A modified polyvinyl alcohol multifunctional hydrogel and its preparation method and application

Abstract

The present invention relates to a modified polyvinyl alcohol multifunctional hydrogel and a preparation method and application thereof. First, polydopamine is synthesized, then a polyvinyl alcohol / polydopamine dispersion is prepared, and then urea and tannic acid are added for cross-linking reaction, and finally a multifunctional hydrogel product is obtained. The test results show that the hydrogel has multiple functions such as antibacterial, adhesion, antioxidant, anti-swelling, self-healing, photothermal and plasticity, and the photothermal property can also help to further enhance the antibacterial effect of the hydrogel, playing a synergistic role. The preparation method of the present invention is simple and easy to implement. By regulating some process parameters, the various properties of the hydrogel can also be flexibly adjusted, thereby enriching the types and uses of hydrogel products.

Description

Technical Field

[0001] The invention relates to the technical field of biomedical materials, and in particular to a modified polyvinyl alcohol multifunctional hydrogel and a preparation method and application thereof. Background Art

[0002] Hydrogel is a three-dimensional polymer that uses water as a dispersion medium and is cross-linked physically or chemically. It has the properties of both solid and liquid. Due to its soft tissue-like water-containing structure and certain mechanical properties (flexibility and stretchability, etc.), hydrogel has become an ideal material for tissue engineering scaffolds, wound dressings and new drug delivery systems, and is widely used in the biomedical field.

[0003] Functional hydrogels with various structures can be designed and constructed by using chemical modification and composite techniques, such as high-strength hydrogels, antibacterial hydrogels and injectable hydrogels. However, different application environments often require multifunctional hydrogels. Therefore, it is necessary to develop new hydrogel materials with multiple functions.

[0004] Polyvinyl alcohol is a common synthetic polymer obtained by alcoholysis of polyvinyl acetate. Since there are many hydrophilic hydroxyl groups in the molecular chain of polyvinyl alcohol, it is easy to make hydrogel. The specific preparation methods include cyclic freezing-thawing and borax cross-linking. Although the biocompatibility and mechanical properties of polyvinyl alcohol hydrogel are relatively excellent, the molecular structure of polyvinyl alcohol does not contain functional groups, resulting in the hydrogel's antibacterial and adhesion properties being significantly insufficient and unable to meet the requirements of multifunctional applications. Therefore, it is necessary to functionalize it. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems and shortcomings of the prior art and to provide a new modified polyvinyl alcohol multifunctional hydrogel and its preparation method and application. The present invention obtains a modified polyvinyl alcohol multifunctional hydrogel by compounding polyvinyl alcohol, tannic acid, polydopamine and urea, wherein the addition of tannic acid improves the adhesion and antioxidant properties of the hydrogel, and polydopamine simultaneously improves the adhesion, antibacterial and photothermal properties of the hydrogel. To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is as follows:

[0006] A method for preparing a modified polyvinyl alcohol multifunctional hydrogel specifically comprises the following steps: first, synthesizing polydopamine, then preparing a polyvinyl alcohol / polydopamine composite dispersion, and then adding urea and tannic acid to react to obtain the modified polyvinyl alcohol multifunctional hydrogel.

[0007] Furthermore, the mass ratio of polyvinyl alcohol, polydopamine, urea and tannic acid required for the reaction is 1:0.02-0.1:3-15:1.5.

[0008] Furthermore, the synthesis method of polydopamine is as follows: a certain amount of dopamine powder is weighed and added to an ethanol solution, the pH of the mixture is adjusted to 9 with a NaOH solution, the mixture is stirred for 16 hours and then centrifuged, and the obtained solid is dried to obtain polydopamine.

[0009] Furthermore, the preparation method of the polyvinyl alcohol / polydopamine dispersion is as follows: polydopamine and polyvinyl alcohol are put into a container in proportion, deionized water is added and the temperature is raised to 85-95°C, and the mixture is fully stirred at this temperature (about 1-2 hours) to completely dissolve the polyvinyl alcohol and uniformly disperse the polydopamine.

[0010] Furthermore, the mass percentage concentration of polyvinyl alcohol in the polyvinyl alcohol / polydopamine dispersion is 6% to 15%.

[0011] Furthermore, urea in the raw material is introduced in the form of urea aqueous solution. Urea mainly plays a role in regulating the gelation of polyvinyl alcohol and tannic acid. The cross-linking degree of simple polyvinyl alcohol and tannic acid is too tight, which is not conducive to the exposure of polyphenol groups. The appropriate addition of urea can reduce the cross-linking degree of the hydrogel, allowing more polyphenol groups to be exposed, thereby improving the adhesion performance of the hydrogel.

[0012] Furthermore, the mass percent concentration of urea is 37.5%.

[0013] Furthermore, the raw material tannic acid is introduced in the form of a tannic acid aqueous solution.

[0014] Furthermore, the mass percentage concentration of tannic acid is 15%.

[0015] Furthermore, after adding tannic acid, the mixture is stirred and reacted at room temperature for 1 to 5 minutes.

[0016] Another important object of the present invention is to provide a modified polyvinyl alcohol multifunctional hydrogel, which simultaneously exhibits excellent antibacterial, adhesion, antioxidant, anti-swelling, self-healing, photothermal and plasticity properties.

[0017] The third object of the present invention is to provide the application of the modified polyvinyl alcohol multifunctional hydrogel in biomedicine and personal hygiene materials.

[0018] The preparation mechanism of the modified polyvinyl alcohol multifunctional hydrogel of the present invention is as follows: by compounding tannic acid, the cross-linking between the hydrogel and polyvinyl alcohol is made tighter, and more catechol structures are exposed at the same time, thereby significantly enhancing the adhesion performance of the hydrogel, and retaining the original antioxidant and antibacterial properties of tannic acid. The introduction of polydopamine can simultaneously improve the adhesion, antibacterial and photothermal properties of the hydrogel. The hydrogel cross-links polyvinyl alcohol through tannic acid, and urea also participates in the cross-linking, which plays a role in regulating the cross-linking structure. Polydopamine mainly exists in the system in the form of small particles, forming a dual adhesion network structure, that is, the adhesion of tannic acid and polydopamine. These two adhesion effects do not exist independently of each other, but act synergistically, cross-linked together through hydrogen bonding, and polydopamine is also loaded in the hydrogel with hydrogen bonds, which together give the hydrogel multifunctionality.

[0019] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects:

[0020] (1) The hydrogel provided by the present invention has multiple functions such as excellent antibacterial, adhesion, antioxidant, anti-swelling, self-healing, photothermal and plasticity, and can meet application scenarios with high comprehensive performance requirements;

[0021] (2) The hydrogel provided by the present invention adopts pure physical cross-linking without adding chemical cross-linking agents, so it has good biocompatibility;

[0022] (3) The hydrogel provided by the present invention has outstanding adhesion to various objects (such as glass, metal, rubber and skin tissue, etc.);

[0023] (4) With the addition of polydopamine, the adhesion performance of the modified polyvinyl alcohol multifunctional hydrogel provided by the present invention is significantly improved, and it can stably adhere to the skin surface;

[0024] (5) The hydrogel provided by the present invention has good photothermal properties;

[0025] (6) The hydrogel provided by the present invention has good antibacterial properties against Staphylococcus aureus and Escherichia coli. The addition of polydopamine significantly enhances the antibacterial properties, and the photothermal property also helps to further enhance the antibacterial effect of the hydrogel;

[0026] (7) The addition of urea in the present invention can significantly enhance the adhesion properties of the hydrogel;

[0027] (8) The hydrogel provided by the present invention has excellent dual adhesion and dual antibacterial capabilities, which are all derived from the effects of tannic acid, polydopamine and urea;

[0028] (9) The hydrogel provided by the present invention has outstanding anti-swelling properties, small swelling in the application environment, stable structure, and stable adhesion and other properties;

[0029] (10) The hydrogel provided by the present invention has significant antioxidant properties;

[0030] (11) The hydrogel provided by the present invention has good plasticity;

[0031] (12) The hydrogel provided by the present invention has excellent self-healing properties;

[0032] (13) The hydrogel preparation method provided by the present invention is simple and easy to implement, and various properties of the hydrogel can be flexibly adjusted by regulating some process parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the adhesion performance test of modified polyvinyl alcohol multifunctional hydrogel;

[0034] Figure 2 Antibacterial properties of modified polyvinyl alcohol multifunctional hydrogels. DETAILED DESCRIPTION

[0035] In order to enable ordinary technicians in the field to fully understand the technical solutions and beneficial effects of the present invention, further description is given below in conjunction with specific embodiments and drawings.

[0036] Example 1

[0037] 1) Weigh 0.5 g dopamine powder and add it to a mixed solution consisting of 90 mL deionized water and 40 mL ethanol. -1 The pH of the solution was adjusted to 9 with NaOH solution, and the reaction was stirred for 16 hours;

[0038] 2) centrifuging and drying the product of step 1) to obtain polydopamine powder;

[0039] 3) In a 90° C. water bath, add 0.5 g of polyvinyl alcohol and 0.03 g of polydopamine to 4.5 mL of deionized water and stir to obtain a polyvinyl alcohol / polydopamine dispersion;

[0040] 4) Prepare a urea aqueous solution with a mass percentage concentration of 37.5% for standby use;

[0041] 5) taking 2.5 mL of urea aqueous solution, adding it to the polyvinyl alcohol / polydopamine dispersion, and stirring to obtain a polyvinyl alcohol / polydopamine / urea composite dispersion;

[0042] 6) adding 0.75 g of tannic acid into 4.25 mL of deionized water and stirring at room temperature to completely dissolve the tannic acid to obtain a tannic acid solution;

[0043] 7) Slowly adding the tannic acid solution into the polyvinyl alcohol / polydopamine / urea composite dispersion obtained in step 5), stirring and reacting at room temperature for 5 minutes to obtain a modified polyvinyl alcohol multifunctional hydrogel.

[0044] Referring to the single lap tensile shear strength test method of adhesive GB / T 33334-2016, the prepared hydrogel was tested for skin (pig skin) adhesion performance at room temperature, as shown in the schematic diagram Figure 1 . The antioxidant effect of the hydrogel was evaluated by the scavenging rate of 2,2-biphenyl-1-picrylhydrazyl (15 mg hydrogel dosage). The swelling properties of the hydrogel were tested by the weighing method. The antibacterial properties of the hydrogel were studied by the plate counting method. (The same below)

[0045] The test results show that the hydrogel prepared in Example 1 has excellent plasticity, self-healing, photothermal properties (0.3 W power, 808 nm near-infrared light irradiation within 10 minutes, the temperature of the hydrogel rises from 25°C to 60°C), adhesion (49.2 kPa), antioxidant (2,2-biphenyl-1-picrylhydrazyl removal rate is 90.6%), anti-swelling (swelling degree 34.6%), antibacterial (antibacterial rate of Staphylococcus aureus 75.3%, antibacterial rate of Escherichia coli 83.1%) and other multiple properties.

[0046] In addition, Figure 2 As shown in the figure, after irradiating the hydrogel with 808nm near-infrared laser for 10 minutes, the antibacterial rate of both bacteria reached 99.9%. Under the same preparation process conditions, the antibacterial rate of the hydrogel prepared without adding polydopamine (control group) against Staphylococcus aureus was only 51.4%, and the antibacterial rate against Escherichia coli was only 63.4%. This result shows that the introduction of polydopamine significantly improves the antibacterial performance of the hydrogel.

[0047] Example 2

[0048] 1) Weigh 0.5 g dopamine powder and add it to a mixed solution consisting of 90 mL deionized water and 40 mL ethanol. -1 The pH of the solution was adjusted to 9 with NaOH solution, and the reaction was stirred for 16 hours;

[0049] 2) centrifuging and drying the product of step 1) to obtain polydopamine powder;

[0050] 3) In a 90° C. water bath, add 0.5 g of polyvinyl alcohol and 0.03 g of polydopamine to 4.5 mL of deionized water and stir to obtain a polyvinyl alcohol / polydopamine dispersion;

[0051] 4) Prepare a urea aqueous solution with a mass percentage concentration of 37.5% for standby use;

[0052] 5) taking 4.16 mL of urea aqueous solution, adding it to the polyvinyl alcohol / polydopamine dispersion, and stirring to obtain a polyvinyl alcohol / polydopamine / urea composite dispersion;

[0053] 6) adding 0.75 g of tannic acid into 4.25 mL of deionized water and stirring at room temperature to completely dissolve the tannic acid to obtain a tannic acid solution;

[0054] 7) Slowly adding the tannic acid solution into the polyvinyl alcohol / polydopamine / urea composite dispersion obtained in step 5), stirring and reacting at room temperature for 5 minutes to obtain a modified polyvinyl alcohol multifunctional hydrogel.

[0055] The test results show that the anti-swelling, anti-oxidation and adhesion properties of the hydrogel prepared in Example 2 are also outstanding, with a swelling degree of 29.8%, an anti-oxidation of 90.7% (2,2-biphenyl-1-picrylhydrazyl clearance rate), and an adhesion strength of 77.8 kPa to the skin. In addition, it has good adhesion properties to plastics, rubber, stainless steel, glass and paper.

[0056] Example 3

[0057] 1) Weigh 0.5 g dopamine powder and add it to a mixed solution consisting of 90 mL deionized water and 40 mL ethanol. -1 The pH of the solution was adjusted to 9 with NaOH solution, and the reaction was stirred for 16 hours;

[0058] 2) centrifuging and drying the product of step 1) to obtain polydopamine powder;

[0059] 3) In a 90° C. water bath, add 0.5 g of polyvinyl alcohol and 0.02 g of polydopamine to 4.5 mL of deionized water and stir to obtain a polyvinyl alcohol / polydopamine dispersion;

[0060] 4) Prepare a urea aqueous solution with a mass percentage concentration of 37.5% for standby use;

[0061] 5) taking 2.5 mL of urea aqueous solution, adding it to the polyvinyl alcohol / polydopamine dispersion, and stirring to obtain a polyvinyl alcohol / polydopamine / urea composite dispersion;

[0062] 6) adding 0.75 g of tannic acid into 4.25 mL of deionized water and stirring at room temperature to completely dissolve the tannic acid to obtain a tannic acid solution;

[0063] 7) Slowly adding the tannic acid solution into the polyvinyl alcohol / polydopamine / urea composite dispersion obtained in step 5), stirring and reacting at room temperature for 5 minutes to obtain a modified polyvinyl alcohol multifunctional hydrogel.

[0064] The test results show that the swelling degree of the hydrogel prepared in Example 3 is 30%, the anti-oxidation is 90.3% (2,2-biphenyl-1-picrylhydrazyl removal rate), and the adhesion strength of the hydrogel to the skin is 50.1 kPa. The above results show that the hydrogel does have good anti-swelling, anti-oxidation and adhesion properties.

[0065] Example 4

[0066] 1) Weigh 0.5 g dopamine powder and add it to a mixed solution consisting of 90 mL deionized water and 40 mL ethanol. -1 The pH of the solution was adjusted to 9 with NaOH solution, and the reaction was stirred for 16 hours;

[0067] 2) centrifuging and drying the product of step 1) to obtain polydopamine powder;

[0068] 3) In a 90° C. water bath, add 0.3 g of polyvinyl alcohol and 0.03 g of polydopamine to 4.5 mL of deionized water and stir to obtain a polyvinyl alcohol / polydopamine dispersion;

[0069] 4) Prepare a urea aqueous solution with a mass percentage concentration of 37.5% for standby use;

[0070] 5) taking 2.5 mL of urea aqueous solution, adding it to the polyvinyl alcohol / polydopamine dispersion, and stirring to obtain a polyvinyl alcohol / polydopamine / urea composite dispersion;

[0071] 6) adding 0.75 g of tannic acid into 4.25 mL of deionized water and stirring at room temperature to completely dissolve the tannic acid to obtain a tannic acid solution;

[0072] 7) Slowly adding the tannic acid solution into the polyvinyl alcohol / polydopamine / urea composite dispersion obtained in step 5), stirring and reacting at room temperature for 5 minutes to obtain a modified polyvinyl alcohol multifunctional hydrogel.

[0073] The test results show that the swelling degree of the hydrogel prepared in Example 4 is 24.5%, the anti-oxidation is 91.8% (2,2-biphenyl-1-picrylhydrazyl removal rate), and the adhesion strength of the hydrogel to the skin is 32.5 kPa. This result shows that the hydrogel has significant anti-swelling, anti-oxidation and adhesion properties.

Claims

1. A method for preparing a modified polyvinyl alcohol multifunctional hydrogel, characterized in that: The method comprises the following steps: firstly synthesizing polydopamine, then preparing a polyvinyl alcohol-polydopamine dispersion, and then adding urea and tannic acid for reaction; the preparation method of the polyvinyl alcohol-polydopamine dispersion comprises: mixing polydopamine and polyvinyl alcohol in proportion, then adding deionized water, heating the obtained mixture to 85-95°C and then stirring it evenly to obtain the polyvinyl alcohol-polydopamine dispersion, wherein the mass percentage concentration of the polyvinyl alcohol is 6%-15%; the mass ratio of the polyvinyl alcohol, polydopamine, urea and tannic acid is 1:0.02-0.1:3-15:1.

5.

2. The method according to claim 1, characterized in that: The synthesis method of polydopamine comprises: adding dopamine into an ethanol aqueous solution, then adding a NaOH solution to adjust the pH of the solution to 9, stirring the reaction for 16 hours, and then separating and drying.

3. The method according to claim 1, characterized in that: Urea is introduced in the form of urea aqueous solution, and the mass percentage concentration of urea is 37.5%.

4. The method according to claim 1, characterized in that: Tannic acid is introduced in the form of tannic acid aqueous solution, and the mass percentage concentration of tannic acid is 15%. After adding tannic acid, the reaction is stirred at room temperature.

5. A modified polyvinyl alcohol multifunctional hydrogel, characterized in that: The hydrogel is prepared according to any one of the methods of claims 1-4.

6. The modified polyvinyl alcohol multifunctional hydrogel according to claim 5, characterized in that: The hydrogel has a three-dimensional network structure and can adhere to glass, metal, rubber or skin tissue. It also has antibacterial, adhesion, antioxidant, anti-swelling, self-healing, photothermal and plasticity properties.

7. Use of the modified polyvinyl alcohol multifunctional hydrogel according to claim 5 or 6 in the preparation of biomedicine and personal hygiene materials.

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