Carbon dots with photothermal and photodynamic dual phototherapy performance and preparation method and application thereof

Abstract

The application belongs to the technical field of antibacterial treatment, and particularly relates to carbon dots with photothermal and photodynamic dual-light therapy performance and a preparation method thereof. The application uses quaternary ammonium salt with antibacterial property as a carbon source, and the prepared carbon dots can retain the antibacterial property. Meanwhile, by doping copper ions, the absorption of the carbon dots in the near-infrared region is increased, the photothermal property is improved, and the bacterial damage is facilitated. In addition, the copper ions also have antibacterial property. On the basis of the bacterial killing mechanism of the quaternary ammonium salt, the PDT and PTT synergistic treatment is realized under single near-infrared wavelength excitation, which is helpful to overcome the drug resistance problem and has good application potential in the antibacterial field.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of antibacterial therapy, and relates to a kind of preparation of carbon dots with photothermal photodynamic therapy antibacterial performance and its application in antibacterial. BACKGROUND

[0002] A series of complications caused by bacterial infection, such as pneumonia, meningitis, skin ulcer and other diseases, pose a great threat to human health. Common bacterial infection on wound surface is one of the obstacles to treat such diseases. In order to solve this problem, antibiotics, antibacterial peptides and quaternary ammonium salt compounds have been studied and widely used. Among them, antibiotics are widely developed as effective antibacterial drugs. However, with the continuous emergence of drug-resistant bacteria, many antibiotics become less and less effective in treating bacterial infections, which can lead to prolonged infection time, increased cost, and even increased mortality of common bacterial infections. However, the development of new antibiotics faces problems such as high development cost and short effective time, so the development of antibiotics cannot keep up with the emergence speed of drug-resistant bacteria, and cannot fundamentally solve the problem of bacterial drug resistance. Therefore, it is of great practical significance to develop a new type of antibacterial drug to replace traditional antibiotics to treat bacterial infections.

[0003] In recent years, photothermal therapy (PTT) is considered to be a very effective method for antibacterial, disinfection and tumor treatment due to its unique advantages such as non-invasive, targeted selective treatment, and small side effects. It is a treatment method that destroys the cell membrane and related proteins of bacteria by converting light energy into heat energy through photosensitizers in the presence of appropriate light sources (usually near-infrared light in the range of 780 nm to 1100 nm). Compared with traditional antibiotic therapy, PTT has many advantages such as broad-spectrum antibacterial activity against a variety of pathogens (even antibiotic-resistant bacteria and bacteria in biofilms), short treatment time (only a few minutes), and negligible bacterial resistance.

[0004] Photodynamic antibacterial (PDT) is a new non-invasive antibacterial therapy. PDT can activate photosensitizers at the target site under the excitation of a visible light source with a specific wavelength (usually 660 nm), produce active oxygen with cytotoxicity, oxidize various biological macromolecules that make up the cell structure, such as proteins, nucleic acids, lipids, etc., cause the cell structure to be destroyed from the inside out, and thus cause the bacteria to die.

[0005] However, single PTT can damage normal tissue cells due to local overheating, and single PDT also requires a large amount of ROS to kill bacteria, and excessive ROS can cause inflammation, fibrosis and necrosis of normal cells. Therefore, PTT and PDT have great application potential for synergistic antibacterial because PTT does not depend on oxygen and can generate heat under near-infrared light irradiation, which can make up for the defects of long-time PDT in bactericidal efficiency, thereby achieving better bactericidal effect.

[0006] High polymer nanomaterials, gold nanorods, graphene, etc. have good light-heat conversion performance, and convert light energy into heat energy for sterilization. Carbon-based nanomaterials (carbon nanotubes, carbon nanoparticles, carbon dots, etc.) are the most widely studied and excellent light-heat agents. Such photosensitizers have the advantages of good light stability, high light-heat conversion efficiency, good biocompatibility, green safety and low cost. At present, the research on carbon dot antibacterial is mainly in PTT or PDT single mode, and a few reports use carbon dots combined with other photosensitizers to form a composite photosensitizer, realize the combination of photothermal PTT and photodynamic PDT synergistic effect, or use a lower wavelength light source (660nm) to irradiate the carbon dots to produce an effect. Therefore, developing a new type of carbon dot with photothermal and photodynamic dual light therapy performance, which is green and safe and can be irradiated under near-infrared light, is an important research direction for antibacterial therapy. SUMMARY

[0007] Therefore, the first object of the present application is to provide a carbon dot with photothermal and photodynamic dual light therapy performance to solve the problems in the prior art.

[0008] It should be noted that carbon dots have good water solubility, high stability, low toxicity, excellent biocompatibility and low environmental impact, and can be applied in various system environments, such as carbon dots can be loaded in hydrogel, aerogel, fiber membrane or prepared into a carbon dot-containing aqueous solution for medical field.

[0009] Therefore, the present application is committed to developing a new type of carbon dot with photothermal and photodynamic synergistic antibacterial performance to realize bacterial infection treatment under safe near-infrared light irradiation of normal tissue, to solve the shortcomings of single mode treatment of bacterial infection with comprehensive advantages, and the synergistic antibacterial material and treatment mode are of great significance for treating bacterial infection.

[0010] In order to achieve the above object, the technical scheme adopted by the present application is as follows:

[0011] A carbon dot with photothermal and photodynamic dual light therapy performance, the carbon dot is a carbon dot with PDT and PTT synergistic antibacterial prepared by one-step hydrothermal method; the carbon dot is prepared by using quaternary ammonium salt as carbon source and loading copper ions; and the carbon dot is CuQACDs.

[0012] It is further needed to be explained that single PTT can destroy normal tissue cells due to local overheating and other problems, and single PDT also needs a large amount of ROS to kill bacteria, and excessive ROS can cause inflammation, fibrosis and necrosis of normal cells. Carbon dots (CDs) with photo-thermal conversion properties can increase local temperature under near-infrared light excitation, causing bacterial DNA damage and protein denaturation. Although the emergence of drug-resistant bacteria is avoided, due to its absorption of light usually in the short wave region, the application conditions are relatively harsh, and there is also a risk of secondary damage to human normal tissues and cells, which also limits its wide use in clinical practice.

[0013] Therefore, the quaternary ammonium salt with antibacterial properties is used as a carbon source in the present application, and the prepared carbon dots can retain their antibacterial properties, and by doping copper ions, the absorption of carbon dots in the near-infrared region is increased, and the photo-thermal properties are improved, which is beneficial to bacterial damage. In addition, copper ions also have antibacterial properties, and on the basis of combining the mechanism of killing bacteria by quaternary ammonium salt, PDT and PTT synergistic treatment is realized under single near-infrared wavelength excitation, which helps to overcome the problem of drug resistance and has good application potential in the field of antibacterial.

[0014] Specifically, carbon dots are a kind of ultra-fine, dispersed, quasi-spherical carbon nanoparticles with a size of less than 10 nm, which can destroy the cell membrane structure through physical action and induce increased ROS to cause oxidative damage to achieve the purpose of eliminating bacteria; in addition, part of the CDs have photo-thermal conversion properties, which can increase the local temperature under light excitation, causing bacterial DNA damage and protein denaturation. The p-p interaction of the C=C bond of carbon dots makes the absorption of most carbon dots usually in the short wavelength region, and compared with other wavelengths of light, near-infrared light (780-2526 nm) has better tissue penetration and minimal damage to the skin and tissues. In addition, the bacterial cell membrane contains lipopolysaccharide and phosphatidic acid components, and the surface presents a negative charge, so the positively charged CDs are easily adsorbed on the surface of the bacterial cell by electrostatic interaction, thereby more effectively killing bacteria.

[0015] Therefore, by doping positively charged copper ions to modify the carbon dots, on the one hand, the absorption of carbon dots in the near-infrared region is enhanced, and the near-infrared photo-thermal properties are improved; on the other hand, the copper ion-doped carbon dots also retain the strong bactericidal ability of copper ions themselves, and the antibacterial properties of the carbon dots are enhanced.

[0016] In addition, quaternary ammonium salt (QAC) as a kind of chemical reagent widely used in antimicrobial field, has extensive killing effect on microorganisms such as algae, bacteria, fungi, viruses and the like. It can realize antibacterial effect through the positive nitrogen atom and hydrophobic long chain in its structure. Among them, the nitrogen atom is combined with phosphatidic acid in cell membrane, and the hydrophobic tail penetrates the hydrophobic structure inside the cell membrane, so as to realize the destruction of cell membrane. Since part of carbon dots will retain the active structure in raw materials, QAC is selected as carbon source, so that carbon dots retain the active groups of QAC, and carbon dots have certain antibacterial performance.

[0017] The second object of the present application is to provide a preparation method of carbon dots with photothermal and photodynamic dual light therapy performance.

[0018] In order to achieve the above object, the present application adopts the following technical scheme:

[0019] A preparation method of carbon dots with photothermal and photodynamic dual light therapy performance, the method specifically comprises the following steps:

[0020] The copper salt and quaternary ammonium salt are weighed and added into water for stirring and dissolving. Then, hydrothermal reaction is carried out, and after the reaction is completed, the solution is left to room temperature, filtered, purified by dialysis and freeze-dried to obtain the carbon dots with photothermal and photodynamic dual light therapy performance.

[0021] It is worth noting that the present application discloses a one-step hydrothermal method for preparing carbon dots with PDT and PTT synergistic antibacterial performance. The quaternary ammonium salt with antibacterial property is used as carbon source, and the antibacterial performance is retained. At the same time, the copper ions with antibacterial property are loaded, which not only improves the photothermal performance of carbon dots, but also enhances the antibacterial effect. The present application not only solves the problem of drug resistance caused by traditional antibiotic treatment of bacterial infection, but also solves the shortcomings and problems of PDT and PTT single therapy, such as low antibacterial efficiency of PTT at low temperature, and different wavelength excitation required for PDT and PTT.

[0022] Alternatively, the copper salt is copper chloride dihydrate, copper sulfate, copper carbonate or copper nitrate, the quaternary ammonium salt is allyltrimethylammonium chloride, bisquid dimethylammonium chloride or bisalkyl dimethylammonium chloride, and the mass ratio of the copper salt to the quaternary ammonium salt is 1:5-3:1.

[0023] Alternatively, the hydrothermal reaction temperature is 150-210 DEG C, and the hydrothermal reaction time is 3-8 h; preferably, the hydrothermal reaction temperature is 180 DEG C, and the hydrothermal reaction time is 6 h.

[0024] Alternatively, the concentration of the solution is 0.25-2 mg / mL, and the laser irradiation parameters are as follows:

[0025] In the range of 0.5-2.0 W / cm 2 , 808 nm laser irradiation for 5-20 min.

[0026] The third object of the present application is to provide the application of carbon dots with photothermal and photodynamic dual light therapy performance in antibiosis as described above.

[0027] Compared with the prior art, the carbon dots with photothermal and photodynamic dual light therapy performance and the preparation method and application thereof have the following excellent effects:

[0028] 1) The quaternary ammonium salt with good antibacterial activity is used as a carbon source, and the carbon dots are synthesized by a simple one-step hydrothermal method; the prepared carbon dots not only retain the original antibacterial activity of the quaternary ammonium salt, but also exhibit excellent optical performance of the carbon dots.

[0029] 2) In the present application, the loading of copper ions enhances the absorption of carbon dots in the near-infrared region, improves the near-infrared photothermal performance, and at the same time, the copper ion-doped carbon dots also retain the strong bactericidal ability of copper ions themselves, and enhance the antibacterial property of the carbon dots.

[0030] 3) Compared with the traditional antibiotic therapy, the CuQACDs prepared in the present application exhibit a synergistic antibacterial mechanism of photothermal and photodynamic therapy, and combine the photothermal and photodynamic therapy modes to play a synergistic effect.

[0031] 4) Compared with the dual light source excitation of single photothermal treatment under near-infrared excitation and single photodynamic treatment under visible light excitation, the CuQACDs prepared in the present application can realize the synergistic treatment effect of photothermal and photodynamic therapy at the same time only by excitation at a single wavelength (near-infrared 808 nm), which is more simple and efficient. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0033] Figure 1 Figure 1 is a transmission electron microscope (TEM) image of CuQACDs; (A) is a TEM image of CuQACDs with a scale of 20 nm (the inset is a nanoparticle size distribution graph of CuQACDs); (B) is a high-resolution TEM image of CuQACDs with a scale of 5 nm (the line mark is the lattice spacing of CuQACDs).

[0034] Figure 2 Figure 2 is a temperature-time curve of 1.5mg / mL CuQACDs aqueous solution with different raw material ratios under 1.5W / cm 2 , 808nm laser irradiation.

[0035] Figure 3 Photothermal properties of CuQACDs; (A) CuQACDs aqueous solutions of different concentrations at 1.5 W / cm² 2 (A) Temperature change over time under 808nm laser irradiation; (B) Temperature change over time of 1.5mg / mL CuQACDs aqueous solution under 808nm laser irradiation at different powers; (C) Temperature change over time of 1.5mg / mL CuQACDs aqueous solution after five photothermal cycles, with irradiation conditions of 1.5W / cm². 2 Irradiate with an 808nm laser for 10 minutes, then turn off the laser and cool for 20 minutes. Repeat this process five times.

[0036] Figure 4 Different concentrations of CuQACDs aqueous solutions were tested at 1.5 W / cm². 2 Infrared thermal imaging image showing the temperature change over time under 808nm laser irradiation.

[0037] Figure 5 Photodynamic properties of CuQACDs; (A) UV absorption spectra of CuQACDs and DPBF mixtures under laser irradiation at different times; (B) Absorbance values ​​of each sample and DPBF mixture at 430 nm over time and linear fitting results; irradiation condition: 1.5 W / cm². 2 Irradiate with an 808nm laser for 10 minutes.

[0038] Figure 6 Figure 1 shows the extracellular reactive oxygen species (ROS) production capacity of CuQACDs; (A) CuQACDs use TEMP as a... 1 (A) ESR spectrum of O2 scavenger; (B) ESR spectrum of CuQACDs with DMPO as ·OH scavenger (sample concentration 1.5 mg / mL, irradiation conditions 1.5 W / cm²). 2 Irradiation with an 808nm laser for 10 minutes.

[0039] Figure 7 Figure 1 shows the reactive oxygen species (ROS) generation capacity of CuQACDs in bacterial cells; (A) DCFH-DA fluorescence intensity of Escherichia coli under different treatment conditions; (B) DCFH-DA fluorescence intensity of Staphylococcus aureus under different treatment conditions.

[0040] Figure 8 Photographs of Staphylococcus aureus bacterial colonies after treatment with different concentrations of CuQACDs.

[0041] Figure 9 Photographs of Escherichia coli colonies after treatment with different concentrations of CuQACDs. Detailed Implementation

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0043] Herein, the term "embodiment" is used as "exemplary" to explain any embodiment, which is not necessarily construed as superior or better than other embodiments. In the performance index test of the embodiments of the present application, unless otherwise specified, the conventional test method in the art is adopted. It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the disclosure of the present application.

[0044] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the present application belongs; and the test methods and technical means not specially noted in the present application refer to the experimental methods and technical means commonly used by those skilled in the art.

[0045] In order to better illustrate the content of the present application, a large number of specific details are given in the specific embodiments below. Those skilled in the art should understand that the present application can also be implemented without some specific details. In the embodiments, some methods, means, instruments, equipment and the like which are well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0046] The technical features disclosed in the embodiments of the present application can be combined in any way without conflict, and the technical solutions obtained by the combination belong to the disclosure of the embodiments of the present application.

[0047] In order to better understand the present application, the following embodiments are further specifically described below, but it should not be understood as limiting the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above disclosure of the present application are also regarded as falling within the scope of protection of the present application.

[0048] Embodiment:

[0049] Table 1: Different raw materials, reaction conditions and ratio of CuQACDs preparation

[0050]

[0051] Note: a represents copper carbonate; b represents dialkyldimethylammonium chloride; without superscript is copper chloride dihydrate and allyltrimethylammonium chloride; CuQACDs-1, CuQACDs-2 and CuQACDs-3 are two kinds of raw materials of quaternary ammonium salt and copper salt, which are matched according to the same molar ratio.

[0052] Example 1:

[0053] Take 0.2557 g of copper chloride dihydrate and 0.2034 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 180°C for 6 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm laser for 10 min. 2

[0054] Example 2:

[0055] Take 0.1853 g of copper carbonate and 0.2034 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 180°C for 6 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm laser for 10 min. 2

[0056] Example 3:

[0057] Take 0.2557 g of copper chloride dihydrate and 0.5430 g of dialkyldimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 180°C for 6 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm laser for 10 min. 2

[0058] Example 4:

[0059] Take 0.2557 g of copper chloride dihydrate and 0.4068 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 180°C for 6 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm laser for 10 min. 2

[0060] Example 5:​​​​

[0061] Take 0.5114 g of copper chloride dihydrate and 0.2034 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 180°C for 6 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm for 10 min. 2 2

[0062] Example 6:

[0063] Take 0.2557 g of copper chloride dihydrate and 0.2034 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 210°C for 6 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm for 10 min. 2

[0064] Example 7:

[0065] Take 0.2557 g of copper chloride dihydrate and 0.2034 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 180°C for 8 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm for 10 min. 2 2

[0066] Example 8:

[0067] Take 0.2557 g of copper chloride dihydrate and 0.2034 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for hydrothermal reaction at 180°C for 8 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 0 mg / mL solution after freeze-drying for 48 h. Irradiate at 1.5 W / cm2, 808 nm for 10 min. 2

[0068] Example 9:

[0069] ​​Take 0.2557 g of copper chloride dihydrate and 0.2034 g of allyl trimethyl ammonium chloride, put into a 50 mL beaker, add 15 mL of deionized water, and stir magnetically at room temperature for 15 min until completely dissolved. Transfer into a 25 mL reactor for 180℃ hydrothermal reaction for 8 h, let the reaction stand to room temperature, filter using a 0.45 μm filter head, purify the sample by dialysis for 12 h, and prepare a 1.5 mg / mL solution after freeze-drying for 48 h. Irradiate with a 0.5 W / cm 2 808 nm laser for 10 min.

[0070] In order to further verify the superiority of the present technology, the inventors made structural characterization and performance determination on the prepared carbon dots, and the specific content is as follows:

[0071] As shown by the TEM image of Figure 1 (A), the CuQACDs carbon dots are spherical nanoparticles with good dispersity. The inserted figure shows the particle size distribution graph of CuQACDs, and from the graph, it can be seen that the diameter is in the range of 3-7 nm with Gaussian distribution, and the peak value of the fitting curve is about 4.8 nm, indicating that the CuQACDs have a relatively uniform size distribution. Figure 1 (B) is the HRTEM image of CuQACDs, as indicated in the figure, the CuQACDs have a lattice spacing of 0.21 nm, corresponding to the (100) crystal plane of graphene, indicating the successful synthesis of the carbon dots.

[0072] As shown in Figure 2 , the concentrations of the three samples are all 1.5 mg / mL, and after irradiation with a 1.5 W / cm 2 808 nm laser for 10 min, the highest temperature of Example 1 can only reach 46.4℃, which cannot reach the temperature for efficient bacterial killing, the highest temperature of Example 5 can reach 57.2℃, and the temperature rising speed is relatively fast, although Example 4 can reach 50℃, the temperature rising speed is relatively slow, and the photothermal conversion efficiency is relatively low, therefore, Example 5 with the fastest temperature rising speed and showing good photothermal performance is selected as the best scheme, and the subsequent photothermal performance research is all around Example 5.

[0073] As shown in Figure 3 (A) and Figure 4 , taking Example 8 as a blank control, the photothermal performance of CuQACDs solutions with different concentrations is investigated under the irradiation of a 1.5 W / cm 2The photothermal performance under 808nm laser irradiation was investigated. As the concentration of CuQACDs increased from 0 mg / mL to 2 mg / mL, the highest achievable temperatures for each solution were 34.7℃, 39.0℃, 44.5℃, 49.3℃, 55.1℃, and 63.9℃, respectively. Both 1.5 mg / mL and 2 mg / mL solutions reached 50℃ within 10 minutes of laser irradiation, demonstrating effective bacterial killing and exhibiting good heating rates. A 1.5 mg / mL CuQACDs solution was selected as the sample to explore the photothermal performance under 808nm laser irradiation at this concentration. Figure 3 As shown in (B), the irradiation power is 0.5 W / cm². 2 (Example 9), 1.0 W / cm 2 1.5W / cm 2 (Example 1) and 2.0 W / cm 2 After 10 minutes of laser irradiation, the highest temperatures of the sample solutions in each group were 35.8℃, 43.9℃, 54.9℃, and 61.0℃, respectively. Considering the maximum laser irradiation power that the skin can tolerate is 1.5 W / cm²,... 2 Furthermore, at this power level, the CuQACDs solution can reach a temperature suitable for antibacterial treatment; therefore, 1.5 W / cm² was chosen. 2 This is the optimal laser irradiation power. For example... Figure 3 As shown in (C), after five photothermal cycles, CuQACDs maintained similar heating rates and reached 55℃ within 10 minutes, indicating good thermal reproducibility and photothermal stability. These experimental results demonstrate that CuQACDs can effectively convert laser energy into heat. Figure 5 (A) is a mixture of CuQACDs and DPBF at 1.5 W / cm². 2 The ultraviolet absorption spectra of 808 nm laser irradiation for different times show that the absorption peak at 430 nm continuously decreases with increasing irradiation time. Figure 5 (B) provides CuQACDs, the standard substance methylene blue (MB), and the trapping agent DPBF at 1.5 W / cm². 2 Linear fitting plot of absorbance at 430 nm over time after 808 nm laser irradiation. In 10 min, the absorbance of DPBF at 430 nm decreased by 3.2%, MB by 39.7%, while CuQACDs showed a decrease of only 17.7%. The singlet oxygen yield of CuQACDs is approximately 0.23, indicating that its singlet oxygen generation capacity is slightly lower than that of methylene blue (0.52), which could reduce damage to normal tissues during wound treatment, making it suitable as a photodynamic therapy agent.

[0074] Further research was conducted on the types of ROS generated by CuQACDs under 808nm laser irradiation. ESR spectroscopy was used to test the types of ROS generated by CuQACDs under laser irradiation. Figure 6 (A) To select TEMP as a free radical scavenger, the generation of CuQACDs was detected. 1 The ESR spectrum obtained from O2 showed a triplet signal with a peak intensity ratio of 1:1:1, which is TEMPO (TEMP was...). 1 The characteristic peaks of the products after O2 oxidation indicate that CuQACDs have the ability to produce 1 The ability of O2. Figure 6 (B) To select DMPO as a free radical scavenger, the superoxide radicals (·O2) generated by CuQACDs were detected. - The ESR spectra obtained from DMPO and hydroxyl radicals (·OH) show a quartet with a peak intensity ratio of 1:2:2:1. - The characteristic peaks of the ·OH adduct indicate that CuQACDs have the ability to generate ·OH. In summary, CuQACDs possess the ability to simultaneously generate two ROS, demonstrating their potential as an excellent photosensitizer.

[0075] After exploring the extracellular reactive oxygen species (ROS) generation capacity of CuQACDs, the intracellular ROS generation capacity of CuQACDs was further evaluated. DCFH-DA was selected as a probe to detect ROS generation by CuCCDs within bacterial cells, and the fluorescence intensity of DCFH-DA after co-culturing with *Escherichia coli* and *Staphylococcus aureus* was measured using a fluorescence spectrophotometer. Figure 7 As shown in (A) and (B), after co-culturing Escherichia coli and Staphylococcus aureus with different concentrations of CuQACDs, the laser irradiation groups at 1.5 W / cm² showed... 2 After 10 minutes of 808 nm laser irradiation, the fluorescence intensity was significantly enhanced compared to the corresponding unirradiated group. Each unirradiated group also showed an increase in fluorescence intensity relative to the control group, presumably due to oxidative stress caused by co-culturing bacterial cells with CuQACDs, leading to increased intracellular ROS levels (Dubois-Deruy et al., 2020). However, in the control group, where only an equal amount of PBS was added for co-culturing with bacterial cells, the fluorescence intensity of the samples showed almost no change regardless of laser irradiation, indicating that almost no ROS was generated intracellularly. In summary, CuQACDs can significantly generate ROS within bacterial cells under 808 nm laser irradiation, demonstrating potential as a near-infrared photosensitizer for antibacterial therapy.

[0076] like Figure 8 and Figure 9As shown, when the CuQACDs concentration was 0 mg / mL, a large number of colonies appeared on the agar plates of both Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus, and the survival rates of the bacterial cells were similar before and after laser irradiation. With the increase of the CuQACDs concentration, the survival rates of the bacterial cells of each group without laser irradiation decreased in turn, and the laser irradiation groups had lower survival rates of the bacterial cells, indicating that CuQACDs had certain antibacterial properties, and after laser irradiation, the antibacterial performance of CuQACDs was greatly improved.

[0077] The above description of disclosed embodiments enables one skilled in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A carbon dot with photothermal and photodynamic dual phototherapy performance, characterized in that, The carbon dots are carbon dots with PDT and PTT synergistic antibacterial prepared by a one-step hydrothermal method; the carbon dots are prepared by taking quaternary ammonium salt as a carbon source and loading copper ions; and the carbon dots are CuQACDs. The quaternary ammonium salt is allyl trimethyl ammonium chloride, bisquid dimethyl ammonium chloride or bisalkyl dimethyl ammonium chloride.

2. The method for preparing carbon dots with photothermal and photodynamic dual phototherapy performance according to claim 1, characterized in that, The method specifically comprises the following steps: The copper salt and the quaternary ammonium salt are weighed and added to water for stirring and dissolving; then hydrothermal reaction is carried out, and after the reaction is completed, the reaction product is left to room temperature, filtered, purified by dialysis and freeze-dried to obtain the carbon dots with photothermal and photodynamic dual-light therapy performance. 3.The method for preparing carbon dots with photothermal and photodynamic dual phototherapy performance according to claim 2, characterized in that, The copper salt is copper chloride dihydrate, copper sulfate, copper carbonate or copper nitrate. The mass ratio of the copper salt to the quaternary ammonium salt is 1:5-3:

1. 4.The method for preparing carbon dots with photothermal and photodynamic dual phototherapy performance according to claim 2, characterized in that, The hydrothermal reaction temperature is 150-210 DEG C, and the hydrothermal reaction time is 3-8 h.

5. The carbon dots with photothermal and photodynamic dual-light therapy performance according to claim 1 or prepared by the method according to claim 2 are applied in antibacterial.

Images