Modified graphite-phase carbon nitride material grafted with boric acid group as well as preparation method and application of modified graphite-phase carbon nitride material
By grafting boric acid groups on graphite phase carbon nitride material, the problem of insufficient photocatalytic bactericidal performance of the material is solved, and efficient killing and environmentally friendly sterilization effects of drug-resistant bacteria are achieved.
Patent Information
- Application Number
- CN202510069979.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-16
- Publication Date
- 2025-05-16
AI Technical Summary
The photogenerated electron-hole recombination rate of the original graphite phase carbon nitride material is high, but the photogenerated carrier transmission capacity is poor, resulting in insufficient photocatalytic sterilization performance.
The boric acid groups with alkyl chains are grafted on the graphite phase carbon nitride (g-C3N4) to form the modified graphite phase carbon nitride material CN-B to improve the separation and transport capability of photogenerated carriers.
By grafting boric acid groups, the photocatalytic bactericidal properties of the material are significantly improved, which can effectively kill drug-resistant bacteria, and directly use sunlight to achieve inactivation of bacteria in water.
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Figure CN119999697A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of bactericidal materials, and in particular to a modified graphite phase carbon nitride material grafted with boric acid groups, a preparation method and application thereof. Background Art
[0002] The emergence of drug-resistant bacteria is caused by the abuse of antibiotics. The so-called bacterial resistance refers to the fact that after repeated contact with drugs, the sensitivity of bacteria to drugs decreases or even disappears, resulting in reduced or even ineffective efficacy of drugs against drug-resistant bacteria. Many antibiotics have shown varying degrees of reduced efficacy after years of use, and natural penicillin has almost lost its medicinal value in controlling Staphylococcus aureus infections. Multidrug-resistant bacteria, Acinetobacter baumannii, have emerged, which are resistant to three or more of the five commonly used clinical antibacterial drugs. At present, there is an urgent need to develop methods that can effectively kill drug-resistant bacteria. Photodynamic therapy and photocatalytic therapy are based on light excitation to produce reactive oxygen species to destroy the bacterial membrane structure, which will not induce bacterial resistance and are effective methods to kill drug-resistant bacteria.
[0003] As a typical photocatalytic material, g-C3N4 is easy to prepare, low-cost, environmentally friendly and pollution-free. It can be easily obtained from the thermal decomposition of melamine, dicyandiamide or urea. Its photocatalytic reaction affects its antibacterial properties. When the energy of visible light irradiating g-C3N4 is greater than the band gap energy of g-C3N4, e- jumps from VB to CB, generating electrons (e-) and holes (h+), and e- / h+ can recombine on the surface of g-C3N4. The remaining e- / h+ pairs are transmitted to the g-C3N4 interface through electric field diffusion and undergo redox reactions with surrounding oxygen-containing substances. Therefore, under visible light irradiation, g-C3N4 produces ROS, which can destroy bacterial cell membranes, cause cell membrane permeability, and destroy the structure, ultimately killing bacteria. The original graphite phase carbon nitride has a high recombination rate of photogenerated electrons and holes, but the poor transmission capacity of photogenerated carriers leads to insufficient photocatalytic bactericidal performance.
[0004] Boric acid groups can selectively bind to molecules with cis-diol structures (such as sugars) through covalent bonds through reversible esterification reactions. Peptidoglycan and lipopolysaccharide with cis-diol structures are abundant on bacterial cell walls. Boric acid can thus destroy the integrity and permeability of cell membranes, leading to extravasation of substances inside cells and ultimately cell death. In addition, boric acid groups can interfere with the metabolic process of microorganisms, affecting their growth and reproduction, thereby achieving a bactericidal effect. Summary of the invention
[0005] The present invention aims to solve the defects of insufficient photocatalytic bactericidal performance of original graphite phase carbon nitride due to high photogenerated electron-hole recombination rate and poor photogenerated carrier transport capacity, and provides a modified graphite phase carbon nitride material with grafted boric acid groups. The modified graphite phase carbon nitride material CN-B is obtained by grafting boric acid groups with alkyl chains on graphite phase carbon nitride (g-C3N4), so as to achieve high efficiency in combating drug-resistant bacteria.
[0006] The present invention first provides a modified graphite phase carbon nitride material grafted with boric acid groups, wherein a boric acid group with an alkyl chain is grafted onto graphite phase carbon nitride (g-C3N4) to obtain the modified graphite phase carbon nitride material CN-B.
[0007] Furthermore, the grafted alkyl chain length is 4, and the modified graphite phase carbon nitride material CN-C4-B has the structural formula: .
[0008] The present invention also provides a method for preparing the modified graphite phase carbon nitride material, which is specifically: Step 1: Using graphite carbon nitride (g-C3N4) and 1,4-dibromobutane as raw materials, K2CO as catalyst, and dimethyl sulfoxide as solvent, reacting at 80-100°C, and then drying and grinding to obtain an intermediate of grafting an alkyl carbon chain on g-C3N4; Step 2: react the intermediate obtained in step 1 with 3-pyridineboric acid at 65-70° C., wash the reaction product with an organic solvent, dry and grind to obtain a light yellow powder, which is a modified graphite phase carbon nitride material grafted with boric acid groups with four alkyl chains, abbreviated as CN-C4-B.
[0009] Furthermore, in step 1, the molar ratio of 1,4-dibromobutane:g-C3N4 is 6:1, and the reaction time is 20-24h; the reaction product is washed with petroleum ether 5-8 times, then washed with ethanol 2-3 times, and then centrifuged, dried, and ground to obtain the intermediate.
[0010] Furthermore, in step 2, the molar ratio of the intermediate to 3-pyridine boronic acid is 1:5, the solvent is dimethyl sulfoxide, the reaction time is 20-24 hours, the reaction product is washed with petroleum ether for 3-5 times, then washed with ethanol, and then centrifuged, dried, and ground to obtain CN-C4-B.
[0011] Furthermore, the graphite phase carbon nitride (g-C3N4) of the present invention is prepared by the following method: melamine is calcined at 540-560°C for 3-5 hours, and then cooled to room temperature to obtain g-C3N4.
[0012] The present invention also provides an application of the modified graphite phase carbon nitride material grafted with boric acid groups in the preparation of drugs for resisting drug-resistant bacteria.
[0013] Furthermore, the drug-resistant bacteria include at least one of Gram-negative bacteria and Gram-positive bacteria.
[0014] The modified graphite phase carbon nitride material grafted with boric acid groups and the preparation method thereof of the present invention have the following beneficial effects: the synthesis steps of the material are simple and the cost is low; the modified material expands the response range of the original graphite phase carbon nitride to visible light, has a more efficient photogenerated carrier separation and transmission capability, and at the same time enhances the contact effect between pathogens and the carbon nitride material, which is conducive to better exerting the bactericidal performance, and directly utilizes sunlight to achieve the inactivation of drug-resistant bacteria in water bodies, and is an environmentally friendly sterilization material. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is the Fourier infrared image of CN-C4-B and g-C3N4 of the present invention.
[0016] Figure 2 It is the XRD diagram of CN-C4-B and g-C3N4 of the present invention.
[0017] Figure 3 These are the photoluminescence spectra of modified carbon nitride and g-C3N4 with different carbon chain lengths.
[0018] Figure 4 Electron paramagnetic resonance spectra of singlet oxygen yield detected in a series of graphitic carbon nitride and g-C3N4 modified with boric acid groups of different alkyl chain lengths.
[0019] Figure 5 1 and 2 are scanning electron microscope images of bacteria before and after photocatalytic sterilization by CN-C4-B of the present invention; in the figure, (a) and (b) are electron microscope images of Acinetobacter baumannii before and after sterilization by CN-C4-B, and (c) and (d) are electron microscope images of Staphylococcus aureus before and after sterilization, respectively.
[0020] Figure 6 This is a picture showing the effect of the photocatalytic killing of Acinetobacter baumannii by CN-C4-B; in the figure, (a), (b), (c), and (d) are photos of the colony plates after 0 min, 20 min, 40 min, and 60 min of illumination, respectively. DETAILED DESCRIPTION
[0021] The modified graphite phase carbon nitride material grafted with boric acid groups, the preparation method and the application thereof of the present invention are described below by means of specific embodiments and comparative examples in conjunction with the accompanying drawings. Example 1
[0022] In this embodiment, a modified graphite phase carbon nitride material grafted with boric acid groups is prepared, and the synthesis is carried out according to the following steps: 1) Using melamine as a precursor, weigh 4 g of melamine and place it in a dry and clean covered crucible, move it to a muffle furnace for calcination, set the heating rate to 5 ° C / min, heat it to 550 ° C and keep it at 550 ° C for 3 hours, take it out after cooling to room temperature, wash, dry and grind it to obtain g-C3N4 powder. The reaction process is as follows: .
[0023] (2) 1.5 g of the g-C3N4 powder obtained in step 1) was added to 18 ml of dimethyl sulfoxide (DMSO) solvent with 1,4-dibromobutane (2.57 g, 11.8 mmol) and 0.2 g of catalyst K2CO3. The mixture was reacted at 90 °C for 24 h. The product was washed with petroleum ether for 8 times and dried in a vacuum oven at 60 °C overnight. After grinding, 2.54 g of light yellow powder was obtained, which was the modified product intermediate with four alkyl carbon chains grafted onto g-C3N4. The reaction formula is as follows: .
[0024] (3) 0.4 g of the modified intermediate prepared in step 2) and 3-pyridine boronic acid (0.67 g, 5.4 mmol) were added to 16 ml of dimethyl sulfoxide solvent and stirred at 70 °C for 24 hours. The product was washed with petroleum ether and ethanol, dried overnight, and ground to obtain 0.311 g of a light yellow product, which is a modified graphite phase carbon nitride grafted with a boric acid group with a length of 4 alkyl chains, abbreviated as CN-C4-B. The reaction formula is as follows: .
[0025] In addition, referring to the above preparation method, CN-C2-B, CN-C6-B, CN-C8-B, CN-C 10 -B series modified g-C3N4 photocatalytic materials, wherein the difference is that the raw materials of the modified product intermediates of two alkyl carbon chains, six alkyl carbon chains, eight alkyl carbon chains and ten alkyl carbon chains synthesized in step (2) are 1,2-dibromoethane; 1,6-dibromohexane; 1,8-dibromooctane; 1,10-dibromodecane, respectively, and the reaction conditions and synthesis steps are consistent with CN-C4-B, and finally the following chemical structural formula modified graphite phase carbon nitride materials are synthesized respectively.
[0026] . Example 2
[0027] (1) Preparation of broth medium (LB) Disperse 2.00 g NaCl, 1.00 g yeast powder and 2.00 g peptone in a conical flask filled with 200 mL ultrapure water, seal it with kraft paper, place it in a high pressure steam sterilizer at 121 °C for 20 min, and take it out after cooling to room temperature to obtain a liquid culture medium. For the solid culture medium, add 3.00 g agar powder to the above formula, sterilize it at 121 °C, pour it into the culture dish while it is hot, and store it in a refrigerator at 4 °C after it is completely solidified.
[0028] (2) Preparation of phosphate buffered saline (PBS) Dissolve 1.45 g Na2HPO4•12H2O, 4.00 g NaCl, 0.10 g KCl and 0.24 g KH2PO4 in a glass bottle filled with 500 mL ultrapure water. Do not tighten the bottle cap. Sterilize at 121°C for 20 min in a high-pressure steam sterilizer. After cooling to room temperature, obtain PBS buffer solution, which is stored in a clean bench at room temperature. The sterilized PBS buffer solution is used as the environmental solution in the photosensitized sterilization reaction system.
[0029] (3) Bacterial culture Multidrug-resistant Gram-negative Acinetobacter baumannii (AB) and Gram-positive Staphylococcus aureus (SA) were selected as representatives for photocatalytic sterilization experiments. The bacteria were cultured in a liquid culture medium at 37°C in a constant temperature shaker until the logarithmic phase, and the bacterial density OD was measured by a nucleic acid / protein analyzer. 600 The value is about 0.5. Collect 1 mL of bacterial solution, centrifuge at 5000 rpm / min for 5 min, and aspirate the supernatant. Then wash twice with phosphate buffered saline (PBS), repeat the above centrifugation process, and disperse in PBS solution for the third time. The final concentration is about 10 8 CFU / ml.
[0030] (4) Photocatalytic sterilization process The power supply system selected was a CEL-HXF300W xenon lamp equipped with a 400 nm-QD-filter and a CEL-NP2000 high-intensity light power meter. Multidrug-resistant Acinetobacter baumannii (AB) and Staphylococcus aureus (SA) were selected as representatives of Gram-negative and Gram-positive bacteria for photocatalytic sterilization experiments. 20 mg of photocatalyst was added to 10 mL PBS containing 100 μL of bacterial solution. The photocatalyst concentration was 2 mg / ml and the bacterial solution concentration was 2*10 6 cfu / ml, and placed under a xenon lamp for illumination. During the photocatalytic experiment, the light power density was maintained at 100 hw / cm 2,The reaction mixture was stirred with a magnetic stirrer throughout the experiment to ensure uniform distribution of the photocatalyst and bacteria. To avoid the influence of temperature, all experiments were performed in an ice bath and repeated three times.
[0031] (5) Calculation of sterilization efficiency The bacterial concentration at different durations was determined using standard spot plate counts. Take out 21 1 mL EP tubes and add 900 μL of PBS buffer solution to each. First, use a pipette to transfer 100 μL of the original experimental solution and dilute the solution to 10% of the original concentration. -1 , 10 -2 , 10 -3 , diluted to 10 -3 Take 100 μL of the bacterial solution for plating. Put the solid culture medium plate after plating into a 37℃ constant temperature incubator and culture it overnight for 15 hours. When bacterial colonies are visible to the naked eye, count the number of colonies on the culture plate at different time periods.
[0032] The sterilization efficiency is calculated using the formula: Where C is the number of colonies present in the plate at different time periods during the illumination period, C 0 It is the number of colonies grown on the solid culture medium when the bacterial solution is plated before light sterilization.
[0033] The bactericidal rate results of g-C3N4 and a series of carbon nitrides modified with boric acid groups grafted with different alkyl chain lengths are shown in the following table.
[0034]
[0035] .
[0036] From the comparative data of sterilization rates in the above two tables, it can be seen that the sterilization performance of carbon nitride modified materials grafted with boric acid groups of different alkyl chain lengths is significantly better than that of unmodified materials, but CN-C4-B grafted with four alkyl chain lengths has the best sterilization effect. The sterilization rate of CN-C4-B against Acinetobacter baumannii reached 99.75% at 60 minutes and 99.98% at 180 minutes against Staphylococcus aureus. The sterilization efficiency of CN-C4-B is more than doubled compared with g-C3N4 before modification. It has a strong killing effect on both resistant Gram-negative bacteria and Gram-positive bacteria, which shows that it has excellent photocatalytic oxidation sterilization performance. The sterilization efficiency of CN-C4-B against Staphylococcus aureus and Acinetobacter baumannii is better than that of CN-C2-B, CN-C6-B, CN-C8-B, and CN-C 10-B. From the experimental results, the grafting of boric acid groups is beneficial to improving the photocatalytic bactericidal performance of g-C3N4, and the length of the alkyl chain also affects the bactericidal performance. For the modified graphene phase carbon nitride grafted with boric acid groups, too long or too short side chain length is not conducive to fully exerting the bactericidal effect, and the photocatalytic sterilization effect is best when the alkyl chain length is 4.
[0037] like Figure 1 The following are Fourier transform infrared images of the modified graphite phase carbon nitride materials CN-C4-B and g-C3N4 in Example 1. -1 The characteristic peak for the stretching vibration absorption peak of -OH; at 811cm -1 The characteristic peak at 850~600 cm corresponds to the bending vibration of the triazine ring. -1 The peak between 2900 and 2800 cm is caused by the stretching vibration of the bromine-carbon bond. -1 The position of is due to the vibration characteristics of the CH bond. In the bromine-substituted molecules, the CH bond on the carbon atom adjacent to the bromine atom usually produces a strong absorption peak. The successful synthesis of the modified graphite phase carbon nitride grafted with boric acid groups was proved by infrared.
[0038] Figure 2 The XRD patterns of CN-C4-B and g-C3N4 in Example 1 are shown in Figure 1. The original g-C3N4 exhibits two typical diffraction peaks, at 13.1°(100) and 27.2°(002). The (100) plane is attributed to the planar structure of the heterocyclic system connected to N, and the (002) plane is attributed to the interlayer superposition of the conjugated aromatic rings. There is no shift or intensity change of the diffraction peaks in the XRD pattern of the modified material CN-C4-B, indicating that the crystal structure and crystal order of the photocatalytic material have no obvious changes during the chemical modification process.
[0039] Figure 3The photoluminescence spectra of a series of modified graphite phase carbon nitride and g-C3N4 grafted with boric acid groups of different alkyl chain lengths in Example 1. In order to better study the recombination of photoinduced carriers, steady-state photoluminescence analysis (PL) was performed. Photoluminescence helps to reveal the recombination efficiency of photogenerated carriers in semiconductors. When the sample is excited by light, the generated electrons jump from VB to CB and leave holes on VB. Holes and electrons relax on their respective VB and CB to reach their respective unoccupied lowest excited states, becoming quasi-equilibrium states. In the quasi-equilibrium state, holes and electrons re-emit through secondary recombination luminescence, forming spectra with different emission intensities or energy distributions of wavelengths of light with different emission frequencies, where the stronger the PL peak in the spectrum, the higher the recombination rate of electron-hole pairs, which also means that their separation rate is low, which is unfavorable to photocatalytic performance. The photoluminescence intensity of the modified g-C3N4-based photocatalytic material CN-C4-B is significantly lower than that of the original g-C3N4, and the fluorescence intensity is also lower than that of modified carbon nitrides with other chain lengths, indicating that CN-C4-B can effectively increase the migration rate of photogenerated carriers, reduce the recombination of photogenerated carriers, and has the best photocatalytic performance.
[0040] Figure 4 The electron paramagnetic resonance spectra of the singlet oxygen yield of a series of modified graphene carbon nitride and g-C3N4 grafted with boric acid groups of different alkyl chain lengths in Example 1. 2,2,6,6-tetramethyl-4-piperidone (TEMP) was selected as the capture agent for EPR testing. Studies have shown that 1O 2 It can be captured and detected by TEMP at a detection limit of 100 nM, generating a specific TEMPO triple signal peak with an intensity of 1:1:1. The appearance of the TEMPO signal peak is considered to be the generation of 1O 2 Solid evidence. The TEMP baseline has no interfering EPR signal from TEMPO, has good stability, and does not generate an EPR signal peak. After TEMP captures singlet oxygen, it can form a stable nitrogen oxide free radical TEMPO. By analyzing the EPR signal of TEMPO and combining it with the reaction process, the rate and concentration change of singlet oxygen generation can be obtained. Figure 4 As shown in the figure, for the blank group TEMP, the signal peak is weak, almost a straight line, while the signal peak intensity of g-C3N4 is significantly lower than that of other modified materials. After grafting boric acid groups with different alkyl chain lengths, the oxygen vacancy signal of the g-C3N4 series samples is more obvious, among which the CN-C4-B sample has the highest singlet oxygen signal peak intensity.
[0041] Figure 5The bacterial solution of CN-C4-B before and after sterilization was placed in a centrifuge at 7000 rpm / min for 5 minutes, the supernatant was removed and 20-30 μL of PBS buffer solution was retained, which was evenly dispersed with a pipette, 10 μL of bacterial solution was added to the silicon wafer, and then 100 μL of 1% glutaraldehyde fixative was added for fixation. The glutaraldehyde fixative in the above samples was aspirated and treated with ethanol using a concentration gradient dehydration method, i.e. 50% - 70% -80% - 90% - 95% -100% - 100% (with anhydrous sodium sulfate), and each dehydration time was 10-15 minutes. When the ethanol concentration was less than or equal to 70%, the sample was placed in a 4°C refrigerator during dehydration. After dehydration, the sample was placed in a vacuum drying oven at 25°C for 4-5 hours. Then a scanning electron microscope was used to observe the morphology of the bacteria, such as Figure 5 In the figure, (a) and (b) are electron microscopic images of Acinetobacter baumannii before and after sterilization by CN-C4-B, and (c) and (d) are electron microscopic images of Staphylococcus aureus before and after sterilization.
[0042] Figure 6 The effect diagram of the photocatalytic killing of Acinetobacter baumannii by CN-C4-B. In the figure, (a), (b), (c), and (d) are photos of the colony plates after 0min, 20min, 40min, and 60min of illumination respectively. The plate colony counting method is based on the phenomenon that a colony formed by microorganisms on a solid culture medium is multiplied by a single cell, that is, a colony represents a single cell. By counting the number of colonies, the number of bacteria in the sample can be calculated. It can be seen from the effect diagram that as the illumination time increases, the number of bacteria gradually decreases, until after 60min, the bacteria are basically killed.
[0043] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.
Claims
1. A modified graphite phase carbon nitride material grafted with boric acid groups, characterized in that: The modified graphite carbon nitride material CN-B was obtained by grafting boric acid groups with alkyl chains onto graphite carbon nitride (g-C3N4).
2. The modified graphite phase carbon nitride material according to claim 1, characterized in that: The grafted alkyl chain length of 4 modified graphite phase carbon nitride material CN-C4-B has the following structural formula: 。 3. The method for preparing the modified graphite phase carbon nitride material according to claim 2, characterized in that: Step 1: Using graphite carbon nitride (g-C3N4) and 1,4-dibromobutane as raw materials, K2CO as catalyst, and dimethyl sulfoxide as solvent, reacting at 80-100°C, and then drying and grinding to obtain an intermediate of grafting an alkyl carbon chain on g-C3N4; Step 2: react the intermediate obtained in step 1 with 3-pyridineboric acid at 65-70° C., wash the reaction product with an organic solvent, dry and grind to obtain a light yellow powder, which is a modified graphite phase carbon nitride material grafted with boric acid groups with four alkyl chains, abbreviated as CN-C4-B.
4. The method for preparing the modified graphite phase carbon nitride material according to claim 2, characterized in that: In step 1, the molar ratio of 1,4-dibromobutane:g-C3N4 is 6:1, and the reaction time is 20-24h; the reaction product is washed with petroleum ether for 5-8 times, and then washed with ethanol for 2-3 times, and then centrifuged, dried, and ground to obtain the intermediate.
5. The method for preparing the modified graphite phase carbon nitride material according to claim 2, characterized in that: In step 2, the molar ratio of the intermediate to 3-pyridine boronic acid is 1:5, the solvent is dimethyl sulfoxide, the reaction time is 20-24 hours, the reaction product is washed with petroleum ether 3-5 times, then washed with ethanol, and then centrifuged, dried, and ground to obtain CN-C4-B.
6. The method for preparing the modified graphite phase carbon nitride material according to claim 2, characterized in that: The graphite phase carbon nitride (g-C3N4) is prepared by the following method: melamine is calcined at 540-560° C. for 3-5 hours, and then cooled to room temperature to obtain g-C3N4.
7. Use of the modified graphite phase carbon nitride material grafted with boric acid groups as claimed in claim 1 or 2 in the preparation of drugs against drug-resistant bacteria.
8. The use according to claim 7, wherein the drug-resistant bacteria at least include Gram-negative bacteria and / or Gram-positive bacteria.