL.

[0067] 9. Hemolytic property of Bi-TCPP@Au-Pt

[0068] Defibrinated sheep blood is taken and washed and centrifuged three times with physiological saline to obtain purified red blood cells, and a 10% red blood cell physiological saline suspension is prepared. In the positive control group, 50 μL of pure red blood cells is mixed with 950 μL of distilled water, and in the negative control group, it is a 5% red blood cell physiological saline suspension. In the experimental group, different concentrations of Bi-TCPP@Au-Pt physiological saline solution are mixed equally with a 10% red blood cell suspension. After co-culture at 37 °C for 1.5 h, it is centrifuged at 2500 rpm / min for 5 min, and the OD value of the supernatant is read at 540 nm using an enzyme-linked immunosorbent assay reader. The results are as Figure 11 shown. When the concentration increases to 150 μg / mL, the hemolysis rate of Bi-TCPP@Au-Pt prepared in Example 1 is still lower than the international standard requirement (5%), indicating that the material has no obvious hemolysis phenomenon.

[0069] 10. In vivo effect of Bi-TCPP@Au-Pt in treating diabetic wounds

[0070] Male C57BL / 6J mice are induced to be type 1 diabetic mice using streptozotocin. Under isoflurane anesthesia, a wound with a diameter of 5 mm is made on the back of each mouse, and 10 810 μL of S. aureus bacterial solution with a concentration of CFU / mL was used for infection, and 24 h after infection was recorded as day 0 (D0). In the NS group, 40 μL of normal saline was dropped on the wound. The Duoderm group covered the wound with a commercial gel dressing. The Bi-TCPP(IR) group was dropped with 40 μL of Bi-TCPP prepared with normal saline at a concentration of 100 μg / mL, and 2 irradiated with visible light at 660 nm for 5 min at a power density of 1 W / cm². Both the Bi-TCPP@Au-Pt and Bi-TCPP@Au-Pt(IR) groups were dropped with 40 μL of Bi-TCPP@Au-Pt prepared with normal saline at a concentration of 100 μg / mL. The Bi-TCPP@Au-Pt(IR) group was 2 irradiated with visible light at 660 nm for 5 min at a power density of 1 W / cm². A total of three doses were administered on days 0, 3, and 5 respectively, and wound images were recorded on days -1, 0, 3, 6, and 9. As Figure 12 shown, after treatment for 9 days, the wound areas of the Bi-TCPP@Au-Pt and Bi-TCPP@Au-Pt(IR) groups were significantly smaller than those of other groups, while the wound healing degree of the Bi-TCPP(IR) group was significantly better than that of the NS group and the Duoderm group. On day 3, the infected wounds of the NS group and the Duoderm group showed obvious deterioration, manifested as necrosis of the surrounding tissues and an increase in the wound area. In contrast, the infected wounds in the experimental groups given the antibacterial materials showed a trend of continuous healing. This indicates that the significant therapeutic effect of Bi-TCPP@Au-Pt on diabetic infected wounds comes from its multiple regulation of anti-infection and enzyme catalytic effects.

[0071] In summary, the Bi-TCPP@Au-Pt particles prepared by the present invention have multiple antibacterial effects and enzyme catalytic properties, can perform multiple regulations on the adverse microenvironment of diabetic wounds, thus effectively promoting the healing of diabetic wounds, and the material has good safety and high biocompatibility.

[0072] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bismuth-based heterogeneous material for promoting diabetic wound healing, characterized in that: The invention comprises a bismuth-based porphyrin metal organic framework, and the surface of the bismuth-based porphyrin metal organic framework is modified with Au-Pt nanoparticles.

2. The method for preparing the bismuth-based heterogeneous material according to claim 1, characterized in that: The following steps are involved: (1) Synthesis of bismuth-based porphyrin metal-organic frameworks by solvothermal method; (2) Au-Pt nanoparticles were modified on the surface of bismuth-based porphyrin metal organic framework by co-reduction method.

3. The method for preparing bismuth-based heterogeneous materials according to claim 2, characterized in that: In step (1), the specific method for synthesizing the bismuth-based porphyrin metal organic framework is as follows: Bi(NO3)3·5H2O and TCPP are dissolved in a solvent, mixed and heated, and the reaction product is washed and dried to obtain a bismuth-based porphyrin metal organic framework.

4. The method for preparing bismuth-based heterogeneous materials according to claim 2, characterized in that: In step (2), the specific method for modifying Au-Pt nanoparticles is as follows: dispersing the bismuth-based porphyrin metal organic framework in deionized water, then adding HAuCl4 and H2PtCl6·6H2O, mixing, adding NaBH4 for co-reduction reaction, washing and drying the reaction product to obtain a bismuth-based heterogeneous material.

5. The method for preparing bismuth-based heterogeneous materials according to claim 3, characterized in that: In step (1), the solvent includes N,N-dimethylformamide and deionized water, and the volume ratio of N,N-dimethylformamide to deionized water is (5-15):(0.5-4).

6. The method for preparing bismuth-based heterogeneous materials according to claim 3 or 5, characterized in that: In step (1), the molar ratio of Bi(NO3)3·5H2O to TCPP is (1.8-2.2):(0.9-1.1); the heating temperature is 100-160°C, and the reaction time is 8-36h; in step (1), the concentration of Bi(NO3)3·5H2O in the solvent is (1-50) mmol / L.

7. The method for preparing bismuth-based heterogeneous materials according to claim 4, characterized in that: In step (2), the bismuth-based porphyrin metal organic framework is dispersed in deionized water, and after ultrasonic dispersion, HAuCl4 and H2PtCl6·6H2O are added. After ultrasonic treatment, a NaBH4 solution prepared in cold water is added at once under ice-water bath and stirring conditions, wherein the concentration of the NaBH4 solution is 1-3 mg / mL, the temperature of the cold water is 4-8°C, the reaction is continued by stirring, and the reaction product is washed and dried to obtain a bismuth-based heterogeneous material.

8. The method for preparing bismuth-based heterogeneous materials according to claim 4, characterized in that: In step (2), the usage ratio of bismuth-based porphyrin metal organic framework to deionized water is (0.05-5) mg:(0.5-2) mL.

9. The method for preparing bismuth-based heterogeneous materials according to claim 4 or 8, characterized in that: In step (2), the mass ratio of bismuth-based porphyrin metal organic framework, HAuCl4, H2PtCl6·6H2O and NaBH4 is (15-25):(0.5-4):(1-8):(0.25-2).

10. Use of the bismuth-based heterogeneous material according to claim 1 or the bismuth-based heterogeneous material prepared by the preparation method according to claims 2 to 9 in preparing a medicine or dressing for promoting diabetic wound healing.

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