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

Abstract

The invention discloses a dithioformate-metal coordination two-dimensional network material, composite hydrogel and application thereof, and belongs to the field of biomedical materials. The preparation method comprises the following steps: preparing ammonium p-phenylenediamine dithiocarbamate (DTC) by taking p-phenylenediamine and carbon disulfide as raw materials, water as a solvent and ammonia water as a catalyst; and reacting the trivalent metal salt with DTC to form a two-dimensional network material. The two-dimensional network material is doped into the chemical cross-linked polyvinyl alcohol / polyethylene glycol hydrogel, and the composite hydrogel has excellent mechanical properties, good antibacterial performance and the effects of scavenging free radicals and relieving inflammation. Experiments prove that the hydrogel is used for tissues with the intervertebral disc nucleus pulposus degeneration, has good development and can effectively display the injection and filling effects of the hydrogel, and a new direction is provided for treatment of the intervertebral disc nucleus pulposus degeneration.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials, specifically relating to a class of dithiocarbamate-metal coordination two-dimensional network materials, composite hydrogels and their applications. Background Technology

[0002] Degenerative changes in the nucleus pulposus of the intervertebral disc are one of the main causes of low back pain (Advances in Clinical Medicine, 2020, 10(10): 2302-2310). Its pathological features include dehydration of the nucleus pulposus tissue, loss of proteoglycans, and disordered collagen fiber structure, accompanied by the massive release of inflammatory factors (such as IL-1β and TNF-α) and macrophage infiltration, which ultimately leads to a decrease in intervertebral disc height and loss of mechanical function, seriously affecting the patient's quality of life.

[0003] Current clinical treatments have significant limitations: conservative treatments (such as anti-inflammatory drugs and physical therapy) can only relieve symptoms and cannot stop disease progression; surgical treatments (such as discectomy and spinal fusion) can relieve nerve compression, but carry risks such as postoperative degeneration of adjacent segments and loss of spinal mobility; patent CN202510054848.0 reports a composite hydrogel of animal glue, polyvinyl alcohol, glycerin, and water, which has rheological and mechanical properties similar to natural nucleus pulposus and also possesses tissue adhesion, but animal glue is prone to causing immune reactions. Patents such as CN20221121835.0 report independently packaged crosslinking agents and hydrogel precursor solutions. When a crosslinking agent is added to the hydrogel precursor solution, a hydrogel can be rapidly formed under mild conditions. This repair product can be instantly formed in vivo upon injection, but due to the use of hydrogel polymer precursor solutions, it has a certain degree of toxicity, and the crosslinking formed by metal ion coordination will degrade with long-term use. An ideal hydrogel formulation for nucleus pulposus filling should possess mechanical properties matching those of the natural nucleus pulposus, variable flowability to ensure smooth injection, certain antibacterial, anti-inflammatory, and tissue repair activities, be free of toxic small molecules, have high stability, and be radiolucent for easy observation of injection molding performance. Based on these standards, no relevant patents or products have been reported in China to date.

[0004] Metal-coordinated two-dimensional network materials, with their unique structure (J. Am. Chem. Soc. 2021, 143, 37; Chemical Engineering Journal, 2024, 488, 150945), possess excellent chemical stability and bioactivity, and can achieve anti-inflammatory, antibacterial, and imaging functions by regulating ion release. Polyvinyl alcohol (PVA), polyvinylpyrrolidone, and polyethylene glycol diglycidyl ether are biomaterials approved for use by the US FDA (Adv. Mater. 2024, 36, 2306326). The hydrogel structure and mechanical properties prepared from these materials are highly similar to natural nucleus pulposus tissue, making them ideal nucleus pulposus replacement carriers. Combining metal-coordinated two-dimensional network materials with hydrogels holds promise for preparing novel nucleus pulposus repair materials with multiple functions including mechanical support, antibacterial, anti-inflammatory repair, and imaging, providing a new strategy for the treatment of degenerative disc herniation. However, existing nucleus pulposus replacement materials (such as simple polyvinyl alcohol hydrogels and collagen scaffolds) have poor mechanical properties that match the natural nucleus pulposus and lack anti-inflammatory and tissue repair activities, making it difficult to achieve long-term therapeutic effects. At the same time, these materials often have small specific surface areas and small active sites, making it difficult to efficiently composite hydrogels, and they lack precise functional design for the microenvironment of nucleus pulposus lesions, which makes it difficult to meet clinical treatment needs. Summary of the Invention

[0005] To address the shortcomings of existing treatments for degenerative disc disease, this invention provides a type of dithiocarbamate-metal coordination two-dimensional network material, a composite hydrogel, and their applications. This type of dithiocarbamate-metal coordination two-dimensional network material exhibits good bactericidal and anti-inflammatory effects against Escherichia coli or Staphylococcus aureus. The composite hydrogel prepared using it achieves a unified approach of mechanical support, anti-inflammatory repair, and imaging, and is expected to effectively delay or even reverse the progression of degenerative disc disease, showing promising application prospects.

[0006] To overcome the shortcomings of existing technologies, the technical solution adopted by this invention is as follows:

[0007] A method for preparing a class of dithiocarbamate-metal coordination two-dimensional network materials includes the following steps:

[0008] Step 1: Dissolve p-phenylenediamine in a hot water solution at 30-40℃ until fully dissolved, then add ammonia and carbon disulfide in sequence, with a molar ratio of p-phenylenediamine to carbon disulfide of 1:2. React at below 20℃ for 2-3 hours, filter, wash with anhydrous ethanol and diethyl ether in sequence, and dry under vacuum at 40℃ for 12 hours to obtain p-phenylenediamine dithiocarbamate ammonium.

[0009] Step 2: Dissolve p-phenylenediamine dithiocarbamate and the metal salt separately in anhydrous ethanol, then mix the two solutions thoroughly. The molar ratio of p-phenylenediamine dithiocarbamate to the metal salt is 3:2. Reflux the mixture at 80°C for 0.5 hours. After washing with water and ethanol respectively, dry the mixture under vacuum at 60°C for 12 hours to obtain a type of dithiocarbamate-metal coordination two-dimensional network material, denoted as M-DTC.

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

[0011] The dithiocarbamate-metal coordination two-dimensional network materials prepared by any of the above methods have a highly ordered two-dimensional network structure.

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

[0013] The preparation method of the above-mentioned composite hydrogel with antibacterial, anti-inflammatory and imaging functions involves 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%. The solution is sterilized at 121℃ and 26KPa for 30 minutes and then cooled to 75±5℃ for later use. A dithiocarbamate-metal coordination two-dimensional network material is added to the polyvinyl alcohol / polyvinylpyrrolidone mixed solution at a ratio of 0.1wt%, and mechanically stirred thoroughly. Polyethylene glycol diglycidyl ether is then added, with the ether accounting for 8-15% of the total mass of the mixture. Finally, 0.3wt% glycerol is added. Then, 10M sodium hydroxide solution was added as a catalyst. After stirring at 70°C for 10 minutes, the mixture was reacted at 60-70°C for 10-20 hours. The product was then placed in a dialysis bag and purified with 0.65MPa polyethylene glycol permeation solution at 37°C for 7 days to remove unreacted impurities. Subsequently, it was sterilized at 121°C and 26KPa for 30 minutes. After cooling, it was injected into a mold and molded at 25°C to obtain a hydrogel doped with metal-coordinated two-dimensional network material.

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

[0015] The application of the above-mentioned dithiocarbamate-metal coordination two-dimensional network materials or the above-mentioned composite hydrogels with antibacterial, anti-inflammatory and imaging functions in the preparation of drugs for treating intervertebral disc nucleus pulposus degeneration.

[0016] Beneficial effects:

[0017] This invention relates to a class of dithiocarbamate-metal coordination two-dimensional network materials, composite hydrogels, and their applications. The coordination two-dimensional network material is obtained by reacting ammonium dithiocarbamate with a trivalent metal salt. Compared with one-dimensional polymer chains prepared from divalent metal salts (NiCl2, ZnCl2, MnCl2), it has advantages such as a loose and porous structure and ease of preparation. It can effectively expose active sites, efficiently convert reactive oxygen species (ROS) into oxygen, reduce ROS, thereby reducing local inflammatory responses and alleviating local oxidative stress. It has the following advantages:

[0018] (1) This invention obtains a coordinated two-dimensional network material through the reaction of ammonium dithiocarbamate and trivalent metal salts, which improves the antioxidant effect of ammonium dithiocarbamate itself. The specified metal salts all have their own advantages. For example, iron promotes the activity of related enzymes in the body, regulates redox reactions, and combats oxidative stress. After iron ions coordinate with ammonium carbamate compounds, they may enhance antioxidant capacity, thereby slowing down the degenerative changes of the intervertebral disc. Bismuth ions have strong anti-inflammatory effects and have potential effects on tissue repair and regeneration. After bismuth ions coordinate with ammonium carbamate compounds, they may reduce degenerative damage by inhibiting the release of inflammatory factors in the intervertebral disc and promoting cell repair. Cerium ions have antioxidant properties and can scavenge free radicals in the body, reducing cell damage caused by oxidative stress. In addition, cerium can also promote the activity of some enzymes in the body and improve cell repair and regeneration.

[0019] (2) The two-dimensional network structure of the dithiocarbamate-metal coordination two-dimensional network material of the present invention provides more surface active sites, and metal ions can better bind to receptors on the bacterial surface or interfere with bacterial metabolic processes. This helps to improve the ROS scavenging capacity of the material, reduce inflammation-related oxidative damage, and inhibit the occurrence and development of inflammation. At the same time, the ion release effect of the metal coordination two-dimensional network material is utilized to achieve anti-inflammatory and tissue repair functions.

[0020] (3) The structure of the metal coordination two-dimensional network material of the present invention 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 work together to improve the material performance. During the preparation process, the mechanical properties of the hydrogel are matched with those of the natural nucleus pulposus by adjusting the concentration of PVA / PVP, the degree of crosslinking of PEG-DGE and the amount of metal coordination two-dimensional network material. Attached Figure Description

[0021] Figure 1 This is a synthetic route diagram for a class of dithiocarbamate-metal coordination two-dimensional network materials of the present invention;

[0022] Figure 2This is a flowchart illustrating the treatment of degenerative lesions of the nucleus pulposus using a composite hydrogel doped with a dithiocarbamate-metal coordination two-dimensional network material, as described in this invention.

[0023] Figure 3 XRD patterns of dithiocarbamate-metal coordination two-dimensional network materials prepared for different metal salts;

[0024] Figure 4 Infrared spectra of dithiocarbamate-metal coordination two-dimensional network materials prepared for different metal salts;

[0025] Figure 5 NMR of p-phenylenediamine dithiocarbamate (DTC) prepared in this invention 13 C spectrum;

[0026] Figure 6 The dithiocarbamate-Fe prepared in this invention 3+ NMR of coordination two-dimensional network material (Fe-DTC) 13 C spectrum;

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

[0028] Figure 8 The dithiocarbamate-Ce prepared according to the present invention 3+ NMR of coordinated two-dimensional network material (Ce-DTC) 13 C spectrum;

[0029] Figure 9 Scanning electron microscope images and elemental distribution maps of DTC prepared in this invention;

[0030] Figure 10 Scanning electron microscope images and elemental distribution maps of Fe-DTC prepared in this invention;

[0031] Figure 11 Scanning electron microscope images and elemental distribution maps of Bi-DTC prepared in this invention;

[0032] Figure 12 Scanning electron microscope images and elemental distribution maps of Ce-DTC prepared in this invention;

[0033] Figure 13 A graph showing the oxygen production test records for different materials;

[0034] Figure 14 The antibacterial test results are for the dithiocarbamate-metal coordination two-dimensional network material prepared in this invention.

[0035] Figure 15 Physical images of dithiocarbamate-metal coordination two-dimensional network materials prepared for different metal salts incorporated into hydrogels;

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

[0037] Figure 17 Elastic response diagrams of hydrogels doped with dithiocarbamate-metal coordination two-dimensional network materials prepared for different metal salts;

[0038] Figure 18 Viscosity response diagram of hydrogels doped with dithiocarbamate-metal coordination two-dimensional network materials prepared for different metal salts;

[0039] Figure 19 Viscoelasticity tests of hydrogels doped with dithiocarbamate-metal coordination two-dimensional network materials prepared for different metal salts;

[0040] Figure 20 Complex viscosity tests were conducted on hydrogels doped with five different samples.

[0041] Figure 21 X-ray X-ray image after injecting hydrogel into the nucleus pulposus of an isolated sheep intervertebral disc. Detailed Implementation

[0042] The raw materials used in this invention are all existing products, and the specific preparation methods and performance testing are conventional techniques.

[0043] The pressure used for high-pressure sterilization in this invention is 26 kPa.

[0044] This invention involves reacting p-phenylenediamine with carbon disulfide in an alkaline solution to obtain the p-phenylenediamine dithiocarbamate ammonium ligand; then reacting a metal salt with the p-phenylenediamine dithiocarbamate ammonium ligand material in an aqueous solution to obtain the metal-coordinated dithiocarbamate derivative. The synthetic steps are as follows: Figure 1 As shown.

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

[0046] 5.4 g of p-phenylenediamine was dissolved in 10 mL of 35°C hot water, followed by the addition of 18 mL of 25% ammonia and 6 mL of carbon disulfide. The mixture was stirred at 0°C for 3 h. After the reaction was completed, the mixture was filtered and washed with ethanol and diethyl ether, respectively. Finally, the obtained solid product was dried in a vacuum drying oven at 40°C for 12 h to obtain ammonium dithiocarbamate (DTC).

[0047] Example 2 Dithiocarbamate-Fe3+ Synthesis of Coordination Two-Dimensional Network Material (Fe-DTC)

[0048] DTC and FeCl3 were dissolved separately in equal volumes of anhydrous ethanol at a molar ratio of 3:2. The FeCl3 ethanol solution was then slowly added dropwise to the DTC ethanol solution. The mixture was refluxed at 80°C for 0.5 h. After the reaction was complete, the mixture was filtered and washed with water and ethanol, respectively. The resulting solid product was dried under vacuum at 60°C for 12 h to obtain Fe-DTC.

[0049] Example 3: Bi-dithiocarbamate 3+ Synthesis of Coordination Two-Dimensional Network Materials (Bi-DTC)

[0050] DTC and BiCl3 were dissolved separately in equal volumes of anhydrous ethanol at a molar ratio of 3:2. Then, the aqueous solution of BiCl3 was slowly added dropwise to the ethanol solution of DTC. The mixture was refluxed at 80°C for 0.5 h. After the reaction was complete, the mixture was filtered and washed with water and ethanol, respectively. The resulting solid product was dried under vacuum at 60°C for 12 h to obtain the product Bi-DTC.

[0051] Example 4 Dithiocarbamate-Ce 3+ Synthesis of Coordination Two-Dimensional Network Material (Ce-DTC)

[0052] DTC and CeCl3 were dissolved separately in equal volumes of anhydrous ethanol at a molar ratio of 3:2. Then, CeCl3 was... 3+ An ethanol solution was slowly added dropwise to an ethanol solution of DTC. The mixture was refluxed at 80°C for 0.5 h. After the reaction was complete, the mixture was filtered, washed with water and ethanol respectively, and the resulting solid product was dried under vacuum at 60°C for 12 h to obtain Ce-DTC.

[0053] Comparative Example 1

[0054] Except for replacing ferric chloride with NiCl2 in Example 2, the other operations are the same, and a long chain of metal-coordinated dithiocarbamate polymer is obtained, denoted as Ni-DTC.

[0055] Comparative Example 2

[0056] Except for replacing ferric chloride with ZnCl2 in Example 2, the other operations are the same, and a long chain of metal-coordinated dithiocarbamate polymer is obtained, denoted as Zn-DTC.

[0057] Comparative Example 3

[0058] Except for replacing ferric chloride with MnCl2 in Example 2, the other operations are the same, and a long chain of metal-coordinated dithiocarbamate polymer is obtained, denoted as Mn-DTC.

[0059] The materials prepared in Examples 1-4 and Comparative Examples 1-3 were tested, and the results are as follows: Figure 3-12 As shown in Table 1.

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

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

[0062] Figure 5 MRI of DTC 13 C spectrum; Figure 6 NMR of Fe-DTC 13 C spectrum; Figure 7 NMR of Bi-DTC 13 C spectrum; Figure 8 NMR of Ce-DTC 13 C-spectrum. From NMR. 13 The C-ray spectrum shows that C atoms in different chemical environments correspond to different peaks.

[0063] Figure 9 Scanning electron microscope images and elemental distribution maps of DTC; Figure 10 Scanning electron microscope images and elemental distribution maps of Fe-DTC; Figure 11 Scanning electron microscope images and elemental distribution maps of Bi-DTC; Figure 12 Scanning electron microscope image and elemental distribution map of Ce-DTC.

[0064] The successful synthesis of the material can be confirmed by combining XRD patterns and infrared spectroscopy. The elemental distribution diagram from SEM shows that Fe, Bi, and Ce elements are uniformly distributed in the material.

[0065] Table 1 shows the specific surface area values ​​of dithiocarbamate metal coordination two-dimensional networks and one-dimensional long-chain polymers.

[0066] Material <![CDATA[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] As can be seen from Table 1, the two-dimensional network formed by the coordination of dithiocarbamate and metal has a higher specific surface area than the one-dimensional polymer long chain. This indicates that the structure of the two-dimensional network effectively increases the specific surface area of ​​the material, allowing more active sites to be exposed, thus effectively improving the activity of the material and also enhancing its compatibility with the hydrogel interface.

[0068] This demonstrates that the metal ions selected in Examples 2-4 were successfully coordinated. The resulting material possesses a highly ordered two-dimensional network structure. In this network structure, metal ions and ammonium dithiocarbamate ligands are oriented in a specific geometric manner through coordination, ultimately forming a layered network architecture. The geometric shape of this layered network architecture is not limited to a single type; it can include, but is not limited to, various regular geometric shapes such as squares, hexagons, and octagons, and can be adjusted to the target geometric structure according to actual preparation requirements.

[0069] Furthermore, the metal ions used in the complexes of this invention are trivalent metal ions, which possess a high charge density. This high charge density enables the overall charge distribution of the complex to remain uniform, thereby endowing the complex with strong chemical stability. Within the two-dimensional network structure, adjacent trivalent metal ions can generate synergistic interactions; these interactions can further enhance the mechanical strength of the complex material and simultaneously improve its structural stability, preventing structural damage or performance degradation during use.

[0070] Because this complex has a two-dimensional network structure, its morphology determines that the material has a large specific surface area; this large specific surface area allows for the formation of more surface sites on the material surface. These surface sites can serve as reaction interfaces and active sites, increasing the probability of contact between the material and biomolecules when applied in vivo, thereby improving reaction efficiency and effectively enhancing the bioactivity of the complex in vivo.

[0071] Example 5: Preparation of dithiocarbamate-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 14.4 wt% PVA / PVP mixed solution. The solution was autoclaved at 121°C for 30 minutes and cooled to 75±5°C for later use. DTC, Fe-DTC, Bi-DTC, and Ce-DTC were added to the PVA / PVP solution at a ratio of 0.1 wt%, and the mixture was mechanically stirred for 30 minutes to obtain a mixture. Then, polyethylene glycol diglycidyl ether (PEG-DGE, molecular weight 526 Da) was added to the mixture, accounting for 10% of the total mass of the mixture. Next, 0.3 wt% glycerol was added, followed by 10 M... Sodium hydroxide solution (100 μL / 75 g mixture) was used as a catalyst. After stirring at 70 °C for 10 minutes, the mixture was reacted at 70 °C for 12 hours. After the reaction, the product was placed in a dialysis bag (molecular weight cutoff 3500 Da) and purified by permeation with polyethylene glycol (PEG, molecular weight 20 kDa) solution at 0.65 MPa at 37 °C for 7 days to remove unreacted impurities. Then, it was autoclaved at 121 °C for 30 minutes, cooled, and injected into a mold. The mixture was then molded at 25 °C to obtain a hydrogel doped with a metal-coordinated two-dimensional network material.

[0073] like Figure 15 As shown in the complex material system of this invention, 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 this invention has a high specific surface area and can form a better interfacial bonding effect with the hydrogel matrix. Specifically, the two-dimensional network structure can achieve a more uniform dispersion in the hydrogel matrix, effectively avoiding the aggregation phenomenon that is prone to occur in one-dimensional polymer long chains, thereby improving the overall structural uniformity and performance stability of the composite hydrogel.

[0074] like Figure 16 As shown, the metal-coordinated two-dimensional network material-doped gel prepared in this invention is in a fluid state at 70°C and forms a gel at 37°C. It satisfies the requirements of being injectable at 70°C and remaining solidified at 37°C to replace defective nucleus pulposus.

[0075] Example 6 Mechanical property testing of metal-coordinated two-dimensional network material-doped hydrogels

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

[0077] Dynamic viscoelasticity test results for the blank gel control group (Ctrl), the doped ligand gel group (DTC), and the three metal coordination two-dimensional network material doped hydrogel groups (Bi-DTC, Ce-DTC, Fe-DTC) showed that ( Figure 17 The storage modulus G´ (characterizing elastic response; higher values ​​indicate closer resemblance to solid behavior) of all samples decreased with increasing temperature, indicating that increased temperature intensifies molecular motion within the material, reduces network structure rigidity, and gradually softens the material. The control group had the lowest G´, indicating the lack of a stable, dense cross-linked network and poor elastic properties. The G´ values ​​of the Bi-DTC, Ce-DTC, and Fe-DTC groups were significantly higher than those of the control and DTC groups, confirming the presence of metal ions (Bi... 3+ Ce 3+ Fe 3+ It can serve as a crosslinking center to coordinate with functional groups in the gel matrix, thereby increasing the crosslinking density and constructing a three-dimensional network structure with better mechanical properties. Moreover, this difference is statistically significant.

[0078] (2) The test results of loss modulus G´´ (characterizing viscous response, the higher the value, the more energy is dissipated) show (Figure 18): the G´´ of all samples decreases with increasing temperature, but the decrease is less than that of G´, indicating that the effect of temperature on viscous response is weaker than that on elastic response; the G´´ of Bi-DTC, Ce-DTC and Fe-DTC groups are generally higher than those of the control group and DTC group, which is due to the dynamic coordination of metal ions and gel matrix - the coordination bonds can be reversibly broken and reorganized when deformed under force, generating additional internal friction, increasing energy dissipation, and giving the material good energy absorption capacity.

[0079] (3) Loss factor tanδ (tanδ=G´´ / G´, measures viscoelastic equilibrium, tanδ>1 indicates viscous dominance, tanδ<1 indicates elastic dominance) test results show ( Figure 19Throughout the entire test temperature range, except for the Bi-DTC group, the tanδ of the other four groups was less than 1, indicating that elastic behavior was dominant and that they had good elastic recovery ability. The control group had the highest tanδ, indicating that the proportion of viscous components was high, which confirmed that its network structure was loose and weak (loose structure is difficult to constrain molecular chain movement and aggravates intermolecular friction). The tanδ 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 doping of metal coordination two-dimensional network materials not only improves elasticity (G´ increases), but also optimizes the viscoelastic balance, increases the proportion of elasticity, and makes the cross-linked network more robust and stable.

[0080] (4) Complex viscosity |η*| (characterizing flow resistance, reflecting viscosity and processing performance) test results show that ( Figure 20 The |η*| of all samples showed a slow decreasing trend with increasing temperature, which is consistent with the typical viscosity characteristics of hydrogels—increased temperature intensifies molecular thermal motion, weakens intermolecular forces, and reduces the obstruction of molecular flow by the gel network. This characteristic indicates that the gel material of the present invention has good temperature sensitivity, and its viscosity and processing performance can be adjusted by controlling the temperature, which provides convenience for subsequent molding and processing and practical applications.

[0081] Example 7 Oxygen Production Test of Different Materials

[0082] Add 18 mL of ultrapure water to a 50 mL centrifuge tube and purge with N2 for 30 min to remove dissolved oxygen. After calibrating the electrodes of the dissolved oxygen analyzer (Leici JPSJ-605F), place it in the air-purified ultrapure water and measure data every 10 seconds. After 50 tests, add 1 mL of H2O2 (1M) and measure data every 10 seconds. After 50 tests, add 50 mL of the material (1 mg / mL) to the above solution and measure every 10 seconds, for a total of 50 sets of data. The materials used in this example include those prepared in Examples 1-4 and Comparative Examples 1-3.

[0083] Figure 13 For oxygen production testing of different materials, when only H2O2 was present in the solution, there was no significant fluctuation in O2 content. Adding DTC also resulted in no significant O2 production. However, the addition of M-DTC initiated a noticeable O2 signal, with the O2 content gradually increasing over time. The Ce-DTC system exhibited the highest O2 production, and the O2 yield of polymers coordinated with divalent metals (Ni, Zn, Mn) was significantly lower than that of Ce-DTC and Bi-DTC. This indicates that the two-dimensional network coordinated with trivalent metals can effectively convert reactive oxygen species into O2, helping to reduce ROS-induced oxidative stress and inflammation.

[0084] Example 8: Four materials for 5×10 5 Photocatalytic antibacterial experiment of Staphylococcus aureus at CFU / mL concentration

[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) A wavelength of 405 nm and an optical power of 50 mW / cm² were used. 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 excised sheep intervertebral discs (commercially available products) after hydrogel injection are removed from their storage environment (4°C physiological saline). Residual liquid is gently wiped from the surface with sterile gauze to prevent moisture from interfering with X-ray penetration and image clarity. Non-critical areas of the disc sample (such as the edge of the annulus fibrosus) are marked with a marker that is not easily penetrated by X-rays (such as a metal number tag). The sample number, hydrogel injection dose, and injection time are recorded for subsequent image-sample information matching. The marked disc is placed on the sample holder of the X-DR imaging table. The disc's orientation is adjusted so that the nucleus pulposus injection area (i.e., the hydrogel distribution area) is horizontal and parallel to the imaging table plane, ensuring the imaging area is not tilted or offset. The flowchart is as follows: Figure 2 As shown.

[0094] Figure 21 X-ray X-ray images (from left to right: blank gel, Ce-DTC, Bi-DTC, DTC, Fe-DTC) after injecting hydrogel into the nucleus pulposus of an isolated sheep intervertebral disc, with a tube voltage of 75 kV. As can be seen from the images, hydrogels containing Ce-DTC, Bi-DTC, and Fe-DTC showed good imaging effects after injection into the nucleus pulposus between the two vertebral bodies, effectively demonstrating the injection and filling effect of the hydrogel. Hydrogels containing only DTC showed effective filling, but the imaging effect was not obvious.

Claims

1. A method for preparing a class of dithiocarbamate-metal coordination two-dimensional network materials, characterized in that, Includes the following steps, Step 1: Dissolve p-phenylenediamine in a hot water solution at 30-40℃ until fully dissolved, then add ammonia and carbon disulfide in sequence, with a molar ratio of p-phenylenediamine to carbon disulfide of 1:

2. React at below 20℃ for 2-3 hours, filter, wash with anhydrous ethanol and diethyl ether in sequence, and dry under vacuum at 40℃ for 12 hours to obtain p-phenylenediamine dithiocarbamate ammonium. Step 2: Dissolve p-phenylenediamine dithiocarbamate and the metal salt separately in anhydrous ethanol, then mix the two solutions thoroughly. The molar ratio of p-phenylenediamine dithiocarbamate to the metal salt is 3:

2. Reflux the mixture at 80°C for 0.5 hours. After washing with water and ethanol respectively, dry the mixture under vacuum at 60°C for 12 hours to obtain a type of dithiocarbamate-metal coordination two-dimensional network material, denoted as M-DTC.

2. The method for preparing a type of dithiocarbamate-metal coordination two-dimensional network material according to claim 1, characterized in that, The metal salt mentioned in step 2 is bismuth nitrate, cerium chloride, bismuth chloride, cerium sulfate, or ferric chloride.

3. A type of dithiocarbamate-metal coordination two-dimensional network material prepared by the method according to any one of claims 1-2, characterized in that, The aforementioned dithiocarbamate-metal coordination two-dimensional network material has a highly ordered two-dimensional network structure.

4. A composite hydrogel with antibacterial, anti-inflammatory, and imaging functions, characterized in that, It comprises the dithiocarbamate-metal coordination two-dimensional network material as described in claim 3.

5. A method for preparing a composite hydrogel with antibacterial, anti-inflammatory, and imaging functions according to claim 4, characterized in that, The preparation method involves dissolving polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) in deionized water at a mass ratio of 110:1 to prepare a PVA / PVP mixed solution with a concentration of 12.6~20.0 wt%. The solution is then sterilized at 121℃ and 26 kPa for 30 minutes and cooled to 75±5℃ for later use. A dithiocarbamate-metal coordination two-dimensional network material is added to the PVA / PVP mixed solution at a ratio of 0.1 wt%, and mechanically stirred thoroughly. Polyethylene glycol diglycidyl ether is then added, with the ether accounting for 8~15% of the total mass of the mixture. 0.3 wt% glycerol is then added, followed by 10 M... Sodium hydroxide solution was used as a catalyst. After stirring at 70°C for 10 minutes, the mixture was reacted at 60-70°C for 10-20 hours. The product was then placed in a dialysis bag and purified with polyethylene glycol permeation solution at 0.65 MPa at 37°C for 7 days to remove unreacted impurities. Subsequently, it was sterilized at 121°C and 26 kPa for 30 minutes. After cooling, the product was injected into a mold and molded at 25°C to obtain a hydrogel doped with a metal-coordinated two-dimensional network material.

6. The preparation method with antibacterial, anti-inflammatory, and imaging functions according to claim 5, characterized in that, The molecular weight of polyvinyl alcohol is 145 kDa, the molecular weight of polyvinylpyrrolidone is 58 kDa, the molecular weight of polyethylene glycol diglycidyl ether is 526 Da, the molecular weight cutoff of the dialysis bag is 3500 Da, and the molecular weight of polyethylene glycol is 20 kDa.

7. The application of the dithiocarbamate-metal coordination two-dimensional network material according to claim 3 or the composite hydrogel with antibacterial, anti-inflammatory and imaging functions according to claim 4 in the preparation of drugs for treating degenerative disc herniation.

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