CN111558081A - Tannic acid modified double-layer hydrogel and preparation method thereof - Google Patents
Tannic acid modified double-layer hydrogel and preparation method thereof Download PDFInfo
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- A61L26/00—Chemical aspects of, or use of materials for, wound dressings or bandages in liquid, gel or powder form
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- A61L26/00—Chemical aspects of, or use of materials for, wound dressings or bandages in liquid, gel or powder form
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Abstract
The invention discloses tannic acid modified double-layer hydrogel and a preparation method thereof, wherein the pore diameter of the upper surface of the tannic acid modified double-layer hydrogel is 1-30 mu m, and the pore diameter of the lower surface of the tannic acid modified double-layer hydrogel is 50-300 mu m. The preparation method comprises the steps of soaking the double-layer hydrogel in a tannic acid solution for 1-48 h under a dark condition, and then carrying out ultrasonic oscillation to obtain the tannic acid modified double-layer hydrogel. The tannic acid modified double-layer hydrogel disclosed by the invention is more compact in structure, has good skin adhesiveness, can be quickly restored to the original shape when being mechanically damaged, has good self-healing and performance, can effectively block bacteria, preserve moisture, absorb seepage, prevent falling off and oxidation and promote wound healing, does not damage the skin when being removed from a skin joint, and can reduce treatment and nursing procedures.
Description
Technical Field
The invention belongs to the technical field of biomedical materials, and particularly relates to tannic acid modified double-layer hydrogel and a preparation method thereof.
Background
The hydrogel is a soft material with soft texture and water holding capacity, and is widely applied in the medical field. Porous hydrogels have good water absorption properties, which have potential for use as wound dressings. At present, clinically, the hydrogel dressing generally has a single function, and can not simultaneously meet the requirements of the wound dressing for absorbing seepage, ventilating, preventing the excessive rapid loss of water, keeping the wound surface moist, clearing free radicals and preventing bacterial infection; the wound dressing is easy to damage and cannot be applied to dressing change frequency, and the exudate is exposed only to cause that the wound is difficult to heal; poor adhesion, causing skin health problems around the wound; poor convenience and the like, and influences the popularization and application of the hydrogel dressing in clinical medicine.
The functions of absorbing the exudate and maintaining water for a long time and preventing bacterial infection are contradictory, because the hydrogel needs to have a large pore size for absorbing the exudate and a small pore size for preventing bacteria. In order to balance the liquid absorption and seepage functions of hydrogel materials and prevent bacteria, researchers in the prior art have constructed double-layer hydrogel, namely a second layer of hydrogel is prepared on the surface of a first layer of hydrogel in situ, and meanwhile, liquid absorption, bacterial invasion prevention and rapid water dissipation are realized, but the double-layer hydrogel has the defects that the double-layer hydrogel is difficult to adhere to the skin and cannot be restored when mechanical damage is received. The adhesive and self-healing performance of the hydrogel dressing are improved on the basis of further optimizing the water retention and bacterium resistance performance of the hydrogel dressing, and the hydrogel dressing is one of effective ways for improving the application range of the hydrogel dressing.
Disclosure of Invention
The invention aims to solve the technical problem of providing a tannic acid modified double-layer hydrogel and a preparation method thereof aiming at the defects of the prior art. The tannic acid modified double-layer hydrogel is more compact in structure, has enhanced bacteria-blocking and water-retaining performances, has good skin adhesiveness and self-healing and performance, can quickly recover when being damaged by machinery, and can effectively block bacteria, retain moisture, absorb seepage, prevent falling, resist oxidation and promote wound healing.
In order to solve the technical problems, the invention adopts the technical scheme that: the tannin-modified double-layer hydrogel is characterized in that the aperture of the upper surface of the tannin-modified double-layer hydrogel is 1-30 microns, and the aperture of the lower surface of the tannin-modified double-layer hydrogel is 50-300 microns.
The tannin-modified double-layer hydrogel is characterized in that the pore diameter of the upper surface of the tannin-modified double-layer hydrogel is 1-10 mu m, and the pore diameter of the lower surface of the tannin-modified double-layer hydrogel is 70-120 mu m.
In addition, the invention also provides a method for preparing the tannic acid modified double-layer hydrogel, which is characterized by comprising the steps of soaking the double-layer hydrogel in a tannic acid solution for 1-48 hours under the condition of keeping out of the sun, and then carrying out ultrasonic oscillation to obtain the tannic acid modified double-layer hydrogel.
The method is characterized in that the mass percentage of the tannic acid in the tannic acid solution is 1-50%.
The method is characterized in that the soaking time is 3-12 hours.
The method is characterized in that the preparation method of the double-layer hydrogel comprises the following steps:
mixing a chitosan aqueous solution and a polyvinyl alcohol aqueous solution to obtain a chitosan-polyvinyl alcohol mixed solution;
step two, dissolving polyethylene glycol into the chitosan-polyvinyl alcohol mixed solution in the step one to obtain a hydrogel preparation solution;
step three, pouring the hydrogel preparation liquid obtained in the step two into a template for circulating low-temperature freezing to obtain an upper layer of the double-layer hydrogel;
step four, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution;
step five, dissolving polyethylene glycol into the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step four to obtain hydrogel preparation solution;
and step six, pouring the hydrogel preparation liquid obtained in the step five onto the upper layer of the double-layer hydrogel obtained in the step three at room temperature, and performing circulating low-temperature freezing to obtain the double-layer hydrogel.
The method is characterized in that the mass percentage of the chitosan in the chitosan aqueous solution in the step one is 4-20%; step one, the mass percentage of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10-30%; step one, the temperature of the chitosan-polyvinyl alcohol mixed solution is 70-100 ℃; fourthly, the mass percentage content of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 0.1-4%, and the mass percentage content of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10-30%; fourthly, the temperature of the sodium hyaluronate-polyvinyl alcohol mixed solution is 70-100 ℃.
The method is characterized in that the number average molecular weight of the polyethylene glycol in the step two is 400-4000; in the hydrogel preparation liquid in the second step, the mass percentage of the polyethylene glycol is 5-15%; the number average molecular weight of the polyethylene glycol in the step five is 1500-3000, and in the hydrogel preparation liquid in the step five, the mass percentage of the polyethylene glycol is 5% -10%.
The method is characterized in that the circulation low-temperature freezing in the step three is performed for 2 to 4 times, each circulation low-temperature freezing comprises low-temperature freezing and unfreezing, the low-temperature freezing temperature is-10 to-40 ℃, the low-temperature freezing time is 2 to 40 hours, the unfreezing temperature is 20 to 40 ℃, and the unfreezing time is 2 to 10 hours; and sixthly, the circulation low-temperature freezing is performed for 2-3 times, each circulation low-temperature freezing comprises low-temperature freezing and unfreezing, the low-temperature freezing temperature is-10 ℃ to-40 ℃, the low-temperature freezing time is 2h to 40h, the unfreezing temperature is 20 ℃ to 40 ℃, and the unfreezing time is 2h to 10 h.
The method is characterized by further comprising the step of placing the hydrogel preparation liquid in the step two in a room temperature environment for 10min to 30min and the step five of placing the hydrogel preparation liquid in the room temperature environment for 5min to 20 min.
Compared with the prior art, the invention has the following advantages:
1. the tannic acid modified double-layer hydrogel disclosed by the invention is more compact in structure, has good skin adhesion and self-healing and performance, can quickly recover to an original state when being mechanically damaged, and can effectively inhibit bacteria, preserve moisture, absorb seepage, prevent falling off, resist oxidation and promote wound healing. When the tannin modified double-layer hydrogel is removed from the skin joint, the skin is not damaged, and treatment and nursing processes can be reduced.
2. According to the method, the tannic acid is used as the modified particle, the double-layer hydrogel is soaked in the tannic acid for modification under the condition of keeping out of the sun, and the aperture is adjusted, so that the bacterium-resistant effect and the water retention performance can be improved.
3. Preferably, the double-layer hydrogel is prepared by adopting two-time circulation low-temperature freezing, a chemical cross-linking agent is not required to be introduced, the double-layer hydrogel is safe, non-toxic and convenient, and molecules between the two layers of hydrogel form hydrogen bonds and are tightly combined.
The technical solution of the present invention is further described in detail below with reference to the embodiments and the accompanying drawings.
Drawings
FIG. 1 is a scanning electron micrograph of the upper surface of a bilayer hydrogel in example 1;
FIG. 2 is a scanning electron micrograph of the upper surface of the tannic acid-modified bilayer hydrogel of example 1;
FIG. 3 is a scanning electron micrograph of the lower surface of the bilayer hydrogel of example 1;
FIG. 4 is a scanning electron micrograph of the lower surface of the tannic acid-modified bilayer hydrogel of example 1;
FIG. 5 is a scanning electron micrograph of a cross-section of the tannic acid-modified bilayer hydrogel of example 1 at X50 magnification;
FIG. 6 is a scanning electron micrograph of a cross-section of a tannic acid-modified bilayer hydrogel of example 1 at X95 magnification;
FIG. 7 is a graph showing the antibacterial activity of the tannic acid-modified double-layer hydrogel of example 1;
FIG. 8 is a graph comparing the moisturizing performance of the tannic acid-modified bilayer hydrogel of example 1;
FIG. 9 is a comparative bacteriostatic plot of tannin-modified bilayer hydrogel versus bilayer hydrogel of example 1;
FIG. 10 is a graph of the adhesion performance of the tannic acid-modified bilayer hydrogel of example 1;
FIG. 11 is a graph of the tannin modified bilayer hydrogel self-healing and performance of example 1;
FIG. 12 is a scanning electron micrograph of the tannic acid-modified bilayer hydrogel of example 1 after self-healing;
FIG. 13 is a graph of the antioxidant capacity (ABTS) of the tannic acid-modified bilayer hydrogel of example 1;
FIG. 14 is a graph of the antioxidant properties (DPPH) of the tannin-modified bilayer hydrogel of example 1.
Detailed Description
In the following description, the part directly contacting the skin surface of the human body is referred to as the upper layer of the double-layered hydrogel, and the part away from the skin of the human body is referred to as the lower layer of the double-layered hydrogel. The upper surface of the tannic acid-modified bilayer hydrogel refers to the upper surface of the upper layer of the tannic acid-modified bilayer hydrogel, and the lower surface refers to the lower surface of the lower layer of the tannic acid-modified bilayer hydrogel. In the following description, the room temperature is in the range of 20 ℃ to 25 ℃.
Example 1
The preparation method of the tannic acid modified double-layer hydrogel of the embodiment comprises the following steps:
dissolving water-soluble chitosan in water to obtain a chitosan aqueous solution, and dissolving polyvinyl alcohol in water at 80 ℃ to obtain a polyvinyl alcohol aqueous solution; the number average molecular weight of the polyvinyl alcohol is 80000; the mass percentage of the chitosan in the chitosan aqueous solution is 4%; the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 24%;
step two, mixing the chitosan aqueous solution and the polyvinyl alcohol aqueous solution in the step one according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 80 ℃ to obtain a chitosan-polyvinyl alcohol mixed solution;
step three, completely dissolving powdered polyethylene glycol in the chitosan-polyvinyl alcohol mixed solution in the step two until the solution is clear, so as to obtain a hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 3000; in the hydrogel preparation solution, the mass percentage of polyethylene glycol is 15%;
step four, placing the hydrogel preparation liquid obtained in the step three in a room temperature environment for 10min, pouring the hydrogel preparation liquid into a template, and circularly freezing the template filled with the hydrogel preparation liquid at low temperature to obtain an upper layer of the double-layer hydrogel; the number of times of circulating low-temperature freezing is 3, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 3 times, wherein the temperature of the low-temperature freezing is-20 ℃, the time of the low-temperature freezing is 2 hours, the temperature of the thawing is 25 ℃, and the time of the thawing is 2 hours;
dissolving sodium hyaluronate in water to obtain a sodium hyaluronate aqueous solution, and dissolving polyvinyl alcohol in water at 80 ℃ to obtain a polyvinyl alcohol aqueous solution; the mass percentage content of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 0.8%, and the mass percentage content of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 28%;
step six, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution in the step five according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 80 ℃ to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution; the number average molecular weight of the polyvinyl alcohol is 80000;
step seven, completely dissolving powdered polyethylene glycol in the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step six until the solution is clear to obtain hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 1500, and the mass percentage of the polyethylene glycol in the hydrogel preparation liquid is 8%;
placing the hydrogel preparation liquid obtained in the step seven in a room temperature environment for 5min, placing the upper layer of the double-layer hydrogel obtained in the step four in a template, pouring the placed hydrogel preparation liquid onto the upper layer of the double-layer hydrogel at room temperature, and adding the hydrogel preparation liquid until the height is 2 times of the thickness of the upper layer of the double-layer hydrogel; then, performing circulating low-temperature freezing to obtain double-layer hydrogel; the number of times of circulating low-temperature freezing is 2, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 2 times, wherein the low-temperature freezing temperature is-10 ℃, the low-temperature freezing time is 40 hours, the thawing temperature is 25 ℃, and the thawing time is 2 hours;
step nine, soaking the double-layer hydrogel obtained in the step eight in a tannic acid solution for 3 hours under a dark condition, filtering to obtain a tannic acid soaked double-layer hydrogel, and removing redundant tannic acid on the surface of the double-layer hydrogel after soaking the tannic acid in ultrasonic oscillation to obtain a tannic acid modified double-layer hydrogel; the dosage of the tannic acid solution is based on immersing the double-layer hydrogel, and the volume of the tannic acid solution in the embodiment is 120 mL; in the tannic acid solution, the mass percentage of tannic acid is 10%.
The tannic acid modified double-layer hydrogel obtained in the embodiment has the pore diameter of 1-10 μm on the upper surface and the pore diameter of 70-120 μm on the lower surface. The tannic acid modified double-layer hydrogel in the embodiment has the advantages that the pore diameter of the upper layer is small, the structure is compact, the pore diameter of the lower layer is large, the structure is loose, the two layers are combined tightly, and the two layers are connected seamlessly.
Example 2
The preparation method of the tannic acid modified double-layer hydrogel of the embodiment comprises the following steps:
dissolving water-soluble chitosan in water to obtain a chitosan aqueous solution, and dissolving polyvinyl alcohol in water at 70 ℃ to obtain a polyvinyl alcohol aqueous solution; the polyvinyl alcohol has a number average molecular weight of 150000; the mass percentage of the chitosan in the chitosan aqueous solution is 20%; the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 24%;
step two, mixing the chitosan aqueous solution and the polyvinyl alcohol aqueous solution in the step one according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 70 ℃ to obtain a chitosan-polyvinyl alcohol mixed solution;
step three, completely dissolving powdered polyethylene glycol in the chitosan-polyvinyl alcohol mixed solution in the step two until the solution is clear, so as to obtain a hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 400; in the hydrogel preparation solution, the mass percentage of polyethylene glycol is 5%;
step four, placing the hydrogel preparation liquid obtained in the step three in a room temperature environment for 10min, pouring the hydrogel preparation liquid into a template, and circularly freezing the template filled with the hydrogel preparation liquid at low temperature to obtain an upper layer of the double-layer hydrogel; the number of times of circulating low-temperature freezing is 4, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 4 times, wherein the temperature of the low-temperature freezing is-40 ℃, the time of the low-temperature freezing is 40 hours, the temperature of the thawing is 20 ℃, and the time of the thawing is 2 hours;
dissolving sodium hyaluronate in water to obtain a sodium hyaluronate aqueous solution, and dissolving polyvinyl alcohol in water at 100 ℃ to obtain a polyvinyl alcohol aqueous solution; the mass percentage of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 4%, and the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 30%;
step six, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution in the step five according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 100 ℃ to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution; the polyvinyl alcohol has a number average molecular weight of 150000;
step seven, completely dissolving powdered polyethylene glycol in the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step six until the solution is clear to obtain hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 1500, and the mass percentage of the polyethylene glycol in the hydrogel preparation liquid is 10%;
placing the hydrogel preparation liquid obtained in the step seven in a room temperature environment for 10min, placing the upper layer of the double-layer hydrogel obtained in the step four in a template, pouring the placed hydrogel preparation liquid onto the upper layer of the double-layer hydrogel at room temperature, and adding the hydrogel preparation liquid until the height is 2 times of the thickness of the upper layer of the double-layer hydrogel; then, performing circulating low-temperature freezing to obtain double-layer hydrogel; the number of times of circulating low-temperature freezing is 3, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 3 times, wherein the temperature of the low-temperature freezing is-20 ℃, the time of the low-temperature freezing is 2 hours, the temperature of the thawing is 20 ℃, and the time of the thawing is 4 hours;
step nine, soaking the double-layer hydrogel obtained in the step eight in a tannic acid solution for 8 hours under a dark condition, filtering to obtain a tannic acid soaked double-layer hydrogel, and removing redundant tannic acid on the surface of the double-layer hydrogel after soaking the tannic acid in ultrasonic oscillation to obtain a tannic acid modified double-layer hydrogel; the dosage of the tannic acid solution is based on immersing the double-layer hydrogel, and the volume of the tannic acid solution in the embodiment is 100 mL; in the tannic acid solution, the mass percentage of tannic acid is 25%.
The tannic acid modified double-layer hydrogel obtained in the embodiment has the pore diameter of 1-10 μm on the upper surface and the pore diameter of 70-120 μm on the lower surface. The tannic acid modified double-layer hydrogel in the embodiment has the advantages that the pore diameter of the upper layer is small, the structure is compact, the pore diameter of the lower layer is large, the structure is loose, the two layers are combined tightly, and the two layers are connected seamlessly.
Example 3
The preparation method of the tannic acid modified double-layer hydrogel of the embodiment comprises the following steps:
dissolving water-soluble chitosan in water to obtain a chitosan aqueous solution, and dissolving polyvinyl alcohol in water at 80 ℃ to obtain a polyvinyl alcohol aqueous solution; the number average molecular weight of the polyvinyl alcohol is 60000; the mass percentage of chitosan in the chitosan aqueous solution is 10%; the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 30 percent;
step two, mixing the chitosan aqueous solution and the polyvinyl alcohol aqueous solution in the step one according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 80 ℃ to obtain a chitosan-polyvinyl alcohol mixed solution;
step three, completely dissolving powdered polyethylene glycol in the chitosan-polyvinyl alcohol mixed solution in the step two until the solution is clear, so as to obtain a hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 3000; in the hydrogel preparation solution, the mass percentage of polyethylene glycol is 6%;
step four, placing the hydrogel preparation liquid obtained in the step three in a room temperature environment for 30min, pouring the hydrogel preparation liquid into a template, and circularly freezing the template filled with the hydrogel preparation liquid at low temperature to obtain an upper layer of the double-layer hydrogel; the number of times of circulating low-temperature freezing is 3, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 3 times, wherein the temperature of the low-temperature freezing is-22 ℃, the time of the low-temperature freezing is 6 hours, the temperature of the thawing is 30 ℃, and the time of the thawing is 10 hours;
dissolving sodium hyaluronate in water to obtain a sodium hyaluronate aqueous solution, and dissolving polyvinyl alcohol in water at 80 ℃ to obtain a polyvinyl alcohol aqueous solution; the mass percentage of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 2%, and the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10%;
step six, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution in the step five according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 80 ℃ to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution; the number average molecular weight of the polyvinyl alcohol is 60000;
step seven, completely dissolving powdered polyethylene glycol in the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step six until the solution is clear to obtain hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 2000, and the mass percentage of the polyethylene glycol in the hydrogel preparation liquid is 8%;
placing the hydrogel preparation liquid obtained in the step seven in a room temperature environment for 10min, placing the upper layer of the double-layer hydrogel obtained in the step four in a template, pouring the placed hydrogel preparation liquid onto the upper layer of the double-layer hydrogel at room temperature, and adding the hydrogel preparation liquid until the height is 2 times of the thickness of the upper layer of the double-layer hydrogel; then, performing circulating low-temperature freezing to obtain double-layer hydrogel; the number of times of circulating low-temperature freezing is 2, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 2 times, wherein the temperature of the low-temperature freezing is-20 ℃, the time of the low-temperature freezing is 18 hours, the temperature of the thawing is 30 ℃, and the time of the thawing is 8 hours;
step nine, soaking the double-layer hydrogel obtained in the step eight in a tannic acid solution for 12 hours under a dark condition, filtering to obtain a tannic acid soaked double-layer hydrogel, and removing redundant tannic acid on the surface of the double-layer hydrogel after soaking the tannic acid in ultrasonic oscillation to obtain a tannic acid modified double-layer hydrogel; the dosage of the tannic acid solution is based on immersing the double-layer hydrogel, and the volume of the tannic acid solution in the embodiment is 120 mL; in the tannic acid solution, the mass percentage of tannic acid is 15%.
The tannic acid modified double-layer hydrogel obtained in the embodiment has the pore diameter of 1-10 μm on the upper surface and the pore diameter of 70-120 μm on the lower surface. The tannic acid modified double-layer hydrogel in the embodiment has the advantages that the pore diameter of the upper layer is small, the structure is compact, the pore diameter of the lower layer is large, the structure is loose, the two layers are combined tightly, and the two layers are connected seamlessly.
Example 4
The preparation method of the tannic acid modified double-layer hydrogel of the embodiment comprises the following steps:
dissolving water-soluble chitosan in water to obtain a chitosan aqueous solution, and dissolving polyvinyl alcohol in water at 80 ℃ to obtain a polyvinyl alcohol aqueous solution; the polyvinyl alcohol has a number average molecular weight of 95000; the mass percentage of the chitosan in the chitosan aqueous solution is 6 percent; the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 24%;
step two, mixing the chitosan aqueous solution and the polyvinyl alcohol aqueous solution in the step one according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 80 ℃ to obtain a chitosan-polyvinyl alcohol mixed solution;
step three, completely dissolving powdered polyethylene glycol in the chitosan-polyvinyl alcohol mixed solution in the step two until the solution is clear, so as to obtain a hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 2000; in the hydrogel preparation solution, the mass percentage of polyethylene glycol is 8.3%;
step four, placing the hydrogel preparation liquid obtained in the step three in a room temperature environment for 30min, pouring the hydrogel preparation liquid into a template, and circularly freezing the template filled with the hydrogel preparation liquid at low temperature to obtain an upper layer of the double-layer hydrogel; the number of times of circulating low-temperature freezing is 3, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 3 times, wherein the temperature of the low-temperature freezing is-20 ℃, the time of the low-temperature freezing is 12 hours, the temperature of the thawing is 25 ℃, and the time of the thawing is 4 hours;
dissolving sodium hyaluronate in water to obtain a sodium hyaluronate aqueous solution, and dissolving polyvinyl alcohol in water at 90 ℃ to obtain a polyvinyl alcohol aqueous solution; the mass percentage of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 0.1%, and the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 20%;
step six, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution in the step five according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 90 ℃ to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution; the polyvinyl alcohol has a number average molecular weight of 95000;
step seven, completely dissolving powdered polyethylene glycol in the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step six until the solution is clear to obtain hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 1500, and the mass percentage of the polyethylene glycol in the hydrogel preparation liquid is 7.5%;
placing the hydrogel preparation liquid obtained in the step seven in a room temperature environment for 10min, placing the upper layer of the double-layer hydrogel obtained in the step four in a template, pouring the placed hydrogel preparation liquid onto the upper layer of the double-layer hydrogel at room temperature, and adding the hydrogel preparation liquid until the height is 2 times of the thickness of the upper layer of the double-layer hydrogel; then, performing circulating low-temperature freezing to obtain double-layer hydrogel; the number of times of circulating low-temperature freezing is 2, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 2 times, wherein the temperature of the low-temperature freezing is-20 ℃, the time of the low-temperature freezing is 18 hours, the temperature of the thawing is 25 ℃, and the time of the thawing is 4 hours;
step nine, soaking the double-layer hydrogel obtained in the step eight in a tannic acid solution for 5 hours under a dark condition, filtering to obtain a tannic acid soaked double-layer hydrogel, and removing redundant tannic acid on the surface of the double-layer hydrogel after soaking the tannic acid in ultrasonic oscillation to obtain a tannic acid modified double-layer hydrogel; the dosage of the tannic acid solution is based on immersing the double-layer hydrogel, and the volume of the tannic acid solution in the embodiment is 150 mL; in the tannic acid solution, the mass percentage of tannic acid is 1%.
The tannic acid modified double-layer hydrogel obtained in the embodiment has the pore diameter of 1-30 μm on the upper surface and the pore diameter of 50-300 μm on the lower surface. The tannic acid modified double-layer hydrogel in the embodiment has the advantages that the pore diameter of the upper layer is small, the structure is compact, the pore diameter of the lower layer is large, the structure is loose, the two layers are combined tightly, and the two layers are connected seamlessly.
Example 5
The preparation method of the tannic acid modified double-layer hydrogel of the embodiment comprises the following steps:
dissolving water-soluble chitosan in water to obtain a chitosan aqueous solution, and dissolving polyvinyl alcohol in water at 100 ℃ to obtain a polyvinyl alcohol aqueous solution; the number average molecular weight of the polyvinyl alcohol is 100000; the mass percentage of chitosan in the chitosan aqueous solution is 10%; the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10%;
step two, mixing the chitosan aqueous solution and the polyvinyl alcohol aqueous solution in the step one according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 100 ℃ to obtain a chitosan-polyvinyl alcohol mixed solution;
step three, completely dissolving powdered polyethylene glycol in the chitosan-polyvinyl alcohol mixed solution in the step two until the solution is clear, so as to obtain a hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 1500; in the hydrogel preparation solution, the mass percentage of polyethylene glycol is 6%;
step four, placing the hydrogel preparation liquid obtained in the step three in a room temperature environment for 20min, then pouring the hydrogel preparation liquid into a template, and circularly freezing the template filled with the hydrogel preparation liquid at low temperature to obtain an upper layer of the double-layer hydrogel; the number of times of circulating low-temperature freezing is 2, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 2 times, wherein the temperature of the low-temperature freezing is-10 ℃, the time of the low-temperature freezing is 6 hours, the temperature of the thawing is 20 ℃, and the time of the thawing is 8 hours;
dissolving sodium hyaluronate in water to obtain a sodium hyaluronate aqueous solution, and dissolving polyvinyl alcohol in water at 90 ℃ to obtain a polyvinyl alcohol aqueous solution; the mass percentage of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 0.6%, and the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 24%;
step six, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution in the step five according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 90 ℃ to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution; the number average molecular weight of the polyvinyl alcohol is 100000;
step seven, completely dissolving powdered polyethylene glycol in the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step six until the solution is clear to obtain hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 2000, and the mass percentage of the polyethylene glycol in the hydrogel preparation liquid is 7%;
placing the hydrogel preparation liquid obtained in the step seven in a room temperature environment for 20min, placing the upper layer of the double-layer hydrogel obtained in the step four in a template, pouring the placed hydrogel preparation liquid onto the upper layer of the double-layer hydrogel at room temperature, and adding the hydrogel preparation liquid until the height is 2 times of the thickness of the upper layer of the double-layer hydrogel; then, performing circulating low-temperature freezing to obtain double-layer hydrogel; the number of times of circulating low-temperature freezing is 2, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 2 times, wherein the temperature of the low-temperature freezing is-40 ℃, the time of the low-temperature freezing is 10 hours, the temperature of the thawing is 30 ℃, and the time of the thawing is 10 hours;
step nine, soaking the double-layer hydrogel obtained in the step eight in a tannic acid solution for 48 hours under a dark condition, filtering to obtain a tannic acid soaked double-layer hydrogel, and removing redundant tannic acid on the surface of the double-layer hydrogel after soaking the tannic acid in ultrasonic oscillation to obtain a tannic acid modified double-layer hydrogel; the dosage of the tannic acid solution is based on immersing the double-layer hydrogel, and the volume of the tannic acid solution in the embodiment is 100 mL; in the tannic acid solution, the mass percentage of tannic acid is 8%.
The tannic acid modified double-layer hydrogel obtained in the embodiment has the pore diameter of 1-30 μm on the upper surface and the pore diameter of 50-300 μm on the lower surface. The tannic acid modified double-layer hydrogel in the embodiment has the advantages that the pore diameter of the upper layer is small, the structure is compact, the pore diameter of the lower layer is large, the structure is loose, the two layers are combined tightly, and the two layers are connected seamlessly.
Example 6
The preparation method of the tannic acid modified double-layer hydrogel of the embodiment comprises the following steps:
dissolving water-soluble chitosan in water to obtain a chitosan aqueous solution, and dissolving polyvinyl alcohol in water at 80 ℃ to obtain a polyvinyl alcohol aqueous solution; the number average molecular weight of the polyvinyl alcohol is 120000; the mass percentage of chitosan in the chitosan aqueous solution is 5%; the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 16%;
step two, mixing the chitosan aqueous solution and the polyvinyl alcohol aqueous solution in the step one according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 80 ℃ to obtain a chitosan-polyvinyl alcohol mixed solution;
step three, completely dissolving powdered polyethylene glycol in the chitosan-polyvinyl alcohol mixed solution in the step two until the solution is clear, so as to obtain a hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 4000; in the hydrogel preparation solution, the mass percentage of polyethylene glycol is 7%;
step four, placing the hydrogel preparation liquid obtained in the step three in a room temperature environment for 30min, pouring the hydrogel preparation liquid into a template, and circularly freezing the template filled with the hydrogel preparation liquid at low temperature to obtain an upper layer of the double-layer hydrogel; the number of times of circulating low-temperature freezing is 4, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 4 times, wherein the temperature of the low-temperature freezing is-16 ℃, the time of the low-temperature freezing is 20 hours, the temperature of the thawing is 40 ℃, and the time of the thawing is 6 hours;
dissolving sodium hyaluronate in water to obtain a sodium hyaluronate aqueous solution, and dissolving polyvinyl alcohol in water at 70 ℃ to obtain a polyvinyl alcohol aqueous solution; the mass percentage of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 0.4%, and the mass percentage of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 28%;
step six, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution in the step five according to the volume ratio of 1:1, and preserving the temperature of the mixed solution at 70 ℃ to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution; the number average molecular weight of the polyvinyl alcohol is 120000;
step seven, completely dissolving powdered polyethylene glycol in the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step six until the solution is clear to obtain hydrogel preparation solution; the number average molecular weight of the polyethylene glycol is 3000, and the mass percentage of the polyethylene glycol in the hydrogel preparation liquid is 5%;
placing the hydrogel preparation liquid obtained in the step seven in a room temperature environment for 10min, placing the upper layer of the double-layer hydrogel obtained in the step four in a template, pouring the placed hydrogel preparation liquid onto the upper layer of the double-layer hydrogel at room temperature, and adding the hydrogel preparation liquid until the height is 2 times of the thickness of the upper layer of the double-layer hydrogel; then, performing circulating low-temperature freezing to obtain double-layer hydrogel; the number of times of circulating low-temperature freezing is 2, specifically: placing the template containing the hydrogel preparation solution in a refrigerator for low-temperature freezing, taking out, thawing, and performing the steps of low-temperature freezing-thawing for 2 times, wherein the temperature of the low-temperature freezing is-20 ℃, the time of the low-temperature freezing is 10 hours, the temperature of the thawing is 40 ℃, and the time of the thawing is 6 hours;
step nine, soaking the double-layer hydrogel obtained in the step eight in a tannic acid solution for 1h under a dark condition, filtering to obtain a tannic acid soaked double-layer hydrogel, and removing redundant tannic acid on the surface of the double-layer hydrogel after soaking the tannic acid in ultrasonic oscillation to obtain a tannic acid modified double-layer hydrogel; the dosage of the tannic acid solution is based on immersing the double-layer hydrogel, and the volume of the tannic acid solution in the embodiment is 120 mL; in the tannic acid solution, the mass percentage of tannic acid is 50%.
The tannic acid modified double-layer hydrogel obtained in the embodiment has the pore diameter of 1-30 μm on the upper surface and the pore diameter of 50-300 μm on the lower surface. The tannic acid modified double-layer hydrogel in the embodiment has the advantages that the pore diameter of the upper layer is small, the structure is compact, the pore diameter of the lower layer is large, the structure is loose, the two layers are combined tightly, and the two layers are connected seamlessly.
And (3) performance testing:
taking the bilayer hydrogel prepared in example 1 and the tannic acid modified bilayer hydrogel as examples, as shown in fig. 1 to 6, compared with the bilayer hydrogel without tannic acid modification, the upper surface and the lower surface of the tannic acid modified bilayer hydrogel of the present invention both have a denser pore size structure, and the upper hydrogel and the lower hydrogel are tightly bonded.
The method for evaluating the bacteria-inhibiting performance (fig. 7) includes: placing the gel sample to be detected on a plate agar culture medium, vertically dripping the bacterial suspension from the upper part of the gel sample to be detected, transferring the bacterial suspension into the gel sample to be detected to an incubator for culturing for 24h, stripping agar, ultrasonically separating bacteria, and counting. The evaluation method of the moisture retention performance (figure 8) is a moisture permeable cup method, the test temperature is 50 ℃, and the test time is 24 h. Referring to FIGS. 7 and 8, the tannin-modified bilayer hydrogel (sample 2) of the present invention has better water-holding and bacteria-blocking abilities than the lower layer of the bilayer hydrogel (sample 0) and the bilayer hydrogel (sample 1). The preparation method of the lower layer (sample 0) of the double-layer hydrogel comprises the steps of preparing a hydrogel preparation solution according to the fifth to seventh steps in the example 1, placing the hydrogel preparation solution at room temperature for 30min, pouring the hydrogel preparation solution into a template, and performing circulating low-temperature freezing on the template containing the hydrogel preparation solution to obtain the lower layer of the double-layer hydrogel.
The method for evaluating the bacteriostatic performance is a bacteriostatic circle method, gel samples to be tested are respectively placed on agar culture media which are uniformly coated with bacterial suspensions (escherichia coli and staphylococcus aureus), the bacterial growth condition is observed and photographed for 24 hours (figure 9), and according to the figure 9, compared with the double-layer hydrogel (sample 1), the tannic acid modified double-layer hydrogel (sample 2) disclosed by the invention has stronger growth inhibition capacity on escherichia coli and staphylococcus aureus.
As shown in fig. 10, the tannic acid modified bilayer hydrogel of the present invention can adhere to animal tissue heart, liver, lung, spleen, skin, bone, rubber, glass, steel and plastic surfaces.
The self-healing and performance testing method comprises the following steps: the tannin modified double-layer hydrogel is divided into four parts, the four parts are respectively dyed by dyes with different colors and then spliced, and the healing state is observed after 3 hours. According to fig. 11, the tannic acid modified double-layer hydrogel disclosed by the invention can heal quickly after being damaged, can bear tensile deformation after self-healing and has good self-healing performance. The microscopic characterization of the healing condition of the fracture surface by a scanning electron microscope is shown in fig. 12, the fracture surfaces of the fractured hydrogel are overlapped, and the boundary of the fracture surface is fuzzy, which shows that the tannic acid modified double-layer hydrogel has good self-healing and self-healing capabilities.
The method for testing the scavenging capacity of the free radicals comprises the following steps: and respectively placing the gel sample to be tested in the prepared ABTS solution and DPPH solution for reaction, observing the color change of the solution and testing the absorbance of the solution. According to fig. 13, the absorbance of ABTS reduced by the tannic acid-modified bilayer hydrogel of the present invention (sample 2) was lower at 734nm maximum absorption wavelength than that of ABTS reduced by the bilayer hydrogel (sample 1), and according to fig. 14, the absorbance of DPPH reduced by the tannic acid-modified bilayer hydrogel of the present invention (sample 2) was lower at 519nm maximum absorption wavelength than that of DPPH reduced by the bilayer hydrogel (sample 1), indicating that the tannic acid-modified bilayer hydrogel of the present invention has a higher radical scavenging ability and is capable of effectively resisting oxidation.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. The tannin-modified double-layer hydrogel is characterized in that the aperture of the upper surface of the tannin-modified double-layer hydrogel is 1-30 microns, and the aperture of the lower surface of the tannin-modified double-layer hydrogel is 50-300 microns.
2. The tannin-modified bilayer hydrogel according to claim 1, wherein the tannin-modified bilayer hydrogel has an upper surface pore size of 1 to 10 μm and a lower surface pore size of 70 to 120 μm.
3. A method for preparing the tannin-modified bilayer hydrogel of claim 1 or 2, which comprises soaking the bilayer hydrogel in a tannin solution for 1 to 48 hours under a dark condition, and then ultrasonically oscillating to obtain the tannin-modified bilayer hydrogel.
4. The method as claimed in claim 3, wherein the tannic acid solution comprises 1 to 50% by weight of tannic acid.
5. The method according to claim 3, wherein the soaking time is 3 to 12 hours.
6. The method of claim 3, wherein the bilayer hydrogel is prepared by a method comprising the steps of:
mixing a chitosan aqueous solution and a polyvinyl alcohol aqueous solution to obtain a chitosan-polyvinyl alcohol mixed solution;
step two, dissolving polyethylene glycol into the chitosan-polyvinyl alcohol mixed solution in the step one to obtain a hydrogel preparation solution;
step three, pouring the hydrogel preparation liquid obtained in the step two into a template for circulating low-temperature freezing to obtain an upper layer of the double-layer hydrogel;
step four, mixing the sodium hyaluronate aqueous solution and the polyvinyl alcohol aqueous solution to obtain a sodium hyaluronate-polyvinyl alcohol mixed solution;
step five, dissolving polyethylene glycol into the sodium hyaluronate-polyvinyl alcohol mixed solution obtained in the step four to obtain hydrogel preparation solution;
and step six, pouring the hydrogel preparation liquid obtained in the step five onto the upper layer of the double-layer hydrogel obtained in the step three at room temperature, and performing circulating low-temperature freezing to obtain the double-layer hydrogel.
7. The method according to claim 6, wherein the chitosan content in the chitosan aqueous solution in the first step is 4-20% by weight; step one, the mass percentage of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10-30%; step one, the temperature of the chitosan-polyvinyl alcohol mixed solution is 70-100 ℃; fourthly, the mass percentage content of the sodium hyaluronate in the sodium hyaluronate aqueous solution is 0.1-4%, and the mass percentage content of the polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10-30%; fourthly, the temperature of the sodium hyaluronate-polyvinyl alcohol mixed solution is 70-100 ℃.
8. The method according to claim 6, wherein the number average molecular weight of the polyethylene glycol in the second step is 400 to 4000; in the hydrogel preparation liquid in the second step, the mass percentage of the polyethylene glycol is 5-15%; the number average molecular weight of the polyethylene glycol in the step five is 1500-3000, and in the hydrogel preparation liquid in the step five, the mass percentage of the polyethylene glycol is 5% -10%.
9. The method according to claim 6, wherein the number of times of the cyclic low-temperature freezing in the step three is 2 to 4, each cyclic low-temperature freezing comprises low-temperature freezing and unfreezing, the temperature of the low-temperature freezing is-10 ℃ to-40 ℃, the time of the low-temperature freezing is 2h to 40h, the temperature of the unfreezing is 20 ℃ to 40 ℃, and the time of the unfreezing is 2h to 10 h; and sixthly, the circulation low-temperature freezing is performed for 2-3 times, each circulation low-temperature freezing comprises low-temperature freezing and unfreezing, the low-temperature freezing temperature is-10 ℃ to-40 ℃, the low-temperature freezing time is 2h to 40h, the unfreezing temperature is 20 ℃ to 40 ℃, and the unfreezing time is 2h to 10 h.
10. The method according to claim 6, further comprising placing the hydrogel preparation solution of step two in a room temperature environment for 10min to 30min and placing the hydrogel preparation solution of step five in a room temperature environment for 5min to 20 min.
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