Preparation method and application of antibacterial agent based on benzimidazolyl Schiff base structure

Abstract

The invention discloses a preparation method and application of an antibacterial agent based on a benzimidazolyl Schiff base structure. The antibacterial agent prepared by utilizing the characteristics of a benzimidazole group and a Schiff base structure not only has antibacterial property, but also has ultraviolet absorption property, and then is compounded with the PVC composite film, so that the prepared PVC composite film has extremely strong antibacterial property and ultraviolet resistance, and the application range of the soft PVC composite film is widened.

Description

Technical Field

[0001] The invention relates to the fields of general plastic modification and organic synthesis, and in particular to a preparation method of an antibacterial agent based on a benzimidazole-based Schiff base structure and application of the antibacterial agent in a PVC composite film. Background Art

[0002] Soft polyvinyl chloride (PVC) is a sealing material widely used in automobiles, refrigerators and other home appliances. However, due to the addition of a large amount of plasticizers and other additives to soft PVC, its surface is very easy to change color or produce mildew under suitable conditions. At the same time, PVC is prone to chain dehydrochlorination reaction under ultraviolet light, discoloration and aging, which not only destroys the appearance of the product, but also significantly reduces the physical properties and service life of the material, and will cause harm to the environment. Therefore, the development of antibacterial, mildew-proof and UV-resistant soft PVC composite materials has always been a hot topic in the research of antibacterial PVC materials.

[0003] Schiff base organic compounds are widely used in the industrial fields of biological and pharmaceutical applications. Among them, aromatic hydrocarbon Schiff bases have good antibacterial effects and high safety. Nitrogen-containing heterocyclic benzimidazoles are the framework of a class of pharmacophores. Benzimidazoles used to develop therapeutic drugs are benzo derivatives of imidazoles. Their fused heterocyclic structures are crucial to the formation of nucleotides. At the same time, benzimidazoles and their derivatives easily interact with biopolymers. At present, the combination of benzimidazole and Schiff bases has not been applied to PVC materials. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a preparation of a benzimidazole-based Schiff base structure antibacterial agent, which is successfully applied to PVC composite film by modifying the Schiff base antibacterial agent with a benzimidazole functional group. According to the antibacterial properties of Schiff base and imidazole groups, the present invention adopts a step-by-step synthesis method to prepare a benzimidazole-based Schiff base structure antibacterial agent, and applies it to PVC composite film.

[0005] To this end, the present invention adopts the following technical solutions: A method for preparing a benzimidazole-based Schiff base structure antibacterial agent, characterized in that it comprises the following steps: 1) Preparation of benzimidazole-based antibacterial agent intermediates: dissolving DOPA and o-phenylenediamine in a hydrochloric acid solution to obtain a mixed solution; 2) The mixed solution is heated and refluxed, cooled to room temperature, adjusted to a neutral pH with aqueous ammonia, filtered, washed and dried to obtain a bright yellow powder; 3) Preparation of a benzimidazole Schiff base structure antibacterial agent, dispersing the bright yellow powder obtained in step 2) and salicylaldehyde in an organic solvent, and stirring at room temperature to dissolve them; 4) Slowly add glacial acetic acid and let stand after the reaction to obtain an emulsion suspension; 5) The excess solvent is removed from the emulsion suspension obtained in step 4) by vacuum evaporation, the residual solution is filtered, and the reaction product is recrystallized by anhydrous ethanol and dried to obtain a light yellow powder product antibacterial agent.

[0006] On the basis of adopting the above technical solution, the present invention can also adopt the following further technical solution, or use the above further technical solution in combination: In step 1), the weighing ratio of DOPA to o-phenylenediamine is 1.5:1 to 2:1, and the concentration of hydrochloric acid is 3 to 5 mol / L, which is controlled to be 10 to 20 times the mass of DOPA.

[0007] In step 3), the weighing ratio of the bright yellow powder and salicylaldehyde is 2.1:1-1.6:1, and the organic solvent is ethanol, and the volume ratio of ethanol to hydrochloric acid solution is 1:1.

[0008] In step 4), the amount of glacial acetic acid added is 0.5% to 1% of the volume of the ethanol solution.

[0009] The solutions prepared in step 1) to step 5) are all prepared and used immediately. If they are to be stored for later use, they need to be stored at 4°C.

[0010] According to the second aspect of the present invention, the present invention also provides the use of the benzimidazole-based Schiff base structure antibacterial agent obtained by the preparation method in the preparation of an antibacterial PVC composite film.

[0011] In the above application, the obtained benzimidazole-based Schiff base structure antibacterial agent is mixed with a plasticizer, a heat stabilizer and PVC resin powder, and stirred at high speed to obtain the PVC slurry of the antibacterial PVC composite film.

[0012] Furthermore, the addition ratio of the antibacterial agent to the PVC resin powder is 1:500 ~ 3:500, the addition ratio of the plasticizer to the heat stabilizer is 40:1 ~ 15:1, the stirring speed is 500 ~1000r / min, and the stirring time is 10~50 min.

[0013] Furthermore, the PVC slurry is prepared and used immediately.

[0014] In the present invention, the antibacterial property of the light yellow powdered antibacterial agent obtained in step 5) is mainly tested by the inhibition zone method. According to the standard "GB / T 20944.1-2007", the antibacterial performance of Staphylococcus aureus (S bacteria) and Escherichia coli (E bacteria) is evaluated by the inhibition zone method. First, pour agar culture medium into a culture dish and solidify it, and then sterilize it under ultraviolet light overnight. Then, the S bacteria and E bacteria diluted to 1.1×106 CFU / mL colony units are evenly spread on the surface of the culture medium. After the culture medium absorbs the bacterial solution and dries for 10 minutes, antibacterial powders of different masses are placed on the culture medium, and then cultured in a constant temperature and humidity chamber at 37°C for 24 hours. Observe the inhibition zone appearing around the culture dish, and qualitatively evaluate the antibacterial effect of the powder according to the size of the inhibition zone.

[0015] In the present invention, the antibacterial property of the antibacterial PVC composite film is mainly tested by the oscillation method. According to the standard "GB / T 31402-2015", the antibacterial properties of the PVC composite film before and after modification were tested. The antibacterial properties of the fabric against Staphylococcus aureus (S bacteria) and Escherichia coli (E bacteria) were evaluated by the oscillation method. First, 1g of PVC composite film was taken, cut into 1 cm×1 cm size, and wrapped in kraft paper. The fabric, liquid culture medium, nutrient agar and glassware were placed in a sterilizing pot for sterilization (120 ℃, 60min). Subsequently, the sterilized fabric was placed in a liquid culture medium with a bacterial concentration of 1.1×105 CFU / mL and cultured in a constant temperature shaker (24 ℃, 150 r / min) for 18h. After the culture was completed, the bacterial solution in the liquid culture medium was diluted to 103 CFU / mL using PBS buffer, and then 100μL of bacterial solution was taken with a pipette and dropped on the solid nutrient agar and evenly spread. The agar culture dish was placed in a constant temperature and humidity chamber at 37°C and cultured for 24 hours, and the live bacteria on the plate were counted.

[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) The benzimidazole-based Schiff base antibacterial agent synthesized in the present invention not only has extremely high antibacterial properties, but also has extremely strong ultraviolet absorption performance, which further improves the commercial value of the product.

[0017] (2) The o-phenylenediamine, dopa and salicylaldehyde used in the present invention are all non-toxic, harmless and environmentally friendly. They are used in small amounts, save resources and are suitable for application in PVC composite films. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram showing the antibacterial effect of the light yellow powder product prepared in Example 1 of the present invention on E bacteria and S bacteria. The left side shows the antibacterial effect on E bacteria, and the right side shows the antibacterial effect on S bacteria.

[0019] Figure 2 This is the antibacterial effect diagram of PVC composite film against E bacteria and S bacteria before and after modification. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the embodiments. Example

[0021] A preparation method of a benzimidazole-based Schiff base structure antibacterial agent and its application in a PVC composite film comprises the following steps: 1) Preparation of benzimidazole-based antibacterial agent intermediate: 10.0 g of DOPA and 5.1 g of o-phenylenediamine were dissolved in 150 mL of hydrochloric acid solution (4 mol / L) to obtain a mixed solution; 2) The mixed solution was refluxed at 80 °C for 4 h, cooled to room temperature, adjusted to pH 7 with aqueous ammonia, filtered, washed with deionized water and vacuum dried to obtain a bright yellow powder; 3) Preparation of a benzimidazole Schiff base structure antibacterial agent: 14.0 g of the bright yellow powder obtained in step 2) and 6.5 g of salicylaldehyde were dispersed in a three-necked flask containing 200 mL of ethanol, and stirred at room temperature for 30 min to dissolve; 4) Slowly add 1 mL of glacial acetic acid to the above mixture through a separatory funnel, stir at 40 °C for 4 h, and then let the reaction mixture stand for 3 h; 5) removing excess solvent from the milky suspension obtained in step 4) by vacuum evaporation, filtering the residual solution, and recrystallizing the reaction product by anhydrous ethanol and drying in an oven for 24 h to obtain a light yellow powder product; 6) subjecting the product obtained in step 5) to an antibacterial test; 7) 0.4 g of the product obtained in step 5) was added to a beaker with 67 g of a plasticizer, 3 g of a heat stabilizer and 100 g of PVC resin powder, and stirred at high speed to obtain a PVC slurry; 8) The PVC slurry was evenly coated on a 20 cm*20 cm glass sheet, and then the glass sheet was placed in a forced air drying oven at 180 °C for 15 min, and a PVC composite film with a thickness of 0.5 mm was prepared after plastic molding; 9) The antibacterial properties of the obtained PVC composite film were tested.

[0022] Among them, step 5) antibacterial activity is mainly tested by the inhibition zone method. The results are shown in Figure 1. According to the GB / T20944.1-2007 standard, the antibacterial performance of Staphylococcus aureus (S bacteria) and Escherichia coli (E bacteria) was evaluated using the inhibition zone method. First, agar culture medium was poured into the culture dish and solidified, and then sterilized under ultraviolet light overnight. Next, S bacteria and E bacteria diluted to 1.1×106 CFU / mL colony units were evenly spread on the surface of the culture medium. After the culture medium absorbed the bacterial solution and dried for 10 minutes, antibacterial powders of different masses were placed on the culture medium and then cultured in a constant temperature and humidity chamber at 37°C for 24 hours. The inhibition zone that appeared around the culture dish was observed, and the antibacterial effect of the powder was qualitatively evaluated according to the size of the inhibition zone.

[0023] Among them, step 9) antibacterial activity is mainly tested by the oscillation method, the results are shown in Figure 2 . According to the GB / T 31402-2015 standard, the antibacterial properties of the PVC composite film before and after modification were tested. The antibacterial properties of the fabric against Staphylococcus aureus (S bacteria) and Escherichia coli (E bacteria) were evaluated by the oscillation method. First, 1g of PVC composite film was cut into 1 cm×1 cm size and wrapped in kraft paper. The fabric, liquid culture medium, nutrient agar and glassware were placed in a sterilizer for sterilization (120 ℃, 60min). Subsequently, the sterilized fabric was placed in a liquid culture medium with a bacterial concentration of 1.1×105 CFU / mL and cultured in a constant temperature shaker (24 ℃, 150 r / min) for 18h. After the culture, the bacterial solution in the liquid culture medium was diluted to 103 CFU / mL using PBS buffer, and then 100μL of bacterial solution was pipetted and dropped on the solid nutrient agar and evenly spread. The agar culture dish was placed in a constant temperature and humidity chamber at 37°C and cultured for 24 hours, and the live bacteria on the plate were counted. Example

[0024] A preparation method of a benzimidazole-based Schiff base structure antibacterial agent and its application in a PVC composite film comprises the following steps: 1) Preparation of benzimidazole-based antibacterial agent intermediate: 10.0 g of DOPA and 5.1 g of o-phenylenediamine were dissolved in 150 mL of hydrochloric acid solution (4 mol / L) to obtain a mixed solution; 2) The mixed solution was refluxed at 80 °C for 4 h, cooled to room temperature, adjusted to pH 7 with aqueous ammonia, filtered, washed with deionized water and vacuum dried to obtain a bright yellow powder; 3) Preparation of a benzimidazole Schiff base structure antibacterial agent: 14.0 g of the bright yellow powder obtained in step 2) and 6.5 g of salicylaldehyde were dispersed in a three-necked flask containing 200 mL of ethanol, and stirred at room temperature for 30 min to dissolve; 4) Slowly add 1 mL of glacial acetic acid to the above mixture through a separatory funnel, stir at 40 °C for 4 h, and then let the reaction mixture stand for 3 h; 5) removing excess solvent from the milky suspension obtained in step 4) by vacuum evaporation, filtering the residual solution, and recrystallizing the reaction product by anhydrous ethanol and drying in an oven for 24 h to obtain a light yellow powder product; 6) subjecting the product obtained in step 5) to an antibacterial test; 7) Add 67g plasticizer, 3g heat stabilizer and 100g PVC resin powder into a beaker and stir at high speed to obtain PVC slurry; 8) The PVC slurry was evenly coated on a 20 cm*20 cm glass sheet, and then the glass sheet was placed in a forced air drying oven at 180 °C for 15 min, and a PVC composite film with a thickness of 0.5 mm was prepared after plastic molding; 9) The antibacterial properties of the obtained PVC composite film were tested.

[0025] Among them, step 9) antibacterial property is mainly tested by oscillation method. According to GB / T 31402-2015 standard, the antibacterial properties of PVC composite films before and after modification were tested. The antibacterial properties of fabrics against Staphylococcus aureus (S bacteria) and Escherichia coli (E bacteria) were evaluated by oscillation method. First, 1g PVC composite film was taken, cut into 1 cm × 1 cm size, and wrapped in kraft paper. The fabric, liquid culture medium, nutrient agar and glassware were placed in a sterilizer for sterilization (120 ℃, 60min). Subsequently, the sterilized fabric was placed in a liquid culture medium with a bacterial concentration of 1.1×105 CFU / mL and cultured in a constant temperature shaker (24 ℃, 150 r / min) for 18h. After the culture, the bacterial solution in the liquid culture medium was diluted to 103 CFU / mL using PBS buffer, and then 100μL of bacterial solution was pipetted and dropped on solid nutrient agar and evenly spread. The agar culture dish was placed in a constant temperature and humidity chamber at 37°C and cultured for 24 hours, and the live bacteria on the plate were counted. Example

[0026] A preparation method of a benzimidazole-based Schiff base structure antibacterial agent and its application in a PVC composite film comprises the following steps: 1) Preparation of benzimidazole-based antibacterial agent intermediate: 10.0 g of DOPA and 5.1 g of o-phenylenediamine were dissolved in 150 mL of hydrochloric acid solution (4 mol / L) to obtain a mixed solution; 2) The mixed solution was refluxed at 80 °C for 4 h, cooled to room temperature, adjusted to pH 7 with aqueous ammonia, filtered, washed with deionized water and vacuum dried to obtain a bright yellow powder; 3) Preparation of a benzimidazole Schiff base structure antibacterial agent: 14.0 g of the bright yellow powder obtained in step 2) and 6.5 g of salicylaldehyde were dispersed in a three-necked flask containing 200 mL of ethanol, and stirred at room temperature for 30 min to dissolve; 4) Slowly add 1 mL of glacial acetic acid to the above mixture through a separatory funnel, stir at 40 °C for 4 h, and then let the reaction mixture stand for 3 h; 5) removing excess solvent from the milky suspension obtained in step 4) by vacuum evaporation, filtering the residual solution, and recrystallizing the reaction product by anhydrous ethanol and drying in an oven for 24 h to obtain a light yellow powder product; 6) subjecting the product obtained in step 5) to an antibacterial test; 7) 0.6 g of the product obtained in step 5) was added to a beaker with 67 g of a plasticizer, 3 g of a heat stabilizer and 100 g of PVC resin powder, and stirred at high speed to obtain a PVC slurry; 8) The PVC slurry was evenly coated on a 20 cm*20 cm glass sheet, and then the glass sheet was placed in a forced air drying oven at 180 °C for 15 min, and a PVC composite film with a thickness of 0.5 mm was prepared after plastic molding; 9) The antibacterial properties of the obtained PVC composite film were tested.

[0027] Among them, step 9) antibacterial property is mainly tested by oscillation method. According to GB / T 31402-2015 standard, the antibacterial properties of PVC composite films before and after modification were tested. The antibacterial properties of fabrics against Staphylococcus aureus (S bacteria) and Escherichia coli (E bacteria) were evaluated by oscillation method. First, 1g PVC composite film was taken, cut into 1 cm × 1 cm size, and wrapped in kraft paper. The fabric, liquid culture medium, nutrient agar and glassware were placed in a sterilizer for sterilization (120 ℃, 60min). Subsequently, the sterilized fabric was placed in a liquid culture medium with a bacterial concentration of 1.1×105 CFU / mL and cultured in a constant temperature shaker (24 ℃, 150 r / min) for 18h. After the culture, the bacterial solution in the liquid culture medium was diluted to 103 CFU / mL using PBS buffer, and then 100μL of bacterial solution was pipetted and dropped on solid nutrient agar and evenly spread. The agar culture dish was placed in a constant temperature and humidity chamber at 37°C and cultured for 24 hours, and the live bacteria on the plate were counted.

[0028] As can be seen from Figure 1, there are obvious antibacterial zones around the BS powder, indicating that the BS powder has a good antibacterial effect on both E and S bacteria.

[0029] Figure 2The figure shows the antibacterial effect of PVC composite film on E bacteria and S bacteria before and after modification, showing the number of E bacteria and S colonies on LB solid culture medium. As shown in the figure, the antibacterial rate of unmodified PVC composite film on E bacteria and S bacteria is only 21.7% and 29.4%, which basically has no antibacterial property. The antibacterial rate of E bacteria and S bacteria of PVC composite film with 0.4g BS powder added is as high as 82.7% and 92.4%, respectively, and the antibacterial rate of E bacteria and S bacteria of PVC composite film with 0.6g BS powder added is as high as 99.3% and 94.1%, respectively, indicating that the addition of BSC powder improves the antibacterial properties of PVC composite film. It further proves that BSC powder inhibits the growth of E bacteria and S bacteria, confirming that BS powder plays a major role in the antibacterial activity of PVC composite film.

[0030] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0031] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing an antibacterial agent based on a benzimidazole Schiff base structure, characterized in that: The following steps are involved: 1) Preparation of benzimidazole-based antibacterial agent intermediates: dissolving DOPA and o-phenylenediamine in a hydrochloric acid solution to obtain a mixed solution; 2) The mixed solution is heated and refluxed, cooled to room temperature, adjusted to a neutral pH with aqueous ammonia, filtered, washed and dried to obtain a bright yellow powder; 3) Preparation of a benzimidazole Schiff base structure antibacterial agent, dispersing the bright yellow powder obtained in step 2) and salicylaldehyde in an organic solvent, and stirring at room temperature to dissolve them; 4) Slowly add glacial acetic acid and let stand after the reaction to obtain an emulsion suspension; 5) The excess solvent is removed from the emulsion suspension obtained in step 4) by vacuum evaporation, the residual solution is filtered, and the reaction product is recrystallized by anhydrous ethanol and dried to obtain a light yellow powder product antibacterial agent.

2. The method for preparing a benzimidazole-based Schiff base structure antibacterial agent according to claim 1, characterized in that: In step 1), the weighing ratio of DOPA and o-phenylenediamine is 1.5:1 to 2:1, the concentration of hydrochloric acid is 3 to 5 mol / L, and the added amount is controlled to be 10 to 20 times the mass of DOPA.

3. The method for preparing a benzimidazole-based Schiff base structure antibacterial agent according to claim 1, characterized in that: In step 3), the weighing ratio of the bright yellow powder and salicylaldehyde is 2.1:1-1.6:1, and the organic solvent is ethanol, and the volume ratio of ethanol to hydrochloric acid solution is 1:

1.

4. A method for preparing a benzimidazole-based Schiff base structure antibacterial agent according to claim 3, characterized in that: In step 4), the amount of glacial acetic acid added is 0.5% to 1% of the volume of the ethanol solution.

5. A method for preparing a benzimidazole-based Schiff base structure antibacterial agent according to claim 1, 2, 3 or 4, characterized in that: The solutions prepared in step 1) to step 5) are all prepared and used immediately.

6. Use of the benzimidazole-based Schiff base structure antibacterial agent obtained by the preparation method according to claim 1, 2, 3 or 4 in the preparation of antibacterial PVC composite film.

7. The use according to claim 6, characterized in that The benzimidazole-based Schiff base structure antibacterial agent obtained by the preparation method of claim 1, 2, 3 or 4 is mixed with a plasticizer, a heat stabilizer and PVC resin powder, and stirred at high speed to obtain the PVC slurry of the antibacterial PVC composite film.

8. The use according to claim 7, characterized in that The adding ratio of antibacterial agent to PVC resin powder is 1:500 ~3:500, the adding ratio of plasticizer and heat stabilizer is 40:1 ~ 15:1, the stirring speed is 500 ~1000r / min, and the stirring time is 10~50 min.

9. The use according to claim 7, characterized in that The PVC slurry is prepared and used immediately.

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