CN112461905B - Construction method of a novel light-assisted bipolar self-powered aptamer sensor device - Google Patents

Abstract

The invention provides a construction method of a novel light-assisted bipolar self-powered aptamer sensor, while using a multimeter as a direct readout strategy, the steps are as follows: Step 1, prepare the photoanode material black titanium dioxide (B-TiO ₂ ) and photocathode Materials Three-dimensional nitrogen-doped graphene hydrogel loaded cuprous oxide nanospheres (Cu ₂ O/3DNGH); step 2, constructing a photo-assisted bipolar self-powered aptasensor for detecting sulfamethazine. The novel light-assisted bipolar self-powered aptamer sensor constructed by the present invention does not need an external power supply, the detection device itself supplies energy for the detection process, and a simple multimeter is used as a direct readout strategy, which is easy to miniaturize and portable, and realizes on-site detection . At the same time, the anode and cathode of the sensor are both made of semiconductor materials, avoiding the use of bioactive components and noble metal electrode Pt, greatly improving the efficiency of solar energy utilization and reducing production costs.

Description

Construction method of a novel light-assisted bipolar self-powered aptamer sensor device

technical field

The invention belongs to the technical field of electrochemical biosensing, and relates to a construction method of a self-powered aptamer sensor device based on a light-assisted bipolar fuel cell.

Background technique

Self-powered electrochemical sensor is an emerging electrochemical detection technology. Unlike traditional electrochemical sensing systems, self-powered sensors do not require an external power supply and can supply energy for their own sensing process. By changing the concentration of the target Converted to changes in power signals (such as open circuit voltage, current density or power, etc.), to achieve quantitative detection of targets. Self-powered electrochemical sensing technology has unique advantages in promoting sensor miniaturization, convenience, and low cost. For example, no external power supply is required, and only two electrodes (anode and cathode) are used to realize electrochemical detection, which is conducive to miniaturization. ; A simple voltmeter/ammeter can output detection signals, which reduces equipment costs and facilitates detection; in addition, since no additional power is applied, the reaction of some electroactive substances on the electrode surface is avoided, and the specificity of the sensor is improved. .

At present, the research on self-powered electrochemical sensors is mainly realized through the approach of biomass fuel cell (BFC). However, the biomass fuel cell system has biologically active components, and has disadvantages such as complicated operation, harsh reaction conditions and instability, and can only realize a single energy conversion of biomass energy/electric energy. To overcome these problems, self-powered electrochemical sensors based on photofuel cells (PFCs) have attracted extensive attention from researchers. The PFC type self-powered electrochemical sensor uses photosensitive semiconductor materials instead of biocatalysts to convert solar and chemical energy into electrical energy. It is a two-dimensional energy conversion device with fast electron transmission, simple operation, stable physical and chemical properties, and high output performance. According to the number of photoelectrodes in the battery, PFC is divided into unipolar PFC and bipolar PFC. At present, most studies are mainly focused on unipolar PFC, that is, only one electrode is a photosensitive material that can respond to sunlight, and the other electrode is selected from the noble metal catalyst Pt, the dye Prussian blue (PB), or some electrocatalysts. In order to improve the efficiency of solar energy utilization and reduce the use of noble metal catalysts, it is meaningful to design a bipolar PFC in which the cathode and anode are semiconductor photosensitive materials. The construction of a bipolar PFC is usually based on the fact that the n-type semiconductor photoanode has a higher Fermi level than the p-type semiconductor photocathode, ensuring that the driving electrons flow from the photoanode to the photocathode. In addition, in previous reports, self-powered electrochemical sensors still mainly rely on electrochemical workstations to collect and process signal data, making it difficult to achieve on-site detection, which hinders their practical application. Therefore, the present invention adopts the simple equipment of the multimeter as a direct readout strategy, replaces the bulky instrument of the electrochemical workstation, and designs a portable self-powered electrochemical sensing device that is convenient for on-site detection.

Sulfamethazine (SMZ) is a broad-spectrum antibiotic. As a feed additive commonly used in veterinary medicine and animal husbandry, it plays an important role in the prevention and treatment of livestock and poultry diseases. However, the residue problem in animal-derived food caused by excessive use of SMZ seriously threatens human health. Currently, methods for detecting SMZ include enzyme-linked immunoassay, high-performance liquid chromatography, and fluorescent immunoassay. Although these methods are accurate, most of them are time-consuming, labor-intensive, and complicated to operate, and have limitations in practical application. Therefore, it is very necessary to develop a simple, fast, portable and low-cost analytical method.

Contents of the invention

The purpose of the present invention is to provide a portable light-assisted bipolar fuel cell self-powered aptamer sensor that integrates the advantages of fast, simple, miniaturized, and low-cost for SMZ detection, and uses a simple multimeter instead of an electrochemical workstation as a Read out the policy directly.

The construction of the self-powered sensor device in the present invention includes the following steps:

Step 1. Preparation of photoanode material black titanium dioxide (B-TiO ₂ ):

Mix tetrabutyl titanate with ethanol to obtain solution A; mix concentrated nitric acid, ethanol and water to obtain solution B; add solution A dropwise to solution B, stir evenly to obtain mixed solution C, and transfer to stainless steel Carry out solvothermal reaction in an autoclave. After the reaction is completed, the solid product titanium dioxide is obtained; the obtained titanium dioxide and sodium borohydride are thoroughly ground in a mortar, transferred to a porcelain crucible, and calcined and reduced in a tube furnace under an argon atmosphere. After the reaction is completed, the obtained solid product is B-TiO ₂ ;

Step 2. Preparation of photocathode material Three-dimensional nitrogen-doped graphene hydrogel loaded cuprous oxide nanospheres (Cu ₂ O/3DNGH):

First, the graphene oxide dispersion was stirred with urea, and transferred to an autoclave for solvothermal reaction. After the reaction was completed, 3DNGH was obtained. Then, the copper nitrate was dissolved in water, and the hydrazine hydrate solution was dropped into it under magnetic stirring. After fully reacting, it was centrifuged, washed, and vacuum-dried to obtain Cu ₂ O powder. Finally, the obtained Cu ₂ O was mixed with isopropanol and 3-aminopropyltrimethylsilane, stirred evenly, and washed by centrifugation to obtain positively charged surface functionalized Cu ₂ O, and then fully stirred with 3DNGH aqueous solution, thereby The solid product Cu ₂ O/3DNGH was prepared.

Step 3, manufacture of modified electrode:

Disperse B-TiO ₂ and Cu ₂ O/3DNGH obtained in step 1 and step 2 in N,N-dimethylformamide (DMF) to obtain B-TiO ₂ dispersion, Cu ₂ O/3DNGH dispersion solution, B-TiO ₂ , Cu ₂ O/3DNGH dispersion liquid was drop-coated on the ITO electrode with a fixed area, and dried under an infrared lamp. The obtained B-TiO ₂ /ITO electrode was used as a photoanode, and the Cu ₂ O /3DNGH/ITO electrode as photocathode.

Step 4. Construct a light-assisted bipolar self-powered aptamer sensor device for detecting SMZ

Firstly, chitosan (CHIT) solution was drop-coated on the photoanode B-TiO ₂ /ITO, and dried under infrared light. Next, a glutaraldehyde (GA) solution was dropped on the surface of the electrode and left to react at room temperature. After the reaction was completed, it was rinsed with PBS to remove excess GA on the surface of the electrode. Use Tris-HCl as solvent to prepare SMZ aptamer solution, add SMZ aptamer dropwise on the electrode, after a period of reaction, wash with PBS to remove excess unadsorbed aptamer, then add bovine serum albumin dropwise (BSA) solution to block the non-specific active sites, and finally obtain the aptamer-modified photoanode (aptamer/B-TiO ₂ /ITO), and the photocathode Cu ₂ O/3DNGH/ITO constitutes a photo-assisted bipolar self-energy adapter. Ligand sensing devices.

In step 1,

In the solution A, the dosage ratio of tetrabutyl titanate to ethanol is 1-3mL: 0.05-5mL;

In solution B, the dosage ratio of concentrated nitric acid, ethanol and water is 0.05-0.15mL: 0.05-5mL: 0.1-1mL;

When solution A and solution B are mixed, the ratio of tetrabutyl titanate to concentrated nitric acid is 1-3mL: 0.05-0.15mL;

The temperature of the solvothermal reaction is 160-200°C, and the reaction time is 10-14h; the mass ratio of titanium dioxide to sodium borohydride is 3:1; the calcination temperature is 300-400°C, the time is 0.5-1.5h, and the heating rate 10°C/min.

In step 2,

The ratio of graphene oxide dispersion to urea is 50mL:2g, wherein the concentration of graphene oxide dispersion is 1g/mL; the temperature of the solvothermal reaction is 150°C, and the reaction time is 10h.

The dosage ratio of copper nitrate, water, and hydrazine hydrate solution is 0.25g:50mL:4mL; wherein, the concentration of hydrazine hydrate solution is 0.5mol/L.

The dosage ratio of Cu ₂ O, isopropanol and 3-aminopropyltrimethylsilane is 0.1g: 10mL: 0.1mL, and the stirring time is 12-36h.

The ratio of the obtained positively charged surface functionalized Cu ₂ O to the 3DNGH aqueous solution is 25-75mg: 5-15mL, wherein the concentration of the 3DNGH aqueous solution is 1g/mL, and the stirring time is 2-6h.

In step 3, the concentrations of B-TiO ₂ dispersion and Cu ₂ O/3DNGH dispersion are both 1-3 mg/mL; the amounts of B-TiO ₂ and Cu ₂ O/3DNGH dispersion are both 20-40 μL, The fixed area of ITO is 0.09πcm ² ;

In step 4,

The mass percentage concentration of the CHIT is 0.1%, and the dropping amount is 10 μL;

The volume percent concentration of the GA is 2.5%, and the dropping amount is 20 μL; the reaction time between CHIT and GA is 1-2 hours;

The sequence of the SMZ aptamer is: 5′-NH ₂ -TTA GCT TAT GCG TTG GCC GGG ATA AGG ATC CAGCCG TTG TAG ATT TGC GTT CTA ACT CTC-3′; 40 μL, the reaction time is 10-14 hours; the mass percent concentration of BSA is 3%.

The use of the light-assisted bipolar self-powered aptamer sensor device prepared by the present invention for detecting sulfamethazine SMZ, the specific steps are:

(1) Drop different concentrations of SMZ solutions onto the aptamer/B-TiO ₂ /ITO photoanode, and incubate at room temperature for a period of time;

(2) Put the photoanode and photocathode Cu ₂ O/3DNGH/ITO treated in step (1) into the single-chamber electrolytic cell containing PBS, the xenon light source illuminates the two photoelectrodes vertically at the same time, connect the two poles with a multimeter, Collect the potential signal directly; make a standard curve between the potential value and the logarithmic value of the SMZ concentration;

(3) The potential signal of the SMZ solution of unknown concentration was collected by the above method, and substituted into the standard curve to obtain the concentration of the SMZ solution.

In order to verify the accuracy of the collected signals, electrochemical analysis was carried out through the two-electrode system of the electrochemical workstation.

In step (1), the concentration of SMZ is 0.001-100100 ng/mL, specifically 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 50 and 100 ng/mL, and the dropping amount is 10-30 μL;

In step (2), the amount of PBS is 20-30 mL; the intensity of the xenon lamp light source is 25%-100%.

The beneficial effects of the present invention are:

The present invention prepares B-TiO ₂ nanoparticles as the photoanode active material, Cu ₂ O/3DNGH as the photocathode active material, and successfully establishes a light-assisted bipolar self-powered aptamer sensor to realize the analysis and detection of SMZ. Its characteristics and The advantages are stated as follows:

(1) The present invention prepares B-TiO ₂ nanoparticles as the photoanode active material, and Cu ₂ O/3DNGH as the photocathode active material to construct a light-assisted bipolar self-powered aptamer sensor, and the energy levels between the double photoelectrodes match well, Excellent power output performance.

(2) The present invention prepares Cu ₂ O/3DNGH as the photocathode active material, replaces the expensive platinum electrode, introduces dual photosensitive electrodes, reduces the cost, and significantly improves the utilization rate of solar energy.

(3) The light-assisted bipolar self-powered aptamer sensor proposed by the present invention realizes the sensitive detection of SMZ. In the concentration range of 0.001-100ng/mL, the log value of SMZ concentration (lg C _SMZ ) is related to the self-powered The potential output (OCP) value of the sensing platform showed a good linear relationship, and the detection limit could reach 0.33pg/mL.

(4) The novel light-assisted bipolar self-powered aptamer sensor constructed by the present invention does not require an external power supply, and at the same time uses a multimeter as a direct readout strategy to replace the electrochemical workstation to collect data, which is easy to carry and can be operated outdoors, thereby achieving real-time detection effect.

Description of drawings

Figure 1 is a schematic diagram of the constructed light-assisted bipolar self-powered aptasensor;

Figure 2 is the transmission electron microscope images of prepared B-TiO ₂ and Cu ₂ O/3DNGH;

Fig. 3 (A) is the voltage-current curve (VI) relationship diagram of the self-powered platform that is made up of B-TiO2/ITO photoanode and different photocathodes in the step (3) of embodiment 1, (B) power density- Current curve (PI) relationship diagram, (C) digital photo of multimeter readout voltage and (D) open circuit potential value; among them, Pt(a), 3DNGH/ITO(b), Cu ₂ O/ITO(c), Cu ₂ O/3DNGH/ITO(d);.

Figure 4 (A), (B) is the digital photo of the multimeter readout voltage and the open circuit potential value of the self-powered sensing platform under different SMZ concentrations; (C) is the relationship between the SMZ concentration and the output potential of the self-powered sensing platform (The embedded graph is its linear relationship graph); (D) and (E) are the selectivity and stability test graphs of the sensor.

detailed description

The present invention is described in detail below in conjunction with examples, but the present invention is not limited to these examples.

Figure 1 is a schematic diagram of the constructed light-assisted bipolar self-powered aptasensor.

Example 1:

(1) Preparation of B- _TiO2

Measure 1.7mL of tetrabutyl titanate and 2.5mL of ethanol and mix them evenly to obtain solution A; measure and mix 0.1mL of concentrated nitric acid, 2.5mL of ethanol and 0.5mL of water to obtain solution B; Add dropwise into solution B, stir for 0.5h to obtain mixed solution C, transfer it to a stainless steel autoclave, and react at 180°C for 12h to obtain solid product titanium dioxide; weigh 200mg of titanium dioxide and 66.66mg of sodium borohydride and mix them in a mortar Grind sufficiently, transfer to a porcelain crucible, put into a tube furnace, and calcinate at 350°C for 1h in an argon atmosphere with a heating rate of 10°C/min to obtain B-TiO ₂ nanoparticles.

(2) Preparation of Cu ₂ O/3DNGH

First, 50 mL of graphene oxide dispersion (1 g/mL) was stirred with 2 g of urea, transferred to an autoclave, and reacted at 180 ° C for 12 h to obtain 3DNGH. Then, 0.25 g of copper nitrate was dissolved in 50 mL of water, and 4 mL of hydrazine hydrate solution (0.5 mol/L) was added dropwise under magnetic stirring. After fully reacting, it was centrifuged, washed, and dried in vacuum to obtain Cu ₂ O powder. Next, 0.1g Cu ₂ O was weighed, mixed with 10mL isopropanol and 0.1mL 3-aminopropyltrimethylsilane, stirred thoroughly for 24 hours, and washed by centrifugation to obtain positively charged surface functionalized Cu ₂ O. Finally, 50 mg of positively charged surface-functionalized Cu ₂ O and 10 mL of 3DNGH aqueous solution (1 g/mL) were weighed and stirred for 4 hours to obtain Cu ₂ O/3DNGH.

Fig. 2 is the transmission electron micrograph of B-TiO ₂ and Cu ₂ O/3DNGH obtained in Example 1, it can be seen that the prepared B-TiO ₂ is uniformly distributed 5-10nm nanoparticles; for Cu ₂ O/3DNGH Composite material, Cu ₂ O spheres with a diameter of about 500nm were coated with 3DNGH of wrinkled structure.

(3) Manufacture of modified electrodes

Before preparing the photoanode and photocathode, the ITO was pretreated. The ITO electrode was boiled in 1M sodium hydroxide solution for 30 minutes, then ultrasonically cleaned with acetone, distilled water and ethanol in sequence, and dried with nitrogen gas for later use. The cleaned ITO electrodes were packaged with polyimide tape ("gold finger"), and finally the geometric area of the ITO exposed was 0.09πcm ² . Weigh 2mg of B-TiO ₂ and Cu ₂ O/3DNGH and disperse in 1mL DMF respectively to obtain B-TiO ₂ , Cu ₂ O/3DNGH dispersion, pipette 20μL of B-TiO ₂ , Cu ₂ O/3DNGH dispersion respectively Evenly drop-coated on the ITO electrode, and dried under an infrared lamp to obtain a photoanode B-TiO ₂ /ITO and a photocathode Cu ₂ O/3DNGH/ITO.

The photoanode, different photocathodes Pt (a), _3DNGH /ITO (b), Cu2O/ITO (c), Cu2O/ _3DNGH /ITO (d) were placed in phosphate buffered solution (PBS) containing In the single-chamber electrolytic cell, the xenon lamp perpendicular to the two photoelectrodes irradiates the photoanode and photocathode at the same time, and the two electrodes are connected with a multimeter to directly collect the potential signal. Wherein, the concentration of PBS is 0.1 mol/L, pH=5.

In order to verify the accuracy of the collected signals, electrochemical analysis was carried out through the two-electrode system of the electrochemical workstation.

Figure 3 shows the self-powered platform composed of B-TiO2/ITO photoanode and different photocathodes (Pt(a), 3DNGH/ITO(b), Cu2O/ITO(c), Cu2O/3DNGH/ITO(d)). (A) Voltage-current curve (V-I) relationship diagram, (B) power density-current curve (P-I) relationship diagram, (C) digital photo of multimeter readout voltage and (D) open circuit potential value. It can be seen from Figure 3 that the self-powered platform composed of photoanode B-TiO2/ITO and photocathode Cu2O/3DNGH/ITO has the best electrical output performance; at the same time, the output potential value of the self-powered platform read directly by the multimeter is consistent with The potential values measured by the electrochemical workstation are consistent, which proves the accuracy of the data read by the multimeter.

(4) Construction of light-assisted bipolar self-powered aptamer sensor devices

First, 10 μL of 0.1% CHIT solution was drop-coated on the photoanode B-TiO ₂ /ITO, and dried under an infrared lamp. Next, 20 μL of 2.5% GA solution was dropped on the surface of the electrode, and left to react at room temperature for 1 h. After the reaction was completed, rinse twice with PBS (pH=5.0, 0.1 mol/L) to remove excess GA on the electrode surface. Use Tris-HCl (pH=7.4, 0.05mol/L) to prepare a SMZ aptamer solution with a concentration of 3 μM. The SMZ aptamer sequence is: 5′-NH ₂ -TTA GCT TAT GCG TTG GCC GGG ATAAGG ATC CAG CCG TTG TAG ATT TGC GTT CTA ACT CTC-3'. Add 20 μL of SMZ aptamer dropwise on the electrode, place it in a refrigerator at 4°C for 12 hours, rinse with PBS twice to remove excess unadsorbed aptamer, and then add 20 μL of 3% BSA solution dropwise to block non-specificity The active site is finally obtained by aptamer-modified photoanode (aptamer/B-TiO ₂ /ITO), and the photocathode Cu ₂ O/3DNGH/ITO constitutes a photo-assisted bipolar self-powered aptamer sensor device.

Light-assisted bipolar self-powered aptamer sensing device for detection of SMZ

Thereafter, 20 μL of SMZ with concentrations of 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 50 and 100 ng/mL were dropped onto the photoanode aptamer/B- _TiO2 /ITO electrode respectively, and incubated at room temperature Incubate for a period of time. Finally, put the photoanode aptamer/B-TiO ₂ /ITO and photocathode Cu ₂ O/3DNGH/ITO into a single-chamber electrolytic cell containing 20 mL of PBS (pH=5.0, 0.1 mol/L), and pass through the electrochemical workstation In the two-electrode system, the electrochemical analysis is carried out under the simultaneous vertical irradiation of two photoelectrodes by a xenon lamp light source (with an intensity of 25% to 100%).

The test results are shown in Figure 4:

Figure 4 (A) and (B) are the digital photos and open circuit potential values of the multimeter read voltage of the self-powered sensing platform under different SMZ concentrations. It can be seen from the figure that with the increase of the SMZ concentration, the multimeter reads The output potential of the self-powered sensing platform increases gradually; (C) is the relationship diagram between the SMZ concentration and the output potential of the self-powered sensing platform (the embedded figure is its linear relationship diagram), within the concentration range of 0.001-100ng/mL , there is a good linear relationship between the potential value and the concentration of SMZ, and the detection limit can reach 0.33pg/mL;

Example 2:

(1) Preparation of B-TiO ₂ nanoparticles

Measure 1mL of tetrabutyl titanate and 1.5mL of ethanol and mix them evenly to obtain solution A; measure and mix 0.05mL of concentrated nitric acid, 1.25mL of ethanol and 0.25mL of water to obtain solution B; Add to solution B, stir for 0.5h to obtain mixed solution C, transfer to a stainless steel autoclave, react at 180°C for 10h, and obtain solid product titanium dioxide; weigh 100mg of titanium dioxide and mix with 33.33mg of sodium borohydride, grind in a mortar fully, transferred to a porcelain crucible, placed in a tube furnace, and calcined at 300 °C for 1 h in an argon atmosphere with a heating rate of 10 °C/min to obtain B-TiO ₂ nanoparticles.

(2) Preparation of Cu ₂ O/3DNGH

First, 50 mL of graphene oxide dispersion (1 g/mL) was stirred with 2 g of urea, transferred to an autoclave, and reacted at 180 ° C for 12 h to obtain 3DNGH. Then, 0.25 g of copper nitrate was dissolved in 50 mL of water, and 4 mL of hydrazine hydrate solution (0.5 mol/L) was added dropwise under magnetic stirring. After fully reacting, it was centrifuged, washed, and dried in vacuum to obtain Cu ₂ O powder. Next, 0.1g Cu ₂ O was weighed, mixed with 10mL isopropanol and 0.1mL 3-aminopropyltrimethylsilane, stirred thoroughly for 12 hours, and washed by centrifugation to obtain positively charged surface functionalized Cu ₂ O. Finally, 25 mg of positively charged surface-functionalized Cu ₂ O and 5 mL of 3DNGH aqueous solution (1 g/mL) were weighed and stirred for 2 h to obtain Cu ₂ O/3DNGH.

Steps (3) and (4) are the same as those in Example 1 (3) and (4).

Example 3:

(1) Preparation of B-TiO ₂ nanoparticles

Measure 3mL of tetrabutyl titanate and 4mL of ethanol and mix them evenly to obtain solution A; measure and mix 0.15mL of concentrated nitric acid, 3.75mL of ethanol and 0.75mL of water to obtain solution B; add solution A dropwise into solution B, stirred for 0.5h to obtain mixed solution C, transferred to a stainless steel autoclave, and reacted at 180°C for 14h to obtain a solid product of titanium dioxide; weigh 300mg of titanium dioxide and 100mg of sodium borohydride, mix them in a mortar and grind them thoroughly, Transfer to a porcelain crucible, put it into a tube furnace, and calcinate at 400 °C for 1 h in an argon atmosphere with a heating rate of 10 °C/min to obtain B- _TiO2 nanoparticles.

(2) Preparation of Cu ₂ O/3DNGH

First, 50 mL of graphene oxide dispersion (1 g/mL) was stirred with 2 g of urea, transferred to an autoclave, and reacted at 180 ° C for 12 h to obtain 3DNGH. Then, 0.25 g of copper nitrate was dissolved in 50 mL of water, and 4 mL of hydrazine hydrate solution (0.5 mol/L) was added dropwise under magnetic stirring. After fully reacting, it was centrifuged, washed, and dried in vacuum to obtain Cu ₂ O powder. Next, 0.1g Cu ₂ O was weighed, mixed with 10mL isopropanol and 0.1mL 3-aminopropyltrimethylsilane, stirred thoroughly for 36 hours, and washed by centrifugation to obtain positively charged surface functionalized Cu ₂ O. Finally, 75 mg of positively charged surface-functionalized Cu ₂ O and 15 mL of 3DNGH aqueous solution (1 g/mL) were weighed and stirred for 6 h to obtain Cu ₂ O/3DNGH.

Steps (3) and (4) are the same as those in Example 1 (3) and (4).

Claims (10)

1. A construction method of a novel photo-assisted bipolar self-powered aptamer sensing device is characterized by comprising the following steps:

step 1, preparing photo-anode material black titanium dioxide B-TiO ₂ ：

Mixing tetrabutyl titanate with ethanol to obtain a solution A;

mixing concentrated nitric acid, ethanol and water to obtain a solution B;

dropwise adding the solution A into the solution B, uniformly stirring to obtain a mixed solution C, transferring the mixed solution C into a stainless steel high-pressure kettle to perform solvothermal reaction, and obtaining a solid product titanium dioxide after the reaction is finished; fully grinding the obtained titanium dioxide and sodium borohydride in a mortar, transferring the ground titanium dioxide and sodium borohydride to a ceramic crucible, calcining and reducing the ground titanium dioxide and the sodium borohydride in a tubular furnace under the argon atmosphere, and obtaining a solid product, namely B-TiO after the reaction is finished ₂ ；

Step 2, preparing a photocathode material three-dimensional nitrogen-doped graphene hydrogel loaded cuprous oxide nanosphere Cu ₂ O/3DNGH：

Firstly, stirring graphene oxide dispersion liquid and urea, transferring the graphene oxide dispersion liquid and the urea into an autoclave for solvothermal reaction, and obtaining 3DNGH after the reaction is finished;

then dissolving copper nitrate in water, dripping hydrazine hydrate solution under magnetic stirring, fully reacting, centrifugally washing, and vacuum drying to obtain Cu ₂ O powder;

finally, the obtained Cu ₂ Mixing O with isopropanol and 3-aminopropyl trimethyl silane, stirring uniformly, and centrifugally washing to obtain the surface functionalized Cu with positive charges ₂ O and then fully stirring with 3DNGH aqueous solution, thereby preparing a solid product Cu ₂ O/3DNGH；

Step 3, manufacturing of the modified electrode:

the B-TiO obtained in the step 1 and the step 2 ₂ And Cu ₂ O/3DNGH is dispersed in N, N-dimethylformamide DMF to respectively obtain B-TiO ₂ Dispersion liquid, cu ₂ O/3DNGH Dispersion of B-TiO ₂ 、Cu ₂ Respectively dripping O/3DNGH dispersion liquid on ITO electrodes with fixed areas, placing the ITO electrodes under an infrared lamp for drying to obtain B-TiO ₂ ITO electrode as photo-anode, cu ₂ An O/3DNGH/ITO electrode is used as a photocathode;

step 4, constructing a light-assisted bipolar self-powered adapter sensing device for detecting SMZ:

firstly, at the photo-anode B-TiO ₂ Dripping chitosan CHIT solution on the ITO, and drying under an infrared lamp;

dripping a glutaraldehyde GA solution on the surface of the electrode, placing the electrode at room temperature for reaction, leaching the electrode with PBS after the reaction is finished, and removing redundant GA on the surface of the electrode;

preparing an SMZ aptamer solution by using Tris-HCl as a solvent, dropwise adding the SMZ aptamer on an electrode, after reacting for a period of time, leaching by using PBS to remove excessive unadsorbed aptamer, then dropwise adding bovine serum albumin BSA solution to seal nonspecific active sites, and finally obtaining the photoanode aptamer/B-TiO modified by the aptamer ₂ ITO, and photocathode Cu ₂ O/3DNGH/ITO constitutes the photo-assisted bipolar self-powered aptamer sensing device.

2. The method of claim 1, wherein, in step 1,

in the solution A, the dosage ratio of tetrabutyl titanate to ethanol is 1-3 mL:0.05 to 5mL;

in the solution B, the dosage ratio of concentrated nitric acid, ethanol and water is 0.05-0.15 mL: 0.05-5 mL: 0.1-1 mL;

when the solution A and the solution B are mixed, the ratio of tetrabutyl titanate to concentrated nitric acid is 1-3 mL: 0.05-0.15 mL.

3. The construction method according to claim 1, wherein in the step 1, the temperature of the solvothermal reaction is 160-200 ℃, and the reaction time is 10-14 h; the mass ratio of titanium dioxide to sodium borohydride is 3:1; the calcination temperature is 300-400 ℃, the calcination time is 0.5-1.5 h, and the heating rate is 10 ℃/min.

4. The method of claim 1, wherein in step 2,

the dosage proportion of the graphene oxide dispersion liquid to the urea is 50mL:2g, wherein the concentration of the graphene oxide dispersion liquid is 1g/mL; the temperature of the solvothermal reaction is 150 ℃, and the reaction time is 10h;

the dosage ratio of the copper nitrate, water and hydrazine hydrate solution is 0.25g:50mL of: 4mL; wherein the concentration of the hydrazine hydrate solution is 0.5mol/L;

Cu ₂ the dosage proportion of O, isopropanol and 3-aminopropyltrimethylsilane is 0.1g:10mL of: 0.1mL, and the stirring time is 12-36 h;

resulting positively charged surface functionalized Cu ₂ The dosage ratio of the O to the 3DNGH aqueous solution is 25-75 mg:5 to 15mL, wherein the concentration of the 3DNGH aqueous solution is 1g/mL, and the stirring time is 2 to 6 hours.

5. The method of claim 1, wherein in step 3, B-TiO ₂ Dispersion liquid, cu ₂ The concentration of the O/3DNGH dispersion liquid is 1-3mg/mL; B-TiO2 ₂ 、Cu ₂ The dripping amount of the O/3DNGH dispersion liquid is 20-40 mu L, and the fixed area of the ITO is 0.09 pi cm ² 。

6. The method of claim 1, wherein, in step 4,

the mass percentage concentration of the CHIT is 0.1 percent, and the dropping amount is 10 mu L;

the volume percentage concentration of the GA is 2.5 percent, and the dropping amount is 20 mu L; the reaction time of CHIT and GA is 1-2 h.

7. The method of claim 1, wherein, in step 4,

the SMZ aptamer sequence was: 5' -NH ₂ -TTA GCT TAT GCG TTG GCC GGG ATA AGG ATC CAG CCG TTG TAG ATT TGC GTT CTA ACT CTC-3'; the concentration of the SMZ aptamer is 3 mu M, the dropping amount is 20-40 mu L, and the reaction time is 10-14 h; the mass percentage concentration of BSA is 3%.

8. Use of a photo-assisted bipolar self-energized aptamer sensor device constructed according to the construction method of any one of claims 1 to 7 for detecting sulfadimidine SMZ.

9. The use according to claim 8, characterized by the specific steps of:

(1) Dropping SMZ solutions of different concentrations to aptamer/B-TiO ₂ ITO photo anode and incubating for a period of time at room temperature;

(2) Photo-anode and photo-cathode Cu treated in the step (1) ₂ Placing O/3DNGH/ITO into a single-chamber electrolytic cell containing PBS, vertically irradiating two photoelectrodes by a xenon lamp light source simultaneously, connecting the two photoelectrodes by using a universal meter, and directly collecting a potential signal; making a standard curve of the logarithm value of the potential value and the concentration of SMZ;

(3) And collecting potential signals of the SMZ solution with unknown concentration by adopting the method, and substituting the potential signals into the standard curve to obtain the concentration of the SMZ solution.

10. The use according to claim 9,

in the step (1), the concentration of SMZ is 0.001-100100 ng/mL, and the dripping amount is 10-30 mu L;

in the step (2), the amount of PBS is 20-30 mL; the intensity of the xenon lamp light source is 25-100%.

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