A method for preparing TCPP / Emodin composite photocatalyst and its antibacterial application

Abstract

This invention discloses a method for preparing TCPP / Emodin composite photocatalysts and their antibacterial applications, belonging to the field of pharmaceutical antibacterial medicine. Addressing the issues of drug resistance easily induced by traditional antibiotics in treating bacterial infections, performance defects in existing photocatalysts, and insufficient antibacterial capacity of single antibacterial materials, this invention leverages the advantages of tetracarboxyphenylporphyrin (TCPP)—strong visible light capture ability and low photogenerated electron-hole recombination rate—and complements emodin's π-conjugated system and its structural advantage of promoting carrier migration. The two are covalently linked through a chemical coupling mechanism involving EDC / NHS synergistic activation of the carboxyl group. Through steps such as dissolution, mixing reaction, dialysis purification, and freeze-drying, spherical TCPP / Emodin composite nanomaterials with a particle size of 100-500 nm are obtained. This composite material reduces the photogenerated electron-hole recombination rate and improves carrier migration efficiency, efficiently generating ROS under visible light irradiation, and exhibits excellent photodynamic antibacterial properties.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical antibacterial, and relates to the preparation method and antibacterial application of TCPP / Emodin composite nanophotocatalysts. Background Technology

[0002] Bacterial infections are one of the leading causes of death worldwide, with Staphylococcus aureus (Staphylococcus aureus) being a major contributing factor. S.aureus ) and Escherichia coli ( E. coli These two bacteria, representing Gram-positive and Gram-negative bacteria respectively, are common clinical pathogens. Currently, antibiotic therapy is the main treatment for bacterial infections in clinical practice. However, with the widespread use and abuse of antibiotics, the antibacterial activity of existing antibiotics has significantly decreased, leading to a substantial reduction in treatment efficacy. Furthermore, the evolution and spread of multidrug-resistant strains have further exacerbated the clinical treatment challenges. For example, the widespread prevalence of methicillin-resistant Staphylococcus aureus (MRSA) poses a serious challenge to traditional antibacterial strategies. Therefore, developing novel antibacterial treatment regimens that are highly effective, specific, and have a low risk of drug resistance is of significant practical importance and clinical value in solving the challenges of treating clinical bacterial infections.

[0003] In recent years, biomaterials with intelligent responsive properties have shown broad application prospects in the field of anti-infection due to their core advantage of "on-demand activation." Among them, photo-assisted antibacterial strategies have attracted widespread attention due to their advantages such as high controllability and low side effects. This strategy utilizes the localized high heat or reactive oxygen species (ROS) generated by photoresponsive materials under specific wavelength light irradiation to achieve efficient clearance of pathogenic microorganisms, mainly including two categories: photothermal therapy (PTT) and photodynamic therapy (PDT).

[0004] In photocatalysts (PDT) applications, photocatalysts are crucial, but current PDT technologies still have significant limitations: First, the types of photocatalysts used in clinical practice and research are limited. Conventional catalysts, such as traditional organic photosensitizers like phthalocyanines and methylene blue, and traditional inorganic semiconductor photocatalysts like TiO2 and ZnO, generally suffer from low light absorption efficiency in biological tissues, high photogenerated electron-hole recombination rates, and slow in vivo degradation rates. These not only restrict the therapeutic effect on deep tissues but also pose a risk of potential toxicity due to in vivo accumulation. Second, existing single photocatalytic antibacterial materials often suffer from low antibacterial efficiency, failing to meet the clinical needs for treating bacterial infections. Therefore, optimizing the light absorption performance of photocatalysts and accelerating their in vivo degradation rate are the core directions for improvement in the development of photocatalysts for PDT. Summary of the Invention

[0005] To address the technical problems of drug resistance easily induced by traditional antibiotic treatment for bacterial infections, the performance defects of existing PDT photocatalysts, and the insufficient antibacterial ability of single antibacterial materials, this invention provides a method for preparing tetracarboxyphenylporphyrin / emodin (TCPP / Emodin) composite nanophotocatalysts and their antibacterial applications. By chemically coupling, the performance synergy of TCPP and Emodin is achieved, resulting in a composite nanomaterial with high photocatalytic activity, broad antibacterial spectrum, and low drug resistance, providing a novel solution for the clinical treatment of bacterial infections.

[0006] TCPP possesses excellent properties such as strong visible light capture ability, low photogenerated electron-hole recombination rate, and fast photogenerated carrier transfer speed, making it an ideal PDT photocatalytic material. However, it is prone to aggregation in biological systems, leading to insufficient photocatalytic active sites and significantly reducing its antibacterial effect. Emodin, as a natural active traditional Chinese medicine molecule, has biological functions such as inhibiting oxidative stress, anti-inflammation, direct antibacterial activity, and promoting bone regeneration. Its π-conjugated system in its molecular structure can effectively promote carrier generation and enhance migration ability. However, its photocatalytic activity is extremely weak, and it cannot efficiently generate ROS. Relying solely on its own direct bactericidal effect results in low antibacterial efficiency and a slow action rate, making it difficult to quickly eliminate high concentrations of pathogenic bacteria. Based on the unique advantages and functional complementarity of the two materials, this invention constructs a composite nanomaterial by covalently combining TCPP and Emodin through chemical coupling of EDC / NHS synergistically activating carboxyl groups. By utilizing the π-conjugated structure of the two materials, the recombination probability of photogenerated electron-hole pairs is synergistically reduced, and the carrier migration ability is enhanced, thereby achieving highly efficient photodynamic antibacterial activity. This avoids the development of bacterial drug resistance from the mechanism of action and achieves broad-spectrum bactericidal activity against both Gram-positive and Gram-negative bacteria.

[0007] This invention provides a method for preparing TCPP / Emodin composite nanocatalysts, comprising the following steps: (1) TCPP powder and carboxyl activator were added to N,N-dimethylformamide (DMF) solvent and the TCPP and EDC were completely dissolved by magnetic stirring at room temperature to obtain solution A; the carboxyl activator was carbodiimide (EDC). (2) Add emodin powder and N-hydroxysuccinimide (NHS) powder to DMF solvent, and stir magnetically at room temperature to completely dissolve emodin and NHS to obtain solution B; (3) Slowly add solution B to solution A, controlling the dropping rate to ensure the reaction system is fully mixed. After the addition is complete, continue magnetic stirring to complete the composite reaction. (4) Transfer the mixed solution after the reaction to a dialysis bag and dialyze it in deionized water. Change the dialysis fluid every day to completely remove unreacted small molecules and solvents. (5) The dialysis solution was freeze-dried to remove all solvents, and finally a stable TCPP / Emodin composite nanocatalyst was obtained.

[0008] In step (1), the magnetic stirring is performed at a constant speed of 300-800 r / min for 1.5-2.5 h; 100-120 mg TCPP powder and 50-70 mg carbodiimide (EDC) are added to every 30-50 mL of DMF.

[0009] In step (2), 45-55 mg of Emodin powder and 15-25 mg of NHS powder are added to every 8-12 mL of DMF, and the magnetic stirring time is 1.5-2.5 h.

[0010] In step (3), the dropping rate of solution B is 1-3 drops / second, and the volume ratio of solutions A and B is controlled at 4:1 to 5:1; after the dropping is completed, continue magnetic stirring for 5-7 hours.

[0011] In step (4), the dialysis bag is designed to have a molecular weight cutoff of 1000. It is then purified by dialysis in deionized water for 2-4 days, with the external dialysis solution being changed 1-3 times a day.

[0012] The particle size of the composite nanophotocatalyst prepared by the above method can be controlled within 100-500 nm.

[0013] This invention provides the application of the aforementioned TCPP / Emodin composite nanophotocatalyst in antibacterial applications. Specifically, it utilizes PDT to efficiently kill Gram-positive and Gram-negative bacteria under visible light irradiation, effectively targeting common clinically prevalent bacteria. S.aureus (Gram-positive bacteria) and E. coli It has excellent broad-spectrum bactericidal effects against Gram-negative bacteria.

[0014] In this invention, TCPP powder and EDC powder are dispersed in DMF solvent. EDC, as a carboxyl activator, can activate the carboxyl groups in TCPP molecules, providing active sites for subsequent reactions. In this carboxyl activator, Emodin powder is doped into NHS reagent, and the activation synergistic effect of NHS on the carboxyl groups further enhances the reaction efficiency. Subsequently, the two solutions are mixed and stirred at a constant temperature, promoting the covalent bonding of TCPP and Emodin to form a composite system. After the stirring reaction is completed, the TCPP / Emodin composite bionanomaterial is finally constructed through dialysis and freeze-drying. Since both TCPP and Emodin have abundant functional groups (such as carboxyl and hydroxyl groups) on their surfaces and possess π-conjugated structures, the composite structure after chemical coupling endows the material with two major properties: firstly, the π-conjugated structure can effectively reduce the recombination probability of photogenerated electron-hole pairs; secondly, the functional groups can enhance the migration ability of charge carriers, laying the structural foundation for the photocatalytic performance of the material. Under visible light irradiation, the material absorbs visible light energy and undergoes electron transitions, efficiently generating electron-hole pairs. Photogenerated holes possess strong oxidizing properties and can directly oxidize substances on the surface of bacteria; photogenerated electrons can react with water and oxygen in the system to form various highly oxidizing reactive oxygen species (ROS), such as singlet oxygen (ROS). 1 The ROS generated by free radicals such as O2 and hydroxyl radicals (·OH) can oxidize the biomolecules on the bacterial cell membrane, destroying the integrity and permeability of the cell membrane; it can also enter the bacterial cell, oxidize the cytoplasm, and damage DNA and RNA, ultimately leading to the rapid death of bacteria, thereby achieving a highly effective antibacterial treatment effect.

[0015] The beneficial effects of this invention are: (1) Material Structure Design: This method achieves precise control of material morphology and particle size in nanostructure and enhances material interface properties through a multi-step process: First, rod-shaped TCPP powder with photocatalytic activity and layered Emodin powder with inherent bactericidal properties are dissolved together in DMF. A magnetic stirrer is used to ensure uniform dispersion of the two powders, forming a stable mixed system. Then, unreacted impurities in the system are removed by dialysis, followed by freeze-drying to finally construct a spherical TCPP / Emodin composite nanostructure. The two are chemically coupled to form a composite structure. The particle size of this composite nanomaterial can be controlled within the range of 100-500 nm, which is significantly smaller than that of a single component. Figure 2 It can be seen that N, C, and O elements are uniformly distributed within the material, with no obvious agglomeration. The reduction in particle size not only gives the material a larger specific surface area but also makes it exhibit a typical nanoscale effect. On the one hand, it can provide more photocatalytic active sites and improve photoresponse efficiency; on the other hand, it enhances the material's adsorption capacity for bacteria, achieving efficient capture of pathogenic microorganisms and laying the foundation for subsequent sterilization processes.

[0016] (2) Synergistic Performance Enhancement: The composite of nano-TCPP and Emodin is not a simple performance superposition, but rather a synergistic enhancement of photocatalytic performance through structural complementarity, significantly improving photocatalytic antibacterial performance. Both are rich in functional groups (such as carboxyl and hydroxyl groups) on their surfaces and possess π-conjugated systems. This structural characteristic enables them to efficiently generate electron-hole pairs under visible light irradiation, accelerating the transfer rate of photogenerated carriers, thereby enabling the formation of various hydroxyl radicals and other highly oxidizing ROS with water and oxygen. In addition, TCPP and Emodin may form a Schottky junction at the interface. This interface structure can further promote the directional migration of electrons and reduce the interface resistivity, thereby significantly improving the separation efficiency of photogenerated carriers. Due to the synergistic effect of the two, the photocatalytic performance of the material is improved, the photogenerated electrons and holes are efficiently separated, the yield and generation efficiency of ROS are enhanced, and the destruction efficiency of biomolecules inside and outside bacterial cells is improved, thereby efficiently killing bacteria.

[0017] (3) Bactericidal Coverage: Gram-positive and Gram-negative bacteria are the main pathogens causing clinical bacterial infections. Due to differences in cell wall structure, their sensitivity to traditional antibacterial agents often differs significantly, making it difficult for a single antibacterial material to achieve comprehensive coverage. The TCPP / Emodin nanomaterials prepared in this invention rely on the synergistic effect of TCPP and Emodin to stably generate ROS under visible light assistance. These reactive oxygen species have non-specific oxidative damage capabilities, which can penetrate the thick peptidoglycan cell wall of Gram-positive bacteria and also destroy the outer membrane barrier of Gram-negative bacteria. Thus, they exhibit highly efficient killing ability against both types of pathogens and have excellent broad-spectrum bactericidal ability, which can better meet the treatment needs of complex infections. Attached Figure Description

[0018] Figure 1 These are SEM images of TCPP, Emodin, and TCPP / Emodin from Example 1; Figure 2 This is the EDS image of TCPP / Emodin in Example 1; Figure 3 The results are the photocatalytic performance experiments of TCPP, Emodin, and TCPP / Emodin in Example 1, including: (a) impedance experiments of TCPP, Emodin, and TCPP / Emodin; (b) photocurrent generation experiments of TCPP, Emodin, and TCPP / Emodin; (c) generation of reactive oxygen species (·OH) by TCPP, Emodin, and TCPP / Emodin; and (d) generation of ·O2 by TCPP, Emodin, and TCPP / Emodin. - Experimental results; Figure 4The results of the TCPP, Emodin, and TCPP / Emodin broad-spectrum antibacterial experiments under light irradiation in Example 1 are as follows: (a) S.aureus (a) Results of the plate coating experiment; (b) E. coli Results of the plate coating experiment; Figure 5 Here are SEM images of bacteria under light irradiation from Example 1: S.aureus and E. coli SEM images. Detailed Implementation

[0019] To better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, the scope of protection of the present invention is not limited to the scope shown in the embodiments. Example 1

[0020] A method for preparing TCPP / Emodin composite photocatalysts and their antibacterial application was implemented. The preparation method was carried out according to the following steps: Step 1: Weigh 112 mg TCPP and 60 mg EDC and add them to 40 mL DMF. Stir magnetically (500 rpm / min) for 2 h at room temperature until the powder is completely dissolved to obtain solution A.

[0021] Step 2: Weigh 52 mg Emodin and 20 mg NHS powder and add them to 10 mL DMF. Stir magnetically (500 rpm / min) for 2 h at room temperature until the powder is completely dissolved to obtain solution B.

[0022] Step 3: Slowly add solution B to solution A at a rate of 2 drops / second (A:B volume ratio 4:1). After the addition is complete, continue magnetic stirring at room temperature for 6 hours to complete the composite reaction.

[0023] Step 4: Transfer the reacted mixture to a dialysis bag with a molecular weight cutoff of 1000 and dialyze it in deionized water for purification for 3 days, changing the dialysis fluid 3 times a day to completely remove unreacted small molecules and solvents. Step 5: The dialyzed solution is freeze-dried to remove all solvent, finally obtaining a stable TCPP / Emodin composite photocatalyst with a particle size between 100-500 nm. Example 2

[0024] A method for preparing TCPP / Emodin composite photocatalysts, comprising the following steps: Step 1: Weigh 120 mg TCPP and 70 mg EDC and add them to 50 mL DMF. Stir magnetically at 800 r / min for 2.5 h at room temperature until completely dissolved to obtain solution A.

[0025] Step 2: Weigh 55 mg Emodin and 25 mg NHS and add them to 12 mL DMF. Stir magnetically at room temperature for 2.5 h until completely dissolved to obtain solution B.

[0026] Step 3: Add solution B to solution A at a rate of 3 drops / second (A:B volume ratio 4.17:1), and stir magnetically at room temperature for 7 hours after addition to complete the reaction.

[0027] Step 4: Transfer the mixed solution to a dialysis bag with a molecular weight cutoff of 1000, and dialyze in deionized water for 4 days, changing the dialysis fluid 3 times a day to completely remove unreacted small molecules and solvents.

[0028] Step 5: The dialyzed solution is freeze-dried to remove all solvent, finally obtaining a stable TCPP / Emodin composite photocatalyst with a particle size of 300-500 nm.

[0029] The performance of the TCPP / Emodin composite photocatalyst obtained in Example 1 was tested. The material's microstructure, elemental composition, photocatalytic performance, and antibacterial test results are attached. Figures 1-5 As shown, Figure 1 SEM images of TCPP, Emodin, and TCPP / Emodin show the significant differences in their microstructures. The images reveal that TCPP exhibits a rod-like structure, Emodin a layered stacked state, while the TCPP / Emodin composite material shows a marked morphological transformation, forming an irregular spherical structure with a diameter of approximately 100 nm-500 nm, without any large aggregates. This indicates that the two components achieved uniform fusion during the composite process, successfully constructing the target nanostructure. To clarify the elemental composition and distribution of the TCPP / Emodin composite nanomaterial, EDS characterization was performed, and the results are shown in Figure 2. The main constituent elements of this composite nanomaterial are N, C, and O, and these three elements are evenly distributed. C mainly originates from the molecular framework of TCPP and Emodin, N is a characteristic element of the TCPP porphyrin ring, and O comes from functional groups such as hydroxyl and carboxyl groups on the surfaces of the two components. This result further confirms that TCPP and Emodin achieve uniform molecular-level binding during the composite process, providing structural assurance for the synergistic effect of the material's subsequent photocatalytic and antibacterial properties. Figure 3The experimental results for the photocatalytic performance of TCPP, Emodin, and TCPP / Emodin are presented. Charge transfer impedance spectroscopy (EIS) is an important data point for evaluating the charge transfer capability of materials. The diameter of the Nyquist circle is positively correlated with the charge transfer resistance; the smaller the diameter, the lower the charge transfer resistance at the material interface, and the higher the separation and conversion efficiency of photogenerated carriers. Figure 3 As shown in Figure a, the experimental results show that Emodin exhibits a large impedance value, indicating that its charge transfer process is significantly hindered; while TCPP / Emodin has the smallest impedance value, indicating that this material has excellent charge transfer capability. Transient photocurrent response tests further corroborate this conclusion. Figure 3 (b) Emodin exhibits a weaker photocurrent, reflecting the ease with which its photoexcited carriers recombine; while TCPP shows a stronger transient photocurrent, indicating a significant improvement in the separation efficiency of photogenerated carriers at the TCPP interface. Notably, the photocurrent intensity of TCPP / Emodin is much higher than that of ZnTCPP, suggesting that the synergistic effect of TCPP and Emodin can enhance space charge separation, which is beneficial to the efficient generation of reactive oxygen species. This invention uses the degradation degree of methyl violet (MV) and nitro blue tetrazolium (NBT) as evaluation indicators to quantitatively analyze the ·OH and ·O2 of the samples under visible light irradiation. - The ability to generate. For example... Figure 3 c(MV), Figure 3 As shown in d(NBT), compared with the blank control, the absorption intensities of TCPP and Emodin at 580 nm (MV) and 260 nm (NBT) are reduced, indicating that the two materials produce a small amount of ·OH and ·O2 under visible light irradiation. - In contrast, the absorption peak attenuation of TCPP / Emodin at 580 nm and 260 nm was significantly greater than that of the previous two groups, indicating that under light irradiation, TCPP / Emodin more readily promotes charge transfer, improves carrier separation efficiency, and thus generates a large amount of reactive oxygen species. This means that TCPP / Emodin has the best visible light photocatalytic activity. Based on the above EIS, transient photocurrent, and reactive oxygen species detection results, it can be concluded that the TCPP / Emodin composite system has the best visible light photocatalytic activity. To systematically evaluate the antibacterial properties of the TCPP / Emodin composite material, Staphylococcus aureus, as a representative Gram-positive bacterium, was selected to evaluate the antibacterial activity of TCPP / Emodin. Figure 4As shown in Figure a, none of the samples exhibited significant antibacterial effects under no-light conditions. After 10 minutes of light exposure, the colony counts of all samples decreased significantly, but TCPP and Emodin still showed low levels of antibacterial activity. TCPP's antibacterial efficiency was 61.70%, likely due to the generation of a small amount of reactive oxygen species that kill bacteria under light. Emodin's antibacterial efficiency was slightly higher than TCPP at 63.96%, as Emodin, being a natural anthraquinone compound, possesses multiple functions including disrupting the biofilm matrix and direct bactericidal activity. However, both only achieved partial bacterial clearance and did not achieve the desired antibacterial effect. Nevertheless, under the same conditions, the TCPP / Emodin composite material showed the most significant bactericidal effect, with an antibacterial efficiency of 96.96% against Staphylococcus aureus, significantly superior to the two individual materials. To verify the universality of the composite material's antibacterial properties, this study further conducted antibacterial experiments using Escherichia coli, a representative Gram-negative bacterium, as the test subject. The results are as follows... Figure 4 As shown in b. Experimental data show that the TCPP / Emodin composite material exhibits the most significant bactericidal effect under light irradiation, with an antibacterial efficiency as high as 98.81%. The above experiments demonstrate that this composite material possesses excellent broad-spectrum bactericidal properties under photo-assisted effects. To verify the antibacterial effect at the microscopic morphological level, this study observed the changes in bacterial cell structure under visible light irradiation for 10 minutes using scanning electron microscopy (SEM). The results are shown in b. Figure 5 As shown in the image, varying degrees of damage to bacterial cell membranes further confirmed the results of the plate experiment. SEM images revealed that the bacteria in the blank control group maintained their typical intact morphology: Staphylococcus aureus was regularly spherical, and Escherichia coli was typically rod-shaped. The cell membranes of both types of bacteria were smooth, flat, and structurally intact, without obvious damage or deformation. In stark contrast to the control group, the bacteria treated with the TCPP / Emodin composite material exhibited severe structural damage: loss of cell membrane integrity, obvious wrinkles and ruptures on the surface, and an overall shriveled and dried-up state, indicating that TCPP / Emodin possesses excellent broad-spectrum bactericidal ability.

[0030] In summary, this study successfully prepared TCPP / Emodin composite materials via solvent dialysis. This material not only exhibits excellent photoresponse characteristics, efficiently generating reactive oxygen species and enhancing charge separation efficiency under visible light excitation, but also demonstrates significant broad-spectrum antibacterial properties in antibacterial experiments, providing reliable experimental evidence and research ideas for the development of novel photo-assisted antibacterial materials.

Claims

1. A method for preparing a TCPP / Emodin composite nanocatalyst, characterized in that... Includes the following steps: (1) Add TCPP powder and carboxyl activator to DMF solvent, and stir magnetically at room temperature to completely dissolve TCPP and carboxyl activator to obtain solution A; (2) Add Emodin powder and N-hydroxysuccinimide powder to DMF solvent, and stir magnetically at room temperature to completely dissolve emodin and N-hydroxysuccinimide to obtain solution B; (3) Slowly add solution B to solution A, controlling the dropping rate to ensure the reaction system is fully mixed. After the addition is complete, continue magnetic stirring to complete the composite reaction. (4) Transfer the mixed solution after the reaction to a dialysis bag and dialyze it in deionized water. Change the dialysis fluid every day to completely remove unreacted small molecules and solvents. (5) The dialysis solution was freeze-dried to remove all solvents, and finally a stable TCPP / Emodin composite nanocatalyst was obtained.

2. The preparation method of the TCPP / Emodin composite nanocatalyst according to claim 1, characterized in that, The carboxyl activator is carbodiimide.

3. The preparation method of the TCPP / Emodin composite nanocatalyst according to claim 1, characterized in that, In step (1), the magnetic stirring is performed at a constant speed of 300-800 r / min for 1.5-2.5 h.

4. The preparation method of the TCPP / Emodin composite nanocatalyst according to claim 1, characterized in that, In step (1), 100-120 mg of TCPP powder and 50-70 mg of carbodiimide are added to every 30-50 mL of DMF.

5. The preparation method of the TCPP / Emodin composite nanocatalyst according to claim 1, characterized in that, In step (2), 45-55 mg of Emodin powder and 15-25 mg of NHS powder are added to every 8-12 mL of DMF, and the magnetic stirring time is 1.5-2.5 h.

6. The preparation method of the TCPP / Emodin composite nanocatalyst according to claim 1, characterized in that, In step (3), the dropping rate of solution B is 1-3 drops / second, and the volume ratio of solutions A and B is controlled at 4:1 to 5:1; after the dropping is completed, continue magnetic stirring for 5-7 hours.

7. The preparation method of the TCPP / Emodin composite nanocatalyst according to claim 1, characterized in that, In step (4), the dialysis bag is designed to have a molecular weight cutoff of 1000. It is then purified by dialysis in deionized water for 2-4 days, with the external dialysis solution being changed 1-3 times a day.

8. The preparation method of the TCPP / Emodin composite nanocatalyst according to claim 1, characterized in that, The particle size of the composite nanophotocatalyst is 100-500 nm.

9. A TCPP / Emodin composite nanocatalyst prepared by the method according to any one of claims 1 to 8.

10. The application of the TCPP / Emodin composite nanocatalyst according to claim 9 in antibacterial activity.

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