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

Abstract

The present invention provides a preparation method and application of an Au-TiO2 / MoS2 photoelectrochemical biosensor; comprising: step 1, preparation of a TiO2 thin film; step 2, preparation of a TiO2 / MoS2 composite thin film; step 3, preparation of an Au-TiO2 / MoS2 photoelectrochemical biosensor. The present invention also relates to the application of an Au-TiO2 / MoS2 photoelectrochemical biosensor in detecting serotonin, a marker of depression. The present invention first prepares a uniform TiO2 thin film by a slurry coating technique, and forms a heterojunction in which the MoS2 nanolayer and the TiO2 thin film are effectively combined, thereby improving electron utilization and providing an effective binding site for a DNA single-stranded aptamer; the ultra-thin Au nanolayer deposited by a high vacuum evaporation coating technique forms an effective carrier transport system, improves the photoelectrochemical performance, and further increases the binding sites for the DNA single-stranded aptamer, greatly improving the sensitivity and specificity of the sensor. The present invention has application potential and broad expansion capabilities in the field of early screening of depression markers.

Description

Technical Field

[0001] The present invention belongs to the field of biosensor technology, and in particular relates to a preparation method and application of an Au-TiO2 / MoS2 photoelectrochemical biosensor. Background Art

[0002] In recent years, depression has become a serious social problem. As a key depression biomarker, the neurotransmitter serotonin holds great potential for widespread depression screening. Currently, common serotonin detection techniques include fluorescence, gas chromatography, and electrochemical methods. However, these methods suffer from drawbacks such as lengthy testing times and expensive equipment. Photoelectrochemical biosensors offer significant advantages over these methods, including simple equipment, efficient testing, high sensitivity, and low cost.

[0003] TiO2 is a classic semiconductor metal oxide with numerous advantages, including stable performance, high electron mobility, and good biocompatibility, making it a promising material for biosensor construction. However, the presence of numerous interfering substances in serotonin-related testing environments, coupled with very low concentrations, places higher demands on the specificity and sensitivity of biosensors. Therefore, the ability to stably anchor biological probes on the surface of semiconductor photoelectrodes is crucial. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of an Au-TiO2 / MoS2 photoelectrochemical biosensor.

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

[0006] The present invention relates to a method for preparing an Au-TiO2 / MoS2 photoelectrochemical biosensor, comprising the following steps:

[0007] Step 1, preparation of TiO2 thin film

[0008] (1.1) Mix appropriate amounts of TiO2, ethyl cellulose, glass powder, and Span in a mixed solution of butyl carbitol and butyl carbitol acetate, and stir evenly to obtain TiO2 slurry precursor 1;

[0009] (1.2) Fully stirring TiO2 slurry precursor 1 to obtain TiO2 slurry precursor 2;

[0010] (1.3) Filter and ball-mill the TiO2 slurry precursor 2 to obtain TiO2 slurry;

[0011] (1.4) After cleaning the 12 cm*12 cm FTO, soak it in deionized water and purge it with N2;

[0012] (1.5) Using the coating technology, evenly apply TiO2 film on a 12 cm*12 cm FTO sample and dry it;

[0013] (1.6) Annealing at 500°C in a muffle furnace to obtain a TiO2 thin film;

[0014] Step 2, preparation of TiO2 / MoS2 composite film

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

[0016] (2.2) Cut the TiO2 film into 4 cm x 4 cm pieces and purge them with N2;

[0017] (2.3) Using spin coating technology, evenly spin-coat 400 μL of the solution onto a 4 cm x 4 cm TiO2 film and allow to dry at room temperature.

[0018] (2.4) Place the sample in a plasma-enhanced chemical vapor deposition tube furnace. Under low pressure and high-purity Ar atmosphere, heat the sample to 400°C at 10°C / min and hold for 1 hour. Rinse with pure water and dry to obtain a TiO2 / MoS2 composite film.

[0019] Step 3, Preparation of Au-TiO2 / MoS2 Photoelectrochemical Biosensor

[0020] (3.1) Using high-vacuum evaporation technology (within the evaporation chamber, a solid material placed on a tungsten boat is controlled by an electric current to reach its melting point. The temperature is then raised to the evaporation point, at which point the material gains enough energy to leave the surface and transform into vapor. The high vacuum prevents the vapor from reacting or scattering with other substances during its movement, allowing it to condense on the substrate and form a thin film). A 0.2 nm thick Au film is evaporated onto the surface of the TiO2 / MoS2 composite film, and the sample is cleaned.

[0021] (3.2) Annealing at 450°C in a plasma-enhanced chemical vapor deposition tube furnace under low pressure and high-purity Ar to obtain the Au-TiO2 / MoS2 photoanode;

[0022] (3.3) Cut the Au-TiO2 / MoS2 photoanode into 1 cm x 0.5 cm pieces, purge them with N2, coat the aptamer probe on the surface of the Au-TiO2 / MoS2 photoanode, incubate, and dry.

[0023] (3.4) Rinse the film surface with ultrapure water and dry it naturally to obtain the Au-TiO2 / MoS2 photoelectrochemical biosensor.

[0024] Preferably, in (1.1), the mass ratio of TiO2, ethyl cellulose, glass powder and Span is 1:0.3:0.3125:0.0375; and 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 thickness of the TiO2 film is 50-100 um, the speed of the scraping is 2-5 mm / s, the drying is performed 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 for 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 as follows: first, a TiO2 thin film is prepared; then, a heterojunction formed by the effective combination of a MoS2 nanolayer and a TiO2 thin film is used to prepare a TiO2 / MoS2 composite thin film, thereby improving electron utilization and providing effective binding sites for a DNA single-stranded aptamer; finally, an ultra-thin Au nanolayer is deposited through high-vacuum evaporation coating technology to composite Au with TiO2 / MoS2, forming an effective carrier transport system, improving photoelectrochemical performance, further increasing the binding sites for a DNA single-stranded aptamer, and significantly improving the sensitivity and specificity of the sensor, ultimately constructing an Au-TiO2 / MoS2 photoelectrochemical biosensor.

[0033] The present invention also relates to the Au-TiO2 / MoS2 photoelectrochemical biosensor prepared above for detecting serotonin.

[0034] The present invention has the following advantages:

[0035] (1) The method involved in the present invention efficiently combines the MoS2 layer with the TiO2 film to form a TiO2 / MoS2 heterojunction, effectively increasing the light absorption range of the sensor, thereby improving the electron utilization rate; since the van der Waals force generated between the MoS2 layer and TiO2 helps to adsorb the aptamer of serotonin, the sensitivity and specificity of the semiconductor photoelectrochemistry are improved.

[0036] (2) The method of the present invention forms Au-S bonds with the MoS2 layer on the surface of the TiO2 / MoS2 composite film when the gold nanolayer is fixed by evaporation technology, thereby more firmly binding Au, which not only effectively improves the stability of the sensor, but also improves the carrier utilization efficiency, and ultimately enhances the photocurrent response of the sensor; in addition, the nano-gold layer on the surface of the Au-TiO2 / MoS2 photoelectric biosensor prepared by the present invention generates Au-S bonds with the serotonin aptamer, providing more binding sites for the specific probe, thereby improving the sensitivity and accuracy of the sensor and broadening the linear detection area of ​​the sensor.

[0037] (3) The Au-TiO2 / MoS2 photoelectric biosensor prepared by the method of the present invention effectively combines Au with the TiO2 / MoS2 heterojunction. The advantages of MoS2 and Au complement each other, achieving an effective improvement in the performance of the photoelectrochemical sensor, while improving the sensitivity and specificity of the semiconductor chemical sensor and broadening the linear detection area.

[0038] (4) The Au-TiO2 / MoS2 photoelectric biosensor prepared by the method of the present invention has the advantages of high sensitivity and excellent specificity, and has broad application potential and expansion capabilities in the fields of early screening of depression markers. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the linear curve of the Au-TiO2 / MoS2 photoelectrochemical biosensor for detecting serotonin;

[0040] Figure 2 This is a diagram showing the specificity evaluation of the Au-TiO2 / MoS2 photoelectrochemical biosensor for serotonin. DETAILED DESCRIPTION

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

[0042] This embodiment relates to a method for preparing an Au-TiO2 / MoS2 photoelectrochemical biosensor, comprising the following steps:

[0043] Step 1, preparation of TiO2 thin film

[0044] ① 8 g of TiO2 powder, 2.4 g of ethyl cellulose, 2.5 g of glass powder, and 0.3 g of Span were stirred evenly with a stirring rod. 15 mL of butyl carbitol and 15 mL of butyl carbitol acetate were added and continued to stir evenly with a stirring rod to obtain TiO2 slurry precursor 1;

[0045] ② Move the TiO2 slurry precursor 1 to an electronic stirrer at a speed of 1000 rpm and stir at a constant temperature and humidity for 24 hours to obtain TiO2 slurry precursor 2;

[0046] ③ After the TiO2 slurry precursor 2 was rolled and filtered once in a three-roll mill, it was ball-milled in a planetary ball mill at a speed of 500 rpm for 8 hours to obtain a TiO2 slurry;

[0047] ④ Take out a 12 cm*12 cm FTO sample, ultrasonicate it in a solution of FTO cleaning solution: pure water 1:9 for 10-20 minutes, then ultrasonicate it in anhydrous ethanol for 10-20 minutes, then ultrasonicate it in pure water for 10-20 minutes, take out the sample and purge it with N2;

[0048] ⑤ Move the sample onto the coating apparatus substrate, adjust the coating apparatus height to 100 μm, and the coating speed to 2 mm / s. After the TiO2 slurry is evenly applied on the sample, start coating. After coating, place the sample on a 60°C constant temperature heating table to dry for 3.5 hours.

[0049] ⑥ Heat the dried sample to 500°C in a muffle furnace at a rate of 10°C / min and keep it at that temperature for 2 hours to obtain a TiO2 film;

[0050] Step 2, preparation of TiO2 / MoS2 composite film

[0051] ① Dissolve 0.013 g of ammonium tetrathiomolybdate in 1 mL N , N -dimethylformamide; ultrasonicate for 30 minutes to obtain a homogeneous solution;

[0052] ② Cut the TiO2 film into 4 cm*4 cm samples and purge them with N2;

[0053] ③Using spin coating technology, evenly apply 400 μL of the solution on a 4 cm*4 cm TiO2 film at a speed of 2000 rpm for 50 s, and let it dry at room temperature.

[0054] ④ Place the sample in a plasma-enhanced chemical vapor deposition tube furnace, control the flow of argon gas in the furnace at a flow rate of 30 sccm, maintain the gas pressure at 15 Pa, and increase the temperature to 400°C at a rate of 10°C / min. Keep the temperature for 1 hour, rinse with pure water, and dry to obtain a TiO2 / MoS2 composite film;

[0055] Step 3, Preparation of Au-TiO2 / MoS2 Photoelectrochemical Biosensor

[0056] ① Using high vacuum evaporation coating technology, evaporate Au metal film with a thickness of 0.2 nm on the surface of TiO2 / MoS2 composite film, and clean the sample;

[0057] ② Place the sample in a plasma-enhanced chemical vapor deposition tube furnace, control the flow of argon gas in the furnace at a flow rate of 30 sccm, maintain the gas pressure at 15 Pa, and increase the temperature to 450°C at a rate of 10°C / min and keep it at that temperature for 1 hour to obtain the Au-TiO2 / MoS2 photoanode;

[0058] ③ Prepare 1 μM 5-HT aptamer probe, cut the obtained Au-TiO2 / MoS2 photoanode into 1 cm*0.5 cm pieces, purge it with N2, coat the aptamer probe on the surface of the obtained Au-TiO2 / MoS2 photoanode, and incubate it in a 4°C refrigerator for 14 hours;

[0059] ④ Rinse the film surface with ultrapure water and dry it naturally to obtain the Au-TiO2 / MoS2 photoelectrochemical biosensor.

[0060] Conduct performance tests on the products obtained during the preparation process

[0061] The test solution of different concentrations was applied to the surface of the prepared Au-TiO2 / MoS2 photoelectrochemical biosensor. After incubation at constant temperature for 20 minutes, the electrode surface was thoroughly cleaned and dried. The working electrode was used, the Pt electrode was the negative electrode, and the Ag / AgCl electrode was the reference electrode. The light intensity was 2 mW / cm 2 Under the irradiation of 365 nm monochromatic light, the sensing detection characteristics of the series of sensors were tested by the time-current curve function of the electrochemical workstation.

[0062] Figure 1 The characteristic curve of the Au-TiO2 / MoS2 photoelectrochemical biosensor for the depression marker serotonin is shown. It can be clearly seen that the photocurrent signal decreases with the increase of serotonin concentration, proving 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).

[0063] Figure 2 In order to test the detection specificity of the prepared Au-TiO2 / MoS2 photoelectrochemical biosensor for serotonin, the Au-TiO2 / MoS2 photoelectrochemical biosensor of the present invention has a very obvious light response signal (close to 3uA / cm 2 ), while the responses to other series of interference items (dopamine, glucose, bovine serum albumin, NaCl) are weak, which are much smaller than the very obvious light response signal value of the Au-TiO2 / MoS2 photoelectrochemical biosensor of the present invention to serotonin; therefore, it is shown that the Au-TiO2 / MoS2 photoelectrochemical biosensor prepared by the method of the present invention has a strong detection specificity for serotonin after the serotonin aptamer is fixed.

[0064] It can be seen that the present invention first prepares a uniform TiO2 thin film through slurry coating technology, and the heterojunction of the MoS2 nanolayer and the TiO2 thin film is effectively combined, which improves the electron utilization rate and provides an effective binding site for the DNA single-stranded aptamer. 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 of the DNA single-stranded aptamer, greatly improving the sensitivity and specificity of the sensor.

[0065] 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 variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An application of an Au-TiO2 / MoS2 photoelectrochemical biosensor, characterized in that: Au-TiO2 / MoS2 photoelectrochemical biosensor for the detection of serotonin; The preparation method of the Au-TiO2 / MoS2 photoelectrochemical biosensor comprises the following steps: 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, and stir evenly to obtain TiO2 slurry precursor 1; (1.2) Fully stirring TiO2 slurry precursor 1 to obtain TiO2 slurry precursor 2; (1.3) Filter and ball-mill the TiO2 slurry precursor 2 to obtain TiO2 slurry; (1.4) After cleaning the 12 cm*12 cm FTO, soak it in deionized water and purge it with N2; (1.5) Apply a TiO2 film evenly on a 12 cm*12 cm FTO sheet and dry. (1.6) Annealing at 500°C in a muffle furnace to obtain a TiO2 thin film; Step 2, preparation of TiO2 / MoS2 composite film (2.1) Transfer 0.013 g of ammonium tetrathiomolybdate to 1 mL N , N -dimethylformamide; ultrasonicate for 30 minutes to obtain a homogeneous solution; (2.2) Cut the TiO2 film into 4 cm x 4 cm pieces and purge them with N2; (2.3) Spin-coat 400 μL of the solution onto a 4 cm x 4 cm TiO2 film and allow to dry at room temperature. (2.4) Place the sample in a plasma-enhanced chemical vapor deposition tube furnace. Under low pressure and high-purity Ar atmosphere, heat the sample to 400°C at 10°C / min and hold for 1 hour. Rinse with pure water and dry to obtain a TiO2 / MoS2 composite film. Step 3, Preparation of Au-TiO2 / MoS2 Photoelectrochemical Biosensor (3.1) Evaporate a 0.2 nm thick Au film on the surface of the TiO2 / MoS2 composite film and clean the sample. (3.2) Annealing at 450°C in a plasma-enhanced chemical vapor deposition tube furnace under low pressure and high-purity Ar to obtain the Au-TiO2 / MoS2 photoanode; (3.3) Cut the Au-TiO2 / MoS2 photoanode into 1 cm x 0.5 cm pieces, purge them with N2, coat the aptamer probe on 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 use of 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; and the volume ratio of butyl carbitol to butyl carbitol acetate in the mixed solution of butyl carbitol and butyl carbitol acetate is 1:

1.

3. The use of 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 for a stirring time of 12 to 36 hours.

4. The use of 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 use of 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, and the drying is performed on a heating table at a drying temperature of 60°C.

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

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

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