CN112791227A

CN112791227A - Composite tissue adhesive and preparation method and application thereof

Info

Publication number: CN112791227A
Application number: CN202011631269.1A
Authority: CN
Inventors: 林丽敏; 唐东海; 邓坤学; 袁玉宇
Original assignee: Medprin Regenerative Medical Technologies Co Ltd
Current assignee: Medprin Regenerative Medical Technologies Co Ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2021-05-14
Anticipated expiration: 2040-12-30
Also published as: CN112791227B

Abstract

The invention discloses a composite tissue adhesive and a preparation method and application thereof. The composite tissue adhesive comprises a three-dimensional porous matrix and an enhanced adhesion factor adsorbed on the surface of the matrix, wherein the three-dimensional porous matrix is obtained by freeze-drying a composite hydrogel of methacrylic anhydride gelatin and polyacrylic acid grafted with N-hydroxysuccinimide, and the enhanced adhesion factor is polydopamine. The composite tissue adhesive has a porous structure, can absorb liquid for moistening a wound surface, and polyacrylic acid has carboxylic acid groups with negative charges, can accelerate the hydration expansion effect of the tissue adhesive and accelerate the drying speed of the tissue surface, so that the composite tissue adhesive has more than 500% of liquid absorption capacity, and the composite tissue adhesive has two components which can be bonded with amino groups on the wound surface tissue, and the adhesive strength with the tissue for moistening the wound surface can reach more than 180 kPa.

Description

Composite tissue adhesive and preparation method and application thereof

Technical Field

The invention relates to the technical field of wound surface adhesion, in particular to a composite tissue adhesive and a preparation method and application thereof.

Background

In a surgical operation, a larger wound usually needs a medical suture or nailing to perform anastomotic closure, and then in order to prevent blood leakage or infection of the wound, a tissue plugging glue (such as a dolomitic medical glue) or dressing and the like can be adopted to fill and close the gap, and for small gaps among tissues, the tissue plugging glue is directly adopted to close. However, clinical wound surfaces are often accompanied by continuous exudation of blood or tissue fluid, and leakage occurs, so that the wound surfaces are relatively moist. Although seepage is easy to clean at partial operation positions, the special parts such as deeper wound surfaces are difficult to clean, so that a tissue adhesive product capable of well treating wet wound surfaces is urgently needed. The tissue glue sold in the market at present has the problems of low adhesion strength or non-adhesion with tissues when used for moist wounds, and the problems of heat release and non-degradability of the glue under the moist condition, so that the requirements of closing and repairing the moist wounds in clinic cannot be well met.

CN106075553A discloses a biomedical adhesive and a preparation method thereof, which discloses a biomedical adhesive capable of generating cross-linking reaction with wound skin tissues, and the adhesive is prepared according to the following method: firstly, oxidizing sodium alginate with sodium periodate to prepare dialdehyde sodium alginate, dialyzing, drying, dissolving the product in MES buffer solution, then adding carboxymethyl chitosan, stirring and reacting for 6-12 h, then sequentially adding a certain amount of N-hydroxysuccinimide, 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and dopamine, stirring and reacting for 8-24 h under the protection of nitrogen, dialyzing, freeze-drying, and storing in a cool and dry place. Before use, the wound is pretreated by hydrogen peroxide, then the freeze-dried adhesive is dissolved by PBS buffer solution and immediately coated on the wound, and the wound can be bonded within 2-10 min. The adhesive has strong adhesive strength in a moist environment in vivo, good biocompatibility and biodegradability, and can effectively promote wound healing. However, the biomedical adhesive has the defects of poor self-mechanical strength, incapability of forming strong blockage on the wound surface, inconvenience in operation due to the need of dissolution before use and the like.

Therefore, the novel composite tissue adhesive which can be well adhered to tissues when used on a wet wound surface, has good mechanical strength and is convenient to use is developed, and the novel composite tissue adhesive has important significance for repairing the wet wound surface.

Disclosure of Invention

The invention aims to provide a composite tissue adhesive aiming at the defects that the tissue adhesive for repairing and adhering a wet wound surface in the prior art is low in tissue adhesive strength and the adhesive is lack of certain mechanical strength in the using process.

Another object of the present invention is to provide a method for preparing a composite tissue adhesive.

Still another object of the present invention is to provide a use of the composite tissue adhesive in preparing a wet wound adhesive product.

The above purpose of the invention is realized by the following technical scheme:

a composite tissue adhesive comprising a three-dimensional porous matrix and adhesion-enhancing factors adsorbed on the surface of the matrix, wherein the three-dimensional porous matrix is obtained by freeze-drying a composite hydrogel of methacrylic anhydridized gelatin and polyacrylic acid grafted with N-hydroxysuccinimide, and the adhesion-enhancing factors are polydopamine.

The action mechanism of the composite tissue adhesive of the invention is as follows: the composite tissue adhesive is in a dry state, does not need to be stored at low temperature and dissolved before use, when the composite tissue adhesive is used on a wet wound surface, the three-dimensional porous structure of the composite tissue adhesive can absorb liquid of the wet wound surface, so that the contacted wet wound surface can quickly form a dry wound surface, and meanwhile, polydopamine adsorbed by the three-dimensional porous structure of the composite tissue adhesive and N-hydroxysuccinimide (NHS) grafted on the composite tissue adhesive can be bonded with amino groups of the wound surface tissue, so that the composite tissue adhesive has strong tissue adhesion strength and is favorable for adhering and blocking the wound surface.

Furthermore, the composite tissue adhesive also comprises polylysine and/or polyethyleneimine, carboxyl groups of the polylysine and/or polyethyleneimine are connected with succinimide end groups of polyacrylic acid through peptide bonds, and the polylysine and/or polyethyleneimine and the polyacrylic acid form a polymer network structure, so that the wet mechanical strength of the composite tissue adhesive is further enhanced.

Furthermore, the polydopamine loading amount of the composite tissue adhesive is 10% (w/w) to 30% (w/w), and the grafting rate of polyacrylic acid grafted with N-hydroxysuccinimide (NHS) is 1% to 10%. The composite tissue adhesive has two adhesion factors of polydopamine and succinimide groups, and can be well used for adhesion plugging in a moist wound surface environment.

Furthermore, the liquid absorption of the composite tissue adhesive is more than or equal to 500 percent, and preferably 600 to 1500 percent; the wet mechanical strength is more than or equal to 50N, and the tissue adhesion strength is more than or equal to 180 kPa.

The invention also discloses a preparation method of the composite tissue adhesive, which comprises the following steps:

s1: uniformly mixing methacrylic acid anhydridized gelatin and polyacrylic acid or acrylic acid monomer, and carrying out N-hydroxysuccinimide grafting on the polyacrylic acid or acrylic acid monomer;

s2: carrying out photo-crosslinking on the mixture grafted in the S1 to form composite hydrogel;

s3: freezing the composite hydrogel in the S2 at low temperature, and performing first freeze-drying to obtain a spongy three-dimensional porous matrix;

s4: soaking the three-dimensional porous substrate in S3 in a dopamine-containing solution with the pH of 8-10, and soaking for not less than 20 hours under the condition of introducing oxygen; preferably, the pH value of the solution is 8.5, and the solution is soaked for 20-25 hours under the condition of introducing oxygen to obtain a composite tissue adhesive precursor;

s5: and (4) taking out the precursor of the composite tissue adhesive soaked in the S4, freezing for the second time at low temperature, then freeze-drying for the second time, and performing irradiation sterilization to obtain the composite tissue adhesive.

Among them, it should be noted that:

the methacrylic anhydridized gelatin in the S1 is prepared from methacrylic anhydride and gelatin, is a photosensitive biological hydrogel material, has excellent biocompatibility, can be excited by ultraviolet light or visible light to carry out curing reaction, and forms a three-dimensional structure which is suitable for cell growth and differentiation and has higher strength. The polyacrylic acid or acrylic acid monomer is grafted with N-hydroxysuccinimide (NHS), the modified succinimide group can react with amino on the tissue to enhance the tissue adhesion strength of the composite tissue adhesive and the moist wound surface, and the grafted NHS can be further bonded with other polymers to increase the self mechanical strength of the composite tissue adhesive. According to the invention, before methacrylic anhydrified gelatin forms hydrogel, the methacrylic anhydrified gelatin is uniformly mixed with polyacrylic acid or acrylic acid, so that polyacrylic acid grafted with NHS can be uniformly distributed in a gel product.

Preferably, the substitution rate of methacrylic acid in the methacrylic anhydride gelatin in S1 is more than or equal to 40%, and the higher the substitution rate of methacrylic acid is, the stronger the mechanical property of the composite tissue adhesive is.

Preferably, the grafting ratio of NHS grafting of the polyacrylic acid in S1 is 1% to 10%, and more preferably, the grafting ratio of NHS grafting of the polyacrylic acid is 3% to 10%.

Preferably, the mass of methacrylic anhydrified gelatin and polyacrylic acid or acrylic acid in S1 is 1: (1-100), wherein the ratio of 1: (50-100).

In S2, both methacrylic anhydrified gelatin and acrylic acid or polyacrylic acid can be independently crosslinked under the condition of light to form hydrogel. The methacrylic acid anhydridized gelatin enhances the mechanical strength of the polyacrylic acid hydrogel grafted with the N-hydroxysuccinimide; after a certain amount of N-hydroxysuccinimide is grafted on polyacrylic acid, the polyacrylic acid can react with amino on human tissues, and has certain adhesive strength.

Preferably, the photocrosslinkable crosslinking agent in S2 is I2959 uv initiator, LAP blue initiator or α -ketoglutaric acid; the addition amount of the crosslinking agent for photocrosslinking is 0.05-5% of the mass of the mixture after grafting.

In S3, the wet mechanical strength of the spongy three-dimensional porous matrix subjected to first freeze-drying is not less than 20N, the tissue adhesion strength is not less than 70kPa, the spongy three-dimensional porous matrix is frozen at low temperature and then freeze-dried, the porosity of the obtained three-dimensional porous structure is higher, the liquid absorption performance is better, so that more polydopamine can be adsorbed in the subsequent process.

In S4, dopamine can form polydopamine on the surface of the three-dimensional porous substrate under the conditions of alkalinity and oxygen supply, and the polydopamine can have good adhesion on wet tissue wound surfaces.

Preferably, the concentration of dopamine in the solution in S4 is 0.5 g/mL-6 g/mL.

Preferably, the solution in S4 has a pH of 8.5, and is soaked for 20-25 h under the condition of introducing oxygen.

Further preferably, the solution environment with pH8.5 is provided for preparation by using polyethyleneimine and polylysine as buffer pairs, wherein the polyethyleneimine and polylysine have primary amino groups and can react with a part of N-hydroxysuccinimide grafted by polyacrylic acid, so that a cross-linked network formed by the polyacrylic acid is further consolidated, and the wet mechanical strength of the composite tissue adhesive is enhanced.

Preferably, the solvent in the dopamine solution of S4 is a PBS buffer solution or a PBS-polyethyleneimine solution or a PBS-polylysine solution or a mixed solution of polylysine and polyethyleneimine.

In addition, the invention also specifically protects the application of the composite tissue adhesive in preparing a wet wound surface adhesive product.

Compared with the prior art, the invention has the beneficial effects that:

the composite tissue adhesive has a porous structure, can absorb liquid of a wet wound surface to enable the wet wound surface to quickly form a dry wound surface, and polyacrylic acid has carboxylic acid groups with negative charges, so that the hydration expansion effect of the tissue adhesive can be accelerated to a certain extent, and the drying speed of the tissue surface is accelerated, so that the composite tissue adhesive has more than 500% of liquid absorption, preferably 600% -1500%.

On the other hand, the composite tissue adhesive has two groups which can be bonded with amino groups on wound tissues, so that the adhesive strength of the adhesive and the wound is improved to a great extent, the tissue adhesive strength of over 180kPa can be achieved, and meanwhile, the composite tissue adhesive has mechanical strength of over 50N.

The composite tissue adhesive is a dry tissue adhesive, does not need low-temperature storage, is convenient to store and transport, has higher liquid absorbability and super-strong adhesive property, can be directly used on a moist wound surface, is degradable, does not release heat during gelling, can achieve a good moist wound surface adhesive effect, and meets clinical requirements.

According to the preparation method of the composite tissue adhesive, the composite three-dimensional porous matrix of methacrylic anhydrized gelatin and polyacrylic acid-NHS is obtained, and dopamine is adsorbed on the surface, so that the defects of low grafting rate and low content of modified polydopamine in a common chemical grafting method can be overcome, and the surface of the composite tissue adhesive has more dopamine and further has higher tissue adhesion strength.

On the other hand, the composite tissue adhesive obtained by the preparation method of the invention has polydopamine and succinimide end groups simultaneously, and can form bonding with amino groups on wound tissues, so that the adhesive is bonded with the wound, the tissue adhesion strength of the adhesive can be well increased, and polylysine and/or polyethyleneimine can be added in the preparation process to further enhance the wet mechanical strength of the composite tissue adhesive.

Detailed Description

The present invention will be further described with reference to specific embodiments, but the present invention is not limited to the examples in any way. The starting reagents employed in the examples of the present invention are, unless otherwise specified, those that are conventionally purchased.

Example 1

A composite tissue adhesive comprises a three-dimensional porous matrix and an enhanced adhesion factor adsorbed on the surface of the matrix, wherein the three-dimensional porous matrix is obtained by freeze-drying a composite hydrogel of methacrylic acid anhydridized gelatin and polyacrylic acid grafted with N-hydroxysuccinimide, the enhanced adhesion factor is polydopamine,

the composite tissue adhesive also comprises polylysine and polyethyleneimine, wherein carboxyl groups of the polylysine and the polyethyleneimine are connected with the terminal group of the polyacrylic acid grafted succinimide through peptide bonds.

The preparation method of the composite tissue adhesive comprises the following steps:

s1: methacrylic anhydrified gelatin (substitution of methacrylic acid 75%) and polyacrylic acid were mixed and the polyacrylic acid was NHS grafted: weighing 20mL of water in a beaker, adding 2g of polyacrylic acid, 0.5g of EDC, 0.1g of NHS and 0.02g of methacrylic anhydrized gelatin in sequence, stirring and dissolving uniformly, wherein the mass ratio of the methacrylic anhydrized gelatin to the polyacrylic acid is 1: 100, respectively;

s2: adding 0.05g of alpha-ketoglutaric acid, uniformly stirring, transferring a proper amount of solution to an oxygen-free forming mold (the thickness is not more than 1.5mm), carrying out photo-crosslinking on the mixture grafted in the S1, and irradiating by using a 284nm and 10W ultraviolet lamp for 30-120min until the mixture is completely cured into a hydrogel form, wherein the addition amount of a photo-crosslinking agent is 1.9% (W/W);

s3: placing the hydrogel in the S2 in a refrigerator at-80 ℃ for freezing overnight, then transferring to a freeze dryer for primary low-temperature freeze drying to prepare a three-dimensional porous matrix;

s4: soaking 2.0g of the three-dimensional porous matrix sample in S3 in a solution containing 0.6g/mL of dopamine and adjusted to pH8.5 by using polylysine and polyethyleneimine, continuously introducing oxygen into the solution, and taking out after soaking for 24h to obtain a composite adhesive precursor;

s5: and (4) performing second low-temperature freezing on the composite adhesive precursor soaked in the S4, performing second freeze-drying, hermetically packaging the tissue adhesive, and performing irradiation sterilization to obtain the composite tissue adhesive.

Example 2

the composite tissue adhesive also comprises polylysine, and the carboxyl of the polylysine is connected with the terminal group of the polyacrylic acid grafted succinimide through peptide bonds.

s1: methacrylic anhydrified gelatin (95% substitution of methacrylic acid) and polyacrylic acid were mixed and the polyacrylic acid was NHS grafted: weighing 20mL of water in a beaker, adding 5g of polyacrylic acid, 0.5g of EDC2g, 0.5g of NHS and 0.1g of methacrylic anhydrized gelatin in sequence, stirring and dissolving uniformly, wherein the mass ratio of the methacrylic anhydrized gelatin to the polyacrylic acid is 1: 50;

s2: adding 0.2g I2959 ultraviolet initiator, stirring uniformly, transferring a proper amount of solution to an oxygen-free forming mold (the thickness is not more than 1.5mm), carrying out photo-crosslinking on the grafted mixture in S1, and irradiating for 30-120min by using a 284nm and 10W ultraviolet lamp until the mixture is completely cured into hydrogel, wherein the addition amount of the photo-crosslinked crosslinking agent is 2.6% (W/W);

s4: 3.0g of the three-dimensional porous matrix sample in the S3 is soaked in a polylysine-PBS 30ml solution with the pH value of 8.5 and containing 0.2g of dopamine, oxygen is continuously introduced into the solution, and the sample is taken out after being soaked for 24 hours to obtain a composite adhesive precursor;

Example 3

the composite tissue adhesive also comprises polyethyleneimine, wherein carboxyl groups of the polyethyleneimine are connected with the terminal groups of the polyacrylic acid grafted succinimide through peptide bonds.

s1: methacrylic anhydrified gelatin (substitution of methacrylic acid 85%) and polyacrylic acid were mixed and the polyacrylic acid was NHS grafted: weighing 20mL of water in a beaker, adding 3g of polyacrylic acid, 1g of EDC1g, 0.2g of NHS and 0.06g of methacrylic anhydrized gelatin in sequence, stirring and dissolving uniformly, wherein the mass ratio of the methacrylic anhydrized gelatin to the polyacrylic acid is 1: 50;

s2: adding 0.13g of LAP blue light initiator, uniformly stirring, transferring a proper amount of solution to an oxygen-free forming mold (the thickness is not more than 1.5mm), carrying out photo-crosslinking on the grafted mixture in S1, and irradiating for 30-120min by using a 405nm and 10W ultraviolet lamp until the mixture is completely cured into hydrogel, wherein the addition amount of the photo-crosslinked crosslinking agent is 3.1% (W/W);

s4: 3.0g of the three-dimensional porous matrix sample in the S3 is soaked in 35mL of polyethyleneimine-PBS (phosphate buffered saline) containing 0.4g of dopamine and having the pH value of 8.5, oxygen is continuously introduced into the solution, and the solution is taken out after being soaked for 24 hours to obtain a composite adhesive precursor;

Example 4

The composite tissue adhesive comprises a three-dimensional porous matrix and adhesion-enhancing factors adsorbed on the surface of the matrix, wherein the three-dimensional porous matrix is obtained by freeze-drying a composite hydrogel of methacrylic acid anhydridized gelatin and polyacrylic acid grafted with N-hydroxysuccinimide, and the adhesion-enhancing factors are polydopamine.

s1: methacrylic anhydrified gelatin (95% substitution of methacrylic acid) and polyacrylic acid were mixed and the polyacrylic acid was NHS grafted: weighing 20mL of water in a beaker, adding 2g of polyacrylic acid, 0.5g of EDC, 0.1g of NHS and 0.02g of methacrylic anhydrized gelatin in sequence, stirring and dissolving uniformly, wherein the mass ratio of the methacrylic anhydrized gelatin to the polyacrylic acid is 1: 100, respectively;

s4: soaking 2.0g of the three-dimensional porous matrix sample in S3 in 10mL of PBS (phosphate buffer solution) containing 0.3g of dopamine and having pH of 8.5, continuously introducing oxygen into the solution, and taking out after soaking for 24h to obtain a composite adhesive precursor;

Comparative example 1

A composite tissue adhesive is prepared by the following steps:

s1: methacrylic anhydrified gelatin (substitution rate of methacrylic acid 75%) and polyacrylic acid body were mixed: weighing 20mL of water in a beaker, adding 2g of polyacrylic acid and 0.02g of methacrylic acid gelatin in sequence, stirring and dissolving uniformly, wherein the mass ratio of the methacrylic acid anhydrified gelatin to the polyacrylic acid is 1: 100, respectively;

s2: adding 0.05g of alpha-ketoglutaric acid, uniformly stirring, transferring a proper amount of solution to an oxygen-free forming mold (the thickness is not more than 1.5mm), carrying out photo-crosslinking on the mixture grafted in S1, and irradiating for 30-120min by using an 284nm and 10W ultraviolet lamp until the mixture is completely cured into a hydrogel;

s4: soaking 2g of the three-dimensional porous matrix sample in S3 in a solution containing 0.6g of dopamine and containing polylysine and polyethyleneimine with the pH value of 8.5, continuously introducing oxygen into the solution, and taking out after soaking for 24h to obtain a composite adhesive precursor;

Comparative example 2

A composite tissue adhesive is prepared by the following steps:

s1: methacrylic anhydrified gelatin (substitution of methacrylic acid 85%) and polyacrylic acid were mixed and the polyacrylic acid was NHS grafted: weighing 20mL of water in a beaker, adding 2g of polyacrylic acid, 0.5g of EDC, 0.1g of NHS and 0.02g of methacrylic acid gelatin in sequence, stirring and dissolving uniformly, wherein the mass ratio of methacrylic acid anhydrified gelatin to polyacrylic acid is 1: 100, respectively;

s2: adding 0.05g of alpha-ketoglutaric acid, uniformly stirring, transferring a proper amount of solution to an oxygen-free forming mold (the thickness is not more than 1.5mm), carrying out photo-crosslinking on the mixture grafted in the S1, and irradiating for 30-120min by using an 284nm and 10W ultraviolet lamp until the mixture is completely cured into hydrogel, thereby obtaining the composite tissue adhesive.

Result detection

(1) Detection of polydopamine content

Step 1: 1g of the composite tissue adhesive is put into a 50mL centrifuge tube, purified water is added to completely immerse the composite tissue adhesive, and a cover is covered for sealing.

Step 2: the tube was placed on a shaker and shaken at high speed for 20 minutes.

And step 3: putting the solution into a clean beaker A, keeping the composite tissue adhesive in a centrifuge tube,

and 4, step 4: purified water was added to the centrifuge tube to completely submerge the composite tissue adhesive. And (5) repeating the step 2 to the step 3. The solution was poured on into beaker a.

And 5: repeating steps 2-4 until no black particles are visible in the solution.

Step 6: and putting the solution in the beaker A into a low-temperature refrigerator to solidify the solution. The samples were lyophilized using a lyophilizer. A dry sample was obtained.

And 7: the resulting dried sample was weighed.

The results are shown in Table 1.

TABLE 1

(2) NHS grafting Rate detection

The detection method is to measure the NHS concentration by an ultraviolet-visible spectrophotometry.

Standard curve:

n-hydroxysuccinimide (NHS) 12.5mg to 100mL volumetric flask was weighed, dissolved and diluted to the mark with PBS buffer solution of pH7.4 as control stock solution. 0.4mL, 0.8mL, 1.2mL, 1.6mL and 2.0mL of the buffer solution were transferred into 5 10mL volumetric flasks, and PBS buffer solution was added to dilute the solution to a constant volume. Solutions were obtained at concentrations of 0.5mg/mL, 1.0mg/mL, 1.5mg/mL, 2.0mg/mL, 2.5 mg/mL. According to the ultraviolet-visible spectrophotometry 0401 in the general rule of the four departments of the 2020 edition of Chinese pharmacopoeia, an ultraviolet spectrophotometer is used for detecting the absorbance value at the maximum absorption wavelength of 260 nm. Meanwhile, PBS buffer solution is used as a blank test, parallel detection is carried out twice, and an average value is taken. The NHS concentration was plotted on the abscissa and the absorbance on the ordinate to prepare a standard curve.

Preparing a test solution:

weighing about 1g of the composite tissue adhesive, placing the composite tissue adhesive in a clean mortar, grinding the composite tissue adhesive until no obvious blocks exist, transferring the composite tissue adhesive into a centrifuge tube, adding 25ml of PBS (phosphate buffered saline) buffer solution with the pH value of 7.4 into the centrifuge tube, and sealing the opening of the centrifuge tube. The tube was placed on a shaker for 2 minutes and then leached for 5 hours at 37 ℃. + -. 1 ℃. The solution in the centrifuge tube was filtered. The filtrate was taken, and diluted 100-fold with PBS buffer solution as a test solution.

And (3) calculating a detection result:

taking the test solution, and detecting the absorbance value of the test solution at the maximum absorption wavelength of 260nm by using an ultraviolet spectrophotometer according to 0401 ultraviolet-visible spectrophotometry in the four ministry of the 2020 edition of Chinese pharmacopoeia. The NHS content was calculated.

m(NHS)＝100*C*V，

Wherein:

m (NHS) is the content of NHS, mg;

c is the mass concentration of NHS found by a standard curve, mg/mL;

v is the volume of filtrate, mL, after dilution 100 with PBS buffer.

Then the grafting rate of NHS is m (NHS)/m (polyacrylic acid or acrylic acid monomer) 10-3%

The results are shown in Table 2.

TABLE 2

Examples	m(NHS)/mg	m (polyacrylic acid or acrylic acid monomer)/g	Graft ratio
				Example 1	85	2	4.25％
Example 2	385	5	7.7％
				Example 3	155	3	5.17％
Example 4	80	2	4.0％

(3) Evaluation of liquid absorbency

The composite tissue adhesives of the above examples and comparative examples were taken, weighed as M0, completely immersed in PBS solution and timed, and after 5min of immersion, excess water on the hydrogel surface was removed by wiping and weighed as M1.

The liquid absorption rate was calculated as follows:

liquid absorption rate (M1-M0)/M0%

The results are shown in Table 3.

TABLE 3

Examples	Liquid absorption rate
		Example 1	670％
Example 2	1205％
		Example 3	838％
Example 4	1156％
		Comparative example 1	650％
Comparative example 2	132％

(4) Mechanical testing and adhesion Strength evaluation

The three-dimensional porous matrix obtained by the first freeze-drying and the composite tissue adhesive obtained by the second freeze-drying in the above examples and comparative examples were respectively subjected to mechanical testing and adhesion strength evaluation. The detection method comprises the following steps:

and (3) mechanical testing: the sample was moistened with physiological saline to form a hydrogel, and the hydrogel was cut into 1cm by 4cm strips. The sample strips were clamped separately on a universal tensile machine, which was started and the maximum force at which the gel was pulled off was recorded.

Adhesion strength test: the three-dimensional porous matrices obtained by the first lyophilization and the second lyophilization in the above examples and comparative examples were taken, respectively, and adhesion tests were performed on the wet pigskin and pork liver. Before the test, the pigskin is respectively soaked in water for 30min, and after being taken out, the composite tissue adhesive is respectively attached to the wet pigskin and pressed for 5 min. The adhesion effect was observed and a tear resistance test was performed using a tensile machine to test the maximum force required to pull the composite tissue adhesive apart.

The detection results are shown in Table 4

TABLE 4

According to the data, the tissue adhesion strength of the composite tissue adhesive containing the porous structure and adsorbed polydopamine is greater than that of a three-dimensional porous matrix formed by composite freeze-drying of methacrylic acid anhydridized gelatin and grafted NH S polyacrylic acid, and the wet wound surface can be firmly blocked; and the polylysine and/or polyethyleneimine are/is compounded in the embodiments 1-3, so that the mechanical property of the obtained composite tissue adhesive is further enhanced.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The composite tissue adhesive is characterized by comprising a three-dimensional porous matrix and an adhesion-enhancing factor adsorbed on the surface of the matrix, wherein the three-dimensional porous matrix is obtained by freeze-drying a composite hydrogel of methacrylic anhydridized gelatin and polyacrylic acid grafted with N-hydroxysuccinimide, and the adhesion-enhancing factor is polydopamine.

2. The complex tissue adhesive of claim 1, further comprising polylysine and/or polyethyleneimine, wherein carboxyl groups of the polylysine and/or polyethyleneimine are linked to succinimide terminal groups of the N-hydroxysuccinimide grafted polyacrylic acid by peptide bonds.

3. The composite tissue adhesive according to claim 1 or 2, wherein the polydopamine loading of the composite tissue adhesive is 10% (w/w) to 30% (w/w), and the grafting ratio of the N-hydroxysuccinimide-grafted polyacrylic acid is 1% to 10%.

4. The composite tissue adhesive according to claim 1 or 2, wherein the liquid absorption amount of the composite tissue adhesive is 500% or more, the wet mechanical strength is 50N or more, and the tissue adhesion strength is 180kPa or more.

5. A preparation method of a composite tissue adhesive is characterized by comprising the following steps:

6. The method for producing a composite tissue adhesive according to claim 5, wherein the substitution rate of methacrylic acid in the methacrylic anhydrified gelatin in S1 is not less than 40%.

7. The method for preparing a composite tissue adhesive according to claim 5, wherein the grafting ratio of polyacrylic acid grafted with N-hydroxysuccinimide in S1 is 1% to 10%.

8. The method for preparing a composite tissue adhesive according to claim 5, wherein the mass ratio of the methacrylic anhydrified gelatin to the polyacrylic acid or the acrylic acid in S1 is 1: (1-100).

9. The method of claim 5, wherein the dopamine in S4 solution has a concentration of 0.5g/mL to 6 g/mL.

10. The method for preparing a composite tissue adhesive according to claim 5, wherein the solvent in the dopamine solution of S4 is one of a PBS buffer solution, a PBS buffer solution containing polylysine, a PBS buffer solution containing polyethyleneimine, and a mixed solution of polyethyleneimine and polylysine.

11. Use of a composite tissue adhesive according to any one of claims 1 to 10 in the preparation of a moist wound adhesive product.