Rare earth coordination doped carbon quantum dots, and preparation method and application thereof

Abstract

The present application relates to the technical field of bacteriostatic agent, and particularly relates to a kind of rare earth coordination doped carbon quantum dots and its preparation method and application.The specific technical scheme is: the preparation method is: the mixed reaction system containing citric acid and / or citric acid derivative, histidine and / or histidine derivative, rare earth nitrate and solvent is reacted at 160~300 DEG C under oil bath for 2~8h, and rare earth coordination doped carbon quantum dots are prepared.The rare earth coordination doped carbon quantum dots prepared by the present application have excellent water solubility and antibacterial performance, the active sites on the surface of carbon quantum dots and the chemical coordination of rare earth ions, the synergistic antibacterial property of carbon quantum dots and rare earth ions is fully exerted;while good water-soluble performance effectively improves the dispersibility of bacteriostatic agent in water environment.

Description

Technical Field

[0001] This invention relates to the field of antibacterial agent technology, specifically to a rare earth coordination-doped carbon quantum dot, its preparation method, and its application. Background Technology

[0002] Microorganisms, due to their simple structure and powerful reproductive capabilities, are widely distributed in nature and closely related to our lives. Most microorganisms are harmless to human health, but a few can still cause harm. Harmful bacteria, as a class of pathogenic microorganisms, cause diseases. Escherichia coli and Staphylococcus aureus are two major pathogenic bacteria with wide distribution, posing a significant threat to human life and health.

[0003] Traditional clinical medicine typically uses antibiotics as the first-line treatment for bacterial infections. However, with the overuse and even dependence on antibiotics in clinical treatment, bacterial resistance is constantly increasing. The antibacterial efficacy of traditional antibacterial drugs has significantly decreased. Therefore, developing new antibacterial drugs that can more effectively inhibit or kill bacteria has become an urgent problem to be solved by the medical industry and related researchers. Currently, the key factors restricting the widespread use of traditional nano-antibacterial agents are their high cost, low biocompatibility, and potential toxicity. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a rare-earth coordination-doped carbon quantum dot, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention discloses a method for preparing rare earth coordination-doped carbon quantum dots, wherein a mixed reaction system containing citric acid and / or citric acid derivatives, histidine and / or histidine derivatives, rare earth nitrates and solvents is subjected to an oil bath reaction at 160-300°C for 2-8 hours to obtain rare earth coordination-doped carbon quantum dots.

[0007] Preferably, after the oil bath reaction is completed, the pH of the solution is adjusted to 3-7, and the obtained solution is then subjected to stirring, sonication, centrifugation, filtration, dialysis, and drying.

[0008] Preferably, the stirring time is 5 to 30 minutes;

[0009] And / or, the duration of the ultrasonic treatment is 5 to 30 minutes;

[0010] And / or, the centrifugation process is carried out at a speed of 6000-15000 r / min for a time of 5-30 min.

[0011] Preferably, the filtration process is vacuum filtration, and the filtration process is performed 1 to 3 times.

[0012] And / or, the dialysis bag used in the dialysis treatment has a molecular weight of 1 to 10 kDa;

[0013] And / or, the drying process is carried out at a temperature of 60–90°C for a time of 18–72 hours.

[0014] Preferably, the citric acid derivative includes at least one of ammonium citrate and hydroxycitric acid; the histidine derivative includes at least one of L-histidine and D-histidine; the rare earth nitrate includes at least one of cerium nitrate, lanthanum nitrate, and yttrium nitrate; and the solvent includes at least one of water, acid, and alkali.

[0015] Preferably, the mass ratio of the rare earth nitrate to citric acid and / or citric acid derivative is 1:100 to 25:100; the mass ratio of the histidine and / or histidine derivative to citric acid and / or citric acid derivative is 1:100 to 25:100.

[0016] Correspondingly, the rare earth coordination-doped carbon quantum dots prepared by the above preparation method are obtained.

[0017] Preferably, the constituent elements of the rare earth coordination-doped carbon quantum dots include C, H, O, N and rare earth ions, the rare earth ions in the rare earth coordination-doped carbon quantum dots coordinate with the N in the carbon quantum dots, the size of the rare earth coordination-doped carbon quantum dots is 2-30 nm, and the solubility of the rare earth coordination-doped carbon quantum dots in water is 5-200 mg / mL.

[0018] Accordingly, the rare earth coordination-doped carbon quantum dots prepared by the above preparation method can be used in the preparation of biological antibacterial agents, wherein the bacteria in the biological antibacterial agents include any one of Escherichia coli, Staphylococcus aureus, Candida, Aspergillus, etc.

[0019] Correspondingly, one method of using an antibacterial agent involves dissolving the rare earth coordination-doped carbon quantum dots prepared by the above method in water and spraying or coating them around bacteria.

[0020] The present invention has the following beneficial effects:

[0021] 1. The method for rare earth coordination doping of carbon quantum dots provided by the present invention has the advantages of convenient operation, low cost and environmental protection.

[0022] 2. The rare earth coordination-doped carbon quantum dots provided by this invention have excellent water solubility and antibacterial properties. The active sites on the surface of the carbon quantum dots and the chemical coordination of rare earth ions fully exert the synergistic antibacterial properties of carbon quantum dots and rare earth ions. At the same time, the good water solubility effectively improves the dispersibility of the antibacterial agent in the water environment.

[0023] 3. This invention prepares an antibacterial agent by reacting citric acid and / or citric acid derivatives, histidine and / or histidine derivatives, rare earth nitrates, and a solvent in an oil bath. The agent exhibits good water solubility and excellent antibacterial properties, and can be applied in industries such as biology, medicine, chemicals, shipbuilding, storage, and marine applications. Using this antibacterial agent in biomedicine can improve antibacterial efficacy and reduce bacterial resistance. When used in bacterial environments, it can also reduce bacterial growth rates. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the preparation process of the present invention;

[0025] Figure 2 TEM image of rare earth coordination-doped carbon quantum dots prepared in Example 1;

[0026] Figure 3 The inhibition rate of the blank carbon quantum dot sample in Comparative Example 1 against Staphylococcus aureus and Escherichia coli is shown.

[0027] Figure 4 The inhibition rate of the blank carbon quantum dot sample in Comparative Example 2 against Candida and Aspergillus is shown.

[0028] Figure 5 The inhibition rate of the blank carbon quantum dot sample in Comparative Example 3 against Pseudomonas aeruginosa and Acinetobacter baumannii was calculated.

[0029] Figure 6 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 1 against Staphylococcus aureus;

[0030] Figure 7 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 1 against Escherichia coli;

[0031] Figure 8 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 2 against Staphylococcus aureus;

[0032] Figure 9 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 2 against Escherichia coli;

[0033] Figure 10 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 3 against Staphylococcus aureus;

[0034] Figure 11 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 3 against Escherichia coli;

[0035] Figure 12 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 4 against Staphylococcus aureus;

[0036] Figure 13 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 4 against Escherichia coli;

[0037] Figure 14 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 5 against Escherichia coli;

[0038] Figure 15 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 5 against Staphylococcus aureus;

[0039] Figure 16 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 6 against Escherichia coli;

[0040] Figure 17 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 6 against Staphylococcus aureus;

[0041] Figure 18 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 7 against Candida albicans;

[0042] Figure 19 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 7 against Aspergillus;

[0043] Figure 20 The antibacterial rate of rare earth coordination-doped carbon quantum dots prepared in Example 8 against Pseudomonas aeruginosa;

[0044] Figure 21 The inhibition rate of rare earth coordination-doped carbon quantum dots prepared in Example 8 against Acinetobacter baumannii. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0046] 1. This invention discloses a method for preparing rare-earth coordination-doped carbon quantum dots, the preparation process of which is shown in the schematic diagram below. Figure 1 As shown. The preparation process is as follows: a mixed reaction system containing citric acid and / or citric acid derivatives, histidine and / or histidine derivatives, rare earth nitrates and solvents is subjected to an oil bath reaction at 160-300℃ for 2-8 hours to obtain rare earth coordination-doped carbon quantum dots.

[0047] Furthermore, after the oil bath reaction is completed, the pH of the solution is adjusted to 3-7, and the obtained solution is then subjected to stirring, sonication, centrifugation, filtration, dialysis, and drying. The pH can be adjusted using hydrochloric acid and sodium hydroxide.

[0048] The stirring treatment lasts for 5–30 minutes, the ultrasonic treatment lasts for 5–30 minutes, and the centrifugation treatment lasts for 5–30 minutes at a speed of 6000–15000 r / min. The filtration treatment uses qualitative filter paper for vacuum filtration, and the filtration is performed 1–3 times. The dialysis treatment uses dialysis bags with a molecular weight of 1–10 KD. The drying treatment is performed at a temperature of 60–90℃ for 18–72 hours.

[0049] Furthermore, the citric acid derivative includes, but is not limited to, at least one of ammonium citrate and hydroxycitric acid; the histidine derivative includes, but is not limited to, at least one of L-histidine and D-histidine; the rare earth nitrate includes, but is not limited to, at least one of cerium nitrate, lanthanum nitrate, and yttrium nitrate; and the solvent includes, but is not limited to, at least one of water, acid, and alkali.

[0050] Furthermore, the mass ratio of the rare earth nitrate to citric acid and / or citric acid derivative is 1:100 to 25:100; the mass ratio of the histidine and / or histidine derivative to citric acid and / or citric acid derivative is 1:100 to 25:100.

[0051] 2. The rare-earth coordination-doped carbon quantum dots prepared according to the above method mainly consist of C, H, O, N, and rare-earth ions. The rare-earth ions in the rare-earth coordination-doped carbon quantum dots coordinate with the N in the carbon quantum dots. The size of the rare-earth coordination-doped carbon quantum dots is 2–30 nm, and they exhibit excellent dispersibility in an aqueous environment. The solubility of the rare-earth coordination-doped carbon quantum dots in water is 5–200 mg / mL, indicating that they possess excellent water solubility.

[0052] 3. The application of rare earth coordination-doped carbon quantum dots prepared by the above preparation method in the preparation of biological antibacterial agents, wherein the bacteria in the biological antibacterial agents include any one of Escherichia coli, Staphylococcus aureus, Candida, Aspergillus, etc.

[0053] Experimental results showed that after 24 hours of growth in rare-earth-doped carbon quantum dots, *Escherichia coli* and *Staphylococcus aureus* maintained an inhibition rate of over 90% compared to solutions without rare-earth-doped carbon quantum dots, demonstrating excellent antibacterial properties. The inhibition rate was reduced by 1–2 times compared to solutions without carbon quantum dots.

[0054] After 24 hours of growth in rare-earth coordinated doped carbon quantum dots, the inhibition rate of Candida and Aspergillus remained above 90% compared to solutions without rare-earth coordinated doped carbon quantum dots. The inhibition rate was reduced by 1–2 times compared to solutions without carbon quantum dots.

[0055] After 24 hours of growth in rare-earth-doped carbon quantum dots, *Pseudomonas aeruginosa* and *Acinetobacter baumannii* still maintained an inhibition rate of over 90% compared to solutions without rare-earth-doped carbon quantum dots. The inhibition rate was reduced by 1–2 times compared to solutions without carbon quantum dots.

[0056] The present invention will be further described below with reference to specific embodiments.

[0057] Example 1

[0058] The preparation process of the antibacterial agent is as follows:

[0059] (1) Dissolve 2g of citric acid, 0.2g of L-histidine, and 0.2g of cerium nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir the solution for 10min, then sonicate for 10min, and then filter and centrifuge. The centrifugation speed is 10000r / min and the time is 10min.

[0060] (2) Dialysis was then performed, and the molecular weight of the dialysis bag was 2KD. Finally, the dialysate was dried in a vacuum drying oven at 80℃ to obtain rare earth coordination-doped carbon quantum dots with the following morphology. Figure 2 As shown.

[0061] (3) Subsequently, a certain amount of rare earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Staphylococcus aureus and Escherichia coli solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Staphylococcus aureus and Escherichia coli under different concentrations of rare earth coordination-doped carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 6 and 7 As shown.

[0062] Example 2

[0063] The preparation process of the antibacterial agent is as follows:

[0064] (1) Dissolve 2g of citric acid, 0.2g of L-histidine, and 0.2g of lanthanum nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir the solution for 10min, then sonicate for 10min, and then filter and centrifuge. The centrifugation speed is 10000r / min and the time is 10min.

[0065] (2) Then, dialysis was performed, and the molecular weight of the dialysis bag was 2KD. Finally, the dialysis solution was placed in a vacuum drying oven at 80℃ to dry, and rare earth coordinated doped carbon quantum dots were obtained.

[0066] (3) Subsequently, a certain amount of rare earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Staphylococcus aureus and Escherichia coli solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Staphylococcus aureus and Escherichia coli under different concentrations of rare earth coordination-doped carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 8 and 9 As shown.

[0067] Example 3

[0068] The preparation process of the antibacterial agent is as follows:

[0069] (1) Dissolve 2g of citric acid, 0.2g of L-histidine, and 0.2g of yttrium nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir the solution for 10min, then sonicate for 10min, and then filter and centrifuge. The centrifugation speed is 10000r / min and the time is 10min.

[0070] (2) Then, dialysis was performed, and the molecular weight of the dialysis bag was 2KD. Finally, the dialysis solution was placed in a vacuum drying oven at 80℃ to dry, and rare earth coordinated doped carbon quantum dots were obtained.

[0071] (3) Subsequently, a certain amount of rare earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Staphylococcus aureus and Escherichia coli solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Staphylococcus aureus and Escherichia coli under different concentrations of rare earth coordination-doped carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 10 and 11 As shown.

[0072] Example 4

[0073] The preparation process of the antibacterial agent is as follows:

[0074] (1) Dissolve 2g of citric acid, 0.2g of L-histidine, and 0.1g of lanthanum nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir the solution for 10min, then sonicate for 10min, and then filter and centrifuge. The centrifugation speed is 10000r / min and the time is 10min.

[0075] (2) Then, dialysis was performed, and the molecular weight of the dialysis bag was 2KD. Finally, the dialysis solution was placed in a vacuum drying oven at 80℃ to dry, and rare earth coordinated doped carbon quantum dots were obtained.

[0076] (3) Subsequently, a certain amount of rare earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Staphylococcus aureus and Escherichia coli solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Staphylococcus aureus and Escherichia coli under different concentrations of rare earth coordination-doped carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 12 and 13 As shown.

[0077] Example 5

[0078] The preparation process of the antibacterial agent is as follows:

[0079] (1) Dissolve 2g of citric acid, 0.1g of L-histidine, and 0.2g of lanthanum nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir the solution for 10min, then sonicate for 10min, and then filter and centrifuge. The centrifugation speed is 10000r / min and the time is 10min.

[0080] (2) Then, dialysis was performed, and the molecular weight of the dialysis bag was 2KD. Finally, the dialysis solution was placed in a vacuum drying oven at 80℃ to dry, and rare earth coordinated doped carbon quantum dots were obtained.

[0081] (3) Subsequently, a certain amount of rare earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Staphylococcus aureus and Escherichia coli solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Staphylococcus aureus and Escherichia coli under different concentrations of rare earth coordination-doped carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 14 and 15As shown.

[0082] Example 6

[0083] The preparation process of the antibacterial agent is as follows:

[0084] (1) Dissolve 2g of citric acid, 0.2g of L-histidine, and 0.2g of lanthanum nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 250℃ for 6h. After the reaction is complete, adjust the pH of the solution to 6, stir the solution for 15min, then sonicate for 15min, and then filter and centrifuge. The centrifugation speed is 12000r / min and the time is 10min.

[0085] (2) Then, dialysis was performed, and the molecular weight of the dialysis bag was 3KD. Finally, the dialysis solution was placed in a vacuum drying oven at 85℃ to obtain rare earth coordinated doped carbon quantum dots.

[0086] (3) Subsequently, a certain amount of rare earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Staphylococcus aureus and Escherichia coli solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Staphylococcus aureus and Escherichia coli under different concentrations of rare earth coordination-doped carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 16 and 17 As shown.

[0087] Example 7

[0088] The preparation process of the antibacterial agent is as follows:

[0089] (1) Dissolve 2g of citric acid, 0.2g of L-histidine, and 0.2g of lanthanum nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir the solution for 10min, then sonicate for 10min, and then filter and centrifuge. The centrifugation speed is 10000r / min and the time is 10min.

[0090] (2) Then, dialysis was performed, and the molecular weight of the dialysis bag was 2KD. Finally, the dialysis solution was placed in a vacuum drying oven at 80℃ to dry, and rare earth coordinated doped carbon quantum dots were obtained.

[0091] (3) Subsequently, a certain amount of rare earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Candida and Aspergillus solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Candida and Aspergillus under different concentrations of rare earth coordination-doped carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 18 and 19 As shown.

[0092] Example 8

[0093] The preparation process of the antibacterial agent is as follows:

[0094] (1) Dissolve 2g of citric acid, 0.2g of L-histidine, and 0.2g of lanthanum nitrate in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir the solution for 10min, then sonicate for 10min, and then filter and centrifuge. The centrifugation speed is 10000r / min and the time is 10min.

[0095] (2) Then, dialysis was performed, and the molecular weight of the dialysis bag was 2KD. Finally, the dialysis solution was placed in a vacuum drying oven at 80℃ to dry, and rare earth coordinated doped carbon quantum dots were obtained.

[0096] (3) Subsequently, a certain amount of rare-earth coordination-doped carbon quantum dots were added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Solutions of *Pseudomonas aeruginosa* and *Acinetobacter baumannii* were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of *Pseudomonas aeruginosa* and *Acinetobacter baumannii* under different concentrations of rare-earth coordination-doped carbon quantum dots were measured using the plate counting method. The inhibition rate of bacteria was compared with that obtained after free bacterial growth. Figure 20 and 21 As shown.

[0097] Comparative Example 1

[0098] The preparation process is as follows:

[0099] (1) Dissolve 2g of citric acid in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir for 10min, then sonicate for 10min, then filter and centrifuge at 10000r / min for 10min. After centrifugation, dialyze the solution. The molecular weight of the dialysis bag is 2KD. Finally, dry the dialysate in a vacuum drying oven at 80℃ to obtain citric acid carbon quantum dots.

[0100] (2) Subsequently, a certain amount of citrate carbon quantum dots was added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Staphylococcus aureus and Escherichia coli solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Staphylococcus aureus and Escherichia coli under different concentrations of citrate carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 3 As shown.

[0101] Comparative Example 2

[0102] The preparation process is as follows:

[0103] (1) Dissolve 2g of citric acid in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir for 10min, then sonicate for 10min, then filter and centrifuge at 10000r / min for 10min. After centrifugation, dialyze the solution. The molecular weight of the dialysis bag is 2KD. Finally, dry the dialysate in a vacuum drying oven at 80℃ to obtain citric acid carbon quantum dots.

[0104] (2) Subsequently, a certain amount of citrate carbon quantum dots was added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Candida and Aspergillus solutions were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of Candida and Aspergillus under different concentrations of citrate carbon quantum dots were measured using the plate count method. The bacterial inhibition rate was compared with that obtained after free bacterial growth. Figure 4 As shown.

[0105] Comparative Example 3

[0106] The preparation process is as follows:

[0107] (1) Dissolve 2g of citric acid in 60mL of deionized water, then transfer the solution to a single-necked flask and react at 200℃ for 2h. After the reaction is complete, adjust the pH of the solution to 4, stir for 10min, then sonicate for 10min, then filter and centrifuge at 10000r / min for 10min. After centrifugation, dialyze the solution. The molecular weight of the dialysis bag is 2KD. Finally, dry the dialysate in a vacuum drying oven at 80℃ to obtain citric acid carbon quantum dots.

[0108] (2) Subsequently, a certain amount of citrate carbon quantum dots was added to deionized water to prepare solutions with concentrations of 5, 10, 15, and 20 mg / L. Solutions of *Pseudomonas aeruginosa* and *Acinetobacter baumannii* were mixed with the above carbon quantum dot solutions. After culturing for 24 hours, the changes in the number of *Pseudomonas aeruginosa* and *Acinetobacter baumannii* under different concentrations of citrate carbon quantum dots were measured using the plate count method. The inhibition rate of bacteria was compared with that obtained after free growth. Figure 5 As shown.

[0109] The results show:

[0110] (1) Statistical analysis of the antibacterial rates of rare earth coordination-doped carbon quantum dots prepared in Comparative Example 1, Examples 1, 2, and 3 against Staphylococcus aureus and Escherichia coli revealed that, for example... Figure 3 As shown, at concentrations of 5, 10, 15, and 20 mg / L, the inhibition rates of blank carbon quantum dots against Staphylococcus aureus were 14%, 22%, 24%, and 28%, respectively, and against Escherichia coli were 20%, 24%, 29%, and 31%, respectively.

[0111] After rare earth cerium coordination, such as Figure 6 and 7 As shown, the rare earth cerium-coordinated doped carbon quantum dots exhibited inhibition rates of 72%, 85%, 89%, and 94% against Staphylococcus aureus, representing increases of 5.1, 3.9, 3.7, and 3.4 times, respectively; and inhibition rates against Escherichia coli were 76%, 88%, 92%, and 96%, representing increases of 3.8, 3.7, 3.2, and 3.1 times, respectively.

[0112] After coordination with rare earth lanthanum, such as Figure 8 and 9 As shown, the inhibition rates of rare earth lanthanum-coordinated doped carbon quantum dots against Staphylococcus aureus were 68%, 79%, 85%, and 93%, respectively, representing increases of 4.9, 3.6, 3.5, and 3.3 times; and the inhibition rates against Escherichia coli were 71%, 86%, 91%, and 95%, respectively, representing increases of 3.6, 3.6, 3.1, and 3.1 times.

[0113] After rare earth yttrium coordination, such as Figure 10 and 11 As shown, the inhibition rates of rare earth yttrium-coordinated doped carbon quantum dots against Staphylococcus aureus were 70%, 82%, 88%, and 92%, respectively, representing increases of 5.0, 3.7, 3.7, and 3.3 times; and the inhibition rates against Escherichia coli were 56%, 75%, 80%, and 86%, respectively, representing increases of 2.8, 3.1, 2.8, and 2.8 times.

[0114] (2) Statistical analysis of the antibacterial rates of rare-earth coordination-doped carbon quantum dots prepared in Comparative Examples 1, 4, 5, and 6 against Staphylococcus aureus and Escherichia coli revealed that, for example... Figure 3 As shown, at concentrations of 5, 10, 15, and 20 mg / L, the inhibition rates of blank carbon quantum dots against Staphylococcus aureus were 14%, 22%, 24%, and 28%, respectively, and against Escherichia coli were 20%, 24%, 29%, and 31%, respectively.

[0115] After coordination with rare earth lanthanum, such as Figure 12 and 13 As shown, the inhibition rates of rare-earth lanthanum-coordinated doped carbon quantum dots against Staphylococcus aureus were 59%, 72%, 84%, and 90%, respectively, representing increases of 4.2, 3.3, 3.5, and 3.2 times; and against Escherichia coli, the inhibition rates were 64%, 79%, 87%, and 92%, respectively, representing increases of 3.2, 3.3, 3.0, and 3.0 times. Figure 14 and 15 As shown, the inhibition rates of rare-earth lanthanum-coordinated doped carbon quantum dots against Staphylococcus aureus were 54%, 69%, 77%, and 84%, respectively, representing increases of 3.9, 3.1, 2.8, and 3.0 times; and the inhibition rates against Escherichia coli were 58%, 72%, 81%, and 88%, respectively, representing increases of 2.9, 3.0, 2.8, and 2.8 times. Figure 16 and 17 As shown, the inhibition rates of rare earth lanthanum-coordinated doped carbon quantum dots against Staphylococcus aureus were 66%, 77%, 85%, and 91%, respectively, representing increases of 4.7, 3.5, 3.5, and 3.3 times; and the inhibition rates against Escherichia coli were 62%, 74%, 88%, and 93%, respectively, representing increases of 3.1, 3.1, 3.0, and 3.0 times.

[0116] (3) Statistical analysis of the antibacterial rates of rare-earth coordination-doped carbon quantum dots prepared in Examples 2, 4, and 5 against Staphylococcus aureus and Escherichia coli revealed that, for example... Figure 8 and 9 As shown, the inhibition rates of rare earth lanthanum-coordinated doped carbon quantum dots against Staphylococcus aureus were 68%, 79%, 85%, and 93%, respectively, and against Escherichia coli were 71%, 86%, 91%, and 95%, respectively.

[0117] As the content of lanthanum nitrate decreases, such as Figure 12 and 13 As shown, the inhibition rates of rare earth lanthanum-coordinated doped carbon quantum dots against Staphylococcus aureus were 59%, 72%, 84%, and 90%, respectively, representing reductions of 9%, 7%, 1%, and 3%; and the inhibition rates against Escherichia coli were 64%, 79%, 87%, and 92%, respectively, representing reductions of 7%, 7%, 4%, and 3%.

[0118] As the content of histidine decreases, such as Figure 14 and 15 As shown, the inhibition rates of rare earth lanthanum-coordinated doped carbon quantum dots against Staphylococcus aureus were 54%, 69%, 77%, and 84%, respectively, representing reductions of 14%, 10%, 8%, and 9%; and the inhibition rates against Escherichia coli were 58%, 72%, 81%, and 88%, respectively, representing reductions of 13%, 14%, 10%, and 7%.

[0119] (4) Statistical analysis of the antibacterial rates of rare-earth coordination-doped carbon quantum dots prepared in Comparative Example 2 and Example 7 against Candida and Aspergillus revealed that, Figure 4 As shown, at concentrations of 5, 10, 15, and 20 mg / L, the inhibition rates of blank carbon quantum dots against Candida were 8%, 11%, 16%, and 19%, respectively, and against Aspergillus were 11%, 12%, 18%, and 22%, respectively.

[0120] After coordination with rare earth lanthanum, such as Figure 18 and 19 As shown, the inhibition rates of rare earth lanthanum-coordinated doped carbon quantum dots against Candida albicans were 57%, 72%, 84%, and 90%, respectively, representing increases of 7.1, 6.5, 5.3, and 4.7 times; and the inhibition rates against Aspergillus were 64%, 79%, 87%, and 92%, respectively, representing increases of 3.2, 3.3, 3.0, and 3.0 times.

[0121] (5) Statistical analysis of the antibacterial rates of rare-earth coordination-doped carbon quantum dots prepared in Comparative Example 3 and Example 8 against *Pseudomonas aeruginosa* and *Acinetobacter baumannii* revealed that, for example... Figure 5 As shown, at concentrations of 5, 10, 15, and 20 mg / L, the inhibition rates of blank carbon quantum dots against Pseudomonas aeruginosa were 8%, 13%, 17%, and 27%, respectively, and against Acinetobacter baumannii were 6%, 12%, 14%, and 19%, respectively.

[0122] After coordination with rare earth lanthanum, such as Figure 20 and 21 As shown, the inhibition rates of rare earth lanthanum-coordinated doped carbon quantum dots against Pseudomonas aeruginosa were 48%, 64%, 81%, and 89%, respectively, representing increases of 6.0, 4.9, 4.8, and 3.3 times; and the inhibition rates against Acinetobacter baumannii were 42%, 66%, 78%, and 84%, respectively, representing increases of 7.0, 5.5, 5.6, and 4.4 times.

[0123] In addition, the inventors also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the foregoing embodiments, and obtained relatively ideal results.

[0124] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing rare-earth coordination-doped carbon quantum dots, characterized in that: Rare earth coordination-doped carbon quantum dots are prepared by subjecting a mixed reaction system containing citric acid or citric acid derivatives, histidine, rare earth nitrates and solvent to an oil bath reaction at 160–300 °C for 2–8 h. The citric acid derivative is at least one of ammonium citrate and hydroxycitric acid; the histidine includes at least one of L-histidine and D-histidine; the rare earth nitrate includes at least one of cerium nitrate, lanthanum nitrate, and yttrium nitrate; the solvent includes at least one of water, acid, and alkali. The mass ratio of the rare earth nitrate to citric acid or citric acid derivative is 1:100 to 25:100; the mass ratio of the histidine to citric acid or citric acid derivative is 1:100 to 25:

100.

2. The method of claim 1, wherein: After the oil bath reaction is completed, the pH of the solution is adjusted to 3-7, and the obtained solution is then subjected to stirring, sonication, centrifugation, filtration, dialysis, and drying.

3. The method of claim 2, wherein: The stirring process takes 5 to 30 minutes. Alternatively, the ultrasonic treatment time is 5 to 30 minutes; Alternatively, the centrifugation process can be carried out at a speed of 6000–15000 r / min for a duration of 5–30 min.

4. The preparation method according to claim 2, characterized in that: The filtration process is vacuum filtration, and the filtration process is repeated 1 to 3 times. Alternatively, the dialysis bag used in the dialysis treatment has a molecular weight of 1 to 10 kDa; Alternatively, the drying process may be carried out at a temperature of 60–90°C for 18–72 hours.

5. The rare-earth coordination-doped carbon quantum dots prepared by the preparation method according to any one of claims 1 to 4 are characterized in that: The rare earth ions in the rare earth coordination-doped carbon quantum dots coordinate with the N in the carbon quantum dots. The size of the rare earth coordination-doped carbon quantum dots is 2-30 nm, and the solubility of the rare earth coordination-doped carbon quantum dots in water is 5-200 mg / mL.

Images