Low-swelling and asymmetric-adhesion Janus hydrogel as well as preparation method and application thereof

Abstract

The invention discloses low-swelling and asymmetric-adhesion Janus hydrogel as well as a preparation method and application of the low-swelling and asymmetric-adhesion Janus hydrogel. The raw materials of the hydrogel comprise a surfactant, a hydrophilic monomer, a hydrophobic monomer, PABA, natural polyphenol and a photoinitiator. The preparation method comprises the following steps: dissolving a surfactant and a hydrophilic monomer in water, then adding a hydrophobic monomer, PABA and natural polyphenol, uniformly mixing at a certain stirring speed, then adding a photoinitiator to obtain a hydrogel precursor emulsion, and cross-linking under ultraviolet light to obtain the hydrogel. The hydrogel provided by the invention forms a nano-scale micro-phase separation structure through electrostatic interaction of internal carboxyl and quaternary ammonium salt groups, so that the swelling behavior of the hydrogel can be effectively inhibited, the hydrogel has a relatively low swelling rate, and internal mechanical properties are enhanced; meanwhile, the hydrogel has remarkable asymmetric adhesion performance, one side has strong adhesion, the other side has weak adhesion, and postoperative adhesion is expected to be avoided while wound tissues are repaired.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and particularly relates to a low-swelling and asymmetric adhesion Janus hydrogel and its preparation method and application. Background Art

[0002] At present, in order to promote wound healing clinically, the most commonly used method is surgical suture, especially for internal wounds that are difficult to handle. However, surgical suture has problems such as time-consuming, easy to cause secondary bleeding, secondary damage to tissues, and postoperative adhesions. Compared with traditional surgical sutures, commercial tissue adhesives, such as fibrin-based, cyanoacrylate-based, and polyethylene glycol-based bio-glues, exhibit the advantages of being portable, minimally invasive, and easy to use. However, these adhesives generally have problems such as weak adhesion strength, poor adhesion stability, or poor biocompatibility. In recent years, hydrogel-based bioadhesives have received extensive attention due to their appropriate mechanical compatibility with tissues and excellent biocompatibility. Compared with skin wound healing, due to the extremely complex in vivo environment, it is more challenging to develop effective hydrogel bioadhesives for repairing internal soft tissue defects.

[0003] Specifically, the biggest challenge in in vivo wound repair is the mutual contact of wet tissue surfaces and different organs in a continuously dynamic in vivo environment, such as the abdominal cavity and thoracic cavity. When exposed to the body fluid environment for a long time, the mechanical properties of most hydrogels will decrease sharply due to network swelling, further leading to a loss of adhesion strength. This requires that the hydrogel should have a low swelling rate and adhesion stability under physiological conditions. At the same time, in order to promote tissue repair and avoid postoperative adhesions, the side of the hydrogel adjacent to the damaged tissue should have good bioadhesion and bioactivity to provide mechanical support and a favorable microenvironment for tissue repair; the other side is preferably non-adhesive to the surrounding tissues to physically prevent the formation of fibrotic scars. Although various Janus hydrogels have been prepared, such as the unilateral ion sealing method, solvent immersion method, and multi-layer composite processing method. However, most of them have problems such as time-consuming preparation processes, weak interlayer adhesion, low mechanical strength, and poor adhesion stability, which severely limit their practical applications and large-scale production. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a low-swelling and asymmetric adhesion Janus hydrogel and its preparation method and application.

[0005] The technical solution adopted by the present invention is as follows:

[0006] I. A low-swelling and asymmetric adhesion Janus hydrogel:

[0007] The raw materials of the Janus hydrogel include water, surfactant, hydrophilic monomer, hydrophobic monomer, phenylboronic acid group, quaternary ammonium salt group, allyl-functionalized polyphosphazene, natural polyphenol, and photoinitiator;

[0008] The hydrophilic monomer is a free-radical polymerizable monomer containing a double bond;

[0009] The hydrophobic monomer is a free-radical polymerizable monomer containing a hydrophobic group.

[0010] The Janus hydrogel is mainly composed of the following raw materials in parts by mass: 0.1 - 2 parts of surfactant, 5 - 20 parts of hydrophilic monomer, 0.1 - 1 part of hydrophobic monomer, 0.1 - 1 part of phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene, 0.01 - 0.5 part of natural polyphenol, 0.01 - 0.1 part of photoinitiator, and 10 - 30 parts of deionized water.

[0011] The hydrophilic monomer is one or a combination of acrylic acid and methacrylic acid;

[0012] The hydrophobic monomer is one or a combination of acrylate hydrophobic monomers and styrene hydrophobic monomers. Further preferably, it is lauryl methacrylate (LMA).

[0013] The Janus hydrogel uses a polymer network formed by free-radical polymerization of hydrophilic and hydrophobic monomers as the mechanical dissipation and adhesion components; the semi-interpenetrating polymer network composed of phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene and natural polyphenol is used as the anti-swelling component. This hydrogel forms a nano-scale microphase separation structure through the electrostatic interaction between internal carboxyl groups and quaternary ammonium salt groups, which can effectively inhibit its swelling behavior, have a low swelling rate, and enhance the internal mechanical properties.

[0014] The phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene PABA is specifically poly[(N,N,N,N-dimethylaminoethyl p-methylphenylboronic acid bromide)-g-(N,N,N,N-dimethylaminoethyl allyl bromide)] phosphazene, where g represents graft. And the grafting rates of the phenylboronic acid group, quaternary ammonium salt group and allyl in the phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene PABA are 15 - 30%, 100%, and 70 - 85% respectively.

[0015] Among them, the phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene PABA is mainly synthesized from the following raw materials in parts by mass: 1 - 10 parts of poly(N,N-dimethyl-1,2-ethylenediamine) phosphazene, 0.1 - 5 parts of 3-bromomethylphenylboronic acid, 1 - 20 parts of allyl bromide, and 10 - 1000 parts of anhydrous methanol.

[0016] Among them, the synthesis route of the polyphosphazene PABA functionalized with phenylboronic acid group, quaternary ammonium salt group and allyl includes the following steps: First, dissolve poly(N,N-dimethyl-1,2-ethylenediamine) phosphazene in anhydrous methanol in a flask according to the above mass parts. Second, add 3-bromomethylphenylboronic acid according to the above mass parts and react at room temperature for 24 h. Third, add allyl bromide according to the above mass parts and continue to react at room temperature for 24 h to obtain a crude product. Finally, the crude product is dialyzed in 3-5 L of deionized water for 3-5 days and then obtained by freeze-drying the polyphosphazene PABA functionalized with phenylboronic acid group, quaternary ammonium salt group and allyl.

[0017] Among them, the grafting rates of the phenylboronic acid group, quaternary ammonium salt group and allyl in the polyphosphazene PABA functionalized with phenylboronic acid group, quaternary ammonium salt group and allyl are 15-30%, 100% and 70-85% respectively.

[0018] Among them, the structural formula of the polyphosphazene PABA functionalized with phenylboronic acid group, quaternary ammonium salt group and allyl is as follows:

[0019]

[0020] Among them, n = 1000-100000, and the grafting rates of different groups are x / n = 70%-85%; y / n = 15%-30% in turn.

[0021] The natural polyphenol is one or a combination of more than one of tannic acid, gallocatechin and epigallocatechin gallate, and is further preferably epigallocatechin gallate (EGCG).

[0022] The photoinitiator is one or more of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, ethyl 2,4,6-trimethylbenzoyl phenylphosphinate and lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and is further preferably lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP).

[0023] II. A preparation method of a low-swelling and asymmetrically adhesive Janus hydrogel:

[0024] The preparation method includes the following steps: Dissolve a surfactant and a hydrophilic monomer in water at 25-60 °C, then add a hydrophobic monomer, a natural polyphenol and the polyphosphazene functionalized with phenylboronic acid group, quaternary ammonium salt group and allyl, and mix them evenly at a certain stirring rate. Subsequently, add a photoinitiator to obtain a hydrogel precursor emulsion, and crosslink it under ultraviolet light to obtain the hydrogel.

[0025] The stirring rate is 100-1500 rpm, and the mixing and stirring time is 1-6 hours.

[0026] The cross-linking time is 5 to 60 minutes.

[0027] Application of the low-swelling and asymmetrically adhesive Janus hydrogel in the preparation of tissue trauma repair materials.

[0028] The hydrogel provided by the present invention forms a nano-scale microphase separation structure through the electrostatic interaction between internal carboxyl groups and quaternary ammonium salt groups, which can effectively inhibit its swelling behavior, has a low swelling rate and realizes enhanced internal mechanical properties; at the same time, the hydrogel has significant asymmetric adhesion performance, with strong adhesion on one side and weak adhesion on the other side, and is expected to avoid postoperative adhesions while repairing traumatic tissues.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. The present invention utilizes the buoyancy difference of emulsion droplets of different sizes in an aqueous solution to construct the asymmetric adhesion of the hydrogel. Its one-piece molding process avoids the problems of time-consuming preparation procedures and poor interlayer adhesion caused by existing multi-layer composite processing methods, providing a new option for the repair of traumatic tissues in vivo in complex environments.

[0031] 2. The hydrogel of the present invention can be cured into a gel without adding any cross-linking agent, avoiding the potential tissue toxicity problems brought by cross-linking agents. In addition, the hydrogel forms a nano-scale microphase separation structure through the electrostatic interaction between internal carboxyl groups and quaternary ammonium salt groups, which can effectively inhibit its swelling behavior, has a low swelling rate and realizes enhanced internal mechanical properties, thereby providing good adhesion stability. Description of the Drawings

[0032] Figure 1 It is a graph showing the swelling performance test results of the hydrogels prepared in Comparative Example 1 and Example 1.

[0033] Figure 2 It is a graph showing the 1D SAXS test results of the hydrogels prepared in Examples 1 to 4.

[0034] Figure 3 It is a graph showing the XPS test results of the C1s region on the top and bottom surfaces of the hydrogel prepared in Example 1.

[0035] Figure 4 It is a graph showing the XPS test results of the N1s region on the top and bottom surfaces of the hydrogel prepared in Example 1.

[0036] Figure 5 It is a graph showing the tensile property test results of the hydrogels prepared in Examples 1 to 4.

[0037] Figure 6Test result graphs of the adhesion energy of the top and bottom surfaces of the hydrogels prepared in Examples 1 to 4. Detailed implementation manners

[0038] The present invention will be described in more detail below with reference to the accompanying drawings and examples. However, the present invention is not limited thereto. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as within the protection scope of the present invention. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0039] Examples and comparative examples of the present invention are as follows:

[0040] Example 1

[0041] Preparation of a low-swelling and asymmetric adhesion Janus hydrogel (PABA-EGCG-ALC-0h), including the following steps:

[0042] First, 0.3592 g of surfactant cetyltrimethylammonium bromide (CTAB) was completely dissolved in 5.0 mL of deionized water at 40 °C. After stirring for 10 min, 3.0398 g of acrylic acid (AA), 0.1498 g of lauryl methacrylate (LMA), 0.4125 g of poly[(N,N,N,N-dimethylaminoethyl p-methylphenylboronic acid ammonium bromide)-g-(N,N,N,N-dimethylaminoethyl allyl ammonium bromide)] phosphazene (PABA), and 0.0686 g of epigallocatechin gallate (EGCG) were successively added to the above solution, and stirred with a magnetic stirrer at a speed of 1000 RPM for 4 h. Subsequently, 0.0068 g of photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) was added and continuously stirred at 1000 rpm for 5 min to form a hydrogel precursor emulsion. The obtained precursor emulsion was poured into a polytetrafluoroethylene mold, and the upper surface was covered with a glass slide, and crosslinked and cured under 100 W ultraviolet light for 10 min. The demolded hydrogel was not treated, and finally a low-swelling and asymmetric adhesion Janus hydrogel (PABA-EGCG-ALC-0h) was obtained.

[0043] The emulsion droplet size of the obtained hydrogel precursor emulsion was 80 - 160 μm.

[0044] Example 2

[0045] Preparation of a low-swelling and asymmetric adhesion Janus hydrogel (PABA-EGCG-ALC-1h), including the following steps:

[0046] First, 0.3592 g of the surfactant cetyltrimethylammonium bromide (CTAB) was completely dissolved in 5.0 mL of deionized water at 40 °C. After stirring for 10 min, 3.0398 g of acrylic acid (AA), 0.1498 g of lauryl methacrylate (LMA), 0.4125 g of poly[(N,N,N,N-dimethylaminoethyl p-methylphenylboronic acid ammonium bromide)-g-(N,N,N,N-dimethylaminoethyl allylammonium bromide)] phosphazene (PABA), and 0.0686 g of epigallocatechin gallate (EGCG) were successively added to the above solution, and stirred with a magnetic stirrer at a speed of 1000 RPM for 4 h. Subsequently, 0.0068 g of the photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) was added and continuously stirred at 1000 rpm for 5 min to form a hydrogel precursor emulsion. The obtained precursor emulsion was poured into a polytetrafluoroethylene mold, the upper surface was covered with a glass sheet, crosslinked and cured under 100 W ultraviolet light for 10 min, and the demolded hydrogel was immersed in phosphate buffered saline (PBS; pH = 7.4) for 1 h and then taken out to finally obtain a low-swelling and asymmetrically adhesive Janus hydrogel (PABA-EGCG-ALC-1h).

[0047] The emulsion droplet size of the obtained hydrogel precursor emulsion was 80 - 160 μm.

[0048] Example 3

[0049] Preparation of a low-swelling and asymmetrically adhesive Janus hydrogel (PABA-EGCG-ALC-8h), comprising the following steps:

[0050] First, 0.3592 g of the surfactant cetyltrimethylammonium bromide (CTAB) was completely dissolved in 5.0 mL of deionized water at 40 °C. After stirring for 10 min, 3.0398 g of acrylic acid (AA), 0.1498 g of lauryl methacrylate (LMA), 0.4125 g of poly[(N,N,N,N-dimethylaminoethyl p-methylphenylboronic acid ammonium bromide)-g-(N,N,N,N-dimethylaminoethyl allyl ammonium bromide)] phosphazene (PABA), and 0.0686 g of epigallocatechin gallate (EGCG) were sequentially added to the above solution, and the mixture was stirred with a magnetic stirrer at a speed of 1000 RPM for 4 h. Subsequently, 0.0068 g of the photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) was added and the mixture was continuously stirred at 1000 rpm for 5 min to form a hydrogel precursor emulsion. The obtained precursor emulsion was poured into a polytetrafluoroethylene mold, the upper surface was covered with a glass slide, and it was cross-linked and cured under 100 W ultraviolet light for 10 min. The demolded hydrogel was taken out after being soaked in phosphate buffered saline (PBS; pH = 7.4) for 8 h, and finally, a low-swelling and asymmetrically adhesive Janus hydrogel (PABA-EGCG-ALC-8h) was obtained.

[0051] The emulsion droplet size of the obtained hydrogel precursor emulsion was 80 - 160 μm.

[0052] Example 4

[0053] Preparation of a low-swelling and asymmetrically adhesive Janus hydrogel (PABA-EGCG-ALC-72h), comprising the following steps:

[0054] First, 0.3592 g of the surfactant cetyltrimethylammonium bromide (CTAB) was completely dissolved in 5.0 mL of deionized water at 40 °C. After stirring for 10 min, 3.0398 g of acrylic acid (AA), 0.1524 g of lauryl methacrylate (LMA), 0.4125 g of poly[(N,N,N,N-dimethylamineethyl p-methylbenzeneboronic acid ammonium bromide)-g-(N,N,N,N-dimethylamineethyl allylammonium bromide)] phosphazene (PABA), and 0.0686 g of epigallocatechin gallate (EGCG) were successively added to the above solution, and stirred with a magnetic stirrer at 1000 RPM for 4 h. Subsequently, 0.0068 g of the photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) was added and continuously stirred at 1000 rpm for 5 min to form a hydrogel precursor emulsion. The obtained precursor emulsion was poured into a polytetrafluoroethylene mold, the upper surface was covered with a glass slide, crosslinked and cured under 100 W ultraviolet light for 10 min, and the hydrogel after demolding was soaked in phosphate buffered saline (PBS; pH = 7.4) for 72 h and then taken out, finally obtaining a low-swelling and asymmetrically adhesive Janus hydrogel (PABA-EGCG-ALC-72h).

[0055] The emulsion droplet size of the obtained hydrogel precursor emulsion was 80 - 160 μm.

[0056] Comparative Example 1

[0057] The preparation of the asymmetrically adhesive Janus hydrogel (ALC) includes the following steps:

[0058] First, 0.3482 g of the surfactant cetyltrimethylammonium bromide (CTAB) was completely dissolved in 5.0 mL of deionized water at 40 °C. After stirring for 10 min, 3.0524 g of acrylic acid (AA) and 0.1521 g of lauryl methacrylate (LMA) were successively added to the above solution, and stirred with a magnetic stirrer at 1000 RPM for 4 h. Subsequently, 0.0069 g of the photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) was added and continuously stirred at 1000 rpm for 5 min to form a hydrogel precursor emulsion. The obtained precursor emulsion was poured into a polytetrafluoroethylene mold, the upper surface was covered with a glass slide, crosslinked and cured under 100 W ultraviolet light for 10 min, and the hydrogel after demolding was not treated, finally obtaining the asymmetrically adhesive Janus hydrogel (ALC).

[0059] The emulsion droplet size of the obtained hydrogel precursor emulsion was 80 - 160 μm.

[0060] Effect verification

[0061] The swelling properties of the hydrogels prepared in Comparative Example 1 and Example 1 were tested as follows:

[0062] To evaluate the swelling properties of the hydrogels, cylindrical hydrogels with a diameter of 10 mm and a height of 10 mm were immersed in 50 mL of phosphate buffered saline (PBS; pH = 7.4) at a temperature of 37 °C. At each predetermined time point, the soaked samples were taken out and weighed. The swelling ratio was calculated according to the following formula:

[0063]

[0064] where w0 is the weight of the original hydrogel, and w t is the weight of the swollen hydrogel at different time points. Figure 1 Figure showing the swelling property test results of the hydrogels prepared in Comparative Example 1 and Example 1. After 72 h, the swelling ratios of the hydrogels prepared in Comparative Example 1 and Example 1 were 188.7 ± 9.8% and 37.2 ± 5.4%, respectively. Since the hydrogel prepared in Example 1 introduced an interpenetrating polymer network-like structure composed of phenylboronic acid groups, quaternary ammonium salt groups, allyl-functionalized polyphosphazene and natural polyphenols, there was an electrostatic interaction between the carboxyl groups and quaternary ammonium salt groups inside it, and the formed nano-scale microphase separation structure could effectively inhibit its swelling behavior.

[0065] The phase separation behavior of the hydrogels prepared in Examples 1 to 4 was tested as follows:

[0066] The microscopic structure data of the hydrogels were tested using a small-angle X-ray scattering instrument (SAXS, Xeuss 2.0), and the X-ray wavelength was The distance from the sample to the detector was 1188 mm. Figure 2 Figure showing the 1D SAXS test results of the hydrogels prepared in Examples 1 to 4. As the swelling time increased, a gradually enhanced broad scattering peak appeared in the 1D scattering intensity curve of the hydrogels at the scattering vector (q = 0.198 nm -1 ), indicating that a nano-scale microphase separation structure was gradually formed through the electrostatic interaction between the internal carboxyl groups and quaternary ammonium salt groups, and the characteristic size of the phase separation was 31.7 nm.

[0067] The asymmetric chemical structure of the hydrogels prepared in Examples 1 to 4 was tested as follows:

[0068] The chemical compositions of the top and bottom surfaces of the hydrogels were measured using an X-ray photoelectron spectrometer (XPS) (Thermo Scientific ESCALAB 250Xi, X-ray energy 1486.6 eV, transfer energy: 20 eV, step energy: 0.05 eV). Figure 3XPS test result diagrams of the C1s region on the top and bottom surfaces of the hydrogel prepared in Example 1. Figure 4 XPS test result diagrams of the N1s region on the top and bottom surfaces of the hydrogel prepared in Example 1. The intensities of C=O (288.9 eV) and C-O (286.4 eV) on the bottom surface of the hydrogel prepared in Example 1 are increased compared to the top surface, while the intensity of C-N (285.7 eV) is decreased compared to the top surface. At the same time, the intensity difference between -N quat R3 (401.8 eV) and -NR2 (399.6 eV) is smaller compared to the top surface. It indicates that there is an electrostatic interaction between carboxyl groups (-COOH) and quaternary ammonium salt groups (-N quat R3) inside the hydrogel network; there are more carboxyl groups (-COOH) on its bottom surface compared to the top surface, thus realizing the asymmetry of adhesion.

[0069] The tensile properties of the hydrogels prepared in Examples 1 to 4 were tested as follows:

[0070] The tensile test was carried out by a universal tensile-compression testing machine (Instron-2kN). The hydrogels prepared in Examples 1 to 4 were cut into dumbbell-shaped samples (3 mm thick, 2 mm wide, and 35 mm long). The tensile rate was fixed at 100 mm / min. Figure 5 Tensile property test result diagrams of the hydrogels prepared in Examples 1 to 4. With the increase of the swelling time, the tensile strength and elongation at break of the hydrogel increased significantly, from 0.31 ± 0.04 MPa and 701.5 ± 113.6% to 0.90 ± 0.02 MPa and 1222.8 ± 50.0%. This shows that the hydrogel forms a nano-scale microphase separation structure through the electrostatic interaction between internal carboxyl groups and quaternary ammonium salt groups, which can effectively inhibit its swelling behavior and enhance the internal mechanical properties.

[0071] The asymmetric adhesion properties of the hydrogels prepared in Examples 1 to 4 were tested as follows:

[0072] 180° peel test: The hydrogels prepared in Comparative Example 1 and Examples 1 to 4 were cut into corresponding rectangular sizes (length 30 mm, width 20 mm, thickness 1 mm). A rigid polyethylene terephthalate (PET) film was used as the hydrogel backing and bonded to the non-test surface of the hydrogel with commercial 502 glue. The test surface of the hydrogel was adhered to the surface of fresh pigskin. After pressing for 30 s, a universal tensile-compression testing machine (500 N sensor, Zwick / Roell Z020) was used to conduct the test through a standard T-peel test (ASTM F2256). All tests were carried out at a constant peeling speed of 50 mm / min. When the peeling process entered a stable state, the measured force reached a steady state. The interfacial toughness of the hydrogel was obtained by dividing twice the plateau force by the width. Figure 6 It is a test result diagram of the adhesion energy of the top and bottom surfaces of the hydrogels prepared in Examples 1 to 4. With the increase of the swelling time, the asymmetric adhesion difference of the hydrogels did not change significantly (~5.0 times), indicating good adhesion stability.

[0073] The above is only the preferred specific implementation manner of the present invention, and the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A low-swelling and asymmetrically adhesive Janus hydrogel, characterized in that: The raw materials of the Janus hydrogel include water, surfactant, hydrophilic monomer, hydrophobic monomer, phenylboronic acid group, quaternary ammonium salt group, allyl-functionalized polyphosphazene, natural polyphenol and photoinitiator; The hydrophilic monomer is a free-radical polymerizable monomer containing a double bond; The hydrophobic monomer is a free-radical polymerizable monomer containing a hydrophobic group.

2. The Janus hydrogel with low swelling and asymmetric adhesion according to claim 1, characterized in that: The Janus hydrogel is mainly composed of the following raw materials in parts by mass: 0.1-2 parts of surfactant, 5-20 parts of hydrophilic monomer, 0.1-1 part of hydrophobic monomer, phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene 0.1-1 part, 0.01-0.5 part of natural polyphenol, 0.01-0.1 part of photoinitiator and 10-30 parts of deionized water.

3. The Janus hydrogel with low swelling and asymmetric adhesion according to claim 1, characterized in that: The hydrophilic monomer is one or a combination of acrylic acid and methacrylic acid; The hydrophobic monomer is one or a combination of acrylate hydrophobic monomers and styrene hydrophobic monomers.

4. The Janus hydrogel with low swelling and asymmetric adhesion according to claim 1, characterized in that: The phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene PABA is specifically poly[(N,N,N,N-dimethylaminoethyl p-methylphenylboronic acid ammonium bromide)-g-(N,N,N,N-dimethylaminoethyl allyl ammonium bromide)] phosphazene, and the grafting rates of the phenylboronic acid group, quaternary ammonium salt group and allyl are 15-30%, 100% and 70-85% respectively.

5. A low-swelling and asymmetrically adhesive Janus hydrogel according to claim 1, characterized in that: The natural polyphenol is one or a combination of tannic acid, gallocatechin and epigallocatechin gallate.

6. The low-swelling and asymmetrically adhesive Janus hydrogel according to claim 1, wherein: The photoinitiator is one or more of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, ethyl 2,4,6-trimethylbenzoyl phenylphosphinate and lithium phenyl-2,4,6-trimethylbenzoylphosphinate.

7. A preparation method of the low-swelling and asymmetrically adhesive Janus hydrogel as described in any one of claims 1-6, characterized in that: The preparation method includes the following steps: Dissolve the surfactant and hydrophilic monomer in water, then add the hydrophobic monomer, natural polyphenol, and phenylboronic acid group, quaternary ammonium salt group and allyl-functionalized polyphosphazene, and mix evenly at a certain stirring rate. Subsequently, add the photoinitiator to obtain a hydrogel precursor emulsion, and crosslink under ultraviolet light to obtain the hydrogel.

8. The preparation method of a Janus hydrogel according to claim 7, wherein: The stirring rate is 100-1500 rpm, and the mixing and stirring time is 1-6 hours.

9. The preparation method of a Janus hydrogel according to claim 7, characterized in that: The crosslinking time is 5-60 min.

10. Use of a low-swelling and asymmetrically adhesive Janus hydrogel as described in any one of claims 1 to 6 or a hydrogel obtained by a preparation method as described in any one of claims 7 to 8, characterized in that Application in the preparation of tissue wound repair materials.

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