An In2S3 / MoS2@Fe-CNTs photoactive material, a self-powered aptamer sensor and its application

Abstract

This invention relates to an In2S3 / MoS2@Fe-CNTs photoactive material, a self-powered aptamer sensor, and their applications, belonging to the field of biosensor technology. The In2S3 / MoS2@Fe-CNTs heterojunction photoactive material comprises a Fe-doped CNTs matrix and In2S3 / MoS2 hybrid nanosheets attached to a Fe-doped carbon nanotube matrix. The In2S3 / MoS2@Fe-CNTs heterojunction photoactive material of this invention belongs to a one-dimensional / two-dimensional heterostructure, which enhances light absorption characteristics, promotes the separation and transfer of photogenerated electrons and holes, and has a large specific surface area with abundant aptamer anchoring sites.

Description

Technical Field

[0001] This invention relates to an In2S3 / MoS2@Fe-CNTs photoactive material, a self-powered aptamer sensor, and their applications, belonging to the field of biosensor technology. Background Technology

[0002] Staphylococcus aureus is a representative Gram-positive bacterium and the most common pathogen causing purulent infections in humans, as well as a common foodborne pathogen. Staphylococcus aureus commonly resides on the skin, nasal cavity, throat, gastrointestinal tract, inflamed and purulent ulcers in humans and animals, and in the environment, including air and sewage. Therefore, ingestion of Staphylococcus aureus can easily cause purulent inflammation, toxic shock syndrome, scalded skin syndrome, and even death. Against this backdrop, achieving sensitive and accurate detection of Staphylococcus aureus is crucial for protecting health and ensuring environmental monitoring.

[0003] Currently, commonly used methods for detecting Staphylococcus aureus include traditional culture, instrumental detection, and molecular biological detection. Traditional detection of Staphylococcus aureus relies on bacterial culture, which provides reliable and stable results, but typically takes 2–3 days to obtain results. Instrumental detection, such as HPLC, mass spectrometry, and polymerase chain reaction (PCR), can produce results in just 1–5 hours, offering rapid and sensitive results. However, these devices are usually expensive and require professional operation. Molecular biological detection can provide rapid results, but it is prone to false positives and has poor detection stability.

[0004] Biosensors, as a novel detection method, offer advantages such as convenience, time-saving, high precision, simple equipment, low cost, and ease of miniaturization. Data collection and processing are also straightforward and pollution-free, enabling high-throughput on-site sample detection. Integrating electrochemical methods with aptamer biosensors offers fast response, low cost, high efficiency, and simple operation, and has been widely used for the sensitive and selective detection of Staphylococcus aureus. Furthermore, existing technologies have begun to research photoelectrochemical aptamer sensors based on semiconductor nanomaterials for Staphylococcus aureus detection. However, due to the small specific surface area, low functionality, and simple nanostructure of most semiconductor materials, the adsorption / anchoring sites for biological probe molecules and target substrates are limited, thus reducing the transport quality and the sensitivity and accuracy of detection during the catalytic reaction process. Summary of the Invention

[0005] The purpose of this invention is to provide an In2S3 / MoS2@Fe-CNTs heterojunction photoactive material that solves the problems of small specific surface area, low functionality, and limited adsorption / anchoring points of aptamers in the prior art.

[0006] The second objective of this invention is to provide a method for preparing In2S3 / MoS2@Fe-CNTs heterojunction photoactive materials, which solves the problems of small specific surface area, low functionality, and limited adsorption / anchoring sites of aptamers in the prior art.

[0007] The third objective of this invention is to provide a self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction, which has the advantages of high selectivity, good reproducibility, good stability and good regenerability.

[0008] The fourth objective of this invention is to provide an application of a self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction in the detection of foodborne bacteria, thereby solving the problems of low sensitivity and low accuracy in the detection of Staphylococcus aureus in the prior art.

[0009] To achieve the above objectives, the technical solution adopted by the In2S3 / MoS2@Fe-CNTs heterojunction photoactive material of the present invention is as follows:

[0010] An In2S3 / MoS2@Fe-CNTs heterojunction photoactive material comprises an Fe-doped carbon nanotube matrix and In2S3 / MoS2 hybrid nanosheets attached to the Fe-doped carbon nanotube matrix.

[0011] The In2S3 / MoS2@Fe-CNTs heterojunction photoactive material of the present invention belongs to a one-dimensional / two-dimensional heterostructure, which enhances the light absorption characteristics, promotes the transfer and separation of photogenerated electrons and holes, and has a large specific surface area and abundant aptamer anchoring sites.

[0012] Preferably, the Fe-doped carbon nanotube matrix is ​​an n-type semiconductor, and the In2S3 / MoS2 hybrid nanosheet is a p-type semiconductor, forming a pn junction. The In2S3 / MoS2@Fe-CNTs pn heterojunction of this invention enhances the directional charge transfer of photogenerated electron-hole pairs and strengthens charge separation.

[0013] The technical solution adopted in the preparation method of the In2S3 / MoS2@Fe-CNTs heterojunction photoactive material of the present invention is as follows:

[0014] A method for preparing In2S3 / MoS2@Fe-CNTs heterojunction photoactive materials includes the following steps: in-situ generation of In2S3 / MoS2 hybrid nanosheets on Fe-doped carbon nanotubes to obtain In2S3 / MoS2@Fe-CNTs.

[0015] This invention utilizes In2S3 / MoS2 hybrid two-dimensional semiconductor nanosheets to prepare one-dimensional / two-dimensional heterostructures by in-situ growth around one-dimensional Fe-doped carbon nanotubes. These heterostructures enable rapid, long-distance electron transfer, enhance light absorption characteristics, and promote the transfer and separation of photogenerated electrons and holes. Furthermore, the photoactive material exhibits a large specific surface area and abundant aptamer anchoring sites. This method is simple to operate and suitable for industrial production.

[0016] The specific process for synthesizing In2S3 / MoS2@Fe-CNTs preferably involves a solvothermal reaction of indium salt, phosphomolybdic acid, sulfide, and Fe-doped carbon nanotubes in a solvent.

[0017] To better synthesize In2S3 / MoS2@Fe-CNTs, more preferably, the indium salt is InCl3 and the sulfide is thioacetamide.

[0018] Preferably, when indium salt, phosphomolybdic acid, sulfide and Fe-doped carbon nanotubes are mixed in a solvent, an aqueous solution of indium salt, phosphomolybdic acid and Fe-doped carbon nanotubes is mixed with an ethanol solution of sulfide.

[0019] More preferably, the aqueous solution contains 37-40% indium salt, 37-40% phosphomolybdic acid, and 7-8% Fe-doped carbon nanotubes.

[0020] More preferably, the drying temperature is 50–80°C, and the drying time is 10–16 hours.

[0021] To ensure a complete reaction in the system, preferably, the amount of indium salt added is 4 to 6 times the mass of Fe-doped CNTs, the amount of phosphomolybdic acid added is 4 to 6 times the mass of Fe-doped CNTs, and the amount of sulfide added is 8 to 12 times the mass of Fe-doped CNTs.

[0022] To improve the efficiency of the synthesis, preferably, the temperature of the thermal reaction is 190–210°C and the reaction time is 10–16 h.

[0023] The technical solution adopted by the self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction of the present invention is as follows:

[0024] A self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction includes a photocathode based on the aforementioned In2S3 / MoS2@Fe-CNTs heterojunction photoactive material and a photoanode based on Fe-CNTs; the photocathode includes an electrode substrate, an In2S3 / MoS2@Fe-CNTs material composited on the electrode substrate, and an aptamer targeting foodborne bacteria bound to the In2S3 / MoS2@Fe-CNTs material.

[0025] This invention relates to a self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction. This aptamer sensor is constructed based on the synergistic effect of dual photoelectrodes. The In2S3 / MoS2@Fe-CNTs heterojunction photoactive material serves as the photocathode, and Fe-CNTs serve as the photoanode. The In2S3 / MoS2@Fe-CNTs pn heterojunction enhances charge separation and directional charge transfer of photogenerated electron-hole pairs. When combined with the Fe-CNTs photoanode, it yields amplified photoelectrochemical signals and high power density. To specifically identify foodborne bacteria, foodborne bacteria aptamers are immobilized on the photoelectrode.

[0026] In addition, this self-powered adapter sensor has good reproducibility, stability and regenerability, and high selectivity.

[0027] Preferably, the foodborne bacteria is Staphylococcus aureus.

[0028] The sequence of the Staphylococcus aureus targeting aptamer is as follows: 5'-GCA ATG GTA CGG TAC TTC CTCGGC ACG TTC TCA GTA GCG CTC GCT GGT CAT CCC ACA GCT ACG TCA AAA GTG CAC GCTACT TTG CTA A-3'.

[0029] Preferably, the photoanode includes an electrode substrate and a Fe-CNTs material composited on the electrode substrate.

[0030] More preferably, the electrode substrate is an ITO glass substrate.

[0031] To eliminate non-specific absorption, BSA is preferably incorporated into the photocathode.

[0032] The technical solution adopted in the application of the self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction in the detection of foodborne bacteria is as follows:

[0033] An application of a self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction in the detection of foodborne bacteria: The self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction described above is used to detect foodborne bacteria in the sample to be tested.

[0034] More preferably, the foodborne bacteria is Staphylococcus aureus.

[0035] The self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction of the present invention detects Staphylococcus aureus in the test sample by specifically recognizing and capturing Staphylococcus aureus using a Staphylococcus aureus aptamer. The self-powered aptamer sensor has been measured to have a performance of 10 to 1 × 10⁻⁶. 7 CFU mL -1 The limit of detection for Staphylococcus aureus over a wide linear range is 1.2 CFU / mL. -1 The recovery rate reached over 93.33%, and the RSDs were within the range of 0.77 to 4.36%. Attached Figure Description

[0036] Figure 1 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of In2S3 / MoS2 in Example 1; wherein, Figure 1 a and 1b are its low-magnification and high-magnification SEM images, respectively. Figure 1 c, 1d, and 1e are its low-magnification, high-magnification, and high-resolution TEM images, respectively. Figure 1 f is the EDX elemental mapping image corresponding to In2S3 / MoS2: In (cyan), O (red), Mo (purple), S (blue), P (green), N (brown) and C (yellow);

[0037] Figure 2 These are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of Fe-CNTs from Example 1; wherein, Figure 2 a and 2b are its low-magnification and high-magnification SEM images, respectively. Figure 2 c, 2d, and 2e are its low-magnification, high-magnification, and high-resolution TEM images, respectively. Figure 2 f is the EDX elemental mapping image corresponding to Fe-CNTs: iron (lavender), C (yellow), N (brown), and O (red);

[0038] Figure 3 The images shown are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of In2S3 / MoS2@Fe-CNTs in Example 1; wherein, Figure 3 a and 3b are its low-magnification and high-magnification SEM images, respectively. Figure 3 c, 3d, and 3e are its low-magnification, high-magnification, and high-resolution TEM images, respectively. Figure 3 f is the EDX elemental mapping image corresponding to In2S3 / MoS2@Fe-CNTs: Fe (lavender), In (cyan), O (red), Mo (purple), N (brown), P (green), S (blue) and C (yellow);

[0039] Figure 4 The image shown is the EDX spectrum from Example 1, where... Figure 4 a, 4b, and 4c are EDX spectra of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs, respectively;

[0040] Figure 5 The XRD and Raman spectra of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs in Example 1 are shown below. Figure 5 a is the XRD pattern. Figure 5 b is the Raman spectrum;

[0041] Figure 6 The figures show the N2 adsorption-desorption isotherms and pore size distribution curves of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs in Example 1. Figure 6 a represents the N2 adsorption-desorption isotherm. Figure 6 b represents the aperture distribution curve;

[0042] Figure 7 The image shows the XPS spectrum, where... Figure 7 a represents the XPS measurement scan spectra of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs in Example 1. Figure 7 bf are high-resolution In 3d, Mo 3d, S2p, C 1s and O1s XPS spectra of In2S3 / MoS2@Fe-CNTs, respectively.

[0043] Figure 8 ad represents the XPS EPR spectrum, UV-Vis diffuse reflectance spectrum, and (αhν) spectrum of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs in Example 1, respectively. 2 Relationship diagram with hν, EIS Nyquist diagram;

[0044] Figure 9 The graph shows the Mott-Schottky curve, where... Figure 9 a is the Mott-Schottky curve of In2S3 / MoS2 in Example 1. Figure 9 b is the Mott-Schottky curve of Fe-CNTs in Example 1;

[0045] Figure 10 The graph shows the photocurrent response, where... Figure 10 a is the photocurrent response diagram of the Fe-CNTs photoanode. Figure 10 b shows the photocurrent response in In2S3 / MoS2 and In2S3 / MoS2@Fe-CNTs photocathodes. Figure 10 c shows the photocurrent response of In2S3 / MoS2 and In2S3 / MoS2@Fe-CNTs in the dual photoelectrode system;

[0046] Figure 11 The graphs show the VI, PI, and OCP-time curves, where... Figure 11 The figures ac represent the VI, PI, and OCP curves of PFCs assembled using Fe-CNTs / ITO photoanodes and different photocathodes, respectively. Figure 11 df are VI, PI and OCP-time curves of PFC constructed using Fe-CNTs / ITO photoanode and In2S3 / MoS2@Fe-CNTs / ITO photocathode during the aptamer sensor construction and target detection process, respectively.

[0047] Figure 12 This is a graph showing the influence of different factors on the OCP value of PFC. Figure 12 The figures a and b represent the effects of In2S3 / MoS2@FeCNTs dosage, aptamer concentration, aptamer incubation time, and Staphylococcus aureus binding time on the OCP value of PFC.

[0048] Figure 13 a and b represent the detection of different concentrations (10, 1×10) by a self-powered PFC system, respectively. 2 , 1×10 3 , 1×10 4 , 1×10 5 , 1×10 6 , 1×10 7 CFU·mL -1 VI and PI curves of Staphylococcus aureus Figure 13 c represents the dependence of ΔPmax on the concentration of Staphylococcus aureus (illustration: calibration curve corresponding to ΔPmax and Staphylococcus aureus concentration); Figure 13 d is the OCP curve of different concentrations of Staphylococcus aureus detected by the self-powered PFC system. Figure 13 e is ΔE ocp Dependence on Staphylococcus aureus concentration (Illustration: ΔE) ocp (Calibration curve corresponding to the concentration of Staphylococcus aureus);

[0049] Figure 14The graph shows the performance of the PFC aptamer sensor. Figure 14 The graphs a and b represent the selectivity, reproducibility, stability, and reproducibility of the PFC aptamer sensor, respectively, and the error bars represent the average standard error of three measurements (n=3). Detailed Implementation

[0050] The self-powered aptamer sensor based on the In2S3 / MoS2@Fe-CNTs heterojunction of the present invention includes a photocathode based on the above-mentioned In2S3 / MoS2@Fe-CNTs heterojunction photoactive material and a photoanode based on Fe-CNTs.

[0051] The Fe-doped carbon nanotubes of the present invention are obtained by first reacting melamine and cyanuric acid to generate melamine cyanurate (MCA), then mixing melamine cyanurate and glucose to obtain MCA / glucose precursor (MCA / G), and finally mixing MCA / G with iron salt, freezing, and calcining under a protective atmosphere.

[0052] Furthermore, the mass ratio of melamine to cyanuric acid is 1:1 to 1.5; the mass ratio of cyanuric acid melamine to glucose is 1:(4 to 5); and the mass ratio of MCA / G to iron salt is 1:(1 to 2).

[0053] Furthermore, the calcination temperature is 800°C, and the heating rate is 5°C / min. -1 The calcination time is 2.5 to 3.5 hours.

[0054] Furthermore, the In2S3 / MoS2@Fe-CNTs material composited on the ITO matrix is ​​obtained by making the In2S3 / MoS2@Fe-CNTs suspension fully contact the ITO glass electrode and then drying it.

[0055] Furthermore, the complete contact is achieved through immersion or coating.

[0056] Further, the concentration of the In2S3 / MoS2@Fe-CNTs suspension is 4.5–5.5 mg / mL. More preferably, it is 5 mg / mL.

[0057] The targeting aptamer bonded to the In2S3 / MoS2@Fe-CNTs material is obtained by immersing the In2S3 / MoS2@Fe-CNTs material composited on an ITO matrix into a targeting aptamer solution.

[0058] Furthermore, the immersion temperature is 4°C and the immersion time is 30 minutes.

[0059] Furthermore, the concentration of the targeting aptamer solution is 50–200 nM.

[0060] Furthermore, the Fe-CNTs material composited on the ITO glass substrate is obtained by bringing a Fe-CNTs suspension into complete contact with the ITO glass electrode and then drying it. This composite method is the same as that used for the In2S3 / MoS2@Fe-CNTs material composited on the ITO substrate.

[0061] BSA is incorporated into the photocathode, and further, the concentration of the BSA is 1 to 1.5% by mass.

[0062] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0063] I. Specific embodiments of the In2S3 / MoS2@Fe-CNTs heterojunction photoactive material and its preparation method of the present invention are as follows:

[0064] Example 1

[0065] The preparation method of the In2S3 / MoS2@Fe-CNTs heterojunction photoactive material in this embodiment adopts the following steps:

[0066] (1) Preparation of Fe-CNTs: 0.5 g of melamine and 0.51 g of cyanuric acid were dissolved in 20 mL and 10 mL of dimethyl sulfoxide, respectively, to form transparent solutions. The two solutions were then mixed for 10 minutes under vigorous stirring. After a white precipitate was formed, the mixture was centrifuged and washed several times with ethanol. The precipitate was then dried at 60 °C to obtain the final product: supramolecular cyanuric acid melamine (MCA) aggregates. Next, MCA (0.1 g) and glucose (0.4 g) were simultaneously dispersed in 60 mL of deionized water. A homogeneous suspension was formed by sonication and stirring. The resulting suspension was then transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and reacted at 180 °C for 10 hours. The resulting brown product was filtered and dried to obtain a mixed MCA / glucose precursor (MCA / G). Subsequently, 1 g of MCA / G and 1 g of FeCl3·6H2O were simultaneously dispersed in 100 mL of deionized water and reacted together for 24 hours. The mixture was then freeze-dried to form Fe-doped aggregates. 3+ MCA / glucose (MCA / G-Fe) 3+ Finally, MCA / G-Fe 3+ The powder was transferred to a tube furnace and heated at 800°C for 5°C / min under a nitrogen atmosphere. -1 Calcination was carried out for 3 hours, and the obtained sample was naturally cooled to room temperature to obtain Fe-CNTs.

[0067] (2) Synthesis of In2S3 / MoS2@Fe-CNTs: 50 mg InCl3·4H2O and 50 mg PMo 12Solution I was obtained by dissolving 10 mg of Fe-CNTs in 10 mL of deionized water and stirring for 5 min. Solution II was obtained by dissolving 10 mg of TAA in 10 mL of deionized water and stirring for 5 min. Solution III was obtained by dissolving 100 mg of TAA in 20 mL of ethanol and stirring at room temperature for 30 min. Then, solutions I, II, and III were completely mixed in a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and reacted at 200 °C for 12 h. The precipitate was collected and washed three times with deionized water and ethanol, respectively. Finally, the washed product was dried in a vacuum drying oven at 60 °C for 12 h to obtain black In2S3 / MoS2@Fe-CNTs.

[0068] In this embodiment, the In2S3 / MoS2@Fe-CNTs heterojunction photoactive material is the black In2S3 / MoS2@Fe-CNTs obtained in step (3).

[0069] II. Specific embodiments of the self-powered aptamer sensor based on the In2S3 / MoS2@Fe-CNTs heterojunction of the present invention are as follows:

[0070] Example 2

[0071] The fabrication method of the self-powered aptamer sensor based on the In2S3 / MoS2@Fe-CNTs heterojunction in this embodiment adopts the following steps:

[0072] (1) Fabrication of the photocathode: First, the indium tin oxide (ITO) glass electrode was modified using In2S3 / MoS2@Fe-CNTs obtained in Example 1. The specific steps were as follows: the ITO glass electrode was washed with acetone, ethanol, and deionized water under ultrasonic conditions. Then, the exposed geometric area was 0.25 cm². 2 30 μL of In2S3 / MoS2@Fe-CNTs suspension (5 mg / mL) was coated on an ITO glass substrate, and the resulting electrode was dried at 60 °C, which is referred to as In2S3 / MoS2@Fe-CNTs / ITO electrode;

[0073] Then, the In2S3 / MoS2@Fe-CNTs / ITO was immersed in a Staphylococcus aureus targeting aptamer solution (100 nM) and soaked at 4 °C for 30 min to obtain the modified electrode, which was labeled as Apt / In2S3 / MoS2@Fe-CNTs / ITO electrode.

[0074] Finally, the electrode was treated with BSA (1%) to dissociate nonspecific absorption and named the BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO electrode.

[0075] The sequence of the Staphylococcus aureus targeting aptamer is as follows: 5'-GCA ATG GTA CGG TAC TTCCTC GGC ACG TTC TCA GTA GCG CTC GCT GGT CAT CCC ACA GCT ACG TCA AAA GTG CACGCT ACT TTG CTA A-3'.

[0076] (2) Fabrication of photoanode: The photoanode was prepared using a method similar to that used for the In2S3 / MoS2@Fe-CNTs / ITO electrode, i.e., the ITO glass electrode was modified with Fe-CNTs (5mg / mL) prepared in Example 1 to obtain the Fe-CNTs / ITO photoanode.

[0077] The self-powered aptamer sensor based on the In2S3 / MoS2@Fe-CNTs heterojunction in this embodiment includes the photocathode and photoanode prepared in this embodiment.

[0078] III. Experimental Examples

[0079] The In2S3 / MoS2 hybrid in the experimental examples of this invention was prepared using the following steps:

[0080] 50 mg InCl3·4H2O and 50 mg phosphomolybdic acid hydrate (PMo) 12 The black In₂S₃ / MoS₂ powder was dissolved in 20 mL of deionized water and stirred for 5 minutes. Then, 100 mg of thioacetamide (TAA) was dissolved in 20 mL of ethanol and stirred at room temperature for 30 minutes. The resulting mixture was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and reacted at 200 °C for 12 hours. The precipitate was collected by centrifugation and then washed three times with deionized water and ethanol, respectively. Finally, the black In₂S₃ / MoS₂ powder was dried in a vacuum drying oven at 60 °C for 12 hours.

[0081] The light used for photocatalysis in the experimental example was visible light from a 300W xenon lamp equipped with a cutoff filter (420nm).

[0082] Example 1: Surface morphology and chemical structure characterization of In2S3 / MoS2@Fe-CNTs nanohybrids

[0083] (1) The surface morphology and structure of the In2S3 / MoS2 prepared in Example 1 were studied using scanning electron microscopy and transmission electron microscopy. The results are as follows: Figure 1 As shown.

[0084] in, Figure 1 The results show that In2S3 / MoS2 is composed of a large number of nanoflowers that are loosely stacked together. Figure 1b shows that the In2S3 / MoS2 nanoflowers are composed of fungus-like nanosheets crowded into a wrinkled shape. Figure 1 c and 1d (TEM images) also demonstrate similar results, further confirming the nanosheet structure of In2S3 / MoS2. High-resolution transmission electron microscopy images (…) Figure 1 In e), two distinct lattice spacings of 0.247 nm and 0.62 nm, belonging to In₂S₃ and molybdenum disulfide respectively, were observed. This finding indicates that PMo-doped PMo was simultaneously obtained using a hydrothermal method. 12 In₂S₃ and molybdenum disulfide. Furthermore, energy-dispersive X-ray spectroscopy (EDX) elemental mapping images of In₂S₃ (… Figure 1 f) shows that the In, Mo, S, O, P, N, and C elements are evenly distributed, indicating the formation of hybrids.

[0085] (2) The surface morphology and structure of the Fe-CNTs prepared in Example 1 were studied using scanning electron microscopy and transmission electron microscopy. The results are as follows: Figure 2 As shown.

[0086] like Figure 2 As shown in figure a, SEM images reveal the nanotube shape of Fe-CNTs, with a length of 2-5 μm. Figure 2 b further reveals the hollow structure of Fe-CNTs, as shown in the transmission electron microscope image ( Figure 2 c) confirms this. Figure 2 c verified that the multiwalls are interwoven, with some black spots embedded in the locations of the internal Fe-CNTs. Figure 2 d). In HR-TEM images ( Figure 2 A clear spacing of 0.20 nm can be found in e), which is attributed to the (110) crystal plane of metallic Fe. These phenomena indicate the use of Fe 3+ A catalyst was used to catalyze a carbon precursor to prepare multi-walled carbon nanotubes embedded with Fe nanoparticles. This iron-doped carbon nanotube structure is beneficial for improving electrochemical activity. EDX elemental mapping image of Fe-CNTs (…). Figure 2 f) shows that the Fe, C, N, and O elements are evenly distributed.

[0087] (3) The surface morphology and structure of the In2S3 / MoS2@Fe-CNTs prepared in Example 1 were studied using scanning electron microscopy and transmission electron microscopy. The results are as follows: Figure 3 As shown.

[0088] Figure 3 The image shows that In2S3 / MoS2@Fe-CNTs are nanorods encapsulated by a large number of nanosheets. Figure 3 b), and some independent nanoflowers. TEM image of In2S3 / MoS2@Fe-CNTs ( Figure 3 (c and 3d) further confirm this finding. These results indicate that In2S3 / MoS2 nanosheets are grown in situ around Fe-CNTs, resulting in a 1D / 2D heterostructure. (See HR-TEM images). Figure 3 As shown in e), molybdenum disulfide exhibits a distinct lattice spacing of 0.247 nm due to the (311) crystal plane of In2S3 / MoS2, while the 0.62 nm lattice spacing is attributed to the (002) crystal plane of molybdenum disulfide. However, the Fe crystalline phase is not observed in the HR-TEM images of In2S3 / MoS2@Fe-CNTs, primarily due to the complete coverage of 1D Fe-CNTs by In2S3 / MoS2 nanosheets, which will be further described in the EDX elemental mapping images. Figure 3 As can be seen from f, in the EDX elemental mapping image of In2S3 / MoS2@Fe-CNTs, Fe, In, Mo, and S elements are uniformly distributed in the selected region, while the distribution of O, N, P, and C elements is not significant.

[0089] In addition, the EDX spectra of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs prepared in Example 1 were measured, and the results are as follows: Figure 4 As shown.

[0090] EDX spectrum of In2S3 / MoS2 ( Figure 4 a) shows that the atomic contents of In, Mo, and S are 3.42%, 4.27%, and 13.32%, respectively, and the atomic contents of P, N, O, and C are 0.84%, 7.51%, 24.21%, and 46.43%, respectively; the EDX spectrum of Fe-CNTs ( Figure 4 b) shows that the atomic contents of Fe, N, O, and C are 0.8%, 13.66%, 14.07%, and 71.43%, respectively; the EDX spectrum of In2S3 / MoS2@Fe-CNTs ( Figure 4 c) shows that the atomic contents of In, Mo, and S are 2.99%, 2.96%, and 8.17%, respectively, while the atomic contents of Fe and C are 0.83% and 51.18%, respectively.

[0091] (4) The crystal structures and chemical compositions of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs were analyzed using different characterization methods, and the results are as follows: Figure 5 As shown.

[0092] Figure 5Curve i shows that the characteristic peaks at 2θ = 27.5° and 47.9° belong to the (311) and (440) crystal planes of In2S3 (JCPDS-650459), while 2θ = 33.4° belongs to the (002) plane of molybdenum disulfide, further verifying the combination of In2S3 and molybdenum disulfide phases. The XRD pattern of Fe-CNTs (curve ii) includes characteristic peaks at 2θ = 43.4° and 44.7°, corresponding to the (102) crystal plane of Fe3C and the (110) crystal plane of metallic Fe, respectively; in addition, a broad peak at 2θ = 26.4° is due to (002) graphitic carbon, a finding that reveals the successful doping of iron components into carbon nanotubes. In the XRD pattern (curve iii) of In2S3 / MoS2@Fe-CNTs, only characteristic peaks of In2S3 and molybdenum disulfide were observed, indicating that In2S3 / MoS2 NSs completely covered the Fe-CNTs surface.

[0093] like Figure 5 As shown in curve b (i), at 370cm -1 and 405cm -1 The characteristic peaks observed at these locations are attributed to the A peaks of In2S3. 1g Pattern and molybdenum disulfide A 1g Pattern. Fe-CNTs ( Figure 5 b, curve ii) and In2S3 / MoS2@Fe-CNTs ( Figure 5 b, the Raman spectra of curve iii) at 1342 and 1586 cm⁻¹ -1 The presence of d-band and g-band is clearly visible, further proving the existence of carbon nanotubes.

[0094] (5) The N2 adsorption-desorption isotherms and pore size distribution curves of In2S3 / MoS2, Fe-CNTs and In2S3 / MoS2@Fe-CNTs in Example 1 were determined, and the results are as follows: Figure 6 As shown.

[0095] Depend on Figure 6 It can be seen that the In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs samples exhibit type IV adsorption-desorption isotherms with hysteresis loops, indicating their mesoporous structure. The BET specific surface area of ​​In2S3 / MoS2 is 58 m². 2 g -1 The specific surface area of ​​Fe-CNTs is 135 m². 2 g -1 The specific surface area of ​​In2S3 / MoS2@Fe-CNTs is 60 m². 2 g -1 .

[0096] (6) The chemical structures and compositions of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs were investigated using X-ray photoelectron spectroscopy (XPS), and the results are as follows: Figure 7 As shown.

[0097] Figure 7 In Figure a, curve i (In₂S₃ / MoS₂) shows the signals of In 3d (444.9 eV), Mo 3d (228.2 eV), S 2p (161.4 eV), C 1s (284.4 eV), and O 1s (531.6 eV). Curve ii (Fe-CNTs) shows the signals of C 1s (284.4 eV), O 1s (531.6 eV), and Fe 2p (710.1 eV). The chemical composition and environment of each element change after the In₂S₃ / MoS₂ nanosheets surround Fe-CNTs. Curve iii (In2S3 / MoS2@Fe-CNTs) shows the signals of In 3d (444.9 eV), Mo 3d (228.2 eV), S 2p (161.4 eV), C 1s (284.4 eV), N 1s (394.4 eV) and O 1s (531.6 eV).

[0098] like Figure 7 As shown in b, the In 3d XPS spectrum of In2S3 / MoS2@Fe-CNTs has two clear peaks at binding energies (BE) of 444.9 eV and 452.5 eV, which belong to In 3d... 5 / 2 and In 3d 3 / 2 Mo 3d XPS spectrum ( Figure 7 c) It can be divided into multiple peaks, including M–S (225.9 eV), Mo 4+ (3d 5 / 2 (228.5eV) and 3d 3 / 2 (231.7eV), Mo 5+ (229.7eV), Mo 6+ (233eV) and MoO x (235.5 eV). The Mo-S bonds are caused by molybdenum disulfide, while MoO... x The presence of [missing information] indicates partial oxidation of Mo. The mixed valence of Mo further promotes electron transfer and photoadsorption capabilities. Furthermore, high-resolution S2p XPS spectra ([missing information]) Figure 7 d) can be divided into S 2- S 2p 3 / 2 (161.2 eV) and S 2p 1 / 2 (162.4 eV) Two main components, in S2 2- S 2p 3 / 2There is a peak at BE (163.7 eV). Additionally, two other peaks can be observed at BEs of 166.85 and 168.9 eV, which are due to SO. x This discovery reveals the slight oxidation of sulfur during the bonding process of In₂S₃ / MoS₂ and Fe-CNTs under hydrothermal conditions. Furthermore, Figure 7 e shows the C1s XPS spectra, including C=C (284.2 eV), C–C (284.9 eV), C–O (285.9 eV), and COO (288.6 eV). In2S3 / MoS2@Fe-CNTs ( Figure 7 The O1s XPS spectrum of f) yields three parts: Mo-O (530.7 eV), C=O (531.8 eV), and C–O (532.9 eV). Increasing the oxygen vacancy content can greatly improve the photocatalytic ability.

[0099] Experimental Example 2: Optical properties and charge transfer mechanism of In2S3 / MoS2@Fe-CNTs

[0100] To further investigate vacancy defects, we measured electron paramagnetic resonance (EPR) spectra (…). Figure 8 a) Compared with In2S3 / MoS2 and Fe-CNTs, In2S3 / MoS2@Fe-CNTs, combined with multiple components (In2S3, molybdenum disulfide, Fe and C), significantly enhanced the EPR response at g = 2.003, indicating the generation of many S vacancy defects, which is beneficial to improving photocatalytic activity.

[0101] Figure 8 b. The light absorption characteristics of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs samples were shown by UV-Vis absorption spectroscopy. In2S3 / MoS2 has an absorption edge around 450 nm, while Fe-CNTs exhibit good full-spectrum absorption. The absorption edge of In2S3 / MoS2@Fe-CNTs extends to approximately 490 nm, and the heterojunction formed by In2S3 / MoS2 and Fe-CNTs shows enhanced visible light trapping capability.

[0102] Band gap energy (E) g ) is composed of (αhν) 2 With hν( Figure 8 c) Determined. The band gap energies of In2S3 / MoS2, Fe-CNTs, and In2S3 / MoS2@Fe-CNTs are 2.74, 2.50, and 2.62 eV, respectively. Compared with In2S3 / MoS2, the EV of In2S3 / MoS2@Fe-CNTs is... g The decrease further indicates a wider visible light response range.

[0103] Electrochemical impedance spectroscopy (EIS) was performed using a conventional three-electrode system and a CHI660D electrochemical analyzer to study the electron transfer rate. The results are as follows: Figure 8 As shown in d, this three-electrode system consists of an ITO working electrode modified with photoactive materials (In₂S₃ / MoS₂, Fe-CNTs, or In₂S₃ / MoS₂@Fe-CNTs), an Ag / AgCl (saturated potassium chloride) reference electrode, and a platinum wire pair electrode. The electrolyte is a solution containing 5 mM [Fe(CN)₆]. 3- / 4- The PBS buffer solution (0.1M, pH=7.4) was used, and the voltage was supplied through an external power source. As shown in the figure, the simulated charge transfer resistance (R0) of In2S3 / MoS2@Fe-CNTs (121.7Ω) is... ct The Ω value is smaller than that of In2S3 / MoS2 (283.5 Ω) and Fe-CNTs (998.1 Ω), indicating a faster electron transfer rate. These results show that integrating two-dimensional In2S3 / MoS2 nanosheets onto the surface of one-dimensional Fe-CNTs can improve light absorption, prolong the lifetime of photoinduced charge carriers, improve the separation efficiency of photogenerated electron-hole pairs, and increase electron transfer.

[0104] In addition, the Mott-Schottky plot of In2S3 / MoS2 ( Figure 9 a) has a negative slope, indicating p-type semiconductor properties, while Fe-CNTs ( Figure 9 b) The positive slope indicates that it is an n-type semiconductor, indicating that a pn junction has been formed.

[0105] Experimental Example 3: Construction of a self-powered self-sensor driven by an In2S3 / MoS2@Fe-CNTs and Fe-CNTs dual-photoelectrode photocatalytic fuel cell.

[0106] (1) Using the Fe-CNTs / ITO electrode prepared in Example 2 as the photoanode and pnIn2S3 / MoS2@Fe-CNTs / ITO as the photocathode, a single-chamber cell was constructed, and its photocurrent response was measured. The results are as follows: Figure 10 As shown.

[0107] Using a traditional three-electrode system, the amperometric current-time (It) curve was measured using a CHI660D electrochemical analyzer. The results are as follows: Figure 10 As shown in a and 10b. This three-electrode system consists of an ITO working electrode modified with photoactive materials (In2S3 / MoS2, Fe-CNTs, or In2S3 / MoS2@Fe-CNTs), an Ag / AgCl (saturated potassium chloride) reference electrode, and a platinum wire pair electrode, with PBS as the electrolyte. First, as... Figure 10As shown in a and 10b, Fe-CNTs exhibit an anodic photocurrent response, while In2S3 / MoS2 shows a significant cathodic photocurrent response under visible light. Notably, In2S3 / MoS2@Fe-CNTs exhibited a cathodic photocurrent (steady current) of 1.66 μA, which is higher than that of In2S3 / MoS2 (0.72 μA), indicating enhanced photoelectric activity of the pn heterojunction. Then, when a dual-source photocatalytic fuel cell (PFC) was constructed using In2S3 / MoS2 / ITO or In2S3 / MoS2@Fe-CNTs / ITO as the working electrode and Fe-CNTs / ITO as the counter / reference electrode, a significantly amplified photocathode current response was observed. Figure 10 c). The cathode photocurrents of In2S3 / MoS2 / ITO and In2S3 / MoS2@Fe-CNTs / ITO reached as high as 3.25 μA and 7.1 μA, respectively, indicating that the p-nIn2S3 / MoS2@Fe-CNTs junction can promote the separation of photogenerated electron-hole pairs. Electrons accumulated on In2S3 / MoS2 can be used for O2 reduction to generate water. On the other hand, photogenerated holes on the semiconductor valence band (VB) of the Fe-CNTs anode can react with water to generate O2. Electrons on the semiconductor conduction band (CB) of Fe-CNTs can be transferred to ITO, and ITO can be further transferred to the In2S3 / MoS2@Fe-CNTs / ITO cathode through an external circuit, thereby improving the signal response.

[0108] To investigate the output performance of the constructed PFC, we studied the output voltage (VI curve). Figure 11 a) and power density (PI curve, Figure 11 b) Dependence on battery current and OCP curve ( Figure 11 c).

[0109] Under visible light irradiation, the high output voltage of the PFC assembled using the In2S3 / MoS2@Fe-CNTs / ITO photocathode and Fe-CNTs / ITO anode prepared in Example 2 was 0.68V (curve iii). Figure 11 a) The maximum output power density (Pmax) is 7.3 μW cm⁻¹. -2 (Curve iii, Figure 11 b), OCP is 0.63V (curve iii), Figure 11 c), significantly higher than In2S3 / MoS2 / ITO photocathode (curve ii), Figure 11 (a, 11b, and 11c). These results further demonstrate that the In2S3 / MoS2@Fe-CNTs heterojunction possesses superior photoelectronic capabilities, which can be attributed to enhanced light absorption, good separation ability, and catalytic activity.

[0110] (2) Since the PFC assembled with In2S3 / MoS2@Fe-CNTs has high Pmax and OCP, we use it as an aptamer sensor to detect Staphylococcus aureus.

[0111] Figure 11 The data in df describes the VI, PI, and OCP-time curves of a PFC constructed using In2S3 / MoS2@Fe-CNTs / ITO, used for aptamer anchoring and Staphylococcus aureus detection. The results show that the PFC output voltage is 0.62V (curve ii, ...). Figure 11 f), Pmax is 6.6 μW cm -2 (Curve ii, Figure 11 e), OCP is 0.60V (curve ii), Figure 11 f). After aptamer immobilization (curves iii, Figs. 11d, 11e, and 11f), the output voltage, Pmax, and OCP values ​​decrease, which can be attributed to the steric hindrance of the aptamer chain. Notably, the decrease in output voltage, Pmax, and OCP values ​​at the BSA blocking electrode is negligible (curve iv). Figure 11 d, 11e, and 11f) indicate no significant nonspecific adsorption. The BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO electrode was then subjected to Staphylococcus aureus (10 CFU / mL) -1 After incubation, the output voltage, Pmax, and OCP values ​​decreased to 0.58V, 5.5μWcm, and 0.58V, respectively. -2 and 0.57V (curve v, Figure 11 (d, 11e, and 11f). This is attributed to the formation of the aptamer-Staphylococcus aureus complex, which hinders electron transfer, leading to a decrease in the potential and power density of the PFC.

[0112] Example 4: Sensing performance of Staphylococcus aureus based on In2S3 / MoS2@Fe-CNTs heterojunction aptamer sensor

[0113] Considering the variations in Pmax and OCP of the developed PFC, its applicability for self-powered bacterial detection was verified. This experimental example investigated the optimal detection conditions for constructing a self-powered sensing system, and the results are as follows: Figure 12 As shown.

[0114] according to Figure 12 It can be seen that the amount of In2S3 / MoS2@Fe-CNTs used ( Figure 12 a) is 5 mg / mL, aptamer concentration ( Figure 12 b) is 100 nM, aptamer incubation time ( Figure 12 c) is 30 min, bacterial binding time ( Figure 12d) is 30 minutes.

[0115] Under these optimal conditions, BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO-based PFCs were prepared for the selective and sensitive detection of Staphylococcus aureus, and the results are as follows: Figure 13 As shown.

[0116] Pre-experimental treatment: To detect Staphylococcus aureus, the BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO obtained in Example 2 was incubated with Staphylococcus aureus solutions of different concentrations (10, 100, 1×10⁻⁶). 3 1×10 4 , 1×10 5 , 1×10 6 , 1×10 7 (CFU / mL) were incubated at 4℃ for 30 min and labeled as S. aureus / BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO.

[0117] Figure 13 a) A series of VI curves were obtained for the developed PFC against different concentrations of bacteria. The results showed that the output voltage decreased with increasing Staphylococcus aureus concentration. Simultaneously, Pmax increased with increasing Staphylococcus aureus concentration. Figure 13 b). The change in Pmax (ΔPmax) is used as a function of bacterial concentration. Figure 13 c) It can be seen that in 10 -1 ×10 7 CFU·mL -1 Within this range, ΔPmax increases significantly with increasing bacterial concentration. When the bacterial concentration exceeds 1×10⁻⁶, ΔPmax increases evenly. 6 CFU·mL -1 At this point, the detection response of ΔPmax tends to plateau. This finding indicates that the specific binding between the aptamer and the bacteria has reached an equilibrium. In particular, given ΔPmax (μW cm⁻²) = 0.741 [lgConS.aureus (CFU·mL⁻¹)], the detection response plateaus. -1 )]–0.510 (correlation coefficient R) 2 The linear regression equation (=0.996) has a detection limit (LOD) of 1.2 CFU·mL. -1 (S / N = 3), the ΔPmax value of the self-powered sensor varies with the logarithm of the Staphylococcus aureus concentration from 10 to 1 × 10⁻⁶. 7 CFU·mL -1 It increases linearly ( Figure 13c). Similarly, LOD was assessed using OCP-time curves of different concentrations of Staphylococcus aureus via a PFC aptamer sensor. Therefore, when the ΔOCP value was taken as lgCon... S.aureus When using functions, in 10–10 7 CFU·mL -1 Within the linear range, the LOD is 1.6 CFU·mL. -1 ( Figure 13 (d and 13e). These results indicate that the LOD derived from both Pmax and OCP assessment methods is comparable, significantly lower than, or comparable to, some previously reported biosensors for Staphylococcus aureus analysis (Table 1).

[0118] Table 1 Comparison with existing Staphylococcus aureus detection technologies.

[0119]

[0120] Note: [1]

[0121] [2]H.Yang,

[0122] [3]H.Yang,H.Chen,L.Cao,H.Wang,W.Deng,Y.Tan,Q.Xie,An immunosensor forsensitive photoelectrochemical detection of Staphylococcus aureus using ZnS–Ag2S / polydopamine as photoelectric material and Cu2O as peroxidase mimic tag,Talanta 212(2020)120797.

[0123] [4]S.Luo,F.Liu,S.Gu,K.Chen,G.Yang,Y.Gu,J.Cao,L.-L.Qu,Nanozyme-mediated signal amplification for ultrasensitive photoelectrochemical sensingof Staphylococcus aureus based on Cu–C3N4–TiO2heterostructure,Biosensors andBioelectronics 216(2022)114593.

[0124] [5]E.Han,Y.Zhang,J.Cai,X.Zhang,Development of highly sensitiveimmunosensor for detection of Staphylococcus aureus based on AuPdPttrimetallic nanoparticles functionalized nanocomposite,Micromachines12(4)(2021)446.

[0125] [6]M.Roushani,Z.Rahmati,M.Golchin,Z.Lotfi,M.Nemati,Electrochemicalimmunosensor for determination of Staphylococcus aureus bacteria by IgYimmobilized on glassy carbon electrode with electrodeposited goldnanoparticles,Microchimica Acta 187(10)(2020)1-8.

[0126] [7]H.Wang,Y.Xiu,Y.Chen,L.Sun,L.Yang,H.Chen,X.Niu,Electrochemicalimmunosensor based on an antibody-hierarchical mesoporous SiO2 for thedetection of Staphylococcus aureus,RSC Advances 9(28)(2019)16278-16287.

[0127] [8]J.-Q.Wang,J.-Y.Wu,J.-Y.Lin,T.-H.Li,D.-F.Li,N.Gan,Rapid Detectionof Staphylococcus aureus by An Electrochemical Immunosensor Based on Egg YolkAntibody-Metal Organic Framework Composite Probe,Chinese Journal ofAnalytical Chemistry 49(2)(2021)197-206.

[0128] [9]C.-W.Lee,H.-Y.Chang,J.-K.Wu,F.-G.Tseng,Ultra-sensitiveelectrochemical detection of bacteremia enabled by redox-active goldnanoparticles(raGNPs)in a nano-sieving microfluidic system(NS-MFS),Biosensors&Bioelectronics 133(2019)215-222.

[0129]

[10] S.Roy,K.Bisaria,S.Nagabooshanam,A.Selvam,S.Chakrabarti,S.Wadhwa,R.Singh,A.Mathur,J.Davis,An Electroanalytical Paper-Based Wound DressingUsing ZIF-67 / C3N4 Nanocomposite Towards the Monitoring of StaphylococcusAureus in Diabetic Foot Ulcer,IEEE Sensors Journal 21(2)(2021)1215-1221.

[0130]

[11] S.Ranjbar,S.Shahrokhian,Design and fabrication of anelectrochemical aptasensor using Au nanoparticles / carbon nanoparticles / cellulose nanofibers nanocomposite for rapid and sensitive detection ofStaphylococcus aureus,Bioelectrochemistry 123(2018)70-76.

[0131]

[12] Y.Lou, Q.Jia, F.Rong, S.Zhang, Z.Zhang, M.Du, Universal biosensing platform based on polyMn-MOF nanosheets for efficient analysis of foodbornepathogens from diverse foodstuffs, Food Chemistry395(2022)133618.

[0132]

[13] X. Xue, J. Pan, H.

[0133]

[14] P. Liu, L. Han, F. Wang, VA Petrenko, A. Liu, Gold nanoprobe functionalized with specific fusion protein selection from phage display and its application in rapid, selective and sensitive colorimetric biosensing of Staphylococcus aureus, Biosensors and Bioelectronics 82 (2016) 195-203.

[0134] Experiment 5 determined the selectivity, reproducibility, stability, and reproducibility of the aptamer sensor based on the In2S3 / MoS2@Fe-CNTs heterojunction.

[0135] (1) This experimental example uses different analytes as interfering agents to evaluate the selectivity of the In2S3 / MoS2@Fe-CNTs-based self-powered aptamer sensor for detecting Staphylococcus aureus. The results are as follows: Figure 14As shown in Figure a, the analytes include foodborne bacteria (Escherichia coli, Bacillus subtilis, Streptococcus typhimurium) and metal ions (magnesium sulfate, C6H5COONa, sodium chloride, and potassium nitrate), as well as mixtures thereof with Staphylococcus aureus.

[0136] The concentration of each metal ion interfering agent was 1 ng·mL. -1 The concentration of other foodborne bacteria was set at 1×10⁻⁶. 3 CFU·mL -1 The level of Staphylococcus aureus (10 CFU / mL) -1 100 times that of ).

[0137] like Figure 14 As shown in Figure a, the P caused by interference analysis using a developed self-powered aptamer sensor is illustrated. max The change in the value was not significant. In contrast, the ΔP inferred from the detection of Staphylococcus aureus... max The response was significantly higher than that of interfering substances and comparable to that of mixture analysis. The superior selectivity of the fabricated aptamer is mainly attributed to the specific recognition of Staphylococcus aureus by the aptamer immobilized on the In2S3 / MoS2@Fe-CNTs / ITO electrode.

[0138] (2) In this experimental example, six BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO electrodes were also constructed to study the reproducibility of the aptamer sensor. Figure 14 As shown in b, the detection response (ΔP) of the six independent aptamer sensors to Staphylococcus aureus. max The results are quite close, with a relative standard deviation (RSD) of 1.78%. These results reveal the outstanding reproducibility of the self-powered aptamer sensor.

[0139] (3) In this experiment, the storage stability of the aptamer sensor was tested by measuring the output voltage and power density every day for 15 consecutive days.

[0140] The storage stability of the self-powered aptamer sensor was investigated on the same Apt / In2S3 / MoS2@Fe-CNTs / ITO electrode and was measured seven times consecutively. Figure 14 c describes the low RSD (1.46%) in ΔPmax for the detection of Staphylococcus aureus by the same aptamer sensor, demonstrating the good stability of the proposed self-powered aptamer sensor.

[0141] (4) This experimental example also calculated the regeneration capability of the self-powered aptamer sensor developed.

[0142] For aptamer sensor regeneration, *S. aureus* / BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO was immersed in 0.1M sodium hydroxide for 3 min, thoroughly washed with 0.01M PBS, and then *S. aureus* (10 CFU / mL) was measured using a renewed BSA / Apt / In2S3 / MoS2@Fe-CNTs / ITO electrode. -1 Repeat 7 times.

[0143] Figure 14 Figure d shows that the Pmax and OCP values ​​of the regenerated Apt / In2S3 / MoS2@Fe-CNTs / ITO are comparable to those of the initial construction. When using the regenerated aptamer sensor to detect Staphylococcus aureus, the obtained Pmax response recovered to the initial value. The entire cycle was repeated 7 times, and the Staphylococcus aureus detection signal only decreased slightly. This study demonstrates that the prepared aptamer sensor has good regeneration capability for the analysis of Staphylococcus aureus. Due to these outstanding adaptability, the developed self-powered aptamer sensor has great application potential.

[0144] IV. Specific embodiments of the application of the self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction of the present invention in foodborne bacteria are as follows:

[0145] Experiment 6 determines the suitability of aptamer sensors based on In2S3 / MoS2@Fe-CNTs heterojunctions.

[0146] To evaluate the applicability of the aptamer sensor, the constructed In2S3 / MoS2@Fe-CNTs-based aptamer sensor was used to analyze Staphylococcus aureus in real samples of milk and bread. The results are shown in Tables 2 and 3.

[0147] Experimental pretreatment: (1) Before use, treat milk (10 mL) with 0.2 mL sodium hydroxide (0.1 M) and 0.8 mL acetonitrile. Then, centrifuge at 5000 rpm for 5 min at room temperature, collect the supernatant, dilute it 50 times with PBS (0.01 M, pH = 7.4), and store at 4℃ for use.

[0148] (2) Grind the bread (5mg), mix it with 5mL PBS, and then sonicate it for 1 hour. Then centrifuge the sample at 1000rpm for 5min at room temperature, collect the supernatant, and dilute it 100 times with 0.01M PBS.

[0149] (3) Add Staphylococcus aureus suspensions of different concentrations to the milk and bread supernatant respectively to form actual sample solutions for detection.

[0150] As shown in Tables 2 and 3, the recoveries for milk samples ranged from 93.33% to 107.89% (RSDs from 1.20% to 4.36%), while the recoveries for bread samples ranged from 96.49% to 103.42% (RSDs from 0.77% to 3.30%). These results demonstrate that the constructed self-powered aptamer sensor is feasible for determining Staphylococcus aureus in real food samples.

[0151] Table 2. Determination of Staphylococcus aureus in milk using a self-powered aptamer sensor (n=3)

[0152]

[0153] Table 3. Determination of Staphylococcus aureus in bread using a self-powered aptamer sensor (n=3)

[0154]

Claims

1. A self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction, characterized in that, The invention includes a photocathode based on an In2S3 / MoS2@Fe-CNTs heterojunction photoactive material and a photoanode based on Fe-CNTs. The photocathode comprises an electrode substrate, an In2S3 / MoS2@Fe-CNTs material composited on the electrode substrate, and an aptamer targeting foodborne bacteria bound to the In2S3 / MoS2@Fe-CNTs material. The In2S3 / MoS2@Fe-CNTs heterojunction photoactive material comprises a Fe-doped carbon nanotube substrate and In2S3 / MoS2 hybrid nanosheets attached to a Fe-doped CNTs substrate.

2. The self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction according to claim 1, characterized in that, The Fe-doped carbon nanotube matrix is ​​an n-type semiconductor, and the In2S3 / MoS2 hybrid nanosheet is a p-type semiconductor, forming a pn junction.

3. The self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction according to claim 1 or 2, characterized in that, The preparation method of the In2S3 / MoS2@Fe-CNTs heterojunction photoactive material includes the following steps: in-situ generation of In2S3 / MoS2 hybrid nanosheets on Fe-doped carbon nanotubes to obtain In2S3 / MoS2@Fe-CNTs.

4. The self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction according to claim 3, characterized in that, The in-situ generation includes: a solvothermal reaction of indium salt, phosphomolybdic acid, sulfide and Fe-doped carbon nanotubes in a solvent.

5. The self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction according to claim 4, characterized in that, The amount of indium salt added is 4 to 6 times the mass of Fe-doped carbon nanotubes, the amount of phosphomolybdic acid added is 4 to 6 times the mass of Fe-doped carbon nanotubes, and the amount of sulfide added is 8 to 12 times the mass of Fe-doped carbon nanotubes.

6. The self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction according to claim 5, characterized in that, The indium salt is InCl3, and the sulfide is thioacetamide.

7. The self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction according to claim 5, characterized in that, The temperature of the thermal reaction is 190~210℃, and the reaction time is 10~16h.

8. The self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction according to claim 1 or 2, characterized in that, The foodborne bacteria is Staphylococcus aureus.

9. An application of a self-powered aptamer sensor based on In2S3 / MoS2@Fe-CNTs heterojunction in the detection of foodborne bacteria, characterized in that, Foodborne bacteria in a sample can be detected using the self-powered aptamer sensor based on an In2S3 / MoS2@Fe-CNTs heterojunction as described in any one of claims 1 to 8.

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