Preparation method and application of Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor

Abstract

The invention provides a preparation method of an Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor and an application of the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor. Comprising the following steps: step 1, preparing a ZnIn2S4 thin film; step 2, preparing a ZnIn2S4 / MoS2 composite thin film; and step 3, preparation of the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor. The invention also relates to an application of the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor. According to the preparation method, the MoS2 layer and the ZnIn2S4 thin film are efficiently combined to form a ZnIn2S4 / MoS2 heterojunction, so that the compounding of photo-induced electrons and holes is effectively inhibited; wherein Van der Waals force generated between the MoS2 layer and the ZnIn2S4 film is beneficial to adsorption of an aptamer of serotonin, so that the sensitivity and the specificity of the sensor are improved; in the combination process of the MoS2 layer and the ZnIn2S4 thin film, the hydrophilicity of the ZnIn2S4 thin film is improved by the MoS2 layer, so that serotonin is detected by the biosensor.

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-ZnIn2S4 / MoS2 photoelectrochemical biosensor. Background Art

[0002] At present, depression has become a very serious social problem. As a key depression marker, serotonin has great potential in depression screening. Common serotonin detection technologies include fluorescence method, gas chromatography, etc.; these methods have problems such as long testing time, expensive equipment, and complicated testing process. Photoelectrochemical biosensors have the advantages of high sensitivity, small detection limit, low cost, and low equipment requirements, which are suitable for the application scenario of depression screening.

[0003] As a ternary metal sulfide, ZnIn2S4 has excellent optical properties and catalytic stability, and has the advantages of low cost, low toxicity, and easy preparation. It overcomes the disadvantage of traditional sulfide catalysts being susceptible to light corrosion. Among ternary metal sulfides, ZnIn2S4 is the only compound with a layered structure, which can be used as one of the advantageous materials for building biosensors. However, there are many interfering substances in the relevant test environment of serotonin, and the concentration to be measured is very low, which puts higher requirements on the detection specificity and sensitivity of biosensors. Therefore, it is a very critical factor to be able to stably anchor the biological probe on the surface of the semiconductor photoelectrode. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method and application of an Au-ZnIn2S4 / 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-ZnIn2S4 / MoS2 photoelectrochemical biosensor, comprising the following steps:

[0007] Step 1, preparation of ZnIn2S4 thin film

[0008] (1.1) Clean 3.3 cm × 5 cm FTO, soak it in pure water, blow it clean with N2, and move it to the reactor;

[0009] (1.2) Dissolve ZnCl2, InCl3·3H2O and CH4N2S in a mixed solution of pure water and anhydrous ethanol, stir evenly to obtain a reaction precursor solution, transfer the reaction precursor solution to a reactor containing FTO, and perform hydrothermal growth in a constant temperature forced air drying oven;

[0010] (1.3) After the reaction is completed, quickly cool the reactor to room temperature and take out the sample;

[0011] (1.4) Clean the sample and move it to a constant temperature air drying oven for drying to obtain a ZnIn2S4 thin film;

[0012] Step 2, preparation of ZnIn2S4 / MoS2 composite film

[0013] (2.1) Transfer 0.0065 g of ammonium tetrathiomolybdate into 1 mL of N,N-dimethylformamide and sonicate for 30 minutes to obtain a homogeneous solution A;

[0014] (2.2) Cut the ZnIn2S4 film into 3.3 cm × 3.3 cm pieces and purge them with N2;

[0015] (2.3) Solution A is evenly attached to the ZnIn2S4 film by spin coating technology and allowed to stand and dry at room temperature;

[0016] (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, washed with pure water, and dried naturally to obtain a ZnIn2S4 / MoS2 composite film;

[0017] Step 3, Preparation of Au-ZnIn2S4 / MoS2 Photoelectrochemical Biosensor

[0018] (3.1) Using high vacuum evaporation coating technology, evaporate Au metal film with a thickness of 0.2 nm on the surface of ZnIn2S4 / MoS2 composite film, and clean the sample;

[0019] (3.2) Annealing at 400 °C in a plasma enhanced chemical vapor deposition tube furnace under low pressure and high purity Ar atmosphere to obtain Au-ZnIn2S4 / MoS2 photoanode;

[0020] (3.3) Cut the Au-ZnIn2S4 / MoS2 photoanode into 1 cm × 0.5 cm pieces, purge them with N2, coat the aptamer probe on the surface of the Au-ZnIn2S4 / MoS2 photoanode, and incubate;

[0021] (3.4) Rinse the film surface with pure water and dry it naturally to obtain the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor.

[0022] Preferably, in (1.2), the molar concentration ratio of ZnCl2, InCl3·3H2O and CH4N2S is 1:2:4, the volume ratio of pure water and anhydrous ethanol is 90:10; the hydrothermal growth temperature is 120-180°C, and the hydrothermal growth time is 6-14h.

[0023] Preferably, in (1.4), the method for cleaning the sample is to first rinse it with pure water for 3 times, and then rinse it with anhydrous ethanol for 3 times.

[0024] Preferably, in (1.4), the drying temperature is a constant temperature of 60° C., and the drying time is 2 to 6 hours.

[0025] Preferably, in (2.3), the spin coating speed in the spin coating technology is 1500-3000 rpm, and the spin coating time is 30-60 s.

[0026] Preferably, in (2.4), the Ar flow rate in the plasma enhanced chemical vapor deposition tube furnace is 25 to 50 sccm, and the gas pressure in the chamber is 10 to 40 Pa.

[0027] Preferably, in (3.2), the Ar flow rate in the plasma enhanced chemical vapor deposition tube furnace is 25 to 50 sccm, and the gas pressure in the chamber is 10 to 40 Pa.

[0028] Preferably, in (3.3), the aptamer probe is a DNA aptamer probe of serotonin.

[0029] Preferably, in (3.3), the incubation temperature is 4° C. and the incubation time is 12 to 14 hours.

[0030] The present invention also relates to the application of the aforementioned Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor, wherein the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor prepared according to claim 1 is used for the detection of serotonin.

[0031] The present invention has the following advantages:

[0032] (1) The method of the present invention hydrothermally grows a uniform ZnIn2S4 thin film with a photoelectric performance of 2 mW / cm 2 It reaches the 0.2 mA level under low light intensity, leaving ample room for photoelectric response regulation for subsequent incubation of aptamers and material detection, which is beneficial to improving the sensitivity of semiconductor photoelectrochemistry.

[0033] (2) The method involved in the present invention efficiently combines the MoS2 layer with the ZnIn2S4 film to form a ZnIn2S4 / MoS2 heterojunction, which effectively inhibits the recombination of photogenerated electrons and holes. The van der Waals force generated between the MoS2 layer and the ZnIn2S4 film helps to adsorb the aptamer of serotonin, thereby improving its sensitivity and specificity; and the MoS2 layer improves the hydrophilicity of the ZnIn2S4 film, thereby realizing the detection of serotonin by the biosensor.

[0034] (3) When the Au nanolayer is fixed by the evaporation technology of the present invention, an Au-S bond is formed with the MoS2 layer on the surface of the ZnIn2S4 / MoS2 photoanode, thereby making the Au bond more firmly, which not only effectively improves the stability of the sensor, but also improves the carrier utilization efficiency, so that the photoelectric response of the sensor is effectively enhanced.

[0035] (4) The Au-S bonds generated by the Au nanolayer on the surface of the Au-ZnIn2S4 / MoS2 photoelectric biosensor prepared by the present invention and the serotonin aptamer provide more binding sites for the specific probe, thereby improving the sensitivity and accuracy of the sensor and broadening the linear detection area of ​​the photoelectric biosensor.

[0036] (5) Au-ZnIn2S prepared by the method of the present invention 4 / MoS2 photoelectric biosensor has the advantages of high sensitivity and excellent specificity, and has application potential and wide expansion capabilities in areas such as early screening of depression markers. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a curve diagram of the detection characteristics of Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor for serotonin;

[0038] Figure 2 This is a diagram for evaluating the detection specificity of Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor for serotonin. DETAILED DESCRIPTION

[0039] 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.

[0040] Example

[0041] This embodiment relates to a method for preparing an Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor, comprising the following steps:

[0042] Step 1, preparation of ZnIn2S4 thin film

[0043] (1) Take out the FTO sample and cut it into 3.3 cm × 5 cm size. Ultrasonicate it in a solution of FTO cleaning solution: pure water = 1:9 for 10-20 minutes, then put it in anhydrous ethanol for 10-20 minutes, and then put it in pure water for 10-20 minutes. Take out the sample and purge it with N2, and move it to a 200 ml reactor;

[0044] (2) 0.1363 g ZnCl2, 0.5865 g InCl3·3H2O, and 0.3045 g CH4N2S were dissolved in a mixed solution of 90 ml pure water and 10 ml anhydrous ethanol, and stirred on a magnetic stirrer at 400 rpm for 30 minutes to obtain a reaction precursor solution, which was slowly poured into a reactor containing FTO, and hydrothermally grown in a constant temperature forced air drying oven at 160°C for 7 hours;

[0045] (3) At the moment the hydrothermal reaction is finished, use heat-resistant gloves to move the reactor under water to quickly cool it down for 15 minutes, remove the reactor liner, and use tweezers to remove the sample after the liner cools naturally to room temperature;

[0046] (4) The deposited material on the back of the sample was wiped with a dust-free cloth, and after being cleaned with pure water and anhydrous ethanol for three times each, it was placed in a constant temperature forced air drying oven at 60°C and dried for 2 hours to obtain a ZnIn2S4 thin film.

[0047] Step 2, preparation of ZnIn2S4 / MoS2 composite film

[0048] (1) Dissolve 0.0065 g of ammonium tetrathiomolybdate in 1 ml of N,N-dimethylformamide and sonicate for 30 minutes to obtain a uniform solution A;

[0049] (2) Cut the ZnIn2S4 film into 3.3 cm × 3.3 cm pieces and purge them with N2;

[0050] (3) Spin coating was performed by dropping 273 μl of uniform solution A onto a 3.3 cm × 3.3 cm ZnIn2S4 film at a speed of 2000 rpm for 50 s and leaving the film to dry completely at room temperature.

[0051] (4) placing the sample in a heating furnace of a plasma enhanced chemical vapor deposition tube furnace, controlling the flow of argon gas in the furnace, with a flow rate of 30 sccm, maintaining the gas pressure at 15 Pa, heating the temperature to 400°C at a rate of 10°C / min, keeping the temperature for 1 hour, washing with pure water, and drying to obtain a ZnIn2S4 / MoS2 composite film;

[0052] Step 3, Preparation of Au-ZnIn2S4 / MoS2 Photoelectrochemical Biosensor

[0053] (1) Using high vacuum evaporation coating technology to evaporate Au metal film on the surface of ZnIn2S4 / MoS2 composite film, the thickness of Au metal film is 0.2nm, and the sample is cleaned;

[0054] (2) The sample was placed in a heating furnace of a plasma enhanced chemical vapor deposition tube furnace, and the temperature was raised to 400°C at a rate of 10°C / min under argon protection at a flow rate of 30 sccm and a pressure of 15 Pa. The temperature was kept at this temperature for 1 hour to obtain an Au-ZnIn2S4 / MoS2 photoanode.

[0055] (3) Prepare 1 uM 5-HT aptamer probe, cut the obtained Au-ZnIn2S4 / MoS2 photoanode into 1 cm × 0.5 cm size, purge it with N2, coat the aptamer probe on the surface of Au-ZnIn2S4 / MoS2 photoanode, and incubate it in a refrigerator at 4 °C for 14 hours;

[0056] (4) Rinse the film surface with pure water and dry it naturally to obtain the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor.

[0057] The performance test of the product prepared in the above embodiment is carried out as follows:

[0058] The detected solutions of different concentrations were coated on the surface of the prepared Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor. After incubation at 37°C for 30 minutes, the electrode surface was fully rinsed with pure water and dried. The Pt electrode was used as the working electrode, the Ag / AgCl electrode was used as the negative electrode, and the Ag / AgCl electrode was used as the reference electrode. 2 Under the irradiation of monochromatic light with a wavelength of 365nm, the sensing detection characteristics of the series of sensors were tested by the time-current curve function of the electrochemical workstation.

[0059] Figure 1 The above is the detection characteristic curve of Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor for serotonin. It can be clearly seen that the photocurrent signal decreases significantly with the increase of serotonin concentration, which further proves that the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor prepared in the embodiment of the present invention can detect the concentration of serotonin substances, and its sensing performance is inhibitory. The Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor prepared in the embodiment of the present invention not only detects a large photocurrent signal, the difference is suppressed from 30uA to 18uA, and shows a good linear relationship, which proves that the prepared Au-Zn ZnIn2S4 / MoS2 photoelectrochemical biosensor is very sensitive to changes in serotonin concentration. The detection line width is 10 -11 ~10 -8 g / mL, detection limit 0.31×10 -11 g / mL (S / N=3).

[0060] Figure 2In order to test the detection specificity of the prepared Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor to serotonin, the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor of the present invention has a very obvious light response signal to serotonin, with a difference of about 0.02 mA / cm 2 , while the responses to other series of interference items (dopamine, tryptophan, bovine serum albumin, glucose) are very weak, much smaller than the light response signal value of the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor of the present invention to serotonin, which further proves that the Au-ZnIn2S4 / MoS2 photoelectric biosensor prepared by the method of the present invention has a strong detection specificity for serotonin after fixing the serotonin aptamer.

[0061] In summary, the present invention firstly grows a uniform ZnIn2S4 thin film through hydrothermal growth, and forms a heterojunction in which the MoS2 nanolayer and the ZnIn2S4 thin film are effectively combined, thereby suppressing the recombination of photogenerated electrons and holes, providing an effective binding site for the DNA single-stranded aptamer, and solving the non-hydrophilic defect of the ZnIn2S4 thin film. 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, thereby greatly improving the sensitivity and specificity of the sensor.

[0062] 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-ZnIn2S4 / MoS2 photoelectrochemical biosensor, characterized in that: The following steps are involved: Step 1, preparation of ZnIn2S4 thin film (1.1) Clean a 3.3 cm × 5 cm FTO, soak it in pure water, blow it clean with N2, and move it to the reactor; (1.2) Dissolve ZnCl2, InCl3·3H2O and CH4N2S in a mixed solution of pure water and anhydrous ethanol, stir evenly to obtain a reaction precursor solution, transfer the reaction precursor solution to a reactor containing FTO, and perform hydrothermal growth in a constant temperature forced air drying oven; (1.3) After the reaction is completed, quickly cool the reactor to room temperature and take out the sample; (1.4) Clean the sample and move it to a constant temperature air drying oven for drying to obtain a ZnIn2S4 thin film; Step 2, preparation of ZnIn2S4 / MoS2 composite film (2.1) Transfer 0.0065 g of ammonium tetrathiomolybdate into 1 mL of N,N-dimethylformamide and sonicate for 30 minutes to obtain a homogeneous solution A; (2.2) Cut the ZnIn2S4 film into 3.3 cm × 3.3 cm pieces and purge them with N2; (2.3) Solution A is evenly attached to the ZnIn2S4 film by spin coating technology and allowed to stand and 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 low pressure and high purity Ar atmosphere for 1 hour, washed with pure water, and dried naturally to obtain a ZnIn2S4 / MoS2 composite film; Step 3, Preparation of Au-ZnIn2S4 / MoS2 Photoelectrochemical Biosensor (3.1) Using high vacuum evaporation coating technology, evaporate Au metal film with a thickness of 0.2 nm on the surface of ZnIn2S4 / MoS2 composite film, and clean the sample; (3.2) Annealing at 400 °C in a plasma enhanced chemical vapor deposition tube furnace under low pressure and high purity Ar atmosphere to obtain Au-ZnIn2S4 / MoS2 photoanode; (3.3) Cut the Au-ZnIn2S4 / MoS2 photoanode into 1 cm × 0.5 cm pieces, purge them with N2, coat the aptamer probe on the surface of the Au-ZnIn2S4 / MoS2 photoanode, and incubate; (3.4) Rinse the film surface with pure water and dry it naturally to obtain the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor.

2. The method for preparing the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (1.2), the molar concentration ratio of ZnCl2, InCl3·3H2O and CH4N2S is 1:2:4, the volume ratio of pure water and anhydrous ethanol is 90:10; the hydrothermal growth temperature is 120-180°C, and the hydrothermal growth time is 6-14h.

3. The method for preparing the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (1.4), the method for cleaning the sample is to first rinse it with pure water for 3 times and then rinse it with anhydrous ethanol for 3 times.

4. The method for preparing the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (1.4), the drying temperature is a constant temperature of 60° C., and the drying time is 2 to 6 hours.

5. The method for preparing the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (2.3), the spin coating speed in the spin coating technology is 1500-3000 rpm, and the spin coating time is 30-60 s.

6. The method for preparing the Au-ZnIn2S4 / 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 25 to 50 sccm, and the gas pressure in the chamber is 10 to 40 Pa.

7. The method for preparing the Au-ZnIn2S4 / 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 25 to 50 sccm, and the gas pressure in the chamber is 10 to 40 Pa.

8. The method for preparing the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (3.3), the aptamer probe is a DNA aptamer probe of serotonin.

9. The method for preparing the Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor according to claim 1, characterized in that: In (3.3), the incubation temperature is 4°C and the time is 12 to 14 hours.

10. An application of Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor, characterized in that: The Au-ZnIn2S4 / MoS2 photoelectrochemical biosensor prepared according to claim 1 is used for the detection of serotonin.

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