Photosensitive MOFs nano-enzyme, preparation method thereof and application of photosensitive MOFs nano-enzyme in biological light fermentation

Abstract

The invention discloses a preparation method of photosensitive MOFs nano-enzyme and application of the photosensitive MOFs nano-enzyme in biological light fermentation. According to the method, the photosensitive dye is uniformly distributed on the surface and inside of the MOFs based on the coordination effect of the MOFs and the photosensitive dye. The method is characterized in that the MOFs composite material is stable in physicochemical property and shows photosensitivity and nano-enzyme multifunctionality. The composite material has adjustable photosensitive performance, can show rapid separation of current carriers under the action of an external light source, and shows excellent nano-enzyme activity. The MOFs composite material is proved to have good biocompatibility and can selectively remove reactive oxygen species (ROS). According to the preparation method, the raw materials are wide in source and easy to obtain, the preparation process is simple, the controllability is good, the component particle size is adjustable, and the photo-fermentation photosensitive nano-enzyme prepared through the method is good in crystallization degree, stable in structure, high in specificity and capable of being widely applied to the fields of energy, materials, environmental science and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanoformulations, and specifically relates to a photosensitive MOFs nanozyme, a preparation method thereof, and an application thereof in biological photofermentation. Background Art

[0002] Purple non-sulfur bacteria (such as Rhodobacter sphaeroides, Rhodobacter sphaeroides ) are an important class of photosynthetic microorganisms that can use light energy to convert organic substrates into high-value-added products such as hydrogen under conditions of nitrogen deficiency. However, their photofermentation efficiency is limited by multiple factors, including low light energy utilization, insufficient electron transfer efficiency, and rapid recombination of photogenerated carriers. In addition, intermediate metabolites (such as acetate and butyrate) produced during photofermentation may inhibit bacterial activity, further reducing hydrogen production. Therefore, improving light energy utilization efficiency and electron transfer efficiency has become a key challenge in the field of photofermentation.

[0003] To address these issues, researchers have proposed a variety of improvement strategies, including optimizing bacterial culture conditions, introducing exogenous electron carriers, establishing co-culture systems, and developing novel photocatalytic materials. Among these, the use of nanomaterials to enhance light absorption and electron transfer efficiency is considered a promising solution. For example, by introducing semiconductor materials (such as TiO2, ZnO, and CdS) or metal-organic frameworks (MOFs) as photocatalysts, light energy utilization can be effectively improved and electron transfer can be facilitated. MOFs, due to their high specific surface area, tunable light absorption properties, and excellent photoelectric properties, have broad application prospects in the field of photofermentation. MOFs can be modified with photosensitive groups (such as porphyrins and anthraquinones) to enhance light absorption capacity, and their porous structure facilitates the mass transfer of substrates and products. Furthermore, MOFs can act as electron carriers, accelerating the transfer of photogenerated electrons and thus improving photofermentation efficiency.

[0004] Nanozymes are a class of nanomaterials with enzyme-like catalytic activity that mimic the catalytic function of natural enzymes while offering advantages such as high stability, low cost, and ease of modification. MOF nanozymes are functionalized nanomaterials based on MOFs. By introducing metal nodes (such as Fe, Cu, and Co) or functional ligands (such as porphyrins and imidazoles) with enzyme-like catalytic activity, they are endowed with catalytic abilities that mimic those of natural enzymes (such as peroxidases and oxidases). In photofermentation, MOF nanozymes, through their porous structure and high surface area, effectively adsorb substrates and facilitate the transfer of photogenerated electrons, thereby improving light energy utilization efficiency and hydrogen yield. For example, Fe-MOF nanozymes can mimic the activity of peroxidases, catalyzing the decomposition of ROS during photofermentation and mitigating oxidative stress damage to bacteria. Porphyrin-modified MOF nanozymes, on the other hand, can enhance light absorption and promote the separation and transfer of photogenerated electrons. Furthermore, the high stability and controllability of MOF nanozymes hold great promise for their application in photofermentation, providing new insights into the construction of efficient photofermentation systems. In addition, by combining nanozymes with photosensitive materials, the efficiency of light energy utilization can be further improved and the separation and transfer of photogenerated electrons can be promoted.

[0005] Although existing technologies have made some progress in improving the efficiency of photofermentation, there are still many defects. First, traditional photocatalytic materials are prone to photocorrosion under light conditions, resulting in a decrease in catalytic activity. Second, nanozymes and photosensitive materials have poor biocompatibility and may inhibit bacterial activity. In addition, the catalytic activity and selectivity of existing materials still need to be further improved. Therefore, the development of a new material with high photocatalytic activity, excellent biocompatibility and stability is of great significance to promoting the development of photofermentation technology. Summary of the Invention

[0006] The present invention addresses the current state of the art, which presents problems such as the insufficient stability of natural enzymes in photofermentation, limited catalytic activity, susceptibility to environmental factors, and high production costs; severe photocorrosion, poor biocompatibility, and low catalytic selectivity of traditional photocatalytic materials; the generation of harmful byproducts during photofermentation by single nanozymes or photosensitive materials; unsustainable photofermentation efficiency; low substrate conversion rate; and high photogenerated carrier recombination rate. The present invention aims to provide a photosensitive MOF nanozyme, a preparation method, and its application in biophotofermentation.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a photosensitive MOFs nanozyme, which is composed of a MOFs nanozyme substrate with diversity and enzymatic activity and a photosensitive substance loaded thereon. The MOFs nanozyme substrate includes a core framework self-assembled by metal ions or metal clusters and organic ligands through coordination bonds; the photosensitive substance includes an ultraviolet light, visible light or near-infrared light photosensitizer.

[0008] Furthermore, the photosensitizer is any one of rubephora sodium salt (RB), eosin (eosin Y, EY) and 2-methylimidazole.

[0009] The MOFs nanozyme substrate is any one of single MOFs, modified MOFs, MOFs complexed with natural enzymes, and MOF derivatives.

[0010] The MOFs nanozyme substrate has the function of simulating the activity of any one of peroxidase, oxidase, catalase, superoxide dismutase and hydrolase.

[0011] The loading is carried out by any one of physical adsorption, hydrogen bonding, van der Waals force and electrostatic interaction.

[0012] The method for preparing a photosensitive MOFs nanozyme comprises: Step 1: reacting the metal salt with the organic ligand, washing, and drying to obtain MOFs nanozyme; Step 2: Load the photosensitive substance onto the MOFs nanozyme obtained in step 1, vacuum dry, and obtain the photosensitive MOFs nanozyme.

[0013] In step 1, the molar ratio of the metal salt to the organic ligand is 1-3:1, the reaction temperature is 100-120° C., and the reaction time is 18-24 h.

[0014] Furthermore, the organic ligand is H2BDC.

[0015] Furthermore, the molar ratio of the metal salt to the organic ligand is 2:1.

[0016] In step 2, the molar ratio of the photosensitive substance to the MOFs nanozyme is 1:1. The application of the photosensitive MOFs nanozyme in biophotofermentation.

[0017] A bioluminescent fermentation method comprises placing a photosensitive MOFs nanozyme and a photofermentation microorganism in a fermentation medium, adjusting the pH value, and performing anaerobic fermentation.

[0018] Furthermore, the photofermentative microorganism is any one of purple non-sulfur bacteria or spherical red bacteria having hydrogen production capability.

[0019] The concentration of the photosensitive MOFs nanozyme in the fermentation system is 10-200 mg / L, the optical density of the photofermentation microorganism at 660 nm at the beginning of fermentation is controlled to be 0.2, and the pH value is adjusted to 6-9; the anaerobic fermentation conditions are fermentation under a halogen light intensity of 5000 lux for 50-70 hours.

[0020] The fermentation medium comprises: 15 g / L monosaccharide, 1.0 g / L L-glutamic acid, 0.04 g / L L-aspartic acid, 1 g / L sodium chloride, 25 mL / L KH2PO4-K2HPO4, 9 mL / L trace element solution, 2.5 mL / L vitamin concentrated solution, and water as solvent; wherein the vitamin concentrated solution (250 mL) contains the following substances: 11 mg thiamine hydrochloride, 14 mg nicotinic acid, and 0.8 μg biotin, and the solvent is water; the trace element solution (1 L) comprises: 10 g / L nitrilotriacetic acid, 15 g / L MgSO4·7H2O, 1.0 g / L FeSO4·7H2O, (NH4)6Mo7O 24 ·4H2O 0.008 g / L, CaCl2·2H2O 3 g / L, solvent is water.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a photosensitive MOFs nanozyme for biophotofermentation. The photosensitive MOFs nanozyme combines the high specific surface area, porosity and controllability of MOFs with the light response characteristics of photosensitive substances, enabling the nanozyme to play a catalytic role under light conditions. This combination provides a new catalyst option for applications such as biophotofermentation, has potential high efficiency and selectivity, and is non-toxic to microorganisms.

[0022] Furthermore, by selecting different types of MOFs nanozyme substrates, the performance of the nanozymes, such as catalytic activity, stability, and biocompatibility, can be further regulated. This diversity allows for customized design of nanozymes to meet the needs of different applications. Nanozymes can play a catalytic role similar to that of natural enzymes in biophotofermentation, but at the same time have higher stability and reusability. This helps to improve fermentation efficiency and reduce production costs. Loading photosensitizers through physical adsorption and hydrogen bonding interactions can ensure uniform distribution and stable loading of photosensitizers on the MOFs nanozyme substrate. This loading method is simple and easy, has little effect on the catalytic performance of the nanozyme, and is conducive to maintaining the efficiency and stability of the nanozyme.

[0023] The method for preparing photosensitive MOFs nanozymes of the present invention can obtain MOFs nanozymes with photocatalytic activity through simple chemical reactions and loading steps; the preparation conditions are mild, the crystallization performance is stable, the loading amount of the photosensitizer is high and it is not easy to aggregate, the light absorption performance is adjustable, the applicable solvent range is wide, it has long-term stability, and it is easy to produce on a large scale, which provides the possibility for the industrial application of photosensitive MOFs nanozymes.

[0024] The application provided by the present invention, the application of photosensitive MOFs nanozymes in biological photofermentation, can significantly improve fermentation efficiency and increase the yield of target products. The photocatalytic performance of nanozymes helps promote the growth and metabolism of microorganisms, while removing harmful substances (such as ROS) in the fermentation system and protecting microbial cells from damage by oxidative stress.

[0025] The present invention utilizes the method of biofermentation of photosensitive MOFs nanozymes, combines the advantages of photosensitive MOFs nanozymes and photofermentation microorganisms, and realizes an efficient and stable biological photofermentation process by adjusting pH value, anaerobic fermentation and other conditions. This method promotes the uptake of biologically available substrates, the utilization of light energy in the fermentation system, the stability of the microenvironment of the fermentation system, and the production of products in the photofermentation system, thereby increasing the hydrogen production in the photofermentation system. Compared with the control group, the cumulative hydrogen production can be effectively improved, which is expected to provide a new technical means for the production of renewable energy (such as hydrogen). BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a transmission electron microscopy (TEM) morphology image of the MIL-101 / RB photosensitive nanozyme prepared in Example 1 of the present invention; Figure 2 This is the X-ray diffraction (XRD) spectrum of the MIL-101 / RB photosensitive nanozyme prepared in Example 1 of the present invention; Figure 3 This is the UV-visible diffuse reflectance spectrum (DRS) of the MIL-101 / RB photosensitive nanozyme prepared in Example 1 of the present invention; Figure 4 The effect of the MIL-101 / RB photosensitive nanozyme prepared in Example 1 of the present invention on the ROS intensity of the photofermentation hydrogen production system; Figure 5 This is the effect of the MIL-101 / RB photosensitizing nanozyme prepared in Example 1 of the present invention on the cumulative hydrogen production of the photofermentation hydrogen production system. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the concept of the present invention and the technical effects produced in conjunction with the embodiments, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. The test methods used in the embodiments are all conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can all be reagents and materials obtained from commercial channels.

[0028] The Rhodobacterium sphaeroides used in the present invention is Rhodobacterium sphaeroides ( Rhodobacter sphaeroides ) HTP1, deposited in the General Microbiology Center of China General Microbiological Culture Collection Committee, address: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Postal Code: 100101, with the deposit number CGMCC No. 33696 and the deposit date March 3, 2025. The proposed classification name is: Rhodobacterium sphaeroides ( Rhodobacter sphaeroides ), which can be purchased through other public channels such as the China General Microbiology Center (CGMCC) of the China Microorganism Culture Collection Administration.

[0029] Example 1 This embodiment provides a method for preparing a photosensitive MIL-101 (Fe) / rosin sodium salt (RB) nanozyme material. The specific preparation process is as follows: (1) Preparation of MIL-101(Fe) nanomaterials 1.62 g of FeCl3·6H2O and 0.50 g of terephthalic acid (H2BDC) were dissolved in 50 mL of N,N-dimethylformamide (DMF) to obtain a mixed solution. The mixed solution was transferred to a 100 mL screw-top bottle, which was sealed and placed in an oven. The bottle was heated at 110°C for 20 h. After the reaction, the bottle was removed, cooled to room temperature, and centrifuged. The product was washed three times with DMF and ethanol, respectively, and dried in a vacuum oven at 60°C for 12 h to obtain MIL-101(Fe) nanomaterials.

[0030] (2) Preparation of MIL-101 / RB photosensitive nanozyme Accurately weigh 10 mg of MIL-101(Fe) nanomaterials, add it to 1 mL of deionized water, and ultrasonically disperse it for 5-10 minutes to form a uniform suspension to obtain a MIL-101 aqueous solution; use a pipette to accurately draw 1 mL of 6 mg / mL- bengal sodium salt (RB) aqueous solution, and add it and 1 mL of RB aqueous solution into a 2 mL centrifuge tube, place the centrifuge tube on a magnetic stirrer, set the stirring speed to 200 rpm, and stir and mix for 10 minutes. During the stirring process, bengal sodium salt (RB) molecules will gradually enter the pores of MIL-101 or adsorb on its surface to obtain a MIL-101 / bengal sodium salt (RB) complex; after stirring, remove the centrifuge tube from the magnetic stirrer, place it in a centrifuge, centrifuge at 8,500 rpm for 3 minutes, discard the supernatant, and add 1 mL of deionized water, gently blow with a pipette to resuspend the deposited MIL-101 / red tiger sodium salt (RB) complex, put it into the centrifuge again, centrifuge at 8,500 rpm for 3 min, repeat this washing operation three times to fully remove the unadsorbed RB molecules; after washing, discard the supernatant, place the centrifuge tube containing the MIL-101 / red tiger sodium salt (RB) complex in a vacuum oven at 60°C and dry it for 12 h to remove residual moisture, thereby obtaining the dried MIL-101 / red tiger sodium salt (RB) photosensitive nanozyme.

[0031] Example 2 This example provides a preparation method of a photosensitive MIL-101(Fe) / rosin sodium salt (RB) nanozyme material based on Example 1. The difference lies in the different binding modes of MIL-101(Fe) and rosin sodium salt (RB). The specific steps are as follows: (1) Preparation of MIL-101(Fe) nanomaterials 1.62 g of FeCl3·6H2O and 0.50 g of terephthalic acid (H2BDC) were dissolved in 50 mL of N,N-dimethylformamide (DMF) to obtain a mixed solution. The mixed solution was transferred to a 100 mL screw-top bottle, which was sealed and placed in an oven and heated at 110°C for 20 h. After the reaction, the bottle was removed, cooled to room temperature, and centrifuged. The product was washed three times with DMF and ethanol, respectively, and dried in a vacuum oven at 60°C for 12 h to obtain MIL-101(Fe) nanomaterials.

[0032] (2) Preparation of MIL-101 / RB photosensitive nanozyme Weigh 10 mg of MIL-101(Fe) and 6 mg of bengal sodium salt (RB), add the above raw materials to 2 mL of DMF, transfer to a wire-top bottle with a pipette (ensure sealing), and ultrasonicate (power 200 W, time 10 min) until a uniform suspension is formed; place the sealed wire-top bottle in an oven and react at 100°C for 24 h. After the reaction is completed, take out the wire-top bottle, cool to room temperature, transfer the solution to a centrifuge tube, centrifuge at 8000 rpm for 3 min, and discard the supernatant; add 1 mL of DMF, ultrasonically disperse and centrifuge, repeat washing 3 times, add 1 mL of ethanol, ultrasonically disperse and centrifuge, repeat washing 3 times, transfer the washed solid to a 60°C vacuum oven, and dry it for 12 h to obtain dried MIL-101 / bengal sodium salt (RB) photosensitive nanozyme.

[0033] Example 3 This example provides a method for preparing a photosensitive MIL-101 (Fe) / eosin (eosin Y, EY) nanozyme material based on Example 1. The specific steps are as follows: (1) Preparation of MIL-101(Fe) nanomaterials 1.62 g of FeCl3·6H2O and 0.50 g of terephthalic acid (H2BDC) were dissolved in 50 mL of N,N-dimethylformamide (DMF) to obtain a mixed solution. The mixed solution was transferred to a 100 mL screw-top bottle, which was sealed and placed in an oven. The bottle was heated at 110°C for 20 h. After the reaction, the bottle was removed, cooled to room temperature, and centrifuged. The product was washed three times with DMF and ethanol, respectively, and dried in a vacuum oven at 60°C for 12 h to obtain MIL-101(Fe) nanomaterials.

[0034] (2) Preparation of MIL-101 / eosin (eosin Y, EY) photosensitive nanozyme Weigh 10 mg of MIL-101 powder, add 1 mL of ultrapure water, and ultrasonically disperse for 5 min to form a uniform suspension, MIL-101 suspension; pipette 1 mL of 1 mg / mL eosin (eosin Y, EY) aqueous solution (total EY is 1 mg), transfer the MIL-101 suspension and EY solution to the same beaker or centrifuge tube, with a total volume of 2 mL, place it on a magnetic stirrer, set the speed to 200 rpm, and stir at room temperature for 10 min to mix evenly; obtain a mixed solution; transfer the mixed solution to a centrifuge tube, centrifuge at 8,500 rpm for 3 min, remove the supernatant, add 1 mL of ultrapure water, ultrasonically disperse for 5 s, and centrifuge again (8,500 rpm, 3 min). Repeat washing 3 times to remove eosin (eosin Y, EY) physically adsorbed on the surface. Transfer the precipitate after centrifugation to a culture dish or weighing bottle and dry it in a vacuum oven at 60°C for 12 h, Obtained dried MIL-101-eosin (Eosin Y, EY) composite material.

[0035] Example 4 This example provides a method for preparing a photosensitive MIL-101 (Fe) / rosin sodium salt (RB) nanozyme material based on Example 1. The specific steps are as follows: (1) Preparation of ZIF-8 / Fe3O4 nanomaterials 0.1 g of commercial Fe3O4 nanoparticles (purchased from Aladdin, 20 nm, 99.0%) were weighed and 10 mL of 1% (w / v) silane coupling agent (APTES) ethanol solution (i.e., 100 mg APTES dissolved in 10 mL ethanol) was added. The mixture was ultrasonically treated for 10 min to ensure uniform dispersion of Fe3O4. The dispersion was transferred to a constant temperature oscillator and oscillated at 300 rpm at room temperature (25°C) for 12 h to allow APTES to bind to the Fe3O4 surface through hydrolysis and condensation reaction to form an amino-functionalized layer. The product was centrifuged at 8,500 rpm for 3 min, the supernatant was discarded, and the product was washed repeatedly with ethanol solution three times to remove unreacted APTES. The precipitate was placed in a vacuum oven at 60°C and dried for 12 h to obtain Fe3O4@NH2 nanoparticles.

[0036] (2) Preparation of Fe3O4@NH2-ZIF-8 photosensitive nanozyme 0.05 g of Fe3O4@NH2 nanoparticles were weighed and dispersed in 25 mL of deionized water. The mixture was ultrasonically treated for 5 min, and 0.73 g of 2-methylimidazole (2-MIM, dissolved in 5 mL of water), 1.2 g of Zn(NO3)2·6H2O (dissolved in 5 mL of water), and 0.56 g of NaOH (pH adjusted, dissolved in 5 mL of water) were added in sequence. The mixture was rapidly stirred until the solution was clear and transparent to obtain a mixed solution. The mixed solution was transferred to a constant temperature oscillator and shaken at 300 rpm at room temperature for 5 min. The mixture was allowed to stand for 24 h to obtain a reaction solution. The reaction solution was centrifuged at 8,500 rpm for 3 min, the supernatant was discarded, and the mixture was washed repeatedly with deionized water three times. The precipitate was placed in a vacuum oven at 60°C and dried for 12 h to obtain Fe3O4@NH2-ZIF-8 photosensitive nanozyme.

[0037] Example 5 In this example, based on Examples 1 to 4, the photosensitive nanozyme solution with a concentration of 50 mg / L obtained in Examples 1 to 4 was ultrasonically dispersed for 30 min to ensure uniformity; Inoculate a single colony of Rhodobacter sphaeroides into a Med A liquid medium and irradiate it under a 5000 lux halogen light for 24-48 hours to obtain a light red to red pre-cultured bacterial solution. Use a culture medium without bacteria as a blank control and adjust the optical density of the bacterial solution at 660 nm to 1.0. 660 =1.0 of the Rhodobacter sphaeroides preculture solution (inoculation size of 20%), 50 mg / L of photosensitive MOFs photosensitive nanozyme and fermentation medium were evenly mixed, and the pH value was adjusted to 7.0±0.1. The mixed system was sealed and placed in a magnetic stirring device with a constant temperature of 30°C and 250 rpm. Fermentation was carried out under anaerobic conditions with a halogen light intensity of 5000 lux for 60 h. At the same time, a control ratio (without adding photosensitized nanozyme) was set for performance testing.

[0038] The fermentation medium comprises: 15 g / L monosaccharide, 1.0 g / L L-glutamic acid, 0.04 g / L L-aspartic acid, 1 g / L sodium chloride, 25 mL / L KH2PO4-K2HPO4, 9 mL / L trace element solution, 2.5 mL / L vitamin concentrated solution, and water as solvent; wherein the vitamin concentrated solution (250 mL) contains the following substances: 11 mg thiamine hydrochloride, 14 mg nicotinic acid, and 0.8 μg biotin, and the solvent is water; the trace element solution (1 L) comprises: 10 g / L nitrilotriacetic acid, 15 g / L MgSO4·7H2O, 1.0 g / L FeSO4·7H2O, (NH4)6Mo7O 24 ·4H2O 0.008 g / L, CaCl2·2H2O 3 g / L, solvent is water.

[0039] The Med A medium includes: 2.0 g sodium succinate, 0.5 g ammonium sulfate, 0.1 g L-glutamic acid, 0.04 g L-aspartic acid, 1 g sodium chloride, 960 mL water, pH 7.2, sterilized by moist heat at 121°C for 30 min, filtered, and added with 10 mL / L KH2PO4-K2HPO4, 10-30 mL / L trace element solution, and 0.5-3 mL / L vitamin concentrate solution. The vitamin concentrate solution (250 mL) contains the following substances: 10.0 mg thiamine hydrochloride, 10 mg nicotinic acid, and 0.8 μg biotin, and the solvent is water; the trace element solution (1 L) contains: 15 g / L nitrilotriacetic acid, 15 g / L MgSO4·7H2O, 0.09 g / L FeSO4·7H2O, and (NH4)6Mo7O 24 ·4H2O 0.001~0.015g / L, CaCl2·2H2O 2 g / L, the solvent is water.

[0040] Comparative Example 1 Based on the description of Example 5, except that no photosensitive nanozyme was added.

[0041] 2. Performance Testing Relevant performance tests were performed on Examples 1 to 4 and Comparative Example 1.

[0042] The photosensitive MOFs nanozyme obtained in Example 1 was analyzed and tested, and the TEM image of the material is shown in FIG. Figure 1 As shown in the XRD spectrum Figure 2 As shown, the DRS spectrum is Figure 3 shown.

[0043] See attached Figure 1 The MIL-101 / RB photosensitive nanozyme exhibits a typical MIL-101 particle octahedron structure with microfilamentous protrusions on the surface, indicating that RB is fully bound within the MIL-101 cage.

[0044] See attached Figure 2 , the XRD peaks of MIL-101 / RB and MIL-101 are the same, indicating that the structure of MIL-101 is not destroyed during the adsorption process.

[0045] See attached Figure 3 , DRS showed that the absorption edge of MIL-101-nRB was red-shifted, corresponding to stronger light absorption ability and lower band gap, indicating that "photosensitive" materials with variable band gap can be controllably synthesized by RB adsorption.

[0046] The ROS concentrations of the fermentation broth at the peak of the hydrogen production rate of Example 1 and Comparative Example 1 were compared. Figure 4 shown.

[0047] See attached Figure 4 MIL-101 / RB can resist ROS oxidation, and its concentration is significantly reduced compared with the group of comparative example 1 using only photosynthetic bacteria (Rhodobacterium sphaeroides, HTP), indicating that photosensitive MOFs nanozymes can eliminate oxidative stress and facilitate efficient hydrogen production.

[0048] The cumulative hydrogen production effects at the end of the photofermentation of Example 1 and Comparative Example 1 were compared, and the results are as follows: Figure 5 shown.

[0049] Depend on Figure 5 It can be seen that the addition of photosensitive MOF nanozymes promotes hydrogen production during photofermentation. The combination of MIL-101 and RB (MIL-101 / RB) produced the highest cumulative hydrogen production, indicating a synergistic effect between MIL-101 and RB, which jointly promotes the hydrogen production process. When photosynthetic bacteria (Rhodobacter sphaeroides, Comparative Example 1), MIL-101, or RB were used alone, the hydrogen production was relatively low, indicating that these conditions have limited effects when acting alone. Photosensitive MOF nanozymes can effectively remove ROS from the fermentation system, which is mainly due to the fact that photosensitive MOF nanozymes promote the uptake of bioavailable substrates, the utilization of light energy in the fermentation system, the stabilization of the fermentation system's microenvironment, and the production of products in the photofermentation system, thereby increasing the hydrogen production in the photofermentation system. This invention provides theoretical and technical guidance for the application of photofermentation based on photosensitive nanozymes.

[0050] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A photosensitive MOFs nanozyme, characterized in that: The photosensitive MOFs nanozyme is composed of a MOFs nanozyme substrate with diversity and enzymatic activity and a photosensitive substance loaded thereon. The MOFs nanozyme substrate includes a core framework self-assembled by metal ions or metal clusters and organic ligands through coordination bonds; the photosensitive substance includes an ultraviolet light, visible light or near-infrared light photosensitizer.

2. A photosensitive MOFs nanozyme according to claim 1, characterized in that: The MOFs nanozyme substrate is any one of single MOFs, modified MOFs, MOFs complexed with natural enzymes, and MOF derivatives.

3. A photosensitive MOFs nanozyme according to claim 1, characterized in that: The MOFs nanozyme substrate has the function of simulating the activity of any one of peroxidase, oxidase, catalase, superoxide dismutase and hydrolase.

4. A photosensitive MOFs nanozyme according to claim 1, characterized in that: The loading is carried out by any one of physical adsorption, hydrogen bonding, van der Waals force and electrostatic interaction.

5. The method for preparing a photosensitive MOFs nanozyme according to any one of claims 1 to 4, characterized in that: include: Step 1: reacting the metal salt with the organic ligand, washing, and drying to obtain MOFs nanozyme; Step 2: Load the photosensitive substance onto the MOFs nanozyme obtained in step 1, vacuum dry, and obtain the photosensitive MOFs nanozyme.

6. The method for preparing a photosensitive MOFs nanozyme according to claim 5, characterized in that: In step 1, the molar ratio of the metal salt to the organic ligand is 1-3:1, the reaction temperature is 100-120° C., and the reaction time is 18-24 h.

7. The method for preparing a photosensitive MOFs nanozyme according to claim 5, characterized in that: In step 1, the molar ratio of the photosensitizer to the MOFs nanozyme is 1:

1.

8. Use of a photosensitive MOFs nanozyme according to any one of claims 1 to 4 in biophotofermentation.

9. A bioluminescent fermentation method, characterized in that: The method comprises placing a photosensitive MOFs nanozyme and a photofermentation microorganism according to any one of claims 1 to 4 in a fermentation medium, adjusting the pH value, and performing anaerobic fermentation.

10. The bioluminescent fermentation method according to claim 9, characterized in that: The concentration of the photosensitive MOFs nanozyme in the fermentation system is 10-200 mg / L, the optical density of the photofermentation microorganism at 660 nm at the beginning of fermentation is controlled to be 0.2, and the pH value is adjusted to 6-9; the anaerobic fermentation conditions are fermentation under a halogen light intensity of 5000 lux for 50-70 hours.

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