A salt-sensitive pure zwitterionic physical hydrogel as well as a preparation method and application thereof

Abstract

The application belongs to the field of biological medical materials, and particularly relates to a salt-sensitive zwitterionic physical hydrogel as well as a preparation method and application thereof. The PSBMA polymer is synthesized by a simple one-step method, and the PSBMA polymer can be customized into the salt-sensitive zwitterionic physical hydrogel according to ion concentration, which shows biodegradability and minimized foreign body reaction. The zwitterionic segment in the salt-sensitive zwitterionic physical hydrogel enables the salt-sensitive zwitterionic physical hydrogel to have antifouling capability. The salt-sensitive zwitterionic physical hydrogel of the application significantly reduces adhesion, increases biocompatibility and reduces organ toxicity, and effectively prevents postoperative tissue adhesion. The salt-sensitive zwitterionic physical hydrogel of the application is easy to use, and can be instantly adhered and fixed on an irregular surface. The salt-sensitive zwitterionic physical hydrogel can further be used as a drug delivery system for significantly prolonging drug release.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials, specifically relating to a salt-sensitive pure zwitterionic physical hydrogel, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Peritoneal adhesions (PA) are a common but serious postoperative clinical problem that can cause complex syndromes, including chronic abdominal pain, bowel obstruction, and female infertility. The risk of recurrent adhesions after surgery has been reported to be as high as 90%, leading to severe consequences and suffering for patients, and sometimes requiring a second surgery. Therefore, there is an urgent clinical need for a safe and effective anti-adhesion barrier to effectively prevent postoperative adhesions and recurrent adhesions.

[0004] To slow or prevent abdominal adhesions, a range of approaches have been employed, including improved surgical techniques, medications, and barrier materials. Improved minimally invasive surgery minimizes tissue damage during the procedure, reducing the likelihood of peritoneal adhesions. However, the complexity and unpredictability of surgical procedures make research into medications and barrier materials crucial. Medications that act on inflammation, fibroblasts, and mesothelial cells also have limited efficacy and serious side effects that may hinder the healing process.

[0005] Besides bioactive drugs, biocompatible physical barriers have become a research hotspot because they can prevent peritoneal adhesions (PA) formation by reducing contact between the wound and other tissues. Solutions, solid membranes or films, and hydrogels are currently the most commonly used biocompatible physical barriers. One study used saffron extract to cleanse the peritoneum and injured area to inhibit postoperative abdominal adhesions. Solutions are easy to use, but their retention time at the wound site is usually very limited. Some studies have used solid films to prevent postoperative peritoneal adhesions. However, the use of solid films requires good coverage of the injured area, and solid films that cannot adhere spontaneously also require suture fixation. Hydrogels have attracted increasing attention due to their longer retention time than solutions and better coverage than solid films.

[0006] Naturally derived biopolymer gels degrade rapidly, and their mechanical properties are difficult to control, resulting in limited protection against adhesion. In many studies, precursor solutions are injected into the injury site, and the gel forms through in vivo chemical reactions, which can be time-consuming and raises safety concerns. Furthermore, some physical hydrogels, such as those that transform from liquid to gel at body temperature, eliminate the need for in vivo chemical reactions or UV irradiation. However, this gelation process can be lengthy, prolonging surgical procedures and potentially increasing the risk of infection during surgery. Currently, many studies have achieved good anti-adhesion effects by applying pre-formed injectable gels to the injury site using syringes. However, the in vitro synthesis of these gels is complex; for example, some gels require polymerization under UV irradiation. Due to the aforementioned application-related issues, current physical barriers remain inadequate, only offering limited relief or reduction of adhesion. Therefore, suitable hydrogel barriers with specialized scaffold structures are needed to meet clinical needs. Moreover, the network structure of hydrogels makes them excellent drug carriers, allowing for broader therapeutic applications through drug loading. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a salt-sensitive pure zwitterionic physical hydrogel, its preparation method, and its applications.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a salt-sensitive pure zwitterionic physical hydrogel, comprising the following steps:

[0010] Methacrylethyl sulfobetaine was dissolved in deionized water to form a homogeneous solution. An initiator and an accelerator were added and stirred. The mixture was then subjected to polymerization under an inert atmosphere to obtain the PSBMA polymer.

[0011] PSBMA polymer was mixed with physiological saline to obtain a salt-sensitive pure zwitterionic physical hydrogel.

[0012] Secondly, the present invention provides a salt-sensitive pure zwitterionic physical hydrogel, which is obtained by the above-mentioned preparation method of salt-sensitive pure zwitterionic physical hydrogel.

[0013] Thirdly, the present invention provides the application of the above-mentioned salt-sensitive pure zwitterionic physical hydrogel as an isolation material.

[0014] Fourthly, the present invention provides the application of the above-mentioned salt-sensitive pure zwitterionic physical hydrogel in the preparation of hydrogel drug delivery systems.

[0015] Fifthly, the present invention provides a hydrogel drug delivery system comprising the above-mentioned salt-sensitive pure zwitterionic physical hydrogel and a drug.

[0016] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0017] (1) The present invention synthesizes PSBMA polymer through a simple one-step method. The PSBMA polymer can be customized into a transient hydrogel network according to the ion concentration to form a salt-sensitive pure zwitterionic physical hydrogel, which exhibits biodegradability and minimized foreign body reaction. The zwitterionic segments in the salt-sensitive pure zwitterionic physical hydrogel give it antifouling ability.

[0018] (2) Salt-sensitive pure zwitterionic physical hydrogel significantly reduces adhesion, increases biocompatibility and reduces organ toxicity. Salt-sensitive pure zwitterionic physical hydrogel is easy to use, can instantly adhere and fix on irregular surfaces, and stay in wounds for more than 10 days.

[0019] (3) Salt-sensitive pure zwitterionic physical hydrogels can further serve as drug delivery systems that significantly prolong drug release. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a schematic diagram of the structure of the salt-sensitive pure zwitterionic physical hydrogel of the present invention;

[0022] Figure 2 (a) is a scanning electron microscope image of the salt-sensitive pure zwitterionic physical hydrogel of Example 1; (b) is a physical image of the salt-sensitive pure zwitterionic physical hydrogel of Example 1; (c) is a frequency test curve of the storage modulus (G′) and loss modulus (G″) of the salt-sensitive pure zwitterionic physical hydrogels of Examples 1-3; (d) is a time scan curve of the storage modulus (G′) and loss modulus (G″) of the salt-sensitive pure zwitterionic physical hydrogels of Examples 1-3; (e) is a shear rate-viscosity curve of the salt-sensitive pure zwitterionic physical hydrogels of Examples 1-3; (f) is a degradation curve of the salt-sensitive pure zwitterionic physical hydrogels of Examples 1-3; (g) is a swelling curve of the salt-sensitive pure zwitterionic physical hydrogels of Examples 1-3; and (h) is a comparison of the protein adsorption capacity of the salt-sensitive pure zwitterionic physical hydrogels of Examples 1-3.

[0023] Figure 3(a) shows the toxicity test results of salt-sensitive pure zwitterionic physical hydrogels on 4T1 cells in Examples 1-3; (b) shows the toxicity test results of salt-sensitive pure zwitterionic physical hydrogels on L929 cells in Examples 1-3; (c) shows the live / dead staining results of salt-sensitive pure zwitterionic physical hydrogels on L929 cells in Examples 1-3; (d) shows the live / dead staining results of L929 cells embedded in salt-sensitive pure zwitterionic physical hydrogels in Example 1 at different times; (e) shows the adhesion test results of salt-sensitive pure zwitterionic physical hydrogels on L929 cells in Example 1.

[0024] Figure 4 The results of the tissue adhesion prevention effect assessment experiment are shown in the figure, where (a) is a schematic diagram of the tissue adhesion prevention effect assessment experiment, (b) is an adhesion score map, (c) is an optical image of the abdominal wall cecal injury model, and (d) is an image of hematoxylin-eosin (H&E) staining and Masson staining.

[0025] Figure 5 The results of the recurrent adhesion assessment experiment are shown in the following figures: (a) is a schematic diagram of the recurrent adhesion assessment experiment; (b) is an optical image of the recurrent adhesion model; (c) is a hematoxylin-eosin (H&E) staining image; (d) is a Masson staining image; (e) is an adhesion score graph; and (f) is a graph of weight change data in the recurrent adhesion model.

[0026] Figure 6 (a) is an in vivo imaging image of small animals in the drug retention experiment; (b) is a schematic diagram of the construction of a 4T1 breast cancer subcutaneous tumor recurrence model; (c) is a tumor volume-time change curve; (d) is a tumor volume comparison image; (e) is a tumor mass comparison image; (f) is a tumor optical image; (g) is a hematoxylin-eosin (H&E) staining image; and (h) is an in situ terminal transferase labeling (TUNEL) staining image. Among them, (1) Untreated group; (2) salt-sensitive pure zwitterionic physical hydrogel group (Blank gel) of Example 1; (3) Gel@STING; (4) Gel@DOX; (5) Gel@CuO2; (6) Gel@CuO2 / DOX; (7) Gel@M / CuO2 / DOX; and (8) Gel@M / CuO2 / DOX / STING Detailed Implementation

[0027] A first typical embodiment of the present invention provides a method for preparing a salt-sensitive pure zwitterionic physical hydrogel, comprising the following steps:

[0028] Methacrylethyl sulfobetaine (SBMA) was dissolved in deionized water to form a homogeneous solution. An initiator and an accelerator were added and stirred. The mixture was then subjected to polymerization under an inert atmosphere to obtain the PSBMA polymer.

[0029] PSBMA polymer was mixed with physiological saline to obtain a salt-sensitive pure zwitterionic physical hydrogel.

[0030] In one or more embodiments of this implementation, the concentration of methacryloylethyl sulfobetaine in the homogeneous solution is 0.1-0.3 g / mL.

[0031] In one or more embodiments of this implementation, the initiator is ammonium persulfate (APS), and the amount of the initiator is 0.05-0.5% of methacryloylethyl sulfobetaine;

[0032] The accelerator is tetramethylethylenediamine (TEMED), and the volume of the accelerator is 1-20 μL.

[0033] In one or more embodiments of this implementation, the inert atmosphere is argon or nitrogen.

[0034] In one or more embodiments of this implementation, the polymerization reaction temperature is 20-30°C and the polymerization reaction time is 10-20 hours.

[0035] In one or more embodiments of this implementation, the mass-to-volume ratio of PSBMA to physiological saline is 2-6:8-4 g / mL.

[0036] A second typical embodiment of the present invention provides a salt-sensitive pure zwitterionic physical hydrogel, obtained by the above-described method for preparing salt-sensitive pure zwitterionic physical hydrogel.

[0037] like Figure 1 As shown, PSBMA can self-assemble into a salt-sensitive pure zwitterionic physical hydrogel in physiological saline. With the increase of NaCl concentration, the salt-sensitive pure zwitterionic physical hydrogel exhibits a hydrogel-to-solution transition. This makes the salt-sensitive pure zwitterionic physical hydrogel of the present invention dissociable under physiological conditions and has strong anti-protein adsorption properties, which can minimize foreign body reactions.

[0038] In a third typical embodiment of the present invention, the above-mentioned salt-sensitive pure zwitterionic physical hydrogel is used as an isolation material.

[0039] The fourth typical embodiment of the present invention describes the application of the above-mentioned salt-sensitive pure zwitterionic physical hydrogel in the preparation of a hydrogel drug delivery system.

[0040] The fifth typical embodiment of the present invention is a hydrogel drug delivery system, comprising the above-mentioned salt-sensitive pure zwitterionic physical hydrogel and a drug.

[0041] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0042] Example 1

[0043] Weigh 1 g of SBMA and place it in a vial, then add 5 mL of deionized water. After the monomer has completely dissolved and formed a homogeneous solution, add 0.1 mol% APS of SBMA monomer and 10 μL of TEMED to the solution and stir for another 10 minutes. Under nitrogen protection, carry out the polymerization reaction at 25 °C for 12 hours to obtain the PSBMA polymer.

[0044] Mix 0.5g PSBMA with 0.5mL physiological saline and let stand at room temperature to obtain a 50% salt-sensitive pure zwitterionic physical hydrogel.

[0045] like Figure 2 As shown in Figure a, the salt-sensitive pure zwitterionic physical hydrogel has a porous and interconnected internal structure. Figure 2 As shown in b, the salt-sensitive pure zwitterionic physical hydrogel is a transparent and colorless gel.

[0046] Example 2

[0047] Unlike Example 1, 0.4 g PSBMA and 0.6 mL physiological saline were mixed and allowed to stand at room temperature to obtain a 40% salt-sensitive pure zwitterionic physical hydrogel.

[0048] Example 3

[0049] Unlike Example 1, 0.3g PSBMA and 0.7mL physiological saline were mixed and allowed to stand at room temperature to obtain a 30% salt-sensitive pure zwitterionic physical hydrogel.

[0050] Example 4

[0051] 20 mg CuCl2·2H2O, 500 mg PVP, and 2 mg DOX·HCl were dissolved in 3 mL of deionized water and stirred at room temperature for 60 minutes. Then, 1 mL of NaOH solution (containing 10 mg of sodium hydroxide) was added to the mixture. -1 Add 4 μL of H2O2 and stir the resulting mixture at 25 °C for 12 hours to prepare CuO2 / DOX. Collect the product by centrifugation and wash three times with deionized water. Mix the prepared CuO2 / DOX with macrophage membrane and sonicate in a water bath for 30 minutes to obtain M / CuO2 / DOX.

[0052] 7 mg M / CuO2 / DOX and 200 μg of the STING agonist 2',3'-cGAMP were dispersed in 0.5 mL of physiological saline and mixed with 0.5 g of PSBMA powder from Example 1 to obtain the Gel@M / CuO2 / DOX / STING hydrogel drug delivery system.

[0053] Comparative Example 1

[0054] 20 mg CuCl2·2H2O and 500 mg PVP were dissolved in 3 mL of deionized water and stirred at room temperature for 60 minutes. Then, 1 mL of NaOH solution (containing 10 mg of PVP) was added to the mixture. -1 Add 4 μL of H2O2 and stir the resulting mixture at 25 °C for 12 hours to prepare CuO2. Collect the product by centrifugation and wash three times with deionized water.

[0055] 7 mg CuO2 was dispersed in 0.5 mL of physiological saline and mixed with 0.5 g of PSBMA powder from Example 1 to obtain Gel@CuO2.

[0056] Comparative Example 2

[0057] 500 μg of DOX·HCl was dispersed in 0.5 mL of physiological saline and mixed with 0.5 g of PSBMA powder from Example 1 to obtain Gel@DOX.

[0058] Comparative Example 3

[0059] 200 μg of the STING agonist 2',3'-cGAMP was dispersed in 0.5 mL of physiological saline and mixed with 0.5 g of PSBMA powder from Example 1 to obtain Gel@STING.

[0060] Comparative Example 4

[0061] Unlike Example 4, CuO2 / DOX was used instead of M / CuO2 / DOX, and the STING agonist 2',3'-cGAMP was omitted, resulting in Gel@CuO2 / DOX.

[0062] Comparative Example 5

[0063] Unlike Example 4, the STING agonist 2',3'-cGAMP was omitted, resulting in Gel@M / CuO2 / DOX.

[0064] Experimental Example 1

[0065] Characterization of salt-sensitive pure zwitterionic physical hydrogels

[0066] The rheological behavior of salt-sensitive pure zwitterionic physical hydrogels was studied by a rheometer. As Figure 2 shown in c, the frequency sweep results showed that within the tested frequency range (0.1 - 100 Hz), the G′ and G″ values of the 30% and 40% hydrogels increased with increasing frequency, showing fluid-like behavior at lower frequencies (G′ < G″) and solid-like behavior at higher frequencies (G' > G″). The G' value of the 50% hydrogel was higher than G″ within the frequency sweep range. With further increase in frequency, the three-dimensional network was gradually damaged (G′ < G″). As Figure 2 shown in d, in the time sweep curve, the G' values of all hydrogels were always greater than the corresponding G″ at 1 Hz and 1% strain, indicating the presence of stable solid-like behavior. As Figure 2 shown in e, with the increase in shear rate, the viscosity of the hydrogel decreased, which demonstrated its shear-thinning behavior, which is beneficial for anti-abdominal adhesion surgery by injection.

[0067] As an implant material, the degradation property is also an important factor for in vivo application, which may prevent the second operation of implant retrieval. As Figure 2 shown in f, with the passage of time, the positive and negative ions shielded the crosslinking points and gradually dissociated the hydrogel backbone, resulting in hydrogel degradation. It can be clearly observed that with the increase in the mass of PSBMA, the degradation time increased, probably because a higher crosslinking density of the hydrogel requires more ions for shielding effect. The results showed that the salt-sensitive pure zwitterionic physical hydrogel could degrade in an in vitro environment simulating physiological conditions and could finally completely dissociate in the physiological environment.

[0068] As Figure 2 shown in g, the salt-sensitive pure zwitterionic physical hydrogel absorbed water molecules in a short time, attributed to the super hydrophilicity of the PSBMA polymer. With the decrease in the mass fraction of the PSBMA polymer, the swelling degree of the hydrogel increased. A higher mass fraction would result in more physical crosslinking points in the hydrogel, which would lead to smaller cavities in the hydrogel, thus limiting water adsorption. On the contrary, the fewer crosslinking points in the hydrogel, the larger the cavities and the higher the swelling degree.

[0069] The anti-protein adsorption of the gel was detected by a BSA detection kit. In the experiment, a TCPS cell culture plate was used as the protein adsorption material, and its protein adsorption amount was set to 100%. The experimental results are as Figure 1 shown in h. Compared with the TCPS group, the protein adsorption ability of the salt-sensitive pure zwitterionic physical hydrogel was less than 6%.

[0070] In vitro cytotoxicity and cell adhesion behavior

[0071] As Figure 3As shown in a and 3b, the viability of mouse breast cancer cells (4T1) and mouse fibroblasts (L929) was higher than 90%, indicating that the salt-sensitive pure zwitterionic physical hydrogel has very low cytotoxicity. Figure 3 As shown in Figure c, compared with the blank control group, the vast majority of L929 cells treated with the salt-sensitive pure zwitterionic physical hydrogel extract were viable cells, exhibiting green fluorescence, indicating that the salt-sensitive pure zwitterionic physical hydrogel has excellent cell compatibility. The cells were encapsulated in the salt-sensitive pure zwitterionic physical hydrogel of Example 1, as follows... Figure 3 As shown in d, the number of cells in the hydrogel increases significantly with the extension of culture time.

[0072] To further explore its ability to prevent abdominal adhesion, L929 was used to evaluate its cell adhesion. Figure 2 As shown in Figure e, after incubation at 37°C for different time periods, the surface of the control group (TCPS) showed partial coverage of L929 cells within 4 hours of incubation and complete cell coverage within 24 hours. However, cells hardly adhered to the salt-sensitive pure zwitterionic physical hydrogel surface of Example 1.

[0073] Evaluation of the preventive effect of tissue adhesion in an abdominal wall cecal injury model

[0074] like Figure 4 As shown in Figure a, an abdominal wall cecal injury model was constructed. 1 mL of physiological saline (control group), hyaluronic acid hydrogel (HA hydrogel, purchased from Hangzhou Xiehe Medical Supplies Co., Ltd.), and the salt-sensitive pure zwitterionic physical hydrogel of Example 1 were applied to rats.

[0075] On days 7 and 14 post-surgery, the abdominal cavity was opened to examine and score adhesions. Optical images are shown below. Figure 4 As shown in Figure c. In the control group, severe abdominal adhesions and significant ascites were observed on days 7 and 14. After treatment with HA hydrogel, adhesions were alleviated compared to the control group. This is likely due to the presence of hyaluronidase in the body, which readily degrades HA hydrogel, leading to a decrease in its anti-adhesion effect. Salt-sensitive pure zwitterionic physical hydrogels can significantly reduce adhesion. A standard adhesion scoring system was used for scoring: 0 points, no adhesion; 1 point, slight adhesion; 2 points, moderate adhesion; 3 points, severe adhesion. Figure 4 As shown in b, most animals in salt-sensitive pure zwitterionic physical hydrogels did not exhibit adhesion, and even if adhesion occurred, the degree of adhesion was very low (1 point).

[0076] To further evaluate the effects of the hydrogel on the abdominal wall and cecal surface, local tissues were stained for H&E and Masson analysis. Figure 4As shown in Figure d, on day 7 post-surgery, dense adhesions were observed between the abdominal wall and cecum in the control group. The adhesion layer in the HA group was looser compared to the control group. In the salt-sensitive pure zwitterionic physical hydrogel group, the abdominal wall and cecum separated, showing significant improvement compared to the HA hydrogel group and the control group. However, some inflammatory cells were observed in the mesothelial layer, indicating that the tissue was in the recovery phase.

[0077] On day 14 post-surgery, the adhesion tissue between the abdominal wall and cecum was denser in the control group compared to day 7. Furthermore, prominent blood vessels were observed in the adhesion tissue. Similar results were observed in the HA hydrogel group, with a degree of adhesion between the abdominal wall and cecum, which was denser than on day 7. For the salt-sensitive pure zwitterionic physical hydrogel group, inflammation on the wound surface was significantly reduced, and fibrin previously caused by inflammatory cells was gradually degraded and absorbed, showing excellent recovery, similar to normal tissue. All these results indicate that salt-sensitive pure zwitterionic physical hydrogels can effectively prevent abdominal adhesions.

[0078] Recurrent adhesions occur frequently and are more complex and difficult to prevent than primary adhesions. Currently, few treatments are available for recurrent adhesions. Therefore, a recurrent adhesion model was established to evaluate the effect of a salt-sensitive pure zwitterionic physical hydrogel on recurrent adhesions. First, an abdominal wall-cecal injury model was established, with no treatment in each group. After 7 days, adhesion lysis was performed, with each group treated with physiological saline (control group), HA hydrogel, or the salt-sensitive pure zwitterionic physical hydrogel of Example 1. The model construction process is as follows: Figure 5 As shown in Figure a. Seven days after the adhesions were released, the abdominal cavity was opened to observe the adhesions, and the optical images are as follows. Figure 5 As shown in b. H&E and Masson analyses are as follows: Figure 5 c. Figure 5 As shown in d. Figure 5 As shown in e, in the model group, all 6 rats exhibited severe adhesions (3 points), and HA hydrogel treatment only slightly alleviated recurrent adhesions. However, treatment with salt-sensitive pure zwitterionic physical hydrogels achieved almost complete prevention: on day 7, 4 out of 6 animals had no adhesions (0 points), and 2 out of 6 animals had mild adhesions (1 point). Figure 5 As shown in f, there was no significant difference in body weight change in mice 7 days post-surgery. The results indicate that salt-sensitive pure zwitterionic physical hydrogels can effectively prevent recurrent adhesions.

[0079] Experimental Example 2

[0080] 100 μL of salt-sensitive pure zwitterionic physical hydrogel or free rhodamine B loaded in Example 1 was injected into the tumor cavity after surgical resection. Figure 6As shown in Figure a, fluorescence results indicated that almost no free Rhodamine B fluorescence signal was detected after 24 hours, while the fluorescence signal of Rhodamine B loaded into the salt-sensitive pure zwitterionic physical hydrogel remained at a high level even after 7 days. These results demonstrate that the salt-sensitive pure zwitterionic physical hydrogel is a drug delivery system that significantly prolongs drug release.

[0081] like Figure 6 As shown in b, a subcutaneous tumor recurrence model of 4T1 breast cancer was established to evaluate the in vivo therapeutic effect of this agent (100 μL of the agent was injected into each mouse). Tumor volume, body weight, and growth in mice were monitored during treatment. Figure 6 As shown in Figure c, tumors in mice in the untreated group, the salt-sensitive pure zwitterionic physical hydrogel group of Example 1, and the Gel@STING group grew rapidly. Compared with the untreated group, Gel@DOX, Gel@CuO2, and Gel@CuO2 / DOX also showed recurrence, but the tumor volume was smaller than the first three groups. The recurrence rate in the Gel@M / CuO2 / DOX group was reduced to 60%. As expected, the postoperative local tumor recurrence rate was significantly reduced after treatment with Gel@M / CuO2 / DOX / STING, and the inhibition rate of residual 4T1 tumors was 100%. Figure 6 As shown in df, the tumor volume and weight in the Gel@M / CuO2 / DOX / STING treatment group were much smaller than those in the other groups.

[0082] TUNEL immunofluorescence and H&E staining are used to study apoptosis of tumor cells in in situ tumor tissues. For example... Figure 6 g、 Figure 6 As shown in h, tumor sections from the Gel@M / CuO2 / DOX / STING group exhibited extensive green fluorescence and cell debris, indicating significant tumor cell apoptosis. The untreated group and the salt-sensitive pure zwitterionic physical hydrogel group from Example 1 showed almost no green fluorescence and cell debris, indicating that the carrier material could not induce tumor cell apoptosis. Other groups also showed less green fluorescence and nuclear debris.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Application of salt-sensitive zwitterionic physical hydrogel in preparation of hydrogel drug delivery system: the drug in the drug delivery system is DOX and STING agonist 2', 3'-cGAMP; the salt-sensitive zwitterionic physical hydrogel has self-adhesion, biodegradability, antifouling performance and biocompatibility; wherein a preparation method of the salt-sensitive zwitterionic physical hydrogel, comprising the following steps: dissolve methacryloyl ethyl sulfobetaine in deionized water to form a uniform solution, add an initiator and an accelerator to stir and mix, and perform a polymerization reaction under the protection of an inert atmosphere to obtain a PSBMA polymer; in the uniform solution, the concentration of methacryloyl ethyl sulfobetaine is 0.1-0.3 g / mL; the initiator is ammonium persulfate, and the amount of substance of the initiator is 0.05-0.5% of methacryloyl ethyl sulfobetaine; the accelerator is tetramethyl ethylenediamine, and the volume of the accelerator is 1-20 μL; mix the PSBMA polymer with physiological saline to obtain a salt-sensitive zwitterionic physical hydrogel; the mass-volume ratio of the PSBMA to physiological saline is 2-6:8-4 g / mL; the temperature of the polymerization reaction is 20-30 ℃; a preparation method of the drug delivery system, comprising the following steps: 20 mg CuCl2.2H2O, 500 mg PVP and 2 mg DOX.HCl were dissolved in 3 mL deionized water and stirred for 60 minutes at room temperature to obtain mixture a; 1 mL NaOH solution with a concentration of 10 mg mL -1 and 4 μL H2O2 were added to the mixture a to obtain mixture b, and the mixture b was stirred at 25 °C for 12 hours to prepare CuO2 / DOX; the CuO2 / DOX was collected by centrifugation and washed with deionized water for three times; the prepared CuO2 / DOX was mixed with the macrophage membrane and ultrasonically treated in a water bath for 30 minutes to obtain M / CuO2 / DOX; dispersing 7 mg M / CuO2 / DOX and 200 μg STING agonist 2', 3'-cGAMP in 0.5 mL physiological saline and mixing with 0.5 g PSBMA polymer powder to obtain a Gel@M / CuO2 / DOX / STING hydrogel drug delivery system.

2. Application of salt-sensitive zwitterionic physical hydrogel in preparation of isolation material; the isolation is to prevent adhesion, and the adhesion includes cell adhesion, tissue adhesion or recurrent adhesion; the cell adhesion is abdominal adhesion, and the tissue adhesion and recurrent adhesion are abdominal wall cecal adhesion; wherein a preparation method of the salt-sensitive zwitterionic physical hydrogel, comprising the following steps: dissolve methacryloyl ethyl sulfobetaine in deionized water to form a uniform solution, add an initiator and an accelerator to stir and mix, and perform a polymerization reaction under the protection of an inert atmosphere to obtain a PSBMA polymer; in the uniform solution, the concentration of methacryloyl ethyl sulfobetaine is 0.1-0.3 g / mL; the initiator is ammonium persulfate, and the amount of substance of the initiator is 0.05-0.5% of methacryloyl ethyl sulfobetaine; the accelerator is tetramethyl ethylenediamine, and the volume of the accelerator is 1-20 μL; mix the PSBMA polymer with physiological saline to obtain a salt-sensitive zwitterionic physical hydrogel; the mass-volume ratio of the PSBMA to physiological saline is 2-6:8-4 g / mL; the temperature of the polymerization reaction is 20-30 ℃.

3. Use according to claim 1 or 2, characterized in that, the inert atmosphere is argon or nitrogen.

4. Use according to claim 1 or 2, wherein the compound is ###0002### the time of the polymerization reaction is 10-20 h.

Images