Preparation and application of carbon quantum dots

Abstract

The invention discloses preparation and application of carbon quantum dots. The quantum dot is obtained by dissolving arginine, cobalt salt and organic acid in water, heating for reaction, taking supernatant, dialyzing and freeze-drying. The quantum dots can be used for preparing a hydrogel system, and the hydrogel system is obtained by compounding the cobalt-doped arginine carbon dots and ZIF-8 and then packaging the mixture and CaO2 in a double-crosslinking injectable hydrogel matrix. The method has a photothermal effect and multiple enzyme activity. In the early stage of infection, the weakly acidic microenvironment of the wound triggers CaO2 to be decomposed to generate H2O2, and carbon quantum dots are promoted to be released; under laser irradiation, the system synergistically generates local high heat, releases NO gas and catalyzes to generate hydroxyl radicals, so that photo-thermal / gas / chemical kinetics triple synergistic sterilization is realized. In a microenvironment at the later stage of inflammation, the enzyme activity of the system is converted into an anti-oxidation mode and cooperates with the release of tannic acid to regulate and control polarization of macrophages, so that the inflammation is effectively relieved. The invention provides an innovative integrated solution for the treatment of infectious wounds.

Description

Technical Field

[0001] This invention relates to an antibacterial gel material based on carbon quantum dots, and more particularly to the preparation of cobalt-doped arginine carbon dots for sequential treatment of infected wounds and their application in a microenvironment-responsive composite hydrogel system. Background Technology

[0002] The treatment of infected wounds is a significant clinical challenge. Due to multiple factors, including bacterial infection, persistent inflammatory response, and impaired tissue regeneration, the healing process of infected wounds is often delayed or interrupted. An ideal wound dressing should be able to dynamically respond to changes in the microenvironment during the healing process, providing precise, sequential intervention throughout the entire "antibacterial-anti-inflammatory-repair" process.

[0003] While treatment strategies for infected wounds have made some progress, significant limitations remain. For example, the overuse of antibiotics has led to increasingly serious bacterial resistance problems, necessitating the development of novel antibiotic-free antibacterial strategies. Photothermal therapy (PTT), as a physical antibacterial method, uses photothermal agents to generate localized high heat under near-infrared laser irradiation to destroy bacterial structures, providing a new approach to overcoming bacterial resistance. Among these, carbon-based materials (such as carbon quantum dots) show great potential in the PTT field due to their excellent biocompatibility and tunable photothermal conversion properties. Researchers are further enhancing their performance through methods such as elemental doping. For instance, iron-doped carbon quantum dots can achieve a synergistic effect between photothermal therapy and reactive oxygen species (ROS); by adjusting the elemental ratio, photothermal therapy of carbon dots in the near-infrared II region can also be achieved.

[0004] However, existing technologies still face the following core problems: limited functionality or insufficient temporal regulation, making it difficult to cover the entire healing cycle; passive response modes, unable to autonomously adjust treatment strategies according to changes in the microenvironment; and a lack of integrated solutions that organically combine highly effective antibacterial and chemokinetic therapy with subsequent anti-inflammatory and repair-promoting functions. These limitations severely restrict the efficient healing of infected wounds. Summary of the Invention

[0005] Objectives of this invention: The objective of this invention is to provide a method for preparing carbon quantum dots, solving the problem of how to prepare carbon quantum dots with antibacterial effects. A second objective is to propose an application of carbon quantum dots in the preparation of antibacterial hydrogel materials, solving the problem of how to prepare antibacterial hydrogel materials. A third objective is to propose an application of antibacterial hydrogel materials in the preparation of medical devices or dressings for treating bacterial infected wounds, solving the problem of how to prepare medical devices or dressings for treating bacterial infected wounds.

[0006] Technical solution: The present invention provides a method for preparing carbon quantum dots, comprising the following steps: dissolving arginine, cobalt salt and organic acid or their salt in water, heating and reacting, centrifuging to collect the supernatant, dialyzing and freeze-drying the supernatant to obtain Co-Arg-CDs.

[0007] Preferably, the organic acid includes at least one of citric acid, oxalic acid, formic acid, acetic acid, and propionic acid; the organic acid salt includes a sodium or potassium salt of the organic acid; and the cobalt salt includes at least one of cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt acetate.

[0008] Preferably, the mass ratio of arginine, organic acid or its salt and cobalt salt is 1:0.2-1:0.04-0.08; the heating reaction is carried out at 150-210℃ for 8-12 h.

[0009] The second aspect of this invention discloses the application of carbon quantum dots obtained by the above method in the preparation of antibacterial hydrogel materials.

[0010] Preferably, the method for preparing antibacterial hydrogel materials using the above-mentioned carbon quantum dots includes the following steps: (1) The carbon quantum dots are loaded onto a metal-organic framework material to obtain an intermediate; (2) Sodium oxidized alginate and carboxymethyl chitosan were added to a buffer solution and mixed to react, resulting in a double crosslinked gel; (3) Add the intermediate and CaO2 to the double crosslinked gel and mix well. Spray the PBS solution of tannic acid and mix well to obtain the antibacterial hydrogel material.

[0011] Preferably, in step (1), the method for loading the carbon quantum dots onto the metal-organic framework material is as follows: 2-Methylimidazolium is dissolved in an organic solvent to give a first solution; A second solution is obtained by dissolving zinc salt and carbon quantum dots in an organic solvent; The first solution and the second solution were mixed and stirred to react, yielding the first product. The first product was centrifuged to collect the precipitate, which was then washed and dried to obtain the intermediate.

[0012] Further, the organic solvent is a mixture of N,N-dimethylformamide and methanol in a volume ratio of 2-6:1; the zinc salt includes at least one of zinc nitrate, zinc sulfate, and zinc chloride; The ratio of 2-methylimidazole to organic solvent is 1-1.5 g: 10-30 mL; The ratio of zinc salt, carbon quantum dots, and organic solvent is 1-1.5 g : 0.3-0.7 g : 20-40 mL; The stirring reaction conditions are 400-1000 rpm for 10-60 min.

[0013] Preferably, in step (2), the method for preparing sodium alginate oxide is as follows: Sodium alginate was dispersed in an alcohol solvent to form a suspension. The suspension was mixed with an aqueous solution of NaIO4 and reacted at room temperature in the dark. Ethylene glycol was added to terminate the reaction. Subsequently, the precipitate was precipitated in an alcohol solvent. The precipitate was dialyzed and freeze-dried to obtain oxidized sodium alginate. The oxidation degree of sodium alginate is 80-90%, and the degree of carboxymethyl substitution of carboxymethyl chitosan is 0.5-1.2. Sodium alginate oxidase and carboxymethyl chitosan solution were mixed and the pH was adjusted to 7.0-7.4 with PBS buffer. The mixture was then stirred at a mass ratio of 1:1-1:1.5 at room temperature to initiate a Schiff base reaction and form a hydrogel. The reaction was carried out at room temperature for 2-4 hours.

[0014] The buffer solution in step (2) is selected from one of phosphate buffer, Tris buffer, and citrate buffer.

[0015] In some embodiments, the molar ratio of sodium alginate to NaIO4 is 1-1.5:1-1.5; the alcohol solvent includes at least one of methanol and ethanol.

[0016] Preferably, in step (3), the method for preparing CaO2 is as follows: Calcium chloride, ammonia, and polyethylene glycol were mixed and stirred. H2O2 was added, and the pH of the reaction system was adjusted to alkaline with NaOH. After the reaction was completed, the mixture was centrifuged and washed to obtain CaO2. In some embodiments, NaOH is used to adjust the pH of the reaction system to 11-12, the volume ratio of H2O2 to ammonia is 1:1, and the polyethylene glycol is PEG-200.

[0017] The mass ratio of intermediate to CaO2 is 0.05-0.2:150-250, and the mass fraction of tannic acid in the PBS solution of tannic acid is 2.5-5%.

[0018] In some embodiments, the PBS solution of tannic acid uses 1×PBS with a pH of 7.0-7.4 as the solvent.

[0019] The third aspect of this invention discloses the application of the antibacterial hydrogel material prepared by the above method in the preparation of medical devices or dressings for treating bacterial infected wounds.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The Co-Arg-CDs prepared in this invention possess photothermal effects and multiple enzyme activities, including peroxidase-like, superoxide dismutase-like, and catalase-like activities. In the early stages of infection, the weakly acidic microenvironment of the wound triggers the decomposition of CaO2 to produce H2O2, which in turn promotes the release of Co-Arg-CDs. Under 808 nm laser irradiation, the system synergistically generates localized high heat, releases nitric oxide gas, and catalyzes the generation of hydroxyl radicals, achieving a triple synergistic bactericidal effect through photothermal / gas / chemical kinetics. As the healing process progresses, in the late-stage inflammatory microenvironment, the system's enzyme activity shifts to an antioxidant mode to scavenge excess reactive oxygen species and, in conjunction with the release of TA, regulates macrophage polarization, effectively alleviating inflammation and promoting collagen deposition and angiogenesis.

[0021] This invention enables intelligent, time-sequential control of the entire "antibacterial-anti-inflammatory-repair" cycle of wounds, providing an innovative integrated solution for the treatment of infected wounds. Attached Figure Description

[0022] Figure 1 The images show the physicochemical characterization test results of Co-Arg-CDs and Co-Arg-CDs / ZIF-8 prepared in Example 1.

[0023] Figure 2 The image shows the photothermal performance test results of Co-Arg-CDs prepared in Example 1.

[0024] Figure 3 The image shows the POD / SOD / CAT enzyme activity test results of the Co-Arg-CDs prepared in Example 1.

[0025] Figure 4 The NO generation concentration of the Co-Arg-CDs prepared in Example 1.

[0026] Figure 5 Morphological and mechanical characterization of the HCC hydrogel prepared in Example 1.

[0027] Figure 6 The in vitro antibacterial, antioxidant and anti-inflammatory effects of the HCC hydrogel prepared in Example 1 were evaluated.

[0028] Figure 7 Schematic diagram of the wound closure process after treating Staphylococcus aureus-infected mouse wounds with PBS, OSA / CMCS, Co-Arg-CDs / ZIF-8@OSA / CMCS, HCC, and HCC + NIR hydrogel, respectively.

[0029] Figure 8 Schematic diagrams of the histomorphological appearance of wounds after treatment with PBS, OSA / CMCS, Co-Arg-CDs / ZIF-8@OSA / CMCS, HCC, and HCC + NIR hydrogel, respectively. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0031] Example 1: A method for preparing carbon quantum dots is as follows: Weigh 1 g L-Arg and 0.40 g sodium citrate and dissolve them in 20 mL of ultrapure water. Then add 0.05 g Co(NO3)2·6H2O, sonicate for 15 min, and transfer the mixture to a 50 mL high-temperature and high-pressure reactor. React at 180 °C for 8 h. After the reaction, centrifuge at 8000 rpm for 30 min, collect the supernatant, filter the supernatant through a 0.22 μm filter membrane, and then dialyze it against ultrapure water in a 1000 Da dialysis bag for three days. Freeze-dry the dialyzed supernatant to obtain carbon quantum dots Co-Arg-CDs.

[0032] The prepared Co-Arg-CDs were used to prepare antibacterial hydrogel materials, as follows: (1) An organic solvent was prepared by mixing N,N-dimethylformamide (DMF) and methanol at a volume ratio of 4:1. 1.16 g of 2-methylimidazole was dissolved in 20 mL of this organic solvent to obtain a first solution. 1.069 g of Zn(NO3)2·6H2O and 0.552 g of Co-Arg-CDs were dissolved in 30 mL of this organic solvent to obtain a second solution. Subsequently, the first and second solutions were mixed and stirred at 700 rpm for 30 min. The reaction product was centrifuged to collect the precipitate, which was washed three times with ethanol. The precipitate was then dried in a vacuum oven to obtain Co-Arg-CDs / ZIF-8.

[0033] (2) 10 g of sodium alginate (SA) was dispersed in 100 mL of anhydrous ethanol and stirred to form a homogeneous suspension. Then, an equimolar amount of NaIO4 was dissolved in 100 mL of pure water and stirred thoroughly at 500 rpm to obtain an aqueous solution of NaIO4. The SA suspension and the NaIO4 aqueous solution were mixed and reacted at room temperature in the dark for 6 h. After the reaction was complete, an equimolar amount of ethylene glycol was added, and stirring was continued for 30 min to terminate the reaction. The reaction product was then poured into anhydrous ethanol and allowed to settle for precipitation. After 12 h, the supernatant was discarded, and the lower precipitate was placed in a dialysis bag (MWCO 3500) and dialyzed in ultrapure water for 3 days. Finally, the dialysate was collected and freeze-dried to obtain oxidized sodium alginate (OSA) with an oxidation degree of 80-90%.

[0034] (3) Dissolve 1 g of CaCl2 in 10 mL of deionized water. Then, mix the resulting CaCl2 aqueous solution with 5 mL of ammonia water (v / v) with a concentration between 25% and 28% and 50 mL of polyethylene glycol-200 in a flask. Stir at 500 rpm for 15 min at room temperature, slowly add 5 mL of 30% H2O2 (v / v) aqueous solution to the mixture, and continue stirring for 120 min. To optimize the reaction conditions, add an appropriate amount of NaOH solution to the mixture to adjust the pH of the reaction system to 11.5. After the reaction is complete, centrifuge the resulting turbid liquid at 11000 rpm for 600 s using a high-speed centrifuge to achieve solid-liquid separation. After centrifugation, wash the precipitate 5 times with ethanol to obtain CaO2. Store the CaO2 in an ethanol solution at 4℃ to maintain its stability. (4) 0.1 g of oxidized sodium alginate (OSA) and 0.1 g of carboxymethyl chitosan (CMCS) with a degree of carboxymethyl substitution of 0.85 were dissolved in phosphate buffered saline (PBS) at pH 7.4 and reacted at room temperature for 3 h to form a basic hydrogel (OSA / CMCS) through a Schiff base reaction. Subsequently, calcium peroxide (CaO2) particles and Co-Arg-CDs / ZIF-8 nanocomposite materials were incorporated into the basic hydrogel, so that the final mass concentrations of the two in the gel were 0.2 g / mL and 100 μg / mL, respectively. After standing for 2 h, a Co-Arg-CDs / ZIF-8 / CaO2@OSA / CMCS composite hydrogel was obtained. Finally, 1 mL of 2.5% tannic acid (TA) aqueous solution was uniformly sprayed on the surface of the composite hydrogel. Through secondary crosslinking of TA and the polymer network, the final double-crosslinked injectable hydrogel was obtained, denoted as HCC hydrogel.

[0035] The Co-Arg-CDs and Co-Arg-CDs / ZIF-8 prepared in this embodiment were subjected to physicochemical characterization tests, and the results are as follows: Figure 1 As shown, Figure 1 Figure a shows a TEM image of Co-Arg-CDs, and the inset shows the lattice spacing of Co-Arg-CDs. It can be seen that the prepared Co-Arg-CDs are generally spherical, uniformly dispersed, and have a narrow size distribution. High-resolution TEM measured its lattice spacing to be 0.21 nm, corresponding to the (0 0 1) crystal phase of graphite.

[0036] 5.7 mmol L-Arg and 2.9 mmol ethylenediamine were dissolved in 10 mL of ultrapure water and transferred to a hydrothermal reactor. The reaction temperature was 180 °C, and the reaction was carried out for 8 h. After cooling the reactants to room temperature, they were removed and dialyzed with ultrapure water in a 1000 Da dialysis bag. The purified, metal-free Arg-CDs were then freeze-dried and used as a control for subsequent reactions.

[0037] Figure 1 In Figure b, the average size of Arg-CDs is approximately 2.5 nm, while in Figure c, the average size of Co-Arg-CDs is approximately 2.75 nm. Compared to undoped Arg-CDs, their size is increased, which may be due to the introduction of metal ions, leading to an increase in carbon dot size.

[0038] Figure 1 Figure d shows the infrared spectra of Co-Arg-CDs and Co-Arg-CDs / ZIF-8. The infrared spectra indicate that Co-Arg-CDs successfully retained the characteristic functional groups such as the guanidinium group of the precursor L-Arg, especially in the 3200-3300 cm⁻¹ region. 1 The NH stretching vibration peak at this location broadened significantly, which is attributed to Co. 2+ The coordination with NH2 leads to a decrease in the electron cloud density of the NH bond and an alteration in the hydrogen bond environment. Furthermore, at 1640 cm⁻¹... 1 The C=N stretching vibration peak at that location has shifted to 1668 cm⁻¹. 1 This may be Co 2+ This affected the electron cloud density, thereby altering the vibrational modes. These changes collectively confirm the influence of Co. 2+ The coordination structure with the amino groups on the surface of Arg-CDs verified the successful synthesis of Co-Arg-CDs.

[0039] In the Co-Arg-CDs / ZIF-8 composite system, the Zn-N characteristic vibrational peak of the ZIF-8 framework (pure phase located at 420 cm⁻¹) 1 The blue color shifted to 437 cm. 1 This indicates that Co 2+ Partially replaces Zn 2+ A Zn / Co mixed coordination node was formed, and the shorter bond length of the Co-N bond (compared to Zn-N) led to an increase in vibrational frequency. Meanwhile, the 1568 cm⁻¹ in ZIF-8... 1 The C=N stretching vibration peak at that location shifted (to 1582 cm). 1 This may be due to the surface functional groups of Co-Arg-CDs interacting with the Zn of ZIF-8. 2+ Interaction occurs, or Co 2+ The doping induces a redistribution of the electron cloud density in the imidazole ring. These results reveal a synergistic coordination effect between Co-Arg-CDs and ZIF-8, providing a structural basis for the design of composite materials.

[0040] Figure 1 Figure e shows the XRD patterns of Co-Arg-CDs and Co-Arg-CDs / ZIF-8. It is evident that the XRD pattern of Co-Arg-CDs exhibits the typical amorphous structure of carbon dots. Even after Co doping, the crystal structure of Co-Arg-CDs remains amorphous. Furthermore, the XRD pattern of Co-Arg-CDs / ZIF-8 is highly consistent with the standard pattern of ZIF-8 and shows obvious diffraction peaks, indicating that Co-Arg-CDs / ZIF-8 has a high degree of crystallinity.

[0041] The photothermal properties of Co-Arg-CDs were tested, and the results are as follows: Figure 2 As shown, by Figure 2 Figures a and b show that the photothermal performance of Co-Arg-CDs increases with increasing concentration, exhibiting a concentration-dependent effect. At an 808 nm exciter with this power, Co-Arg-CDs at concentrations of 500 μg / mL and above can reach a maximum temperature of over 40°C within 10 minutes, sufficient to kill bacteria. Meanwhile, the temperature of the control group (H2O) remained almost unchanged. Subsequently, 500 μg / mL Co-Arg-CDs were irradiated for 10 minutes at different power densities to investigate its photothermal performance. The results are as follows... Figure 2 As shown in Figure c, the photothermal performance increases with increasing power density. To further investigate the stability of the photothermal performance of Co-Arg-CDs, 500 μg / mL Co-Arg-CDs were exposed to an 808 nm laser emitter (5 W / cm²). 2 Five cycles of photothermal measurements were performed, and the results are as follows: Figure 2 As shown in Figure d, the maximum temperature of the samples remained almost unchanged within five thermal cycles, which fully demonstrates the good photothermal stability of Co-Arg-CDs. Based on the photothermal conversion efficiency formula, the photothermal conversion efficiency of Co-Arg-CDs can be calculated to be 37.85%, exhibiting high energy conversion capability.

[0042] The POD / SOD / CAT-like enzyme activity of the Co-Arg-CDs prepared in this embodiment was detected, and the results are as follows: Figure 3 As shown. Figure 3Figure a shows the rate of O2 generation from Co-Arg-CDs at different concentrations with a fixed H2O2 concentration. Figure 3 Figure b shows the rate of O2 generation from different concentrations of H2O2 under a fixed Co-Arg-CDs concentration. It can be seen that the POD-like enzyme activity of Co-Arg-CDs follows the Michaelis-Menten equation; with TMB and H2O2 as substrates, the activity of Co-Arg-CDs... K m The values ​​are 0.0267 and 0.0487 mM, respectively. The corresponding values ​​are... V max The values ​​were 0.3953 and 0.0487 μM / s, respectively. K m The values ​​are respectively compared to natural HRP (TMB: K m =0.434 mM; H2O2: K m = 3.7 mM) decreased by 16-fold and 76-fold, indicating that Co-Arg-CDs have a stronger substrate binding capacity. Although V max The value is lower than HRP (HRP to TMB). V max (Approximately 10 μM / s), but Co-Arg-CDs still maintain a high level of specific catalysis for TMB. Figure 3 Figures e and f show the changes in dissolved oxygen with the concentrations of H₂O₂ and Co-Arg-CDs. These results indicate a significant substrate- and enzyme-concentration-dependent change in oxygen content. Further analysis using Michaelis-Menten kinetics (e.g., ...) was performed... Figure 3 As shown in Figure g), the CAT-like enzyme activity of Co-Arg-CDs conforms to the Michaelis-Menten equation, and its Michaelis-Menten constant is... K m The maximum initial reaction rate is 0.173 M. V max It was 2.40 mg / L / min. Compared to natural CAT ( K m Compared to (25 mM), Co-Arg-CDs exhibit superior substrate affinity ( K m These results (more than 14 times lower) indicate that Co-Arg-CDs possess good CAT-like enzyme activity and can efficiently catalyze the decomposition of H2O2. Figure 3As shown in Figure h, the SOD-like enzyme activity of Co-Arg-CDs significantly increases with increasing concentration, indicating that it possesses good SOD-like enzyme activity. Co-Arg-CDs can effectively catalyze... O2 This process converts the free radicals into H2O2 and O2, thereby scavenging free radicals and alleviating oxidative stress. In the later stages of the wound microenvironment, a large number of inflammatory factors and free radicals exist. Co-Arg-CDs, through their SOD-like enzyme activity, can effectively scavenge H2O2. - It reduces inflammation, thereby promoting wound healing.

[0043] Further investigation of the NO release kinetics of Co-Arg-CDs yielded the following results: Figure 4 As shown. By Figure 4 It is evident that the NO formation concentration of Co-Arg-CDs is approximately twice that of Arg-CDs. This is likely because metal doping alters the surface charge distribution, thereby affecting the charge distribution at the guanidinium group and thus increasing NO formation efficiency. Furthermore, Co doping may also enhance the electron transport capacity of the material, promoting the oxidation reaction of the guanidinium group in L-Arg and further increasing NO release.

[0044] The morphology and mechanical properties of the HCC hydrogel were characterized, and the results are as follows: Figure 5 As shown, by Figure 5 As can be seen, HCC hydrogels exhibit excellent microstructure and mechanical properties. SEM images show that both OSA / CMCS and HCC hydrogels possess a three-dimensional porous network structure (e.g., Figure 5 As shown in Figures a and b), the synthesized HCC hydrogel has a more compact cross-linked structure compared to the OSA / CMSC hydrogel. This structural optimization mainly stems from the synergistic effect of the dual cross-linked network and the Ca2+ produced by CaO2 decomposition. 2+ Additional cross-linking and the physical reinforcement effect of Co-Arg-CDs / ZIF-8 nanoparticles were investigated. The general mechanical properties of the hydrogels were explored using a rheometer. The results showed that the G′ of all hydrogels was higher than their G′′, indicating that the experimental group of hydrogels formed a stable elastic network (e.g., Figure 5 (As shown in Figure c). The introduction of CaO2 and Co-Arg-CDs / ZIF-8 significantly improved the mechanical properties of the hydrogel, which may be due to these components enhancing the crosslinking density and intermolecular interactions of the hydrogel. Linear viscoelastic region testing showed that the hydrogel possessed excellent toughness, with a fracture point exceeding 100%, further confirming its good mechanical stability (e.g., ...). Figure 5 (See Figure d in the middle). To further evaluate the mechanical properties of the HCC hydrogel, its typical tensile properties were tested. Stress-strain curves (as shown in Figure d) Figure 5As shown in Figure e, the hydrogel exhibits high tensile strength and good deformation capacity, indicating its ability to withstand significant external forces without fracture. Furthermore, cyclic strains of 1% and 200% were applied to the hydrogel to investigate its self-healing properties. Figure 5 As shown in Figure f, the hydrogel can recover to its initial modulus even after its structural network is completely destroyed, indicating its excellent self-healing ability. This self-healing property is mainly attributed to the reversibility of the Schiff base bonds in the hydrogel, which allows it to reform the network structure after the external stress is removed.

[0045] Following the same method described above, only Co-Arg-CDs / ZIF-8 was added to OSA / CMCS without adding CaO2 to obtain Co-Arg-CDs / ZIF-8@OSA / CMCS hydrogel, which was used for subsequent experiments.

[0046] Further evaluation of the in vitro antibacterial, antioxidant, and anti-inflammatory properties of the HCC hydrogel yielded the following results: Figure 6 As shown, the PBS group, OSA / CMCS group, Co-Arg-CDs / ZIF-8@OSA / CMCS group, HCC hydrogel, and HCC hydrogel with external 808 nm near-infrared light (1.5 W / cm²) were compared. 2 Exposure (HCC+NIR) was used to reveal the impact on antibacterial properties, by Figure 6 It can be seen that the first three groups S. aureus and E. coli The bacterial survival rate was higher in the first group and higher in the second group. S. aureus and E. coli The survival rate of bacteria was significantly reduced, and bacterial death occurred. The HCC + NIR group showed significantly reduced bacterial survival. S. aureus and E. coli The kill rates reached 99.92±0.13% and 99.76±0.28%, respectively. This is because the addition of laser irradiation achieved multi-component synergistic antibacterial activity, thereby achieving complete elimination of bacteria. The antioxidant performance of the hydrogel was evaluated using a DPPH total antioxidant capacity kit. The results are as follows: Figure 6 As shown in Figure e, compared with the OSA / CMCS hydrogel, the Co-Arg-CDs / ZIF-8@OSA / CMCS composite hydrogel exhibited a significantly enhanced free radical scavenging ability, reaching 65%. Further research revealed that after the addition of tannic acid (TA), HCC showed an antioxidant capacity of 87%, indicating that the synthesized composite hydrogel possesses excellent free radical scavenging ability in vitro. In addition, the anti-inflammatory ability of the hydrogel was evaluated (e.g., Figure 6 As shown in Figure f, this result indicates that HCC hydrogel exhibits the best anti-inflammatory properties, with an inflammation inhibition rate of up to 77%.

[0047] In mice infected with Staphylococcus aureus, wounds were treated with PBS, OSA / CMCS, Co-Arg-CDs / ZIF-8@OSA / CMCS, HCC, and HCC + NIR hydrogels, respectively. The wound closure process was observed after treatment. Mice were randomly divided into five groups: PBS group, OSA / CMCS group, Co-Arg-CDs / ZIF-8@OSA / CMCS group, HCC group, and HCC + NIR group. A circular wound with a diameter of 8 mm was created on the back of each mouse, and inoculated with... S. aureus To construct wound infection models (such as) Figure 7 (As shown in Figure a). Subsequently, different types of hydrogels were applied to the wounds of mice to evaluate their therapeutic effects. Images of wound changes were taken on days 0, 2, 5, 7, and 10 during the wound healing process (e.g., [Figure a is missing]). Figure 7 As shown in Figure b), the surface area of ​​the mouse wound was quantitatively analyzed (e.g., Figure 7 (As shown in Figure c). The results showed that the healing effect of the HCC + NIR group was significantly better than that of other groups, with a wound healing rate of 98.86±0.63%, almost complete recovery. These results indicate that HCC + NIR has a significant promoting effect on wound healing. Throughout the experiment, the weight of the mice was recorded (e.g., [Figure c]). Figure 7 As shown in Figure d), all mice were growing well, and their body weight showed an increasing trend after 14 days, demonstrating the biocompatibility of the material.

[0048] After 14 days of treatment, skin tissue and major organs from the wound site were collected for histological analysis. For example... Figure 8 As shown, the HCC+NIR group exhibited superior wound healing. The formation of structures such as hair follicles was observed in the healing area, further confirming the significant repair effect of the synergistic strategy combined with the wound infection model. Simultaneously, collagen accumulation in the HCC+NIR group showed a gradually increasing trend. Combined with the section results, this composite system can promote collagen deposition and skin tissue remodeling.

[0049] Example 2: A method for preparing carbon quantum dots is as follows: Weigh 1 g L-Arg and 0.20 g sodium citrate and dissolve them in 20 mL ultrapure water. Then add 0.04 g Co(NO3)2·6H2O, sonicate for 30 min, and transfer the mixture to a 50 mL high-temperature and high-pressure reactor. React at 150 °C for 12 h. After the reaction, centrifuge at 10,000 rpm for 30 min and collect the supernatant. Filter the supernatant through a 0.22 μm filter membrane, and then dialyze it in deionized water for three days in a 1000 Da dialysis bag. Freeze-dry the dialyzed supernatant to obtain carbon quantum dots Co-Arg-CDs.

[0050] The prepared Co-Arg-CDs were used to prepare antibacterial hydrogel materials, as follows: (1) An organic solvent was prepared by mixing N,N-dimethylformamide (DMF) and methanol at a volume ratio of 2:1. 1 g of 2-methylimidazole was dissolved in 10 mL of this organic solvent to obtain the first solution. 1 g of zinc sulfate and 0.3 g of Co-Arg-CDs were dissolved in 20 mL of this organic solvent to obtain the second solution. Subsequently, the first and second solutions were mixed and stirred at 400 rpm for 60 min. The reaction product was centrifuged to collect the precipitate, which was washed three times with ethanol. The precipitate was then dried in a vacuum oven to obtain Co-Arg-CDs / ZIF-8.

[0051] (2) 15 g of sodium alginate (SA) was dispersed in 100 mL of anhydrous ethanol and stirred to form a homogeneous suspension. Then, 0.7 times the amount of SA was dissolved in 100 mL of pure water and stirred thoroughly at 500 rpm to obtain an aqueous solution of NaIO4. The SA suspension and the NaIO4 aqueous solution were mixed and reacted at room temperature in the dark for 4 h. After the reaction was completed, ethylene glycol of the same amount as NaIO4 was added and stirred for another 30 min to terminate the reaction. Then, the reaction product was poured into anhydrous ethanol and allowed to stand for precipitation. After 12 h, the supernatant was discarded, and the lower precipitate was placed in a dialysis bag (MWCO 3500) and dialyzed in deionized water for 3 days. Finally, the dialysate was collected and freeze-dried to obtain oxidized sodium alginate (OSA) with an oxidation degree of 80-90%.

[0052] (3) Dissolve 1.5 g CaCl2 in 10 mL of deionized water. Then, mix the resulting CaCl2 aqueous solution with 5 mL of ammonia water (v / v) with a concentration between 25% and 28% and 50 mL of polyethylene glycol-200 in a flask. Stir at 500 rpm for 15 min at room temperature, then slowly add 5 mL of 30% H2O2 (v / v) aqueous solution to the mixture and continue stirring for 120 min. To optimize the reaction conditions, add an appropriate amount of NaOH solution to the mixture to adjust the pH of the reaction system to 11. After the reaction is complete, centrifuge the resulting turbid liquid at 11000 rpm for 600 s using a high-speed centrifuge to achieve solid-liquid separation. After centrifugation, wash the precipitate 5 times with ethanol to obtain CaO2. Store the CaO2 in an ethanol solution at 4℃ to maintain its stability.

[0053] (4) 0.1 g OSA and 0.15 g CMCS with a carboxymethyl substitution degree of 0.5 were dissolved in 1×PBS at pH 7.4 and reacted at room temperature for 2 h to form a basic hydrogel through a Schiff base reaction. Subsequently, CaO2 particles and Co-Arg-CDs / ZIF-8 nanocomposite materials were incorporated into the gel, resulting in final mass concentrations of 0.15 g / mL and 50 μg / mL, respectively. After standing for 2 hours, a Co-Arg-CDs / ZIF-8 / CaO2@OSA / CMCS composite hydrogel was obtained. Finally, 1 mL of 2.5% TA-PBS solution was uniformly sprayed onto the surface of the composite hydrogel. Through secondary crosslinking of TA with the polymer network, the final double-crosslinked injectable hydrogel, denoted as HCC hydrogel, was obtained.

[0054] Example 3: A method for preparing carbon quantum dots is as follows: 1 g L-Arg and 1 g sodium citrate were weighed and dissolved in 20 mL of ultrapure water. Then, 0.08 g cobalt sulfate was added, and the mixture was sonicated for 45 min. The solution was then transferred to a 50 mL high-temperature and high-pressure reactor and reacted at 210 °C for 8 h. After the reaction, the supernatant was collected by centrifugation at 5000 rpm for 45 min and filtered through a 0.22 μm filter membrane. The supernatant was then dialyzed against deionized water in a 1000 Da dialysis bag for three days. The supernatant was then lyophilized to obtain carbon quantum dots Co-Arg-CDs.

[0055] The prepared Co-Arg-CDs were used to prepare antibacterial hydrogel materials, as follows: (1) An organic solvent was prepared by mixing N,N-dimethylformamide (DMF) and methanol at a volume ratio of 6:1. 1.5 g of 2-methylimidazole was dissolved in 30 mL of this organic solvent to obtain a first solution. 1.5 g of zinc chloride and 0.7 g of Co-Arg-CDs were dissolved in 40 mL of this organic solvent to obtain a second solution. Subsequently, the first and second solutions were mixed and stirred at 1000 rpm for 10 min. The reaction product was centrifuged to collect the precipitate, which was washed three times with ethanol. The precipitate was then dried in a vacuum oven to obtain Co-Arg-CDs / ZIF-8.

[0056] (2) Disperse 8 g of sodium alginate (SA) in 100 mL of anhydrous ethanol and stir to form a homogeneous suspension. Then, dissolve 1.5 times the amount of SA in NaIO4 in 100 mL of pure water and stir thoroughly at 500 rpm to obtain an aqueous solution of NaIO4. Mix the SA suspension and the NaIO4 aqueous solution and react at room temperature in the dark for 6 h. After the reaction is complete, add an equal amount of ethylene glycol to NaIO4 and continue stirring for 30 min to terminate the reaction. Then, pour the reaction product into anhydrous ethanol and let it stand to precipitate. After 12 h, discard the supernatant and place the lower precipitate in a dialysis bag (MWCO 3500) and dialyze it in deionized water for 3 days. Finally, collect the dialysate and freeze-dry it to obtain oxidized sodium alginate (OSA) with an oxidation degree of 80-90%.

[0057] (3) Dissolve 0.5 g CaCl2 in 10 mL of deionized water. Then, mix the resulting CaCl2 aqueous solution with 5 mL of ammonia water (v / v) with a concentration between 25% and 28% and 50 mL of polyethylene glycol-200 in a flask. Stir at 500 rpm for 15 min at room temperature, slowly add 5 mL of 30% H2O2 (v / v) aqueous solution to the mixture, and continue stirring for 120 min. To optimize the reaction conditions, add an appropriate amount of NaOH solution to the mixture to adjust the pH of the reaction system to 12. After the reaction is complete, centrifuge the resulting turbid liquid at 11000 rpm for 600 s using a high-speed centrifuge to achieve solid-liquid separation. After centrifugation, wash the precipitate 5 times with ethanol to obtain CaO2. Store the CaO2 in an ethanol solution at 4℃ to maintain its stability.

[0058] (4) 0.1 g OSA and 0.13 g CMCS with a carboxymethyl substitution degree of 1.2 were dissolved in PBS at pH 7.4 and reacted at room temperature for 4 h to form a basic hydrogel through Schiff base reaction. Subsequently, CaO2 particles and Co-Arg-CDs / ZIF-8 nanocomposite materials were incorporated into the gel, so that the final mass concentrations of the two in the gel were 0.25 g / mL and 200 μg / mL, respectively. After standing for 2 h, Co-Arg-CDs / ZIF-8 / CaO2@OSA / CMCS composite hydrogel was obtained. Finally, 1 mL of 2.5% TA aqueous solution was uniformly sprayed on the surface of the composite hydrogel. Through secondary crosslinking of TA and polymer network, the final double crosslinked injectable hydrogel, abbreviated as HCC hydrogel, was obtained.

[0059] Testing showed that the properties of the HCC hydrogels prepared in Examples 2 and 3 were similar to those in Example 1.

Claims

1. A method for preparing carbon quantum dots, characterized in that, The process includes the following steps: dissolving arginine, cobalt salt, and organic acid or their salt in water, heating the reaction, centrifuging to collect the supernatant, dialyzing the supernatant and lyophilizing it to obtain Co-Arg-CDs.

2. The method for preparing carbon quantum dots according to claim 1, characterized in that, The organic acid includes at least one of citric acid, oxalic acid, formic acid, acetic acid, and propionic acid, and the cobalt salt includes at least one of cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt acetate.

3. The method for preparing carbon quantum dots according to claim 1, characterized in that, The mass ratio of arginine, organic acid or its salt and cobalt salt is 1:0.2-1:0.04-0.08; the heating reaction is carried out at 150-210℃ for 8-12 h.

4. The application of carbon quantum dots prepared by the method according to any one of claims 1-3 in the preparation of antibacterial hydrogel materials.

5. The application according to claim 4, characterized in that, Includes the following steps: (1) The carbon quantum dots are loaded onto a metal-organic framework material to obtain an intermediate; (2) Sodium oxidized alginate and carboxymethyl chitosan were added to a buffer solution and mixed to react, resulting in a double crosslinked gel; (3) Add the intermediate and CaO2 to the double crosslinked gel and mix well. Spray the PBS solution of tannic acid and mix well to obtain a multifunctional hydrogel material.

6. The application according to claim 5, characterized in that, In step (1), the method for loading the carbon quantum dots onto the metal-organic framework material is as follows: 2-Methylimidazolium is dissolved in an organic solvent to give a first solution; A second solution is obtained by dissolving zinc salt and carbon quantum dots in an organic solvent; The first solution and the second solution were mixed and stirred to react, yielding the first product. The first product was centrifuged to collect the precipitate, which was then washed and dried to obtain the intermediate.

7. The application according to claim 6, characterized in that, The organic solvent is a mixture of N,N-dimethylformamide and methanol in a volume ratio of 2-6:1; the zinc salt includes at least one of zinc nitrate, zinc sulfate, and zinc chloride; The ratio of 2-methylimidazole to organic solvent is 1-1.5 g : 10-30 mL; The ratio of zinc salt, carbon quantum dots, and organic solvent is 1-1.5 g : 0.3-0.7 g : 20-40 mL; The stirring reaction conditions are 400-1000 rpm for 10-60 min.

8. The application according to claim 5, characterized in that, In step (2), the method for preparing oxidized sodium alginate is as follows: Sodium alginate was dispersed in an alcohol solvent to form a suspension. The suspension was mixed with an aqueous solution of NaIO4 and reacted at room temperature in the dark. Ethylene glycol was added to terminate the reaction. Subsequently, the precipitate was precipitated in an alcohol solvent. The precipitate was dialyzed and freeze-dried to obtain oxidized sodium alginate. The oxidation degree of sodium alginate is 80-90%, and the degree of carboxymethyl substitution of carboxymethyl chitosan is 0.5-1.

2. The mass ratio of oxidized sodium alginate to carboxymethyl chitosan was 1:1-1.5; the reaction conditions were 2-4 h at room temperature.

9. The application according to claim 5, characterized in that, In step (3), the method for preparing CaO2 is as follows: Calcium chloride, ammonia, and polyethylene glycol were mixed and stirred. H2O2 was added, and the pH of the reaction system was adjusted to alkaline with NaOH. After the reaction was completed, the mixture was centrifuged and washed to obtain CaO2. The mass ratio of intermediate to CaO2 is 0.05-0.2:150-250, and the mass fraction of tannic acid in the PBS solution of tannic acid is 2.5-5%.

10. The use of the antibacterial hydrogel material prepared according to any one of claims 4-9 in the preparation of medical devices or dressings for treating bacterial infected wounds.

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