An AuPt@NP5 / BiOI-MoS2 composite photoelectric material and its preparation method and application

Abstract

The present application discloses an Au@NP5 / BiOI‑MoS2 composite photoelectric material and its preparation method and application, wherein Pt is modified on Au, a layer of biamino pillar[5]arene is coated on the surface of AuPtNPs, and AuPt@NP5 is used as a photoactive material to design a novel signal switching type photoelectrochemical (PEC) biosensor system for detecting carcinoembryonic antigen. The excellent conductivity of the AuPt bimetallic material is utilized; the host-guest complexation between pillar[5]arene NP5 and the AA electron donor is utilized; the high mobility of MoS2 and the moderate band gap of BiOI help to improve the separation efficiency of photogenerated electrons and holes and reduce the recombination probability. Based on the multiple signal amplification capabilities of AuPt@NP5 / BiOI‑MoS2, the electrode exhibits an excellent linear range when detecting carcinoembryonic antigen.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectrochemical technology, and specifically relates to an AuPt@NP5 / BiOI-MoS2 composite photoelectric material and a preparation method and application thereof. Background Art

[0002] Carcinoembryonic antigen (CEA) is a glycoprotein that is widely present in patients with various malignant tumors. As an important tumor marker, CEA plays a vital role in the early screening, diagnosis and prognosis evaluation of various tumors. In normal adult tissues, the expression level of CEA is usually very low, but in certain types of cancer, such as colorectal cancer, pancreatic cancer, gastric cancer and lung cancer, the expression level of CEA can be significantly increased. The detection of CEA can not only be used for early screening and diagnosis of cancer, but also for monitoring the treatment effect and recurrence of cancer patients. Therefore, accurately measuring the concentration of CEA is of great research significance for the early detection and treatment of cancer. Therefore, it has become very important to develop a detection technology that can quickly analyze CEA.

[0003] At present, there are many methods for detecting CEA, such as electrochemiluminescence, electrochemical sensors, colorimetric detection, fluorescence detection, photoelectrochemical sensors, etc. Photoelectrochemical sensors combine optical and electrochemical technologies. They use light to activate photosensitive materials to generate electrons, which further accelerates the electron transfer between the analyte and the electrode. Photoelectrochemical sensors have the advantages of high sensitivity, simple operation, and fast detection speed, and show great potential in CEA detection. Pillar aromatics, as a new generation of macrocyclic host compounds, have unique structures and hydrophobic cavities compared to the previous four generations. They can recognize and selectively encapsulate specific molecules or ions and show excellent performance in host-guest complexation. With the expansion of the application range of columnar aromatics[5], researchers have carried out various chemical modifications on their groups. By introducing different functional groups, columnar aromatics can be customized in terms of solubility, recognition ability and self-assembly behavior.

[0004] Metal nanomaterials, with their unique physicochemical properties, excellent biocompatibility, and ease of modification, play a vital role in scientific research and practical applications. Gold (Au) and platinum (Pt) are both excellently conductive metal nanomaterials. Their surfaces are easily chemically modified, allowing them to bind various biomolecules or chemical probes, enhancing the selectivity and specificity of sensors. Compared to single metal materials, bimetallic materials are less susceptible to toxic substances and maintain long-term stability. The synergistic effect between the two metals can significantly enhance photoelectrochemical activity.

[0005] BiOI (band gap approximately 1.8 eV) has a layered structure, with each layer composed of Bi and I units, with Bi and I atoms alternating to form two-dimensional planes connected by O atoms. Bi's electronic structure plays a key role in reducing the band gap and enhancing visible light absorption. However, its high photoelectric charge recombination rate limits its application in photoelectric sensing. To address this issue, researchers have conducted extensive material modification efforts, including element doping, heterostructure construction, and surface modification, to improve light absorption efficiency and promote the efficient separation and transport of photogenerated electron-hole pairs. Among many transition metals, molybdenum disulfide (MoS2) possesses a unique layered structure and excellent physicochemical properties. It is composed of stacked S-Mo-S atomic layers, interconnected by van der Waals forces and held together by strong covalent bonds. This layered structure endows MoS2 with excellent light absorption and photoelectric conversion capabilities. The band gap of multilayer MoS2 is about 1.2eV. When combined with BiOI, it forms a cross-band gap structure, which can promote the separation of photogenerated electrons and holes and reduce the probability of carrier recombination. The high conductivity of MoS2 is conducive to the rapid transfer of photogenerated electrons, while BiOI is conducive to the effective separation of photogenerated holes. Therefore, an AuPt@NP5 / BiOI-MoS2 heterojunction composite photoelectrochemical sensor system is designed. It utilizes the excellent conductivity of AuPt bimetallic, the host-guest complexation between pillar[5]arene NP5 and AA (electron donor), the high mobility of MoS2 and the moderate band gap of BiOI to help improve the separation efficiency of photogenerated electrons and holes, reduce the recombination probability, and increase the photocurrent signal.

[0006] Therefore, it is expected that the designed AuPt@NP5 / BiOI-MoS2 composite photoelectric material immunosensor will open up a new way to detect carcinoembryonic antigen and provide an efficient and sensitive tool for early cancer detection and monitoring. Summary of the Invention

[0007] Technical problems solved: This application addresses the shortcomings of the existing technology and solves the technical problems of low sensitivity, limited detection range, expensive instruments, requirement of specialized operators, low efficiency, slow speed, and difficulty in operation of the original detection technology. It provides an AuPt@NP5 / BiOI-MoS2 composite photoelectric material and its preparation method and application.

[0008] Technical solution: To achieve the above objectives, this application is implemented through the following technical solutions:

[0009] A method for preparing an AuPt@NP5 / BiOI-MoS2 composite photoelectric material comprises modifying molybdenum disulfide on bismuth oxyiodide by an in-situ growth method to form a BiOI-MoS2 heterojunction, then functionalizing NP5 into bimetallic nanoparticles AuPt@NP5, and distributing them on the BiOI-MoS2 heterojunction to prepare the AuPt@NP5 / BiOI-MoS2 composite photoelectric material. The method specifically comprises the following steps:

[0010] The first step is to prepare NP5 with a double amino column [5] aromatic hydrocarbon: ;

[0011] The second step is to prepare Au NPs: using chloroauric acid as the raw material and citric acid and sodium citrate as reducing agents, a spherical gold nanoparticle solution is prepared by a thermal reduction method. The dosage ratio of the chloroauric acid, citric acid, and sodium citrate is 1 to 1.3 mL of 25.4 mM chloroauric acid: 0.9 to 1.2 mL of 0.1 M citric acid: 2.1 to 2.8 mL of 0.1 M sodium citrate;

[0012] Step 3: Synthesize AuPt NPs by seed growth method: 200-400 μL of Au NPs were diluted in 800-1600 μL of ultrapure water containing 20 wt% polyvinylpyrrolidone (PVP) by volume, and then maintained at 37°C-40°C for 5-10 min to stabilize the Au NPs solution; 40-80 μL of 100 mg / mL L-ascorbic acid and 40-80 μL of chloroplatinic acid were mixed with the Au NPs solution and immediately heated at 65-70°C and stirred at 600-800 rpm for 1-1.2 h, until the color of the solution changed from red to brown and then to black, indicating successful Pt deposition; centrifuged at 1000-1200 rpm for 15-20 min, and washed three times with ultrapure water to remove excess reagents to obtain spherical amber nanoparticle solution AuPt NPs;

[0013] Step 4: Disperse 2 to 2.5 mg of NP5 in 1 to 1.2 mL of spherical amber nanoparticle solution AuPt NPs by ultrasonication according to the mass-to-volume ratio and ultrasonicate for 30 to 35 minutes to synthesize AuPt@NP5 composite photoelectric material;

[0014] In the fifth step, flower-like BiOI was prepared by a one-pot hydrothermal method: 0.485-0.97 g Bi(NO₃)₃·5H₂O was first dissolved in 30-60 mL of a mixed solution of water and ethylene glycol according to the mass-to-volume ratio and ultrasonicated for 5-10 min to obtain a transparent solution. Subsequently, 0.166-0.332 g polyvinylpyrrolidone (PVP) was added and stirred for 30-35 min. Then, 0.119-0.238 g potassium bromide (KBr) was added and stirred for 30-35 min. The mixture was then heated in an autoclave at 160-180°C for 180-200 min. The product was centrifuged three times at 6000-8000 rpm for 5-10 min in ethanol and ultrapure water, respectively. Finally, the centrifuged sample was freeze-dried and the orange-red powder of BiOI, i.e., flower-like BiOI, was collected for further use.

[0015] Step 6: Prepare BiOI-MoS2 heterojunction by in situ growth method: dissolve 0.05-0.2 g sodium molybdate in 60-80 mL ultrapure water according to the mass-to-volume ratio, then add 0.0375-0.15 g thioacetamide, and stir the mixture vigorously for 1-1.2 h to ensure homogeneity; add 0.09-0.36 g BiOI to the vigorously stirred solution, continue stirring for 4-4.2 h, and then heat it in an autoclave at 180-200 ° C for 24-26 h. The product is centrifuged three times at 8000-10000 rpm for 5-10 min with ultrapure water; finally, freeze-dry the sample to obtain BiOI-MoS2 heterojunction;

[0016] Step 7: AuPt@NP5 / BiOI-MoS2 was synthesized by physical adsorption method: 2 ~ 2.5 mL of AuPt@NP5 composite photoelectric material prepared in the fourth step was dropwise added into 1.5 ~ 2 mg of BiOI-MoS2 heterojunction prepared in the sixth step according to the mass volume ratio, and stirred at 600 ~ 800 rpm for 5 ~ 10 min to obtain AuPt@NP5 / BiOI-MoS2 heterojunction, i.e., AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

[0017] Furthermore, the specific steps of preparing the spherical gold nanoparticle solution by the thermal reduction method in the second step are: adding 0.9 to 1.2 mL of 0.1 M citric acid and 2.1 to 2.8 mL of 0.1 M sodium citrate to 150 to 200 mL of boiling water, stirring at 500 to 700 rpm for 15 to 20 minutes; then adding 1 to 1.3 mL of 25.4 mM chloroauric acid, stirring at 500 to 700 rpm for 3 to 5 minutes, and then cooling in ice water. The obtained precipitate is washed with ultrapure water and ethanol, and the washed precipitate is dispersed in the ultrapure water solution to prepare a spherical gold nanoparticle solution.

[0018] Furthermore, in the fifth step, the volume ratio of the mixed solution of water and ethylene glycol is H2O:EG=1:5.

[0019] An AuPt@NP5 / BiOI-MoS2 composite photoelectric material prepared by any of the above preparation methods.

[0020] This application also discloses an application of AuPt@NP5 / BiOI-MoS2 composite photoelectric material in a novel signal on-off type photoelectrochemical PEC biosensor system.

[0021] Furthermore, in a surface area of ​​0.07 cm 2 10 μL of AuPt@NP5 / BiOI-MoS2 composite photoelectric material was drop-coated on the glassy carbon electrode GCE to prepare the AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode.

[0022] Furthermore, the new signal switch-type photoelectrochemical (PEC) biosensor system uses a traditional three-electrode system, with AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode as the working electrode, platinum mesh as the counter electrode, and saturated calomel electrode (SCE) as the reference electrode. A xenon lamp is used to simulate visible light to illuminate the surface of the AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode, and the shading interval time is controlled as an adjustable "on-off" state. Photoelectrochemical detection is then performed using an electrochemical workstation in a solution containing ascorbic acid.

[0023] The working principle of the AuPt@NP5 / BiOI-MoS2 composite photoelectric material is as follows: Under visible light irradiation, AuPt nanoparticles are excited to generate electrons and holes. The conduction band of MoS2 can accept electrons from AuPt. Due to the energy level matching between BiOI and MoS2, the electrons are transferred to BiOI and ultimately reach the electrode, completing the electron transfer. The excellent conductivity of the AuPt bimetallic, the host-guest complexation between NP5 and AA, the combination of MoS2 and BiOI, the high mobility of MoS2, and the moderate band gap of BiOI help improve the separation efficiency of photogenerated electrons and holes and reduce the probability of recombination. These materials work synergistically to achieve excellent detection performance for carcinoembryonic antigen. This solution provides a novel and effective solution for the clinical detection of CEA and has broad application prospects.

[0024] Beneficial effects: This application provides an AuPt@NP5 / BiOI-MoS2 composite photoelectric material and its preparation method and application, which have the following beneficial effects compared with the existing technology:

[0025] 1. This application designs AuPt nanoparticles with bimetallic nanoparticles, which have host-guest complexation ability NP5 and BiOI-MoS2, and excellent photoelectrochemical performance and staggered band gap structure, which can promote carrier separation and are used for photoelectrochemical detection of carcinoembryonic antigen;

[0026] 2. Solve technical problems of existing detection technologies such as low sensitivity, limited detection range, expensive instruments, low efficiency, and difficult operation;

[0027] 3. The detection range of this application is 0.001 ng / mL to 50 ng / mL, and the minimum detection limit is 0.33 pg / mL (S / N=3);

[0028] 4. The pillararenes synthesized in this application have a good host-guest complex constant with AA of 36257;

[0029] 5. The CEA assay used in this application has good reproducibility, with a relative standard deviation of 1.9% for five parallel experiments.

[0030] Description of the drawings: Figure 1 : are transmission electron micrographs of the present application, wherein A and G are transmission electron micrographs of Au NPs, B and E are scanning electron micrographs of BiOI, C and F are scanning electron micrographs of BiOI-MoS2, D and H are transmission electron micrographs of AuPt NPs, and I is a scanning electron micrograph of AuPt@NP5 / BiOI-MoS2;

[0031] Figure 2The UV-visible absorption spectra and Fourier infrared spectra of the present application are shown in Figure 1, where A is the UV-visible absorption spectra of AuPt, NP5, BiOI-MoS2, and AuPt@NP5 / BiOI-MoS2, and B is the Fourier infrared spectra of NP5, AuPt@NP5, BiOI-MoS2, and AuPt@NP5 / BiOI-MoS2;

[0032] Figure 3 Figure 1 is a graph showing the CV curves and impedance curves of the present application, wherein A is the CV curves of AuPt@NP5, BiOI, BiOI-MoS2 and AuPt@NP5 / BiOI-MoS2 in 5 mM K3[Fe(CN)6] / K4[Fe(CN)6] and 0.1 M KCl, and B is the impedance curve; C is the CV curves of (a) GCE, (b) AuPt@NP5 / BiOI-MoS2 / GCE, (c) Ab / AuPt@NP5 / BiOI-MoS2 / GCE, (d) BSA / Ab / AuPt@NP5 / BiOI-MoS2 / GCE and (e) CEA / BSA / Ab / AuPt@NP5 / BiOI-MoS2 / GCE in 1 mM K3[Fe(CN)6] / K4[Fe(CN)6] and 0.1 M KCl, and D is the impedance curve;

[0033] Figure 4 It is the it curve and linear calibration curve of the present application, where A is the it curve of the biosensor for different concentrations of CEA, and B is the linear calibration curve. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and equivalent changes or modifications also fall within the scope defined by the claims of the present application.

[0035] Example 1: A method for preparing an AuPt@NP5 / BiOI-MoS2 composite photoelectric material, comprising: modifying molybdenum disulfide on bismuth oxyiodide by an in situ growth method to form a BiOI-MoS2 heterojunction; then functionalizing NP5 into bimetallic nanoparticles AuPt@NP5, which are distributed on the BiOI-MoS2 heterojunction, to prepare an AuPt@NP5 / BiOI-MoS2 composite photoelectric material, specifically comprising the following steps:

[0036] The first step is to prepare NP5 with a double amino column [5] aromatic hydrocarbon: ;

[0037] The second step is to prepare Au nanoparticles: using chloroauric acid as the raw material, citric acid and sodium citrate as reducing agents, a spherical gold nanoparticle solution is prepared by a thermal reduction method. The amount ratio of the chloroauric acid, citric acid and sodium citrate is 1 mL of 25.4 mM chloroauric acid: 0.9 mL of 0.1 M citric acid: 2.1 mL of 0.1 M sodium citrate;

[0038] Step 3: Synthesis of AuPt NPs by seed growth method: 200 μL of synthesized Au NPs were diluted in 800 μL of ultrapure water containing 20 wt% polyvinylpyrrolidone (PVP), and then kept at 37 ° C for 5 min to stabilize the Au NPs solution. 40 μL of L-ascorbic acid (100 mg / mL) and 40 μL of chloroplatinic acid were mixed with the Au NPs solution and immediately heated at 65 ° C and stirred at 600 rpm for 1 h until the color of the solution changed from red to brown and then to black, indicating that Pt was successfully deposited. Centrifuge at 1000 rpm for 15 min and wash three times with ultrapure water to remove excess reagents to obtain spherical amber nanoparticle solution AuPt NPs;

[0039] Step 4: Disperse 2 mg of NP5 in 1 mL of spherical amber nanoparticle solution AuPt NPs by ultrasonic method according to the dosage ratio, and ultrasonicate for 30 min to synthesize AuPt@NP5 composite photoelectric material;

[0040] In the fifth step, flower-like BiOI was prepared by a one-pot hydrothermal method: 0.485 g Bi(NO3)3·5H2O was first dissolved in 30 mL of a mixed solution of water and ethylene glycol (volume ratio H2O:EG=1:5) according to the mass volume ratio, and ultrasonicated for 5 min to obtain a transparent solution; then, 0.166 g polyvinylpyrrolidone (PVP) was added and stirred for 30 min; then 0.119 g potassium bromide (KBr) was added and stirred for 30 min; then, the mixture was heated in an autoclave at 160°C for 180 min, and the product was centrifuged three times at 6000 rpm for 5 min with ethanol and ultrapure water respectively; finally, the centrifuged sample was freeze-dried, and the orange-red powder of BiOI, namely flower-like BiOI, was collected for further use;

[0041] Step 6: Prepare a BiOI-MoS2 heterojunction by in situ growth: 0.05 g of sodium molybdate was dissolved in 60 mL of ultrapure water, followed by the addition of 0.0375 g of thioacetamide. The mixture was stirred vigorously for 1 hour to ensure homogeneity. 0.09 g of BiOI was added to the vigorously stirred solution and stirred for another 4 hours. The solution was then heated in an autoclave at 180°C for 24 hours. The product was centrifuged three times at 8000 rpm for 5 minutes using ultrapure water. Finally, the sample was freeze-dried to obtain a BiOI-MoS2 heterojunction.

[0042] Step 7: AuPt@NP5 / BiOI-MoS2 was synthesized by physical adsorption method: 2 mL of AuPt@NP5 composite photoelectric material prepared in the fourth step was dropped into 1.5 mg of BiOI-MoS2 heterojunction prepared in the sixth step, and stirred at 600 rpm for 5 min to obtain AuPt@NP5 / BiOI-MoS2 heterojunction, i.e., AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

[0043] Example 2: On a surface area of ​​0.07 cm 2 An AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode was prepared by drop-coating 10 μL of AuPt@NP5 / BiOI-MoS2 composite photoelectric material onto a glassy carbon electrode (GCE). The AuPt@NP5 / BiOI-MoS2 composite photoelectric material was used for photoelectrochemical detection of carcinoembryonic antigen. The AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode was placed in a solution containing AA for photoelectrochemical detection. All experiments used a conventional three-electrode system, with the AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode as the working electrode, a platinum mesh as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. A xenon lamp was used to simulate visible light illumination on the AuPt@NP5 / BiOI-MoS2 / GCE electrode surface, with the light shielding interval controlled as a controllable "on-off" mode. Photoelectrochemical detection was then performed using an electrochemical workstation.

[0044] Performance testing: 1. Morphology determination of Au NPs, AuPt NPs, BiOI, BiOI-MoS2, and AuPt@NP5 / BiOI-MoS2 composite optoelectronic materials: Figure 1 A is Au NPs with a smooth surface and a size of about 20 nm. Pt NPs were deposited on its surface using a seed-mediated growth method, as shown in Figure 5. Figure 1 As shown in Figure D, Pt NPs of approximately 4 nm are uniformly deposited on the surface of the gold nanoparticles, forming AuPt NPs. High-resolution transmission electron microscopy analysis of the Au NPs and AuPt NPs was performed. Figure 1Middle G clearly shows the gold lattice fringes, reflecting the face-centered cubic structure of the gold core, with a lattice spacing of approximately 0.236 nm, corresponding to the (111) plane of Au. Figure 1 The H-platinum shell also exhibits a face-centered cubic structure with a lattice spacing of 0.225 nm, corresponding to the (111) plane of Pt. Figure 1 Figures B and D in Figure 1 show the morphology of the prepared BiOI. The BiOI nanosheets are evenly distributed, present a clear sheet structure, have a smooth surface, no obvious cracks, and are approximately 2 μm in size. Figure 1 As shown in Figures C and F in Figure 1, thinner MoS2 nanosheets are uniformly adhered to the BiOI nanosheets to form a layered structure. Figure 1 As shown in Figure 1, AuPt NPs are distributed on the layered structure of BiOI-MoS2 and are tightly integrated with the underlying BiOI-MoS2 nanosheets.

[0045] 2. UV-visible absorption spectra and FTIR spectra of NP5, AuPt@NP5, BiOI-MoS2 and AuPt@NP5 / BiOI-MoS2: Figure 2 As shown in Figure A, BiOI-MoS2 has obvious absorption at 310 nm and 360 nm, corresponding to MoS2 and BiOI, respectively. Due to the surface plasmon resonance effect of Au, the corresponding ultraviolet absorption peak is observed at 527 nm. After the Au surface is modified with Pt, since platinum has no characteristic absorption peak in the ultraviolet spectrum, changes occur around gold, resulting in the disappearance of the absorption peak at 527 nm. NP5 has an ultraviolet absorption peak at 266 nm. The final composite material also shows the presence of this peak, confirming the successful preparation of AuPt@NP5 / BiOI-MoS2. As shown Figure 2 As shown in B, 596 cm in BiOI-MoS2 -1 The absorption peak at 517 cm corresponds to the Mo-S bond in MoS2, while the absorption peak at 517 cm -1 The absorption peak at 1645 cm corresponds to the Bi-O bond in BiOI. -1 The broad peak at 1059 cm is caused by the HOH bending vibration of water molecules. -1 and 1210 cm -1 The infrared absorption bands at 1420 cm -1 The peaks at correspond to the CH bending vibration. When BiOI-MoS2 is combined with AuPt@NP5, these peaks hardly change, which may be because the interaction between BiOI-MoS2 and AuPt@NP5 is physical adsorption without forming new chemical bonds.

[0046] 3. Photoelectrochemical characterization: As shown in Figure 3A, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were measured in 5.0 mM K3[Fe(CN)6] / K4[Fe(CN)6] and 0.1 M KCl solutions. Figure 3 As shown in Figure A, the oxidation current of AuPt@NP5 is the smallest because NP5 is an organic compound with poor redox properties. When MoS2 is composited with BiOI, the photocurrent is higher than that of BiOI alone. This may be due to the formation of a heterojunction between MoS2 and BiOI, which improves the efficiency of the electrochemical reaction and thus produces a higher current. The synergistic effect of the components in AuPt@NP5, BiOI and MoS2 makes the composite material AuPt@NP5 / BiOI-MoS2 show the highest current response. Figure 3 In curve B, the Rct values ​​for AuPt@NP5, BiOI, BiOI-MoS2, and AuPt@NP5 / BiOI-MoS2 were calculated to be 2061 Ω, 1592 Ω, 1356 Ω, and 986 Ω, respectively. This indicates that AuPt@NP5 / BiOI-MoS2 has the fastest charge transfer rate, consistent with the CV results. After Ab modification on AuPt@NP5 / BiOI-MoS2 / GCE (curve b), the current decreases and the impedance increases, indicating successful Ab immobilization on the electrode. To block the remaining active sites on the Ab / AuPt@NP5 / BiOI-MoS2 / GCE, the electrode was modified with BSA, further increasing the impedance. This is because bovine serum albumin is a poorly conductive protein. Finally, when CEA is modified on BSA / Ab / AuPt@NP5 / BiOI-MoS2 / GCE, the Rct value reaches its maximum, confirming the successful fabrication of the immunosensor.

[0047] 4. Photoelectrochemical detection of CEA: Figure 4 As shown in Figure A, the photocurrent response of CEA was tested in a PBS solution containing AA. It was found that as the CEA concentration increased from 0.001 ng / mL to 50 ng / mL, the photocurrent response gradually decreased. Figure 4 As shown in Figure B, the photocurrent response shows a good linear relationship with the logarithm of the CEA concentration. The standard regression equation is I = -0.0485 lg(CCEA) + 0.2285, R 2 = 0.9929. The calculated detection limit was 0.33 pg / mL (S / N=3), which was lower than that of other detection methods, indicating that the AuPt@NP5 / BiOI-MoS2 photoelectrochemical sensor has superior analytical performance.

[0048] Example 3: A method for preparing an AuPt@NP5 / BiOI-MoS2 composite photoelectric material, comprising: modifying molybdenum disulfide on bismuth oxyiodide by an in situ growth method to form a BiOI-MoS2 heterojunction; then functionalizing NP5 into bimetallic nanoparticles AuPt@NP5, which are distributed on the BiOI-MoS2 heterojunction, to prepare an AuPt@NP5 / BiOI-MoS2 composite photoelectric material, specifically comprising the following steps:

[0049] The first step is to prepare NP5 with a double amino column [5] aromatic hydrocarbon: ;

[0050] The second step is to prepare Au nanoparticles: using chloroauric acid as the raw material, citric acid and sodium citrate as reducing agents, a spherical gold nanoparticle solution is prepared by a thermal reduction method. The amount ratio of the chloroauric acid, citric acid and sodium citrate is 1.3 mL of 25.4 mM chloroauric acid: 1.2 mL of 0.1 M citric acid: 2.8 mL of 0.1 M sodium citrate;

[0051] Step 3: Synthesis of AuPt NPs by seed growth method: 400 μL of synthesized Au NPs were diluted in 1600 μL of ultrapure water containing 20 wt% polyvinylpyrrolidone (PVP), and then kept at 40 ° C for 10 min to stabilize the Au NPs solution. 80 μL of L-ascorbic acid (100 mg / mL) and 80 μL of chloroplatinic acid were mixed with the Au NPs solution and immediately heated at 70 ° C and stirred at 800 rpm for 1.2 h until the color of the solution changed from red to brown and then to black, indicating that Pt was successfully deposited. Centrifuge at 1200 rpm for 20 min and wash three times with ultrapure water to remove excess reagents to obtain spherical amber nanoparticle solution AuPt NPs;

[0052] Step 4: 2.5 mg of NP5 was dispersed in 1.2 mL of spherical amber nanoparticle solution AuPt NPs by ultrasonic method according to the dosage ratio, and ultrasonicated for 35 min to synthesize AuPt@NP5 composite photoelectric material;

[0053] In the fifth step, flower-like BiOI was prepared by a one-pot hydrothermal method: 0.97 g Bi(NO3)3·5H2O was first dissolved in 60 mL of a mixed solution of water and ethylene glycol (volume ratio H2O:EG=1:5) according to the mass volume ratio, and ultrasonicated for 10 min to obtain a transparent solution; then, 0.166~0.332 g polyvinylpyrrolidone (PVP) was added and stirred for 35 min; then 0.238 g potassium bromide (KBr) was added and stirred for 35 min; then, the solution was heated in an autoclave at 180°C for 200 min, and the product was centrifuged at 8000 rpm for 10 min three times with ethanol and ultrapure water; finally, the sample was freeze-dried, and the orange-red powder of BiOI, namely flower-like BiOI, was collected for further use;

[0054] Step 6: Prepare a BiOI-MoS2 heterojunction by in situ growth: 0.2 g of sodium molybdate was dissolved in 80 mL of ultrapure water, followed by the addition of 0.15 g of thioacetamide. The mixture was stirred vigorously for 1.2 h to ensure homogeneity. 0.36 g of BiOI was added to the vigorously stirred solution and stirred for another 4.2 h. The solution was then heated in an autoclave at 200°C for 26 h. The product was centrifuged three times at 10,000 rpm for 10 min using ultrapure water. Finally, the sample was freeze-dried to obtain a BiOI-MoS2 heterojunction.

[0055] Step 7: AuPt@NP5 / BiOI-MoS2 was synthesized by physical adsorption method: 2.5 mL of AuPt@NP5 composite photoelectric material prepared in the fourth step was dropped into 2 mg of BiOI-MoS2 heterojunction prepared in the sixth step, and stirred at 800 rpm for 10 min to obtain AuPt@NP5 / BiOI-MoS2 heterojunction, namely AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

[0056] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing AuPt@NP5 / BiOI-MOS2 composite photoelectric material, characterized by: Molybdenum disulfide is modified on bismuth iodide by an in situ growth method to form a BiOI-MoS2 heterojunction, and then NP5 is functionalized into bimetallic nanoparticles AuPt@NP5, which are distributed on the BiOI-MoS2 heterojunction to prepare AuPt@NP5 / BiOI-MoS2 composite photoelectric material, which specifically includes the following steps: The first step is to prepare NP5 with a double amino column [5] aromatic hydrocarbon: ； The second step is to prepare Au NPs: using chloroauric acid as the raw material and citric acid and sodium citrate as reducing agents, a spherical gold nanoparticle solution is prepared by a thermal reduction method. The amount ratio of chloroauric acid, citric acid and sodium citrate is 1-1.3 mL of 25.4 mM chloroauric acid: 0.9-1.2 mL of 0.1 M citric acid: 2.1-2.8 mL of 0.1 M sodium citrate; Step 3: Synthesis of AuPt NPs by seed growth method: 200-400 μL of Au NPs were diluted in 800-1600 μL of ultrapure water containing 20 wt% polyvinylpyrrolidone (PVP) by volume, and then maintained at 37°C-40°C for 5-10 min to stabilize the Au NPs solution; 40-80 μL of 100 mg / mL L-ascorbic acid and 40-80 μL of chloroplatinic acid were mixed with the Au NPs solution and immediately heated at 65-70°C and stirred at 600-800 rpm for 1-1.2 h, until the color of the solution changed from red to brown and then to black, indicating successful Pt deposition; centrifuged at 1000-1200 rpm for 15-20 min, and washed three times with ultrapure water to remove excess reagents to obtain spherical amber nanoparticle solution AuPt NPs; Step 4: Disperse 2 to 2.5 mg of NP5 in 1 to 1.2 mL of spherical amber nanoparticle solution (AuPt NPs) by ultrasonication according to the mass-to-volume ratio for 30 to 35 minutes to synthesize AuPt@NP5 composite photoelectric materials. In the fifth step, flower-like BiOI was prepared by a one-pot hydrothermal method: 0.485-0.97 g Bi(NO₃)₃·5H₂O was first dissolved in 30-60 mL of a mixed solution of water and ethylene glycol according to the mass-to-volume ratio and ultrasonicated for 5-10 min to obtain a transparent solution. Subsequently, 0.166-0.332 g polyvinylpyrrolidone (PVP) was added and stirred for 30-35 min. Then, 0.119-0.238 g potassium bromide (KBr) was added and stirred for 30-35 min. The mixture was then heated in an autoclave at 160-180°C for 180-200 min. The product was centrifuged three times at 6000-8000 rpm for 5-10 min in ethanol and ultrapure water, respectively. Finally, the centrifuged sample was freeze-dried and the orange-red powder of BiOI, i.e., flower-like BiOI, was collected for further use. Step 6: Prepare a BiOI-MoS2 heterojunction by in situ growth: dissolve 0.05-0.2 g of sodium molybdate in 60-80 mL of ultrapure water according to the mass-to-volume ratio, then add 0.0375-0.15 g of thioacetamide, and vigorously stir the mixture for 1-1.2 h to ensure homogeneity; add 0.09-0.36 g of BiOI to the vigorously stirred solution, continue stirring for 4-4.2 h, and then heat it in an autoclave at 180-200°C for 24-26 h. Centrifuge the product three times at 8000-10000 rpm for 5-10 min with ultrapure water; finally, freeze-dry the sample to obtain a BiOI-MoS2 heterojunction; Step 7: AuPt@NP5 / BiOI-MoS2 was synthesized by physical adsorption method: 2~2.5 mL of AuPt@NP5 composite photoelectric material prepared in the fourth step was dropwise added into 1.5~2 mg of BiOI-MoS2 heterojunction prepared in the sixth step according to the mass-to-volume ratio, and stirred at 600~800 rpm for 5~10 min to obtain AuPt@NP5 / BiOI-MoS2 heterojunction, i.e., AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

2. The method for preparing a AuPt@NP5 / BiOI-MoS2 composite photoelectric material according to claim 1, characterized in that: The specific steps of preparing the spherical gold nanoparticle solution by the thermal reduction method in the second step are as follows: adding 0.9 to 1.2 mL of 0.1 M citric acid and 2.1 to 2.8 mL of 0.1 M sodium citrate to 150 to 200 mL of boiling water, stirring at 500 to 700 rpm for 15 to 20 minutes; then adding 1 to 1.3 mL of 25.4 mM chloroauric acid, stirring at 500 to 700 rpm for 3 to 5 minutes, and then cooling in ice water. The obtained precipitate is washed with ultrapure water and ethanol, and the washed precipitate is dispersed in the ultrapure water solution to prepare the spherical gold nanoparticle solution.

3. The method for preparing a AuPt@NP5 / BiOI-MoS2 composite photoelectric material according to claim 1, characterized in that: In the fifth step, the volume ratio of water and ethylene glycol in the mixed solution is H2O:EG=1:

5.

4. An AuPt@NP5 / BiOI-MoS2 composite photoelectric material prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the AuPt@NP5 / BiOI-MoS2 composite photoelectric material according to claim 4 in a novel signal on-off photoelectrochemical (PEC) biosensor system.

6. Use of the AuPt@NP5 / BiOI-MoS2 composite photoelectric material according to claim 4 in a novel signal on-off type photoelectrochemical (PEC) biosensor system; Use of the AuPt@NP5 / BiOI-MoS2 composite photoelectric material according to claim 5 in a novel signal on-off type photoelectrochemical (PEC) biosensor system, characterized in that: On a surface area of ​​0.07 cm 2 10 μL of AuPt@NP5 / BiOI-MoS2 composite photoelectric material was drop-coated on the glassy carbon electrode GCE to prepare the AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode.

7. The use of the AuPt@NP5 / BiOI-MoS2 composite photoelectric material in a novel signal on-off type photoelectrochemical (PEC) biosensor system according to claim 6, characterized in that: The novel signal-switch photoelectrochemical (PEC) biosensor system uses a traditional three-electrode system with an AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode as the working electrode, a platinum mesh as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. A xenon lamp is used to simulate visible light to illuminate the surface of the AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode. Controlling the light-shielding interval acts as a controllable "on-off" switch. Photoelectrochemical detection is then performed using an electrochemical workstation in a solution containing ascorbic acid.

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