A broad-spectrum antibacterial carbon quantum dot and its preparation method and application

Abstract

The present invention belongs to the technical field of antibacterial nanomaterials, and specifically provides a broad-spectrum antibacterial carbon quantum dot, a preparation method thereof, and an application thereof. The broad-spectrum antibacterial carbon quantum dot is obtained by subjecting radix dahurica powder or radix dahurica residue to a hydrothermal reaction in an aqueous environment; the temperature of the hydrothermal reaction is 120°C to 200°C, and the time is 6h to 8h. The radix dahurica residue is the radix dahurica residue after polysaccharide extraction. The broad-spectrum antibacterial carbon quantum dots in the present invention have a good inhibitory effect on both bacteria and fungi, the entire preparation process is simple and environmentally friendly, and the radix dahurica residue carbon quantum dots show a strong inhibitory ability against Penicillium expansum.

Description

Technical Field

[0001] The present invention belongs to the technical field of antibacterial nanomaterials, and specifically relates to broad-spectrum antibacterial carbon quantum dots, a preparation method thereof, and applications thereof. Background Art

[0002] Bacterial infections have become a major threat to public health, and the widespread use of antibiotics has led to the development of bacterial resistance. As more bacteria develop multidrug resistance, treating infections becomes increasingly difficult, making the search for new methods to inhibit them crucial. Penicillium expansum is a common spoilage fungus found in fruit. Its metabolites may remain in processed fruit products, potentially causing acute and chronic toxicity and cytopathic effects upon consumption, posing a serious health threat. Currently, traditional methods primarily rely on physical and chemical means to inhibit the growth and reproduction of Penicillium expansum. However, physical methods such as low-temperature storage, drying, and irradiation can effectively slow fungal growth but can increase costs and compromise food quality or safety. Chemical methods, including the use of chemical preservatives, fumigation, and biological preservatives, while highly effective in killing bacteria, also carry health risks, environmental impacts, and cost issues, limiting their practical application.

[0003] Carbon quantum dots (CQDs) are a novel nanomaterial, less than 10 nanometers in size, with excellent optical properties, good water dispersibility, a modifiable surface, and good biocompatibility. They are widely used in biological and medical fields, such as bioimaging, biosensing, drug delivery, therapy, and detection. In recent years, researchers have increasingly focused on the antimicrobial effects of CQDs. Studies have confirmed their inhibitory effects on bacteria, but existing CQDs do not inhibit both bacteria and fungi. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a broad-spectrum antibacterial carbon quantum dots and a preparation method and application thereof, which can inhibit bacteria and fungi at the same time.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions.

[0006] The first aspect of the present invention provides a broad-spectrum antibacterial carbon quantum dot, which is obtained by subjecting genkwa powder or genkwa residue to a hydrothermal reaction in an aqueous environment, filtering and discarding the sediment, and concentrating;

[0007] The temperature of the hydrothermal reaction is 120°C to 200°C, and the time is 6h to 8h;

[0008] The mass volume ratio of the genus dahurica powder or genus dahurica residue to water is 1g-1.2g:60mL;

[0009] The genus dahurica residue is obtained by ultrasonic-assisted water extraction of polysaccharides.

[0010] The genus croton powder or genus croton residue of the present invention is subjected to a hydrothermal reaction in an aqueous environment, and the temperature and time of the hydrothermal reaction are controlled so that the obtained broad-spectrum antibacterial carbon quantum dots have a good inhibitory effect on both bacteria and fungi. The genus croton residue obtained by ultrasonic-assisted water extraction of polysaccharides is selected. This is mainly because different polysaccharide extraction methods may produce different degrees of impurity residues. The presence of these impurities may interfere with the synthesis process of the carbon quantum dots, thereby affecting the performance of the carbon quantum dots. Therefore, the present invention uses the genus croton residue obtained by ultrasonic-assisted hot water extraction of polysaccharides.

[0011] In another preferred embodiment, the genus trehalose residue is obtained in the following manner:

[0012] The genus Dahuricae is mixed with water, subjected to ultrasonic extraction at 60° C. to 65° C. for 50 min to 55 min, filtered, the precipitate is dried, and crushed to obtain the genus Dahuricae residue;

[0013] The power of the ultrasound is 350W to 360W.

[0014] The second aspect of the present invention provides a method for preparing the broad-spectrum antibacterial carbon quantum dots, comprising the following steps:

[0015] The genus dahurica powder or genus dahurica residue is mixed with water, subjected to hydrothermal reaction at 120°C to 200°C for 6h to 8h, filtered, allowed to stand and cool to 20°C to 24°C, the sediment is discarded to obtain a solution, the solution is filtered through a filter membrane to obtain a filtrate, and the filtrate is concentrated to obtain the broad-spectrum antibacterial carbon quantum dots.

[0016] In another preferred embodiment, the filter membrane is a 0.45 μm water ultrafiltration membrane.

[0017] The third aspect of the present invention provides the use of the broad-spectrum antibacterial carbon quantum dots in the preparation of antifungal products.

[0018] In another preferred embodiment, the fungus is Penicillium expansum.

[0019] The fourth aspect of the present invention provides the use of the broad-spectrum antibacterial carbon quantum dots in the preparation of antibacterial products.

[0020] In another preferred embodiment, the bacteria are one or both of Escherichia coli and Staphylococcus aureus.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention controls the hydrothermal reaction temperature between 120°C and 200°C in a water environment and reacts for 6h to 8h to obtain broad-spectrum antibacterial carbon quantum dots that have good antibacterial effects on both bacteria and fungi. The genus genus residue in the present invention is obtained by ultrasonic-assisted water extraction of polysaccharides, which can reduce impurities in the genus genus residue and thus avoid interference in the synthesis process of carbon quantum dots. The genus genus in the present invention is both medicinal and edible, and the entire preparation process is simple and environmentally friendly. In addition, the carbon quantum dots of the genus genus residue show a strong inhibitory ability against Penicillium expansum.

[0023] (2) This invention effectively utilizes the medicinal and edible plant, Daphne radix, to develop a new green and environmentally friendly antibacterial material with good biocompatibility and environmental friendliness. The inhibitory effect of carbon quantum dots on Penicillium expansum was explored, providing a new prevention and control method for the food processing and preservation fields, and is expected to improve food safety and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The diagram shows the Fourier transform infrared spectroscopy characterization and analysis of the carbon quantum dots of genkwa powder and genkwa residue powder in Examples 1 to 6 of the present invention.

[0025] Figure 2 Graph showing the inhibitory effects of the six genus genus carbon dots on Escherichia coli in Examples 1 to 6 of the present invention.

[0026] Figure 3 Graph showing the inhibitory effects of six types of genus genkwa residue carbon dots on Escherichia coli in Examples 1 to 6 of the present invention.

[0027] Figure 4 Graph showing the inhibitory effects of the six genus genus carbon dots on Staphylococcus aureus in Examples 1 to 6 of the present invention.

[0028] Figure 5 Graph showing the inhibitory effects of six types of genus genkwa residue carbon dots on Staphylococcus aureus in Examples 1 to 6 of the present invention.

[0029] Figure 6 Graph showing the inhibitory effects of six types of genus genkwa residue carbon dots on Penicillium expansum in Examples 1 to 6 of the present invention.

[0030] Figure 7 Figures 1 and 2 show the inhibitory effects of different concentrations of Z160 / 12 on Penicillium expansum in Example 1 of the present invention, wherein A is the inhibitory effect of the blank control group, B is the inhibitory effect of 4.76 mg / mL Z160 / 12 on Penicillium expansum, and C is the inhibitory effect of 0.48 mg / mL Z160 / 12 on Penicillium expansum. DETAILED DESCRIPTION

[0031] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Unless otherwise specified, the methods described in the embodiments of the present invention are conventional methods. The materials and reagents used are all commercially available unless otherwise specified.

[0033] Preparation of coriander root powder: Dry the fresh coriander root slices at 60℃ for 12 hours, grind them into powder and set aside.

[0034] Preparation of genus dahurica residue powder: genus dahurica was mixed with water at a solid-liquid ratio of 1 g:43 mL, and ultrasonic extraction was performed at 60°C for 55 min, wherein the ultrasonic power was 360 W, the precipitate was filtered, and the precipitate was dried at 60°C for 12 h and then crushed to obtain genus dahurica residue powder.

[0035] The present invention does not limit the particle size of the genus dahurica powder and the genus dahurica residue powder, and they can be crushed using existing technology.

[0036] Staphylococcus aureus (ATCC25923) and Escherichia coli (ATCC25922) were purchased from Haibo Biotechnology Co., Ltd. in Qingdao High-Tech Industrial Park. Penicillium expansum was kindly donated by Researcher Tian Shiping of the Institute of Botany, Chinese Academy of Sciences and stored at −80°C.

[0037] Example 1

[0038] A method for preparing carbon quantum dots from radix quinquefolii, comprising the following steps:

[0039] S1. Take 1 g of genkwa root powder and 1 g of genkwa root residue powder, add 60 mL of distilled water respectively, stir magnetically for 10 min, then transfer to a high-pressure reactor, place it at 120 ° C for hydrothermal reaction for 6 h, filter and discard the sediment to obtain a solution, and let the solution stand and cool to 24 ° C.

[0040] S2. Ultrafiltration of the solution through a 0.45 μm aqueous ultrafiltration membrane to obtain a filtrate, and concentration of the filtrate at 80° C. for 12 h to obtain carbon quantum dots of genkwa powder and carbon quantum dots of genkwa residue powder, respectively.

[0041] Among them, the carbon quantum dots from genus aralia powder are denoted as Y120 / 6, and the carbon quantum dots from genus aralia slag powder are denoted as Z120 / 6.

[0042] Example 2

[0043] A method for preparing carbon quantum dots from radix quinquefolii, comprising the following steps:

[0044] S1. Take 1 g of genkwa root powder and 1 g of genkwa root residue powder, add 60 mL of distilled water respectively, stir magnetically for 10 min, then transfer to a high-pressure reactor, place it at 120 ° C for hydrothermal reaction for 12 h, filter and discard the sediment to obtain a solution, and let the solution stand and cool to 20 ° C.

[0045] S2. The solution was ultrafiltered through a 0.45 μm aqueous ultrafiltration membrane to obtain a filtrate. The filtrate was concentrated at 80° C. for 12 h to obtain carbon quantum dots from genus dahurica powder and carbon quantum dots from genus dahurica residue powder, respectively.

[0046] Among them, the carbon quantum dots from genus aralia powder are recorded as Y120 / 12, and the carbon quantum dots from genus aralia slag powder are recorded as Z120 / 12.

[0047] Example 3

[0048] A method for preparing carbon quantum dots from radix quinquefolii, comprising the following steps:

[0049] S1. Take 1 g of genkwa root powder and 1 g of genkwa root residue powder, add 60 mL of distilled water respectively, stir magnetically for 10 min, then transfer to a high-pressure reactor, place it at 160 ° C for hydrothermal reaction for 6 h, filter and discard the sediment to obtain a solution, and let the solution stand and cool to 23 ° C.

[0050] S2. The solution was ultrafiltered through a 0.45 μm aqueous ultrafiltration membrane to obtain a filtrate. The filtrate was concentrated at 80° C. for 12 h to obtain carbon quantum dots from genus dahurica powder and carbon quantum dots from genus dahurica residue powder, respectively.

[0051] Among them, the carbon quantum dots from genus arborvitae powder are denoted as Y160 / 6, and the carbon quantum dots from genus arborvitae slag powder are denoted as Z160 / 6.

[0052] Example 4

[0053] A method for preparing carbon quantum dots from radix quinquefolii, comprising the following steps:

[0054] S1. Take 1 g of genkwa root powder and 1 g of genkwa root residue powder, add them into 60 mL of distilled water respectively, stir magnetically for 10 min, then transfer to a high-pressure reactor, place at 160 ° C, hydrothermally react for 12 h, filter and discard the sediment to obtain a solution, and let the solution stand to cool to 22 ° C.

[0055] S2. The solution was ultrafiltered through a 0.45 μm aqueous ultrafiltration membrane to obtain a filtrate. The filtrate was concentrated at 80° C. for 12 h to obtain carbon quantum dots from genus dahurica powder and carbon quantum dots from genus dahurica residue powder, respectively.

[0056] Among them, the carbon quantum dots from genus aralia powder are denoted as Y160 / 12, and the carbon quantum dots from genus aralia slag powder are denoted as Z160 / 12.

[0057] Example 5

[0058] A method for preparing carbon quantum dots from radix quinquefolii, comprising the following steps:

[0059] S1. Take 1 g of genus corydalis powder and 1 g of genus corydalis residue powder, add them into 60 mL of distilled water respectively, stir magnetically for 10 min, then transfer them into a high-pressure reactor, place them at 200 ° C, and hydrothermally react for 6 h. Filter and discard the sediment to obtain a solution, and let the solution stand and cool to 24 ° C.

[0060] S2. The solution was ultrafiltered through a 0.45 μm aqueous ultrafiltration membrane to obtain a filtrate. The filtrate was concentrated at 80° C. for 12 h to obtain carbon quantum dots from genus dahurica powder and carbon quantum dots from genus dahurica residue powder, respectively.

[0061] Among them, the carbon quantum dots from genus arborvitae powder are denoted as Y200 / 6, and the carbon quantum dots from genus arborvitae slag powder are denoted as Z200 / 6.

[0062] Example 6

[0063] A method for preparing carbon quantum dots from radix quinquefolii, comprising the following steps:

[0064] S1. Take 1 g of genus corydalis powder and 1 g of genus corydalis residue powder, add them into 60 mL of distilled water respectively, stir magnetically for 10 min, then transfer them into a high-pressure reactor, place them at 200 ° C, and hydrothermally react for 12 h. Filter and discard the sediment to obtain a solution, and let the solution stand and cool to 20 ° C.

[0065] S2. The solution was ultrafiltered through a 0.45 μm aqueous ultrafiltration membrane to obtain a filtrate. The filtrate was concentrated at 80° C. for 12 h to obtain carbon quantum dots from genus dahurica powder and carbon quantum dots from genus dahurica residue powder, respectively.

[0066] Among them, the carbon quantum dots from genus arborvitae powder are denoted as Y200 / 12, and the carbon quantum dots from genus arborvitae residue powder are denoted as Z200 / 12.

[0067] The carbon quantum dots of genkwa powder and genkwa residue powder in Examples 1 to 6 were characterized by infrared spectroscopy. Figure 1 As shown. Figure 1 It can be seen that the Fourier transform infrared spectra of carbon quantum dots from genus radix powder and genus radix residue powder are at 3390 cm -1 The peaks near 2939cm show OH / NH stretching vibration, indicating the presence of hydroxyl and amine groups in the series of carbon quantum dots. -1 、1624cm -1 、1413cm -1 、1249cm -1 1083cm -1 The peaks at are attributed to CH, C=O, CN, COC and CO stretching vibrations, respectively.

[0068] 1. Study on the activity of inhibiting bacteria

[0069] 1) Bacterial inhibition

[0070] Staphylococcus aureus and Escherichia coli were selected as representatives of Gram-positive and Gram-negative bacteria, respectively.

[0071] The carbon quantum dots of genus daphne powder and genus daphne residue powder prepared in Examples 1 to 6 were mixed with water to prepare carbon dot solutions with different concentrations of 3.125 mg / L, 6.25 mg / L and 12.5 mg / L, and then respectively incubated with Staphylococcus aureus and Escherichia coli, wherein the concentrations of Staphylococcus aureus and Escherichia coli were both 1×10 6 CFU / mL, after mixing the carbon dot solution and bacterial solution in a volume ratio of 1:1, co-culture at 37℃ for 12 hours to obtain the culture solution; then inoculate 50μL of the culture solution into the agar medium and culture at 37℃ for 24 hours to observe the results, such as Figures 2 to 5 As shown. Figures 2 to 5 It can be seen that all six genus scutellaria carbon dots and six genus slag carbon dots exhibited inhibitory activity against E. coli and Staphylococcus aureus. The higher the temperature and the longer the hydrothermal reaction time, the better the antibacterial effect. The inhibition was also related to the concentration of the carbon dots solution, with higher concentrations indicating a more pronounced inhibitory effect. Overall, genus scutellaria carbon dots exhibited greater inhibitory activity against E. coli, while genus scutellaria carbon dots exhibited greater inhibitory activity against Staphylococcus aureus.

[0072] 2) Fungal inhibition

[0073] Penicillium expansum was selected as a representative of plant pathogenic fungi, and the genus dung carbon dots Z200 / 12 and genus dung carbon dots Y200 / 12 with good antibacterial effects were selected as examples. They were respectively prepared into carbon dot solutions with a concentration of 60 mg / mL. 15 mL of the two carbon dot solutions were taken and added to 135 mL of PDA culture medium cooled to 60 ° C. The final concentration of the two carbon dot solutions was 6 mg / mL. After mixing thoroughly, pour it into the culture dish. After the culture medium solidified, a pathogenic fungus cake was inoculated into the center of each culture dish, and it was cultured at 25 ° C to observe the mycelium diameter. Each treatment was repeated 3 times, and the control group without carbon dot solution was recorded as CK. The results are shown in the figure. Figure 6As shown in the figure, both genus genus carbon quantum dots and genus genus residue carbon quantum dots have an inhibitory effect on Penicillium expansum. Under the same synthesis conditions and concentrations, genus genus residue carbon quantum dots exhibit stronger inhibitory ability than genus genus carbon quantum dots. This may be due to the different functional groups on the surfaces of the two carbon quantum dots, resulting in different inhibitory abilities. By comparing the Fourier transform infrared spectra of genus genus residue carbon dots Z 200 / 12 and genus genus residue carbon dots Y200 / 12, it can be found that the C=O peak intensity of genus genus residue carbon dots Z 200 / 12 is higher than that of genus genus residue carbon dots Y200 / 12. The presence of C=O has a positive impact on the antibacterial effect. The carbonyl group has high reactivity and can react with biomacromolecules in microbial cells, such as proteins and nucleic acids, to interfere with the normal metabolism and physiological functions of microorganisms, thereby producing antibacterial or bactericidal effects.

[0074] Select the best antibacterial effect of genus dregs carbon quantum Z200 / 12, prepare the concentration of 100mg / mL and 10mg / mL carbon dot solution, take 5mL of the above two concentrations of carbon dot solution and add them to 100mL PDA culture medium cooled to 60℃, the final concentration of the two concentrations of carbon dot solution is 4.76mg / mL and 0.48mg / mL respectively. After mixing thoroughly, pour into the culture dish, wait for the culture medium to solidify, inoculate a pathogenic fungus cake in the center of each culture dish, place it at 25℃, observe the mycelium diameter, the results are as follows Figure 7 As shown, it can be seen that the carbon quantum dots from the root of genus Dahurica show a strong inhibitory ability on Penicillium expansum. The higher the content of carbon quantum dots in the culture medium, the better the inhibitory effect on the growth of Penicillium expansum hyphae. When the concentration is as low as 0.48 mg / mL, it still has an inhibitory effect.

[0075] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0076] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A broad-spectrum antibacterial carbon quantum dot, characterized in that The broad-spectrum antibacterial carbon quantum dots are obtained by subjecting genkwa powder or genkwa residue to a hydrothermal reaction in an aqueous environment, filtering and discarding the sediment, and concentrating. The temperature of the hydrothermal reaction is 120°C to 200°C, and the time is 6h to 8h; The mass volume ratio of the genus dahurica powder or genus dahurica residue to water is 1g-1.2g:60mL; The genus dahurica residue is obtained by ultrasonic-assisted water extraction of polysaccharides.

2. The broad-spectrum antibacterial carbon quantum dots according to claim 1, characterized in that The specific method of obtaining the genus velvet residue is as follows: Mixing the genus Dahuricae with water, extracting under ultrasonic conditions at 60° C. to 65° C. for 50 to 55 minutes, filtering, drying, and crushing the precipitate to obtain the genus Dahuricae residue; The power of the ultrasound is 350W to 360W.

3. A method for preparing broad-spectrum antibacterial carbon quantum dots according to any one of claims 1 or 2, characterized in that: The following steps are included: The genus dahurica powder or genus dahurica residue is mixed with water, and a hydrothermal reaction is carried out at 120°C to 200°C for 6h to 8h. The sediment is filtered and discarded to obtain a solution. The solution is allowed to stand and cool to 20°C to 24°C. The solution is filtered through a filter membrane to obtain a filtrate. The filtrate is concentrated to obtain the broad-spectrum antibacterial carbon quantum dots.

4. The method for preparing broad-spectrum antibacterial carbon quantum dots according to claim 3, wherein: The filter membrane is a 0.45 μm water ultrafiltration membrane.

5. Use of the broad-spectrum antibacterial carbon quantum dots according to any one of claims 1 or 2 in the preparation of antifungal products.

6. The use according to claim 5, characterized in that The fungus is Penicillium expansum.

7. Use of the broad-spectrum antibacterial carbon quantum dots according to any one of claims 1 or 2 in the preparation of antibacterial products.

8. The use according to claim 7, characterized in that The bacteria are one or both of Escherichia coli and Staphylococcus aureus.

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