Microbial photoelectric carrier and preparation method thereof

Abstract

The present application relates to a kind of microbial photoelectric carrier and its preparation method, including photoelectric carrier and functional bacterial biofilm in situ growth on the surface of the photoelectric carrier;The photoelectric carrier is ITO conductive glass coated with polystyrene microspheres on the surface;The polystyrene microspheres are loaded with semiconductor nanoparticles and ITO nanoparticles.The substrate indium tin oxide ITO of the present application has excellent hydrophilicity, and the substrate is designed with microsphere porous structure, can fully accommodate and allow bacterial penetration growth, facilitate the initial adhesion and long-term colonization of bacteria;At the same time, the pore wall is composed of mesoporous framework, and shows good permeability to nutrients and metabolites.Such water-permeable scaffold structure can effectively isolate bacterial colonies, avoid local excessive accumulation, so that a large number of bacteria can actively carry out metabolic activities in it under the premise of ensuring sufficient material exchange.The present application further strengthens its light response and conductive properties by various nanoparticles.

Description

Technical Field

[0001] This invention belongs to the field of microbial photoelectrochemical systems, specifically relating to a microbial photoelectrocarrier and its preparation method. Background Technology

[0002] Microorganisms have attracted widespread attention in fields such as energy, environmental remediation, and chemical biosynthesis due to their rich metabolic diversity and powerful biotransformation potential. However, the natural metabolic rates of most functional microorganisms are relatively slow, severely limiting their practical application efficiency. To overcome this limitation, researchers have proposed injecting exogenous electrons into microbial systems using electrochemical or photochemical excitation to enhance their intracellular metabolic activity. Electrochemical excitation strategies can be deeply integrated with the increasingly widespread renewable green electricity (such as wind power, hydropower, and photovoltaic power)—these green electricity sources are clean, low-carbon, and sustainable, providing a stable and controllable electron supply for microbial electrochemical reactions. Photochemical excitation can directly utilize sunlight, achieving efficient solar energy conversion through the excellent light-harvesting capabilities of photochemical materials. By converting intermittent renewable energy into an electron flow that microorganisms can directly utilize, it is hoped that the kinetic bottleneck of microbial metabolism can be overcome. However, the effective implementation of this strategy depends on establishing a tight and efficient physical coupling interface between the microorganism and the carrier. Therefore, developing efficient and stable microbial-carrier interfaces has become a research hotspot in this field.

[0003] Currently, commonly used carbon-based carrier materials such as graphite and carbon cloth are widely used in the construction of microbial carriers due to their good electrochemical stability, biocompatibility, and processability. However, their structures often struggle to simultaneously support high-density bacteria while ensuring rapid nutrient transport and timely diffusion of metabolic waste. Secondly, the surfaces of carbon-based materials are generally hydrophobic, resulting in weak electrical interactions with the surfaces of hydrophilic bacterial cells, which hinders efficient electron transfer. Therefore, bacteria immobilized on these carriers tend to form dense biofilms, leading to slow electron transport and reduced mass transfer efficiency, thereby inhibiting bacterial proliferation and metabolic activity.

[0004] Therefore, how to select a suitable photoelectric carrier to construct an efficient microbial photoelectric carrier is a research hotspot in this technical field. Summary of the Invention

[0005] This invention provides a microbial photoelectric carrier and its preparation method. The substrate of this invention, indium tin oxide (ITO), possesses excellent hydrophilicity, and is designed with a microsphere porous structure, forming interconnected macropores that can fully accommodate and allow bacteria to penetrate and grow, facilitating initial adhesion and long-term colonization. Simultaneously, the pore walls are composed of a mesoporous framework, exhibiting good permeability to nutrients and metabolic products. This permeable scaffold structure effectively isolates bacterial colonies, preventing excessive local accumulation, thus allowing a large number of bacteria to actively carry out metabolic activities while ensuring sufficient material exchange. This invention further enhances its photosensitivity and conductivity through various nanoparticles. This invention aims to utilize the structural and surface advantages of this carrier to construct a highly efficient photoelectric-driven microbial hybrid system, providing a new solution for enhancing microbial metabolism.

[0006] One object of the present invention is to provide a microbial photoelectric carrier, the microbial photoelectric carrier comprising a photoelectric carrier and a functional bacterial biofilm grown in situ on the surface of the photoelectric carrier; The photoelectric carrier is ITO conductive glass with polystyrene microspheres coated on its surface; The polystyrene microspheres are loaded with semiconductor nanoparticles and ITO nanoparticles.

[0007] Furthermore, the semiconductor nanoparticles are selected from one or more of cadmium sulfide (CdS), lead sulfide (PbS), ferrous sulfide (FeS2), molybdenum sulfide (MoS2), and titanium dioxide (TiO2).

[0008] Furthermore, the functional bacteria are selected from one or more of the following: Shewanella, Thiobacillus thioreducingus, Methanococcus methanotroph, Thermomycosis pyridamus, Escherichia coli, Cyanobacteria, Vibrio natans, Rhodopseudomonas erythrosporum, Copper-loving bacteria, and Ethanolobacterium harbinii.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned microbial photoelectric carrier, the method comprising the following steps: S1. Preparation of a mixture of polystyrene microspheres loaded with semiconductor nanoparticles and ITO nanoparticles; S2. The polystyrene microsphere mixture is drop-coated onto ITO conductive glass and dried to obtain an intermediate product; S3. The intermediate product is calcined to obtain a photoelectric carrier; S4. Inoculate the functional bacteria into a culture medium containing the photoelectric carrier and culture them; S5. Once the biofilm growth on the surface of the photoelectric carrier is complete, the microbial photoelectric carrier is obtained.

[0010] Further, in step S1, the preparation of the polystyrene microsphere mixture loaded with semiconductor nanoparticles and ITO nanoparticles includes the following steps: S1-1. Semiconductor nanoparticles and ITO nanoparticles are dispersed in a solvent to obtain a dispersion; S1-2. Wash the polystyrene microspheres; S1-3. The dispersion is added to the washed polystyrene microspheres and ultrasonically reacted in an ice-water bath to obtain a polystyrene microsphere mixture loaded with semiconductor nanoparticles and ITO nanoparticles.

[0011] Further, in step S1-1, the solvent is a methanol-water mixture with a product ratio of 5-15:1.

[0012] Furthermore, in steps S1-2, the polystyrene microspheres have a particle size of 5-20 μm.

[0013] Furthermore, in step S2, the drop coating thickness is 40-50 μm.

[0014] Furthermore, in step S3, the calcination temperature is 450-550℃ and the time is 20-30 min.

[0015] Furthermore, in step S4, the optimal growth culture medium and growth temperature corresponding to the preferred bacterial strain are determined.

[0016] The present invention has the following beneficial effects: This invention constructs a microbial photoelectric carrier using indium tin oxide (ITO) conductive glass as a substrate and incorporating polystyrene microspheres. The interconnected porous structure of these microspheres allows for ample containment and permeation of bacteria, facilitating initial adhesion and long-term colonization. Simultaneously, the pore walls, composed of a mesoporous framework, exhibit excellent permeability to nutrients and metabolic products. This permeable scaffold structure effectively isolates bacterial colonies, preventing excessive local accumulation and ensuring sufficient material exchange, allowing a large number of bacteria to actively engage in metabolic activities. Furthermore, this invention loads semiconductor nanoparticles and ITO nanoparticles onto the polystyrene microspheres, giving the system excellent photosensitivity and conductivity. Energy can be harvested from sunlight or electrochemical systems for microbial photoelectric synthesis, electricity production, or cathodic reduction synthesis of valuable chemicals. Attached Figure Description

[0017] Figure 1 This is a SEM image of the cross-section of the microbial photoelectric carrier prepared in Example 1.

[0018] Figure 2The hydrogen yield and biomass of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are given.

[0019] Figure 3 The cathode current density is for Example 1 and Comparative Example 1. Detailed Implementation

[0020] To more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0021] The terms "preferred," "more preferred," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0022] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0023] Example 1 A microbial photoelectric carrier, the microbial photoelectric carrier comprising a photoelectric carrier and a functional bacterial biofilm grown in situ on the surface of the photoelectric carrier; The photoelectric carrier is ITO conductive glass with polystyrene microspheres coated on its surface; The polystyrene microspheres are loaded with semiconductor nanoparticles and ITO nanoparticles. The functional bacteria is Harbin ethanol-producing bacillus YUAN-3; The semiconductor nanoparticles are CdS nanoparticles.

[0024] The preparation method of the above-mentioned microbial photoelectric carrier includes the following steps: S1. Preparation of a mixture of polystyrene microspheres loaded with semiconductor nanoparticles and ITO nanoparticles: S1-1. 5 mg of CdS nanoparticles and 20 mg of ITO nanoparticles were dispersed in 70 μL of a mixed solvent of methanol and water (volume ratio 6:1) and ultrasonically dispersed for 3 h to obtain a dispersion. S1-2. Take 1 mL of polystyrene microsphere solution with a solid content of 2.5 wt% (purchased from Zhongke Keyou, particle size 10 μm), wash with water and methanol in sequence to remove surfactant, and filter to obtain washed polystyrene microspheres; S1-3. The dispersion is added to the washed polystyrene microspheres and sonicated in an ice-water bath for 30 min to obtain a polystyrene microsphere mixture loaded with semiconductor nanoparticles and ITO nanoparticles. S2. Take 5 μL of the polystyrene microsphere mixture, drop it onto ITO conductive glass, and dry it in air at room temperature for 30 min to obtain the intermediate product; S3. The intermediate product is placed in air and heated from room temperature to 500°C at a heating rate of 1°C / min, and calcined at a constant temperature for 20 min to obtain the photoelectric carrier. S4. Inoculate the functional bacterium Harbin ethanol-producing Bacillus YUAN-3 at a 10% inoculum into 50 mL of culture medium containing the aforementioned photoelectric carrier and incubate at 35°C. The culture medium consisted of: glucose 15 g / L, peptone 4 g / L, beef extract 2 g / L, yeast extract 1 g / L, sodium chloride 4 g / L, dipotassium hydrogen phosphate 1.5 g / L, magnesium chloride 0.1 g / L, trace element solution (magnesium sulfate heptahydrate 3 g / L, ferrous sulfate heptahydrate 0.1 g / L, zinc sulfate heptahydrate 0.1 g / L, boric acid 0.01 g / L, triacetic acid 1.5 g / L, calcium chloride dihydrate 0.1 g / L, sodium molybdate dihydrate 0.01 g / L, cobalt chloride hexahydrate 0.1 g / L, nickel chloride hexahydrate 0.024 g / L, sodium tungstate dihydrate 0.025 g / L, manganese sulfate monohydrate 0.5 g / L, potassium aluminum sulfate dodecahydrate 0.01 g / L, copper sulfate pentahydrate 0.01 g / L) 5 mL / L, and vitamin solution (cobalamin 0.01 g / L, vitamin C 0.025 g / L). (5 mL / L of the following: riboflavin 0.025 g / L, citric acid 0.02 g / L, pyridoxal 0.05 g / L, para-aminobenzoic acid 0.01 g / L, creatine 0.025 g / L) S5. Observe the growth of microorganisms attached to the surface of the photoelectric carrier under a microscope. If the bacteria aggregate and cover more than 40% of the microspheres and carrier surface in the field of view, it indicates that the biofilm growth on the surface of the photoelectric carrier is complete, and the microbial photoelectric carrier is obtained.

[0025] Figure 1 This is a SEM image of the cross-section of the microbial photoelectric carrier prepared in Example 1.

[0026] Example 2 A microbial photoelectric carrier, the difference between this embodiment and Example 1 is that the functional bacteria are replaced with copper-loving bacteria H16, the rest of the preparation method is the same.

[0027] Comparative Example 1 The difference between this comparative example and Example 1 is that there is no microbial composite, only a single photoelectric carrier (i.e., steps S4 and S5 are omitted).

[0028] Comparative Example 2 The difference between this comparative example and Example 1 is that in step S1, the ITO nanoparticles are replaced with insulating ZrO2.

[0029] Comparative Example 3 The difference between this comparative example and Example 1 is that step S1 is modified as follows: 1 mL of polystyrene microsphere solution with a solid content of 2.5 wt% (purchased from Zhongke Keyou, particle size 10 μm) is taken, washed with water and methanol in sequence to remove surfactant, filtered to obtain washed polystyrene microspheres, and dispersed in 70 μL of a mixed solvent of methanol and water (volume ratio 6:1) to obtain a polystyrene microsphere mixture (i.e., a polystyrene microsphere mixture without any load).

[0030] Test case Performance tests were performed on the examples and comparative examples.

[0031] At 1mW / cm 2 After 24 hours of light exposure, the performance and biomass of *Alternaria harzianum* YUAN-3 in producing hydrogen from glucose were assessed, as shown in the following results. Figure 2 As shown.

[0032] Figure 2 Hydrogen yield and biomass for Examples 1, 1, 2, and 3. From... Figure 2 As can be seen from a, the microbial photoelectric carrier has the highest hydrogen production rate under light irradiation, which indicates that the photoelectric carrier significantly promotes the metabolic activity of the microorganism Harbin ethanol-producing bacterium YUAN-3. Figure 2 b indicates that the biomass attached to the microbial photoelectric carrier is the highest. The conductive photoelectric carrier can generate photoelectrons under light and efficiently transfer these electrons to microorganisms, promoting their growth and proliferation. Insulating particles cannot transfer the photoelectrons generated by semiconductor nanoparticles, thus having limited effect on promoting microbial growth. Microbial carriers without any nanoparticle loading can only rely on organic substrates for slow metabolism, resulting in the lowest hydrogen production and biomass accumulation.

[0033] Figure 3 The current densities of Example 1 and Comparative Example 1 at a cathode potential of -0.4 V (vs SHE) are shown.

[0034] from Figure 3It can be seen that the microbial photoelectric carrier prepared in Example 1 exhibits a significantly higher cathode current density at the set potential, indicating that the microorganisms receive external electrons from the carrier surface, there is a good coupling interface between the microorganisms and the carrier, and the photoelectric carrier successfully transfers cathode electrons to the loaded microorganisms.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A microbial photoelectric carrier, characterized in that, The microbial photoelectric carrier includes a photoelectric carrier and a functional bacterial biofilm grown in situ on the surface of the photoelectric carrier; The photoelectric carrier is ITO conductive glass with polystyrene microspheres coated on its surface; The polystyrene microspheres are loaded with semiconductor nanoparticles and ITO nanoparticles.

2. The microbial photoelectric carrier according to claim 1, characterized in that, The semiconductor nanoparticles are selected from one or more of cadmium sulfide, lead sulfide, ferrous sulfide, molybdenum sulfide, and titanium dioxide.

3. The microbial photoelectric carrier according to claim 1, characterized in that, The functional bacteria are selected from one or more of the following: Shewanella, Thiobacillus thioreductoids, Methanococcus taeniorhynchus, Thermomycosis acetamipridae, Escherichia coli, Cyanobacteria, Vibrio natans, Rhodopseudomonas erythrosporum, Copper-loving bacteria, and Ethanolobacterium harbinii.

4. The method for preparing the microbial photoelectric carrier according to any one of claims 1-3, characterized in that, The preparation method of the microbial photoelectric carrier includes the following steps: S1. Preparation of a mixture of polystyrene microspheres loaded with semiconductor nanoparticles and ITO nanoparticles; S2. The polystyrene microsphere mixture is drop-coated onto ITO conductive glass and dried to obtain an intermediate product; S3. The intermediate product is calcined to obtain a photoelectric carrier; S4. Inoculate the functional bacteria into a culture medium containing the photoelectric carrier and culture them; S5. Once the biofilm growth on the surface of the photoelectric carrier is complete, the microbial photoelectric carrier is obtained.

5. The method for preparing the microbial photoelectric carrier according to claim 4, characterized in that, In step S1, the preparation of the polystyrene microsphere mixture loaded with semiconductor nanoparticles and ITO nanoparticles includes the following steps: S1-1. Semiconductor nanoparticles and ITO nanoparticles are dispersed in a solvent to obtain a dispersion; S1-2. Wash the polystyrene microspheres; S1-3. The dispersion is added to the washed polystyrene microspheres and ultrasonically reacted in an ice-water bath to obtain a polystyrene microsphere mixture loaded with semiconductor nanoparticles and ITO nanoparticles.

6. The method for preparing the microbial photoelectric carrier according to claim 5, characterized in that, In step S1-1, the solvent is a methanol-water mixture with a product ratio of 5-15:

1.

7. The method for preparing the microbial photoelectric carrier according to claim 5, characterized in that, In steps S1-2, the polystyrene microspheres have a particle size of 5-20 μm.

8. The method for preparing the microbial photoelectric carrier according to claim 4, characterized in that, In step S2, the drop coating thickness is 40-50 μm.

9. The method for preparing the microbial photoelectric carrier according to claim 4, characterized in that, In step S3, the calcination temperature is 450-550℃ and the time is 20-30 min.

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