Photoresponse multifunctional nano composite hydrogel as well as preparation method and application thereof

Abstract

The invention discloses light-response multifunctional nano-composite hydrogel as well as a preparation method and application thereof, belongs to the technical field of biomedical materials, and aims to solve the technical problems that an existing wound dressing is single in function and difficult to meet complex clinical requirements (such as stable wound covering, exudate management, efficient antibacterial and healing-promoting synergistic effects). The PGC-ZnO nano composite hydrogel is constructed by introducing zinc oxide nano particles into a polyacrylamide / gelatin / carboxymethyl chitosan composite network. The multi-level crosslinking effect (covalent main chain, coordination network and physical entanglement) of the composite network is utilized to improve the mechanical property and stability of the hydrogel, the synergistic effect of ZnO NPs and near-infrared light is utilized to realize efficient antibiosis, and meanwhile, the wound microenvironment is synergistically regulated and controlled through the components, so that the wound healing effect is improved. And finally, the hydrogel is endowed with excellent wound surface adaptability, exudate management capability, antibacterial activity and healing promotion performance, and a multifunctional dressing solution is provided for clinical complex wound surface treatment.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, and more specifically, to a photoresponsive multifunctional nanocomposite hydrogel, its preparation method and application, which is particularly suitable for clinical wound care scenarios requiring stable coverage, efficient antibacterial properties and healing promotion. Background Technology

[0002] As the body's largest defense organ, the skin plays a crucial role in maintaining fluid balance, sensing external stimuli, regulating body temperature, and resisting pathogen invasion. However, the skin is susceptible to mechanical damage, burns, scalds, and other external factors that can cause wounds. If not properly treated or if healing is delayed, complications such as bleeding, infection, and tissue necrosis may occur, and in severe cases, even threaten the patient's life.

[0003] Wound healing is a complex physiological process, encompassing three overlapping phases: the hemostatic and inflammatory phase, the proliferative and re-epithelialization phase, and the tissue remodeling phase. Traditional wound dressings, such as gauze and ordinary hydrogels, only provide physical coverage and cannot meet the multiple needs of wound healing, including antibacterial properties, exudate absorption, and promotion of tissue repair. Although various hydrogel dressings have been developed in existing technologies, natural polymer-based hydrogels suffer from insufficient mechanical stability, while synthetic polymer-based hydrogels exhibit poor bioactivity. Furthermore, single-function hydrogels are ill-suited to address the complex pathological microenvironment of wounds, such as persistent inflammation, drug-resistant bacterial infections, and insufficient angiogenesis.

[0004] Photothermal therapy (PTT), as a novel antibacterial technology, offers advantages such as rapid and efficient treatment with low rates of drug resistance. Combining PTT with hydrogels can endow dressings with photoresponsive antibacterial properties. Zinc oxide nanoparticles (ZnO NPs) possess broad-spectrum antibacterial activity and can release Zn... 2+ It promotes tissue repair, but simple physical blending can easily lead to Zn... 2+ Sudden drug release can affect long-term treatment outcomes. Therefore, developing a multifunctional hydrogel dressing that combines excellent mechanical properties, controllable drug release, highly efficient photothermal antibacterial properties, and healing-promoting functions is of great significance for solving clinical wound treatment challenges. Summary of the Invention

[0005] To address the technical problems of existing wound dressings, such as limited functionality, easy aggregation / burst release of nano-antibacterial components, and difficulty in adapting to the needs of the wound microenvironment, this invention innovatively combines zinc oxide nanoparticles (ZnO NPs) with a polyacrylamide / gelatin / carboxymethyl chitosan composite hydrogel. By constructing a multi-level cross-linked structure, stable dispersion of ZnO NPs and ZnO are achieved. 2+ The sustained release of the hydrogel imparts excellent mechanical properties, exudate management capabilities, and photothermal synergistic antibacterial effects, ultimately providing a multifunctional hydrogel dressing that adapts to the wound microenvironment and offers synergistic functionality.

[0006] The specific plan is as follows: The first aspect of this solution provides a method for preparing a photoresponsive multifunctional nanocomposite hydrogel, comprising the following steps: S1, Preparation of Mixture A: Add acrylamide to deionized water and stir at room temperature until completely dissolved. Add gelatin, heat to 50°C and continue stirring. After cooling to room temperature, add N,N'-methylenebisacrylamide and stir until homogeneous. S2, Preparation of mixture B: Add carboxymethyl chitosan to deionized water, stir at room temperature, and let it dissolve completely overnight. Add zinc oxide nanoparticle dispersion and stir evenly. S3, Preparation of hydrogel: Mix equal volumes of mixture A and mixture B, add ammonium persulfate and stir evenly, pour the mixture into a mold, and crosslink and polymerize at 60℃ to obtain PGC-ZnO nanocomposite hydrogel.

[0007] Preferably, the amount of acrylamide added in the mixture A is 1.8g, the amount of deionized water is 8mL, the amount of gelatin added is 0.15g, and the amount of N,N'-methylenebisacrylamide added is 1.8mg.

[0008] Preferably, the amount of carboxymethyl chitosan added in the mixture B is 1g, the amount of deionized water is 8mL, and the zinc oxide nanoparticles in the zinc oxide nanoparticle dispersion are <100nm and account for 0.2% of the total mass of the PGC-ZnO nanocomposite hydrogel.

[0009] Preferably, the molecular weight of the carboxymethyl chitosan is 2 × 10⁻⁶. 6 Degree of carboxylation ≥ 80%.

[0010] Preferably, the amount of ammonium persulfate added in step S3 is 18 mg, and the crosslinking polymerization time is 2-4 h.

[0011] Preferably, the mold used in step S3 is a cylindrical mold or a dumbbell-shaped polytetrafluoroethylene mold.

[0012] The second aspect of this solution provides a photoresponsive multifunctional nanocomposite hydrogel, which is prepared according to the preparation method of the photoresponsive multifunctional nanocomposite hydrogel described in the first aspect.

[0013] The third aspect of this solution provides an application of the photoresponsive multifunctional nanocomposite hydrogel as described in the second aspect in the preparation of wound dressings.

[0014] Preferably, the wound dressing is combined with photothermal therapy to promote wound healing.

[0015] The beneficial effects of this invention are as follows: Innovative Structure Achieves Functional Synergy: Through the innovative combination of "ZnO NPs-hydrogel," the aggregation problem of ZnO NPs is solved by leveraging coordination and physical entanglement, while the hydrogel network is used to realize Zn 2+ Sustained release ensures long-lasting antibacterial activity while avoiding biotoxicity, adapting to the dynamic needs of the wound microenvironment. Excellent mechanical properties: Through the synergistic effect of multi-level cross-linked structure (covalent backbone - coordination network - physical entanglement), it can stably cover the wound and resist external mechanical stimulation, avoiding secondary damage; Strong wound management capabilities: The hydrogel can efficiently absorb wound exudate and has good swelling adaptability in different pH environments (pH 6.4-8.4), which can cope with wounds in different pathological states, maintain a moist wound environment, and prevent exudate accumulation, which is in line with the theory of moist healing. The hydrogel of this invention meets the ISO 10993-5 biocompatibility standard, has no obvious cytotoxicity or hematologic toxicity, and provides a good microenvironment for cell adhesion and proliferation; Outstanding antibacterial efficiency: Under near-infrared light irradiation, the photothermal effect of the hydrogel and the antibacterial effect mediated by ZnO NPs form a synergistic effect, which can quickly eliminate Gram-negative bacteria (such as Escherichia coli) and Gram-positive bacteria (such as Staphylococcus aureus), and is not prone to drug resistance, making it especially suitable for infected wounds; Significant healing-promoting effect: Zn 2+ The sustained-release CMCS relieves oxidative stress in the wound, and the two work synergistically to regulate the wound microenvironment, accelerate angiogenesis and epithelialization, and improve the quality of wound healing. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the preparation process and wound repair mechanism of the PGC-ZnO nanocomposite hydrogel of the present invention.

[0017] Figure 2 Figures (a), (b), (c), and (d) are scanning electron microscope images and aperture sizes of Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1, respectively.

[0018] Figure 3 Figures (a) and (b) show the compressive stress-strain curves of Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 1, and the cyclic stress-strain curve of Example 1, respectively.

[0019] Figure 4 The graphs show the equilibrium swelling rates of Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1 under different pH conditions.

[0020] Figure 5Figures (a) and (b) show the cell viability and hemolysis rate of Comparative Examples 1, 2, 3 and 1, respectively.

[0021] Figure 6 Figures (a), (b), and (c) show the photothermal heating effect and antibacterial rate curves of Comparative Example 1, Comparative Example 2, Comparative Example 3, and Example 1, respectively.

[0022] Figure 7 Figures (a), (b), and (c) show photographs of wound healing, healing rate statistics, and corresponding wound area statistics in a rat full-thickness skin defect model of Example 1 and Comparative Example 1, respectively. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Example 1: Please refer to Figure 1 This embodiment discloses a method for preparing a photoresponsive multifunctional nanocomposite hydrogel, comprising the following steps: S1. Add 1.8g AM (Acrylamide) to a beaker containing 8mL of deionized water and stir continuously at room temperature for 30 minutes.

[0025] S2, add 0.15g Gel (Gelatin), heat to 50℃ and continue stirring for 30 minutes.

[0026] S3, after cooling to room temperature, add MBA (N,N'-methylenebisacrylamide) and stir for 5 minutes until evenly dispersed.

[0027] S4, take another 1g CMCS (Carboxymethyl chitosan), add 8mL of deionized water, and stir overnight at room temperature until completely dissolved.

[0028] S5, add ZnO NPs dispersion to CMCS solution, and make the mass fraction of ZnO NPs in the final hydrogel 0.2%.

[0029] S6. Mix the two solutions obtained in steps S3 and S5 in equal volumes, add 18 mg of APS (ammonium persulfate) and stir until homogeneous.

[0030] S7. The mixed solution is poured into a mold and crosslinked and polymerized at 60°C to obtain the PGC-ZnO nanocomposite hydrogel sample of Example 1. The mold used is either a cylindrical mold or a dumbbell-shaped polytetrafluoroethylene mold.

[0031] The PGC-ZnO nanocomposite hydrogel has a multi-level cross-linked structure, including a covalent backbone formed by polyacrylamide (PAAm) and ZnO. 2+ The coordination network formed with CMCS carboxyl groups and Gel amino / carboxyl groups, and the physical entanglement (IPN) between PAAm and Gel.

[0032] like Figure 2 The electron microscopy surface morphology of the sample in Example 1 is shown in (d). It can be observed that due to the multi-level cross-linking mechanism, the average pore size of Example 1 is the smallest (average pore size is 13.13 μm). Small diameter pores (<50 μm) are beneficial to cell adhesion, proliferation and drug delivery. In addition, the adhesion of ZnO NPs can be observed on the surface of the hydrogel pores.

[0033] Comparative Example 1: The preparation method of the photoresponsive multifunctional nanocomposite hydrogel of Comparative Example 1 includes the following steps: S1. Add 1.8g AM to a beaker containing 8mL of deionized water and stir continuously at room temperature for 30 minutes.

[0034] S2, after cooling to room temperature, add MBA and stir for 5 minutes until evenly dispersed.

[0035] Add S3 and APS, and stir at room temperature for 5 minutes until completely dissolved.

[0036] S4. Pour the mixed solution into a mold and crosslink it at 60°C to obtain the pure PAAM hydrogel of Comparative Example 1.

[0037] like Figure 2 The electron microscope image (a) shows the surface morphology of the sample in Comparative Example 1. It can be observed that the pure PAAm hydrogel has a loose and porous structure with a large pore size and an average pore size of 20.98 μm.

[0038] Comparative Example 2: The preparation method of the photoresponsive multifunctional nanocomposite hydrogel of Comparative Example 2 includes the following steps: S1. Add 1.8g AM to a beaker containing 8mL of deionized water and stir continuously at room temperature for 30 minutes.

[0039] S2, add 0.15g Gel, heat to 50℃ and continue stirring for 30 minutes.

[0040] S3, after cooling to room temperature, add MBA and stir for 5 minutes until evenly dispersed.

[0041] Add S4 and APS, and stir at room temperature for 5 minutes until completely dissolved.

[0042] S5. Pour the mixed solution into a mold and crosslink it at 60°C to obtain the PAAm / Gel hydrogel of Comparative Example 2.

[0043] like Figure 2 Figure (b) shows the surface morphology of the sample in Example 2 under an electron microscope. It can be observed that the PAAm / Gel hydrogel exhibits a dense honeycomb porous structure with an average pore size reduced to 15.02 μm. This change is due to the interpenetrating network structure formed between the Gel and PAAm molecular chains.

[0044] Comparative Example 3: The preparation method of the photoresponsive multifunctional nanocomposite hydrogel of Comparative Example 3 includes the following steps: S1. Add 1.8g AM to a beaker containing 8mL of deionized water and stir continuously at room temperature for 30 minutes.

[0045] S2, add 0.15g Gel, heat to 50℃ and continue stirring for 30 minutes.

[0046] S3, after cooling to room temperature, add MBA and stir for 5 minutes until evenly dispersed.

[0047] S4, take another 1g of CMCS, add 8mL of deionized water, and stir overnight at room temperature until completely dissolved.

[0048] S5. Mix the two solutions of the above two volumes in equal volumes, add 18 mg of APS and stir until homogeneous.

[0049] S6. Pour the mixed solution into a mold and crosslink it at 60°C to obtain the PAAm / Gel / CMCS hydrogel of Comparative Example 3.

[0050] like Figure 2 The electron microscope image (c) shows the surface morphology of the sample in Comparative Example 3. It can be observed that after the addition of CMCS, its filling effect further reduces the pore size of the PAAm / Gel / CMCS hydrogel, with the average pore size decreasing to 14.42 μm.

[0051] Mechanical tests were conducted at room temperature using an electronic universal testing machine equipped with a 500N tensile sensor. Compression tests were performed using cylindrical hydrogel samples with a diameter of 15mm and a height of 15mm, at a compression rate of 2mm / min. Figure 3 The horizontal axis represents Compression strain, and the vertical axis represents Compression stress. Figure 3(a) It can be seen that the PGC-ZnO nanocomposite hydrogel in Example 1 exhibits the highest compressive stress. This proves that, according to... Figure 3 (b) The PGC-ZnO nanocomposite hydrogel in Example 1 does not suffer structural damage even after multiple compressions under high strain, and can resist external damage when applied to human wound dressings.

[0052] like Figure 4 The figure shown is an analysis chart of the equilibrium swelling rate of samples from Example 1 and Comparative Examples 1-3 after swelling tests. Figure 4 The vertical axis represents ESR (equilibrium swelling ratio). From... Figure 4 As can be seen, under different pH conditions, the equilibrium swelling ratio of Example 1 is lower than that of other comparative samples. It is not too large, which would cause cracking during use, nor too small, which would result in insufficient capacity to absorb wound exudate. It can achieve a balance between absorbing exudate and maintaining structural stability.

[0053] Figure 5 In (a), the vertical axis represents Cell viability of control, and the horizontal axis represents Culture time. Figure 5 (a) It can be seen that the number of viable cells increased significantly from day 1 to day 5 throughout the entire cell compatibility test. In Example 1, the cell viability rate reached as high as 130% on day 5, although due to Zn 2+ The concentrated release was slightly lower than that of the control sample, but it still showed a positive effect. Furthermore, Figure 5 The vertical axis in (b) represents the hemolysis ratio. Figure 5 (b) The blood compatibility test showed that none of the four groups of samples in Example 1 and Comparative Examples 1-3 showed obvious hemolysis, indicating that they have the potential for clinical application.

[0054] The PGC-ZnO nanocomposite hydrogel in Example 1 is suitable for preparing wound dressings. These dressings are suitable for skin wounds caused by mechanical injury, burns, and scalds, and are especially suitable for infected wounds. When using the wound dressing, it is preferable to use it in conjunction with 808nm near-infrared laser irradiation, as the synergistic effect of photothermal ablation and ZnO NPs-mediated bactericidal action enhances the antibacterial effect.

[0055] Figure 6 (a) is a temperature rise image of four groups of samples, including Example 1 and Comparative Examples 1-3, under 808nm laser irradiation. As can be seen from the image, the sample of Example 1 has obvious temperature rise changes and has great potential for subsequent antibacterial and in vivo treatment. Figure 6 (b) and Figure 6(c) The left ordinate represents Antibiofilm efficiency, and the right ordinate represents OD (optical density), where NIR(-) indicates no near-infrared laser irradiation and NIR(+) indicates near-infrared laser irradiation. Figure 6 (b) and Figure 6 (c) The antibacterial rate showed that Comparative Examples 1 and 2 had extremely low antibacterial rates. Example 1, when combined with PTT, exhibited the highest antibacterial efficiency, which is attributed to the excellent photothermal effect and active bactericidal properties of ZnO NPs. It was demonstrated that the PGC-ZnO hydrogel significantly inhibited the growth of Escherichia coli and Staphylococcus aureus, exhibiting strong antibacterial activity against both Gram-negative and Gram-positive bacteria. Furthermore, the antibacterial activity and photothermal properties were primarily related to the doped ZnO NPs.

[0056] The wound healing effects of Example 1 and Comparative Example 1 were verified in a rat wound model. The results are as follows: Figure 7 As shown in (a), the combination of Example 1 and PTT showed the best wound healing effect, with synergistic effect producing excellent antibacterial effect and controlling the inflammatory response in the early stage of wound healing. Figure 7 (b) The vertical axis represents Wound contraction. Figure 7 (b) shows that after 14 days, the wound healing rate of Example 1+PTT combination reached 99%, far exceeding the performance of other comparative examples. When ZnO NPs are combined with PTT treatment, they can also promote fibroblast adhesion and proliferation and accelerate epithelial regeneration. Figure 7 (c) The vertical axis represents the wound area. Figure 7 (c) The line graph of wound area corresponds to the actual image. The trend of the line graph of wound area shows that the slope of the curve of Example 1 combined with PTT is significantly greater than that of other groups, which proves its positive role in the inflammatory phase.

[0057] The PGC-ZnO hydrogel dressing prepared by this invention can be cut to a suitable size according to the wound size and directly applied to wounds such as mechanical injuries, burns, and scalds, and fixed with the assistance of medical tape. For infected wounds, it can be used in conjunction with an 808 nm near-infrared laser (2W·cm). -2 Irradiation for 10 minutes enhances the antibacterial effect. This dressing is suitable for wound care in medical institutions at all levels, and has significant advantages, especially for wounds with a large amount of exudate and a high risk of infection, showing broad prospects for clinical translation.

[0058] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any simple modifications, alterations, and equivalent changes made to the embodiments based on the technical essence of the invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a photoresponsive multifunctional nanocomposite hydrogel, characterized in that, Includes the following steps: S1, Preparation of Mixture A: Add acrylamide to deionized water and stir at room temperature until completely dissolved. Add gelatin, heat to 50°C and continue stirring. After cooling to room temperature, add N,N'-methylenebisacrylamide and stir until homogeneous. S2, Preparation of mixture B: Add carboxymethyl chitosan to deionized water, stir at room temperature, and let it dissolve completely overnight. Add zinc oxide nanoparticle dispersion and stir evenly. S3, Preparation of hydrogel: Mix equal volumes of mixture A and mixture B, add ammonium persulfate and stir evenly, pour the mixture into a mold, and crosslink and polymerize at 60℃ to obtain PGC-ZnO nanocomposite hydrogel.

2. The method for preparing the photoresponsive multifunctional nanocomposite hydrogel according to claim 1, characterized in that, The amount of acrylamide added in the mixture A is 1.8g, the amount of deionized water is 8mL, the amount of gelatin added is 0.15g, and the amount of N,N'-methylenebisacrylamide added is 1.8mg.

3. The method for preparing the photoresponsive multifunctional nanocomposite hydrogel according to claim 1, characterized in that, The amount of carboxymethyl chitosan added in the mixture B is 1g, the amount of deionized water is 8mL, and the zinc oxide nanoparticles in the zinc oxide nanoparticle dispersion are <100nm and account for 0.2% of the total mass of the PGC-ZnO nanocomposite hydrogel.

4. The method for preparing the photoresponsive multifunctional nanocomposite hydrogel according to claim 3, characterized in that, The molecular weight of the carboxymethyl chitosan is 2 × 10⁻⁶. 6 Degree of carboxylation ≥ 80%.

5. The method for preparing the photoresponsive multifunctional nanocomposite hydrogel according to claim 1, characterized in that, In step S3, the amount of ammonium persulfate added is 18 mg, and the cross-linking polymerization time is 2-4 h.

6. The method for preparing the photoresponsive multifunctional nanocomposite hydrogel according to claim 1, characterized in that, The mold used in step S3 is a cylindrical mold or a dumbbell-shaped polytetrafluoroethylene mold.

7. A photoresponsive multifunctional nanocomposite hydrogel, characterized in that, The photoresponsive multifunctional nanocomposite hydrogel was prepared according to any one of claims 1-6.

8. The application of the photoresponsive multifunctional nanocomposite hydrogel according to claim 7 in the preparation of wound dressings.

9. The application according to claim 8, characterized in that, The wound dressing is combined with photothermal therapy to promote wound healing.

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