Dithioformate-metal coordination two-dimensional network material, composite hydrogel and application thereof

Abstract

The application discloses a kind of dithiocarbamate-metal coordination two-dimensional network materials, composite hydrogel and its application, belong to the field of biomedical materials.P-phenylenediamine, carbon disulfide are used as raw materials, water is used as solvent, and ammonia is used as catalyst to prepare p-phenylenediamine ammonium dithiocarbamate (DTC);Then trivalent metal salt is reacted with DTC to form two-dimensional network material.Two-dimensional network material is incorporated into chemical crosslinking polyvinyl alcohol / polyethylene glycol hydrogel, and the composite hydrogel has excellent mechanical properties, good antibacterial performance and free radical scavenging effect to slow down inflammation.Through experiments, it is proved that the tissue used for intervertebral disc nucleus degenerative disease has good development, can effectively show the injection and filling effect of hydrogel, and provides a new direction for the treatment of intervertebral disc nucleus degenerative disease.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biomedical materials, and particularly relates to a kind of dithioformate-metal coordination two-dimensional network materials, composite hydrogel and application thereof. BACKGROUND

[0002] Intervertebral disc nucleus degenerative disease is one of the main causes of low back pain (Clinical Medicine Progress, 2020, 10(10): 2302-2310), and its pathological features are dehydration of nucleus pulposus tissue, loss of proteoglycan, and disorder of collagen fiber structure, accompanied by massive release of inflammatory factors (such as IL-1β, TNF-α) and macrophage infiltration, ultimately leading to decreased intervertebral disc height, loss of mechanical function, and severely affecting the quality of life of patients.

[0003] Current clinical treatment methods have obvious limitations: conservative treatment (such as anti-inflammatory drugs, physical therapy) can only relieve symptoms and cannot stop disease progression; surgical treatment (such as discectomy, spinal fusion) can relieve nerve compression, but has risks such as postoperative adjacent segment degeneration and loss of spinal mobility; Patent CN202510054848.0 reports a composite hydrogel of animal glue, polyvinyl alcohol, glycerol and water, which has similar rheological and mechanical properties to natural nucleus pulposus and also has tissue adhesion, but animal glue can cause immune response. Patents such as CN20221121835.0 report crosslinking agent and hydrogel precursor solution packaged independently, which can form hydrogel quickly under mild conditions after adding crosslinking agent into the hydrogel precursor solution, and this repair product can be shaped in vivo during injection, but since hydrogel polymer precursor solution is used, it has certain toxicity, and the crosslinking formed by metal ion coordination will degrade over time. The ideal hydrogel formula for nucleus pulposus filling should have mechanical properties matching natural nucleus pulposus, variable flowability to ensure smooth injection, certain antibacterial and anti-inflammatory and tissue repair activity, no toxic small molecules, high stability, and imaging performance for easy observation of injection molding performance. According to the above standards, there is no related patent and product reported in China at present.

[0004] Metal-coordinated two-dimensional network materials have unique structures (J. Am. Chem. Soc. 2021, 143, 37; Chemical Engineering Journal, 2024, 488, 150945), good chemical stability and biological activity, and can realize anti-inflammatory, antibacterial, and imaging functions by regulating ion release. Polyvinyl alcohol (PVA), polyvinylpyrrolidone, and polyethylene glycol diglycidyl ether are biologically approved materials by the US FDA (Adv. Mater. 2024, 36, 2306326). The hydrogel structure and mechanical properties prepared by them are highly similar to those of natural nucleus pulposus tissue, and are ideal nucleus pulposus replacement carriers. The combination of metal-coordinated two-dimensional network materials and hydrogels is expected to prepare a new type of nucleus pulposus repair material with multiple functions of mechanical support, antibacterial, anti-inflammatory repair, and imaging, and to provide a new strategy for the treatment of intervertebral disc nucleus degenerative diseases. However, existing nucleus replacement materials (such as pure polyvinyl alcohol hydrogel and collagen scaffold) have low matching degree with natural nucleus pulposus in terms of mechanical properties, lack anti-inflammatory and tissue repair activity, and are difficult to achieve long-term efficacy. At the same time, the specific surface area of the material is small, the active site is small, the hydrogel is difficult to efficiently composite, and there is a lack of precise functional design for the microenvironment of nucleus pulposus lesions, which is difficult to meet the clinical treatment needs. SUMMARY

[0005] In view of the deficiencies of the existing treatment methods for intervertebral disc nucleus degenerative diseases, the present application provides a kind of dithioformate-metal coordinated two-dimensional network material, composite hydrogel and its application. The dithioformate-metal coordinated two-dimensional network material has good bactericidal and anti-inflammatory effects on Escherichia coli or Staphylococcus aureus. The composite hydrogel prepared therefrom realizes the unification of mechanical support, anti-inflammatory repair and imaging, and is expected to effectively delay or even reverse the progression of intervertebral disc nucleus degenerative diseases, and has good application prospects.

[0006] To solve the problems of the prior art, the technical scheme adopted by the present application is as follows:

[0007] A preparation method of a dithioformate-metal coordinated two-dimensional network material, comprising the following steps:

[0008] Step 1: Dissolve p-phenylenediamine in slightly hot water at 30-40℃, and then add ammonia water and carbon disulfide in sequence, with a molar ratio of p-phenylenediamine to carbon disulfide being 1:2. React at a temperature lower than 20℃ for 2-3 hours, then filter and sequentially wash with anhydrous ethanol and diethyl ether, and vacuum dry at 40℃ for 12 hours to obtain ammonium p-phenylenediamine dithioformate;

[0009] Step 2, dissolve the p-phenylenediamine ammonium bis-thiocarbamate and metal salt in anhydrous ethanol respectively, then mix the two solutions uniformly, and the molar ratio of p-phenylenediamine ammonium bis-thiocarbamate to metal salt is 3:2, reflux at 80℃ for 0.5 hours, then wash with water and ethanol respectively, and vacuum dry at 60℃ for 12 hours, to obtain a kind of bis-thiocarbamate-metal coordination two-dimensional network material, denoted as M-DTC.

[0010] As an improvement, the metal salt in step 2 is bismuth nitrate, cerium chloride, bismuth chloride, cerium sulfate or ferric chloride.

[0011] The kind of bis-thiocarbamate-metal coordination two-dimensional network material prepared by any of the above methods has a highly ordered two-dimensional network structure.

[0012] A composite hydrogel with antibacterial and anti-inflammatory imaging functions, comprising the above-mentioned bis-thiocarbamate-metal coordination two-dimensional network material.

[0013] The preparation method of the above-mentioned composite hydrogel with antibacterial and anti-inflammatory imaging functions, dissolving polyvinyl alcohol and polyvinylpyrrolidone in deionized water at a mass ratio of 110:1 to prepare a polyvinyl alcohol / polyvinylpyrrolidone mixed solution with a concentration of 12.6-20.0wt%, sterilizing at 121℃ and 26KPa for 30 minutes, cooling to 75±5℃ for standby; adding the bis-thiocarbamate-metal coordination two-dimensional network material to the polyvinyl alcohol / polyvinylpyrrolidone mixed solution at a proportion of 0.1wt%, and mechanically stirring thoroughly; then adding polyethylene glycol diglycidyl ether, and the polyethylene glycol diglycidyl ether accounts for 8-15% of the total mass of the mixed solution, then adding 0.3wt% glycerol, and then adding 10M sodium hydroxide solution as a catalyst, stirring at 70℃ for 10 minutes, and then reacting at 60-70℃ for 10-20 hours, then placing the product in a dialysis bag, purifying with 0.65MPa polyethylene glycol permeate solution at 37℃ for 7 days to remove unreacted impurities, then sterilizing at 121℃ and 26KPa for 30 minutes, and then injecting into a mold after cooling, and forming at 25℃ to obtain a metal coordination two-dimensional network material doped hydrogel.

[0014] As an improvement, the molecular weight of polyvinyl alcohol is 145kDa, the molecular weight of polyvinylpyrrolidone is 58kDa, the molecular weight of polyethylene glycol diglycidyl ether is 526Da, the molecular weight cut-off of the dialysis bag is 3500Da, and the molecular weight of the polyethylene glycol is 20kDa.

[0015] The application of the above-mentioned kind of bis-thiocarbamate-metal coordination two-dimensional network material or the above-mentioned composite hydrogel with antibacterial and anti-inflammatory imaging functions in the preparation of a drug for treating intervertebral disc nucleus degenerative disease.

[0016] Beneficial effects:

[0017] The application discloses a dithioformate-metal coordination two-dimensional network material, a composite hydrogel and application thereof, and relates to the field of biomaterials.

[0018] (1) The dithioformate-metal coordination two-dimensional network material is obtained by reacting ammonium dithioformate and trivalent metal salt, the antioxidation effect of ammonium dithioformate is improved, and the metal salts defined in the application have their own advantages, for example, iron elements promote the activity of related enzymes in the body, regulate redox reactions, resist oxidative stress, and after coordination of iron ions and ammonium carbamate compounds, the antioxidation capacity is possibly enhanced, thereby slowing down the degenerative changes of intervertebral discs; bismuth ions have strong anti-inflammatory effects and have potential effects on tissue repair and regeneration, after coordination of bismuth ions and ammonium carbamate compounds, the degenerative damage is possibly reduced by inhibiting the release of inflammatory factors in intervertebral discs and promoting cell repair; cerium ions have antioxidation properties, can eliminate free radicals in the body, and reduce cell damage caused by oxidative stress; in addition, cerium can promote the activity of part of enzymes in the body and improve cell repair and regeneration.

[0019] (2) The two-dimensional network structure of the dithioformate-metal coordination two-dimensional network material provides more surface active sites, metal ions can better bind to receptors on the surface of bacteria or interfere with the metabolic process of bacteria, which helps to improve the ROS removal capacity of the material, reduce inflammation-related oxidative damage, and inhibit the occurrence and development of inflammation. Meanwhile, the ion release effect of the metal coordination two-dimensional network material is utilized to realize the anti-inflammatory and tissue repair functions.

[0020] (3) The structure of the metal coordination two-dimensional network material can enhance the chemical stability and biological activity of the hydrogel, the hydrogel matrix provides a stable carrier for the metal coordination two-dimensional network material, and the two synergistically improve the material performance; during the preparation process, the PVA / PVP concentration, the PEG-DGE crosslinking degree and the doping amount of the metal coordination two-dimensional network material are adjusted, so that the mechanical properties of the hydrogel match the natural nucleus pulposus. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The application discloses a dithioformate-metal coordination two-dimensional network material, a composite hydrogel and application thereof, and relates to the field of biomaterials.

[0022] Figure 2Flow chart for treating nucleus pulposus degenerative diseases by using the dithiocarbamate-metal coordination two-dimensional network material doped composite hydrogel of the present application;

[0023] Figure 3 XRD pattern of dithiocarbamate-metal coordination two-dimensional network material prepared by using different metal salts;

[0024] Figure 4 Infrared spectrum of dithiocarbamate-metal coordination two-dimensional network material prepared by using different metal salts;

[0025] Figure 5 NMR spectrum of p-phenylenediamine ammonium dithiocarbamate (DTC) prepared by the present application 13 C spectrum;

[0026] Figure 6 NMR spectrum of dithiocarbamate-Fe 3+ coordination two-dimensional network material (Fe-DTC) prepared by the present application 13 C spectrum;

[0027] Figure 7 NMR spectrum of dithiocarbamate-Bi 3+ coordination two-dimensional network material (Bi-DTC) prepared by the present application 13 C spectrum;

[0028] Figure 8 NMR spectrum of dithiocarbamate-Ce 3+ coordination two-dimensional network material (Ce-DTC) prepared by the present application 13 C spectrum;

[0029] Figure 9 Scanning electron microscope image and element distribution spectrum of DTC prepared by the present application;

[0030] Figure 10 Scanning electron microscope image and element distribution spectrum of Fe-DTC prepared by the present application;

[0031] Figure 11 Scanning electron microscope image and element distribution spectrum of Bi-DTC prepared by the present application;

[0032] Figure 12 Scanning electron microscope image and element distribution spectrum of Ce-DTC prepared by the present application;

[0033] Figure 13 Test record of oxygen production of different materials;

[0034] Figure 14 Antibacterial test results of dithiocarbamate-metal coordination two-dimensional network material prepared by the present application;

[0035] Figure 15 Physical pictures of the dithiocarbamate-metal coordination two-dimensional network material prepared by different metal salts doped in hydrogel;

[0036] Figure 16 Pictures of the gel-sol transition process and the sol injectability for different compositions;

[0037] Figure 17 Elastic response pictures of the hydrogel doped with the dithiocarbamate-metal coordination two-dimensional network material prepared by different metal salts;

[0038] Figure 18 Viscous response pictures of the hydrogel doped with the dithiocarbamate-metal coordination two-dimensional network material prepared by different metal salts;

[0039] Figure 19 Viscoelasticity test of the hydrogel doped with the dithiocarbamate-metal coordination two-dimensional network material prepared by different metal salts;

[0040] Figure 20 Complex viscosity test of the hydrogel doped with five samples;

[0041] Figure 21 X-DR image of the X-ray after injecting the hydrogel into the intervertebral disc nucleus of a sheep in vitro. DETAILED DESCRIPTION

[0042] The raw materials used in the present application are all existing products, and the specific preparation method and performance test are conventional technologies.

[0043] The pressure of the autoclaving used in the present application is 26 KPa.

[0044] The present application reacts p-phenylenediamine with carbon disulfide in an alkaline solution to obtain the p-phenylenediamine ammonium dithiocarbamate ligand; reacts a metal salt with the p-phenylenediamine ammonium dithiocarbamate ligand material in an aqueous solution to obtain the metal coordination dithiocarbamate salt derivative. The synthesis steps are as shown in Figure 1 .

[0045] Example 1 Synthesis of p-phenylenediamine ammonium dithiocarbamate (DTC)

[0046] 5.4 g of p-phenylenediamine is dissolved in 10 mL of slightly hot water at 35℃, and then 18 mL of 25% ammonia water and 6 mL of carbon disulfide are sequentially added. Stirring is performed at 0℃ for 3 h. After the reaction is completed, filtration is performed, and ethanol and diethyl ether are used for washing, respectively. Finally, the obtained solid product is placed in a vacuum drying oven at 40℃ for drying for 12 h to obtain ammonium dithiocarbamate (DTC).

[0047] Example 2 Dithiocarbamate-Fe3+ Synthesis of a coordinated two-dimensional network material (Fe-DTC)

[0048] DTC and FeCl3 were dissolved in equal volume of absolute ethanol in the ratio of 3:2 respectively, then the ethanol solution of FeCl3 was slowly added to the ethanol solution of DTC. The mixed solution was refluxed at 80 °C for 0.5 h. After the reaction was completed, it was filtered, washed with water and ethanol respectively, and the solid product obtained was dried under vacuum at 60 °C for 12 h to obtain the product as Fe-DTC.

[0049] Example 3 Dithiocarbamate-Bi 3+ Synthesis of a coordinated two-dimensional network material (Bi-DTC)

[0050] DTC and BiCl3 were dissolved in equal volume of absolute ethanol in the ratio of 3:2 respectively, then the aqueous solution of BiCl3 was slowly added to the ethanol solution of DTC. The mixed solution was refluxed at 80 °C for 0.5 h. After the reaction was completed, it was filtered, washed with water and ethanol respectively, and the solid product obtained was dried under vacuum at 60 °C for 12 h to obtain the product as Bi-DTC.

[0051] Example 4 Dithiocarbamate-Ce 3+ Synthesis of a coordinated two-dimensional network material (Ce-DTC)

[0052] DTC and CeCl3 were dissolved in equal volume of absolute ethanol in the ratio of 3:2 respectively, then the ethanol solution of CeCl3 was slowly added to the ethanol solution of DTC. The mixed solution was refluxed at 80 °C for 0.5 h. After the reaction was completed, it was filtered, washed with water and ethanol respectively, and the solid product obtained was dried under vacuum at 60 °C for 12 h to obtain the product as Ce-DTC. 3+

[0053] Comparative Example 1

[0054] Except that the ferric chloride in Example 2 was replaced by NiCl2, the rest of the operations were the same, and a dithiocarbamate metal-coordinated one-dimensional polymer long chain was obtained, which was recorded as Ni-DTC.

[0055] Comparative Example 2

[0056] Except that the ferric chloride in Example 2 was replaced by ZnCl2, the rest of the operations were the same, and a dithiocarbamate metal-coordinated one-dimensional polymer long chain was obtained, which was recorded as Zn-DTC.

[0057] Comparative Example 3

[0058] Except that the ferric chloride in Example 2 was replaced by MnCl2, the rest of the operations were the same, and a dithiocarbamate metal-coordinated one-dimensional polymer long chain was obtained, which was recorded as Mn-DTC. ​

[0059] The materials prepared in Examples 1-4 and Comparative Examples 1-3 were tested, and the results are shown in Table 1 and FIGS. 1-4. Figures 3-12

[0060] Figure 3 XRD patterns of the dithiocarbamate-metal coordination two-dimensional network materials prepared from different metal salts.

[0061] Figure 4 Infrared spectra of the dithiocarbamate-metal coordination two-dimensional network materials prepared from different metal salts.

[0062] Figure 5 NMR1H spectra of DTC; 13 Figure 6 NMR1H spectra of Fe-DTC; 13 Figure 7 NMR1H spectra of Bi-DTC; 13 Figure 8 NMR1H spectra of Ce-DTC; 13 From the NMR1H spectra, it can be seen that C atoms in different chemical environments correspond to different peaks. 13

[0063] Figure 9 SEM images and element distribution maps of DTC; Figure 10 SEM images and element distribution maps of Fe-DTC; Figure 11 SEM images and element distribution maps of Bi-DTC; Figure 12 SEM images and element distribution maps of Ce-DTC.

[0064] The successful synthesis of the materials can be proved by the XRD patterns and infrared spectra. From the element distribution maps of the SEM, it can be seen that the Fe, Bi, and Ce elements are uniformly distributed in the corresponding materials.

[0065] Table 1 is the specific surface area values of the dithiocarbamate-metal coordination two-dimensional network and one-dimensional long-chain polymers

[0066] Materials BET surface area (m 2 / g) Fe-DTC 127.66 Bi-DTC 108.37 Ce-DTC 113.52 Ni-DTC 61.23 Zn-DTC 56.39 Mn-DTC 65.28

[0067] From Table 1, it can be seen that the two-dimensional network formed by the coordination of dithiocarbamate and metal has a higher specific surface area than the one-dimensional long-chain polymer, which indicates that the structure of the two-dimensional network effectively improves the specific surface area of the material, so that more active sites can be exposed, effectively improving the activity of the material, and also improving the compatibility with the hydrogel interface.

[0068] ​​​​​It can be proved that the metal ions selected in embodiments 2-4 are successfully coordinated. The obtained material has a highly ordered two-dimensional network structure, in which the metal ions and the ammonium dithiocarbamate ligands are arranged in a specific geometric manner through coordination, ultimately forming a layered network architecture. The geometric shape of the layered network architecture is not limited to a single type, and can specifically include but is not limited to square, hexagonal, octagonal and other regular geometric shapes, and can be adjusted to the target geometric structure according to actual preparation requirements.

[0069] In addition, the metal ion used in the complex of the present application is a trivalent metal ion, which has a strong charge density. The strong charge density can keep the charge distribution of the complex uniform, thereby imparting the complex strong chemical stability. Within the two-dimensional network structure, the adjacent trivalent metal ions can produce a synergistic interaction; this interaction can further enhance the mechanical strength of the complex material and simultaneously improve the structural stability of the material, avoiding structural damage or performance degradation of the material during use.

[0070] Since the present complex is a two-dimensional network structure, its structural morphology determines that the material has a large specific surface area; the large specific surface area allows the material surface to form more surface sites. The surface sites can act as reaction interfaces and active sites, and when used in vivo, can increase the contact probability of the material and biomolecules, improve the reaction efficiency, and thus effectively improve the biological activity of the complex in vivo.

[0071] Preparation of dithioformate-metal coordination two-dimensional network material doped hydrogel

[0072] Polyvinyl alcohol (PVA, molecular weight 145 kDa) and polyvinylpyrrolidone (PVP, molecular weight 58 kDa) were dissolved in deionized water at a mass ratio of 110:1 to prepare a PVA / PVP mixed solution with a concentration of 14.4 wt%, and autoclaved at 121℃ for 30 minutes and cooled to 75±5℃ for standby; DTC, Fe-DTC, Bi-DTC, and Ce-DTC were added to the PVA / PVP solution at a proportion of 0.1 wt% respectively, and mechanically stirred for 30 minutes to obtain a mixed solution; thereafter, polyethylene glycol diglycidyl ether (PEG-DGE, molecular weight 526 Da) was added to the mixed solution, accounting for 10% of the total mass of the mixed solution, and 0.3 wt% of glycerol was added, and 10M sodium hydroxide solution (100 μL / 75 g of mixed solution) was added as a catalyst, and stirred at 70℃ for 10 minutes, and then reacted at 70℃ for 12 hours; after the reaction was completed, the product was placed in a dialysis bag (molecular weight cut-off 3500 Da) and purified with 0.65 MPa polyethylene glycol (PEG, molecular weight 20 kDa) at 37℃ for 7 days to remove unreacted impurities, and then autoclaved at 121℃ for 30 minutes, and after cooling, injected into a mold, and formed at 25℃ to obtain a metal coordination two-dimensional network material doped hydrogel.

[0073] As Figure 15 shown in the complex material system involved in the present application, compared with the one-dimensional polymer long chain structure formed by the coordination of dithiocarbamate and metal ions, the two-dimensional network structure adopted in the present application has the characteristics of high specific surface area, which can form a more optimal interfacial bonding effect with the hydrogel matrix, specifically, the two-dimensional network structure can realize a more uniform dispersion state in the hydrogel matrix, effectively avoiding the agglomeration phenomenon of the one-dimensional polymer long chain, thereby improving the structural uniformity and performance stability of the composite hydrogel as a whole.

[0074] As Figure 16 shown, the metal coordination two-dimensional network material doped gel prepared by the present application is in a flow state at 70℃, and forms a gel at 37℃. It satisfies the requirements of being injectable at 70℃ and maintaining solidification at 37℃ to replace the defective nucleus pulposus.

[0075] Example 6 Mechanical property test of metal coordination two-dimensional network material doped hydrogel

[0076] (1) The rheological properties of the hydrogel samples were studied using a rheometer (Anton Paar GmbH, Austria) with a 25 mm diameter circular parallel plate clamp: The hydrogel was evenly placed on the sample table, the clamp was pressed down to a gap of 1 mm, and the excess sample was scraped to form a regular disc-shaped sample with a diameter of 25 mm and a thickness of 1 mm; all tests were performed in oscillation mode with a controlled strain amplitude of 1%, a frequency of 1 Hz, and a temperature scan from 25°C to 70°C at a rate of 15°C / min, with 1 data point collected every 0.2 min (a total of 15 valid data points), and each group of experiments was independently repeated 3 times to ensure the reliability of the results.

[0077] The dynamic viscoelasticity test results of the blank gel control group (Ctrl), ligand-doped gel group (DTC), and three metal-ligand two-dimensional network material-doped hydrogel groups (Bi-DTC, Ce-DTC, Fe-DTC) showed that (Fig. 18): Figure 17 ): The storage modulus G´ (characterizing elastic response, higher value closer to solid behavior) of all samples showed a downward trend with increasing temperature, indicating that the increase in temperature intensified the molecular motion within the material, reducing the rigidity of the network structure and gradually softening the material; among them, the G´ of the control group was the lowest, indicating that it did not form a stable and dense cross-linked network, and the elastic performance was poor; the G´ of the Bi-DTC, Ce-DTC, and Fe-DTC groups was significantly higher than that of the control group and the DTC group, confirming that the metal ions (Bi 3+ , Ce 3+ , Fe 3+ ) could act as cross-linking centers and coordinate with the functional groups of the gel matrix, increasing the cross-linking density and constructing a three-dimensional network structure with better mechanical properties, and this difference was statistically significant.

[0078] (2) The loss modulus G´´ (characterizing viscous response, higher value more energy dissipation) test results showed (Fig. 18): The G´´ of all samples showed a downward trend with increasing temperature, but the downward amplitude was smaller than that of G´, indicating that the effect of temperature on viscous response was weaker than that on elastic response; the G´´ of the Bi-DTC, Ce-DTC, and Fe-DTC groups was generally higher than that of the control group and the DTC group, which was due to the dynamic coordination between metal ions and the gel matrix - the coordination bond reversibly breaks and reforms under stress deformation, producing additional internal friction and increasing energy dissipation, enabling the material to have good energy absorption capacity.

[0079] (3) The loss factor tanδ (tanδ=G´´ / G´, measuring viscoelastic balance, tanδ>1 with mainly viscous, tanδ<1 with mainly elastic) test results showed (Fig. 18): Figure 19): The tan delta of the four groups except the Bi-DTC group was less than 1 in the whole test temperature range, indicating that the elastic behavior was dominant and had good elastic recovery ability. The tan delta of the control group was the highest, indicating that the proportion of viscous components was high, which confirmed that the network structure was loose and the strength was weak (loose structure is difficult to constrain molecular chain movement, which aggravates intermolecular friction); the tan delta of the Bi-DTC, Ce-DTC and Fe-DTC groups was lower than that of the control group and the DTC group, indicating that the metal-coordinated two-dimensional network material doping not only improved the elasticity (G' increased), but also optimized the viscoelastic balance, increased the proportion of elasticity, and made the cross-linked network more stable.

[0080] (4) The complex viscosity |η*| (characterizing the flow resistance and reflecting the viscosity and processing performance) test results show that ( Figure 20 ): The |η*| of all samples showed a slow downward trend with the increase of temperature, which was consistent with the typical viscosity characteristics of hydrogel - the increase of temperature intensified the molecular thermal motion, weakened the intermolecular force, and reduced the resistance of gel network to molecular flow; this characteristic indicated that the gel material of the application had good temperature sensitivity, and the viscosity and processing performance could be adjusted by adjusting the temperature, which provided convenience for subsequent molding processing and practical application.

[0081] Example 7 Oxygen production test of different materials

[0082] Take 18 mL of ultrapure water into a 50 mL centrifuge tube, and remove the dissolved oxygen in the water by N2 for 30 min. After the electrode of the oxygen dissolving instrument (Lei magnet JPSJ-605F) is calibrated, it is placed in the ultrapure water with air removed, and a data is measured for 10 s. After testing for 50 times, 1 mL of H2O2 (1M) is added, and a data is measured for 10 s. After testing for 50 times, 50 mL of material (1 mg / mL) is added to the above solution, and a data is measured for 10 s, and 50 groups of data are measured. The materials used in this example are the materials prepared in Examples 1-4 and Comparative Examples 1-3.

[0083] Figure 13 For oxygen production test of different materials, when there is only H2O2 in the solution, there is no obvious fluctuation of O2 content, and after adding DTC, there is no obvious O2 production, and after adding M-DTC, obvious O2 signal begins to be produced, and the O2 content gradually increases with time. Among them, the O2 production of the Ce-DTC system is the highest, and the O2 production rate of the divalent metal (Ni, Zn, Mn) coordinated polymer is obviously lower than that of Ce-DTC and Bi-DTC. This shows that the trivalent metal-coordinated two-dimensional network can effectively convert active oxygen into O2, which helps to reduce the oxidative stress caused by ROS and reduce the inflammatory response.

[0084] Example 8 Photocatalytic antibacterial experiment of four kinds of materials on 5×10 5 CFU / mL concentration of staphylococcus aureus

[0085] (1) Take 0.1 mL of the revived Staphylococcus aureus bacterial solution and measure the transmittance (OD) at a wavelength of 600 nm. 600 =1), resulting in a bacterial concentration of 5×10⁻⁶. 7 CFU / mL.

[0086] (2) Weigh the antibacterial material and add it to sterile PBS solution to prepare a suspension of 1 mg / mL.

[0087] (3) Use sterile 24-well plates and perform three parallel experiments for each concentration of material to eliminate errors. For the 10 μg / mL concentration experimental group, first add 0.98 mL of PBS solution to each well, then add 0.01 mL of material suspension, and finally add 0.01 mL of 5×10⁻⁶ PBS solution. 7 Prepare bacterial suspension at CFU / mL. Ensure the total liquid volume in each well is 1 mL. At this point, the bacterial count in each well is 5 × 10⁻⁶. 5 Each control group consisted of bacterial suspensions of the same concentration without the addition of this antibacterial material.

[0088] (4) Use a wavelength of 405 nm and an optical power of 50 mW / cm. 2 An ultraviolet lamp was placed on a well plate and irradiated for 30 minutes. Both the material group and the control group received the light. After irradiation, the well plate was inverted and placed in a 37°C incubator with air atmosphere to co-culture the bacteria and antibacterial material for 24 hours.

[0089] (5) Remove the well plate after co-culture. Aspirate the bacterial culture from the well plate and dilute it to a bacterial concentration of approximately 10. 5 Prepare a bacterial suspension at CFU / mL. Take 10 μL of the suspension from the test tube and drop it onto LB agar in a petri dish, spreading it evenly with a spreader. Then invert the petri dish and place it in a 37 °C incubator with ambient air, allowing the bacteria to grow for 24 hours.

[0090] (6) Take out the petri dish, take a picture of the growth of the colonies, count the number of colonies, and calculate the sterilization rate.

[0091] Figure 14 The optical power of 10 μg / mL DTC, Fe-DTC, Bi-DTC, and Ce-DTC at a wavelength of 405 nm is 50 mW / cm². 2 30 minutes of UV irradiation on 5×10 5 Antibacterial properties of CFU / mL Staphylococcus aureus.

[0092] Example 9: X-ray X-ray DR test of isolated sheep intervertebral disc nucleus pulposus injected with hydrogel using metal-coordinated two-dimensional network material (M-DTC).

[0093] The sheep intervertebral disc (commercial product) that completes the hydrogel injection was taken out from the storage environment (4℃ physiological saline), the surface residual liquid was gently wiped with sterile gauze to avoid moisture interference X-ray penetration and image clarity. The marker (such as metal number plate) that is not easy to be penetrated by X-ray was used to mark the non-key area (such as the edge of the annulus fibrosus) of the intervertebral disc sample, and the sample number, hydrogel injection dose and injection time were recorded to facilitate the correspondence of the subsequent image and sample information. The marked intervertebral disc was placed on the sample fixing frame of the X-DR imaging table, the posture of the intervertebral disc was adjusted, the nucleus pulposus injection area (i.e. the hydrogel distribution area) was in a horizontal state, and was parallel to the imaging table plane, to ensure that the shooting area was not tilted or deviated. The flow chart is shown in Figure 2 .

[0094] Figure 21 The X-ray X-DR image of the sheep intervertebral disc after injecting hydrogel into the nucleus pulposus (from left to right: blank gel, Ce-DTC, Bi-DTC, DTC, Fe-DTC), tube voltage 75 kV, as can be seen from the figure, between the end faces of the two vertebral bodies is the intervertebral disc nucleus pulposus, containing Ce-DTC, Bi-DTC, Fe-DTC hydrogel has good developing effect after injection, which can effectively show the injection and filling effect of the hydrogel, and the hydrogel containing only DTC is effectively filled, but the developing effect is not obvious.

Claims

1. A method for preparing a dithioformate-metal coordination two-dimensional network material, characterized in that, Comprising the following steps, Step 1, take p-phenylenediamine and dissolve it in slightly hot water at 30-40℃ until it is fully dissolved, then add ammonia water and carbon disulfide in sequence, and the molar ratio of p-phenylenediamine to carbon disulfide is 1:2, react for 2-3 hours below 20℃, then filter and wash with anhydrous ethanol and ether in sequence, and vacuum dry at 40℃ for 12 hours to obtain p-phenylenediamine bis thiocarbamic acid ammonium salt; Step 2, dissolve the p-phenylenediamine bis thiocarbamic acid ammonium salt and metal salt in anhydrous ethanol respectively, then mix the two solutions uniformly, and the molar ratio of p-phenylenediamine bis thiocarbamic acid ammonium salt to metal salt is 3:2, reflux at 80℃ for 0.5 hours, then wash with water and ethanol respectively, and vacuum dry at 60℃ for 12 hours to obtain a kind of bis thiocarbamate-metal coordination two-dimensional network material, denoted as M-DTC; wherein the metal salt is bismuth nitrate, cerium chloride, bismuth chloride, cerium sulfate or ferric chloride.

2. A class of dithioformate-metal coordination two-dimensional network materials prepared based on the method of any one of claim 1, characterized in that, The kind of bis thiocarbamate-metal coordination two-dimensional network material has a highly ordered two-dimensional network structure.

3. A composite hydrogel with antibacterial, anti-inflammatory, and imaging functions, characterized in that, The bis thiocarbamate-metal coordination two-dimensional network material of claim 2.

4. The method for preparing the composite hydrogel with anti-bacterial and anti-inflammatory imaging functions according to claim 3, characterized in that, The preparation method is to dissolve polyvinyl alcohol and polyvinylpyrrolidone in deionized water at a mass ratio of 110:1 to prepare a polyvinyl alcohol / polyvinylpyrrolidone mixed solution with a concentration of 12.6-20.0wt%, sterilize at 121℃ and 26KPa for 30 minutes, cool to 75±5℃ for standby, add the bis thiocarbamate-metal coordination two-dimensional network material to the polyvinyl alcohol / polyvinylpyrrolidone mixed solution at a proportion of 0.1wt%, and mechanically stir thoroughly, then add polyethylene glycol diglycidyl ether, which accounts for 8-15% of the total mass of the mixed solution, then add 0.3wt% glycerol, and then add 10M sodium hydroxide solution as a catalyst, stir at 70℃ for 10 minutes, then react at 60-70℃ for 10-20 hours, then place the product in a dialysis bag, purify with 0.65MPa polyethylene glycol permeate solution at 37℃ for 7 days to remove unreacted impurities, then sterilize at 121℃ and 26KPa for 30 minutes, cool and pour into a mold, and form at 25℃ to obtain a metal coordination two-dimensional network material doped hydrogel.

5. The preparation method of the anti-bacterial and anti-inflammatory imaging function according to claim 4, characterized in that, The molecular weight of polyvinyl alcohol is 145kDa, the molecular weight of polyvinylpyrrolidone is 58kDa, the molecular weight of polyethylene glycol diglycidyl ether is 526Da, the molecular weight cut-off of the dialysis bag is 3500Da, and the molecular weight of polyethylene glycol is 20kDa.

6. Use of the kind of bis thiocarbamate-metal coordination two-dimensional network material of claim 2 or the composite hydrogel with antibacterial and anti-inflammatory imaging functions of claim 3 in the preparation of a drug for treating intervertebral disc nucleus degenerative disease.

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