Curcumin-carbon quantum dot composite nanomaterial as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of curcumin, and particularly relates to a curcumin-carbon quantum dot composite nanomaterial as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing an aqueous dispersion of carbon quantum dots and an ethanol solution of curcumin, and loading to obtain the curcumin-carbon quantum dot composite nanomaterial. The curcumin-carbon quantum dot composite nanomaterial prepared by the invention has excellent water solubility, dispersibility, stability, bioavailability and antibacterial property.

Description

Technical Field

[0001] This invention belongs to the field of curcumin technology, specifically relating to a curcumin-carbon quantum dot composite nanomaterial, its preparation method, and its application. Background Technology

[0002] Curcumin (Cur) is derived from the ginger plant turmeric (Curcuma longa). Curcuma longa L. Curcumin, a polyphenolic compound extracted from [unspecified source], has attracted widespread attention due to its unique biological activities. In recent years, studies have shown that curcumin has significant effects in antibacterial and antioxidant properties, leading to its increasingly widespread application in the food industry. Curcumin is a diketone compound with a strong yellow color; its molecular structure contains two aromatic rings and an α,β-unsaturated carbonyl group. It not only imparts an appealing color to food but also exhibits rich biological activities, including anti-inflammatory, anti-tumor, and lipid-lowering effects.

[0003] As people become more health-conscious, the demand for natural additives is increasing, leading to a greater use of curcumin in food processing to improve food safety and extend shelf life. Due to its vibrant color, curcumin is also widely used as a natural coloring agent. Compared to synthetic colorants, natural colorants are more favored by consumers because they are considered safer and non-toxic.

[0004] Curcumin's low water solubility, heat sensitivity, and light instability lead to poor system stability and bioavailability, severely limiting its application in functional foods and pharmaceuticals. To overcome these limitations, developing novel carriers with high solubility and good sustained-release effects is crucial for advancing curcumin-based food applications. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a curcumin-carbon quantum dot composite nanomaterial, its preparation method and application. The curcumin-carbon quantum dot composite nanomaterial prepared by this invention has excellent water solubility, dispersibility, stability, bioavailability and antibacterial properties.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing curcumin-carbon quantum dot composite nanomaterials, comprising the following steps: A mixture of an aqueous dispersion of carbon quantum dots and an ethanol solution of curcumin was used for loading to obtain curcumin-carbon quantum dot composite nanomaterials.

[0007] Preferably, the concentration of curcumin in the ethanol solution of curcumin is 0.5~1 mg / mL; the concentration of carbon quantum dots in the aqueous dispersion of carbon quantum dots is the same as the concentration of curcumin in the ethanol solution of curcumin.

[0008] Preferably, the volume ratio of the aqueous dispersion of carbon quantum dots to the ethanol solution of curcumin is 1 to 3:1.

[0009] Preferably, the method for preparing the carbon quantum dots includes the following steps: A carbon source, an amino compound, and water are mixed and then stirred and sonicated sequentially. The resulting mixture undergoes a hydrothermal reaction to obtain carbon quantum dots.

[0010] Preferably, the carbon source includes one or more of sodium citrate, citric acid, ascorbic acid, and chitosan.

[0011] Preferably, the amino compound includes amino acids and / or amine compounds; the amino acid includes one or more of L-aspartic acid, lysine, and cysteine; the amine compound includes ethylenediamine and / or urea.

[0012] Preferably, the mass ratio of the carbon source to the amino compound is 2~4:1~2.

[0013] Preferably, the hydrothermal reaction is carried out at a temperature of 160-200°C for 6-8 hours.

[0014] The present invention also provides a curcumin-carbon quantum dot composite nanomaterial prepared by the preparation method described above. The curcumin-carbon quantum dot composite nanomaterial is a near-spherical nanoparticle comprising curcumin and carbon quantum dots. The curcumin is connected and embedded in the carbon quantum dots through hydrogen bonds.

[0015] This invention also provides the application of the curcumin-carbon quantum dot composite nanomaterials described in the above technical solution in the preparation of antibacterial materials.

[0016] This invention provides a method for preparing curcumin-carbon quantum dot composite nanomaterials, comprising the following steps: mixing an aqueous dispersion of carbon quantum dots and an ethanol solution of curcumin, and loading the mixture to obtain curcumin-carbon quantum dot composite nanomaterials.

[0017] This invention employs an ethanol encapsulation method to load curcumin onto the surface of carbon quantum dots via hydrophobic interactions, π-π stacking, and hydrogen bonding, successfully preparing curcumin-carbon quantum dot composite nanomaterials. This method is simple to operate, has a mild reaction profile, and exhibits good reproducibility and stability. The curcumin-carbon quantum dot composite has a curcumin loading rate of approximately 2.80 wt%. The carbon quantum dots impart water solubility and dispersibility to the composite nanomaterial through their hydrophilic shell and surface charge, and their π-π stacking structure fixes and protects curcumin molecules, resulting in superior water solubility, dispersibility, and stability, thus solving the problem of curcumin's poor water solubility. Simultaneously, the carbon quantum dots guide the orderly self-assembly of curcumin molecules on their surface through directional π-π stacking and other intermolecular forces, forming thermodynamically more stable and structurally finer composite nanocrystals, thereby improving the dispersibility and bioavailability of curcumin. Furthermore, carbon quantum dots can act as photosensitizers, generating reactive oxygen species under light conditions to disrupt bacterial cell structure. Curcumin molecules are stably loaded onto the carbon dot surface through π-π stacking and hydrogen bonding, allowing for controlled release within the bacterial microenvironment. This allows them to directly act on the cell membrane and metabolic system, working together to exert a highly efficient bactericidal effect and exhibit significantly enhanced antibacterial properties. Experiments show that the composite nanomaterials have a significant concentration-dependent bactericidal effect against Staphylococcus aureus, achieving highly efficient sterilization even at relatively low concentrations. This composite nanomaterial provides a new approach for developing natural, efficient, and stable food-grade antibacterial agents. Attached Figure Description

[0018] Figure 1 Solubility analysis charts of curcumin (A), carbon quantum dots (B), curcumin-carbon quantum dots (C), and total (D) aqueous solutions at different concentrations (0.01~1 mg / mL); Figure 2 Stability analysis diagrams of aqueous solutions of curcumin (A), carbon quantum dots (B), and curcumin-carbon quantum dots (C); Figure 3 XRD spectra of curcumin, carbon quantum dots, and curcumin-carbon quantum dots; Figure 4 TEM image of carbon quantum dots; Figure 5 TEM image of curcumin-carbon quantum dots; Figure 6 A graph showing the number of Staphylococcus aureus bacteria killed by curcumin-carbon quantum dots at different concentrations; Figure 7 The bactericidal effect of composite materials synthesized with different ratios of carbon quantum dots and curcumin is shown in the figure. Figure 8 The image shows the bactericidal effect of carbon quantum dot composite materials synthesized from different nitrogen sources. Detailed Implementation

[0019] This invention provides a method for preparing curcumin-carbon quantum dot composite nanomaterials, comprising the following steps: A mixture of an aqueous dispersion of carbon quantum dots and an ethanol solution of curcumin was used for loading to obtain curcumin-carbon quantum dot composite nanomaterials.

[0020] Unless otherwise specified, the present invention does not have special requirements on the source of raw materials used, and commercially available products well known to those skilled in the art can be used.

[0021] As one embodiment, the method for preparing the carbon quantum dots includes the following steps: A carbon source, an amino compound, and water are mixed and then stirred and sonicated sequentially. The resulting mixture undergoes a hydrothermal reaction to obtain carbon quantum dots.

[0022] As one implementation method, after the hydrothermal reaction, the process further includes: cooling the product obtained from the hydrothermal reaction to room temperature, and then sequentially performing solid-liquid separation, purification, and freeze-drying to obtain carbon quantum dots.

[0023] In one embodiment, the carbon source includes one or more of sodium citrate, citric acid, ascorbic acid, and chitosan, with sodium citrate being a specific example; the amino compound includes amino acids and / or amine compounds; the amino acid includes one or more of L-aspartic acid, lysine, and cysteine, with L-aspartic acid being a specific example; the amine compound includes ethylenediamine and / or urea, with urea being a specific example. The carbon source can provide the main carbon skeleton, and the amino compound can provide the modifying functional group - amino.

[0024] In one embodiment, the mass ratio of the carbon source to the amino compound is 2~4:1~2, specifically 4:2; the mass ratio of the carbon source to water is 2~4:20~30, specifically 3~4:30; the stirring is magnetic stirring; the stirring temperature is room temperature, specifically 25℃; the stirring speed is 200~300 rpm, specifically 300 rpm; the stirring time is 15~20 min, specifically 20 min; the ultrasonic power is 50~200W, specifically 100W, the frequency is 15~20kHz, specifically 20kHz, and the duration is 5~10 min, specifically 10 min. The hydrothermal reaction equipment is a Teflon-lined stainless steel high-pressure reactor; the hydrothermal reaction temperature is 160~200℃, specifically 180℃ in this embodiment, and the reaction time is 6~8h, specifically 6h in this embodiment; the cooling is natural cooling at room temperature or accelerated cooling in running water; the solid-liquid separation is filtration; the pore size of the filter membrane used for filtration is 0.22μm; the molecular weight cutoff of the dialysis bag used for purification is 500~1000kDa, specifically 800~1000kDa in this embodiment; the purification time is 48~72h, specifically 48h or 72h in this embodiment; the freeze-drying temperature is -30~-10℃, specifically -20℃ in this embodiment, and the reaction time is 48~72h, specifically 72h in this embodiment.

[0025] A series of key reactions, including dehydration, polymerization, cyclization, and carbonization, occur during the hydrothermal process. The hydrothermal reaction can form carbon cores with uniform size and good crystallinity, while nitrogen atoms from amino compounds such as L-aspartic acid can be effectively incorporated. If the hydrothermal reaction temperature is too low or the time is too short, sufficient carbonization and the formation of stable sp2+ cannot be achieved. 2 Carbon nuclei; if the hydrothermal reaction temperature is too high or the time is too long, the carbon nuclei grow too large, tending to form larger carbon nanoparticles or even amorphous carbon, losing the small size effect of quantum dots, and the surface functional groups are destroyed. This invention filters out impurities using a 0.22μm filter membrane.

[0026] In one embodiment, the concentration of curcumin in the ethanol solution of curcumin is 0.5~1 mg / mL, specifically 0.5 mg / mL or 1 mg / mL in the specific embodiment; the concentration of carbon quantum dots in the aqueous dispersion of carbon quantum dots is the same as the concentration of curcumin in the ethanol solution of curcumin; the volume ratio of the aqueous dispersion of carbon quantum dots to the ethanol solution of curcumin is 1~3:1, specifically 2:1 in the specific embodiment; the loading is carried out under stirring conditions; the stirring rate is 300~450 rpm, specifically 400 rpm in the specific embodiment; the loading temperature is room temperature; the loading time is 18~24 h, specifically 24 h in the specific embodiment.

[0027] In this invention, carbon dots are formed by hydrophobic interactions and π-π stacking, resulting from sp... 2 The graphite microcrystalline domains composed of hybrid carbon have an aromatic structure, and curcumin also has a strong hydrophobicity and planar aromatic structure; in addition, hydrogen bonds can be formed between the hydroxyl and carbonyl groups of curcumin molecules and the oxygen-containing functional groups on the surface of carbon quantum dots.

[0028] In one embodiment, after loading, the process further includes: sequentially subjecting the loaded product to rotary evaporation, centrifugal purification, and freeze-drying to obtain curcumin-carbon quantum dot composite nanomaterials; the rotary evaporation temperature is 40~60℃, specifically 50℃ in this embodiment, and the time is 10~20min, specifically 20min in this embodiment; the centrifugal purification rate is 8000~12000rpm, specifically 10000rpm in this embodiment; the number of centrifugal purification cycles is ≥3 times, specifically 3 times in this embodiment; the time for each centrifugal purification cycle is 10~15min, specifically 10min in this embodiment; the freeze-drying temperature is -30~-10℃, specifically -20℃ in this embodiment, and the time is 48~72h, specifically 72h in this embodiment.

[0029] This invention utilizes a hydrothermal method to prepare carbon quantum dots using L-aspartic acid and sodium citrate as precursors, and further loads them with curcumin to construct a curcumin-carbon quantum dot composite nanomaterial. This material not only significantly improves the water solubility of curcumin and the stability of the system, but also exhibits significantly enhanced antibacterial properties. Experiments show that the curcumin-carbon quantum dot composite nanomaterial has a significant concentration-dependent bactericidal effect against Staphylococcus aureus, achieving highly efficient sterilization even at low concentrations. Its antibacterial mechanism is mainly based on the following synergistic effects: on the one hand, carbon quantum dots can act as photosensitizers, generating reactive oxygen species under light conditions, thereby disrupting bacterial cell structure; on the other hand, curcumin molecules are stably loaded onto the carbon dot surface through π–π stacking and hydrogen bonding, allowing for controlled release within the bacterial microenvironment, directly acting on the cell membrane and metabolic system to jointly exert a highly efficient bactericidal effect. This composite material provides a new approach for developing natural, efficient, and stable food-grade antibacterial agents.

[0030] The present invention also provides a curcumin-carbon quantum dot composite nanomaterial prepared by the preparation method described in the above technical solution; the curcumin-carbon quantum dot composite nanomaterial is a near-spherical nanoparticle, comprising curcumin and carbon quantum dots; the curcumin is connected and embedded in the carbon quantum dots through hydrogen bonds.

[0031] In one embodiment, the particle size of the curcumin-carbon quantum dot composite nanomaterial is 5~20nm, and in a specific embodiment it is 10nm; the loading rate of curcumin in the curcumin-carbon quantum dot composite nanomaterial is 2.00~3.00wt%, and in a specific embodiment it is 2.80wt.

[0032] This invention also provides the application of the curcumin-carbon quantum dot composite nanomaterials described in the above technical solution in the preparation of antibacterial materials.

[0033] In one embodiment, the bacteria in the antibacterial material is Staphylococcus aureus.

[0034] The present invention does not impose any particular limitation on the application of the curcumin-carbon quantum dot composite nanomaterial in the preparation of antibacterial materials; any application method known in the art can be used.

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1 Carbon quantum dots were prepared by a high-temperature hydrothermal method: 4g of sodium citrate and 2g of L-aspartic acid were accurately weighed and dissolved in 30mL of purified water. After stirring magnetically at 300rpm for 15min at 25℃, the mixture was sonicated at 100W and 20kHz for 10min until fully dissolved. The dissolved mixture was then transferred to a 50mL Teflon-lined stainless steel high-pressure reactor and heated at 180℃ for 6h. After the product was allowed to cool naturally to room temperature, it was filtered through a 0.22μm filter membrane. The filtrate was then purified using a 1000kDa dialysis bag for 48h. Finally, the dialysis solution was dried at -20℃ for 72h using a freeze dryer to prepare carbon quantum dots. Curcumin was loaded using the ethanol encapsulation method: An aqueous dispersion of carbon quantum dots and an ethanol solution of curcumin (1 mg / mL) of the same concentration were prepared, and the loading was carried out according to V... 碳量子点 :V 姜黄素 Mix in a 2:1 ratio (volume ratio), stir the mixture at 400 rpm for 24 h at room temperature, and remove excess ethanol solution by rotary evaporation at 50 °C for 20 min. Centrifugation purification of samples: Centrifugation at 10,000 rpm was used to remove incompletely bound curcumin precipitate. Centrifugation was performed three times until no more yellow precipitate was produced. Each centrifugation lasted 10 min. The resulting supernatant was then dried at -20℃ for 72 h using a freeze dryer to obtain carbon quantum dot-curcumin composite nanomaterials (curcumin-carbon quantum dots) for subsequent experiments.

[0037] Example 2 The difference from Example 1 is that the concentration of curcumin in the ethanol solution of curcumin is 0.5 mg / mL.

[0038] Example 3 The difference from Example 1 is that L-aspartic acid in Example 1 is replaced with cysteine.

[0039] Example 4 The difference from Example 1 is that L-aspartic acid in Example 1 is replaced with urea.

[0040] Comparative Example 1 The difference from Example 1 is that the concentration of curcumin in the ethanol solution of curcumin is 0.1 mg / mL.

[0041] Comparative Example 2 The difference from Example 1 is that the concentration of curcumin in the ethanol solution of curcumin is 0.01 mg / mL.

[0042] Comparative Example 3 The difference from Example 1 is that V 碳量子点 :V 姜黄素 =10:1.

[0043] Comparative Example 4 The difference from Example 1 is that V 碳量子点 :V 姜黄素 =5:1.

[0044] Performance testing Characterization of curcumin-carbon quantum dot composite nanomaterials: 1. Determination of load rate Different concentrations of curcumin were dissolved in 50% ethanol aqueous solution, and the absorbance was recorded at 434 nm to prepare a standard curve. The absorbance of different samples (0.05 mg / mL) in 50% ethanol aqueous solution at 434 nm was recorded to calculate the curcumin loading rate.

[0045] 2. Determination of water solubility Curcumin, carbon quantum dots, and curcumin-carbon quantum dots were prepared at certain concentrations (1, 0.5, 0.1, and 0.01 mg / mL), and their absorption spectra were measured using an enzyme-linked immunosorbent assay (ELISA) reader in the range of 300–800 nm to analyze the changes in the absorption intensity of the samples.

[0046] 3. Stability determination Curcumin, carbon quantum dots, and curcumin-carbon quantum dots were prepared at certain concentrations (1, 0.5, 0.1, and 0.01 mg / mL), and the changes in the solutions were observed and photographed after standing for 10, 20, and 30 minutes.

[0047] 4. X-ray diffraction measurement After grinding, the sample was mounted using a micro-stage technique to ensure uniform dispersion and a smooth surface on a low-background silicon substrate. X-ray diffraction (XRD) tests were performed in θ-2θ continuous scanning mode with an operating voltage of 40 kV and a current of 40 mA. The scanning range was set to 5°~80° (2θ), with a step size of 0.02° and a scanning speed of 2° / min. The resulting diffraction patterns were smoothed and background subtracted before being processed using Jade software.

[0048] 5. Observation using transmission electron microscopy 1 mg of carbon quantum dots and curcumin-carbon quantum dots were weighed and dissolved in 2 mL of purified water. The mixture was sonicated for 10 min. The solution was then dropped onto the surface of an ultrathin carbon mesh and dried. Morphological images were then captured using a transmission electron microscope (TEM).

[0049] Solutions of curcumin, carbon quantum dots, and curcumin-carbon quantum dots at different concentrations were prepared to study their solubility. Figure 1 As shown in Figure A, the characteristic peaks of pure curcumin samples of different concentrations could not be detected, indicating that curcumin samples are difficult to dissolve and have poor water solubility. Figure 1 China B and Figure 1 In the C-type solution, characteristic peaks were observed at 350 nm for both carbon quantum dots and curcumin-carbon quantum dot solutions. This is due to the presence of carbon quantum dots. Electronic transitions; as the concentrations of carbon quantum dots and curcumin-carbon quantum dots increase, the peak intensity gradually increases, indicating that the water solubility of carbon quantum dots and curcumin-carbon quantum dots is enhanced compared to curcumin.

[0050] Meanwhile, the standard curve for curcumin was measured as y = 56.521x + 0.0497 (R²). 2 =0.9998), the absorption at 434 nm was measured in carbon quantum dots and curcumin-carbon quantum dots in 50% ethanol aqueous solution (0.05 mg / mL), and the loading rate of curcumin was calculated to be 0.15% for carbon quantum dots and 2.80% for curcumin-carbon quantum dots, indicating that curcumin has been successfully loaded onto the surface of carbon quantum dots.

[0051] Figure 2 Photographs of different solutions after standing for 0, 10, 20, and 30 minutes are provided to illustrate changes in their stability. Within the studied concentration range (0.01–1 mg / mL), the aqueous dispersion of curcumin was heterogeneous and in a mixed state; after standing, insoluble drug particles were clearly visible at the bottom. Figure 2 (A). After standing, the carbon quantum dots and curcumin-carbon quantum dot solution were evenly dispersed without any precipitate, exhibiting good water solubility and stability. The carbon quantum dot aqueous solution showed a light yellow-green color. Figure 2(B) The curcumin-carbon quantum dot solution exhibits a deeper yellow color due to the successful loading of curcumin. Figure 2 (C)

[0052] To investigate the crystal structure changes of curcumin and its complexes, X-ray diffraction was used to analyze curcumin, carbon quantum dots, and curcumin-carbon quantum dot samples. Figure 3 Curcumin exhibits unique crystal diffraction peaks at 2θ = 8.95°, 17.36°, 18.23°, and 24.74°, with sharp peaks and high intensity, indicating a highly ordered crystal structure. Carbon quantum dots do not show obvious sharp diffraction peaks, but rather broad and blunt diffuse peaks, indicating a predominantly amorphous structure. When curcumin is loaded onto carbon quantum dots, the main diffraction peaks are significantly weakened and broadened, especially a weak diffraction peak at 18.23°. Compared to curcumin, the crystallinity is significantly reduced; while compared to carbon quantum dots, it exhibits a certain degree of crystallinity. It displays a composite characteristic of curcumin and carbon quantum dots, with the crystal structure affected by the coating or doping of carbon quantum dots, leading to partial disruption of the crystal structure and thus reducing crystallinity. Furthermore, the amorphous structure improves the dispersibility and bioavailability of curcumin.

[0053] To investigate the encapsulation morphology of curcumin-carbon quantum dots, TEM images of carbon quantum dots and curcumin-carbon quantum dots were taken, as follows: Figure 4 and Figure 5 As shown, pure carbon quantum dots exhibit good dispersibility, with a spherical morphology and a size approximately 10 nm. Due to their abundant surface functional groups, carbon quantum dots are easily modified. Utilizing this property, curcumin is linked and embedded in carbon quantum dots via hydrogen bonds, exhibiting a morphology primarily similar to monodisperse carbon quantum dots. Curcumin appears as a modified functional group on the surface of the carbon quantum dots.

[0054] (1) Evaluation of the bactericidal effect of curcumin-carbon quantum dot composite nanomaterials Weigh 0.1 g of the curcumin-carbon quantum dot composite nanomaterial prepared in Example 1, dissolve it in 100 mL of deionized water, and prepare a stock solution with a concentration of 1 mg / mL. Dilute the Staphylococcus aureus suspension to a concentration of approximately 1 × 10⁻⁶. 7 CFU / mL. Subsequently, the curcumin-carbon quantum dot solution was mixed with the bacterial suspension, and the final concentrations of the complex were adjusted to 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, and 0.13 mg / mL. 10 mL of each concentration group was placed in a 6 cm diameter petri dish and irradiated under a xenon lamp. The vertical distance between the light source and the liquid surface was 35 cm, and the excitation current was set to 16 A to excite the curcumin-carbon quantum dots to exert their antibacterial effect. After 10 min of irradiation, samples were taken for colony counting to analyze changes in the survival rate of Staphylococcus aureus.

[0055] To evaluate the sterilization performance of the curcumin-carbon quantum dot composite material, its bactericidal effect against Staphylococcus aureus was determined, and the results are as follows: Figure 6 .like Figure 6 As shown, curcumin-carbon quantum dots exhibit significant antibacterial activity against Staphylococcus aureus. When the bacteria were treated with a complex solution at a concentration of 0.07 mg / mL, a bacterial reduction of approximately 3.33 logCFU / mL was achieved. Further increasing the complex concentration to 0.13 mg / mL enhanced the sterilization effect, achieving a bacterial kill of 5.17 logCFU / mL. The curcumin-carbon quantum dot composite material demonstrates high bactericidal potential even at low concentrations, and its antibacterial efficacy significantly increases with increasing concentration.

[0056] (2) The bactericidal effect of composite materials synthesized with different ratios of carbon quantum dots and curcumin After synthesizing carbon quantum dots according to the method described in the examples, aqueous solutions of carbon quantum dots and curcumin ethanol solutions (1 mg / mL) of the same concentration were prepared, and according to V 碳量子点 :V 姜黄素 The mixtures were prepared in volume ratios of 10:1, 5:1, and 2:1. The loading reaction was carried out under identical conditions (ethanol encapsulation method: same ethanol volume, temperature, and time). After the reaction, the mixtures were centrifuged, washed, and freeze-dried to obtain a series of compound powders, designated CurCDs-10, CurCDs-5, and CurCDs-2, respectively.

[0057] All the compound formulations were prepared into dispersions with the same solution concentration (0.1 mg / mL) using purified water. The same bactericidal test method as described above (same bacterial species, bacterial quantity, light conditions, and treatment time) was used to test the logCFU reduction value of each group against Staphylococcus aureus.

[0058] like Figure 7 As shown, under identical experimental conditions, the bactericidal effects of three composite materials with different ratios against Staphylococcus aureus were measured to be 3.82, 5.72, and 6.51 logCFU / mL, respectively. The data clearly indicate that the antibacterial activity of the composite material strongly depends on the mass ratio between the two components, and that there exists an optimal ratio that maximizes the bactericidal efficacy, namely: V... 碳量子点 V 姜黄素 =2:1. The antibacterial effect of curcumin-carbon quantum dot composites is not simply determined by their components, but is highly sensitive to the mass ratio of the two.

[0059] (3) Comparison of bactericidal effects of carbon quantum dot composite materials synthesized from different nitrogen sources Using sodium citrate as a uniform carbon source, three types of carbon quantum dots were synthesized under identical conditions by combining them with equal masses of L-aspartic acid (Example 1), cysteine, and urea as nitrogen sources. Subsequently, using a completely identical curcumin loading process, at a fixed mass ratio (V... 碳量子点 V 姜黄素 Curcumin was loaded onto these three types of carbon quantum dots in a ratio of 2:1 to prepare a series of composite materials. Finally, all composite materials were prepared into aqueous dispersions of the same concentration (0.1 mg / mL), and their bactericidal effect against Staphylococcus aureus was evaluated under uniform antibacterial test conditions, thus directly comparing the influence of carbon quantum dots synthesized from different nitrogen sources on the bactericidal performance of the final composite materials.

[0060] like Figure 8 As shown, when cysteine ​​or urea is used instead of aspartic acid as the nitrogen source, the bactericidal efficacy of the curcumin-carbon quantum dot composite material is significantly lower than that of L-aspartic acid. This confirms that the specific molecular structure of L-aspartic acid is crucial for constructing a synergistic antibacterial system with optimal performance, and its technical effect cannot be replaced by other common nitrogen sources.

[0061] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A preparation method of curcumin-carbon quantum dot composite nanomaterial, characterized in that, The method comprises the following steps: The carbon quantum dot aqueous dispersion and the curcumin ethanol solution are mixed to load curcumin-carbon quantum dot composite nanomaterials.

2. The production method according to claim 1, characterized by, The concentration of curcumin in the curcumin ethanol solution is 0.5-1 mg / mL; the concentration of carbon quantum dots in the carbon quantum dot aqueous dispersion is the same as the concentration of curcumin in the curcumin ethanol solution.

3. The production method according to claim 1 or 2, characterized by, The volume ratio of the carbon quantum dot aqueous dispersion to the curcumin ethanol solution is 1-3:

1.

4. The preparation method according to claim 1, characterized in that, The preparation method of the carbon quantum dots comprises the following steps: The carbon source, the amino compound and water are mixed, and stirring and ultrasonic are sequentially performed, and the obtained mixture is subjected to hydrothermal reaction to obtain carbon quantum dots.

5. The production method according to claim 4, characterized by, The carbon source comprises one or more of sodium citrate, citric acid, ascorbic acid and chitosan.

6. The preparation method according to claim 4, characterized in that, The amino compound comprises amino acid and / or amine compound; the amino acid comprises one or more of L-aspartic acid, lysine and cysteine; the amine compound comprises ethylenediamine and / or urea.

7. The preparation method according to claim 4, characterized in that, The mass ratio of the carbon source to the amino compound is 2-4:1-2.

8. The preparation method according to claim 4, characterized in that, The temperature of the hydrothermal reaction is 160-200 DEG C, and the time is 6-8 h.

9. The curcumin-carbon quantum dots composite nanomaterial prepared by the preparation method according to any one of claims 1-8, characterized in that, The curcumin-carbon quantum dot composite nanomaterials are near-spherical nanoparticles, comprising curcumin and carbon quantum dots; the curcumin is connected by hydrogen bond and embedded in the carbon quantum dots.

10. The use of the curcumin-carbon quantum dot composite nanomaterials in claim 9 in the preparation of antibacterial materials.

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