Peanut shell-based carbon dots with antioxidant and antibacterial functions and application of peanut shell-based carbon dots

Abstract

The invention relates to peanut shell-based carbon dots with antioxidant and antibacterial functions and a preparation method of the peanut shell-based carbon dots, and belongs to the technical field of preparation and application of biomass nanomaterials. According to the method, dried and smashed peanut shells are prepared into the carbon dots through a one-step hydrothermal method, the surfaces of the peanut shell-based carbon dots are rich in a large number of phenolic light groups, alcohol functional groups, aldehyde functional groups and other structures, so that the carbon dots have high oxidation resistance, meanwhile, the antibacterial activity of the carbon dots is excellent, and the carbon dots have a good antibacterial effect on staphylococcus aureus and escherichia coli. The manufacturing process is simple, processing wastes are reused, and the method is green and environment-friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and in particular relates to peanut shell-based carbon dots with both antioxidant and antibacterial functions and applications thereof. Background Art

[0002] Carbon dots (CDs) are a novel class of zero-dimensional carbon nanomaterials composed of discrete, quasi-spherical nanoparticles with diameters less than 10 nm. CDs exhibit excellent photoluminescence, antibacterial, antioxidant, and biocompatibility properties, and hold great promise for applications in bioimaging, biosensing, adulteration detection, and food testing.

[0003] At present, the preparation of CDs is mainly divided into two approaches: "top-down" and "bottom-up". Among them, "top-down" is usually achieved by methods such as arc discharge, laser etching, electrochemical oxidation, and acidic stripping, and "bottom-up" includes hydrothermal / solvothermal method, microwave method, template method, etc. Among them, the hydrothermal method is economical, convenient, safe, and efficient, and the prepared CDs have uniform particle size, which is deeply favored by researchers. It is worth noting that this method can optimize the performance of CDs by adjusting the reaction conditions, so as to better put them into practical applications. The raw materials for synthesizing CDs are widely available. Renewable natural products can be selected as precursors and combined with hydrothermal methods to try to prepare green CDs with high antioxidant and antibacterial functions.

[0004] Peanut shells, a byproduct of peanut production, are often considered agricultural waste, resulting in both resource waste and environmental pollution. Peanut shells, primarily composed of organic substances such as cellulose, hemicellulose, and lignin, possess considerable economic value and diverse uses. Furthermore, peanut shells are not only a rich carbon source but also contain a variety of flavonoids. Studies have shown that these flavonoids exhibit diverse biological activities, including anti-inflammatory, antibacterial, and antioxidant activities. This suggests the feasibility of using peanut shells as a synthetic precursor to prepare CDs with both antioxidant and antibacterial properties via a one-step hydrothermal method.

[0005] CN118909623A discloses a method for preparing a biomass carbon dot corrosion inhibitor, comprising the following steps: washing peanut shells, drying them naturally, crushing them, and sieving them; placing them in a 1-5% NaOH solution after sieving and reacting them for 3-8 hours; filtering and rinsing them to neutrality after the reaction is completed; drying the treated peanut shells and placing them in a 1-5% NaClO2 solution, adjusting the pH of the solution to acidity with acetic acid, and reacting them for 3-5 hours; filtering and rinsing them to neutrality after the reaction is completed to obtain peanut shell cellulose; sealing the peanut shell cellulose and deionized water in a polytetrafluoroethylene-lined stainless steel autoclave, heating them for 10-14 hours, cooling them naturally to room temperature, and centrifuging them for 8-12 minutes, filtering to remove residual large particles, and then adding 10-30 mL of 0-200 mg / L CaCl2. 2+ The mixture is stirred evenly, and then subjected to rotary evaporation and vacuum freeze drying to obtain a solid biomass carbon dot CDs powder. Although the invention discloses a method for preparing a solid biomass carbon dot CDs powder using peanut shells, the preparation process of the invention requires the use of a large amount of chemical reagents, which cannot meet the requirements of environmental protection.

[0006] CN118908603A discloses a carbon dot-based titanium dioxide nanocomposite material. Its preparation method includes the following steps: S1. Cleaning peanut shell humus, drying it, and crushing it to obtain peanut shell powder for later use; S2. Placing the peanut shell powder in a hydrothermal reactor to react and obtain a hydrothermal mixed solution; S3. Filtering the hydrothermal mixed solution, removing the supernatant and freeze-drying it to obtain biomass carbon dots. Although this invention discloses a method for preparing carbon dots using peanut shell humus, it is unknown whether the biomass carbon dots produced thereby possess both antioxidant and antibacterial properties.

[0007] Although there are many reports on the preparation of carbon dot antibacterial and antioxidant agents using other fruit shells (such as lychee shells used in CN118125421A and walnut shells in CN118561269A) as the main raw materials, the preparation of peanut shell-based carbon dots with good antioxidant and antibacterial effects using peanut shells as the main raw material remains a technical problem that needs to be solved. Summary of the Invention

[0008] To overcome at least one of the problems with the existing technology, the present invention provides peanut shell-based carbon dots with both antioxidant and antibacterial properties and their applications. This method primarily uses dried peanut shells as a carbon source and prepares the carbon dots via a one-step hydrothermal process. The simple production process reuses agricultural processing waste, avoiding the waste of natural resources.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a peanut shell-based carbon dot having both antioxidant and antibacterial functions, which is prepared by the following method:

[0011] 1) washing, drying, crushing, and sieving the peanut shell raw material to obtain peanut shell powder;

[0012] 2) uniformly mixing the peanut shell powder prepared in step 1) with ultrapure water to obtain a peanut shell suspension;

[0013] 3) subjecting the peanut shell suspension prepared in step 2) to a hydrothermal reaction, centrifuging and filtering after the reaction, and collecting the supernatant to obtain a peanut shell-based carbon dot solution;

[0014] 4) The peanut shell-based carbon dot solution prepared in step 3) is filtered, dialyzed, and dried to obtain the peanut shell-based carbon dots having both antioxidant and antibacterial functions.

[0015] Furthermore, the sieve used in the step 1) is 80 mesh.

[0016] Furthermore, in step 2), the sieved peanut shell powder is dispersed in a container filled with ultrapure water, stirred and ultrasonically mixed for 20 minutes to mix evenly.

[0017] Furthermore, in step 2), the mass volume ratio of peanut shell powder to ultrapure water is 1 g: (20-25) mL.

[0018] Preferably, in step 2), the mass volume ratio of peanut shell powder to ultrapure water is 1 g:25 mL.

[0019] Furthermore, the reaction temperature of the hydrothermal reaction in step 3) is 180-200°C.

[0020] Furthermore, the reaction time of the hydrothermal reaction in step 3) is 8-12 hours.

[0021] Preferably, the reaction conditions of the hydrothermal reaction in step 3) are: performing the hydrothermal reaction at 180° C. for 8 hours.

[0022] Furthermore, in step 3), the centrifugation condition is to use a centrifugal force of 10,000 g for 15 minutes.

[0023] Furthermore, the filtration and dialysis conditions in step 4) are: dialysis for 48-51 hours after passing through a 0.22 μm filter membrane, and changing the water every 6-8 hours.

[0024] Furthermore, the drying in step 4) is carried out in a low-temperature freeze dryer for 48 hours.

[0025] In a second aspect, the peanut shell-based carbon dots provided in the first aspect of the present invention are used in the preparation of a bactericidal additive.

[0026] Furthermore, the peanut shell-based carbon dots of the present invention are used in the preparation of additives for inhibiting the growth of Escherichia coli and Staphylococcus aureus.

[0027] In a third aspect, the peanut shell-based carbon dots provided in the first aspect of the present invention are used in the preparation of antioxidant additives.

[0028] Compared with the prior art, the present invention adopts the above technical solution to achieve the following beneficial effects:

[0029] 1) The present invention adopts a simple method such as a one-step hydrothermal reaction method and a separation and impurity removal method to prepare a peanut shell-based carbon dot with both antioxidant and antibacterial functions. Not only is the raw material cost low, but the preparation method is also green and environmentally friendly and easy to operate.

[0030] 2) The peanut shell-based carbon dots prepared by the method of the present invention have good antioxidant activity, especially excellent scavenging effect on DPPH free radicals.

[0031] 3) The peanut shell-based carbon dot antibacterial agent prepared by the method of the present invention has a broad-spectrum antibacterial effect, and is very effective against Staphylococcus aureus. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The yield of carbon dots prepared with different amounts of peanut shell powder added under the same reaction time and temperature;

[0033] Figure 2 The yield of carbon dots prepared at different reaction temperatures for the same reaction time and the same amount of peanut shell powder added;

[0034] Figure 3 The yield of carbon dots prepared at different reaction times at the same reaction temperature and the same amount of peanut shell powder added;

[0035] Figure 4 This is a TEM electron microscope image of the peanut shell-based carbon dots described in Example 4;

[0036] Figure 5 This is the particle size distribution diagram of peanut shell-based carbon dots described in Example 4;

[0037] Figure 6 This is the X-ray diffraction pattern of the peanut shell-based carbon dots described in Example 4;

[0038] Figure 7 This is the XPS spectrum of the peanut shell-based carbon dots described in Example 4;

[0039] Figure 8 This is the infrared spectrum of the peanut shell-based carbon dots described in Example 4;

[0040] Figure 9 This is the UV-visible spectrum of the peanut shell-based carbon dots described in Example 4;

[0041] Figure 10 is the scavenging rate of ABTS free radicals by the peanut shell-based carbon dots described in Example 4;

[0042] Figure 11 is the scavenging rate of DPPH free radicals by the peanut shell-based carbon dots described in Example 4;

[0043] Figure 12 The growth diagram of Staphylococcus aureus and Escherichia coli under the peanut shell-based carbon dots described in Example 4 under different lighting conditions. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. The experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national standards. The experimental materials in the following examples where the sources are not specified are all commercially available raw materials. The equipment used in each step of the following examples is conventional equipment. If there are no corresponding national standards, the steps are carried out in accordance with general international standards, conventional conditions, or conditions recommended by the manufacturer. Unless otherwise specified, all parts are by weight and all percentages are by mass percentages. Unless otherwise defined or specified, all professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention.

[0045] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention.

[0046] The present invention provides a peanut shell-based carbon dot with both antioxidant and antibacterial functions, which is prepared by the following method:

[0047] 1) washing, drying, crushing, and sieving the peanut shell raw material to obtain peanut shell powder;

[0048] 2) uniformly mixing the peanut shell powder prepared in step 1) with ultrapure water to obtain a peanut shell suspension;

[0049] 3) subjecting the peanut shell suspension prepared in step 2) to a hydrothermal reaction, centrifuging and filtering after the reaction, and collecting the supernatant to obtain a peanut shell-based carbon dot solution;

[0050] 4) The peanut shell-based carbon dot solution prepared in step 3) is filtered, dialyzed, and dried to obtain the peanut shell-based carbon dots having both antioxidant and antibacterial functions.

[0051] Furthermore, the sieve used in the step 1) is 80 mesh.

[0052] Furthermore, in step 2), the sieved peanut shell powder is dispersed in a container filled with ultrapure water, stirred and ultrasonically mixed for 20 minutes to mix evenly.

[0053] Furthermore, in step 2), the mass volume ratio of peanut shell powder to ultrapure water is 1 g: (20-25) mL.

[0054] Preferably, in step 2), the mass volume ratio of peanut shell powder to ultrapure water is 1 g:25 mL.

[0055] Furthermore, the reaction temperature of the hydrothermal reaction in step 3) is 180-200°C.

[0056] Furthermore, the reaction time of the hydrothermal reaction in step 3) is 8-12 hours.

[0057] Preferably, the reaction conditions of the hydrothermal reaction in step 3) are: performing the hydrothermal reaction at 180° C. for 8 hours.

[0058] Furthermore, in step 3), the centrifugation condition is to use a centrifugal force of 10,000 g for 15 minutes.

[0059] Furthermore, the filtration and dialysis conditions in step 4) are: dialysis for 48-51 hours after passing through a 0.22 μm filter membrane, and changing the water every 6-8 hours.

[0060] Furthermore, the drying in step 4) is carried out in a low-temperature freeze dryer for 48 hours.

[0061] Specific examples are as follows.

[0062] Example 1

[0063] This embodiment relates to the preparation of peanut shell-based carbon dots, which includes the following steps:

[0064] Peanut shells were first washed with deionized water and then oven-dried at 60°C for 24 hours. The dried peanut shells were then pulverized and sieved through an 80-mesh sieve. Different weights of peanut shell powder (0.5, 1.0, 1.5, 2, and 2.5 g) were weighed and added to 25 mL of ultrapure water. The mixture was stirred for 20 minutes and then sonicated for 30 minutes. After thorough mixing, the mixture was added to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 180°C for 8 hours. After cooling to room temperature, the reaction solution was centrifuged at 10,000 g for 15 minutes. The supernatant was filtered through a 0.22 μm microporous membrane and dialyzed using a 1000 Da dialysis bag at 4°C for 48 hours. The dialyzed product was freeze-dried in a vacuum evaporation chamber to obtain peanut shell-based carbon dots for future use.

[0065] Example 2

[0066] Peanut shells were first washed with deionized water and then oven-dried at 60°C for 24 hours. The dried peanut shells were then pulverized and sieved through an 80-mesh screen. 1.0 g of peanut shell powder was weighed and dissolved in 25 mL of ultrapure water. The mixture was stirred for 20 minutes and then sonicated for 30 minutes. After thorough mixing, the mixture was added to a 50 mL polytetrafluoroethylene-lined reactor and reacted for 8 hours at different temperatures (160°C, 170°C, 180°C, 190°C, and 200°C). After cooling to room temperature, the reaction solution was centrifuged at 10,000 g for 15 minutes. The supernatant was filtered through a 0.22 μm microporous membrane and dialyzed using a 1000 Da dialysis bag at 4°C for 48 hours. The dialyzed product was freeze-dried in a vacuum evaporation chamber to obtain peanut shell-based carbon dots for future use.

[0067] Example 3

[0068] Peanut shells were first washed with deionized water and then oven-dried at 60°C for 24 hours. The dried peanut shells were then pulverized and sieved through an 80-mesh screen. 1.0 g of peanut shell powder was weighed and added to 25 mL of ultrapure water. The mixture was stirred for 20 minutes and then sonicated for 30 minutes. After thorough mixing, the mixture was added to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 180°C for different times (2, 4, 6, 8, and 10 hours). After cooling to room temperature, the reaction solution was centrifuged at 10,000 g for 15 minutes. The supernatant was filtered through a 0.22 μm microporous membrane and dialyzed using a 1000 Da dialysis bag at 4°C for 48 hours. The dialyzed product was freeze-dried in a vacuum evaporation chamber to obtain peanut shell-based carbon dots for later use.

[0069] Summary 1

[0070] The yields of the peanut shell-based carbon dots prepared in Example 1, Example 2 and Example 3 were calculated respectively.

[0071] like Figure 1 As shown in the figure, under the same reaction time and temperature, the yield of peanut shell-based carbon dots prepared varies with the addition amount of peanut shell powder. The highest yield of peanut shell-based carbon dots is reached for the first time when the addition amount of peanut shell powder is 40 mg / mL (1 g). Thereafter, there is no significant increase in yield as the addition amount of peanut shell powder increases.

[0072] like Figure 2 As shown in the figure, at the same reaction time and the same amount of peanut shell powder added, the yield of peanut shell-based carbon dots prepared at different reaction temperatures also varies. The yield increases with increasing reaction temperature and reaches the highest value at 180°C.

[0073] like Figure 3 As shown in the figure, at the same reaction temperature and the same amount of peanut shell powder added, the yield of peanut shell-based carbon dots prepared at different reaction times is also different. The yield increases with the increase of reaction time, reaching the highest value for the first time at 8 hours. Subsequently, the yield does not increase significantly with the increase of time, and even decreases after 10 hours.

[0074] According to the yield analysis of the peanut shell-based carbon dots in Example 1, Example 2 and Example 3, the optimal reaction conditions were selected: a reaction time of 8 h, a reaction temperature of 180° C., and an addition amount of peanut shell powder of 40 mg / mL.

[0075] Example 4

[0076] First, the peanut shells were washed with deionized water and then dried in an oven at 60°C for 24 hours. The dried peanut shells were then pulverized and sieved through an 80-mesh screen. 1.0 g of peanut shell powder was weighed and added to 25 mL of ultrapure water. The mixture was stirred for 20 minutes and then sonicated for 30 minutes. After thorough mixing, the mixture was added to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 180°C for 8 hours. After cooling to room temperature, the reaction solution was centrifuged at 10,000 g for 15 minutes. The supernatant was filtered through a 0.22 μm microporous membrane and dialyzed using a 1000 Da dialysis bag at 4°C for 48 hours. The dialyzed product was freeze-dried in a vacuum evaporation chamber to obtain peanut shell-based carbon dots for future use.

[0077] Carbon dot characterization

[0078] The peanut shell-based carbon dots obtained in Example 4 were characterized and identified by TEM electron microscopy, particle size, XRD, UV spectroscopy, IR spectroscopy, XPS, etc. The specific results are shown in Figure 4-Figure 9 .

[0079] Figure 4The following are the results of TEM imaging and analysis. At a resolution of 20 nm, the synthesized carbon dots are observed to have a spherical structure and are evenly dispersed with varying particle sizes. Furthermore, at a resolution of 2 nm, the microstructure of individual carbon dots is revealed, with a lattice spacing of 0.22 nm. This is consistent with the morphology of carbon dots reported in the literature.

[0080] Figure 5 The particle size analysis results of peanut shell-based carbon dots are shown in Figure 2. As can be seen from the figure, the particle size of the carbon dots prepared in this experiment ranges from 0.8nm to 3nm, with an average particle size of 2.00±0.41nm. The overall particle size distribution is uniform, which is consistent with the morphological characteristics of carbon dots.

[0081] Figure 6 The XRD spectrum of peanut shell-based carbon dots shows a distinct broad diffraction peak at 20.2°, which is consistent with the (002) plane of graphitic carbon. This indicates that the center of the peanut shell-based carbon dots contains a highly carbonized graphene structure, which is consistent with the TEM results of peanut shell-based carbon dots.

[0082] Figure 7 Figure a shows three characteristic peaks, the peaks at 285.7, 400.1 and 532.8 eV correspond to C1s, N1s and O1s, respectively, indicating that the peanut shell-based carbon dots are composed of three elements: C (64.80%), O (29.66%) and N (5.54%); in Figure b, the high-resolution spectrum of C1s has three peaks at 284.8, 286.3 and 288.2 eV corresponding to C=C / CC, CO / CN and C=O / O=CO, respectively; in Figure c, the high-resolution spectrum of N1s shows three peaks at about 398.8, 399.9 and 401.2 eV, representing pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen, respectively; in Figure d, the high-resolution spectrum of O1s shows two peaks at about 533 and 531.7 eV, representing C=O and C—O, respectively.

[0083] Figure 8 This is the infrared spectrum of peanut shell-based carbon dots. Peanut shell-based carbon dots have an infrared spectrum of 669.2 cm -1 The out-of-plane bending vibration peaks of NH appeared at 1234.5 and 1079 cm -1 The absorption peaks at 1419 cm-1 are the symmetric and asymmetric stretching vibrations of COC. -1 is the stretching vibration peak of C=C, 1594cm -1 is the stretching vibration peak of C=O; 2967cm -1 The stretching vibration peak of CH appeared at 3382 cm -1These results indicate that the peanut shell-based carbon dots contain hydrophilic groups such as hydroxyl (-COOH), carboxyl (-OH), and imine (-NH-) groups on their surface, indicating that the peanut shell-based carbon dots have good water solubility.

[0084] Figure 9 This is the UV-visible spectrum of peanut shell-based carbon dots. Peanut shell-based carbon dots have a maximum UV absorption peak at 280.5nm. This is believed to be caused by the π-π* electron transition on the C=C bond and the n-π* transition on the C=O bond contained in the carbon dots, indicating that the carbon dot structure has sp 2 Carbon structure.

[0085] These results confirm the presence of hydroxyl, carbonyl and carboxyl groups in peanut shell-based carbon dots, which endows them with good water solubility, which is consistent with the infrared spectrum results of peanut shell-based carbon dots.

[0086] Antioxidant capacity analysis

[0087] The antioxidant capacity of the peanut shell-based carbon dots described in Example 4 was analyzed, including DPPH scavenging rate and ABTS scavenging rate. The results are as follows: Figure 10 and Figure 11 shown.

[0088] The specific steps include:

[0089] 1 mL of a 0.1 mM DPPH ethanol solution was mixed with 1 mL of peanut shell-based carbon dots at varying concentrations (1 to 512 μg / mL). After 20 minutes of reaction in the dark, the absorbance at 517 nm was measured. The DPPH radical scavenging capacity of the peanut shell-based carbon dots was calculated using the following formula:

[0090]

[0091] Wherein, Ai represents the absorbance of DPPH ethanol solution after reaction with peanut shell-based carbon dots, and A0 represents the absorbance of DPPH ethanol solution.

[0092] Mix 7 mmol / L ABTS reagent with an equal volume of 2.45 mmol potassium persulfate solution to form an ABTS mother solution. React at 4°C in the dark for 12 to 16 hours and set aside. Dilute the ABTS mother solution with deionized water until the absorbance at 734 nm reaches 0.7 ± 0.02 to obtain the ABTS working solution. Take 0.1 mL of samples of different concentrations (1 to 512 μg / mL) and add 3 mL of ABTS working solution to mix. React in the dark for 6 minutes and measure the absorbance at 734 nm. The proportion of peanut shell-based carbon dots scavenging ABTS free radicals is calculated according to the following formula:

[0093]

[0094] Where Ai represents the absorbance of the ABTS solution after reaction with peanut shell-based carbon dots,

[0095] A0 represents the absorbance of the ABTS solution after adding an equal volume of distilled water.

[0096] When the peanut shell-based carbon dots concentration increased from 0 μg / mL to 512 μg / mL, the absorption intensities of DPPH radicals at 517 nm and ABTS radicals at 734 nm both showed a decreasing trend, indicating that the carbon dots' scavenging abilities for DPPH and ABTS radicals were dose-dependent. As the peanut shell-based carbon dots concentration increased from 8 μg / mL to 512 μg / mL, the scavenging efficiency of the peanut shell-based carbon dots for DPPH radicals increased from 16.29% to 99.89%, and for ABTS radicals from 23.05% to 99.99%.

[0097] Based on the above antioxidant experiments, it can be inferred that the peanut shell-based carbon dots described in Example 4 may contain phenolic groups and alcohol or aldehyde reducing groups, which is consistent with the conclusions of FT-IR spectroscopy and XPS characterization analysis.

[0098] Antibacterial activity assay

[0099] The antibacterial activity of the peanut shell-based carbon dots described in Example 4 was determined:

[0100] The bacterial antibacterial assay uses Escherichia coli as a Gram-negative bacteria model and Staphylococcus aureus as a Gram-positive bacteria model using the dilution spread plate method. The specific protocol is as follows:

[0101] Escherichia coli and Staphylococcus aureus in glycerol were inoculated into LB broth and cultured at 37°C for 12 h. The bacterial suspension was then diluted to 10 5 -10 6 CFU / mL;

[0102] The above bacterial suspension was mixed with a 0.5 mg / mL peanut shell-based carbon dot solution in a volume ratio of 1:1 by oscillation, and incubated in the dark and light for 1 h, respectively. After the agar medium solidified, the incubated bacterial liquid was inoculated on the agar medium. After incubation in a 37°C incubator for 16 h, the growth of the colonies in the culture medium was observed and photographed.

[0103] The results of the bacterial antibacterial test on the 0.5 mg / mL peanut shell-based carbon dots prepared in Example 4 are as follows: Figure 12As shown in the figure, it can be seen that peanut shell-based carbon dots can inhibit the growth of Escherichia coli and Staphylococcus aureus under dark conditions, but the antibacterial effect is weak; in an environment illuminated by LED light, since peanut shell-based carbon dots can act as nanozymes to promote the generation of reactive oxygen species (ROS), thereby oxidizing the bacterial cell membrane lipids and damaging the proteins and DNA in their cells, the inhibitory effect on these two bacteria is more significant, almost completely stopping their growth.

[0104] While the specific embodiments of the present invention have been described in detail above, these are intended to be exemplary only, and the present invention is not limited thereto. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, any equivalent changes and modifications made without departing from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A peanut shell-based carbon dot with both antioxidant and antibacterial functions, characterized in that: Prepared by the following method: 1) washing, drying, crushing, and sieving the peanut shell raw material to obtain peanut shell powder; 2) uniformly mixing the peanut shell powder prepared in step 1) with ultrapure water to obtain a peanut shell suspension; 3) subjecting the peanut shell suspension prepared in step 2) to a hydrothermal reaction, centrifuging and filtering after the reaction, and collecting the supernatant to obtain a peanut shell-based carbon dot solution; 4) The peanut shell-based carbon dot solution prepared in step 3) is filtered, dialyzed, and dried to obtain the peanut shell-based carbon dots having both antioxidant and antibacterial functions.

2. The peanut shell-based carbon dots according to claim 1, characterized in that In the step 2), the mass volume ratio of peanut shell powder to ultrapure water is 1 g: (20-25) mL.

3. The peanut shell-based carbon dots according to claim 1, characterized in that The reaction temperature of the hydrothermal reaction in step 3) is 180-200°C.

4. The peanut shell-based carbon dots according to claim 1, characterized in that The reaction time of the hydrothermal reaction in step 3) is 8-12 hours.

5. The peanut shell-based carbon dots according to claim 1, characterized in that In the step 2), the mass volume ratio of peanut shell powder to ultrapure water is 1 g:25 mL.

6. The peanut shell-based carbon dots according to any one of claims 3 or 4, characterized in that The reaction conditions of the hydrothermal reaction in step 3) are: performing the hydrothermal reaction at 180° C. for 8 hours.

7. The peanut shell-based carbon dots according to claim 1, characterized in that The sieve used in step 1) of the preparation method is 80 mesh.

8. The peanut shell-based carbon dots according to claim 1, characterized in that The filtration and dialysis conditions in step 4) are as follows: dialysis for 48-51 hours after passing through a 0.22 μm filter membrane, with water being changed every 6-8 hours.

9. Use of the peanut shell-based carbon dots according to any one of claims 1 to 8 in the preparation of a bactericidal additive.

10. Use of the peanut shell-based carbon dots according to any one of claims 1 to 8 in the preparation of antioxidant additives.

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