Preparation method and application of antibacterial red light dual-emission carbon quantum dots based on sodium ion doping

Abstract

The invention provides a preparation method and application of antibacterial red light dual-emission carbon quantum dots based on sodium ion doping. According to the invention, 3, 4-diaminobenzene sulfonic acid is taken as a carbon source, sodium dihydrogen phosphate is taken as an auxiliary additive, deionized water is taken as a solvent, and high-temperature and high-pressure hydrothermal reaction is adopted for synthesis. The selected precursor reaction raw materials are non-toxic and harmless non-hazardous chemicals, the preparation process is green and environment-friendly, the obtained red-light fluorescent carbon quantum dot product solution is relatively pure, and the synthesis, cleaning and purification steps are simple and convenient. In terms of performance, the obtained carbon quantum dot has a non-excitation-dependent dual-emission fluorescence characteristic in a red light band, the material has good antibacterial property, and a new strategy is provided for application of the carbon quantum dot in multiple aspects of deep tissue penetration imaging, antibacterial treatment, ratio fluorescence sensing, photoelectric devices and the like.

Description

Technical Field

[0001] This invention belongs to the field of antibacterial nanomaterials technology, and relates to the preparation and application of carbon-based quantum dot materials, specifically to a method for preparing and applying antibacterial red-light carbon quantum dots based on sodium ion doping. Background Technology

[0002] The advent of antibiotics has alleviated the suffering of countless people and saved countless lives. However, due to the development of drug resistance, antibiotics are gradually losing their effectiveness. Therefore, the urgent task is to develop a new generation of antibacterial and bacteriostatic agents.

[0003] With the development of nanomedicine, it has been discovered that many nanoscale materials possess inherent antibacterial properties. In particular, inorganic semiconductor quantum dots exhibit outstanding antibacterial performance due to their inherent optical properties. However, because most inorganic semiconductor quantum dots contain heavy metals, they have poor biocompatibility and pose significant risks to human health, limiting their practical application. Carbon dots, as a new generation of quantum dot materials developed in recent years, have demonstrated advantages in application research in areas such as biosensing, photothermal therapy, drug delivery, and antibacterial applications due to their carbon atom-based composition, low cytotoxicity, good biocompatibility, and excellent fluorescence and photostability.

[0004] Currently, the relatively mature synthesis technology for fluorescent carbon quantum dots focuses on the blue-green light band, but its anti-interference ability, light penetration, and cell tissue damage are not as advantageous as those in the red light band. The synthesis strategy for red carbon quantum dots is still imperfect, and the mechanism is unclear, which remains a challenge. To solve this technical problem, existing technologies have made many beneficial explorations: For example, Chinese invention patent CN120290177A discloses a method for preparing red carbon quantum dots and its application. The resulting carbon quantum dots have uniform particle size and regular morphology, and achieve fluorescence emission in the red light band, exhibiting good antibacterial effects. However, its synthesis method requires the use of polyamines, which belong to the hazardous chemical category. Exploring safe and environmentally friendly raw materials is necessary for the synthesis process of carbon-based materials and for environmental friendliness. Chinese invention patent CN118599528A discloses a strategy for synthesizing red carbon quantum dots using evergreen and ethanol. However, the wavelength range of such biomass-synthesized red carbon dots is mostly around 700 nm, and it is difficult to achieve red light in the 600-700 nm range.

[0005] On the other hand, to enhance the antibacterial properties of carbon-based materials, Chinese invention patent CN119302311A prepared carbon quantum dots with the synergistic effect of nitrogen, sulfur, and copper ions to improve the antibacterial properties and water solubility of carbon materials; Chinese invention patent CN119371683A synthesized silver-doped carbon quantum dots, giving the hydrogel good biocompatibility and excellent antibacterial properties. However, both of these methods involve heavy metal doping, and excessive use may pose certain risks to human health and environmental safety. Therefore, this invention develops a sodium ion-doped carbon-based quantum dot synthesis strategy that uses safe and environmentally friendly raw materials as precursors to achieve long-wavelength red light region fluorescence emission and effective antibacterial activity. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing technologies and provide a sodium-doped antibacterial red-emitting carbon quantum dot and its preparation method. This method for preparing fluorescent carbon quantum dots is simple, non-toxic, and exhibits excellent dual-emission fluorescence characteristics in the red light region.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a method for preparing antibacterial red-emitting dual-emission carbon quantum dots based on sodium ion doping, comprising the following steps:

[0009] Step (1): Using deionized water as a solvent, add carbon source 3,4-diaminobenzenesulfonic acid and sodium-containing condensation reaction additive to the solvent respectively, and stir with a magnetic stirrer to ensure that the solute is fully dissolved and mixed evenly.

[0010] Step (2): Place the prepared solution into a reactor with an inert liner and carry out a high-temperature and high-pressure hydrothermal reaction;

[0011] Step (3): After the reaction is complete, the original product solution is purified by silica gel chromatography and dialyzed to obtain a red light dual-emission carbon quantum dot solution;

[0012] Step (4): Freeze and dry the obtained red light dual-emission carbon quantum dot solution, and then grind it to obtain red light dual-emission carbon quantum dot powder.

[0013] Preferably, in step (1), the mass ratio between the carbon source and the condensation reaction additive is 1:1 to 4, and the mass-volume ratio between the carbon source and deionized water is 1:150.

[0014] The sodium-containing condensation reaction additive is selected from acidic sodium salts, organic sodium salts, or a combination of sodium salts and phosphorus-related oxyacids.

[0015] The acidic sodium salt is selected from one or a combination of sodium dihydrogen phosphate, sodium hydrogen phosphite, sodium bisulfate, and sodium tartrate; the organic sodium salt is selected from one or a combination of sodium citrate, sodium acetate, and sodium malate; and the phosphorus-related oxyacids include one or a combination of phosphorous acid, orthophosphoric acid, metaphosphoric acid, hypophosphoric acid, and polyphosphoric acid.

[0016] The magnetic stirrer has a stirring speed of 1000 rpm and a stirring time of 20 to 30 minutes.

[0017] Preferably, in step (2), the reactor containing the inert inner liner is a polytetrafluoroethylene reactor; the volume ratio of the reaction liquid to the reactor volume is 3:5; the high-temperature and high-pressure hydrothermal reaction is carried out by heating at 200°C for 12 h.

[0018] Preferably, in step (3), when the obtained carbon quantum dot stock solution is purified by silica gel chromatography, the cleaning agent used is a mixed solution of ethanol and deionized water, and the volume ratio of ethanol to deionized water is 9:1.

[0019] During dialysis purification, the molecular weight cutoff of the dialysis bag was 500 Da, and dialysis with deionized water was performed for 48 h.

[0020] Preferably, in step (4), the freeze-drying conditions are as follows: freeze-drying at a temperature of -80 ~ -50℃ for 12 ~ 48 h.

[0021] In a second aspect, the present invention provides a red light dual-emitting carbon quantum dot antibacterial nanomaterial, which is prepared by the method described above.

[0022] SEM results showed that the carbon quantum dots obtained in this invention had good dispersion, with a statistically average particle size of approximately 4 nm. X-ray photoelectron spectroscopy revealed a characteristic peak for sodium near the binding energy of 1072.0 eV, indicating the successful preparation of sodium-doped carbon quantum dots. Fourier transform infrared spectroscopy showed multiple absorption peaks, confirming the abundance of functional groups on the surface of the carbon quantum dots. UV-Vis absorption spectroscopy showed distinct UV-Vis absorption peaks in five regions: 292 nm, 376 nm, 400 nm, 535 nm, and 572 nm. The red-emitting carbon quantum dots exhibited photofluorescence emission wavelengths of 600 nm and 650 nm, showing excitation-independent emission. Antibacterial tests showed that the carbon quantum dots obtained in this invention exhibited good antibacterial activity against Staphylococcus aureus, with an antibacterial rate of 57.17%.

[0023] Based on the above test results, in a third aspect, the present invention provides the application of red light dual-emitting carbon quantum dot nano-antibacterial materials.

[0024] Based on its safety, non-toxicity, and antibacterial properties, the first application provides the use of the aforementioned red light dual-emission carbon quantum dot nano-antibacterial material in the preparation of anti-Gram-positive bacteria, preferably Staphylococcus aureus.

[0025] Furthermore, the present invention also provides a pharmaceutical composition for combating Gram-positive bacteria, wherein the active component is the red light dual-emitting carbon quantum dot nano-antibacterial material described above.

[0026] Based on its antibacterial properties and excitation-independent dual-emission fluorescence in the red light band, the second application provides the material for use in the fabrication of deep tissue penetration imaging sensors, ratiometric fluorescence sensors, or optoelectronic devices for in vivo deep tissue penetration imaging.

[0027] The beneficial protections and effects of this invention are as follows:

[0028] In terms of safety, this invention uses 3,4-diaminobenzenesulfonic acid as a carbon source, sodium dihydrogen phosphate as an auxiliary additive, and deionized water as a solvent. All the selected precursor reaction raw materials are non-toxic, harmless, and non-hazardous chemicals, and the preparation process is green and environmentally friendly.

[0029] Regarding the product and preparation process, the red fluorescent carbon quantum dot product solution obtained by this invention is relatively pure, and the synthesis and cleaning purification steps are simple.

[0030] In terms of performance, the carbon quantum dots obtained by this invention have excitation-independent dual emission fluorescence characteristics in the red light band, and the material itself has good antibacterial properties, providing a new strategy for the application of carbon quantum dots in deep tissue penetration imaging, antibacterial therapy, ratio fluorescence sensing and optoelectronic devices.

[0031] In summary, the advantages of this invention lie in its ability to successfully obtain multifunctional carbon quantum dots with excitation-independent dual-emission fluorescence properties and antibacterial properties in the red light band through a simple and environmentally friendly preparation method. This solves the problems of traditional materials having single functions, complex preparation, or poor biocompatibility, and provides a new strategy with superior performance for antibacterial therapy. Attached Figure Description

[0032] Figure 1 Transmission electron microscope (TEM) image of the red light dual-emission carbon quantum dots prepared in this invention.

[0033] Figure 2 The X-ray photoelectron spectrum (XPS) of the red-light dual-emission carbon quantum dots prepared in this invention.

[0034] Figure 3 Fourier transform infrared (FT-IR) spectrum of the red-emitting dual-emission carbon quantum dots prepared in this invention.

[0035] Figure 4 The UV-Vis absorption spectrum of the red-emitting carbon quantum dots prepared in this invention.

[0036] Figure 5 Photofluorescence spectra (PL) of the red-light dual-emission carbon quantum dot solution prepared in this invention at different excitation wavelengths.

[0037] Figure 6 Photographs of the red-emitting dual-emission carbon quantum dot solution prepared for this invention under sunlight and ultraviolet light irradiation.

[0038] Figure 7 This image shows the antibacterial effect of the red-emitting dual-emission carbon quantum dots prepared in this invention on an in vitro plate coating. Detailed Implementation

[0039] The following embodiments and experimental examples further illustrate the present invention and should not be construed as limiting the invention. The embodiments do not include a detailed description of conventional methods, which are well known to those skilled in the art and described in numerous publications.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention, and the preferred embodiments and materials described in the specific implementation are for illustrative purposes only.

[0041] Unless otherwise specified, the experimental methods described in the following examples are generally performed under standard conditions or as recommended by the manufacturer.

[0042] I. Preparation of Red-Emitting Dual-Emitting Carbon Quantum Dots

[0043] Example 1:

[0044] (1) Weigh 0.4 g of 3,4-diaminobenzenesulfonic acid and 0.4 g of sodium dihydrogen phosphate and dissolve them in 60 mL of deionized water;

[0045] (2) Stir the mixed solution with a magnetic stirrer at 1000 rpm for 20 min until the two precursor reactants are completely mixed;

[0046] (3) Seal the mixture in a PTFE-lined autoclave (100 mL) and heat it at 200°C for 12 h.

[0047] (4) The obtained carbon quantum dot stock solution was purified by silica gel chromatography. The cleaning agent used was a mixed solution of ethanol and deionized water with a volume ratio of Vethanol / Vdeionized water = 9:1.

[0048] (5) After chromatography, the obtained solution is placed in a dialysis bag with a molecular weight cutoff of 500 Da. Dialysis with deionized water for 48 hours yields a solution containing red light dual-emission fluorescent carbon quantum dots. After freeze-drying, the solution is stored away from light.

[0049] (6) The morphology, chemical composition, optical properties and antibacterial properties of the carbon quantum dots obtained above were characterized by analytical methods such as TEM, FTIR, XPS, UV-vis, PL and plate coating counting method.

[0050] Example 2:

[0051] (1) Weigh 0.4 g of 3,4-diaminobenzenesulfonic acid and 0.8 g of sodium dihydrogen phosphate and dissolve them in 60 mL of deionized water;

[0052] (2) Stir the mixed solution with a magnetic stirrer at 1000 rpm for 20 min until the two precursor reactants are completely mixed;

[0053] (3) Seal the mixture in a PTFE-lined autoclave (100 mL) and heat it at 200°C for 12 h.

[0054] (4) The obtained carbon quantum dot stock solution was purified by silica gel chromatography. The cleaning agent used was a mixed solution of ethanol and deionized water with a volume ratio of Vethanol / Vdeionized water = 9:1.

[0055] (5) After chromatography, the obtained solution is placed in a dialysis bag with a molecular weight cutoff of 500 Da. The solution is dialyzed with deionized water for 48 h to obtain a solution containing red light dual-emission fluorescent carbon quantum dots. After freeze-drying, the solution is stored away from light.

[0056] (6) The morphology, chemical composition, optical properties and antibacterial properties of the carbon quantum dots obtained above were characterized by analytical methods such as TEM, FTIR, XPS, UV-vis, PL and plate coating counting method.

[0057] Example 3:

[0058] (1) Weigh 0.4 g of 3,4-diaminobenzenesulfonic acid and 1.2 g of sodium dihydrogen phosphate and dissolve them in 60 mL of deionized water;

[0059] (2) Stir the mixed solution with a magnetic stirrer at 1000 rpm for 20 min until the two precursor reactants are completely mixed;

[0060] (3) Seal the mixture in a PTFE-lined autoclave (100 mL) and heat it at 200°C for 12 h.

[0061] (4) The obtained carbon quantum dot stock solution was purified by silica gel chromatography. The cleaning agent used was a mixed solution of ethanol and deionized water with a volume ratio of Vethanol / Vdeionized water = 9:1.

[0062] (5) After chromatography, the obtained solution is placed in a dialysis bag with a molecular weight cutoff of 500 Da. The solution is dialyzed with deionized water for 48 h to obtain a solution containing red light dual-emission fluorescent carbon quantum dots. After freeze-drying, the solution is stored away from light.

[0063] (6) The morphology, chemical composition, optical properties and antibacterial properties of the carbon quantum dots obtained above were characterized by analytical methods such as TEM, FTIR, XPS, UV-vis, PL and plate coating counting method.

[0064] Example 4:

[0065] (1) Weigh 0.4 g of 3,4-diaminobenzenesulfonic acid and 1.6 g of sodium dihydrogen phosphate and dissolve them in 60 mL of deionized water;

[0066] (2) Stir the mixed solution with a magnetic stirrer at 1000 rpm for 20 min until the two precursor reactants are completely mixed;

[0067] (3) Seal the mixture in a PTFE-lined autoclave (100 mL) and heat it at 200°C for 12 h.

[0068] (4) The obtained carbon quantum dot stock solution was purified by silica gel chromatography. The cleaning agent used was a mixed solution of ethanol and deionized water with a volume ratio of Vethanol / Vdeionized water = 9:1.

[0069] (5) After chromatography, the obtained solution is placed in a dialysis bag with a molecular weight cutoff of 500 Da. Dialysis with deionized water for 48 hours yields a solution containing red light dual-emission fluorescent carbon quantum dots. After freeze-drying, the solution is stored away from light.

[0070] (6) The morphology, chemical composition, optical properties and antibacterial properties of the carbon quantum dots obtained above were characterized by analytical methods such as TEM, FTIR, XPS, UV-vis, PL and plate coating counting method.

[0071] II. Performance Characterization

[0072] 1. Morphological characteristics

[0073] The carbon quantum dots obtained in the above examples were observed under a TEM electron microscope, and the results are as follows: Figure 1 As shown in the transmission electron microscope image, the carbon quantum dots obtained in this invention have good dispersion, with a statistically average particle size of about 4 nm.

[0074] 2. Characterization of chemical composition

[0075] XPS and FTIR analyses were performed on the carbon quantum dots obtained in the above embodiments, and the results are as follows: Figure 2 and Figure 3 As shown: X-ray photoelectron spectrum Figure 2 As shown in the figure, a characteristic peak of sodium appears near the binding energy of 1072.0 eV, indicating that the present invention has successfully prepared carbon quantum dots doped with metallic sodium ions.

[0076] Fourier transform infrared spectrum as follows Figure 3 As shown, the appearance of multiple absorption peaks confirms that the carbon quantum dots obtained in this invention have abundant functional groups on their surface, such as at 3332 cm⁻¹. -1 The nearby characteristic absorption peak was identified as a stretching vibration of the NH / OH bond; 2927 cm⁻¹ -1 and 2883 cm -1 Identified as CH stretching vibration; at 1381 cm⁻¹ -1 1329 cm -1 1278 cm -1 The region was identified as an absorption band associated with the CN / S=O / P=O stretching vibration; located at 1087 cm⁻¹. -1 1047 cm -1 The absorption peak is attributed to the CO / POC stretching vibration; 881 cm⁻¹ -1 The surrounding area was identified as CH bending vibration and P-OH absorption band.

[0077] 3. Characterization of optical properties

[0078] like Figure 4 The UV-Vis absorption spectra show that the carbon quantum dots obtained in this invention exhibit significant absorption peaks at 292 nm, 376 nm and 400 nm, and 535 nm and 572 nm. The absorption peak at 292 nm originates from the π-π* transitions in the C=C bond conjugated structure, while the weak absorption peaks at 376 nm and 400 nm typically originate from n-π* transitions related to oxygen (O) and nitrogen (N) doping in the carbon dots. Furthermore, the weak absorption peaks at 535 nm and 572 nm are generally related to n-π* transitions associated with phosphorus (P) and sulfur (S) elements in the carbon dots.

[0079] like Figure 5As shown in the photoluminescence spectrum, under different excitation wavelengths from 410 to 530 nm, the carbon quantum dots obtained in this invention exhibit a broad double emission fluorescence in the long wavelength region of visible light. The centers of the two emission peaks are located at approximately 600 nm and 650 nm, respectively, and their peak positions do not change with the excitation wavelength, only affecting the fluorescence intensity, thus exhibiting excitation-independent characteristics.

[0080] like Figure 6 As shown in the comparison images, the carbon quantum dot solution samples obtained in this invention are photographed under sunlight and under ultraviolet light, and the differences are obvious.

[0081] 4. Characterization of antibacterial properties

[0082] The carbon quantum dots obtained in this invention were used to test the in vitro antibacterial activity of Staphylococcus aureus using a plate coating and counting method. Staphylococcus aureus was divided into a control group and an experimental group. The experimental group was coated with the carbon quantum dot solution obtained in this invention, while the control group was not coated. Both groups of Staphylococcus aureus were incubated at 37°C with shaking for 18 h, and then the colonies were counted. See the comparison diagram of the two plates. Figure 7 The colony count results are shown in Table 1, which shows that its antibacterial rate against Staphylococcus aureus reached 57.17%.

[0083] Table 1. Results of antibacterial test of red dual-emission carbon quantum dots against Staphylococcus aureus

[0084]

[0085] The undescribed parts of this invention are the same as or implemented using existing technology. The applicant declares that this invention is illustrated through the above embodiments, but the invention is not limited to the above detailed methods, i.e., it does not mean that the invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A method for preparing antibacterial red-emitting dual-emission carbon quantum dots based on sodium ion doping, characterized in that, Includes the following steps: Step (1): Using deionized water as a solvent, add carbon source 3,4-diaminobenzenesulfonic acid and sodium-containing condensation reaction additive to the solvent respectively, and stir with a magnetic stirrer to ensure that the solute is fully dissolved and mixed evenly. Step (2): Place the prepared solution into a reactor with an inert liner and carry out a high-temperature and high-pressure hydrothermal reaction; Step (3): After the reaction is complete, the original product solution is purified by silica gel chromatography and dialyzed to obtain a red light dual-emission carbon quantum dot solution; Step (4): Freeze and dry the obtained red light dual-emission carbon quantum dot solution, and then grind it to obtain red light dual-emission carbon quantum dot powder.

2. The preparation method according to claim 1, characterized in that: in, In step (1), the mass ratio between the carbon source and the condensation reaction additive is 1:1 ~ 4, and the mass-volume ratio between the carbon source and deionized water is 1:

150. The sodium-containing condensation reaction additive is selected from acidic sodium salts, organic sodium salts, or combinations of sodium salts and phosphorus-related oxyacids. The acidic sodium salt is selected from one or a combination of several of sodium dihydrogen phosphate, sodium hydrogen phosphite, sodium bisulfate, and sodium hydrogen tartrate. The organic sodium salt is selected from one or a combination of sodium citrate, sodium acetate, and sodium malate; The phosphorus-related oxyacids include one or a combination of several of the following: phosphorous acid, orthophosphoric acid, metaphosphoric acid, hypophosphoric acid, and polyphosphoric acid. The magnetic stirrer has a stirring speed of 1000 rpm and a stirring time of 20 to 30 minutes.

3. The preparation method according to claim 1, characterized in that: in, In step (2), the reactor with an inert inner liner is a polytetrafluoroethylene reactor; in step (1), the volume ratio of the reaction liquid to the reactor volume is 3:5; The high-temperature and high-pressure hydrothermal reaction involves heating at 200°C for 12 hours.

4. The preparation method according to claim 1, characterized in that: in, In step (3), when the obtained carbon quantum dot stock solution is purified by silica gel chromatography, the cleaning agent used is a mixed solution of ethanol and deionized water, with a volume ratio of ethanol to deionized water of 9:

1. During dialysis purification, the molecular weight cutoff of the dialysis bag was 500 Da, and dialysis with deionized water was performed for 48 h.

5. The preparation method according to claim 1, characterized in that... ； In step (4), the freeze-drying conditions are as follows: freeze-drying at a temperature of -80 ~ -50℃ for 12 ~ 48 hours.

6. A red-light dual-emitting carbon quantum dot nanomaterial for antibacterial purposes, characterized in that, It is prepared by the method described in any one of claims 1 to 5.

7. The red-light dual-emitting carbon quantum dot antibacterial nanomaterial according to claim 6, characterized in that, The carbon quantum dots of this material have obvious ultraviolet-visible absorption peaks in five regions: 292 nm, 376 nm, 400 nm, 535 nm and 572 nm. The red-light dual-emission carbon quantum dots exhibit photofluorescence emission wavelengths of 600 nm and 650 nm, respectively, and are excitation-independent.

8. The application of the red light dual-emission carbon quantum dot antibacterial nanomaterial according to claim 6 or 7 in the preparation of anti-Gram-positive bacteria.

9. A pharmaceutical composition for combating Gram-positive bacteria, characterized in that, Its active component is the red light dual-emitting carbon quantum dot nano-antibacterial material as described in claim 6 or 7.

10. The application of the red-light dual-emission carbon quantum dot antibacterial nanomaterial according to claim 6 or 7 in the preparation of deep tissue penetration imaging sensors, ratio fluorescence sensors or optoelectronic devices.

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