Au-coated NP5 / BiOI-MoS2 composite photoelectric material as well as preparation method and application thereof

Abstract

The invention discloses an Au (at) NP5 / BiOI-MoS2 composite photoelectric material and a preparation method and application thereof.The Au (at) NP5 / BiOI-MoS2 composite photoelectric material is modified with Pt, the surface of AuPtNPs is coated with a layer of diamino column [5] arene, AuPt (at) NP5 serves as a photoactive material, and a novel signal on-off type photoelectrochemical PEC biosensing system is designed and used for detecting carcino-embryonic antigens; the excellent conductivity of AuPt bimetal is utilized; the host-guest complexation between pillar [5] arene NP5 and an AA electron donor; the high mobility of MoS2 and the moderate band gap of BiOI help to improve the separation efficiency of photo-induced electrons and holes and reduce the recombination probability, and based on the multiple signal amplification capabilities of AuPt-coated NP5 / BiOI-MoS2, the electrode shows an excellent linear range when detecting carcino-embryonic antigens.

Description

Technical Field

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

[0002] Carcinoembryonic antigen (CEA) is a glycoprotein 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 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, accurate determination of 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 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 [5] aromatics, 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 play an important role in scientific research and practical applications due to their unique physical and chemical properties, good biocompatibility and easy modification. Gold (Au) and platinum (Pt) are both metal nanomaterials with excellent conductivity. Their surfaces are easy to chemically modify and can be combined with various biomolecules or chemical probes to improve the selectivity and specificity of sensors. Compared with 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 improve the photoelectrochemical activity.

[0005] BiOI (band gap of about 1.8 eV) has a layered structure, each layer is composed of Bi and I units, and Bi and I atoms are arranged alternately to form a two-dimensional plane connected by O atoms. The electronic structure of bismuth plays an important role in reducing the band gap and enhancing visible light absorption. However, the high photoelectric charge recombination rate limits its application in the field of photoelectric sensing. To solve this problem, researchers have carried out a lot of material modification work, including element doping, heterostructure construction and surface modification methods to improve the light absorption efficiency and promote the effective separation and transport of photogenerated electron-hole pairs. Among many transition metals, molybdenum disulfide (MoS2) has a unique layered structure and excellent physical and chemical properties. It is composed of three atomic layers of S-Mo-S stacked, and the layers interact through van der Waals forces and are bound by strong covalent bonds. This layered structure gives MoS2 excellent light absorption and photoelectric conversion capabilities. The multilayer MoS2 has a band gap of about 1.2 eV, and combined with BiOI to form a cross-bandgap 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, which 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 optoelectronic 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 issues solved:

[0008] The present application aims at the deficiencies of the prior art and solves the technical problems of low sensitivity, limited detection range, expensive instruments, need for specialized operators, low efficiency, slow speed, and difficult operation of the original detection technology, and provides an Au@NP5 / BiOI-MoS2 composite optoelectronic material and its preparation method and application.

[0009] Technical solution:

[0010] To achieve the above objectives, this application is implemented through the following technical solutions:

[0011] A method for preparing an Au@NP5 / BiOI-MoS2 composite photoelectric material comprises modifying molybdenum disulfide on bismuth iodide by an in-situ growth method to form a BiOI-MoS2 heterojunction, and then functionalizing NP5 into bimetallic nanoparticles AuPt@NP5, distributing the nanoparticles on the BiOI-MoS2 heterojunction, and preparing the AuPt@NP5 / BiOI-MoS2 composite photoelectric material, which specifically comprises the following steps:

[0012] In the first step, the aromatic NP5 with a double amino column [5] was prepared;

[0013] The second step is to prepare AuNPs: chloroauric acid is used as a raw material, citric acid and sodium citrate are used as reducing agents, and 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

[0014] ~1.2mL of 0.1M citric acid: 2.1~2.8mL of 0.1M sodium citrate;

[0015] Step 3: Synthesize AuPtNPs by seed growth method: dilute 200-400 μL of AuNPs in 800-1600 μL of ultrapure water containing 20 wt% polyvinylpyrrolidone PVP by volume ratio, and then keep at 37°C-40°C for 5-10 min to stabilize the AuNPs solution; mix 40-80 μL of 100 mg / mL L-ascorbic acid and 40-80 μL of chloroplatinic acid with the AuNPs solution, and immediately heat at 65-70°C and stir at 600-800 rpm for 1-1.2 h, until the color of the solution changes from red to brown and then to black, indicating that Pt is successfully deposited; centrifuge at 1000-1200 rpm for 15-20 min, and wash three times with ultrapure water to remove excess reagents to obtain spherical amber nanoparticle solution AuPtNPs;

[0016] Step 4: Disperse 2-2.5 mg NP5 in 1-1.2 mL spherical amber nanoparticle solution AuPtNPs according to the mass volume ratio by ultrasonic method, ultrasonicate for 30-35 min, and synthesize AuPt@NP5 composite photoelectric material;

[0017] 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 volume ratio, and ultrasonicated for 5-10 min to obtain a transparent solution; then, 0.166

[0018] ~0.332g polyvinyl pyrrolidone PVP, stir for 30~35min; then add 0.119~0.238g potassium bromide KBr, stir for 30

[0019] ~35min; then heated in an autoclave at 160~180℃ for 180~200min, the product was centrifuged three times at 6000~8000rpm for 5~10min with ethanol and ultrapure water respectively; finally, the centrifuged sample was freeze-dried, and the BiOI orange-red powder, i.e., flower-like BiOI, was collected for further use;

[0020] Step 6: Prepare BiOI-MoS2 heterojunction by in-situ growth method: Dissolve 0.05-0.2g sodium molybdate in 60

[0021] ~80mL of ultrapure water, then add 0.0375~0.15g of thioacetamide, and stir the mixture vigorously for 1~1.2h to ensure uniformity; add 0.09~0.36g of BiOI to the vigorously stirred solution, continue stirring for 4~4.2h, and then heat in an autoclave at 180~200℃ for 24~26h, and centrifuge the product three times at 8000~10000rpm for 5~10min with ultrapure water; finally, freeze-dry the sample to obtain a BiOI-MoS2 heterojunction;

[0022] 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 dropped 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.

[0023] Furthermore, the specific steps of preparing the spherical gold nanoparticle solution by the thermal reduction method in the second step are: adding 0.9-1.2 mL of 0.1 M citric acid: 2.1-2.8 mL of 0.1 M sodium citrate into 150-200 mL of boiling water, and stirring at 500-700 rpm for 15-20 min; then adding 1-1.3 mL of 25.4 mM chloroauric acid, stirring at 500-700 rpm for 3-5 min, and cooling in ice water, washing the obtained precipitate with ultrapure water and ethanol, and dispersing the washed precipitate into the ultrapure water solution to prepare the spherical gold nanoparticle solution.

[0024] Furthermore, in the fifth step, the volume ratio of water and ethylene glycol in the mixed solution is H2O:EG=1:5.

[0025] An Au@NP5 / BiOI-MoS2 composite photoelectric material prepared by any of the above preparation methods.

[0026] The present application also discloses an application of AuPt@NP5 / BiOI-MoS2 composite photoelectric material in a novel signal on-off type photoelectrochemical PEC biosensor system.

[0027] Furthermore, in a surface area of ​​0.07 cm 2 10μL AuPt@NP5 / BiOI-MoS2 composite photoelectric material was drop-coated on the glassy carbon electrode GCE to prepare AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode.

[0028] Furthermore, the novel 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, a platinum mesh as the counter electrode, and a saturated calomel electrode SCE as the reference electrode. A xenon lamp is used to simulate a visible light source 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". Then, an electrochemical workstation is used for photoelectrochemical detection in a solution containing ascorbic acid.

[0029] 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, and the conduction band of MoS2 can accept electrons from AuPt. Due to the energy level matching between BiOI and MoS2, electrons are transferred to BiOI and finally reach the electrode to complete the electron transfer; due to the excellent conductivity of 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 to improve the separation efficiency of photogenerated electrons and holes and reduce the probability of recombination; these materials work synergistically and have good detection performance for carcinoembryonic antigen. This scheme provides a novel and effective solution for clinical detection of CEA and has broad application prospects.

[0030] Beneficial effects:

[0031] The present application provides an Au@NP5 / BiOI-MoS2 composite photoelectric material and its preparation method and application, which have the following beneficial effects compared with the prior art:

[0032] 1. This application designs AuPt nanoparticles with bimetallic nanoparticles, which have excellent photoelectrochemical properties and staggered band gap structures of host-guest complexing ability NP5 and BiOI-MoS2, which can promote carrier separation and are used for photoelectrochemical detection of carcinoembryonic antigen;

[0033] 2. Solve the technical problems of the original detection technology, such as low sensitivity, limited detection range, expensive instruments, low efficiency, and difficult operation;

[0034] 3. The detection range of this application is 0.001ng / mL~50ng / mL, and the minimum detection limit is 0.33pg / mL (S / N=3);

[0035] 4. The pillar aromatics synthesized in this application have a good host-guest complex constant of 36257 with AA;

[0036] 5. The detection of CEA in this application has good reproducibility, and the relative standard deviation of 5 parallel experiments is 1.9%. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 are transmission electron microscope images of the present application, wherein A and G are transmission electron microscope images of AuNPs, B and E are scanning electron microscope images of BiOI, C and F are scanning electron microscope images of BiOI-MoS2, D and H are transmission electron microscope images of AuPtNPs, and I is a scanning electron microscope image of AuPt@NP5 / BiOI-MoS2;

[0038] Figure 2 It is the UV-visible absorption spectrum and Fourier infrared spectrum of the present application, wherein A is the UV-visible absorption spectrum of AuPt, NP5, BiOI-MoS2 and AuPt@NP5 / BiOI-MoS2, and B is the Fourier infrared spectrum of NP5, AuPt@NP5, BiOI-MoS2 and AuPt@NP5 / BiOI-MoS2;

[0039] Figure 3 : These are 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 5mM K3[Fe(CN)6] / K4[Fe(CN)6] and 0.1M 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 1mM K3[Fe(CN)6] / K4[Fe(CN)6] and 0.1M KCl, and D is the impedance curve;

[0040] Figure 4 It is the it curve and linear calibration curve of the present application, wherein A is the it curve of the biosensor for different concentrations of CEA, and B is the linear calibration curve;

[0041] Figure 5 This is the synthetic route of the bisamino column [5] aromatic hydrocarbon NP5 of the present application. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used 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 limited by the claims of the present application.

[0043] Embodiment 1:

[0044] A method for preparing an Au@NP5 / BiOI-MoS2 composite photoelectric material comprises the following steps: modifying molybdenum disulfide on bismuth iodide by an in-situ growth method to form a BiOI-MoS2 heterojunction, and then functionalizing NP5 into bimetallic nanoparticles AuPt@NP5, distributing the nanoparticles on the BiOI-MoS2 heterojunction, and preparing an AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

[0045] The first step, such as Figure 5 As shown, NP5 with a double amino pillar [5]arene was prepared;

[0046] The second step is to prepare Au nanoparticles: chloroauric acid is used as a raw material, citric acid and sodium citrate are used as reducing agents, and 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 mL of 25.4 mM chloroauric acid:

[0047] 0.9 mL of 0.1 M citric acid: 2.1 mL of 0.1 M sodium citrate;

[0048] Step 3: Synthesis of AuPt NPs by seed growth method: 200 μL of synthesized AuNPs 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 AuNPs solution. 40 μL of L-ascorbic acid (100 mg / mL) and 40 μL of chloroplatinic acid were mixed with the AuNPs 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;

[0049] Step 4: Disperse 2 mg NP5 in 1 mL spherical amber nanoparticle solution AuPtNPs according to the dosage ratio by ultrasonic method, ultrasonicate for 30 min, and synthesize AuPt@NP5 composite photoelectric material;

[0050] The fifth step is to prepare flower-like BiOI by a one-pot hydrothermal method: first, 0.485 g Bi(NO3)3·5H2O was 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 polyvinyl pyrrolidone PVP was added and stirred for 30 min; then 0.119 g potassium bromide KBr was added and stirred for 30 min; then, it was heated in an autoclave at 160°C for 180 min, and the product was centrifuged at 6000 rpm for 5 min three times with ethanol and ultrapure water respectively; finally, the centrifuged sample was freeze-dried, and the BiOI orange-red powder, i.e., flower-like BiOI, was collected for further use;

[0051] Step 6: Prepare BiOI-MoS2 heterojunction by in-situ growth method: Dissolve 0.05g sodium molybdate in 60mL ultrapure water, then add 0.0375g thioacetamide, and stir the mixture vigorously for 1h to ensure uniformity. Add 0.09g BiOI to the vigorously stirred solution, continue stirring for 4h, then heat in an autoclave at 180℃ for 24h, and centrifuge the product three times at 8000rpm for 5min with ultrapure water; finally, freeze-dry the sample to obtain BiOI-MoS2 heterojunction;

[0052] Step 7: AuPt@NP5 / BiOI-MoS2 was synthesized by physical adsorption method: 2mA AuPt@NP5 composite photoelectric material prepared in the fourth step was dropped into 1.5mg BiOI-MoS2 heterojunction prepared in the sixth step, and stirred at 600rpm for 5min to obtain AuPt@NP5 / BiOI-MoS2 heterojunction, i.e. AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

[0053] Embodiment 2:

[0054] The surface area is 0.07 cm 210μL AuPt@NP5 / BiOI-MoS2 composite photoelectric material was drop-coated on the glassy carbon electrode GCE to prepare AuPt@NP5 / BiOI-MoS2 / GCE nanocomposite electrode. An application of AuPt@NP5 / BiOI-MoS2 composite photoelectric material in photoelectric 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 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 was used to simulate visible light source to illuminate the surface of the AuPt@NP5 / BiOI-MoS2 / GCE electrode, and the shading interval time was controlled as an adjustable "on-off", and then the electrochemical workstation was used for photoelectrochemical detection.

[0055] Performance Testing

[0056] 1. Morphological determination of AuNPs, AuPtNPs, BiOI, BiOI-MoS2 and AuPt@NP5 / BiOI-MoS2 composite optoelectronic materials

[0057] Figure 1 A is AuNPs, which has a smooth surface and a size of about 20 nm. PtNPs are deposited on its surface using a seed-mediated growth method, such as Figure 1 As shown in Figure D, it can be observed that PtNPs of about 4 nm are uniformly deposited on the surface of gold nanoparticles to form AuPt NPs. High-resolution transmission electron microscopy analysis of AuNPs and AuPtNPs was performed. Figure 1 Middle 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 presents 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 about 2 μm in size. Figure 1 As shown in Figures C and F in Figure 1, the thinner MoS2 nanosheets are uniformly adhered to the BiOI nanosheets to form a layered structure. Figure 1 As shown in Figure 1. AuPtNPs are distributed on the layered structure of BiOI-MoS2 and are tightly integrated with the underlying BiOI-MoS2 nanosheets.

[0058] 2. UV-visible absorption spectra and Fourier transform infrared spectra of NP5, AuPt@NP5, BiOI-MoS2 and AuPt@NP5 / BiOI-MoS2

[0059] like Figure 2 As shown in Figure A, BiOI-MoS2 has obvious absorption at 310nm and 360nm, corresponding to MoS2 and BiOI, respectively. Due to the surface plasmon resonance effect of Au, the corresponding UV absorption peak is observed at 527nm. After Pt is modified on the Au surface, since platinum has no characteristic absorption peak in the UV spectrum, changes occur around gold, resulting in the disappearance of the absorption peak at 527nm. NP5 has an ultraviolet absorption peak at 266nm. The final composite material also shows the presence of this peak, confirming the successful preparation of AuPt@NP5 / BiOI-MoS2. Figure 2 As shown in B, 596 cm- -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 1645cm 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 1210cm -1 The infrared absorption bands at 1420cm -1 The peaks at correspond to CH bending vibrations. These peaks hardly change after BiOI-MoS2 is combined with AuPt@NP5, which may be because the interaction between BiOI-MoS2 and AuPt@NP5 is physical adsorption without forming new chemical bonds.

[0060] 3. Photoelectrochemical Characterization

[0061] like Figure 3 As shown in Figure A, the cyclic voltammetry (CV) and 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 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 3In curve b, the Rct values ​​of AuPt@NP5, BiOI, BiOI-MoS2 and AuPt@NP5 / BiOI-MoS2 can be calculated to be 2061Ω, 1592Ω, 1356Ω and 986Ω, respectively, indicating that the charge transfer rate of AuPt@NP5 / BiOI-MoS2 is the fastest, which is consistent with the CV results. After Ab is modified on AuPt@NP5 / BiOI-MoS2 / GCE (curve b), the current decreases and the impedance value increases, indicating that Ab has been successfully immobilized on the electrode. In order to block the residual active sites on Ab / AuPt@NP5 / BiOI-MoS2 / GCE, the electrode is modified with BSA to further increase the impedance value. This is because bovine serum albumin is a protein with poor conductivity. Finally, when CEA is modified on BSA / Ab / AuPt@NP5 / BiOI-MoS2 / GCE, the Rct value reaches the maximum value, proving that the immunosensor is successfully prepared.

[0062] 4. Photoelectrochemical detection of CEA

[0063] like Figure 4 As shown in Figure A, the photocurrent response of CEA concentration in PBS solution containing AA was tested, and 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 B, the photocurrent response has a good linear relationship with the logarithm of CEA concentration. The standard regression equation is I = -0.0485lg (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 had superior analytical performance.

[0064] Example 3

[0065] A method for preparing an AuPt@NP5 / BiOI-MoS2 composite photoelectric material comprises the following steps: modifying molybdenum disulfide on bismuth iodide by an in-situ growth method to form a BiOI-MoS2 heterojunction, and then functionalizing NP5 into bimetallic nanoparticles AuPt@NP5, distributing the nanoparticles on the BiOI-MoS2 heterojunction, and preparing an AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

[0066] The first step, such as Figure 5 As shown, NP5 with a double amino pillar [5]arene was prepared;

[0067] The second step is to prepare Au nanoparticles: chloroauric acid is used as a raw material, citric acid and sodium citrate are used as reducing agents, and 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:

[0068] 1.2 mL of 0.1 M citric acid: 2.8 mL of 0.1 M sodium citrate;

[0069] Step 3: Synthesis of AuPtNPs by seed growth method: 400 μL of synthesized AuNPs 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 AuNPs solution. 80 μL of L-ascorbic acid (100 mg / mL) and 80 μL of chloroplatinic acid were mixed with the AuNPs 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;

[0070] Step 4: Disperse 2.5 mg NP5 in 1.2 mL spherical amber nanoparticle solution AuPtNPs by ultrasonic method according to the dosage ratio, and ultrasonicate for 35 min to synthesize AuPt@NP5 composite photoelectric material;

[0071] 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

[0072] ~0.332g polyvinylpyrrolidone PVP, stirred for 35min; then added 0.238g potassium bromide KBr, stirred for 35min; then heated in an autoclave at 180°C for 200min, and the product was centrifuged three times at 8000rpm for 10min with ethanol and ultrapure water;

[0073] Finally, the sample was freeze-dried and the BiOI orange-red powder, i.e., flower-like BiOI, was collected for further use;

[0074] Step 6: Prepare BiOI-MoS2 heterojunction by in-situ growth method: Dissolve 0.2g sodium molybdate in 80mL ultrapure water, then add 0.15g thioacetamide, and stir the mixture vigorously for 1.2h to ensure uniformity. Add 0.36g BiOI to the vigorously stirred solution, continue stirring for 4.2h, then heat in an autoclave at 200℃ for 26h, centrifuge the product three times at 10000rpm for 10min with ultrapure water; finally, freeze-dry the sample to obtain BiOI-MoS2 heterojunction;

[0075] 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, i.e. AuPt@NP5 / BiOI-MoS2 composite photoelectric material.

[0076] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and 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 in that: 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: In the first step, the aromatic NP5 with a double amino column [5] was prepared; The second step is to prepare AuNPs: using chloroauric acid as a raw material, citric acid and sodium citrate as reducing agents, a spherical gold nanoparticle solution is prepared by a thermal reduction method, wherein 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: Synthesize AuPtNPs by seed growth method: dilute 200-400 μL of AuNPs in 800-1600 μL of ultrapure water containing 20 wt% polyvinylpyrrolidone PVP by volume ratio, and then keep at 37°C-40°C for 5-10 min to stabilize the Au NPs solution; mix 40-80 μL of 100 mg / mL L-ascorbic acid and 40-80 μL of chloroplatinic acid with the Au NPs solution, and immediately heat at 65-70°C and stir at 600-800 rpm for 1-1.2 h, until the color of the solution changes from red to brown and then to black, indicating that Pt is successfully deposited; centrifuge at 1000-1200 rpm for 15-20 min, and wash three times with ultrapure water to remove excess reagents to obtain spherical amber nanoparticle solution AuPtNPs; Step 4: Disperse 2-2.5 mg NP5 in 1-1.2 mL spherical amber nanoparticle solution AuPtNPs according to the mass volume ratio by ultrasonic method, ultrasonicate for 30-35 min, and synthesize AuPt@NP5 composite photoelectric material; The fifth step is to prepare flower-like BiOI by a one-pot hydrothermal method: first, 0.485-0.97 g Bi(NO3)3·5H2O is dissolved in 30-60 mL of a mixed solution of water and ethylene glycol according to the mass volume ratio, and ultrasonicated for 5-10 min to obtain a transparent solution; then, 0.166-0.332 g of polyvinyl pyrrolidone PVP is added and stirred for 30-35 min; then 0.119-0.238 g of potassium bromide KBr is added and stirred for 30-35 min; then, it is heated in an autoclave at 160-180°C for 180-200 min, and the product is centrifuged three times at 6000-8000 rpm for 5-10 min with ethanol and ultrapure water respectively; finally, the centrifuged sample is freeze-dried, and the BiOI orange-red powder, i.e., flower-like BiOI, is collected for further use; Step 6: Prepare BiOI-MoS2 heterojunction by in-situ growth method: dissolve 0.05-0.2g sodium molybdate in 60-80mL ultrapure water according to mass volume ratio, then add 0.0375-0.15g thioacetamide, and stir the mixture vigorously for 1-1.2h to ensure uniformity; add 0.09-0.36g BiOI to the vigorously stirred solution, continue stirring for 4-4.2h, and then heat in an autoclave at 180-200℃ for 24-26h, and centrifuge the product three times at 8000-10000rpm for 5-10min with ultrapure water; finally, freeze-dry the sample to obtain 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 dropped 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.

2. The method for preparing the 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: adding 0.9-1.2 mL of 0.1 M citric acid and 2.1-2.8 mL of 0.1 M sodium citrate into 150-200 mL of boiling water, and stirring at 500-700 rpm for 15-20 min; then adding 1-1.3 mL of 25.4 mM chloroauric acid, stirring at 500-700 rpm for 3-5 min, and cooling in ice water, washing the obtained precipitate with ultrapure water and ethanol, and dispersing the washed precipitate into the ultrapure water solution to prepare the spherical gold nanoparticle solution.

3. The method for preparing the 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. An application of the AuPt@NP5 / BiOI-MoS2 composite photoelectric material according to claim 4 in a novel signal on-off type photoelectrochemical (PEC) biosensor system.

6. 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 5, characterized in that: The surface area is 0.07 cm 2 10μL AuPt@NP5 / BiOI-MoS2 composite photoelectric material was drop-coated on the glassy carbon electrode GCE to prepare 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 type photoelectrochemical PEC biosensor system uses the 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 a visible light source 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". Then, an electrochemical workstation is used for photoelectrochemical detection in a solution containing ascorbic acid.

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