A cuprous oxide-containing covalent organic framework with photo-sterilization activity and a synthesis method thereof

Abstract

The application discloses a cuprous oxide-containing covalent organic framework with photo-induced sterilization activity and a synthesis method thereof. Firstly, nano Cu2O powder is mixed with 1,4-phenyl diboronic acid monomers, a mixed solvent composed of APTES, dioxane and toluene is added, the reaction system is sealed after ultrasonic mixing, and then reaction is carried out, so that the cuprous oxide-containing covalent organic framework is obtained. The cuprous oxide with the covalent organic framework structure prepared by the application can be used as an antibacterial material, has high antibacterial activity, and has a certain killing effect on drug-resistant E. coli. Compared with antibacterial kinetics, the cuprous oxide with the covalent organic framework structure can kill more than 99% of bacteria.

Description

TECHNICAL FIELD

[0001] The present application relates to a cuprous oxide-containing covalent organic framework with photo-sterilization activity and a synthesis method thereof, and belongs to the field of antibacterial. BACKGROUND

[0002] For a long time, pollution caused by the mixing of pollutants and bacteria in the water environment has been constantly threatening the living environment and health of human beings, and such pollution is difficult to eliminate by traditional water treatment processes. Such adverse conditions cause great damage to the ecological system, human health and sustainable development of the economic society. To remove the contaminated bacteria in water, the more traditional method is to add antibiotics in the process of killing bacteria in sewage. However, over time, the overuse of antibiotics leads to the emergence of drug-resistant bacteria, thus greatly reducing the effectiveness of antibiotic sterilization. Therefore, it is necessary to develop a simple and effective method to degrade pollutants and kill drug-resistant bacteria, and such a method will not make bacteria resistant, which will have important significance for environmental and ecological stability.

[0003] As a kind of increasingly mature treatment method, photocatalytic antibacterial therapy can produce reactive oxygen species (ROS) to attack bacterial cell walls and intracellular mitochondria through photocatalytic process, resulting in bacterial lysis and death. The bactericidal process of ROS is not specific, so bacteria are difficult to develop drug resistance similar to that after the action of antibiotics. As a kind of relatively advanced material, covalent organic framework (COFs) material is widely used in various biological medical directions such as drug delivery, treatment, diagnosis and biotechnology due to its variability, high porosity and non-metallic structure.

[0004] Boron-based COF is one of the earliest types of COF, mainly produced by boroxin and borate, and occupies a place in the field of photocatalysis due to its unique element composition (electron-deficient boron) and extended conjugation effect. Boron-based COF is a simple cyclic material, easy to synthesize, and has biocompatibility and biodegradability. Most importantly, studies have shown that the earliest boron compounds can produce various ROS under visible light irradiation, which lays a foundation for the application of boron-based COF in the field of antibacterial. However, as an antibacterial material, the antibacterial activity of boron-based COF needs to be improved. Since COFs material has the characteristics of easy modification, it is feasible to improve the antibacterial activity of COFs material by modification, such as loading porphyrin, loading cation, and composite of COFs and biological materials, which all have broad application prospects.

[0005] As photosensitizers, porphyrins are expensive, so it is necessary to find a cheaper alternative. In recent years, inorganic nanomaterials have attracted much attention due to their controllable shape and size and effective photocatalytic activity, such as metal oxide semiconductors (TiO2, Cu2O, etc.) or narrow-band semiconductors (Ag3PO4). At the same time, there is evidence that the photocatalytic performance of these inorganic metals is related to their own morphology and size, so the antibacterial performance of the material can be adjusted by controlling the morphology of the metal. Among various metal oxides, cuprous oxide (Cu2O) is a low-cost and widely used antibacterial material. Cu2O is a P-type semiconductor with a band gap corresponding to the wavelength range of visible light. It is suitable for direct excitation by sunlight and has the characteristics of photocatalysis and photoelectrocatalysis, and has great application potential in the field of antibacterial and other fields. Cu2O can produce various ROS under visible light irradiation and release copper ions in the solution for synergistic antibacterial effect. The morphology, crystal surface, particle size, hydrophilicity and other conditions of Cu2O can affect the antibacterial effect. The smaller the nano-Cu2O particles, the higher the biological activity. SUMMARY

[0006] The application provides a cuprous oxide-containing covalent organic framework with photo-induced sterilization activity and a synthesis method thereof, and aims to solve the technical problem of combining antibacterial material cuprous oxide (Cu2O) with boron-based COF to prepare a novel nanocomposite and applying it to the antibacterial field.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] The synthesis method of the cuprous oxide-containing covalent organic framework with photo-induced sterilization activity is characterized in that: first, nano-Cu2O powder is mixed with 1,4-phenyl diboronic acid (BDBA) monomers, then a mixed solvent composed of APTES, dioxane and toluene is added, the reaction system is sealed after ultrasonic mixing, and then the reaction is carried out; after the reaction is completed, the product is collected, washed, filtered and vacuum dried to obtain the cuprous oxide-containing covalent organic framework. Specifically, the method comprises the following steps:

[0009] Further, the amount ratio of nano-Cu2O powder, 1,4-phenyl diboronic acid and mixed solvent is 20-100 mg: 250 mg: 10 mL.

[0010] Further, in the mixed solvent, the amount ratio of APTES, dioxane and toluene is 75 mg: 5 mL: 5 mL.

[0011] Further, the particle size of the nano-Cu2O powder is 50-100 nm.

[0012] Further, the washing and filtering are carried out by ultrasonic washing in acetone and then filtering.

[0013] Further, the vacuum drying is drying in a vacuum oven at 60-75 DEG C for 24-48 h.

[0014] The beneficial effects of the present application are embodied in:

[0015] 1. The cuprous oxide-containing covalent organic framework prepared in the present application can be used as antibacterial material, has high antibacterial activity, and also has a certain killing effect on drug-resistant E. coli. Compared with antibacterial kinetics, the cuprous oxide-containing covalent organic framework can complete the killing of more than 99% of bacteria.

[0016] 2. The cuprous oxide-containing covalent organic framework synthesized in the present application effectively improves the photocatalytic antibacterial efficiency of pure boron-based COF, has good bactericidal efficiency on bacteria with antibiotic resistance, and the raw materials are cheap and easy to obtain.

[0017] 3. The cuprous oxide-containing covalent organic framework synthesized in the present application has good biocompatibility and drug resistance. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 TEM image of COF-1 obtained in Comparative Example 1 of the present application.

[0019] Figure 2 TEM image of Cu2O-COF-1 obtained in Example 1 of the present application.

[0020] Figure 3 Plate coating result diagram of Cu2O-COF-1 obtained in Example 1 of the present application under light (L) and dark (D) conditions and co-cultured with S. aureus and E. coli for 30 min.

[0021] Figure 4 Antibacterial rate comparison line graph of Cu2O-COF-1 obtained in Example 1 of the present application under light (L) and dark (D) conditions, against E. coli and S. aureus, wherein a is the light (L) and dark (D) antibacterial rate comparison line graph of E. coli, and b is the light (L) and dark (D) antibacterial rate comparison line graph of S. aureus.

[0022] Figure 5 Plate coating result diagram of COF-1 obtained in Comparative Example 1 of the present application under light (L) and dark (D) conditions and co-cultured with S. aureus and E. coli for different times.

[0023] Figure 6Laser confocal scanning microscope images of E. coli and S. aureus for untreated and Cu2O-COF-1 treated groups.

[0024] Figure 7 XRD image of Cu2O-COF-1 obtained in Example 1 of the present application.

[0025] Figure 8 Photocurrent response test images of Cu2O-COF-1, COF-1 and Cu2O obtained in Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0026] The following detailed description of the embodiments of the present application is given on the premise of the technical solutions of the present application, and detailed implementation manners and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0027] Comparative Example 1

[0028] For comparison, a pure boron-based COF was prepared in this embodiment, and the method was as follows: 250.0 mg (1.5 mmol) of BDBA, 75.0 mg (0.34 mmol) of 3-aminopropyltriethoxysilane (APTES), 5 mL of mesitylene and 5 mL of 1,4-dioxane were added to a pre-washed and dried 20 mL PYREX test tube. The reaction mixture was ultrasonically treated for 30 min, and then a degassing process was performed three times using the cycle of “frozen to solid state, vacuumized, nitrogenized, thawed to liquid state”. Then the test tube was flame sealed, and the mixture was ultrasonically treated for 1 h again. Finally, the test tube was heat preserved and stirred at 75 °C for 24 h in an oil bath.

[0029] At the end of the reaction, the product was collected (filtered with a Buchner funnel), washed with acetone for 5 h (to wash away monomers and high-boiling solvents) under ultrasonication, and then filtered, and the washing and filtering steps were repeated three times, and then the product was dried in a vacuum oven at 75 °C for 24 h to obtain a pink-white powder, which was recorded as COF-1.

[0030] Example 1

[0031] Cu2O-COF-1 was prepared according to the following procedure: 20 mg of nano-Cu2O powder (50 nm) was mixed with 250 mg (1.5 mmol) of BDBA monomer in a pre-washed and dried 20 mL PYREX test tube. Then 10 mL of mixed solvent (APTES 75.0 mg, 1,4-dioxane 5 mL, toluene 5 mL) was added. The reaction mixture was sonicated for 30 min, and then a three-time degassing process was performed using the cycle of "frozen to solid state-pumping vacuum-nitrogen gas-pumped to liquid state". Then the test tube was flame-sealed, and the mixture was sonicated again for 1 h. Finally, the test tube was kept in a 75 °C oil bath with stirring for 24 h.

[0032] At the end of the reaction, the product was collected (filtered with a Buchner funnel), washed with acetone for 5 h (to wash away the monomer and high-boiling solvent) and filtered, and the washing and filtering steps were repeated three times, and then the Cu2O-COF-1 was obtained as a light pink powder after drying in a 75 °C vacuum oven for 24 h.

[0033] The TEM images of the samples obtained in Comparative Example 1 and Example 1 are shown in Figs. 1 and 2, respectively. As can be seen from the images, the Cu2O-COF-1 sample has Cu2O and COF-1 combined by in-situ growth. Figure 1 、 2

[0034] The bactericidal effect of the obtained sample was tested according to the following procedure:

[0035] a. Preparation before experiment: prepare several 15 mL glass test tubes, several 5 mL glass test tubes, several 1.5 mL centrifuge tubes, lactose cholate fermentation medium (LB), lactose cholate agar fermentation solid medium, PBS buffer, all of which are sterilized by high-pressure steam sterilization (121 °C, 40 min) and ready for use; the lactose cholate agar fermentation solid medium is cooled to 60 °C, poured into a plate, and waits for solidification to form a solid culture dish.

[0036] b. Shake the bacteria: take 15 mL glass test tubes, add 10-12 mL of lactose cholate fermentation medium (LB), inoculate S. aureus or E. coli, and then place in a constant temperature shaker, 37 °C, 160 r / min for 18-20 h, so that the colony count reaches about 5 x 10 8 CFU / mL.

[0037] c. Use a pipette to take 3 μL of the bacterial solution obtained in step b and add it to 4 mL of deionized water, shake well to obtain a bacterial suspension.

[0038] ​d. Take 70 μL of the bacterial suspension obtained in step c and put it into 50 mL of PBS buffer. After mixing, take 30 μL and spread it on a plate as a blank control group. Place the petri dish in a constant temperature incubator for 24 h and record the number of colonies.

[0039] e. Set up two groups: Take 70 μL of the bacterial suspension obtained in step c and put it into 50 mL of PBS buffer, and add 5 mg of the sample Cu2O-COF-1 prepared in Example 1.

[0040] One of the two groups is placed under visible light and stirred at a constant speed, denoted as Light(L); the other group is placed in the dark and stirred at a constant speed, denoted as Dark(D).

[0041] After 10 min, 20 min, and 30 min, 30 μL of the mixed liquid from group D and group L was taken and spread onto plates. The plates were then placed in a constant temperature incubator for 24 h and the colony count was recorded.

[0042] The plate coating results of Cu2O-COF-1 obtained in Example 1 of this invention, after co-culturing with Staphylococcus aureus and Escherichia coli for 30 min under light and dark conditions, are as follows: Figure 3 As shown in the figure, compared with the blank control group (Control) without Cu2O-COF-1, the addition of Cu2O-COF-1 for 30 minutes under dark conditions has a certain antibacterial effect, while the addition of Cu2O-COF-1 under light conditions can kill all bacteria in just 30 minutes.

[0043] The colony counts recorded from the plate coating results were plotted as a line graph. Figure 4 The graphs shown are line graphs comparing the antibacterial rates of Cu2O-COF-1 obtained in Example 1 of this invention against Escherichia coli and Staphylococcus aureus under light (L) and dark (D) conditions. In the figure, a is a line graph comparing the antibacterial rates of Escherichia coli under light (L) and dark (D) conditions, and b is a line graph comparing the antibacterial rates of Staphylococcus aureus under light (L) and dark (D) conditions.

[0044] The bactericidal effect of COF-1 was tested using the same method, and the results of the plate coating were as follows ( Figure 5) shows that COF-1 needs 120 min of light irradiation to kill all E. coli and 150 min of light irradiation to kill all S. aureus under the same conditions. Compared with the antibacterial results of Cu2O-COF-1, it can be seen that Cu2O-COF-1 has higher photocatalytic antibacterial efficiency.

[0045] The laser confocal scanning microscope test results of E. coli and S. aureus of the blank control group (Untreated) and the Cu2O-COF-1 light irradiation group (treated) after treatment are shown in Figure 6 The detection results show that the Cu2O-COF-1 obtained in Example 1 can indeed cause irreversible apoptosis of bacteria under white light irradiation.

[0046] The XRD test results of the sample obtained in Example 1 are shown in Figure 7 The peaks at 6.76°, 11.76°, 14.8°, 19.05°, 26.8°, 36.4°, 42.29°, 61.33° and 73.5° correspond to the 100, 110, 101, 201, 002, 111, 200, 220, 311 and 222 diffraction planes, respectively, indicating the successful synthesis of Cu2O-COF-1.

[0047] The photocurrent response test results of the sample obtained in Example 1 are shown in Figure 8 Theoretically, the stronger the current response of the sample to light, the stronger the active oxygen (ROS) generated, and ROS is the main component of photocatalytic antibacterial. Combined with the antibacterial test results of 3, 4, 5 and 6, it can be seen that the photocatalytic effect is applied to the antibacterial test of simple strains, and good antibacterial effect is obtained. Figure 3 、 4 、

[0048] Obviously, the above examples are only examples for clarity and do not limit the embodiments. Any skilled person in the art can modify or reform the above disclosed technology content into equivalent examples of equivalent changes. However, any simple modification, equivalent change and modification made on the basis of the technical essence of the present application to the above examples still belongs to the protection scope of the present application technical solution.

Claims

1. A method of synthesis of a cuprous oxide-containing covalent organic framework having photobactericidal activity, characterized by: First, the nano Cu2O powder is mixed with 1,4-phenyl boric acid monomer, added into a pre-washed and dried PYREX test tube, and then a mixed solvent composed of APTES, dioxane and toluene is added, the reaction mixture is ultrasonically treated for 30 min, and then a degassing process using the cycle of freezing into solid, vacuumizing, nitrogenizing and thawing into liquid is performed for three times; then the test tube is flame sealed, and the mixture is ultrasonically treated for 1 h again; finally, the test tube is heat preserved and stirred in an oil bath at 75℃ for 24 h; at the end of the reaction, the product is collected by filtering with a Buchner funnel, washed in acetone by ultrasonic for 5 h and filtered, the steps of washing and filtering are repeated for three times, and then the product is dried in a vacuum oven at 60~75℃ for 24~48 h to obtain a cuprous oxide-containing covalent organic framework powder; wherein: the amount ratio of the nano Cu2O powder, 1,4-phenyl boric acid and the mixed solvent is 20~100 mg: 250 mg: 10 mL; in the mixed solvent, the amount ratio of APTES, dioxane and toluene is 75 mg: 5 mL: 5 mL.

2. The method of synthesis of claim 1, wherein: The nano Cu2O powder has a particle size of 50~100 nm. 3.A cuprous oxide-containing covalent organic framework prepared by the synthesis method of any one of claims 1~2. 4.Use of the cuprous oxide-containing covalent organic framework of claim 3 as a photocatalytic antibacterial material.

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