A nano-composite hydrogel dressing with reversible adhesion-photothermal sterilization function and a preparation method thereof

Abstract

The application discloses a kind of nano composite hydrogel dressings with reversible adhesion-photothermal sterilization function and preparation method thereof.The preparation method includes the following:1) preparation of metal organic framework ZIF-8, which is immersed in a solution containing cyanidin CY-7 to achieve drug adsorption;DA is then used to coat the surface of the obtained sample to obtain ZIF-8 / CY-7 / PDA particles;2) preparation of 7-carboxymethoxyl-4-methyl coumarin CM with carboxyl at the end;3) through EDC coupling reaction, CM is grafted onto the side chain of dopamine-modified chitosan molecules to obtain CS-DA-CM;4) disperse ZIF-8 / CY-7 / PDA particles and angiogenic components in CS-DA-CM solution to obtain the dressing.The dressing can be injected and used, and can be gelled in situ to achieve adhesion when irradiated with a light source with a wavelength greater than 300 nm, and can be converted back to a solution when irradiated with a light source with a wavelength less than 280 nm;when an infrared wavelength with a wavelength of 820 nm is used, photothermal effect can be excited to achieve photothermal sterilization at the wound site, and photothermal effect can promote blood flow to accelerate wound healing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydrogel dressing preparation, in particular to a kind of nano composite hydrogel dressing with reversible adhesion-photothermal sterilization function and preparation method thereof. BACKGROUND

[0002] Skin, as the largest tissue of human body, bears the responsibility of the first barrier of human body. However, skin is easily damaged by external factors, leading to wounds, such as burns, scalds, mechanical damage, etc. And after the skin is damaged, it is easy to cause infection, excessive inflammation and other symptoms, which will greatly slow down the healing rate of the skin, and in severe cases, it can even lead to skin ulceration, amputation, etc., causing great pain to the patient and increasing the patient's economic and psychological burden.

[0003] Dressing, as a physical barrier material, can temporarily isolate the wound from the outside world, reducing the risk of wound infection; At the same time, it can load related active drugs to promote wound healing, so it is widely used. Among them, hydrogel dressing, with its extracellular matrix structure, high moisture retention, good biocompatibility and other advantages, gradually stands out in this field. However, the existing hydrogel dressing cannot match the shape of the wound, cannot achieve adhesion to the wound, and cannot be easily peeled off and replaced after use, which greatly limits its application. At the same time, pure hydrogel dressing often does not have biological activity, and cannot contribute to the prevention and treatment of infection, the promotion of blood circulation at the wound site, and the improvement of wound healing efficiency.

[0004] Therefore, the present application designs a kind of nano composite hydrogel dressing with reversible adhesion-photothermal sterilization function and preparation method thereof, which can shape the hydrogel according to the shape of the wound, achieve reversible adhesion to the wound, and load ZIF-8 / CY-7 / PDA particles with photothermal effect and angiogenic active components in the hydrogel, inhibit infection and achieve rapid wound repair. SUMMARY

[0005] The purpose of the present application is to solve the practical application problems of the existing hydrogel dressing, which cannot match the shape of the wound, cannot achieve adhesion to the wound, cannot be easily peeled off and replaced after use, and does not have biological activity. A kind of nano composite hydrogel dressing with reversible adhesion-photothermal sterilization function and preparation method thereof is provided.

[0006] The specific preparation steps of the hydrogel dressing according to the present application include the following:

[0007] 1) ZIF-8 nanoparticles were prepared using an ultrasonic aqueous synthesis method and loaded with anthocyanin CY-7 via an immersion adsorption method. The CY-7-loaded ZIF-8 nanoparticles were then immersed in a Tris-HCl (pH 8.5) solution containing dopamine (DA) to form a PDA coating on the nanoparticle surface via in situ self-polymerization. The resulting ZIF-8 / CY-7 / PDA particles were then centrifuged at high speed.

[0008] 2) Using a trace amount of potassium iodide as a catalyst, a solution of 7-hydroxy-4-methylcoumarin, bromoacetic acid, and potassium carbonate in ethanol was heated under reflux for 15-25 hours, then the solution was cooled to room temperature, acidified, and the product was extracted with ether and water; after separation, the aqueous phase was removed, and the water in the organic phase was absorbed by magnesium sulfate, and the solvent was removed by rotary evaporation to obtain the desired product, 7-carboxymethoxy-4-methylcoumarin (CM);

[0009] 3) Dissolve 7-carboxymethoxy-4-methylcoumarin and dopamine-grafted chitosan (CS-DA) in a DMSO / deionized water mixture at 50°C in a water bath. Add EDC and NHS for a coupling reaction to graft 7-carboxymethoxy-4-methylcoumarin onto the amino groups of the CS-DA side chains. Finally, dialyze using a regenerated cellulose dialysis bag and freeze-dry to obtain the desired molecule, CS-DA-CM.

[0010] 4) In a dark place and at 50°C water bath, CS-DA-CM was dissolved in PBS solution, and ZIF-8 / CY-7 / PDA particles and vasculogenic active components were added. After Vortex mixing, the mixture was sterilized by irradiation to obtain a nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function.

[0011] The hydrogel dressing of the present invention is injectable and can adapt to wounds of any shape. It also has reversible adhesion and photothermal sterilization functions. Specifically, the hydrogel dressing is injected into the patient's wound using a syringe. The fluidity of the solution allows the dressing to conform to the shape of the wound. It is then irradiated with a light source with a wavelength greater than 300nm for in-situ photocuring while achieving adhesion between the gel and the wound tissue. An infrared light source with a wavelength of 850nm is then used to stimulate the photothermal effect of the ZIF-8 / CY-7 / PDA particles within the gel matrix, achieving photothermal sterilization. At the same time, the thermal effect can promote blood flow around the wound and promote wound healing. After the dressing has been used for a certain period of time, UV light with a wavelength less than 280nm is used to transform the gel into a solution, achieving the purpose of de-adhesion and facilitating dressing replacement.

[0012] In the technical scheme, further, the process for preparing ZIF-8 in step 1) is as follows: equal volume of Zn(NO3)2 aqueous solution is added dropwise into 2-methylimidazole aqueous solution to form a mixed solution, the mixed solution is placed into an ultrasonic device for oscillation reaction, the solution after reaction is centrifuged at high speed, the supernatant is discarded, the ZIF-8 particles are obtained after being washed with methanol and re-centrifuged at least twice, and then air-dried and ground. Preferably, the concentration of Zn(NO3)2·6H2O is 0.03-0.09 mol / L, and the concentration of 2-methylimidazole is 0.1-0.5 mol / L; the ultrasonic conditions are as follows: 30-80 kHz, 60-150 W ultrasonic device, ultrasonic for 8-20 min; the high-speed centrifugation conditions are as follows: 6000-12000 rpm, centrifugation time of 10-20 min. The impregnation adsorption method is as follows: under light shielding conditions, ZIF-8 nanoparticles are immersed in CY-7 aqueous solution, the concentration of ZIF-8 is 0.0125 g / ml, the concentration of CY-7 solution is 50-100 μmol / L, the adsorption time is 12-48 h, and after adsorption, centrifugation is performed, preferably, the centrifugation conditions are as follows: 8000-10000 rpm high-speed centrifugation at room temperature, and the centrifugation time is 8-15 min. In the in-situ self-polymerization, the concentration of DA in the solution is 6-12 mg / ml, and the concentration of CY-7 loaded ZIF-8 nanoparticles is 50-100 mg / ml, preferably, stirring is performed during the in-situ self-polymerization, the stirring rate is 800-1000 r / min, the reaction time is 4-8 h, after reaction, high-speed centrifugation is performed, the centrifugation rate is 8000-10000 rpm, and the centrifugation time is 8-15 min.

[0013] Further, in step 2), the amounts of 7-hydroxy-4-methylcoumarin, bromoacetic acid and potassium carbonate in the solution are 50-125 mM, 250-350 mM and 75-125 mM, respectively.

[0014] Further, in the grafting reaction of 7-carboxymethoxyl-4-methylcoumarin and CS-DA in step 3), the concentration of 7-carboxymethoxyl-4-methylcoumarin is 1-3 wt%, the concentration of CS-DA is 5-10 wt%, the ratio of DMSO / deionized water mixed solvent is 10 wt% DMSO / 90 wt% deionized water, the concentration of EDC is 0.025-0.06 wt%, the concentration of NHS is 0.04-0.08 wt%, the coupling reaction time is 12-48 hours, and the magnetic stirring rate in the reaction is 200-500 r / min; the dialysis is deionized water dialysis for 5-7 days under light shielding.

[0015] Further, the concentration of the CS-DA-CM in the step 4) is 5-20 wt%; the amount of the ZIF-8 / CY-7 / PDA particles is 5-20 mg / ml; and the pro-angiogenic component is one or more of a-FGF, b-FGF, PD-ECGF, TGF, TNF and VEGF, and the concentration of the pro-angiogenic component is 10-50 μg / ml.

[0016] Compared with the prior art, the present application has the following advantages:

[0017] 1) The present application uses bromoacetic acid, 7-hydroxy-4-methyldopamine, dopamine grafted chitosan, ZIF-8, CY-7, DA, etc. as raw materials, and a nano-composite hydrogel dressing with reversible adhesion-photothermal sterilization function is prepared by a combination process of ultrasonic aqueous synthesis, immersion adsorption, in-situ self-polymerization, chemical medium and in-situ photocuring, and the excellent performance of the dressing is successfully achieved through the above raw materials and combination process.

[0018] 2) The CS-DA-CM in the present application is synthesized for the first time, and bromination reaction and EDC coupling reaction are used, and dopamine chain segments and coumarin structures are simultaneously used on the molecule. Dopamine can achieve wet adhesion, and two coumarin structures can generate ring-opening reaction and ring-opening reaction under the action of a specific wavelength light source. In practice, the molecule can be in-situ gelled under the irradiation of a wavelength greater than 300 nm, and can be converted from a gel to a solution under the irradiation of a wavelength less than 280 nm. The hydrogel dressing substrate can adapt to different wound shapes; the grafted dopamine can adhere to prevent the hydrogel dressing from detaching or falling off the wound, and can be converted into a solution when the dressing needs to be replaced (irradiation of a wavelength less than 280 nm) to prevent secondary damage to the wound due to the adhesion of the dressing, which has great practicality and operability; and the macromolecular backbone of the hydrogel raw material is chitosan, which has good biocompatibility and safety; and the hydrogel can also adsorb the exudate of the surrounding tissue of the wound.

[0019] 3) The ZIF-8 / CY-7 / PDA particles in the application are synthesized for the first time. CY-7 has high near-infrared (NIR) absorption coefficient, easy functional modification of molecular structure, high photo-thermal conversion efficiency and low cytotoxicity, and has played a big role in the research of photo-thermal therapy in recent years, but CY-7 molecules always face the problem of easy photobleaching, which limits its clinical application; ZIF-8, as a kind of nanoparticle with high specific surface area, can realize effective adsorption and efficient loading of CY-7, and after CY-7 is loaded in ZIF-8, the anti-photobleaching performance is greatly improved, and the stability of photo-thermal switch is significantly enhanced. In addition, ZIF-8 / CY-7 has good dispersibility, which expands the feasibility of preparing uniform and controllable photo-thermal materials; and the introduction of PDA coating further stabilizes the long-term loading of CY-7 in ZIF-8 and prolongs the release period of CY-7.

[0020] 4) The nano-composite hydrogel dressing with reversible adhesion-photothermal sterilization function in the application has a triple composite structure, from outside to inside, hydrogel matrix, PDA coating and metal organic framework. When the hydrogel is actually used, in-situ gelation at the wound site can be realized by using a syringe, and the shape of the wound can be matched. At the same time, a light source with a wavelength greater than 300 nm is used to realize the adhesion of the hydrogel and the wound tissue. Further, a light source with a wavelength of 820 nm can be used regularly to excite the photo-thermal effect of CY-7, kill bacteria at the wound site, promote blood flow at the wound site, and promote wound healing. Moreover, the vascularization factor directly loaded in the hydrogel is continuously and slowly released from the inside of the hydrogel, which plays a role in promoting vascularization, and together improves the rate and effect of wound healing. When the use cycle of the hydrogel dressing ends, the adhesion can be eliminated by irradiation with a light source with a wavelength less than 280 nm, and the dressing can be replaced.

[0021] 5) The nano-composite hydrogel dressing with reversible adhesion-photothermal sterilization function designed in the application also has the functions of ultraviolet light curing, light reversible adhesion, cyclic photo-thermal sterilization, photo-thermal promotion of blood circulation, promotion of vascularization, absorption of tissue exudate, etc., which well meet the use requirements of wound dressings. The organic synergy of the above functions shows great advantages in the prevention and treatment of wound infection and wound healing. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a schematic diagram of the reversible gelation adhesion principle of 7-carboxymethoxy-4-methyl coumarin under different wavelength light irradiation;

[0023] Figure 2 It is a TEM image of ZIF-8 / CY-7 / PDA particles;

[0024] Figure 3 It is a SEM image of the nano-composite hydrogel dressing with reversible adhesion-photothermal sterilization function.

[0025] Figure 4 Schematic diagram of reversible photothermal process of nano-composite hydrogel dressing with reversible adhesion-photothermal sterilization function. DETAILED DESCRIPTION

[0026] The technical solutions of the present application are further illustrated below in combination with specific embodiments and the accompanying drawings.

[0027] Example 1:

[0028] 1) Equal volume of Zn(NO3)2 was added dropwise into 2-methylimidazole solution, and the reaction was allowed to proceed fully; the ultrasonic aqueous phase synthesis method required that the reaction be completed in a 50 kHz, 100 W ultrasonic device for 10 min; the reaction solution finally appeared as a milky white liquid, which was centrifuged at 10,000 rpm at room temperature for 10 min, washed with methanol solution and centrifuged twice. After air drying in a fume hood, high-purity ZIF-8 particles were obtained after grinding. 1 g of ZIF-8 particles was placed in 80 mL of CY7 aqueous solution with a concentration of 60 μmol / L, and the reaction time was 12 h. After adsorption, high-speed centrifugation was performed at 8,000 rpm at room temperature, and the product was washed with pure water and centrifuged twice. After air drying in a fume hood, CY-7 loaded ZIF-8 was obtained. Further, the above CY-7 loaded ZIF-8 (50 mg / ml) was immersed in a Tris-HCl (pH = 8.5) solution containing 6 mg / ml DA, and a PDA coating layer was formed on the surface of the nanoparticles by in-situ self-polymerization reaction for 4 h. High-speed centrifugation was performed to obtain ZIF-8 / CY-7 / PDA particles;

[0029] 2) Trace amount of potassium iodide was used as catalyst, 63 mmol of 7-hydroxy-4-methyl coumarin was added into 220 ml of ethanol solution, followed by 260.7 mmol of bromoacetic acid and 108 mmol of potassium carbonate, and the solution was heated to reflux for 22 hours. Then the solution was cooled to room temperature, acidified, and the product was extracted with diethyl ether and water. After separation with a separatory funnel, the aqueous phase was removed, and the organic phase was absorbed with magnesium sulfate to remove water. The solvent was removed by rotary evaporation to obtain the desired product 7-carboxymethoxy-4-methyl coumarin (CM) with a purity of >97.6% and a yield of 64%;

[0030] 3) In a 50°C water bath, 2wt% 7-carboxylic acid methoxy-4-methyl coumarin and 10wt% CS-DA were dissolved in 10wt% DMSO / 90wt% deionized water mixed solvent, 0.03wt% EDC and 0.06wt% NHS were added for coupling reaction under the condition of 400 rpm magnetic stirring for 24 hours, and finally using 3000 molecular weight regenerated cellulose dialysis bag for dialysis for 7 days, then freeze-drying to obtain CS-DA-CM, stored in the dark, ready for use. 4) In the dark and 50°C water bath, 10wt% CS-DA-CM was dissolved in PBS solution, then 5mg / ml ZIF-8 / CY-7 / PDA particles and 10ug / ml VEGF were added, vortex mixed uniformly, and then irradiated for sterilization, ready for use;

[0031] 5) The above solution was injected into the patient's wound using a syringe, and the solution was fitted to the shape of the wound by its fluidity, and then irradiated with a light source with a wavelength greater than 300 nm for 5 min for in-situ photocuring and wet adhesion to the wound tissue.

[0032] The composite hydrogel dressing prepared under the above conditions showed that the cell survival rate was 92.4% compared with the control group without the hydrogel dressing in the 3-day MTT experiment; the adhesion strength was about 22.3kPa; after irradiation with a light source with a wavelength less than 280 nm, the dressing could change from a gel state to a solution state; and after irradiation with a light source with a wavelength of 850 nm for 10 min, the gel temperature could reach about 46.6°C, and the photothermal effect was reversible.

[0033] Example 2:

[0034] 1) Equal volume of Zn(NO3)2 was added dropwise into 2-methylimidazole solution, and the reaction was allowed to proceed; the ultrasonic aqueous phase synthesis method required 10 min of reaction in a 50 kHz, 100 W ultrasonic device; the reaction solution finally appeared as a milky white liquid, which was centrifuged at 10000 rpm at room temperature for 10 min, washed with methanol solution and centrifuged twice. Air-dried in a fume hood, and ground uniformly to obtain high-purity ZIF-8 particles. 1g of ZIF-8 particles was placed in 80mL of CY7 aqueous solution with a concentration of 60μmol / L, and the reaction time was 12h. After adsorption, high-speed centrifugation was performed at 8000rpm at room temperature, and pure water was used for washing and centrifugation twice. Air-dried in a fume hood to obtain CY-7 loaded ZIF-8. Further, the above CY-7 loaded ZIF-8 (50mg / ml) was immersed in a Tris-HCl (pH=8.5) solution containing 6mg / ml DA, and a PDA coating layer was formed on the surface of the nanoparticles by in-situ self-polymerization reaction for 4h, and high-speed centrifugation was performed to obtain ZIF-8 / CY-7 / PDA particles;

[0035] 2) 63 mmol 7-hydroxy-4-methylcoumarin and 260.7 mmol bromoacetic acid, 108 mmol potassium carbonate were added into 220 ml ethanol solution in sequence as catalyst with trace amount of potassium iodide, heated to reflux for 22 hours, then the solution was cooled to room temperature, acidified and extracted with diethyl ether and water; after separation with a separatory funnel, the aqueous phase was removed, and the organic phase was absorbed with magnesium sulfate, and the solvent was removed by rotary evaporation to obtain the desired product 7-carboxymethoxyl-4-methylcoumarin (CM), with purity > 97.6% and yield 64%;

[0036] 3) 2 wt% 7-carboxymethoxyl-4-methylcoumarin and 10 wt% CS-DA were dissolved in 10 wt% DMSO / 90 wt% deionized water mixed solvent in a 50°C water bath, 0.03 wt% EDC and 0.06 wt% NHS were added for coupling reaction under the condition of magnetic stirring at 400 rpm for 24 hours, and then the product was obtained by freeze-drying after dialysis for 7 days using a regenerated cellulose dialysis bag with a molecular weight of 3000, and stored in the dark until use.

[0037] 5) The above solution was injected into the patient's wound using a syringe, and the solution was fitted to the shape of the wound by its fluidity, and then in-situ photocured and wet-adhered to the wound tissue by irradiation with a light source with a wavelength greater than 300 nm for 5 min.

[0038] Compared with Example 1, the amount of ZIF-8 / CY-7 / PDA particles was increased in this example. The 3-day MTT test results of the composite hydrogel dressing prepared under the above conditions showed that the cell survival rate was 89.7% compared with the control group, the adhesion strength was about 20.5 kPa, the dressing could be converted from a gel state to a solution state after irradiation with a light source with a wavelength less than 280 nm, and the gel temperature could reach about 53.1°C after irradiation with a light source with a wavelength of 850 nm for 10 min, and the photothermal effect was reversible, as shown in Figure 4 .

[0039] Example 3:

[0040] 1) Equal volume of Zn(NO3)2 was added dropwise into 2-methylimidazole solution, and the reaction was allowed to proceed; the ultrasonic aqueous phase synthesis method required that the reaction be completed in an ultrasonic device at 50 kHz, 100 W for 10 min; the reaction solution finally appeared as a milky white liquid, which was centrifuged at 10,000 rpm at room temperature for 10 min, washed with methanol solution twice by centrifugation. Air-dried in a fume hood, and ground uniformly to obtain high-purity ZIF-8 particles. 1 g of ZIF-8 particles was placed in 80 mL of CY7 aqueous solution with a concentration of 60 μmol / L, and the reaction time was 12 h. After adsorption, high-speed centrifugation was performed at 8,000 rpm at room temperature, and the solution was washed with pure water twice by centrifugation. Air-dried in a fume hood to obtain CY-7 loaded ZIF-8. Further, the above CY-7 loaded ZIF-8 (50 mg / ml) was immersed in a Tris-HCl (pH = 8.5) solution containing 6 mg / ml DA, and a PDA coating layer was formed on the surface of the nanoparticles by in-situ self-polymerization reaction for 4 h. High-speed centrifugation was performed to obtain ZIF-8 / CY-7 / PDA particles;

[0041] 2) Trace amount of potassium iodide was used as catalyst, 63 mmol 7-hydroxy-4-methyl coumarin was added into 260.7 mmol bromoacetic acid, 108 mmol potassium carbonate in 220 ml ethanol solution, heated to reflux for 22 hours, then the solution was cooled to room temperature, acidified, and then extracted with ether and water; after separation with a separatory funnel, the aqueous phase was removed, and the organic phase was absorbed with magnesium sulfate, and the solvent was removed by rotary evaporation to obtain the desired product 7-carboxymethoxy-4-methyl coumarin (CM), the product purity > 97.6%, yield 64%;

[0042] 3) 2wt% 7-carboxymethoxy-4-methyl coumarin and 10wt% CS-DA were dissolved in 10wt% DMSO / 90wt% deionized water mixed solvent in a 50°C water bath, 0.03wt% EDC and 0.06wt% NHS were added under the condition of 400 rpm magnetic stirring, and the coupling reaction was carried out for 24 hours, and then the product was dialyzed in a 3000 molecular weight regenerated cellulose dialysis bag for 7 days, and then freeze-dried to obtain CS-DA-CM, which was stored in the dark. 4) 15wt% CS-DA-CM was dissolved in PBS solution under the condition of light shielding and 50°C water bath, and then 5mg / ml ZIF-8 / CY-7 / PDA particles and 10ug / ml VEGF were added, and the mixture was vortexed and mixed uniformly, and then sterilized by irradiation, and then stored for use;

[0043] 5) The above solution was injected into the patient's wound using a syringe, and the solution was allowed to flow to conform to the shape of the wound, and then a light source with a wavelength greater than 300 nm was used to irradiate for 5 min for in-situ photocuring and wet adhesion to the wound tissue.

[0044] The composite hydrogel dressing prepared under the above conditions has a 3-day MTT test result showing that the cell survival rate is 93.1% compared with a control group; the adhesion strength is about 27.9 kPa, the dressing can be converted from a gel state to a solution state after irradiation of a light source with a wavelength of less than 280 nm; and the gel temperature can reach about 44.8°C after irradiation of a light source with a wavelength of 850 nm for 10 min, and the photothermal effect is reversible.

[0045] Example 4:

[0046] 1) Equal volume of Zn(NO3)2 was added dropwise into 2-methylimidazole solution, and the reaction was allowed to proceed fully; the ultrasonic aqueous phase synthesis method required that the reaction be completed in a 50 kHz, 100 W ultrasonic device for 10 min; the reaction solution finally appeared as a milky white liquid, which was centrifuged at 10,000 rpm at room temperature for 10 min, washed with methanol solution and centrifuged twice. After air drying in a fume hood and grinding, high-purity ZIF-8 particles were obtained. 1 g of ZIF-8 particles was placed in 80 mL of CY7 aqueous solution with a concentration of 60 μmol / L, and the reaction time was 12 h. After adsorption, high-speed centrifugation was performed at 8,000 rpm at room temperature, and the product was washed with pure water and centrifuged twice. After air drying in a fume hood, CY-7 loaded ZIF-8 was obtained. Further, the CY-7 loaded ZIF-8 (50 mg / ml) was immersed in a Tris-HCl (pH = 8.5) solution containing 6 mg / ml of DA, and a PDA coating layer was formed on the surface of the nanoparticles by in-situ self-polymerization for 4 h. High-speed centrifugation was performed to obtain ZIF-8 / CY-7 / PDA particles;

[0047] 2) Trace amount of potassium iodide was used as a catalyst, 63 mmol of 7-hydroxy-4-methylcoumarin, 260.7 mmol of bromoacetic acid, and 108 mmol of potassium carbonate were sequentially added to 220 ml of ethanol solution, heated to reflux for 22 hours, and then the solution was cooled to room temperature. After acidification, the product was extracted with diethyl ether and water; after separation with a separatory funnel, the water phase was removed, and the organic phase was absorbed with magnesium sulfate to remove water. The solvent was removed by rotary evaporation to obtain the desired product 7-carboxymethoxy-4-methylcoumarin (CM), with a purity of >97.6% and a yield of 64%;

[0048] 3) 3wt% 7-carboxymethoxy-4-methylcoumarin and 10wt% CS-DA were dissolved in 10wt% DMSO / 90wt% deionized water mixed solvent in a 50°C water bath, 0.03wt% EDC and 0.06wt% NHS were added to carry out the coupling reaction for 24 hours under the condition of magnetic stirring at 400 revolutions per minute, and finally freeze-dried after dialysis for 7 days using a regenerated cellulose dialysis bag with a molecular weight of 3000 to obtain CS-DA-CM, which was stored in the dark and used as needed. 4) 10wt% CS-DA-CM was dissolved in PBS solution under the conditions of light shielding and 50°C water bath, and then 5mg / ml ZIF-8 / CY-7 / PDA particles and 10ug / ml VEGF were added, vortexed uniformly, and then sterilized by irradiation for use;

[0049] 5) The above solution was injected into the patient's wound using a syringe, the solution was matched to the shape of the wound through its fluidity, and then in-situ photocuring and wet adhesion to the wound tissue were achieved by irradiating a light source with a wavelength greater than 300nm for 5min.

[0050] 6) Compared with Example 1, the amount of 7-carboxymethoxy-4-methylcoumarin used to modify CS-DA was increased, and the strength of the composite hydrogel dressing prepared under the above conditions was increased by 6.8% compared with the hydrogel in Example 1. The 3-day MTT experiment results of the hydrogel showed that the cell survival rate was 91.0% compared with the control group; the adhesion strength was about 21.9kPa, the dressing could be converted from a gel state to a solution state after irradiation with a light source with a wavelength less than 280nm; and the gel temperature could reach about 45.7°C after irradiation with an 850nm wavelength light source for 10min, and the photothermal effect was reversible.

Claims

1. A method for preparing a nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization functions, characterized in that: The preparation method comprises the following steps: 1) ZIF-8 nanoparticles were prepared using an ultrasonic aqueous synthesis method and loaded with anthocyanin CY-7 via an impregnation adsorption method. The CY-7-loaded ZIF-8 nanoparticles were then immersed in a Tris-HCl solution containing dopamine (DA), where a PDA coating was formed on the surface of the nanoparticles via in situ self-polymerization. ZIF-8 / CY-7 / PDA particles were then obtained by high-speed centrifugation. 2) Using a trace amount of potassium iodide as a catalyst, 7-hydroxy-4-methylcoumarin, bromoacetic acid, and potassium carbonate in ethanol were heated under reflux for 15-25 hours. The solution was then cooled to room temperature, acidified, and the product was extracted with ether and water. After separation, the aqueous phase was removed, and the water in the organic phase was absorbed by magnesium sulfate. The solvent was then removed by rotary evaporation to obtain the desired product, 7-carboxymethoxy-4-methylcoumarin CM. 3) Dissolve 7-carboxymethoxy-4-methylcoumarin (CM) and dopamine-modified chitosan molecule CS-DA in a DMSO / deionized water mixture in a 50°C water bath. Add EDC and NHS for coupling reaction to graft 7-carboxymethoxy-4-methylcoumarin onto the amino group of the CS-DA side chain. Finally, dialyze using a regenerated cellulose dialysis bag and freeze-dry to obtain CS-DA-CM. 4) In a dark place and at 50°C water bath, CS-DA-CM was dissolved in PBS solution, and ZIF-8 / CY-7 / PDA particles and vasculogenic components were added. The mixture was vortex-mixed and then sterilized by irradiation to obtain a nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function.

2. The method for preparing the nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function according to claim 1, characterized in that: In step 1): The ultrasonic aqueous synthesis method is specifically as follows: an equal volume of Zn(NO3)2 aqueous solution is added dropwise to a 2-methylimidazole aqueous solution to form a mixed solution, the mixed solution is placed in an ultrasonic device for oscillation reaction, the solution after the reaction is completed is subjected to high-speed centrifugation, the supernatant is discarded, the solution is washed with methanol and centrifuged again at least twice, and the ZIF-8 particles are obtained after air drying and grinding; The immersion adsorption method is specifically as follows: in the dark, the ZIF-8 nanoparticles are immersed in a CY-7 aqueous solution, the ZIF-8 concentration is 0.0125g / ml, the CY-7 concentration is 50-100μmol / L, the adsorption time is 12-48 hours, and the adsorption is completed by centrifugation; During the in-situ self-polymerization, the DA concentration in the solution is 6-12 mg / ml, and the concentration of the ZIF-8 nanoparticles loaded with CY-7 is 50-100 mg / ml.

3. The method for preparing the nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function according to claim 2, characterized in that: The concentration of Zn(NO3)2·6H2O is 0.03-0.09 mol / L, and the concentration of 2-methylimidazole is 0.1-0.5 mol / L; the ultrasonic conditions are: 30-80 kHz, 60-150W ultrasonic equipment for 8-20 minutes; the high-speed centrifugation conditions are: 6000-12000 rpm, and the centrifugation time is 10-20 minutes; the centrifugation conditions after the adsorption are: high-speed centrifugation at 8000-10000 rpm at room temperature for 8-15 minutes; stirring is performed during the in-situ self-polymerization, the stirring rate is 800-1000 r / min, the reaction time is 4-8 hours, and high-speed centrifugation is performed after the reaction, the centrifugation rate is 8000-10000 rpm, and the centrifugation time is 8-15 minutes.

4. The method for preparing the nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function according to claim 1, characterized in that: In step 2), the amounts of 7-hydroxy-4-methylcoumarin, bromoacetic acid, and potassium carbonate in the solution are 50-125 mM, 250-350 mM, and 75-125 mM, respectively.

5. The method for preparing the nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function according to claim 1, characterized in that: Step 3) In the grafting reaction of 7-carboxymethoxy-4-methylcoumarin and CS-DA, the concentration of 7-carboxymethoxy-4-methylcoumarin is 1-3wt%, the concentration of CS-DA is 5-10wt%, the ratio of DMSO / deionized water mixed solvent is 10wt% DMSO / 90wt% deionized water, the EDC concentration is 0.025-0.06wt%, the NHS concentration is 0.04-0.08wt%, the coupling reaction time is 12-48 hours, and the magnetic stirring is 200-500 rpm during the reaction; the dialysis is performed in deionized water in the dark for 5-7 days.

6. The method for preparing the nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function according to claim 1, characterized in that: The concentration of CS-DA-CM in step 4) is 5-20 wt %; the amount of ZIF-8 / CY-7 / PDA particles is 5-20 mg / ml; and the angiogenic active component is one or more of a-FGF, b-FGF, PD-ECGF, TGF, TNF, and VEGF, and its concentration is 10-50 μg / ml.

7. A nanocomposite hydrogel dressing with reversible adhesion and photothermal sterilization function, characterized by: The method is prepared by the method according to any one of claims 1 to 6.

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