Bi / BiVO4-based photoelectrochemical sensing platform and its bacterial detection and inactivation method

Abstract

The application provides a kind of Bi / BiVO4-based photoelectrochemical sensing platform and its bacterial detection and inactivation method, it is related to photoelectrochemical biological detection technical field, the photoelectrochemical sensing platform includes Bi / BiVO4 composite material, it includes BiVO4 matrix and metal Bi reduced in situ on the surface of BiVO4 matrix, for generating photocurrent signal under visible light irradiation, and with peroxidase-like activity.Detection, target bacteria release endogenous cysteine desulfurase, catalyze L-cysteine to produce H2S, and generate Bi2S3 heterojunction with Bi / BiVO4 in situ, realize bacterial quantitative detection by photocurrent change;Inactivation, use peroxidase-like activity to catalyze H2O2 to produce ROS to kill bacteria.The photoelectrochemical sensing platform effectively inhibits carrier recombination by in-situ reduction of metal Bi, improves photoelectric conversion efficiency, and realizes detection and inactivation integration.

Description

Technical Field

[0001] This invention relates to the field of photoelectrochemical biological detection technology, specifically to a photoelectrochemical sensing platform based on Bi / BiVO4 and its bacterial detection and inactivation method. Background Technology

[0002] Foodborne pathogens (such as Staphylococcus aureus, Escherichia coli, and Escherichia coli) pose a significant threat to global public health and food safety. Because pathogens typically reside in complex matrices, traditional detection methods (such as plate culture counting and biochemical identification) are cumbersome and time-consuming, making them unsuitable for rapid on-site detection. While antibody- or aptamer-based biosensors offer high sensitivity, they suffer from limitations such as high receptor costs, susceptibility to inactivation, and complex sample pretreatment processes.

[0003] Photoelectrochemical (PEC) biosensors possess unique advantages such as low background noise, high detection sensitivity, and simple equipment due to the spatial separation between the excitation source and the detection signal. However, highly sensitive quantitative detection of pathogens directly in complex real-world samples still faces significant challenges. Most pathogens are rich in specific endogenous enzymes, such as cysteine ​​desulfurases (CDes), which are widely present in various pathogens. Utilizing lysis buffers to release endogenous CDes from within bacteria, which specifically catalyze the decomposition of the substrate L-cysteine ​​(L-Cys) to generate hydrogen sulfide (H2S), can convert bacterial concentration into a chemical signal without the need for complex biointerface receptor modification and immobilization steps. However, current technical solutions for rapid detection of foodborne pathogens using the specific gas-generating mechanism of endogenous CDes combined with a highly efficient PEC sensing interface have not yet been effectively applied.

[0004] Furthermore, the photoelectric conversion efficiency of photoactive materials is the core factor determining the analytical performance of PEC sensors. Bismuth vanadate (BiVO4), as a semiconductor photoelectrode material, has attracted much attention due to its narrow band gap and good visible light response. However, BiVO4 suffers from drawbacks such as high carrier recombination rate, low electronic conductivity, and slow surface catalytic kinetics, which severely limit its sensitivity and stability in PEC biosensing. Meanwhile, most existing biosensor platforms are single-function and lack an integrated design that can simultaneously achieve highly sensitive detection and effective removal of target pathogens. Summary of the Invention

[0005] To address the technical problems mentioned above, this invention provides a photoelectrochemical sensing platform based on Bi / BiVO4 and a method for bacterial detection and inactivation thereof.

[0006] The first aspect of the present invention provides a photoelectrochemical sensing platform based on Bi / BiVO4, comprising: Bi / BiVO4 composite material, comprising a BiVO4 matrix and metallic Bi reduced in situ to the surface of the BiVO4 matrix; The Bi / BiVO4 composite material is used to generate a photocurrent signal under visible light irradiation, and the Bi / BiVO4 composite material has peroxidase-like activity.

[0007] Furthermore, the Bi / BiVO4 composite material has a polyhedral structure and its surface is rich in oxygen vacancy defects.

[0008] Furthermore, the Bi / BiVO4 composite material has a decahedral structure, and the material interface has a Bi-OV covalent bridging structure.

[0009] Furthermore, the Bi / BiVO4 composite material is loaded onto a conductive substrate to form a photoelectrode.

[0010] Furthermore, the conductive substrate is ITO conductive glass.

[0011] A second aspect of the present invention provides a method for bacterial detection based on the photoelectrochemical sensing platform described in the first aspect of the present invention, comprising: Lysing the target bacteria and releasing the endogenous cysteine ​​desulfurization enzymes inside the bacteria; The obtained lysate containing endogenous cysteine ​​desulfurization enzyme was mixed with the substrate L-cysteine, and the Bi / BiVO4 photoelectrode was immersed in the mixture and incubated at 30-42°C. The endogenous cysteine ​​desulfurization enzyme catalyzed the decomposition of L-cysteine ​​to produce H2S gas. The H2S gas reacted in situ with Bi / BiVO4 on the surface of the Bi / BiVO4 photoelectrode to generate Bi2S3, forming a Bi2S3 / Bi / BiVO4 heterojunction. Using the modified photoelectrode as the working electrode, the photocurrent response signal is measured under visible light irradiation, and the concentration of the target bacteria is quantitatively detected based on the change in photocurrent intensity.

[0012] Furthermore, the incubation temperature is 37°C, and the incubation time is 2-4 hours.

[0013] Furthermore, the target bacteria are Staphylococcus aureus or Escherichia coli; when the target bacteria are Staphylococcus aureus, lysozyme is used for lysis; when the target bacteria are Escherichia coli, Escherichia coli phage is used for lysis.

[0014] Furthermore, the preparation method of the Bi / BiVO4 photoelectrode includes: synthesizing a monoclinic phase BiVO4 precursor using a one-step hydrothermal method, followed by calcination at 400-500℃ for 1-3 hours in a N2 / H2 reducing atmosphere to partially reduce the surface of BiVO4 to metallic Bi in situ, thereby obtaining a Bi / BiVO4 composite material, which is then loaded onto a conductive substrate to form a photoelectrode.

[0015] A third aspect of the present invention provides a method for bacterial inactivation based on the photoelectrochemical sensing platform described in the first aspect of the present invention, comprising: mixing the Bi / BiVO4 composite material with a sample containing target bacteria and H2O2, and utilizing the peroxidase-like activity of the Bi / BiVO4 composite material to catalyze the generation of ROS from H2O2, thereby killing the target bacteria.

[0016] Compared with existing technologies, this invention provides a photoelectrochemical sensing platform based on Bi / BiVO4 and its bacterial detection and inactivation method. Metallic Bi is in situ reduced to its original state on the BiVO4 surface through calcination in a reducing atmosphere, forming a tight interfacial contact between the metallic Bi and BiVO4. On one hand, metallic Bi acts as an electron acceptor and a fast transport channel, effectively capturing photogenerated electrons from BiVO4 and accelerating their migration to the electrode surface, significantly suppressing bulk carrier recombination. On the other hand, oxygen vacancy defects introduced during the reduction process form defect energy levels in the BiVO4 band gap, broadening the visible light absorption range and increasing the photogenerated carrier density. These two factors work synergistically to achieve efficient spatial separation of photogenerated electron-hole pairs, significantly enhancing the photocurrent response signal. This solves the technical problem of low detection sensitivity caused by severe carrier recombination in traditional BiVO4. Furthermore, this composite material can be used directly for detection without additional modification of biometric elements, simplifying the construction process of the sensing platform. Attached Figure Description

[0017] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0018] Figure 1 This is a schematic diagram of the construction and detection principle of the photoelectrochemical sensing platform provided in Embodiment 1 of the present invention, wherein A is a schematic diagram of the mechanism of bacterial lysis releasing CDes and catalyzing L-Cys to generate H2S; B is a schematic diagram of the PEC response of Bi / BiVO4 under different test conditions; and C is a schematic diagram of the bactericidal mechanism of Bi / BiVO4. Figure 2 The X-ray diffraction (XRD) patterns of BiVO4 and Bi / BiVO4 provided in Embodiment 1 of the present invention; Figure 3The UV-Vis diffuse reflectance absorption spectra of BiVO4 and Bi / BiVO4 provided in Embodiment 1 of the present invention; Figure 4 The photoluminescence (PL) spectra of BiVO4 and Bi / BiVO4 provided in Embodiment 1 of the present invention; Figure 5 Scanning electron microscope (SEM) images and elemental mapping images of BiVO4 and Bi / BiVO4 provided in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram showing the preparation process and morphology of the Bi / BiVO4 composite material provided in Embodiment 1 of the present invention; Figure 7 This is a cyclic voltammetry curve analysis diagram of the sensor interface construction process provided in Embodiment 2 of the present invention; Figure 8 The experimental condition optimization diagram (temperature and incubation time) of the PEC biosensor provided in Embodiment 2 of the present invention is shown. Figure 9 The above is a graph showing the analytical performance of the PEC biosensor provided in Embodiment 2 of the present invention. A is the linear range of S. aureus detection, B is the S. aureus regression curve, C is the linear range of E. coli detection, and D is the E. coli calibration curve. Figure 10 This is a stability and reproducibility test diagram of the PEC biosensor provided in Embodiment 2 of the present invention; Figure 11 The linear regression curves for the quantitative detection of S. aureus and E. coli by the PEC biosensor provided in Embodiment 2 of the present invention are shown. Figure 12 This is an evaluation diagram of the enzyme-like catalytic activity of BiVO4 and Bi / BiVO4 provided in Example 3 of the present invention. Detailed Implementation

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms "comprising," "having," and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0022] All data acquisition in this embodiment is carried out in accordance with laws and regulations and with user consent, and the data is used legally.

[0023] Example 1 This embodiment provides a photoelectrochemical sensing platform based on Bi / BiVO4. The sensing platform includes a Bi / BiVO4 composite material, which includes a BiVO4 matrix and metallic Bi reduced in situ on the surface of the BiVO4 matrix. The Bi / BiVO4 composite material is used to generate a photocurrent signal under visible light irradiation, and the Bi / BiVO4 composite material has peroxidase-like activity.

[0024] The Bi / BiVO4 composite material has a polyhedral structure and its surface is rich in oxygen vacancy defects; preferably, the Bi / BiVO4 composite material has a decahedral structure and the material interface has a Bi-OV covalent bridging structure. The Bi / BiVO4 composite material is loaded on a conductive substrate to form a photoelectrode; preferably, the conductive substrate is ITO conductive glass.

[0025] like Figure 1 The diagram shows the construction and detection principle of the photoelectrochemical (PEC) biosensor platform. A represents the lysis process of *S. aureus* and *E. coli* under the specific action of lysin and *E. coli* phage, respectively; B represents the PEC signal response of Bi / BiVO4 in blank, L-Cys, Bly, and the coexistence of L-Cys and Bly, respectively; C represents the efficient removal of bacteria by Bi / BiVO4 using ROS generated by its excellent peroxidase-like activity.

[0026] In this embodiment, the Bi / BiVO4 composite material is prepared by the following method: Weigh 5 M Bi(NO3)3·5H2O and dissolve it in 15 mL of 2 M NaOH solution. Stir magnetically for 0.5 h to obtain mixed solution 1. Weigh 5 M NH4VO3 and dissolve it in 15 mL of 2 M HNO3 solution. Stir magnetically for 0.5 h to obtain mixed solution 2. Solution 1 was slowly added dropwise to solution 2, and the mixture was continuously stirred magnetically for 2 hours to obtain a homogeneous precursor reaction solution. The above precursor reaction solution was transferred to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene, sealed, and placed in an oven at 180°C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged to collect the precipitate, washed three times with ultrapure water, and dried in a vacuum drying oven at 60°C to obtain a pale yellow monoclinic BiVO4 powder. Take 500 mg of the dried BiVO4 powder and place it in a tube furnace. Introduce a N2 / H2 reducing atmosphere. Heat the furnace to 450°C at a heating rate of 5°C / min and calcine for 2 h to induce a localized thermal reduction reaction. After the reaction is complete, the furnace is cooled to room temperature to obtain a Bi / BiVO4 composite material with a polyhedral decahedral structure, rich in oxygen vacancies on the surface, and a Bi-OV covalent bridging structure.

[0027] like Figure 2 As shown, the X-ray diffraction (XRD) pattern shows that the diffraction peaks of the original BiVO4 are completely matched with the standard card of monoclinic BiVO4 (JCPDS 83-1699); while the reduced Bi / BiVO4 composite material shows new diffraction peaks at 2θ of 27.16°, 37.95° and 39.62°, which are attributed to the (012), (104) and (110) crystal planes of metallic Bi, respectively, confirming the successful in-situ reduction of metallic Bi on the BiVO4 surface, that is, the Bi / BiVO4 composite material has the composition structure of BiVO4 matrix and metallic Bi in-situ reduced to the surface of BiVO4 matrix.

[0028] like Figure 3As shown, the optical absorption characteristics and band structure of pure BiVO4 and the Bi / BiVO4 composite material prepared by in-situ reduction were compared and analyzed using ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Compared with the original BiVO4, the Bi / BiVO4 composite material with in-situ growth of metallic Bi on the surface showed a significant increase in absorption intensity in the visible light band (approximately 400–800 nm), and its optical absorption band edge exhibited a significant redshift. These changes in spectral characteristics confirm that the in-situ introduction of metallic Bi and the oxygen vacancy defects generated during the reduction process effectively optimized the electronic structure of the material and broadened its visible light response range. The synergistic improvement in the light absorption range and light absorption efficiency significantly enhanced the photoelectrode material's ability to capture incident photons, thereby promoting the efficient separation and interface transfer of photogenerated electron-hole pairs under illumination, providing sufficient photogenerated carriers for the subsequent highly sensitive PEC signal response at the electrochemical interface.

[0029] like Figure 4 As shown, under excitation light irradiation, the pure-phase BiVO4 material exhibits a strong characteristic fluorescence emission peak at a wavelength of 550 nm, which originates from the high-rate radiative recombination of photogenerated electrons and holes within it. In contrast, the PL emission peak intensity of the Bi / BiVO4 composite material with surface-modified metallic Bi shows significant fluorescence quenching at this wavelength. The establishment of this charge channel effectively blocks the bound recombination path of photogenerated carriers, significantly prolonging the carrier lifetime and achieving efficient spatial separation and rapid interfacial transfer of photogenerated electron-hole pairs. This optimization of the microscopic dynamic process provides direct physical mechanism support for the generation of high-density photocurrent and highly sensitive electrochemical sensing signals by the photoelectrode material of this invention under illumination.

[0030] like Figure 5 As shown, the morphology and elemental distribution of BiVO4 and Bi / BiVO4 composites were characterized using scanning electron microscopy (SEM) and elemental mapping. The left side of the image represents BiVO4, and the right side represents Bi / BiVO4. The scale bar for BiVO4 is 500 nm, showing multiple stacked plate-like or polyhedral particles; the scale bar for Bi / BiVO4 is 1 μm, showing multiple aggregated polyhedral or blocky particles. The corresponding elemental mapping diagrams for Bi, O, and V show that Bi, O, and V elements are uniformly distributed in both materials, and the elemental mapping regions basically correspond to the particle morphology.

[0031] like Figure 6The diagram shows the preparation process and morphology of the Bi / BiVO4 composite material. Part A shows the preparation process of BiVO4 formed by hydrothermal reaction of Bi(NO3)3·5H2O and NH4VO3 precursors at 180℃ for 24 h, followed by reduction calcination with N2 / H2 to form Bi / BiVO4. Parts B and C are the particle morphology diagrams of BiVO4 and Bi / BiVO4, respectively, with a scale bar of 500 nm. It can be seen that BiVO4 particles have a nearly circular or polyhedral morphology, while Bi / BiVO4 particles exhibit a polyhedral morphology with clearer edges and corners after reduction calcination.

[0032] The polyhedral decahedral Bi / BiVO4 formed by the reduction and calcination of the aforementioned sensing platform possesses a "Bi-OV" covalent bridge structure and is rich in oxygen vacancies, which significantly reduces the charge transfer resistance (Rct) and significantly improves the photoelectric conversion and carrier separation efficiency, solving the technical problem of low detection sensitivity caused by severe carrier recombination in traditional BiVO4. At the same time, the Bi / BiVO4 composite material also has peroxidase-like activity, enabling it to perform photoelectrochemical detection while also possessing catalytic bactericidal ability, providing a material basis for the integration of detection and inactivation.

[0033] Example 2 This embodiment provides a bacterial detection method based on the photoelectrochemical sensing platform provided in Embodiment 1.

[0034] This detection method is based on the gas production mechanism of endogenous cysteine ​​desulfurase (CDes): target bacteria are lysed using a specific lysing agent to release endogenous CDes from within the bacteria; the bacterial lysate, substrate L-cysteine ​​(L-Cys), and Bi / BiVO4 photoelectrode are co-incubated at an optimal temperature of 37℃ for 3 h, where CDes catalyze L-Cys to produce highly active H2S gas; H2S reacts in situ with metallic Bi and BiVO4 on the electrode surface to generate Bi2S3, constructing a Bi2S3 / Bi / BiVO4 heterojunction with highly efficient charge separation performance, resulting in a significant enhancement of the PEC photocurrent signal, enabling quantitative detection of the target bacterial concentration.

[0035] The method for culturing and preparing pathogenic bacteria is as follows: Dissolve 2.0 g of sodium chloride, 2.0 g of tryptone and 1.0 g of yeast powder in 200 mL of ultrapure water. After sonication-assisted dissolution, autoclave at 120℃ for 30 min. Under aseptic conditions, 200 μL of Escherichia coli or Staphylococcus aureus was inoculated into 50 mL of sterile LB medium and cultured overnight in a constant temperature shaker at 37°C and 140 rpm. The bacterial culture was centrifuged at 5000 rpm for 3 min, the supernatant was discarded, and the bacterial sludge was resuspended in 10 mM PBS (pH 7.4). The centrifugation and washing were repeated 3 times. The absorbance (OD) of the bacterial suspension at 600 nm was measured using a UV-Vis spectrophotometer. 600 ), with OD 600 =0.1 (corresponding to a bacterial concentration of 10) 8 The bacterial concentration was calibrated using CFU / mL as a baseline and combined with plate count method.

[0036] The preparation method of pathogenic bacteria lysate is as follows: Mix 200 μL of lysin with 8 mL of S. aureus bacterial suspension of different concentrations, and incubate at 18 rpm for 1.5 h in a shaker at 37℃. After incubation, centrifuge at 6000 rpm to collect the supernatant, which is the S. aureus lysate containing endogenous cysteine ​​desulfurization enzyme (CDes). 200 μL of Escherichia coli phage was mixed with 5 mL of E. coli bacterial suspension of different concentrations and incubated in a shaker at 37℃ with shaking at 18 rpm for 3 h. After the reaction was completed, the supernatant was collected by centrifugation at 6000 rpm to obtain E. coli lysate containing endogenous CDes.

[0037] The construction of the PEC sensing platform and the method for detecting pathogens are as follows: The Bi / BiVO4 composite material prepared in Example 1 was quantitatively drop-coated onto a clean ITO conductive glass surface and dried to form a Bi / BiVO4 photoelectrode. The substrate L-cysteine ​​(L-Cys) was mixed with the bacterial lysis buffer (containing CDes) prepared above, and the Bi / BiVO4 photoelectrode was immersed in the mixture and co-incubated at the optimal temperature of 37℃ for 3 h. CDes catalyzed the decomposition of L-Cys to generate highly active H2S gas. H2S reacted in situ with Bi / BiVO4 on the photoelectrode surface to generate Bi2S3, thus constructing a Bi2S3 / Bi / BiVO4 heterojunction with high electron transport efficiency. Using modified ITO as the working electrode, a standard three-electrode system was employed to measure the photocurrent response signal under visible light irradiation. The concentration of the target pathogenic bacteria was quantitatively detected based on the change in photocurrent intensity.

[0038] like Figure 7As shown, the cyclic voltammetry analysis of the sensing interface construction process shows that, compared with the bare ITO electrode, the redox peak current of the electrode modified with Bi / BiVO4 is significantly reduced; and after further reaction with bacterial lysate and L-Cys to generate Bi2S3, the peak current is enhanced again, indicating that the formed Bi2S3 / Bi / BiVO4 heterojunction significantly promotes electron transport at the electrode interface.

[0039] like Figure 8 As shown, impedance analysis during the sensor interface construction process reveals that the electron transfer resistance (Rct) of the Bi / BiVO4 electrode is higher than that of the bare ITO electrode; however, after the formation of the Bi2S3 / Bi / BiVO4 heterojunction, Rct decreases significantly, further confirming that the heterostructure can significantly reduce the charge transfer resistance.

[0040] like Figure 9 As shown, the PEC response and sensing mechanism during the sensor interface construction process reveal that bare ITO exhibits no visible light response; Bi / BiVO4 displays a basic photocurrent signal; the photocurrent slightly increases when Bi / BiVO4 is incubated alone with L-Cys, attributed to the effect of a small amount of thiol groups; the photocurrent increases when Bi / BiVO4 is incubated alone with bacterial lysate, attributed to the effect of trace amounts of H2S carried by the bacteria; when Bi / BiVO4, L-Cys, and bacterial lysate are incubated together, the photocurrent shows an explosive increase. This phenomenon demonstrates that CDes released by bacterial lysis can efficiently catalyze the decomposition of L-Cys to release a large amount of H2S, and the in-situ generated Bi2S3 forms a synergistic heterojunction with Bi / BiVO4, significantly improving the separation efficiency of photogenerated carriers.

[0041] like Figure 10 As shown, key parameters of the sensor incubation process were optimized. Under a fixed incubation time, the effects of different temperatures (27°C, 32°C, 37°C, 42°C) on the PEC signal were evaluated. The photocurrent initially increased and then decreased with increasing temperature, reaching a peak at 37°C, indicating that CDes enzyme activity was highest at this temperature; therefore, 37°C was selected as the optimal incubation temperature. At 37°C, the photocurrent increased with prolonged incubation time, and the increase tended to plateau after 3 hours (signal differences at 3 hours, 4 hours, and 5 hours were minimal). Considering both detection sensitivity and efficiency, the optimal incubation time was determined to be 3 hours.

[0042] like Figure 11 As shown, the performance of the PEC sensing platform for quantitative analysis of *S. aureus* and *E. coli* was evaluated under optimal conditions. For *S. aureus*, the performance was evaluated within the range of 10¹ to 10¹⁰. 8 Within the CFU / mL concentration range, the photocurrent intensity (I) showed a good linear relationship with the logarithm of S. aureus concentration, and the linear regression equation was: I= 0.2914 lg c S.aureus + 0.6336 ( R 2 = 0.9942), and the limit of detection (LOD) for *S. aureus* calculated using the 3σ method was as low as 3.5 CFU / mL. Furthermore, the limit of detection for *E. coli* was within the range of 10¹ to 10¹⁰. 8 Within the CFU / mL concentration range, the photocurrent intensity showed a good linear relationship with the logarithm of E. coli concentration, and the linear regression equation was: I = 0.2545 lg c E.coli + 0.6934 ( R 2 = 0.9937), which yielded a LOD of as low as 4.1 CFU / mL for E. coli.

[0043] The above detection method is simple to operate and does not require immobilized receptors. It abandons the traditional antibody / aptamer immobilization process and uses the mechanism of endogenous CDes enzymes catalyzing the substrate to produce H2S in the liquid phase after bacterial lysis for indirect sensing. This effectively reduces matrix interference and preparation costs, and significantly improves detection reproducibility.

[0044] Example 3 This embodiment provides a bacterial inactivation method based on the photoelectrochemical sensing platform provided in Embodiment 1.

[0045] This inactivation method utilizes the oxygen vacancies and heterojunction structure introduced by reduction calcination to endow Bi / BiVO4 with excellent peroxidase-like (POD-like) catalytic activity; in the presence of trace amounts of H2O2, this material can efficiently catalyze the generation of a large number of reactive oxygen species (ROS), thereby achieving efficient and thorough killing of pathogenic bacteria.

[0046] like Figure 12As shown, 3,3',5,5'-tetramethylbenzidine (TMB) was used as the chromogenic substrate. The enzyme-like (peroxidase-like and oxidase-like) catalytic activities of the original BiVO4 and the in-situ reduced Bi / BiVO4 composite material were systematically evaluated using UV-Vis absorption spectroscopy. In Figure A, after incubation with the test material in a reaction system containing TMB substrate and a trace amount of hydrogen peroxide (H2O2), the system exhibited a significant characteristic absorption peak at 652 nm, indicating that the colorless TMB was successfully catalytically oxidized to a blue oxidized product (oxTMB). Comparative experiments showed that the absorbance response of the Bi / BiVO4 composite material at 652 nm was significantly higher than that of the original BiVO4, indicating superior peroxidase-like activity. B indicates that in the colorimetric system without the addition of H2O2 (containing only TMB and dissolved oxygen), the Bi / BiVO4 composite material can still induce a clear oxTMB absorption peak at 652 nm, confirming that the composite material also possesses endogenous oxidase-like activity that can directly activate dissolved oxygen without the addition of external peroxides.

[0047] The above-mentioned inactivation method realizes the integrated detection and elimination functions of diagnosis / treatment and protection. The material prepared by the invention has both photoelectric response capability and peroxidase-like activity. While achieving detection with extremely low detection limits, it can catalyze the generation of a large amount of ROS to kill pathogens, providing a new approach for building a multifunctional high-throughput pathogen sensing and control platform.

[0048] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A photoelectrochemical sensing platform based on Bi / BiVO4, characterized in that, include: Bi / BiVO4 composite material, comprising a BiVO4 matrix and metallic Bi reduced in situ to the surface of the BiVO4 matrix; The Bi / BiVO4 composite material is used to generate a photocurrent signal under visible light irradiation, and the Bi / BiVO4 composite material has peroxidase-like activity.

2. The photoelectrochemical sensing platform according to claim 1, characterized in that, The Bi / BiVO4 composite material has a polyhedral structure and its surface is rich in oxygen vacancy defects.

3. The photoelectrochemical sensing platform according to claim 2, characterized in that, The Bi / BiVO4 composite material has a decahedral structure and the material interface has a Bi-OV covalent bridging structure.

4. The photoelectrochemical sensing platform according to claim 1, characterized in that, The Bi / BiVO4 composite material is loaded onto a conductive substrate to form a photoelectrode.

5. The photoelectrochemical sensing platform according to claim 4, characterized in that, The conductive substrate is ITO conductive glass.

6. A method for detecting bacteria based on the photoelectrochemical sensing platform according to any one of claims 1 to 5, characterized in that, include: Lysing the target bacteria and releasing the endogenous cysteine ​​desulfurization enzymes inside the bacteria; The obtained lysate containing endogenous cysteine ​​desulfurization enzyme was mixed with the substrate L-cysteine, and the Bi / BiVO4 photoelectrode was immersed in the mixture and incubated at 30-42°C. The endogenous cysteine ​​desulfurization enzyme catalyzed the decomposition of L-cysteine ​​to produce H2S gas. The H2S gas reacted in situ with Bi / BiVO4 on the surface of the Bi / BiVO4 photoelectrode to generate Bi2S3, forming a Bi2S3 / Bi / BiVO4 heterojunction. Using the modified photoelectrode as the working electrode, the photocurrent response signal is measured under visible light irradiation, and the concentration of the target bacteria is quantitatively detected based on the change in photocurrent intensity.

7. The bacterial detection method according to claim 6, characterized in that, The incubation temperature is 37°C, and the incubation time is 2-4 hours.

8. The bacterial detection method according to claim 6, characterized in that, The target bacteria are Staphylococcus aureus or Escherichia coli; when the target bacteria are Staphylococcus aureus, lysozyme is used for lysis; when the target bacteria are Escherichia coli, Escherichia coli phage is used for lysis.

9. The bacterial detection method according to claim 6, characterized in that, The preparation method of the Bi / BiVO4 photoelectrode includes: synthesizing a monoclinic phase BiVO4 precursor by a one-step hydrothermal method, followed by calcination at 400-500℃ for 1-3 hours in a N2 / H2 reducing atmosphere to reduce the surface of BiVO4 to metallic Bi in situ, thereby obtaining a Bi / BiVO4 composite material, which is then loaded onto a conductive substrate to form a photoelectrode.

10. A method for bacterial inactivation based on the photoelectrochemical sensing platform according to any one of claims 1 to 5, characterized in that, include: The Bi / BiVO4 composite material is mixed with a sample containing target bacteria and H2O2. The peroxidase-like activity of the Bi / BiVO4 composite material is used to catalyze the production of ROS from H2O2, thereby killing the target bacteria.

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