Hydrogel adhesive based on gelatin and clay material and preparation method thereof

Abstract

The invention discloses a hydrogel adhesive based on gelatin and a clay material and a preparation method of the hydrogel adhesive. The hydrogel adhesive at least comprises the following preparation raw materials: modified gelatin, a modified clay material and a thiolated cross-linking agent. The hydrogel adhesive prepared by the invention has an excellent tissue adhesion effect in a moist environment, can form gel within 30-60s, has flexibly adjustable adhesion performance, and can meet the application of various surgical scenes. The fibrin glue has the blood coagulation promoting effect, the hemostasis effect is better than that of traditional fibrin glue, the antibacterial effect is achieved, the risk of wound infection is reduced, meanwhile, good elasticity and toughness are achieved, the matching degree with tissue mechanical properties is high, and the fibrin glue cannot lose efficacy during cyclic compression. The biological compatibility is good, the anti-inflammatory and anti-oxidation effects are achieved, and wound healing and regeneration can be accelerated.

Description

Technical Field

[0001] The present invention relates to materials for surgical supplies, and specifically to a hydrogel adhesive based on gelatin and clay materials and a preparation method thereof. Background Art

[0002] Surgical adhesives can be used to close wounds and promote tissue healing during surgical operations. Currently, common surgical adhesives are mostly cyanoacrylate adhesives and fibrin adhesives. Their adhesiveness and mechanical properties are insufficient in a humid environment, and it takes a long time to form glue, which prolongs the surgical time and is prone to cause the reproduction of bacteria and complications. Moreover, the elasticity of cyanoacrylate adhesives is insufficient, and they will fail and fall off under stress and cyclic compression after adhering to the skin. Therefore, it is crucial to develop an adhesive with excellent adhesiveness in a humid environment and good matching performance with the skin and tissues.

[0003] Chinese invention patent CN116531551B discloses a fibrinogen-based patch and its preparation method and application. The preparation raw materials include fibrinogen and a stabilizer. Some lysine residues of the fibrinogen contain hydrophobic groups, which have good biocompatibility and can be absorbed by the human body, but it takes several minutes to form glue, prolonging the surgical time. Chinese invention patent application CN1154129A discloses a pH-regulated biocompatible monomer and polymer composition. A small amount of moisture present on the surface of the adhesive catalyzes the polymerization of the monomer, and the formed adhesive has the flexibility and strength required to withstand the normal movement of tissues. However, the raw material formaldehyde used in its preparation has a concentration change process during use and has potential toxicity. Summary of the Invention

[0004] In order to develop an adhesive with excellent adhesiveness in a humid environment and good matching performance with the skin and tissues, the first aspect of the present invention provides a hydrogel adhesive based on gelatin and clay materials, and the preparation raw materials at least include modified gelatin, modified clay materials and a thiolated crosslinking agent.

[0005] As an implementation manner, the modified clay material is a polyphenol-modified clay material, and the clay material includes but is not limited to at least one of montmorillonite, attapulgite, laponite or lithium magnesium silicate.

[0006] As an implementation manner, the number of phenolic hydroxyl groups in the polyphenol-modified clay material ≥ 2.

[0007] As an implementation manner, the modification materials of the polyphenol-modified clay material include but are not limited to at least one of hydrochloric acid dopamine (Dopa), dopamine quinone, gallic acid, epigallocatechin gallate, quercetin, 2,3-dihydroxybenzoic acid or tannic acid.

[0008] As an implementation manner, the modified clay material is polydopamine-modified montmorillonite.

[0009] As an implementation manner, the preparation method of the polydopamine-modified montmorillonite (PDA-clay) comprises the following steps:

[0010] Add Dopa into Tris buffer solution to obtain a Dopa solution;

[0011] Add montmorillonite (Clay) into the Dopa solution to form a montmorillonite suspension;

[0012] Stir at 500 - 1000 rpm for 10 - 15 h at room temperature, and then freeze-dry to obtain polydopamine-modified montmorillonite.

[0013] As an implementation manner, the mass concentration of Dopa in the Dopa solution is 3 - 5%, and the mass concentration of Dopa in the Dopa solution is 3.75%.

[0014] As an implementation manner, the concentration of the Tris buffer solution is 5 - 15 mM, and the pH is 8 - 9.

[0015] As an implementation manner, the concentration of the Tris buffer solution is 10 mM, and the pH is 8.5.

[0016] As an implementation manner, the mass concentration of the montmorillonite suspension is 1 - 5%, the mass concentration of the montmorillonite suspension is 1 - 3%, and the mass concentration of the montmorillonite suspension is 2%.

[0017] As an implementation manner, the preparation raw materials further include an initiator, the thiolated cross-linking agent is thiolated gelatin, and the thiolated cross-linking agent accounts for 0 - 15% of the weight of the hydrogel adhesive, excluding 0%.

[0018] The inventor found during the experiment that using clay materials to modify gelatin can obtain an adhesive that can have excellent bonding effects in a humid environment. The reason may be that the polyphenol-functionalized clay used for modification can promote the rapid gelation of the modified gelatin material, and the strong proteins in the functionalized clay have an adsorption effect, which can cause blood to coagulate quickly and has a blood coagulation function, so that the adhesive can provide excellent adhesion effects in a humid environment and surgical scenarios.

[0019] The inventor further found that the gelatin material modified with clay has a certain antibacterial effect. The reason is that the modified gelatin material can aggregate and adhere to bacteria, destroy the biofilm of bacteria, reduce the infection risk of the wound surface, and the gelatin adhesive has a certain flexibility, better adhesion to the skin, and will not fall off and fail after rotational compression, so it has a wide range of application scenarios.

[0020] As an implementation manner, the initiator is a biocompatible initiator, including but not limited to at least one of lithium phenyl-2,4,6-trimethylbenzoylphosphine (LAP), Irgacure 2959, eosin Y, horseradish peroxidase, and hydrogen peroxide.

[0021] As an implementation manner, the thiolated crosslinking agent accounts for 1-5% of the weight of the hydrogel adhesive.

[0022] As an implementation manner, the thiolated crosslinking agent accounts for 1.75% of the weight of the hydrogel adhesive.

[0023] As an implementation manner, the modified gelatin is acrylic acid modified gelatin, and the acrylic acid modified gelatin includes at least one of methacryloylated gelatin, norbornene modified gelatin, or glycidyl methacrylate modified gelatin.

[0024] As an implementation manner, the acrylic acid modified gelatin accounts for 3-30% of the weight of the hydrogel adhesive.

[0025] As an implementation manner, the acrylic acid modified gelatin accounts for 5-15% of the weight of the hydrogel adhesive.

[0026] As an implementation manner, the acrylic acid modified gelatin accounts for 5% of the weight of the hydrogel adhesive.

[0027] As an implementation manner, the weight ratio of the acrylic acid modified gelatin to the modified clay material is (3-30):(0-10), excluding 0.

[0028] As an implementation manner, the weight ratio of the acrylic acid modified gelatin to the modified clay material is (5-15):(1-5).

[0029] As an implementation manner, the weight ratio of the acrylic acid modified gelatin to the modified clay material is 5:(1-2).

[0030] As an implementation manner, the weight ratio of the acrylic acid modified gelatin to the modified clay material is 5:1, 5:1.5, or 5:2.

[0031] As an implementation manner, the preparation method of the methacryloylated gelatin (GelMA) includes the following steps:

[0032] Add gelatin to buffer solution I to obtain a gelatin solution;

[0033] Add methacrylic anhydride to the gelatin solution and mix well to obtain a mixture;

[0034] The mixed solution reacts under stirring at 200 - 400 rpm for 2 - 5 h in an environment of 30 - 50 °C;

[0035] After the reaction is completed, buffer solution I is added to terminate the reaction, followed by dialysis for 48 - 72 h, freezing, and lyophilization to obtain methacrylated gelatin.

[0036] As an implementation manner, the volume - mass ratio of methacrylic anhydride to gelatin is (0.5 - 1.5) mL:1 g.

[0037] As an implementation manner, the volume - mass ratio of methacrylic anhydride to gelatin is 1 mL:1 g.

[0038] As an implementation manner, buffer solution I is phosphate - buffered saline (PBS).

[0039] As an implementation manner, the concentration of the phosphate - buffered saline is 0.01 - 0.03 mol / L, and the pH is 7.25 - 7.35.

[0040] As an implementation manner, the concentration of the phosphate - buffered saline is 0.01 mol / L, and the pH is 7.25 - 7.35.

[0041] As an implementation manner, the dialysis is carried out using a dialysis bag, and the cut - off molecular weight of the dialysis bag is 3000 - 4000 Da.

[0042] As an implementation manner, the dialysis is carried out using a dialysis bag, and the cut - off molecular weight of the dialysis bag is 3500 Da.

[0043] As an implementation manner, the preparation method of norbornene - modified gelatin (GelNB) includes the following steps:

[0044] Add 5 - norbornene - 2 - carboxylic acid to buffer solution II to obtain a 5 - norbornene - 2 - carboxylic acid solution;

[0045] Add an activator to the 5 - norbornene - 2 - carboxylic acid solution and stir at 40 - 60 °C for 10 - 20 min for activation;

[0046] Add gelatin to the activated 5 - norbornene - 2 - carboxylic acid solution and adjust the pH to 7.5 - 7.8 to obtain a mixed reactant;

[0047] Stir the mixed reactant at 40 - 60 °C for 10 - 15 h and centrifuge at 1500 - 2500 rpm for 1 - 5 min;

[0048] After centrifugation, the supernatant is dialyzed for 48 - 72 h, frozen, and lyophilized to obtain norbornene - modified gelatin.

[0049] As an implementation manner, the buffer solution II is MES buffer solution, the concentration of the MES buffer solution is 0.5M, and the pH is 6.

[0050] As an implementation manner, the activator is a combination of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC·HCl) and N-hydroxysuccinimide (NHS);

[0051] As an implementation manner, the weight ratio of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride to N-hydroxysuccinimide is (1-1.2):(0.3-0.5).

[0052] As an implementation manner, the weight ratio of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride to N-hydroxysuccinimide is 1.02:0.31.

[0053] As an implementation manner, the weight ratio of 5-norbornene-2-carboxylic acid to gelatin is (0.35-0.4):1.

[0054] As an implementation manner, the weight ratio of 5-norbornene-2-carboxylic acid to gelatin is 368:1.

[0055] As an implementation manner, the preparation method of the thiolated gelatin (GelSH) includes the following steps:

[0056] Add gelatin into deionized water to prepare a gelatin solution, and purge with inert gas;

[0057] Add the chelating agent into deionized water to prepare a chelating agent solution;

[0058] Add the chelating agent solution and the modifier into the gelatin solution purged with inert gas, stir at 500-800 rpm, and react in an ice bath in the dark for 3-5 h;

[0059] After the reaction, dialyze in the dark for 48-72 h, freeze, and lyophilize to obtain thiolated gelatin.

[0060] As an implementation manner, the chelating agent is imidazole.

[0061] The modifier includes but is not limited to at least one of DL-N-acetylhomocysteine thiolactone, 4-butyl mercaptolactone, or N-acetyl-L-cysteine.

[0062] As an implementation manner, the weight-to-volume ratio of gelatin, imidazole, and the modifier is 1 g:(0.6-1) g:(0.5-1) mL.

[0063] As an implementation manner, the weight-to-volume ratio of gelatin, imidazole, and the modifier is 1 g:0.68 g:0.85 mL.

[0064] As an implementation method, the dialysis is carried out with a cysteine solution, and the concentration of the cysteine solution is 0.5-1 wt%; the concentration of the cysteine solution is 0.7 wt%.

[0065] The second aspect of the present invention provides a preparation method of a hydrogel adhesive based on gelatin and clay materials, comprising the following steps:

[0066] S1 Prepare a modified gelatin solution and mix it with a modified clay material;

[0067] S2 Add a thiolated crosslinking agent and stir at 30-50 °C for 10-20 min;

[0068] S3 Add an initiator, mix for 10-20 min; carry out photocuring crosslinking to obtain a hydrogel adhesive.

[0069] As an implementation method, the preparation method of the modified gelatin solution comprises the following steps: add methacrylated gelatin to PBS at 60 °C, and the concentration of methacrylated gelatin is 3-5 wt%.

[0070] As an implementation method, the preparation method of the modified gelatin solution comprises the following steps: add methacrylated gelatin to PBS at 60 °C, and the concentration of methacrylated gelatin is 5 wt%.

[0071] As an implementation method, the light for photocuring crosslinking is ultraviolet light or visible light, the wavelength of the light is 320-550 nm, and the curing time is 10-120 s.

[0072] As an implementation method, the energy of the light for photocuring crosslinking is 100 mW / cm 2 .

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] (1) For the hydrogel adhesive based on gelatin and clay materials of the present invention, by introducing polyphenol-modified clay materials, the prepared hydrogel adhesive has excellent tissue adhesion effect in a humid environment, and can form a gel within 30-60 s. The adhesion performance of the adhesive can be flexibly adjusted to meet the application requirements of various surgical scenarios.

[0075] (2) For the hydrogel adhesive based on gelatin and clay materials of the present invention, using polyphenol-modified materials to modify montmorillonite can coagulate blood within 100 s, has the effect of promoting blood coagulation, the hemostatic effect is better than that of traditional fibrin glue, and also has the effect of antibacterial, reducing the risk of wound infection.

[0076] (3) The hydrogel adhesive based on gelatin and clay materials in the present invention adopts a combination of acrylic acid-modified gelatin and modified clay materials, has good biocompatibility, has the effects of anti-inflammatory and antioxidant, and can accelerate wound healing and regeneration.

[0077] (4) For the hydrogel adhesive based on gelatin and clay materials in the present invention, the acrylic acid-modified gelatin and the modified clay materials are in a weight ratio of (5-15):(1-5), so that the hydrogel adhesive has good elasticity and toughness, a high degree of matching with tissue mechanical properties, and will not fail during cyclic compression.

[0078] (5) The hydrogel adhesive based on gelatin and clay materials in the present invention has low raw material prices, a simple preparation process, and uses natural raw materials, has high safety, good biocompatibility, and is biodegradable. Moreover, based on different scenarios such as nerve, ophthalmic, and vascular surgeries, the mechanical and adhesion properties can be flexibly adjusted. Description of the Drawings

[0079] Figure 1 Comparative NMR pictures of methacrylated gelatin and gelatin prepared in Example 1, top: methacrylated gelatin, bottom: unmodified gelatin.

[0080] Figure 2 Comparative NMR pictures of norbornene-modified gelatin and gelatin prepared in Example 2, top: norbornene-modified gelatin, bottom: unmodified gelatin.

[0081] Figure 3 Infrared spectra of methacrylated gelatin prepared in Example 1, norbornene-modified gelatin prepared in Example 2, and thiolated gelatin prepared in Example 1. From left to right: methacrylated gelatin, norbornene-modified gelatin, and thiolated gelatin.

[0082] Figure 4 Pictures of the actual preparation process of polydopamine-modified montmorillonite in Example 1.

[0083] Figure 5 Infrared spectrum of polydopamine-modified montmorillonite prepared in Example 1.

[0084] Figure 6 Ultraviolet spectrum of polydopamine-modified montmorillonite prepared in Example 1.

[0085] Figure 7 Schematic diagram of the structure of the hydrogel adhesive prepared in Example 1.

[0086] Figure 8 Pictures of the physical objects of the hydrogel adhesives prepared in Example 1 and Comparative Examples 1-2, upper layer: front view, lower layer: top view. From left to right: Comparative Example 2, Comparative Example 1, Example 1.

[0087] Figure 9 For Example 2, physical pictures of the hydrogel adhesives prepared in Comparative Examples 3-4, upper layer: front view, lower layer: top view. From left to right: Comparative Example 4, Comparative Example 3, Example 2.

[0088] Figure 10 Adhesion test photos of the hydrogel adhesive prepared in Example 1 attached to pig skin.

[0089] Figure 11 Adhesion test photos of the hydrogel adhesive prepared in Example 1 attached to a finger.

[0090] Figure 12 Torsion test photos of the hydrogel adhesive prepared in Example 1 attached to pig skin.

[0091] Figure 13 Point force-strain curves of the hydrogel adhesives prepared in Example 1 and Comparative Examples 1-2 attached to pig skin. In the figure: 1. Methacrylated gelatin; 2. Comparative Example 2; 3. Comparative Example 1; 4. Example 1.

[0092] Figure 14 Hemolysis experiment photos of the hydrogel adhesives prepared in Examples 1-2 and Comparative Examples 1-4. From left to right: Comparative Example 4, Comparative Example 3, Example 2, Comparative Example 2, Comparative Example 1, Example 1, positive control, negative control.

[0093] Figure 15 Coagulation experiment photos of the hydrogel adhesives prepared in Examples 1-2 and Comparative Examples 1-4. From left to right: Comparative Example 4, Comparative Example 3, Example 2, Comparative Example 2, Comparative Example 1, Example 1, blank control.

[0094] Figure 16 Bar chart of the hemolysis rates of the hemolysis experiment tests of the hydrogel adhesives prepared in Examples 1-2 and Comparative Examples 1-4.

[0095] Figure 17 Bar chart of the coagulation indices of the coagulation experiment tests of the hydrogel adhesives prepared in Examples 1-2 and Comparative Examples 1-4.

[0096] Figure 18 Upright photos of the hydrogel adhesives prepared in Comparative Examples 5-7. From left to right: Comparative Example 5, Comparative Example 6, Comparative Example 7.

[0097] Figure 19 Inverted photos of the hydrogel adhesives prepared in Comparative Examples 5-7. From left to right: Comparative Example 5, Comparative Example 6, Comparative Example 7. Detailed implementation methods

[0098] Note: The gelatin used in the examples and comparative examples is specifically porcine gelatin, with a gel strength of ~100 g Bloom, and the supplier is Shanghai Aladdin Biochemical Technology Co., Ltd.

[0099] Example 1

[0100] A hydrogel adhesive based on gelatin and clay materials, the preparation raw materials at least include modified gelatin, modified clay materials, thiolated cross-linking agent and initiator.

[0101] The modified clay material is polydopamine-modified montmorillonite, and the preparation method includes the following steps:

[0102] Add Dopa to Tris buffer to obtain a Dopa solution;

[0103] Add montmorillonite to the Dopa solution to form a montmorillonite suspension;

[0104] Stir at 800 rpm for 12 h at 25 °C, and freeze-dry to obtain polydopamine-modified montmorillonite.

[0105] The mass concentration of Dopa in the Dopa solution is 3.75%.

[0106] The concentration of the Tris buffer is 10 mM, and the pH is 8.5.

[0107] The mass concentration of the montmorillonite suspension is 2%.

[0108] The modified gelatin is methacrylated gelatin, and the preparation method includes the following steps:

[0109] Add 10 g of gelatin to 100 mL of buffer solution I to obtain a gelatin solution;

[0110] Add 10 mL of methacrylic anhydride to the gelatin solution and mix well to obtain a mixed solution;

[0111] The mixed solution is stirred at 300 rpm for 3 h at 40 °C for reaction;

[0112] After the reaction is completed, add 200 mL of buffer solution I to terminate the reaction, dialyze for 72 h, freeze at -80 °C overnight and then lyophilize for 72 h to obtain methacrylated gelatin.

[0113] The buffer solution I is a phosphate buffer solution, and the concentration of the phosphate buffer solution is 0.01 mol / L, and the pH is 7.25 - 7.35.

[0114] The dialysis is dialysis bag dialysis, and the cut-off molecular weight of the dialysis bag is 3500 Da.

[0115] The thiolated cross-linking agent is thiolated gelatin, and the preparation method includes the following steps:

[0116] 1 g of gelatin was added to 50 mL of deionized water at 40 °C to prepare a gelatin solution, which was purged with N2 for 20 min;

[0117] 0.68 g of chelating agent was added to 5 mL of deionized water to prepare a chelating agent solution;

[0118] The chelating agent solution and 0.85 mL of modifier were added to the gelatin solution after purging with inert gas, and stirred at 600 rpm, and reacted in an ice-water bath in the dark for 4 h;

[0119] After the reaction, dialysis was carried out in the dark at 4 °C for 48 h, frozen overnight at -80 °C and then freeze-dried for 72 h to obtain thiolated gelatin.

[0120] The chelating agent is imidazole. The modifier is 4-butyl mercaptolactone.

[0121] The dialysis is dialysis with a dialysis bag, and the cut-off molecular weight of the dialysis bag is 3500 Da.

[0122] The dialysis is carried out using a cysteine solution, and the concentration of the cysteine solution is 0.7 wt%.

[0123] A preparation method of a hydrogel adhesive based on gelatin and clay materials, comprising the following steps:

[0124] S1 Prepare a modified gelatin solution, and mix the modified gelatin solution with the modified clay material;

[0125] S2 Add a thiolated crosslinking agent and stir at 40 °C for 15 min;

[0126] S3 Add an initiator, mix for 15 min; carry out photocuring crosslinking to obtain a hydrogel adhesive.

[0127] The preparation method of the modified gelatin solution comprises the following steps: adding methacrylated gelatin to PBS at 60 °C, and the concentration of methacrylated gelatin is 5 wt%.

[0128] The concentration of the added modified clay material is 2 wt%.

[0129] The thiolated crosslinking agent accounts for 1.75% of the weight of the hydrogel adhesive.

[0130] The initiator is lithium phenyl-2,4,6-trimethylbenzoylphosphine.

[0131] The light for the photocuring crosslinking is blue-green light, the wavelength of the light is 450 - 550 nm, the curing time is 60 s, and the energy of the light is 100 mW / cm 2 .

[0132] The structural schematic diagram of the prepared hydrogel adhesive is shown inFigure 7 .

[0133] Example 2

[0134] A hydrogel adhesive based on gelatin and clay materials, the specific implementation method is the same as that of Example 1, the difference is that the modified gelatin is norbornene-modified gelatin.

[0135] The preparation method of the norbornene-modified gelatin includes the following steps:

[0136] Add 368 mg of 5-norbornene-2-carboxylic acid to 20 mL of buffer solution II to prepare a 5-norbornene-2-carboxylic acid solution;

[0137] Add an activator to the 7-norbornene-2-carboxylic acid solution and stir at 50 °C for 15 min for activation;

[0138] Add 1 g of gelatin (pre-dissolved in 10 mL of deionized water) to the activated 5-norbornene-2-carboxylic acid solution, and adjust the pH to 7.5 - 7.8 with sodium hydroxide to obtain a mixed reactant;

[0139] Stir the mixed reactant at 50 °C for 12 h and centrifuge at 2000 rpm for 3 min;

[0140] After centrifugation, the supernatant is dialyzed with deionized water for 72 h, frozen at -80 °C overnight, and then freeze-dried for 72 h to obtain norbornene-modified gelatin.

[0141] The buffer solution II is MES buffer solution with a concentration of 0.5 M and a pH of 6.

[0142] The activator is a combination of 1.02 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.31 g of N-hydroxysuccinimide (NHS).

[0143] The dialysis is dialysis with a dialysis bag, and the cut-off molecular weight of the dialysis bag is 3500 Da.

[0144] Comparative Example 1

[0145] A hydrogel adhesive based on gelatin and clay materials, the specific implementation method is the same as that of Example 1, the difference is that the concentration of the added modified clay material is 0 wt%.

[0146] Comparative Example 2

[0147] A hydrogel adhesive based on gelatin and clay materials, the specific implementation method is the same as that of Example 1, the difference is that the concentration of the added modified clay material is 1 wt%.

[0148] Comparative Example 3

[0149] A hydrogel adhesive based on gelatin and clay materials, with the specific implementation method being the same as that of Example 2, except that the concentration of the added modified clay material is 0 wt%.

[0150] Comparative Example 4

[0151] A hydrogel adhesive based on gelatin and clay materials, with the specific implementation method being the same as that of Example 2, except that the concentration of the added modified clay material is 1 wt%.

[0152] Comparative Example 5

[0153] A preparation method of a hydrogel adhesive, comprising the following steps:

[0154] Prepare a 5 wt% gelatin solution in PBS at 60 °C, and continuously stir at 40 °C and a rotation speed of 600 rpm for 15 minutes to obtain the hydrogel adhesive.

[0155] Comparative Example 6

[0156] A preparation method of a hydrogel adhesive, comprising the following steps:

[0157] Prepare a 5 wt% gelatin solution in PBS at 60 °C, mix the gelatin solution with the modified clay material, and continuously stir at 40 °C and a rotation speed of 600 rpm for 15 minutes to obtain the hydrogel adhesive.

[0158] The preparation method of the modified clay material is the same as that of Example 1.

[0159] The concentration of the added modified clay material is 1 wt%.

[0160] Comparative Example 7

[0161] A preparation method of a hydrogel adhesive, comprising the following steps:

[0162] Prepare a 5 wt% gelatin solution in PBS at 60 °C, mix the gelatin solution with the modified clay material, and continuously stir at 40 °C and a rotation speed of 600 rpm for 15 minutes to obtain the hydrogel adhesive.

[0163] The preparation method of the modified clay material is the same as that of Example 1.

[0164] The concentration of the added modified clay material is 2 wt%.

[0165] Performance testing

[0166] 1. NMR spectra: The comparative NMR pictures of the methacrylated gelatin and gelatin prepared in Example 1 are shown in Figure 1 , and the comparative NMR pictures of the methacrylated gelatin and gelatin prepared in Example 2 are shown in Figure 2 .

[0167] As can be seen from the figure: 1. Compared with gelatin, for methacrylated gelatin, a peak of carbon-carbon double bond appears near 5.55 ppm in the NMR spectrum, and the peak of -NH2 at 2.85 ppm decreases significantly, indicating that the methacrylic acid group has been successfully grafted onto gelatin. 2. Compared with gelatin, for norbornene-modified gelatin, an olefin peak appears at 6.25 ppm and a proton peak of tertiary carbon appears at 3.25 ppm in the NMR spectrum, indicating that the norbornene group has been successfully grafted onto gelatin.

[0168] 2. Infrared spectrum: The infrared spectra of methacrylated gelatin prepared in Example 1, norbornene-modified gelatin prepared in Example 2, and thiolated gelatin prepared in Example 1 are shown in Figure 3 , from left to right are: methacrylated gelatin, norbornene-modified gelatin, and thiolated gelatin.

[0169] As can be seen from the figure: For methacrylated gelatin, an increase in peak intensity appears at 1640 - 1660 cm-1, which is the stretching vibration peak of C=C. In addition, changes in peak intensity appear at 2800 cm-1 and 520 cm-1, indicating that the methacryloyl group has been successfully introduced into the gelatin molecule. 2. For norbornene-modified gelatin, an enhancement of the peak appears around 1600 cm -1 , which is the stretching vibration absorption peak of the C=C bond; an enhancement of the peak appears at 2800 - 2950 cm -1 , which is the stretching vibration absorption peak of the C-H bond. In addition, a change in peak intensity appears at 1500 cm -1 , indicating that norbornene has been successfully grafted onto gelatin. 3. For thiolated gelatin, a new peak appears at 2300 cm -1 , corresponding to the stretching vibration of -SH. In addition, changes in peak intensity appear at 1510 cm -1 and 1 - 30 cm -1 , indicating that the mercapto group has been successfully grafted onto gelatin.

[0170] 3. Verification test for the successful preparation of polydopamine-modified montmorillonite: The actual preparation process pictures of polydopamine-modified montmorillonite are shown in Figure 4 , the infrared spectrum of polydopamine-modified montmorillonite is shown in Figure 5 , the ultraviolet spectrum of polydopamine-modified montmorillonite is shown in Figure 6 .

[0171] As can be seen from the figure: After montmorillonite is added to the dopamine solution, the solution changes from transparent light brown to opaque light milky yellow, and as the reaction time increases, the solution color deepens and turns into dark black, indicating that dopamine polymerizes to form black polydopamine. And the product shows light yellow powder after freeze-drying, indicating that there is black polydopamine on the montmorillonite. 2. The infrared picture shows that polydopamine (PDA) is at 3100 - 3600 cm -1A broad peak appears, which is the stretching vibration peak of phenolic hydroxyl (-OH), amino (-NH), and imino (-NH). At 1310 cm -1 C-N bending vibration peak, 1525 cm -1 Characteristic absorption peak of N-H shear vibration, and the peak intensity of the benzene ring C═C stretching vibration peak at 1620 cm -1 weakens, indicating that dopamine self-polymerizes to form polydopamine in solution. The dopamine-modified montmorillonite shows characteristic peaks of hydroxyquinoline at 1580 cm -1 , 1500 cm -1 and 1470 cm -1 , and an asymmetric stretching vibration peak of methyl appears at 2920 cm -1 , indicating that polydopamine is grafted onto montmorillonite. 3. The UV spectrum shows that the shift of the maximum absorption peaks at 203 and 282 nm is caused by aromatic groups, indicating the formation of 5,6-dihydroxyindole. The peak shift from 278 - 282 nm indicates the polymerization of Dopa into polydopamine (PDA). In addition, the polydopamine-modified montmorillonite (PDA-clay) has a slight red shift at 203 - 216 nm and an absorption peak appears at 278 nm, which indicates the formation of polydopamine.

[0172] 4. Photographs of the prepared hydrogel adhesives. For the hydrogel adhesives prepared in Example 1 and Comparative Examples 1 - 2, see Figure 8 , upper layer: front view, lower layer: top view. From left to right: Comparative Example 2, Comparative Example 1, Example 1. For the hydrogel adhesives prepared in Example 2 and Comparative Examples 3 - 4, see Figure 9 , upper layer: front view, lower layer: top view. From left to right: Comparative Example 4, Comparative Example 3, Example 2.

[0173] It can be seen from the figure that all materials can form gels. And as the concentration of PDA-clay increases, the color of the hydrogel gradually deepens, changing from colorless and transparent to light brown.

[0174] 5. Adhesion test: Using fresh pigskin, fix the skin on a glass plate with glue, apply 250 μL of the uncured hydrogel adhesive prepared in Example 1 on the pigskin, and then irradiate with ultraviolet light for 60 s. Measure the adhesion strength of the sample at the tear point with a strain rate of 50 mm / min. The point force-strain curve is shown in Figure 13 . Photographs of the adhesion test of the hydrogel adhesive on pigskin are shown in Figure 10 , photographs of the adhesion test of the hydrogel adhesive on fingers are shown in Figure 11 , photographs of the torsional test of the hydrogel adhesive on pigskin are shown in Figure 12 . The point force-strain curves of the hydrogel adhesives prepared in Example 1 and Comparative Examples 1 - 2 on pigskin are shown inFigure 13 。

[0175] As can be seen from the figure, the adhesive has good adhesion effects on both pigskin and human skin, and the above adhesion remains unchanged under torsion. Further adhesion mechanics tests show that the adhesive has a certain adhesion effect, and Example 1 has the maximum adhesion force, which can reach 20.36 Pa.

[0176] 6. Hemolysis test: The steps are as follows:

[0177] 6.1. Prepare a hydrogel (Φ6.58 mm × H 6 mm, i.e., 200 μL);

[0178] 6.2. Mix 0.4 mL of anticoagulated blood with 19.6 mL of PBS solution;

[0179] 6.3. Incubate 4 mL of water-diluted blood together with the hydrogel samples of Example 1, 2, and Comparative Examples 1-4 at 37 °C for 1 hour;

[0180] 6.4. After the incubation, take out the hydrogel, centrifuge the solution (3000 rpm, 15 minutes), and separate the supernatant and red blood cell precipitate;

[0181] 6.5. Use a microplate reader to measure the absorbance value of the supernatant at a wavelength of 540 nm;

[0182] 6.7. Calculate the hemolysis rate.

[0183] Use 4 mL of water-diluted blood as the positive control, and 4 mL of blood diluted with PBS solution as the negative control.

[0184] Hemolysis rate (%) = [(Aexperimental group - Anegative control) / (Apositive control - Anegative control)] × 100%. Wherein, Aexperimental group, Anegative control, and Apositive control are the absorbance values of the experimental group, negative control, and positive control, respectively.

[0185] Photos of the hemolysis experiment are shown in Figure 14 , and as can be seen from the figure: The positive control group appears red, which is due to the presence of ruptured red blood cells. The negative control group and the experimental group are almost transparent and colorless. In addition, the results of the ultraviolet absorption spectrum show that the hemolysis rate of all experimental group solutions is within 5%, indicating that the hydrogel does not cause obvious hemolysis reactions.

[0186] The bar chart of the hemolysis rate tested in the hemolysis experiment is shown in Figure 16 。

[0187] 7. Coagulation experiment test: The steps are as follows:

[0188] 7.1. Mix 500 μL of anticoagulated blood and 50 μL of CaCl2 solution (0.1 M) to obtain a mixed solution;

[0189] 7.2. Prepare hydrogels (Φ6.58 mm × H 6 mm, i.e., 200 μL);

[0190] 7.3. Drop 50 μL of the mixed solution onto the surfaces of the hydrogels and blank Petri dishes;

[0191] 7.4. Incubate all samples at 37 °C for 5 minutes;

[0192] 7.5. Disperse the uncoagulated blood with 5 mL of PBS, and keep the clot as intact as possible during this process;

[0193] 7.6. Test the OD value at 540 nm with an ELISA reader.

[0194] Use deionized water as the control group.

[0195] The blood coagulation index (BCI) is calculated by the following formula: BCI (%) = (Aexperimental group - Adeionized water) / (Ablank Petri dish group - Adeionized water) × 100%.

[0196] Photos of the blood coagulation experiment are shown in Figure 15 , and it can be seen from the figure that there is no blood coagulation in the blank Petri dish group, while partial blood has coagulated in the experimental group. In addition, the results of the ultraviolet absorption spectra (blood coagulation index, BCI) show that as the concentration of PDA-clay increases, the BCI of the solution becomes lower, indicating that the degree of blood coagulation increases with the increase in the concentration of PDA-clay. Moreover, there are significant differences in the blood content in the solutions of Example 1 and Example 2 compared with the blank Petri dish group, indicating that they have significantly better blood coagulation performance.

[0197] The bar chart of the blood coagulation index tested in the blood coagulation experiment is shown in Figure 17 .

[0198] 8. Gel-forming property test: Place the hydrogel adhesives prepared in Comparative Examples 5-7 in vials and let them stand for 10 min. Verify whether gel formation occurs by the vial inversion method. Test pictures are shown in Figure 18 and 19 .

[0199] The results show that as the concentration of PDA-clay increases, the color of the solution gradually becomes darker. After inverting the test tube, the solution in the tube immediately slides down. The above materials do not have gel-forming properties and therefore cannot be used as wound adhesives.

Claims

1. A hydrogel adhesive based on gelatin and clay materials, characterized in that, The preparation raw materials at least include modified gelatin, modified clay material and thiolated crosslinking agent.

2. The hydrogel adhesive based on gelatin and clay materials according to claim 1, wherein The preparation raw materials further include an initiator. The thiolated crosslinking agent is thiolated gelatin, and the thiolated crosslinking agent accounts for 0 - 15% (excluding 0%) of the weight of the hydrogel adhesive.

3. The hydrogel adhesive based on gelatin and clay materials according to claim 1, characterized in that, The modified gelatin is acrylic acid modified gelatin, and the acrylic acid modified gelatin includes at least one of methacrylated gelatin, norbornene modified gelatin or glycidyl methacrylate modified gelatin.

4. The hydrogel adhesive based on gelatin and clay materials according to claim 3, characterized in that, The acrylic acid modified gelatin accounts for 3 - 30% of the weight of the hydrogel adhesive.

5. The hydrogel adhesive based on gelatin and clay materials according to claim 3, characterized in that, The weight ratio of the acrylic acid modified gelatin to the modified clay material is (3 - 30):(0 - 10) (excluding 0).

6. The hydrogel adhesive based on gelatin and clay materials according to claim 3, characterized in that, The preparation method of the methacrylated gelatin includes the following steps: Add gelatin into buffer solution I to obtain a gelatin solution. Add methacrylic anhydride into the gelatin solution and mix to obtain a mixed solution. The mixed solution is stirred at 200 - 400 rpm for 2 - 5 h in an environment of 30 - 50 °C for reaction. After the reaction is completed, add buffer solution I to terminate the reaction, dialyze for 48 - 72 h, freeze, and lyophilize to obtain methacrylated gelatin.

7. The hydrogel adhesive based on gelatin and clay materials according to claim 3, characterized in that, The preparation method of the norbornene modified gelatin includes the following steps: Add 5 - norbornene - 2 - carboxylic acid into buffer solution II to obtain a 5 - norbornene - 2 - carboxylic acid solution. Add an activator to the 5 - norbornene - 2 - carboxylic acid solution and stir at 40 - 60 °C for 10 - 20 min for activation. Add gelatin into the activated 5 - norbornene - 2 - carboxylic acid solution and adjust the pH to 7.5 - 7.8 to obtain a mixed reactant. Stir the mixed reactant at 40 - 60 °C for 10 - 15 h and centrifuge at 1500 - 2500 rpm for 1 - 5 min. After centrifugation, dialyze the supernatant with deionized water for 48 - 72 h, freeze, and lyophilize to obtain norbornene modified gelatin.

8. The hydrogel adhesive based on gelatin and clay materials according to claim 2, wherein The preparation method of the thiolated gelatin includes the following steps: Add gelatin into deionized water to obtain a gelatin solution, and purge with inert gas. Add a chelating agent into deionized water to obtain a chelating agent solution. Add the chelating agent solution and a modifier into the gelatin solution purged with inert gas, stir at 500 - 800 rpm, and react in an ice - water bath in the dark for 3 - 5 h. After the reaction, dialyze in the dark for 48 - 72 h, freeze, and lyophilize to obtain thiolated gelatin.

9. A method for preparing a hydrogel adhesive based on gelatin and clay materials according to any one of claims 2-8, characterized in that, It includes the following steps: S1 Prepare a modified gelatin solution, and mix the modified gelatin solution with the modified clay material. S2 Add the thiolated crosslinking agent and stir at 30 - 50 °C for 10 - 20 min. S3 Add the initiator, mix for 5 - 10 min; perform photocuring crosslinking to obtain the hydrogel adhesive.

10. The preparation method of the hydrogel adhesive based on gelatin and clay materials according to claim 9, characterized in that, The light for the photocuring crosslinking is ultraviolet light or visible light. The wavelength of the light is 320 - 450 nm, and the curing time is 10 - 120 s.

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