Membrane material loaded with manganese dioxide modified D-histidine MOF (Metal Organic Framework), preparation method of membrane material and application of membrane material in photodynamic antibiosis and biological membrane removal

Abstract

The invention relates to the technical field of functional membrane materials, in particular to a membrane material loaded with manganese dioxide modified D-histidine MOF, a preparation method of the membrane material and application of the membrane material to photodynamic antibiosis and biological membrane removal. The membrane material is prepared by performing in-situ growth of DHZn MOF on the surface of a substrate membrane by using D-histidine and zinc ions through a hydrothermal method, and performing in-situ generation of MnO2 on the surface of the substrate membrane. The membrane material can be dissociated responsively under the acidic pH of a bacterial infection microenvironment and the action of enzyme, D-histidine, Zn < 2 + > and Mn < 2 + > with antibacterial activity are released, and the synergistic antibacterial effect is achieved. In addition, the MnO2 / DHZn MOF has visible light absorptivity and can generate active oxygen under the irradiation of visible light, so that photodynamic antibiosis and biological membrane removal are realized. The material disclosed by the invention has dual mechanisms of environmental response antibacterial factor release and photodynamic antibiosis, and has a good application prospect in wound dressing and anti-biofilm materials.

Description

Technical Field

[0001] This invention relates to the field of functional membrane materials technology, and in particular to a membrane material loaded with manganese dioxide-modified D-histidine MOF, its preparation method, and its application in photodynamic antibacterial and biofilm removal. Background Technology

[0002] Bacterial infections have become the second leading cause of death worldwide, and antibiotic resistance and biofilm formation have created significant challenges to clinical treatment. Traditional antibiotics are ineffective against "superbugs" such as methicillin-resistant Staphylococcus aureus (MRSA), and biofilms can reduce antibiotic efficacy by up to 1000 times. Even more problematic is that existing nanozymes continuously generate reactive oxygen species (ROS) during the bactericidal process. While these can kill bacteria, excessive oxidative stress can hinder wound healing, creating a vicious cycle of "easy to kill bacteria, difficult to heal." Therefore, there is an urgent need to develop novel antibacterial agents that can simultaneously kill bacteria, inhibit biofilm formation, and scavenge reactive oxygen species.

[0003] Metal-organic frameworks (MOFs) are a class of porous materials composed of metal ions or clusters linked to organic ligands via coordination bonds, exhibiting highly tunable pore structures and large specific surface areas. Due to the diversity of organic molecules and metal ions and the virtually limitless structural possibilities, MOFs have attracted widespread attention in the field of antibacterial and anti-infective applications. The porous structure of MOFs facilitates drug loading, enabling the clearance of biofilms through photodynamic and photothermal methods. However, most MOFs lack targeting and antibacterial functions, hindering highly efficient antibacterial effects. Furthermore, their reliance on external stimuli such as light and heat makes it difficult to precisely target therapeutic effects within the bacterial infection microenvironment. Additionally, the difficulty in molding and recycling MOF powder structures limits their applications. Summary of the Invention

[0004] To address the shortcomings of existing methods, this invention prepares DHZn MOF on the surface of a substrate membrane via a hydrothermal method using D-histidine and zinc ions. Simultaneously, MnO2 is generated in situ on the DHZn MOF surface, resulting in a membrane material loaded with manganese dioxide-modified D-histidine MOF, thus solving the aforementioned problems. Acidic pH and enzymes can dissociate MnO2 / DHZn MOF to generate D-histidine and Zn... 2+ and Mn 2+ This enables responsiveness to the bacterial infection microenvironment, releasing Zn 2+ and Mn 2+ It can bind to bacterial cell membranes and membrane proteins, disrupting their structure. After entering the cell, it disrupts enzymes in the electron transport system and reacts with DNA, achieving a synergistic antibacterial effect. At the same time, MnO2 extends the absorption spectrum of DHZn MOF into the visible light region, realizing photodynamic antibacterial activity under visible light.

[0005] The preparation method of the membrane material of D-histidine MOF loaded with manganese dioxide includes the following steps: (1) Immerse the substrate membrane in an ammonia solution and reflux at 50°C for 2 hours in a three-necked flask with a condenser. After cooling to room temperature, remove the substrate membrane, rinse with deionized water until the pH of the filtrate is 7 (to ensure that the residual ammonia is completely removed), and dry with nitrogen.

[0006] (2) Immerse the pretreated substrate film in zinc nitrate solution and shake at 180 rpm for 1 hour (25°C) in a constant temperature shaking oven. Remove the substrate film and rinse it three times with deionized water.

[0007] (3) Dissolve D-histidine and hexadecyltrimethylammonium bromide (CTAB) in deionized water to prepare a reaction solution. Stir until completely dissolved and then transfer to a 100 mL high-pressure reactor. Suspend the substrate membrane from step (2) vertically in the reaction solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0008] (4) After natural cooling, the substrate membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the substrate membrane loaded with D-histidine MOF (DHZn MOF).

[0009] (5) Immerse the substrate film from step (4) in Tris buffer solution, add KMnO4 aqueous solution dropwise under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0010] (6) Take out the substrate membrane, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain the membrane material of D-histidine MOF loaded with manganese dioxide.

[0011] Preferably, the substrate film is a PET film.

[0012] Preferably, the ammonia solution is 5% ammonia solution.

[0013] Preferably, the concentration of the zinc nitrate solution is 0.1-0.5 mol / L.

[0014] Preferably, the molar ratio of D-histidine to hexadecyltrimethylammonium bromide is 4:1.

[0015] Preferably, the concentration of D-histidine in the reaction solution is 0.40-1.20 mol / L.

[0016] Preferably, the concentration of the Tris buffer is 0.1 mol / L and the pH is 8.

[0017] Preferably, the concentration of the KMnO4 aqueous solution is 1-5 mg / mL.

[0018] Preferably, the volume ratio of Tris buffer and KMnO4 aqueous solution in step (4) is 5:1.

[0019] Furthermore, a membrane material of D-histidine MOF loaded with manganese dioxide modified by the above method is also provided.

[0020] Furthermore, the membrane material of the above-mentioned manganese dioxide-modified D-histidine MOF has applications in photodynamic antibacterial and biofilm removal.

[0021] The beneficial effects of this invention are as follows: This invention utilizes a hydrothermal method to grow DHZn MOF in situ on the surface of a substrate membrane using D-histidine and zinc ions, and to generate MnO2 in situ on its surface, thus obtaining a membrane material loaded with manganese dioxide-modified D-histidine MOF. This membrane material dissociates MnO2 / DHZn MOF under the acidic pH and enzymatic action of the slightly acidic environment at the bacterial infection site, leading to the release of D-histidine and Zn... 2+ and Mn 2+ The release of Zn enables a responsive release to the bacterial infection microenvironment; 2+ With Mn 2+ Both exhibit antibacterial activity, demonstrating a synergistic antibacterial effect. Furthermore, the MnO2 / DHZn MOF extends visible light absorption, achieving photodynamic antibacterial activity under visible light. This invention's material possesses both environmentally responsive antibacterial factor release and photodynamic antibacterial mechanisms, showing promising application prospects in wound dressings and anti-biofilm materials. Attached Figure Description

[0022] Figure 1 FTIR of DHZn MOF and MnO2@DHZn MOF materials prepared in Example 7; Figure 2 SEM images of DHZn MOF and MnO2@DHZn MOF materials prepared in Example 7, scale bar is 200 nm; Figure 3 SEM image of the MnO2@DHZn MOF prepared in Example 7 after soaking in pH 5.5 buffer for 1 h, scale bar is 200 nm; Figure 4 SEM image of MnO2@DHZn MOF prepared in Example 7 after soaking in elastase solution for 2 h, scale bar is 200 nm; Figure 5 SEM images of the membrane materials prepared in Examples 1-6, with a scale bar of 1 μm; Figure 6 The kinetics of zinc ion release from the membranes prepared in Examples 1-2 at pH 7.4 or 5.5; Figure 7The kinetics of zinc ion release from the membranes prepared in Examples 1-2 in buffer or elastase buffer; Figure 8 The UV-Vis spectra (a) and band gaps calculated by the Tauc plot method for the DHZn MOF and MnO2@DHZn MOF prepared in Example 7 are shown in Figure 7. Figure 9 The DHZn MOF and MnO2@DHZn MOF prepared in Example 7 were captured by DMPO under different visible light irradiation times. O2 – and ESR spectrum of OH; Figure 10 The bactericidal rate of the materials prepared in Examples 1-6 and Example 8 against Escherichia coli; Figure 11 The membrane materials prepared in Examples 1-6 and Example 8 demonstrate the ability to inhibit biofilm formation under both light and non-light conditions. Detailed Implementation

[0023] Example 1: (1) Immerse a 10cm×10cm PET membrane in 100mL of 5% ammonia solution and reflux at 50°C for 2 hours in a three-necked flask with a condenser. After cooling to room temperature, remove the PET membrane, rinse with deionized water until the pH of the filtrate is 7 (to ensure that the residual ammonia is completely removed), and blow dry with nitrogen.

[0024] (2) Immerse the pretreated PET film in 50 mL of 0.1 mol / L zinc nitrate solution and shake at 180 rpm for 1 h (25 °C) in a constant temperature shaking oven. Remove the PET film and rinse it three times with deionized water.

[0025] (3) Dissolve 20 mmol D-histidine and 0.5 mmol CTAB in 50 mL of deionized water, stir until completely dissolved, and then transfer to a 100 mL high-pressure reactor. Suspend the PET membrane from step (2) vertically in the solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0026] (4) After natural cooling, the PET membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the PET membrane loaded with D-histidine MOF (DHZn MOF).

[0027] (5) Immerse the PET membrane from step (4) in 50 mL of 0.1 mol / L Tris buffer (pH=8.0), add 1 mg / mL KMnO4 aqueous solution dropwise (total addition volume 10 mL) under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0028] (6) Take out the PET membrane, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain the membrane material of D-histidine MOF loaded with manganese dioxide (PET membrane of DHZn MOF loaded with MnO2).

[0029] Example 2: (1) Immerse a 10cm×10cm PET membrane in 100mL of 5% ammonia solution and reflux at 50°C for 2 hours in a three-necked flask with a condenser. After cooling to room temperature, remove the PET membrane, rinse with deionized water until the pH of the filtrate is 7 (to ensure that the residual ammonia is completely removed), and blow dry with nitrogen.

[0030] (2) Immerse the pretreated PET film in 50 mL of 0.2 mol / L zinc nitrate solution and shake at 180 rpm for 1 h (25 °C) in a constant temperature shaking oven. Remove the PET film and rinse it three times with deionized water.

[0031] (3) Dissolve 40 mmol D-histidine and 1 mmol CTAB in 50 mL of deionized water, stir until completely dissolved, and then transfer to a 100 mL high-pressure reactor. Suspend the PET membrane from step (2) vertically in the solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0032] (4) After natural cooling, the PET membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the PET membrane loaded with D-histidine MOF (DHZn MOF).

[0033] (5) Immerse the PET membrane from step (4) in 50 mL of 0.1 mol / L Tris buffer (pH=8.0), add 2 mg / mL KMnO4 aqueous solution dropwise (total addition volume 10 mL) under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0034] (6) Take out the PET membrane, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain a PET membrane of DHZn MOF loaded with MnO2.

[0035] Example 3: (1) Immerse a 10cm × 10cm PET membrane in 100mL of 5% ammonia solution and reflux at 50°C for 2 hours in a three-necked flask equipped with a condenser. After cooling to room temperature, remove the PET membrane, rinse with deionized water until the pH of the filtrate is 7 (ensuring complete removal of residual ammonia), and dry with nitrogen. (Same as Example 1) (2) Immerse the pretreated PET film in 50 mL of 0.3 mol / L zinc nitrate solution and shake at 180 rpm for 1 h (25 °C) in a constant temperature shaking oven. Remove the PET film and rinse it three times with deionized water.

[0036] (3) Dissolve 40 mmol D-histidine and 1 mmol CTAB in 50 mL of deionized water, stir until completely dissolved, and then transfer to a 100 mL high-pressure reactor. Suspend the PET membrane from step (2) vertically in the solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0037] (4) After natural cooling, the PET membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the PET membrane loaded with D-histidine MOF (DHZn MOF).

[0038] (5) Immerse the PET membrane from step (4) in 50 mL of 0.1 mol / L Tris buffer (pH=8.0), add 3 mg / mL KMnO4 aqueous solution dropwise (total addition volume 10 mL) under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0039] (6) Take out the PET membrane, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain a PET membrane of DHZn MOF loaded with MnO2.

[0040] Example 4: (1) Immerse a 10cm×10cm PET membrane in 100mL of 5% ammonia solution and reflux at 50°C for 2 hours in a three-necked flask with a condenser. After cooling to room temperature, remove the PET membrane, rinse with deionized water until the pH of the filtrate is 7 (to ensure that the residual ammonia is completely removed), and blow dry with nitrogen.

[0041] (2) Immerse the pretreated PET film in 50 mL of 0.4 mol / L zinc nitrate solution and shake at 180 rpm for 1 h (25 °C) in a constant temperature shaking oven. Remove the PET film and rinse it three times with deionized water.

[0042] (3) Dissolve 50 mmol D-histidine and 1.25 mmol CTAB in 50 mL of deionized water, stir until completely dissolved, and then transfer to a 100 mL high-pressure reactor. Suspend the PET membrane from step (2) vertically in the solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0043] (4) After natural cooling, the PET membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the PET membrane loaded with D-histidine MOF (DHZn MOF).

[0044] (5) Immerse the PET membrane from step (4) in 50 mL of 0.1 mol / L Tris buffer (pH=8.0), add 4 mg / mL KMnO4 aqueous solution dropwise (total addition volume 10 mL) under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0045] (6) Take out the PET membrane, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain a PET membrane of DHZn MOF loaded with MnO2.

[0046] Example 5: (1) Immerse a 10cm×10cm PET membrane in 100mL of 5% ammonia solution and reflux at 50°C for 2 hours in a three-necked flask with a condenser. After cooling to room temperature, remove the PET membrane, rinse with deionized water until the pH of the filtrate is 7 (to ensure that the residual ammonia is completely removed), and blow dry with nitrogen.

[0047] (2) Immerse the pretreated PET film in 50 mL of 0.5 mol / L zinc nitrate solution and shake at 180 rpm for 1 h (25 °C) in a constant temperature shaking oven. Remove the PET film and rinse it three times with deionized water.

[0048] (3) Dissolve 60 mmol D-histidine and 1.5 mmol CTAB in 50 mL of deionized water, stir until completely dissolved, and then transfer to a 100 mL high-pressure reactor. Suspend the PET membrane from step (2) vertically in the solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0049] (4) After natural cooling, the PET membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the PET membrane loaded with D-histidine MOF (DHZn MOF).

[0050] (5) Immerse the PET membrane from step (4) in 50 mL of 0.1 mol / L Tris buffer (pH=8.0), add 4 mg / mL KMnO4 aqueous solution dropwise (total addition volume 10 mL) under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0051] (6) Take out the PET membrane, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain a PET membrane of DHZn MOF loaded with MnO2.

[0052] Example 6: (1) Immerse a 10cm×10cm PET membrane in 100mL of 5% ammonia solution and reflux at 50°C for 2 hours in a three-necked flask with a condenser. After cooling to room temperature, remove the PET membrane, rinse with deionized water until the pH of the filtrate is 7 (to ensure that the residual ammonia is completely removed), and blow dry with nitrogen.

[0053] (2) Immerse the pretreated PET film in 50 mL of 0.5 mol / L zinc nitrate solution and shake at 180 rpm for 1 h (25 °C) in a constant temperature shaking oven. Remove the PET film and rinse it three times with deionized water.

[0054] (3) Dissolve 60 mmol D-histidine and 1.5 mmol CTAB in 50 mL of deionized water, stir until completely dissolved, and then transfer to a 100 mL high-pressure reactor. Suspend the PET membrane from step (2) vertically in the solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0055] (4) After natural cooling, the PET membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the PET membrane loaded with D-histidine MOF (DHZn MOF).

[0056] (5) Immerse the PET membrane from step (4) in 50 mL of 0.1 mol / L Tris buffer (pH=8.0), add 5 mg / mL KMnO4 aqueous solution dropwise (total addition volume 10 mL) under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0057] (6) Take out the PET membrane, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain a PET membrane of DHZn MOF loaded with MnO2.

[0058] Example 7: (1) Prepare 25 mL of 0.1 mol / L zinc nitrate solution, 25 mL of 20 mmol D-histidine and 0.5 mmol CTAB. Slowly pour the zinc nitrate solution into the histidine solution with stirring, transfer to a 100 mL high-pressure reactor, and hydrothermally react at 180 °C for 24 h.

[0059] (2) After natural cooling, the precipitate was collected by centrifugation at 10,000 rpm and dried under vacuum at 40°C to obtain D-histidine MOF (DHZnMOF).

[0060] (3) Prepare 50 mL of 10 mg / mL DHZn MOF solution, add 1 mg / mL KMnO4 aqueous solution dropwise (total addition volume 10 mL) under ice bath (0-4℃) conditions, and stir vigorously at 300 rpm for 1 h.

[0061] (4) Centrifuge to collect the precipitate, rinse it with plenty of water and methanol, and vacuum dry it at 60°C for 12 hours to obtain MnO2-coated DHZn MOF.

[0062] Example 8: (1) Immerse a 10cm×10cm PET membrane in 100mL of 5% ammonia solution and reflux at 50°C for 2 hours in a three-necked flask with a condenser. After cooling to room temperature, remove the PET membrane, rinse with deionized water until the pH of the filtrate is 7 (to ensure that the residual ammonia is completely removed), and blow dry with nitrogen.

[0063] (2) Immerse the pretreated PET film in 50 mL of 0.1 mol / L zinc nitrate solution and shake at 180 rpm for 1 h (25 °C) in a constant temperature shaking oven. Remove the PET film and rinse it three times with deionized water.

[0064] (3) Dissolve 20 mmol D-histidine and 0.5 mmol CTAB in 50 mL of deionized water, stir until completely dissolved, and then transfer to a 100 mL high-pressure reactor. Suspend the PET membrane from step (2) vertically in the solution and perform a hydrothermal reaction at 180 °C for 24 h.

[0065] (4) After natural cooling, the PET membrane was removed and rinsed with methanol and pure water respectively. It was then vacuum dried at 40°C to obtain the PET membrane loaded with D-histidine MOF (DHZn MOF).

[0066] Figure 1 The FTIR spectra of DHZn MOF and MnO2@DHZn MOF materials prepared in Example 7 are shown. DHZn MOF exhibits FTIR spectra at 3400 cm⁻¹. -1 The peak is broad (OH stretching region) at 1582 cm⁻¹. -1 (C=N stretching), 1422 and 995cm -1 (CN stretch), 1309 and 1143cm -1 (Imidazole bending), and 421cm -1 Characteristic peaks at the (Zn-N stretching) position. In addition to the typical DHZn MOF peaks mentioned above, MnO2@DHZn MOF also exhibits a peak at 524 cm⁻¹. -1 The new peak at the location corresponds to the Mn-O vibration, indicating that MnO2@DHZn MOF was successfully prepared.

[0067] Figure 2 SEM images of the DHZn MOF and MnO2@DHZn MOF materials prepared in Example 7, with a scale bar of 200 nm.

[0068] The MnO2@DHZn MOF prepared in Example 7 was soaked in phosphate buffer (10 mM NaH2PO4) at pH 5.5 for 1 h, the precipitate was collected by centrifugation, and the morphology was observed by SEM. Figure 3 As shown, after acid treatment, the MOF dissociates from a spherical structure into an irregular structure, and the three-dimensional structure collapses.

[0069] Elastase is mainly secreted by neutrophils (the host) or Pseudomonas aeruginosa, and its concentration is significantly increased at sites of bacterial infection (such as pus and chronic wounds). It belongs to the Zn group. Metalloproteinase-dependent enzymes. A Tris-HCl solution (pH=7.4, containing 10 mmol / L CaCl2) containing 50 μg / mL *Pseudomonas aeruginosa* elastase was prepared. The MnO2@DHZn MOF prepared in Example 7 was immersed in the elastase solution for 2 h, centrifuged, and the precipitate was collected. The morphology was observed by SEM. Figure 4 As shown, after enzyme treatment, MOFs dissociate from a spherical structure into an irregular structure, while their three-dimensional structure collapses. The Zn in the active center of the elastase... It has higher coordination affinity and can competitively seize the coordination site of D-histidine, directly weakening the interaction between D-His and Zn in MOF. The coordinate key.

[0070] Figure 5 The images show SEM images of the membrane materials prepared in Examples 1-6. The surface of the untreated PET membrane is relatively smooth, while the surface of the membranes prepared in Examples 1-6 has a large number of particles distributed on it, which are MnO2@DHZn MOF.

[0071] Figure 6 The kinetics of zinc ion release from the membranes prepared in Examples 1-2 are shown in phosphate buffer (10 mM NaH2PO4) at pH 7.4 or phosphate buffer (10 mM NaH2PO4) at pH 5.5. The membranes prepared in Examples 1-2 released only 0.3 mg / L of zinc ions in 3 hours at pH 7.4, and a maximum of 1.75 mg / L of zinc ions in 3 hours at pH 5.5, exhibiting the dissociation characteristics of MOFs under acidic pH conditions.

[0072] Figure 7The kinetics of zinc ion release from the membranes prepared in Examples 1-2 in phosphate buffer (10 mM NaH2PO4) and elastase buffer at pH 7.4 were investigated. The membranes prepared in Examples 1-2 were placed in pH 7.4 buffer and pH 7.4 buffer containing 50 μg / mL elastase. In pH 7.4 buffer, only 0.4 mg / L of zinc ions were released after 4 hours, while under the condition of 50 μg / mL elastase, a maximum release of 1.68 mg / L of zinc ions was observed after 4 hours, demonstrating the MOF dissociation characteristics responsive to elastase.

[0073] The optical properties of the DHZn MOF and MnO2@DHZn MOF prepared in Example 7 were characterized by UV-Vis absorption spectroscopy, such as... Figure 8 As shown in Figure a, DHZn MOFs possess an inherent strong absorption band, with a peak at 220 nm and almost no absorption above 350 nm. Therefore, DHZn MOFs can only be excited by ultraviolet light. In contrast, the intrinsic absorption band of MnO2@DHZn MOF nanocomposites exhibits a blue shift, with a wavelength of 205 nm. Simultaneously, the absorption between 300-500 nm is significantly enhanced, and the broadband absorption in the 250–400 nm range indicates that the absorption region of MnO2@DHZn MOFs has extended into the visible region. Subsequently, through (αhv)... 2 =A(hv-Eg) 2 The formula calculates the band gap Eg. (DHZn MOF) Eg The value is 5.25 eV for MnO2@DHZnMOF. Eg Slightly increased by 0.21 eV ( Eg = 5.46 eV). Eg The increase indicates a reduction in photogenerated electron-hole collisions, thus suppressing electron-hole recombination in the DHZn MOF. Furthermore, Figure 8 The illustration in b also shows another band gap. Eg The value is 2.78 eV, which may indicate that MnO2 with its narrow bandgap will produce defective surface structures. The coupling between DHZn MOF and MnO2 will provide more active surface coordination sites for the generation of active radicals, which is believed to be beneficial for enhancing catalytic activity.

[0074] Electron spin resonance (ESR) spectroscopy: The DHZn MOF and MnO2@DHZn MOF prepared in Example 7 were placed under visible light irradiation, and the electron spin resonance (ESR) was measured using the typical trapping agent 5,5-dimethyl-1-pyrrolline-N-oxide (DMPO). O2- and The formation of OH. For example... Figure 9As shown in a-9d, DHZn MOF illumination for 0 min and 30 min did not produce [a specific effect]. O2 The characteristic is a signal ratio of 1:1.5:1.5:1 and a peak area ratio of 1:2:2:1. OH signal. For MnO2@DHZn MOF, O2 Characteristic signals and The OH signals all increased with time (0, 2, 6, and 8 minutes), indicating that a large amount of OH signals were generated in the MnO2@DHZn MOF composite material. O2 and OH.

[0075] Sterilization test: The membranes prepared in Examples 1-6 and Example 8 were added to a suspension containing 20 mL of bacteria (Escherichia coli) (10 7 After irradiation with a 30W visible light lamp at 37°C or non-light treatment for 2 hours, 20 μL of solution was extracted from each well, diluted, and plated onto Luria-Bertani (LB) agar plates. The bacterial colony counts on the plates were then analyzed. Under non-light conditions, the membranes prepared in Examples 1-6 exhibited a sterilization rate of 59-73%, significantly higher than the 35% in Example 8, demonstrating the synergistic effect of MnO2. Under light conditions, the sterilization rate of the membranes prepared in Examples 1-6 increased to 87-94%, which is attributed to the increased sterilization rate due to the free radicals generated by light.

[0076] Biofilm inhibition assay: *E. coli* was inoculated into 50 mL centrifuge tubes (20 mL per well, 10^7 CFU / mL). LB nutrient solution was changed daily for 5 consecutive days at 37°C. After biofilm formation, the membranes prepared in Examples 1-6 and Example 8 were added, and the tubes were irradiated with a 30W LED lamp at 37°C or treated without light for 6 hours. The membranes and supernatant were removed, and the tubes were washed three times with sterile water. Crystal violet staining solution was added to stain the biofilm. Subsequently, 30% acetic acid solution was added to dissolve the biofilm, and the absorbance at 590 nm was measured using a microplate reader. The control group was treated without membrane material.

[0077] The control group produced biofilms with high absorbances of 2.37 and 2.53 under light and dark conditions, respectively, indicating the highest biofilm quantity. The membrane materials prepared in Examples 1-6 significantly removed biofilms under light treatment, with absorbance as low as 0.19. However, the membrane material prepared in Example 8, lacking MnO2, showed absorbances of 1.94 and 2.14 for biofilms under light and non-light treatments, respectively, demonstrating that MnO2 can significantly enhance the photodynamic biofilm removal effect of the material.

[0078] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a membrane material loaded with manganese dioxide-modified D-histidine MOF, characterized in that, Includes the following steps: (1) Immerse the substrate membrane in an ammonia solution, reflux at 50°C for 2 hours in a three-necked flask with a condenser, cool to room temperature, remove the substrate membrane, rinse with deionized water until the filtrate pH=7, and dry with nitrogen. (2) Immerse the substrate film obtained in step (1) in zinc nitrate solution and shake it at 180 rpm for 1 h in a constant temperature shaking box at 25°C. Remove the substrate film and clean it. (3) Dissolve D-histidine and hexadecyltrimethylammonium bromide in deionized water to prepare a reaction solution. Stir until completely dissolved and transfer to a 100mL high-pressure reactor. Hang the substrate film from step (2) vertically in the reaction solution and perform a hydrothermal reaction at 180℃ for 24h. (4) After natural cooling, the substrate membrane is removed and rinsed with methanol and pure water respectively, and dried to obtain the substrate membrane loaded with D-histidine MOF; (5) Immerse the substrate film from step (4) in Tris buffer solution, add KMnO4 aqueous solution dropwise under ice bath conditions, and stir vigorously at 300 rpm for 1 h; (6) Remove the substrate membrane, wash and dry it to obtain the membrane material of D-histidine MOF loaded with manganese dioxide.

2. The method for preparing the membrane material of D-histidine MOF loaded with manganese dioxide as described in claim 1, characterized in that, The substrate film is a PET film.

3. The method for preparing the membrane material of D-histidine MOF loaded with manganese dioxide as described in claim 1, characterized in that, The ammonia solution is 5% ammonia solution.

4. The method for preparing the membrane material of D-histidine MOF loaded with manganese dioxide as described in claim 1, characterized in that, The concentration of the zinc nitrate solution is 0.1-0.5 mol / L.

5. The method for preparing the membrane material of D-histidine MOF loaded with manganese dioxide as described in claim 1, characterized in that, The concentration of D-histidine in the reaction solution was 0.40-1.20 mol / L; the molar ratio of D-histidine to hexadecyltrimethylammonium bromide was 4:

1.

6. The method for preparing the membrane material of D-histidine MOF loaded with manganese dioxide as described in claim 1, characterized in that, The concentration of the Tris buffer is 0.1 mol / L, and the pH is 8.

7. The method for preparing the membrane material of D-histidine MOF loaded with manganese dioxide as described in claim 1, characterized in that, KMn The concentration of the aqueous solution is 1-5 mg / mL.

8. The method for preparing the membrane material of D-histidine MOF loaded with manganese dioxide as described in claim 1, characterized in that, In step (5), Tris buffer and KMn The volume ratio of the aqueous solution is 5:

1.

9. A membrane material of a manganese dioxide-modified D-histidine MOF prepared by the method described in claims 1-8.

10. The application of a membrane material of D-histidine MOF modified with manganese dioxide as described in claim 9 in photodynamic antibacterial and biofilm removal.

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