Transparent biomass polyvinyl alcohol hydrogel as well as preparation method and application thereof

Abstract

The invention discloses transparent biomass polyvinyl alcohol hydrogel as well as a preparation method and application thereof. The preparation method comprises the following steps: uniformly mixing biomass polyvinyl alcohol with water to obtain a polyvinyl alcohol aqueous solution, and performing freeze-thaw cycle to obtain the transparent biomass polyvinyl alcohol hydrogel; the number of freezing and thawing cycles is 1-3, the freezing and thawing time for each time is 2-8 hours, and when the PVA used in each milliliter of water is 150 mg, freezing and thawing are performed once, the freezing and thawing time is 2-8 hours, or freezing and thawing are performed three times, and the freezing and thawing time is 2 hours; when the amount of PVA used in each milliliter of water is 100 mg, freezing and thawing are carried out once, and the freezing and thawing time is 2-8 hours, or freezing and thawing are carried out three times, and the freezing and thawing time is 2-4 hours each time; when the PVA used in each milliliter of water is 50mg, freezing and thawing are carried out once, and the freezing and thawing time is 4-8 hours, or freezing and thawing are carried out three times, and the freezing and thawing time is 2-8 hours each time. The hydrogel disclosed by the invention is high in transparency, and the wound healing condition is convenient to observe.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a transparent biomass polyvinyl alcohol (PVA) hydrogel, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogel wound dressings can significantly accelerate the tissue repair process by virtue of their characteristics such as promoting autolytic debridement of wounds, maintaining a moist healing environment, and relieving pain (especially no wound adhesion during dressing change). At the same time, their self-adhesiveness, plasticity, and excellent tissue conformity effectively avoid problems such as easy drying of wounds, mechanical damage, and poor patient comfort caused by traditional dressings.

[0003] Polyvinyl alcohol (hereinafter referred to as PVA) has excellent biocompatibility and biodegradability, and can form a hydrogel without adding additional chemical cross-linking agents (such as glutaraldehyde, etc.), and is one of the most common materials for making wound dressings. However, currently, the large-scale production and application of PVA (hereinafter referred to as fossil PVA) are mainly based on petrochemical processes such as calcium carbide acetylene method, natural gas acetylene method, or petroleum ethylene method. Its production process not only is accompanied by the emission of a large amount of pollutants (such as particulate matter, SO2, CO2, tar residues, etc.), exacerbating environmental health risks, but also faces the problem of rising costs due to non-renewable raw materials. Biomass-derived PVA (hereinafter referred to as biomass PVA) is derived from biomass resources such as sugarcane and potatoes, can realize the secondary utilization of resources, and effectively reduces environmental pollution. In terms of application, when fossil PVA hydrogel is used alone as a wound dressing, it has the defect of insufficient transparency, and often needs to introduce additives such as dimethyl sulfoxide or inorganic salts to regulate its optical properties. For example, the Chinese patent application document with publication number CN112646206 A discloses a highly transparent polyvinyl alcohol hydrogel, a preparation method thereof, and an application thereof. It uses polyvinyl alcohol and inorganic salts as raw materials and water as a solvent. Among them, the concentration of polyvinyl alcohol is 3-30 wt%, and the concentration of inorganic salts is 0.5-29.9 wt%. The prepared polyvinyl alcohol hydrogel has high transparency and can be applied to fields such as medicine, materials, and sensors. However, it needs to add inorganic salts for modification, not only the production method is cumbersome, but more importantly, it will make the composition of the hydrogel complex and may increase the potential toxicity risk. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to prepare a transparent polyvinyl alcohol hydrogel with a simple composition.

[0005] The present invention solves the above technical problems through the following technical means: A preparation method of a transparent biomass polyvinyl alcohol hydrogel, comprising the following steps: S1. Mix biomass polyvinyl alcohol evenly with water to obtain an aqueous polyvinyl alcohol solution; wherein, the mass of polyvinyl alcohol used per milliliter of water is 50 - 150 mg; S2. Perform freeze - thaw cycles on the aqueous polyvinyl alcohol solution obtained in S1 to obtain the transparent biomass polyvinyl alcohol hydrogel; wherein, the number of freeze - thaw cycles is 1 - 3 times, and the freezing and thawing time for each time is 2 - 8 h. And when the mass of polyvinyl alcohol used per milliliter of water is 50 mg, the number of freeze - thaw cycles is 1 time, and the freezing and thawing time is 4 - 8 h, or the number of freeze - thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 8 h; when the mass of polyvinyl alcohol used per milliliter of water is 100 mg, the number of freeze - thaw cycles is 1 time, and the freezing and thawing time is 2 - 8 h, or the number of freeze - thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 4 h; when the mass of polyvinyl alcohol used per milliliter of water is 150 mg, the number of freeze - thaw cycles is 1 time, and the freezing and thawing time is 2 - 8 h, or the number of freeze - thaw cycles is 3 times, and the freezing and thawing time for each time is 2 h.

[0006] Preferably, in S1, the biomass polyvinyl alcohol is produced from one or more biomass resources such as sugarcane and tubers.

[0007] Preferably, in S1, the biomass polyvinyl alcohol is prepared by using one or more of sugarcane and tubers to prepare molasses, then preparing alcohol from molasses, preparing ethylene from alcohol, preparing vinyl acetate from ethylene, preparing polyvinyl acetate from vinyl acetate, and then preparing polyvinyl alcohol from polyvinyl acetate.

[0008] Preferably, in S1, the degree of polymerization of the biomass polyvinyl alcohol is 2600, and the degree of alcoholysis is 99%.

[0009] Preferably, in S1, the biomass polyvinyl alcohol is the biomass polyvinyl alcohol of model 2699 provided by Anhui Wanwei Group Co., Ltd.

[0010] Preferably, the mass of polyvinyl alcohol used per milliliter of water is 50 mg, the number of freeze - thaw cycles is 1 time, and the freezing and thawing time is 4 - 8 h, or the number of freeze - thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 8 h; or, the mass of polyvinyl alcohol used per milliliter of water is 100 mg, the number of freeze - thaw cycles is 1 time, and the freezing and thawing time is 2 - 8 h, or the number of freeze - thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 4 h; or, the mass of polyvinyl alcohol used per milliliter of water is 150 mg, the number of freeze - thaw cycles is 1 time, and the freezing and thawing time is 2 - 8 h, or the number of freeze - thaw cycles is 3 times, and the freezing and thawing time for each time is 2 h.

[0011] Preferably, in S1, the mass of polyvinyl alcohol used per milliliter of water is 50 mg; and / or, the number of freeze-thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 8 h.

[0012] Preferably, the mass of polyvinyl alcohol used per milliliter of water is 50 mg, and it is freeze-thawed 3 times, and the freezing and thawing time for each time is 8 h.

[0013] Preferably, S1 specifically includes the following steps: mixing biomass polyvinyl alcohol with water, stirring at room temperature, then continuously stirring while heating up until the biomass polyvinyl alcohol is completely dissolved, and then standing at room temperature to remove bubbles to obtain the polyvinyl alcohol aqueous solution.

[0014] Preferably, the stirring time at room temperature is 30 min; stir while heating up until the temperature reaches 85 °C, and then continue to stir.

[0015] Preferably, the freezing temperature is -20 °C, and the thawing temperature is room temperature.

[0016] The present invention also provides a transparent biomass polyvinyl alcohol hydrogel, which is prepared by using the preparation method of the transparent biomass polyvinyl alcohol hydrogel.

[0017] Preferably, for the transparent biomass polyvinyl alcohol hydrogel, its transparency is 91.38% - 100%.

[0018] The present invention also provides an application of the transparent biomass polyvinyl alcohol hydrogel as a wound dressing.

[0019] The above dressing is applied to the loading of various types of drugs such as pain relief, anti-inflammatory, and promoting healing, and is used for the treatment of wound surfaces, ulcer surfaces, bacterial infection surfaces, and difficult-to-heal surfaces.

[0020] Preferably, the wound dressing is used to load one or more of ibuprofen, gentamicin sulfate, and sulfamethoxazole.

[0021] Preferably, the transparent biomass polyvinyl alcohol hydrogel loads drugs by physical soaking.

[0022] In comparison, biomass PVA uses renewable resources such as sugarcane and potatoes as raw materials. While realizing the high-value utilization of agricultural by-products, it significantly reduces environmental pollution and shows sustainable development potential. It is found by the present invention that the hydrogel dressing prepared from biomass PVA without adding other chemical reagents has high transparency, can monitor the changes of wounds at any time, and has broad application prospects in the biomedical field.

[0023] The advantages of the present invention are as follows: (1) The present invention provides a highly transparent polyvinyl alcohol hydrogel derived from biomass, which can be used as a wound dressing. The preparation method of this hydrogel is simple and does not require the addition of extra cross-linking agents, which can reduce costs. Compared with traditional PVA hydrogels derived from fossil sources, it has the advantages of high transparency, large adhesion force and large drug loading rate, and is suitable for physical loading and slow release of various drugs such as ibuprofen, gentamicin sulfate and sulfamethoxazole, etc., thus having multiple effects of relieving wound pain, anti-inflammatory, antibacterial and promoting healing.

[0024] (2) The PVA derived from biomass comes from biomass resources such as sugarcane and tubers, which can realize the secondary utilization of resources and effectively reduce environmental pollution.

[0025] (3) The hydrogel of the present invention has water absorption, can promote the absorption of wound fluid and is not easy to adhere. The soft hydrogel increases the comfort of patients. The characteristic of high transparency is convenient for observing the wound healing situation. The adhesion force is appropriate, not easy to fall off and not difficult to remove. The large drug loading rate can improve the utilization efficiency of drugs and reduce the waste of resources.

[0026] (4) The hydrogel of the present invention is formed by the freeze-thaw method and does not require the help of extra chemical reagents for cross-linking. The dressing is loaded with drugs by physical soaking, so that the obtained hydrogel dressing has good biocompatibility and no residue of toxic chemical substances. Description of the Drawings

[0027] Figure 1 It is the comparison of the residual amount of organic impurities in fossil and biomass PVA particles in Example 1 of the present invention; Figure 2 It is the influence of fossil and biomass PVA on the viability of human epidermal keratinocytes in Example 1 of the present invention; Figure 3 It is the comparison of the light transmittance of biomass and fossil PVA hydrogels at a wavelength of 700 nm in Examples 3-10 of the present invention; Figure 4 It is the comparison of the light transmittance of biomass and fossil PVA hydrogels at a wavelength of 700 nm in Examples 11-19 of the present invention; Figure 5 It is the comparison of the light transmittance of biomass and fossil PVA hydrogels at a wavelength of 700 nm in Examples 20-28 of the present invention; Figure 6 It is the comparison effect diagram of the transparency of biomass and fossil PVA hydrogels in Example 7 of the present invention; Figure 7 It is the scanning electron micrograph of the fossil PVA hydrogel in Example 7 of the present invention; Figure 8 It is the scanning electron micrograph of the biomass PVA hydrogel in Example 7 of the present invention; Figure 9 For the effect of the extracts of fossil and biomass PVA hydrogels on the viability of human epidermal keratinocytes in Example 7 of the present invention; Figure 10 For the release amount of inflammatory factor TNF-α after the extracts of fossil and biomass PVA hydrogels act on mouse mononuclear macrophages for 24 hours in Example 7 of the present invention; Figure 11 For the release amount of inflammatory factor IL-6 after the extracts of fossil and biomass PVA hydrogels act on mouse mononuclear macrophages for 24 hours in Example 7 of the present invention; Figure 12 For the release amount of inflammatory factor IL-1β after the extracts of fossil and biomass PVA hydrogels act on mouse mononuclear macrophages for 24 hours in Example 7 of the present invention; Figure 13 For the comparison of the adhesion force between the fossil and biomass PVA hydrogels and pig skin in Example 7 of the present invention; Figure 14 For the physical picture of the adhesion force between the biomass PVA hydrogel and pig skin in Example 7 of the present invention; Figure 15 For the physical picture of the adhesion force between the biomass PVA hydrogel and a centrifuge tube filled with about 45 mL of water in Example 7 of the present invention; Figure 16 For the comparison of the drug loading amount (ibuprofen) of the fossil and biomass PVA hydrogels in Example 34 of the present invention; Figure 17 For the drug (ibuprofen) sustained release effect of the fossil and biomass PVA hydrogels in Example 34 of the present invention; Figure 18 For the comparison of the drug loading amount (gentamicin sulfate) of the fossil and biomass PVA hydrogels in Example 35 of the present invention; Figure 19 For the drug (gentamicin sulfate) sustained release effect of the fossil and biomass PVA hydrogels in Example 35 of the present invention; Figure 20 For the comparison of the drug loading amount (sulfamethoxazole) of the fossil and biomass PVA hydrogels in Example 36 of the present invention; Figure 21 For the drug (sulfamethoxazole) sustained release effect of the fossil and biomass PVA hydrogels in Example 36 of the present invention. Detailed implementation manners

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] The test materials, reagents, etc. used in the following embodiments can be obtained from commercial channels without special instructions.

[0030] For those not specifying specific technologies or conditions in the embodiments, they can all be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications.

[0031] The following PVA from biomass sources and PVA from fossil sources were all provided by Anhui Wanwei Group Co., Ltd. Both types of PVA have the model number 2699, that is, the degree of polymerization is 2600 and the degree of alcoholysis is 99%. Reagents such as ibuprofen, gentamicin sulfate, and sulfamethoxazole were all purchased from Sigma-Aldrich Company in the United States.

[0032] Example 1 Determination of metal and organic impurity residues and biocompatibility evaluation of PVA from fossil and biomass sources (i.e., fossil PVA and biomass PVA) (1) Determination of metal and organic impurity residues in PVA Inductively coupled plasma mass spectrometry was used to quantitatively analyze the residual amounts of metal impurities (aluminum, calcium, chromium, copper, iron, zinc) in fossil PVA and biomass PVA particles. The results are shown in Table 1. Table 1 shows that the metal impurities (aluminum, calcium, chromium, copper, and zinc) in biomass PVA are less than those in fossil PVA. The residual amounts of organic impurities (methanol, acetic acid, methyl acetate, paraldehyde) in the two types of PVA particles were detected using a gas chromatograph. The results are as Figure 1 and Table 2, Figure 1 and Table 2 shows that the residual amounts of organic substances (acetic acid, methyl acetate, and methanol) in biomass PVA are lower than those in fossil PVA.

[0033] Table 1

[0034] Table 2

[0035] (2) Preparation of PVA aqueous solution Take 5 g of biomass PVA, add it to 100 mL of ultrapure water, stir at room temperature for 30 min, then heat up to 85 °C and continue stirring until the PVA particles are completely dissolved. Let it stand at room temperature to expel air bubbles, and prepare a biomass PVA aqueous solution. Use fossil PVA to replace biomass PVA and prepare a fossil PVA aqueous solution in the same way.

[0036] (3)Biocompatibility evaluation of PVA Dilute the fossil and biomass PVA aqueous solutions in the step (2) to 0.5, 1, 1.5, 2, 2.5 mg / mL respectively with DMEM medium containing 10% (v / v) fetal bovine serum, and then add them to cell culture dishes to treat adherent human epidermal keratinocytes. The DMEM medium containing 10% (v / v) fetal bovine serum without PVA is used as a control. After 24 hours, perform CCK8 detection, and the results are as Figure 2 , Figure 2 showing that both types of PVA are non-toxic to human epidermal keratinocytes within the concentration range of 0 - 2.5 mg / mL.

[0037] Example 2 Preparation of fossil and biomass PVA hydrogels Freeze - thaw the biomass and fossil PVA aqueous solutions once in a -20 °C refrigerator, with a freezing time of 2 h. The specific steps are as follows: (1)Preparation of PVA aqueous solution The method is the same as the step (2) in Example 1.

[0038] (2)Preparation of PVA hydrogel Pour the biomass PVA aqueous solution in the step (1) into a mold, freeze it in a -20 °C refrigerator for 2 h, and thaw it at room temperature for 2 h to prepare a PVA hydrogel for standby. Prepare a fossil PVA hydrogel in the same way.

[0039] Examples 3 - 10 The preparation of fossil and biomass PVA hydrogels is only different from that in Example 2 in terms of the number of freeze - thaw cycles and the freezing and thawing time each time. The number of freeze - thaw cycles and the freezing and thawing time each time for each example are shown in Table 3 specifically.

[0040] Table 3

[0041] The gel formation situations of Examples 2 - 10 are shown in Table 4. In Table 4, × indicates that gel cannot be formed, and √ indicates that gel can be formed. It can be seen from Table 4 that a hydrogel cannot be prepared in Example 2, while hydrogels can be prepared in Examples 3 - 10.

[0042] Table 4

[0043] Example 11 Preparation of the fossil and biomass PVA hydrogel, which is only different from Example 2 in that: the amount of PVA is changed to 10 g to prepare the PVA aqueous solution.

[0044] Examples 12 - 19 Preparation of the fossil and biomass PVA hydrogel, which is only different from Example 11 in that: different freeze - thaw cycles and the time of each freezing and thawing are adopted. The specific freeze - thaw cycles and the time of each freezing and thawing of each example are shown in Table 5 below; Table 5

[0045] The gel - forming situations of Examples 11 - 19 are shown in Table 6, where × represents that gel cannot be formed and √ represents that gel can be formed; it can be seen from Table 6 that hydrogels can be prepared in Examples 11 - 19.

[0046] Table 6

[0047] Example 20 Preparation of the fossil and biomass PVA hydrogel, which is only different from Example 2 in that: the amount of PVA is changed to 15 g to prepare the PVA aqueous solution.

[0048] Examples 21 - 28 Preparation of the fossil and biomass PVA hydrogel, which is only different from Example 20 in that: the number of freeze - thaw cycles and the time of each freezing and thawing. The specific freeze - thaw cycles and the time of each freezing and thawing of each example are shown in Table 7 below; Table 7

[0049] The gel - forming situations of Examples 20 - 28 are shown in Table 8, where × represents that gel cannot be formed and √ represents that gel can be formed; it can be seen from Table 8 that hydrogels can be prepared in Examples 20 - 28.

[0050] Table 8

[0051] Example 29 Transparency detection of the PVA hydrogel Respectively cut the fossil and biomass PVA hydrogels in Examples 3 - 28 into rectangles with a thickness of 1 mm, and use an ultraviolet - visible spectrophotometer to measure the absorbance of all hydrogels at a wavelength of 700 nm, so as to calculate the transmittance of the hydrogels. The results are as Figures 3 - 5 shown.

[0052] Figure 3 It is a comparison of the light transmittance of fossil and biomass PVA hydrogels in Examples 3 - 10. Among them, 2h, 4h, and 8h represent the freezing / thawing time in each example. From left to right, every two bar graphs form a group, with a total of 8 groups, successively representing Examples 3 - 10; Figure 3 It shows that among the hydrogels prepared under the same freezing - thawing conditions, the light transmittance of the biomass PVA hydrogel is higher than that of the fossil PVA hydrogel.

[0053] Figure 4 It is a comparison of the light transmittance of fossil PVA and biomass PVA hydrogels in Examples 11 - 19. Among them, 2h, 4h, and 8h represent the freezing / thawing time in each example. From left to right, every two bar graphs form a group, with a total of 9 groups, successively representing Examples 11 - 19; Figure 4 It shows that among the hydrogels prepared under the same freezing - thawing conditions, the light transmittance of the biomass PVA hydrogel is higher than that of the fossil PVA hydrogel.

[0054] Figure 5 It is a comparison of the light transmittance of fossil and biomass PVA hydrogels in Examples 20 - 28. Among them, 2h, 4h, and 8h represent the freezing / thawing time in each example. From left to right, every two bar graphs form a group, with a total of 9 groups, successively representing Examples 20 - 28; Figure 5 It shows that among the hydrogels prepared under the same freezing - thawing conditions, the light transmittance of the biomass PVA hydrogel is higher than that of the fossil PVA hydrogel.

[0055] Figure 6 It is a physical picture of the fossil and biomass PVA hydrogels prepared in Example 7 (the PVA aqueous solution was frozen at - 20°C for 8 hours and thawed at room temperature for 8 hours, and freeze - thawed 3 times).

[0056] From Figures 3 - 6 it can be seen that compared with the fossil PVA hydrogel, the biomass PVA hydrogel has a higher light transmittance. The light transmittance of the biomass PVA hydrogels prepared in Examples 3 - 7, Examples 11 - 15, and Examples 20 - 23 reaches 91.38 - 100%, while the light transmittance of the fossil PVA hydrogel and the biomass PVA hydrogels prepared in other examples is lower than 90%.

[0057] Example 30 Microstructural characterization of fossil and biomass PVA hydrogels After freeze - drying the fossil and biomass PVA hydrogels in Example 7, a scanning electron microscope was used to take pictures, and the results are as shown in Figure 7 and Figure 8 , Figure 7 It is a scanning electron micrograph of the fossil PVA hydrogel in Example 7, indicating that there is no obvious pore structure on the surface of the fossil PVA hydrogel, Figure 8It is the scanning electron micrograph of the biomass PVA hydrogel in Example 7, indicating that the biomass PVA hydrogel has a porous network structure, which is beneficial for drug loading and slow release.

[0058] Example 31 Biocompatibility evaluation of PVA hydrogel The extracts of fossil and biomass PVA hydrogels (prepared by the method in Example 7) (refer to ISO10993-12; GB / T16886.12-2017, that is, the extraction ratio of the hydrogel to DMEM medium containing 10% (v / v) fetal bovine serum is 1.25 cm 2 / mL, extracted at 37 °C for 24 h) were used to treat adherent human epidermal keratinocytes respectively. The DMEM medium containing 10% (v / v) fetal bovine serum without hydrogel was used as a control. After 24 hours, CCK8 assay was performed. The results are as Figure 9 , Figure 9 shown, indicating that fossil and biomass PVA hydrogels have no effect on the viability of human epidermal keratinocytes, meaning that both PVA hydrogels are non-toxic to cells.

[0059] Example 32 Immunotoxicity evaluation of PVA hydrogel The extracts of fossil and biomass PVA hydrogels (prepared by the method in Example 7) (refer to ISO10993-12; GB / T16886.12-2017, that is, the extraction ratio of the hydrogel to DMEM medium containing 10% (v / v) fetal bovine serum is 1.25 cm 2 / mL, extracted at 37 °C for 24 h) were used to treat adherent mouse mononuclear macrophages respectively. The DMEM medium containing 10% (v / v) fetal bovine serum without hydrogel was used as a control. After 24 hours, an ELISA kit was used to detect the release amounts of inflammatory factors (TNF-α, IL-6 and IL-1β). The results are as Figures 10 - 12 shown, indicating that fossil and biomass PVA hydrogels do not cause inflammatory responses in cells.

[0060] Example 33 Detection of the adhesion force between PVA hydrogel and pig skin Prepare rectangular fossil and biomass PVA hydrogel samples (prepared by the method of Example 7), and fix them on glass slides. At the same time, prepare a rectangular piece of pigskin, fix it on another glass slide with glue, bond the adhesive surface of the hydrogel to the surface of the pigskin, and press it with a weight of 100 g for 5 minutes to ensure good bonding effect. Place the fixed samples in the upper and lower fixtures of a universal material testing machine, set a stable stretching speed of 5 mm / min, start the testing machine for stretching until the hydrogel sample separates from the surface of the pigskin. The results are as Figure 13 shown, indicating that the adhesion between the biomass PVA hydrogel and the pigskin is greater than that of the fossil PVA hydrogel. Figure 14 Figure Figure 14 is a physical picture of the adhesion between the biomass PVA hydrogel and the pigskin. Figure 15 Figure Figure 15 is a physical picture of the adhesion between the biomass PVA hydrogel and an EP tube containing about 45 mL of water, indicating that the biomass PVA hydrogel has sufficient adhesion and the hydrogel dressing prepared from it is not easy to fall off when adhered to the wound area.

[0061] Example 34 Drug loading (ibuprofen) and drug release experiment of PVA hydrogel (1) Loading drugs (ibuprofen) into PVA hydrogel Take a certain amount of ibuprofen powder, and prepare it into a 2 mg / mL drug ibuprofen suspension with ultrapure water. Place the fossil and biomass PVA hydrogels (prepared by the method in Example 7) in two centrifuge tubes containing 10 mL of the above ibuprofen suspension respectively and soak for 72 h for physical drug loading.

[0062] (2) Detection of drug loading amount of PVA hydrogel 1) Establish a standard curve of ibuprofen Prepare a series of suspensions with different concentrations of ibuprofen, and use an ultraviolet-visible spectrophotometer to measure the absorbance A of the drug. Plot the absorbance A against the drug concentration C to obtain the standard curve of the drug.

[0063] 2) Detection of drug loading amount of PVA hydrogel Take out the hydrogel loaded with drugs in step (1), use an ultraviolet-visible spectrophotometer to detect the drug concentration of the remaining drug suspension, and measure the volume of the remaining drug suspension. Calculate the drug loading amount of the hydrogel using the following formula:

[0064] where L is the drug loading amount of the hydrogel (mg / g); C0 and C1 are the concentrations of the drug suspension before and after drug loading (mg / mL) respectively; V0 and V1 are the volumes of the drug solution before and after drug loading (mL) respectively; M is the mass of the hydrogel before drug loading (g). The results are as Figure 16As shown, it indicates that the biomass PVA hydrogel has a high drug loading capacity, and the drug loading amount is significantly higher than that of the fossil PVA hydrogel.

[0065] (3)In vitro drug release experiment Put the hydrogel loaded with ibuprofen in (1) into a centrifuge tube containing 50 mL of 1× phosphate buffered saline (1×PBS) for the drug release experiment. The centrifuge tube is placed in a shaker, with the temperature set at 37 °C and the rotation speed at 100 rpm. Using the cumulative release method, samples are taken at set time intervals and fresh PBS is added. The absorbance of the drug is measured with a UV-visible spectrophotometer, and then the concentration of the drug is calculated according to the standard curve, thereby obtaining the cumulative drug release amount at each time point. Until the absorbance of the drug in the release solution cannot be detected, this is the release end point. The experimental results are as Figure 17 shown, indicating that both PVAs have a certain drug sustained-release effect on ibuprofen and can continuously release the drug for up to 6 hours.

[0066] Example 35 Drug loading (gentamicin sulfate) and drug release experiment of PVA hydrogel Dilute the gentamicin sulfate solution to 3 mg / mL with ultrapure water. Place the fossil and biomass PVA hydrogels (prepared by the method in Example 7) in two centrifuge tubes containing 10 mL of the above gentamicin sulfate solution and soak for 72 h for physical loading of the drug.

[0067] (2)Drug loading amount detection The method is the same as step (2) in Example 34. The results are as Figure 18 , indicating that the biomass PVA hydrogel has a high drug loading capacity.

[0068] (3)In vitro drug release experiment The method is the same as step (3) in Example 34. The results are as Figure 19 , indicating that both PVA hydrogels have a certain sustained-release effect on gentamicin sulfate.

[0069] Example 36 (1)Drug loading (sulfamethoxazole) and drug release experiment of PVA hydrogel Disperse sulfamethoxazole in ultrapure water to prepare a suspension of 3 mg / mL. Place the fossil and biomass PVA hydrogels (prepared by the method in Example 7) in two centrifuge tubes containing 10 mL of the above drug suspension and soak for 72 h for physical loading of the drug.

[0070] (2)Drug loading amount detection The method is the same as step (2) in Example 34. The results are as Figure 20, indicating that the drug loading capacity of the biomass PVA hydrogel is larger than that of the fossil PVA hydrogel.

[0071] (3) In vitro drug release experiment The method is the same as the step (3) in Example 34. The results are as Figure 21 , indicating that both PVA hydrogels have a certain sustained release effect on sulfamethoxazole.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a transparent biomass polyvinyl alcohol hydrogel, characterized in that: It includes the following steps: S1. Mix biomass polyvinyl alcohol uniformly with water to obtain a polyvinyl alcohol aqueous solution; wherein, the mass of polyvinyl alcohol used per milliliter of water is 50 - 150 mg; S2. Subject the polyvinyl alcohol aqueous solution obtained in S1 to freeze-thaw cycles to obtain the transparent biomass polyvinyl alcohol hydrogel; wherein, the number of freeze-thaw cycles is 1 - 3 times, and the freezing and thawing time for each time is 2 - 8 h. Moreover, when the mass of polyvinyl alcohol used per milliliter of water is 50 mg, the number of freeze-thaw cycles is 1 time, and the freezing and thawing time are both 4 - 8 h, or the number of freeze-thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 8 h; when the mass of polyvinyl alcohol used per milliliter of water is 100 mg, the number of freeze-thaw cycles is 1 time, and the freezing and thawing time are both 2 - 8 h, or the number of freeze-thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 4 h; when the mass of polyvinyl alcohol used per milliliter of water is 150 mg, the number of freeze-thaw cycles is 1 time, and the freezing and thawing time are both 2 - 8 h, or the number of freeze-thaw cycles is 3 times, and the freezing and thawing time for each time is 2 h.

2. The preparation method of the transparent biomass polyvinyl alcohol hydrogel according to claim 1, characterized in that: In S1, the biomass polyvinyl alcohol is prepared by using one or more of sugarcane and tubers to prepare molasses, then preparing alcohol from molasses, preparing ethylene from alcohol, preparing vinyl acetate from ethylene, preparing polyvinyl acetate from vinyl acetate, and then preparing it from polyvinyl acetate.

3. The preparation method of the transparent biomass polyvinyl alcohol hydrogel according to claim 1, characterized in that: In S1, the degree of polymerization of the biomass polyvinyl alcohol is 2600, and the degree of alcoholysis is 99%.

4. The preparation method of the transparent biomass polyvinyl alcohol hydrogel according to claim 1, wherein: In S1, the biomass polyvinyl alcohol is the biomass polyvinyl alcohol of model 2699 provided by Anhui Wanwei Group Co., Ltd.

5. The preparation method of the transparent biomass polyvinyl alcohol hydrogel according to claim 1, characterized in that: In S1, the mass of polyvinyl alcohol used per milliliter of water is 50 mg; and / or, the number of freeze-thaw cycles is 3 times, and the freezing and thawing time for each time is 2 - 8 h.

6. The preparation method of the transparent biomass polyvinyl alcohol hydrogel according to claim 1, characterized in that: S1 specifically includes the following steps: Mix biomass polyvinyl alcohol with water, stir at room temperature, then continue to stir while heating until the biomass polyvinyl alcohol is completely dissolved, and then let it stand at room temperature to eliminate bubbles to obtain the polyvinyl alcohol aqueous solution.

7. The preparation method of the transparent biomass polyvinyl alcohol hydrogel according to any one of claims 1-6, characterized in that: The temperature for freezing is -20 °C, and the temperature for thawing is room temperature.

8. A transparent biomass polyvinyl alcohol hydrogel, characterized in that: It is prepared by using the preparation method of the transparent biomass polyvinyl alcohol hydrogel as described in any one of claims 1 - 7.

9. The transparent biomass polyvinyl alcohol hydrogel according to claim 8, characterized in that: Its light transmittance is 91.38 - 100%.

10. Application of a transparent biomass polyvinyl alcohol hydrogel as described in claim 8 or 9 as a wound dressing.

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