Preparation method and application of Au-TiO2 / MoS2 photoelectrochemical biosensor

Abstract

The invention provides a preparation method of an Au-TiO2 / MoS2 photoelectrochemical biosensor and an application of the Au-TiO2 / MoS2 photoelectrochemical biosensor. Comprising the following steps: step 1, preparing a TiO2 film; step 2, preparation of a TiO2 / MoS2 composite film; and step 3, preparation of the Au-TiO2 / MoS2 photoelectrochemical biosensor. The invention also relates to an application of the Au-TiO2 / MoS2 photoelectrochemical biosensor in the aspect of detecting a depression marker serotonin. According to the invention, a uniform TiO2 thin film is prepared through a slurry film coating technology, and the MoS2 nano layer and the TiO2 thin film are effectively combined to form a heterojunction, so that the electron utilization rate is improved, and effective binding sites of a DNA single-chain aptamer are provided at the same time; the ultrathin Au nano layer deposited through a high vacuum evaporation coating technology forms an effective carrier transport system, the photoelectrochemical performance is improved, the binding sites of a DNA single-stranded aptamer are further increased, and the sensitivity and specificity of the sensor are greatly improved. The method has application potential and wide expansion capability in the field of early screening of depression markers.

Description

Technical Field

[0001] The present invention belongs to the field of biosensor technology; in particular, it relates to an Au-TiO 2 / MoS 2 Preparation methods and applications of photoelectrochemical biosensors. Background Art

[0002] In recent years, depression has become a serious social problem. As a key depression marker, the neurotransmitter serotonin has great potential in depression screening. Currently, common serotonin detection technologies mainly include fluorescence, gas chromatography, electrochemical methods, etc. However, these methods have the following shortcomings: long test time, expensive equipment, etc. Compared with the above methods, photoelectrochemical biosensors have the great advantages of simple equipment, efficient testing, high sensitivity, and low cost.

[0003] TiO 2 As a classic semiconductor metal oxide, it has many advantages such as stable performance, high electron mobility, good biocompatibility, etc., and can be used as one of the advantageous materials for building biosensors. However, there are many interfering substances in the test environment related to serotonin, and the concentration to be tested is very low, which puts higher requirements on the detection specificity and sensitivity of biosensors. Therefore, being able to stably anchor the biological probe on the surface of the semiconductor photoelectrode is a very critical factor. Summary of the invention

[0004] The purpose of the present invention is to provide a Au-TiO 2 / MoS 2 Preparation methods and applications of photoelectrochemical biosensors.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention relates to an Au-TiO 2 / MoS 2 The preparation method of the photoelectrochemical biosensor comprises the following steps:

[0007] Step 1, TiO 2 Film preparation

[0008] (1.1) Add appropriate amount of TiO 2 Mix ethyl cellulose, glass powder and Span in a mixed solution of butyl carbitol and butyl carbitol acetate, stir evenly, and obtain TiO 2 Slurry precursor 1;

[0009] (1.2) TiO 2 The slurry precursor 1 is fully stirred to obtain TiO 2 Slurry precursor 2;

[0010] (1.3) TiO 2 The slurry precursor 2 was filtered and ball-milled to obtain TiO 2 Slurry;

[0011] (1.4) After cleaning the 12cm*12cm FTO, soak it in deionized water and 2 Blow clean;

[0012] (1.5) The sample was coated with TiO uniformly on a 12cm*12cm FTO film. 2 Film, dry;

[0013] (1.6) Annealed at 500℃ in a muffle furnace to obtain TiO 2 film;

[0014] Step 2, TiO 2 / MoS 2 Preparation of composite films

[0015] (2.1) Transfer 0.013 g of ammonium tetrathiomolybdate into 1 mL of N,N-dimethylformamide and sonicate for 30 minutes to obtain a homogeneous solution;

[0016] (2.2) TiO 2 The film is cut into pieces of 4cm*4cm in size and 2 Blow clean;

[0017] (2.3) Using spin coating technology, 400 μL of the solution was evenly spin-coated onto a 4 cm*4 cm TiO 2 On the film, let it stand and dry at room temperature;

[0018] (2.4) The sample was placed in a plasma enhanced chemical vapor deposition tube furnace, and the temperature was raised to 400°C at 10°C / min under low pressure and high purity Ar atmosphere for 1 hour, then washed with pure water and dried to obtain TiO 2 / MoS 2 Composite film;

[0019] Step 3, Au-TiO 2 / MoS 2 Preparation of photoelectrochemical biosensors

[0020] (3.1) High vacuum evaporation coating technology is used (in the evaporation chamber, the solid material placed on the tungsten boat is controlled by electric current to reach the melting point, and the temperature is further increased to the evaporation point. At this time, the material obtains enough energy to leave the surface and turn into vapor. The high vacuum prevents the vapor from reacting or scattering with other substances during the movement process, so that it reaches the substrate to condense and form a thin film;) 2 / MoS 2 The surface of the composite film is evaporated with Au metal film with a thickness of 0.2 nm, and the sample is cleaned;

[0021] (3.2) In a plasma enhanced chemical vapor deposition tube furnace, Au-TiO was annealed at 450 °C under low pressure and high purity Ar. 2 / MoS 2 Photoanode;

[0022] (3.3) Au-TiO 2 / MoS 2 The photoanode was cut into samples with a size of 1 cm*0.5 cm and 2 After cleaning, the aptamer probe was coated on the Au-TiO 2 / MoS 2 The surface of the photoanode is incubated and dried;

[0023] (3.4) Rinse the film surface with ultrapure water and dry it naturally to obtain Au-TiO 2 / MoS 2 Photoelectrochemical biosensors.

[0024] Preferably, in (1.1), the TiO 2 The mass ratio of butyl carbitol, butyl carbitol acetate and ethyl cellulose is 1:0.3:0.3125:0.0375; the volume ratio of butyl carbitol and butyl carbitol acetate in the mixed solution of butyl carbitol and butyl carbitol acetate is 1:1.

[0025] Preferably, in (1.2), the stirring is performed by an electronic stirrer at a speed of 800-1200 rpm for a stirring time of 12 to 36 hours.

[0026] Preferably, in (1.3), the ball milling is performed using a planetary ball mill with a rotation speed of 400 to 500 rpm, and the ball milling time is 5 to 10 hours.

[0027] Preferably, in (1.5), the TiO 2 The thickness of the film is 50-100 um, the speed of the scraping is 2-5 mm / s, the drying is carried out on a heating table, and the drying temperature is 60°C.

[0028] Preferably, in (2.3), the spin coating has a rotation speed of 1500 to 3000 rpm and a time of 30 to 60 s.

[0029] Preferably, in (2.4), the Ar flow rate in the plasma enhanced chemical vapor deposition tube furnace is 30 to 50 sccm, and the gas pressure in the chamber is 10 to 30 Pa.

[0030] Preferably, in (3.2), the Ar flow rate in the plasma enhanced chemical vapor deposition tube furnace is 30 to 50 sccm, and the gas pressure in the chamber is 10 to 30 Pa.

[0031] Preferably, in (3.3), the aptamer probe is a DNA aptamer probe of serotonin; the incubation temperature is 4° C., and the incubation time is 12 to 15 hours.

[0032] The principle of the method involved in the present invention is: first, prepare TiO 2 Thin film; Reuse MoS 2 Nanolayer and TiO 2 Thin film heterojunction effectively combined to prepare TiO 2 / MoS 2 The composite film improves the electron utilization rate and provides an effective binding site for the DNA single-stranded aptamer. Finally, the ultra-thin Au nanolayer deposited by high vacuum evaporation coating technology combines Au and TiO 2 / MoS 2 The composite formed an effective carrier transport system, improved the photoelectrochemical performance, further increased the binding sites of the DNA single-stranded aptamer, greatly improved the sensitivity and specificity of the sensor, and finally constructed the Au-TiO 2 / MoS 2 Photoelectrochemical biosensors.

[0033] The present invention also relates to the Au-TiO prepared according to claim 1 2 / MoS 2 Photoelectrochemical biosensor for the detection of serotonin.

[0034] The present invention has the following advantages:

[0035] (1) The method of the present invention efficiently converts MoS 2 Layer with TiO 2 Thin films are combined to form TiO 2 / MoS 2 Heterojunction effectively increases the light absorption range of the sensor, thereby improving the electron utilization rate; due to MoS 2 Layer with TiO 2 The van der Waals forces generated between them help to adsorb the aptamer of serotonin, thereby improving the sensitivity and specificity of semiconductor photoelectrochemistry.

[0036] (2) The method of the present invention is to fix the gold nanolayer by evaporation technology, which will be combined with TiO 2 / MoS 2 MoS on the composite film surface 2The Au-S bond is formed in the layer, thereby combining Au more firmly, which not only effectively improves the stability of the sensor, but also improves the carrier utilization efficiency, and finally enhances the photocurrent response of the sensor; in addition, the Au-TiO prepared by the present invention 2 / MoS 2 The nanogold layer on the surface of the photoelectric biosensor produces Au-S bonds with the serotonin aptamer, providing more binding sites for specific probes, thereby improving the sensitivity and accuracy of the sensor and broadening the linear detection area of ​​the sensor.

[0037] (3) Au-TiO prepared by the method of the present invention 2 / MoS 2 Photoelectric biosensor, effectively combining Au with TiO 2 / MoS 2 Heterojunction composite, MoS 2 The advantages of Au complement each other, effectively improving the performance of photoelectrochemical sensors, while also improving the sensitivity and specificity of semiconductor chemical sensors and broadening the linear detection area.

[0038] (4) Au-TiO prepared by the method of the present invention 2 / MoS 2 Photoelectric biosensors have the advantages of high sensitivity and excellent specificity, and have broad application potential and expansion capabilities in areas such as early screening of depression markers. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Au-TiO 2 / MoS 2 The linear curve of the photoelectrochemical biosensor for detecting serotonin;

[0040] Figure 2 Au-TiO 2 / MoS 2 Figure 2. Specificity evaluation of photoelectrochemical biosensor for serotonin. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments are only further descriptions of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0042] Example

[0043] This embodiment relates to an Au-TiO 2 / MoS 2 The preparation method of the photoelectrochemical biosensor comprises the following steps:

[0044] Step 1, TiO 2 Film preparation

[0045] ① 8g TiO 2 Powder, 2.4g ethyl cellulose, 2.5g glass powder, 0.3g Span, stir evenly with a stirring rod, add 15mL butyl carbitol and 15mL butyl carbitol acetate, continue stirring with a stirring rod to obtain TiO 2 Slurry precursor 1;

[0046] ②TiO 2 The slurry precursor 1 was moved to an electronic stirrer, with a rotation speed of 1000 rpm and constant temperature and humidity for 24 hours to obtain TiO 2 Slurry precursor 2;

[0047] ③TiO 2 The slurry precursor 2 was crushed and filtered once in a three-roll mill, and then ball-milled for 8 hours at a speed of 500 rpm using a planetary ball mill to obtain TiO 2 Slurry;

[0048] ④Take out a 12cm*12cm FTO sample, ultrasonically place it in a solution of FTO cleaning solution: pure water 1:9 for 10 to 20 minutes, then ultrasonically place it in anhydrous ethanol for 10 to 20 minutes, then ultrasonically place it in pure water for 10 to 20 minutes, take out the sample and ultrasonically place it in N 2 Blow clean;

[0049] ⑤ Move the sample onto the coating apparatus substrate, adjust the coating apparatus height to 100um, coating speed to 2mm / s, TiO 2 After the slurry is evenly applied on the sample, the film coating begins. After the film coating, the sample is placed on a 60°C constant temperature heating table to dry for 3.5 hours;

[0050] ⑥ Heat the dried sample in a muffle furnace at a rate of 10°C / min to 500°C and keep it at that temperature for 2 hours to obtain TiO 2 film;

[0051] Step 2, TiO 2 / MoS 2 Preparation of composite films

[0052] ① Dissolve 0.013 g of ammonium tetrathiomolybdate in 1 mL of N,N-dimethylformamide; ultrasonicate for 30 minutes to obtain a uniform solution;

[0053] ②TiO 2 The film is cut into pieces of 4cm*4cm in size and 2 Blow clean;

[0054] ③Use spin coating technology to evenly drop 400uL on a 4cm*4cm TiO2 On the film, the spin coater speed was 2000 rpm, the spin coating time was 50 s, and it was left to dry at room temperature;

[0055] ④ Place the sample in a plasma enhanced chemical vapor deposition tube furnace, control the flow of argon gas in the furnace, the flow rate is 30sccm, the gas pressure is maintained at 15Pa, and the temperature is raised to 400℃ at a rate of 10℃ / min, kept warm for 1 hour, washed with pure water, and dried to obtain TiO 2 / MoS 2 Composite film;

[0056] Step 3, Au-TiO 2 / MoS 2 Preparation of photoelectrochemical biosensors

[0057] ①Using high vacuum evaporation coating technology, on TiO 2 / MoS 2 The surface of the composite film is evaporated with Au metal film with a thickness of 0.2 nm, and the sample is cleaned;

[0058] ② Place the sample in a plasma enhanced chemical vapor deposition tube furnace, control the flow of argon gas in the furnace, the flow rate is 30sccm, the gas pressure is maintained at 15Pa, and the temperature is increased to 450℃ at a rate of 10℃ / min and kept for 1 hour to obtain Au-TiO 2 / MoS 2 Photoanode;

[0059] ③ Prepare 1uM serotonin aptamer probe and obtain Au-TiO 2 / MoS 2 The photoanode was cut into 1cm*0.5cm size and 2 After cleaning, the aptamer probe was coated with Au-TiO 2 / MoS 2 The surface of the photoanode was incubated in a 4°C refrigerator for 14 h;

[0060] ④ Rinse the film surface with ultrapure water and dry it naturally to obtain Au-TiO 2 / MoS 2 Photoelectrochemical biosensors.

[0061] Conduct performance tests on the products obtained during the preparation process

[0062] The tested solutions of different concentrations were applied on the prepared Au-TiO 2 / MoS 2The surface of the photoelectrochemical biosensor was incubated at a constant temperature for 20 minutes, and then the electrode surface was fully cleaned and dried. The Pt electrode was used as the working electrode, and the Ag / AgCl electrode was used as the reference electrode. The light intensity was 2 mW / cm 2 Under the irradiation of 365nm monochromatic light, the sensing detection characteristics of the series of sensors were tested by the time-current curve function of the electrochemical workstation.

[0063] Figure 1 Au-TiO 2 / MoS 2 The characteristic curve of the photoelectric chemical biosensor for the depression marker serotonin shows that the photocurrent signal decreases with the increase of serotonin concentration, which proves that the biosensor prepared by the method of the present invention can not only be used to detect the concentration of serotonin, but also has an inhibitory sensing performance. The detection line width is 10 -13 ~10 -9 ug / L, detection limit 6.8×10 -14 ug / L(S / N=3).

[0064] Figure 2 The Au-TiO prepared for testing 2 / MoS 2 The detection specificity of Au-TiO2 photoelectrochemical biosensor for serotonin 2 / MoS 2 The photoelectrochemical biosensor has a very obvious light response signal to serotonin (close to 3uA / cm 2 ), while the responses to other interference items (dopamine, glucose, bovine serum albumin, NaCl) were weak, much smaller than that of the Au-TiO 2 / MoS 2 The photoelectrochemical biosensor has a very obvious light response signal value to serotonin; therefore, the Au-TiO prepared by the method of the present invention 2 / MoS 2 After the serotonin aptamer was immobilized, the photoelectrochemical biosensor had a strong detection specificity for serotonin.

[0065] It can be seen that the present invention firstly prepares uniform TiO 2 Thin film, MoS 2 Nanolayer and TiO 2The heterojunction with effective film bonding improves the electron utilization rate and provides effective binding sites for single-stranded DNA aptamers. The ultra-thin Au nanolayer deposited by high-vacuum evaporation coating technology forms an effective carrier transport system, improves the photoelectrochemical performance, and further increases the binding sites for single-stranded DNA aptamers, greatly improving the sensitivity and specificity of the sensor.

[0066] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A method for preparing an Au-TiO2 / MoS2 photoelectrochemical biosensor, characterized in that: The following steps are involved: Step 1, Preparation of TiO2 thin film (1.1) Mix appropriate amounts of TiO2, ethyl cellulose, glass powder and Span in a mixed solution of butyl carbitol and butyl carbitol acetate, stir evenly, and obtain a TiO2 slurry precursor 1; (1.2) Fully stirring the TiO2 slurry precursor 1 to obtain the TiO2 slurry precursor 2; (1.3) filtering and ball-milling the TiO2 slurry precursor 2 to obtain a TiO2 slurry; (1.4) After cleaning the 12cm*12cm FTO, soak it in deionized water and blow it clean with N2; (1.5) Apply TiO2 film evenly on 12cm*12cm FTO and dry; (1.6) Annealing at 500°C in a muffle furnace to obtain TiO2 thin film; Step 2, preparation of TiO2 / MoS2 composite film (2.1) Transfer 0.013 g of ammonium tetrathiomolybdate into 1 mL of N,N-dimethylformamide and sonicate for 30 minutes to obtain a homogeneous solution; (2.2) Cut the TiO2 film into 4cm*4cm pieces and purge them with N2; (2.3) Spin-coat 400 μL of the solution evenly onto a 4 cm*4 cm TiO2 film and allow to dry at room temperature; (2.4) The sample was placed in a plasma enhanced chemical vapor deposition tube furnace, and the temperature was raised to 400°C at 10°C / min under a low pressure and high purity Ar atmosphere, and kept for 1 hour, and then washed with pure water and dried to obtain a TiO2 / MoS2 composite film; Step 3, Preparation of Au-TiO2 / MoS2 Photoelectrochemical Biosensor (3.1) Evaporating Au metal film with a thickness of 0.2 nm on the surface of TiO2 / MoS2 composite film and cleaning the sample; (3.2) Annealing at 450 °C under low pressure and high purity Ar in a plasma enhanced chemical vapor deposition tube furnace to obtain Au-TiO2 / MoS2 photoanode; (3.3) Cut the Au-TiO2 / MoS2 photoanode into pieces with a size of 1 cm*0.5 cm, purge them with N2, apply the aptamer probe to the surface of the Au-TiO2 / MoS2 photoanode, incubate and dry; (3.4) Rinse the film surface with ultrapure water and dry it naturally to obtain the Au-TiO2 / MoS2 photoelectrochemical biosensor.

2. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (1.1), the mass ratio of TiO2, ethyl cellulose, glass powder and Span is 1:0.3:0.3125:0.0375; the volume ratio of butyl carbitol and butyl carbitol acetate in the mixed solution of butyl carbitol and butyl carbitol acetate is 1:

1.

3. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (1.2), the stirring is performed by an electronic stirrer at a speed of 800-1200 rpm and a stirring time of 12 to 36 hours.

4. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (1.3), the ball milling is performed using a planetary ball mill with a rotation speed of 400 to 500 rpm, and the ball milling time is 5 to 10 hours.

5. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (1.5), the thickness of the TiO2 film is 50-100 um, the coating speed is 2-5 mm / s, the drying is performed on a heating table, and the drying temperature is 60°C.

6. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (2.3), the spin coating has a rotation speed of 1500 to 3000 rpm and a time of 30 to 60 s.

7. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (2.4), the Ar flow rate in the plasma enhanced chemical vapor deposition tube furnace is 30 to 50 sccm, and the gas pressure in the chamber is 10 to 30 Pa.

8. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (3.2), the Ar flow rate in the plasma enhanced chemical vapor deposition tube furnace is 30 to 50 sccm, and the gas pressure in the chamber is 10 to 30 Pa.

9. The method for preparing the Au-TiO2 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (3.3), the aptamer probe is a DNA aptamer probe of serotonin; the incubation temperature is 4° C., and the incubation time is 12 to 15 hours.

10. An application of Au-TiO2 / MoS2 photoelectrochemical biosensor, characterized in that: The Au-TiO2 / MoS2 photoelectrochemical biosensor prepared according to claim 1 is used for the detection of serotonin.

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