Preparation method of black phosphorus / molybdenum disulfide nanoflower composite and application thereof in detection of foodborne pathogenic bacteria

Abstract

The application discloses a preparation method of black phosphorus / molybdenum disulfide nanoflower composite materials and application of the black phosphorus / molybdenum disulfide nanoflower composite materials in detection of foodborne pathogenic bacteria, and has the characteristics that the preparation method comprises the following steps: (1) black phosphorus nanosheets are prepared by using a hierarchical centrifugation assisted liquid phase exfoliation method; and (2) the black phosphorus / molybdenum disulfide nanoflower composite materials are prepared by using a hydrothermal method: 10 ml of the black phosphorus nanosheet aqueous solution prepared in the step (1), 5 ml of an ammonium molybdate aqueous solution and 5 ml of a thiourea aqueous solution are sequentially transferred into a polytetrafluoroethylene-lined stainless steel autoclave, the mixture is allowed to react at 200 DEG C for 24 hours after ultrasonic treatment, and then the black phosphorus / molybdenum disulfide nanoflower composite materials are obtained by washing with ethanol and deionized water several times, and can be used for detection of foodborne pathogenic bacteria and preparation of antibacterial agents, and the black phosphorus / molybdenum disulfide nanoflower composite materials have the advantages that the detection sensitivity of the foodborne pathogenic bacteria is improved, and the black phosphorus / molybdenum disulfide nanoflower composite materials have the functions of photothermal and photocatalytic synergistic antibacterial.

Description

Technical Field

[0001] The present invention relates to a molybdenum disulfide nanoflower composite material, and in particular to a preparation method of a black phosphorus / molybdenum disulfide nanoflower composite material and application thereof in foodborne pathogen detection. Background Art

[0002] Foodborne diseases caused by foodborne pathogens, including Escherichia coli, Staphylococcus aureus, Salmonella enterica, Campylobacter jejuni, etc., can cause serious illness in humans. Rapid detection and differentiation of foodborne bacteria are becoming increasingly important in ensuring food safety. Current bacterial detection methods mainly rely on conventional culture identification strategies, immunoassay technology, and polymerase chain reaction. Traditional culture methods are time-consuming and labor-intensive. Immunoassay methods are rapid and sensitive and can simplify the process of bacterial identification, but the method is complex to operate and has low selectivity. PCR-based detection can detect specific bacterial DNA in a timely and simple manner, but it is limited by background interference. Therefore, it is necessary to explore a faster and more sensitive bacterial identification method.

[0003] Surface-enhanced Raman scattering (SERS), a versatile fingerprint analysis method, has attracted widespread attention for its high sensitivity, strong specificity, simple analysis, and non-destructive nature. Currently, SERS-based detection of foodborne pathogens typically utilizes two methods: labeled indirect detection and label-free direct detection. Compared to indirect detection, label-free direct detection is simpler, more stable, and offers higher accuracy.

[0004] The emerging two-dimensional (2D) material black phosphorus (BP) has become one of the most promising materials in biomedicine, electronics, and optoelectronics due to its high biocompatibility, remarkable electronic conductivity, layer-dependent direct band gap ranging from 0.3 eV in bulk to 2.0 eV in monolayers, and particularly its broad absorption band from the ultraviolet to the near-infrared region. Furthermore, rosette-shaped molybdenum disulfide (MoS2) nanoflowers possess a band gap suitable for visible light, strong near-infrared photothermal absorption, excellent stability, and biocompatibility. Their large surface area is filled with active electrons and functional groups, which enable therapeutic and diagnostic applications and have attracted significant attention in biomedicine, electronics, and optoelectronics. Currently, there are no published reports on the use of black phosphorus / MoS2 nanoflower composites for detecting foodborne pathogens. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method of a black phosphorus / molybdenum disulfide nanoflower composite material which improves the sensitivity of foodborne pathogen detection and has synergistic antibacterial functions of photothermal and photocatalytic properties, and its application in foodborne pathogen detection.

[0006] The technical scheme adopted by the present application to solve the above technical problems is: a preparation method of black phosphorus / molybdenum disulfide nanoflower composite material, comprising the following steps:

[0007] (1) Adopting hierarchical centrifugal assisted liquid phase exfoliation method to prepare black phosphorus nanosheet

[0008] The black phosphorus is added into deionized water to prepare a 1 mg / ml black phosphorus solution, then the dissolved oxygen in the liquid is removed by argon bubbling, and after ultrasonic treatment at 5℃ for 4 hours, the dark brown precipitate is collected after centrifugation at 3000 rpm for 15 minutes, after removing the light brown liquid, the collected dark brown precipitate is washed with deionized water and ethanol for 2-4 times, and after vacuum drying at 60℃ for 12 hours, the black phosphorus nanosheet is obtained;

[0009] (2) Adopting hydrothermal method to prepare black phosphorus / molybdenum disulfide nanoflower composite material

[0010] The black phosphorus nanosheet prepared in step (1) is added into deionized water, and the black phosphorus nanosheet aqueous solution is obtained after ultrasonic treatment for 8-12 minutes; the black phosphorus nanosheet aqueous solution, ammonium molybdate aqueous solution and thiourea aqueous solution are mixed in a volume ratio of 2:1:1, and then placed in a polytetrafluoroethylene-lined stainless steel autoclave for ultrasonic treatment for 10 minutes, and heated to 200℃, and kept for 24 hours, then centrifuged, and the black precipitate obtained by centrifugation is washed with deionized water and ethanol for 2-4 times, and vacuum dried at 60℃ for 12 hours to obtain the black phosphorus / molybdenum disulfide nanoflower composite material.

[0011] Further, the concentration of the black phosphorus nanosheet aqueous solution in step (3) is 1.8-2.2 mg / ml.

[0012] Further, the concentration of the ammonium molybdate aqueous solution in step (3) is 1.4-6 mg / ml.

[0013] Further, the concentration of the thiourea aqueous solution in step (3) is 3.04-13.03 mg / ml.

[0014] The method for detecting foodborne pathogenic bacteria prepared by the black phosphorus / molybdenum disulfide nanoflower composite material has the characteristics that the method is not for the purpose of diagnosis or treatment, and comprises the following steps: adding the black phosphorus / molybdenum disulfide nanoflower composite material into a to-be-detected solution containing foodborne pathogenic bacteria at a mass-volume ratio of 1 mg:100 microliters, oscillating, then incubating with a rotary oscillator at 250 rpm for 4.5 hours, then washing the black phosphorus / molybdenum disulfide nanoflower solution with bacteria adhered thereto twice with deionized water, dispersing the collected precipitate in 500 microliters of deionized water, dropping 10 microliters of the mixed liquid on a 0.5*0.5 silicon wafer, drying at 60 DEG C, then performing spectrum measurement by using a Raman spectrometer, detecting Raman signals, and calculating the concentration of foodborne pathogenic bacteria in the to-be-detected solution according to the linear relationship between the foodborne pathogenic bacteria and the Raman intensity.

[0015] Further, the Raman spectrometer adopts a 532nm semiconductor laser as an excitation source, the laser spot diameter is 12.5 microns, the numerical aperture is 0.55, the laser power is set to 1 mw, and the integration time is 10s.

[0016] Further, the foodborne pathogenic bacteria is Escherichia coli (E.coli) Migula.

[0017] The black phosphorus / molybdenum disulfide nanoflower composite material prepared by the method is used for preparing an antibacterial agent.

[0018] Compared with the prior art, the method for preparing the black phosphorus / molybdenum disulfide nanoflower composite material and the application thereof in detecting foodborne pathogenic bacteria has the advantages that the method mainly uses a hierarchical centrifugation assisted liquid phase exfoliation method, a hydrothermal method and the like, black phosphorus can effectively promote molybdenum disulfide to stack into a flower shape, so that the molybdenum disulfide has a completely exposed active surface, due to the charge transfer process induced by high electron density, the black phosphorus / molybdenum disulfide nanoflower composite substrate can not only enhance SE SR, but also exhibit extremely high photocatalytic activity and photothermal performance. Since the black phosphorus / molybdenum disulfide composite material has a three-dimensional channel microstructure rough surface, it is beneficial to the enrichment of to-be-detected Raman molecules, and the Raman enhancement effect can be further improved.

[0019] In summary, the method for preparing the black phosphorus / molybdenum disulfide nanoflower composite material and the application thereof in detecting foodborne pathogenic bacteria. The method is synthesized by a chemical method rather than physical mixing, so that the molybdenum disulfide is effectively stacked into a flower on the black phosphorus nanosheet, the large surface area is full of active electrons and functional groups, which is beneficial to molecular enrichment, and the composite material has a wide absorption spectrum band from ultraviolet to near infrared, which is more conducive to light capture, has strong photo-thermal conversion and chemical enhanced Raman signal effect, and double effects are used to obtain more sensitive detection results, reduce the Raman detection limit, and realize SERS detection, photothermal and photocatalytic synergistic sterilization. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 This is a scanning electron microscope photograph of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 1 of the present invention;

[0021] Figure 2 This is a scanning electron microscope photograph of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention;

[0022] Figure 3 This is a scanning electron microscope photograph of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 3 of the present invention;

[0023] Figure 4 This is a scanning electron microscope photograph of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 4 of the present invention; Figure 5 UV-vis spectra of black phosphorus, molybdenum disulfide, and black phosphorus / molybdenum disulfide nanoflower composite materials prepared in Examples 1, 2, 3, and 4 of the present invention;

[0024] Figure 6 The SERS spectrum of foodborne pathogens detected using the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 1 of the present invention;

[0025] Figure 7 The SERS spectra of foodborne pathogens detected using the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention and black phosphorus, molybdenum disulfide nanoflowers, and a blank control group;

[0026] Figure 8 The SERS spectrum of foodborne pathogens detected using the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 3 of the present invention;

[0027] Figure 9 The SERS spectrum of foodborne pathogens detected using the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 4 of the present invention;

[0028] Figure 10 The SERS spectra of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention detecting foodborne pathogens at different concentrations;

[0029] Figure 11 The black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention is 1507cm -1 The linear relationship between the peak intensity of the SERS signal and the concentration of E. coli Migula;

[0030] Figure 12The black phosphorus / molybdenum disulfide nanoflower composite prepared in Example 2 of the present invention and the black phosphorus nanosheets and molybdenum disulfide nanoflower materials were heated at 808nm (2W / cm 2 ) Temperature change of the solution under laser irradiation;

[0031] Figure 13 808nm (2W / cm 2 ) Under laser irradiation, the optical density of E. coli Migula at 600nm after incubation with the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention, as well as black phosphorus nanosheets, molybdenum disulfide nanoflowers and the like. DETAILED DESCRIPTION

[0032] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. Specific embodiment 1

[0034] Example 1

[0035] A method for preparing a black phosphorus / molybdenum disulfide nanoflower composite material comprises the following steps:

[0036] 1. Preparation of black phosphorus nanosheets using fractional centrifugation-assisted liquid phase exfoliation

[0037] Black phosphorus was added to deionized water to prepare a 1 mg / ml black phosphorus solution, and then the dissolved oxygen in the liquid was removed by argon bubbling, and after ultrasonic treatment with a cell ultrasonic crusher at 5°C for 4 hours, a dark brown precipitate was collected by centrifugation at 3000 rpm for 15 minutes, and after removing the light brown liquid, the dark brown precipitate obtained by centrifugation was washed with deionized water and ethanol several times (12000 rpm for 15 minutes), and vacuum dried at 60°C for 12 hours to obtain black phosphorus nanosheet particles; 2. The black phosphorus / molybdenum disulfide nanoflower composite material was prepared by a hydrothermal method. The black phosphorus nanosheets prepared in step 1 were added to The mixture was added into 10 ml of deionized water and ultrasonicated for ten minutes to obtain a black phosphorus nanosheet aqueous solution with a concentration of 1.8 mg / ml; at the same time, 5 ml of an ammonium molybdate aqueous solution with a concentration of 1.4 mg / ml, 5 ml of a 3.04 mg / ml thiourea aqueous solution and the above-mentioned black phosphorus nanosheet aqueous solution were transferred to a polytetrafluoroethylene-lined stainless steel autoclave and ultrasonicated for 10 minutes, and heated to 200°C. After keeping for 24 hours, centrifugation was performed, and the black precipitate obtained by centrifugation was washed several times with deionized water and ethanol, and dried in vacuum at 60°C for 12 hours to obtain a black phosphorus / molybdenum disulfide nanoflower composite material.

[0038] Figure 1 The scanning electron microscope photo of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in this embodiment is shown. Figure 1It can be seen that the surface of the prepared black phosphorus / molybdenum disulfide nanoflowers has a groove-like structure, consisting of many three-dimensional grooves and protruding patterns, and the molybdenum disulfide nanoflowers are evenly attached to the surface of the black phosphorus nanosheets.

[0039] Example 2

[0040] A method for preparing a black phosphorus / molybdenum disulfide nanoflower composite material comprises the following steps:

[0041] 1. Preparation of black phosphorus nanosheets using fractional centrifugation-assisted liquid phase exfoliation

[0042] Black phosphorus was added to deionized water to prepare a 1 mg / mL black phosphorus solution. Dissolved oxygen in the liquid was then removed by bubbling argon gas, and the solution was sonicated at 5°C for 4 hours using a cell ultrasonic disruptor. The dark brown precipitate was then collected by centrifugation at 3000 rpm for 15 minutes. After removing the light brown liquid, the dark brown precipitate obtained by centrifugation was washed several times with deionized water and ethanol (12000 rpm for 15 minutes). After vacuum drying at 60°C for 12 hours, black phosphorus nanosheet particles were obtained.

[0043] 2. Preparation of black phosphorus / molybdenum disulfide nanoflower composites by hydrothermal method

[0044] The black phosphorus nanosheets prepared in step 1 were added to 10 ml of deionized water and ultrasonicated for ten minutes to obtain a 2 mg / ml aqueous solution of black phosphorus nanosheets. At the same time, 5 ml of a 2 mg / ml aqueous solution of ammonium molybdate, 5 ml of a 4.34 mg / ml aqueous solution of thiourea, and the above-mentioned aqueous solution of black phosphorus nanosheets were transferred to a polytetrafluoroethylene-lined stainless steel autoclave and ultrasonicated for 10 minutes. The mixture was heated to 200°C and kept for 24 hours, and then centrifuged. The black precipitate obtained by centrifugation was washed several times with deionized water and ethanol, and dried in vacuum at 60°C for 12 hours to obtain a black phosphorus / molybdenum disulfide nanoflower composite material.

[0045] Figure 2 The scanning electron microscope photo of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in this embodiment is shown. Figure 2 It can be seen that the surface of the prepared black phosphorus / molybdenum disulfide nanoflowers has a groove-like structure, consisting of many three-dimensional grooves and protruding patterns, and the molybdenum disulfide nanoflowers are evenly attached to the surface of the black phosphorus nanosheets.

[0046] Example 3

[0047] A method for preparing a black phosphorus / molybdenum disulfide nanoflower composite material comprises the following steps:

[0048] 1. Preparation of black phosphorus nanosheets using fractional centrifugation-assisted liquid phase exfoliation

[0049] The black phosphorus is added to the deionized water to prepare a 1 mg / ml black phosphorus solution, then the dissolved oxygen in the liquid is removed by argon bubbling, and after ultrasonic treatment at 5°C for 4 hours, the dark brown precipitate is collected by centrifugation at 3000 rpm for 15 minutes, after removing the light brown liquid, the dark brown precipitate obtained by centrifugation is washed with deionized water and ethanol (12000 rpm, 15 minutes) several times, and after vacuum drying at 60°C for 12 hours, black phosphorus nanosheet particles are obtained; 2, black phosphorus / molybdenum disulfide nanoflower composite material is prepared by hydrothermal method

[0050] The black phosphorus nanosheet prepared in step 1 is added to 10 ml of deionized water, and ultrasonic treatment is performed for 10 minutes to obtain a black phosphorus nanosheet aqueous solution with a concentration of 2 mg / ml; at the same time, 5 ml of an ammonium molybdate aqueous solution with a concentration of 4 mg / ml, 5 ml of an 8.68 mg / ml thiourea aqueous solution, and the above black phosphorus nanosheet aqueous solution are transferred into a polytetrafluoroethylene-lined stainless steel autoclave and ultrasonic treatment is performed for 10 minutes, and then heated to 200°C and kept for 24 hours, then centrifuged, and the black precipitate obtained by centrifugation is washed with deionized water and ethanol several times, and vacuum dried at 60°C for 12 hours to obtain a black phosphorus / molybdenum disulfide nanoflower composite material.

[0051] Figure 3 The scanning electron microscope image of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in this embodiment is shown. Figure 3 As can be seen from the above, the prepared black phosphorus / molybdenum disulfide nanoflower has a gully-shaped structure on the surface, and is composed of many three-dimensional channels and protruding patterns, and the molybdenum disulfide nanoflowers are uniformly attached to the surface of the black phosphorus nanosheet.

[0052] Example 4

[0053] A method for preparing a black phosphorus / molybdenum disulfide nanoflower composite material, comprising the following steps:

[0054] 1. Preparing black phosphorus nanosheets by hierarchical centrifugation assisted liquid phase exfoliation

[0055] Black phosphorus was added to deionized water to prepare a 1 mg / ml black phosphorus solution, and then the dissolved oxygen in the liquid was removed by argon bubbling, and after ultrasonic treatment with a cell ultrasonic crusher at 5°C for 4 hours, a dark brown precipitate was collected by centrifugation at 3000 rpm for 15 minutes, and after removing the light brown liquid, the dark brown precipitate obtained by centrifugation was washed with deionized water and ethanol several times (12000 rpm for 15 minutes), and vacuum dried at 60°C for 12 hours to obtain black phosphorus nanosheet particles; 2. The black phosphorus / molybdenum disulfide nanoflower composite material was prepared by a hydrothermal method. The black phosphorus nanosheets prepared in step 1 were added to The mixture was added into 10 ml of deionized water and ultrasonicated for ten minutes to obtain a 2.2 mg / ml aqueous solution of black phosphorus nanosheets. At the same time, 5 ml of a 6 mg / ml aqueous solution of ammonium molybdate, 5 ml of a 13.03 mg / ml aqueous solution of thiourea and the above-mentioned aqueous solution of black phosphorus nanosheets were transferred to a polytetrafluoroethylene-lined stainless steel autoclave and ultrasonicated for 10 minutes. The mixture was heated to 200°C and kept for 24 hours before centrifugation. The black precipitate obtained by centrifugation was washed several times with deionized water and ethanol, and dried in vacuum at 60°C for 12 hours to obtain a black phosphorus / molybdenum disulfide nanoflower composite material.

[0056] Figure 4 The scanning electron microscope image of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in this embodiment is shown. Figure 4 It can be seen that the surface of the prepared black phosphorus / molybdenum disulfide nanoflowers has a groove-like structure, consisting of many three-dimensional grooves and protruding patterns, and the molybdenum disulfide nanoflowers are evenly attached to the surface of the black phosphorus nanosheets.

[0057] Figure 5 The UV-vis spectra of the black phosphorus / molybdenum disulfide nanoflower composite materials prepared in Examples 1, 2, 3, and 4 of the invention are shown in FIG. Figure 9 As can be seen in the image, the absorption peak of the black phosphorus / MoS2 nanoflower composite approaches the combined absorption peaks of individual black phosphorus nanosheets and MoS2 nanoflowers, indicating a successful composite of black phosphorus and MoS2. Multiple absorption peaks interconnect to form a broad absorption band, which helps absorb more light energy, thereby improving the material's charge transfer efficiency and photocatalytic ability. Specific embodiment 2

[0059] Detection and application of foodborne pathogens

[0060] 5 mg of the black phosphorus / molybdenum disulfide nanoflower composite prepared in Example 1 was added to 500 μL of a foodborne pathogenic bacteria E. coli Migula solution, and after oscillation, the solution was incubated at 250 rpm for 4.5 hours using a rotary oscillator, and then the black phosphorus / molybdenum disulfide nanoflower solution with the adhered bacteria was washed twice with deionized water. The collected precipitate was dispersed in 500 μL of deionized water, and 10 μL of the mixed liquid was dropped on a 0.5 x 0.5 silicon wafer, which was dried at 60°C, and then the spectrum was measured using a Raman spectrometer. The Raman spectrometer used a 532 nm semiconductor laser as an excitation source, the laser spot diameter was 12.5 μm, the numerical aperture was 0.55, the laser power was set to 1 mw, and the integration time was 10 s. The foodborne pathogenic bacteria solution was prepared as follows: 5 mL of a lysogenic broth (LB) was autoclaved (121°C, 15 minutes) and then left to stand at room temperature, and 10 μL of the thawed bacterial solution was taken with an inoculation loop and added to the LB medium, which was then incubated at 120 rpm and 37°C for 6 hours in a rotary oscillator to obtain a bacterial stock solution. The bacterial stock solution was centrifuged at 4000 rpm for 10 minutes for 3 times, and the precipitate was collected and dispersed in 5 mL of deionized water to obtain the foodborne pathogenic bacteria solution. At the same time, 50 μL of the bacterial stock solution was added to 450 μL of the LB broth, and after oscillation, 50 μL was transferred to the LB agar, which was then placed in an oven at 37°C for 24 hours, and the colonies were counted. The concentration of the foodborne pathogenic bacteria E. coli Migula used for detection was 6.2 x 10 6 CFU / ML.

[0061] Figure 6 For the SERS spectrum of the foodborne pathogenic bacteria solution detected using the black phosphorus / molybdenum disulfide nanoflower composite prepared in Example 1, it can be seen from FIG. 1 that the intensity of E. coli Migula at 1507 wave numbers was 4308.2. Figure 6

[0062] Figure 7 For the SERS spectrum of the foodborne pathogenic bacteria solution detected using the black phosphorus / molybdenum disulfide nanoflower composite prepared in Example 2, it can be seen from FIG. 2 that the intensity of E. coli Migula at 1507 wave numbers was 6671.6. Figure 7

[0063] Figure 8 For the SERS spectrum of the foodborne pathogenic bacteria solution detected using the black phosphorus / molybdenum disulfide nanoflower composite prepared in Example 3, it can be seen from FIG. 3 that the intensity of E. coli Migula at 1507 wave numbers was 5790. Figure 8

[0064] ​​​Figure 9 The SERS spectrum of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 4 was used to detect the bacterial liquid of foodborne pathogens. Figure 9 It can be seen that the intensity of E. coli Migula at 1507 wavenumbers is 4928.8.

[0065] From the above experimental results, it can be seen that the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 has the strongest SERS signal for detecting foodborne pathogens. The black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 is further used for further experimental analysis.

[0066] The black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 was used to detect the SERS spectra of foodborne pathogens, black phosphorus nanosheets, molybdenum disulfide nanoflowers, and a blank control group. Foodborne pathogens were incubated with black phosphorus, molybdenum disulfide nanoflowers, and a black phosphorus / molybdenum disulfide nanoflower composite material (the method was the same as above). The concentration of foodborne pathogens was 6.2×10 6 CFU / ML. Detected using a 532 nm Raman spectrometer.

[0067] from Figure 7 As can be seen, the intensities of E. coli Migula at 1507 wavenumber are 308.8, 286.4, and 6671.6 when the substrates are black phosphorus nanosheets, molybdenum disulfide nanoflowers, and the black phosphorus / molybdenum disulfide nanoflower composite, respectively. When no nanomaterials are added, the intensity at this wavenumber is 82.4. Compared to either black phosphorus nanosheets or molybdenum disulfide nanoflowers alone, the black phosphorus / molybdenum disulfide nanoflower composite exhibits superior SERS intensity. This is due to the composite's unique three-dimensional groove structure, which facilitates molecular enrichment, and the more closely matched band gaps between black phosphorus and molybdenum disulfide, resulting in a synergistic enhancement effect. The preparation method for the black phosphorus nanosheets is the same as in Example 1 above; the preparation method for the molybdenum disulfide nanoflowers is as follows: 30 mg of ammonium molybdate and 25.14 mg of thiourea are mixed in 15 mL of deionized water with vigorous stirring. After the reagents are fully dissolved, the mixture is added to a hydrothermal autoclave, which is sealed and maintained at 200°C for 24 hours. After cooling, the mixture was washed with anhydrous ethanol and deionized water. Finally, the purified product was dried under vacuum at 60°C for 6 hours to obtain molybdenum disulfide nanoflowers. Specific embodiment three

[0069] Sensitivity analysis

[0070] Figure 10 The SERS spectrum of the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention for detecting foodborne pathogens, and the 1507 cm -1The corresponding dose-response curve of the peak intensity at , the pathogen concentration ranged from 6.2×10 2 to 6.2×10 6 CFU / ML changes. Figure 10 It can be seen that as the concentration of E. coli Migula increases, the SERS signal intensity gradually increases.

[0071] Depend on Figure 11 It can be seen that at 6.2×10 2 to 6.2×10 6 In the CFU / ML range, the SERS signal intensity showed a good linear relationship with the logarithm of the E. coli Migula concentration, and the linear regression equation was y = 1479.77241x - 3827.62395, R 2 =0.994. Based on the threefold signal-to-noise ratio, the detection limit was estimated to be 568 CFU / mL. This indicates that the black phosphorus / molybdenum disulfide nanoflower composite material can achieve extremely high SERS sensitivity for detection. Specific embodiment 4

[0073] Photothermal sterilization performance analysis

[0074] In order to evaluate the photothermal performance of the materials, black phosphorus nanosheets, molybdenum disulfide nanoflowers, and black phosphorus / molybdenum disulfide nanoflower solutions were added to a 1.3 mL quartz cell, and then irradiated with an 808 nm laser at 2.0 W cm -2 The power density was irradiated for 10 min, and the temperature changes were monitored and recorded using an infrared thermal imaging system. Figure 12 The black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention and the black phosphorus nanosheets and molybdenum disulfide nanoflowers were heated at 808 nm (2 W / cm 2 ) Temperature change of the solution under laser irradiation for 10 minutes.

[0075] The results are Figure 12 It can be seen that under the irradiation of laser, black phosphorus, molybdenum disulfide and black phosphorus / molybdenum disulfide nanoflower composite materials heated up to 44.3°, 51.2° and 58.7° respectively and remained stable. Compared with black phosphorus or molybdenum disulfide alone, the black phosphorus / molybdenum disulfide nanocomposite material heated up faster and had a higher saturation temperature, indicating that the black phosphorus / molybdenum disulfide nanoflower composite material has super strong photothermal conversion ability and is expected to be used for photothermal sterilization.

[0076] In order to evaluate the photothermal and photocatalytic synergistic antibacterial performance of the materials, black phosphorus, molybdenum disulfide, or black phosphorus / molybdenum disulfide were added to LB medium with cultured bacteria, and then an 808 nm laser was used at 2.0 W cm -2After irradiation for 0-18 minutes, the bacterial suspensions were shaken at 37°C for another 24 hours, and their optical density (OD) at 600 nm was measured on a UV spectrophotometer. Figure 13 808nm (2W / cm 2 ) Under laser irradiation, the optical density of E. coli Migula at 600nm after incubation with the black phosphorus / molybdenum disulfide nanoflower composite material prepared in Example 2 of the present invention, as well as black phosphorus nanosheets and molybdenum disulfide nanoflowers.

[0077] The results are Figure 13 It can be seen that with the increase of laser irradiation time, the optical density of E. coli Migula at 600nm decreased significantly, indicating that the survival rate of E. coli Migula was gradually decreasing. Among them, the black phosphorus / molybdenum disulfide nanoflower composite material effectively killed bacteria within 12 minutes. The bactericidal effect of the composite material was significantly higher than that of the single material. The reason is that when the sample is exposed to light with appropriate photon energy, a large number of electrons (e - ) can be excited to the conduction band and leave holes in the valence band (h + These electrons can automatically migrate to the valence band of MoS2, effectively avoiding the recombination of photogenerated electron-hole pairs and improving the photocatalytic efficiency. The highly active electrons will be captured by the oxygen adsorbed on the surface of the nanocomposite material and produce superoxide radicals (·O2 - At the same time, the interaction between the corresponding holes and the surface H2O will produce hydroxyl groups (·OH - ), O2 - and OH - The group has strong oxidizing ability and can directly oxidize E. coli Migula.

[0078] The above description is not intended to limit the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by persons of ordinary skill in the art within the spirit and scope of the present invention shall also fall within the scope of protection of the present invention.

Claims

1. A method for detecting foodborne pathogens based on black phosphorus / molybdenum disulfide nanoflower composite materials, which is not intended for diagnosis or treatment, is characterized by The preparation method of the black phosphorus / molybdenum disulfide nanoflower composite material comprises the following steps: (1) Preparation of black phosphorus nanosheets using fractionated centrifugal assisted liquid phase exfoliation Black phosphorus was added to deionized water to prepare a 1 mg / ml black phosphorus solution, and then dissolved oxygen in the liquid was removed by bubbling argon gas. After sonication at 5°C for 4 hours using a cell ultrasonic crusher, a dark brown precipitate was collected after centrifugation at 3000 rpm for 15 minutes. After removing the light brown liquid, the collected dark brown precipitate was washed 2-4 times with deionized water and ethanol, and dried in vacuo at 60°C for 12 hours to obtain black phosphorus nanosheets. (2) Preparation of black phosphorus / molybdenum disulfide nanoflower composites by hydrothermal method The black phosphorus nanosheets prepared in step (1) are added to deionized water, and ultrasonicated for 8 to 12 minutes to obtain a black phosphorus nanosheet aqueous solution; the black phosphorus nanosheet aqueous solution, ammonium molybdate aqueous solution and thiourea aqueous solution are mixed in a volume ratio of 2:1:1, placed in a polytetrafluoroethylene-lined stainless steel autoclave for ultrasonication for 10 minutes, and heated to 200°C. After holding for 24 hours, centrifugation is performed, and the black precipitate obtained by centrifugation is washed with deionized water and ethanol for 2-4 times, and vacuum-dried at 60°C for 12 hours to obtain a black phosphorus / molybdenum disulfide nanoflower composite material. The black phosphorus nanosheets aqueous solution has a concentration of 1.8-2.2 mg / ml, the ammonium molybdate aqueous solution has a concentration of 1.4-6 mg / ml, and the thiourea aqueous solution has a concentration of 3.04-13.03 mg / ml. The method for detecting foodborne pathogens based on the black phosphorus / molybdenum disulfide nanoflower composite material comprises the following steps: adding the black phosphorus / molybdenum disulfide nanoflower composite material to a solution containing foodborne pathogens at a mass volume ratio of 1 mg:100 μl, shaking, and rotating the mixture at 250°C. After incubation at rpm for 4.5 hours, the black phosphorus / molybdenum disulfide nanoflower solution with attached foodborne pathogens was washed twice with deionized water, the collected precipitate was dispersed in 500 μL of deionized water, 10 μL of the mixed liquid was dropped on a 0.5×0.5 silicon wafer, and after drying at 60°C, spectral measurement was performed using a Raman spectrometer to detect the Raman signal. Based on the linear relationship between foodborne pathogens and Raman intensity, the concentration of foodborne pathogens in the test solution was calculated.

2. The method for detecting foodborne pathogens based on a black phosphorus / molybdenum disulfide nanoflower composite material according to claim 1, wherein the method is not intended for diagnosis or treatment and is characterized in that: The Raman spectrometer uses a 532nm semiconductor laser as an excitation source, with a laser spot diameter of 12.5μm, a numerical aperture of 0.55, a laser power of 1mw, and an integration time of 10s.

3. The method for detecting foodborne pathogens based on a black phosphorus / molybdenum disulfide nanoflower composite material according to claim 1, wherein the method is not intended for diagnosis or treatment, and is characterized in that: The foodborne pathogenic bacteria is Escherichia coli E. coli Migula.

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