A light-assisted water-voluntary self-powered sensor for detecting microcystins and a preparation method and application thereof

Abstract

The application belongs to the field of electrochemical detection, and particularly relates to a light-assisted water-voltaic self-powered sensor for microcystin detection and a preparation method thereof. A glass substrate is used as a substrate, a copper foil tape is used as a positive electrode and a negative electrode, a Zr-MOF / PEDOT composite material is used as a power generation material to prepare a water-voltaic generator, and an MC-RR aptamer is assembled to construct a water-voltaic self-powered sensor. The water-voltaic self-powered sensor of the application significantly improves the generated electric output under light assistance. A capacitor is combined into the water-voltaic self-powered sensor, and the capacitor significantly amplifies the generated electric output through a charging-discharging process within dozens of seconds to several minutes. The application widens the application of Zr-MOF and PEDOT in water evaporation-induced power generation, and provides a new strategy for electrochemical detection. The constructed light-assisted water-voltaic self-powered sensor has a wide detection range, high sensitivity, low detection limit and detection cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrochemical detection, and particularly relates to a light-assisted water-voltaic self-powered sensor for microcystin detection and a preparation method thereof, more particularly to a Zr-MOF / PEDOT composite material as a base material, an aptamer (apta) with specific recognition as a recognition unit, which are co-modified on the surface of a functional glass material, and the apta / Zr-MOF / PEDOT / glass forms a light-assisted water-voltaic self-powered sensor, and an electrochemical analysis method for quantitatively detecting microcystin MC-RR in wastewater. BACKGROUND

[0002] Due to climate change and water eutrophication, toxic cyanobacterial (blue-green algae) blooms are increasing worldwide, and the microcystins (MCs) produced by cyanobacteria pose a great threat to public health. By specifically binding to protein phosphatase 1 and 2A in the liver, MCs inhibit the function of these two key enzymes in cell regulation, so long-term accumulation in the human body can lead to a high incidence of primary liver cancer. Among the various isomers of MCs, MC-RR is currently of great concern due to its toxicity and frequent occurrence. Therefore, it is particularly important to rapidly detect MCs in necessities such as fish, shellfish, vegetables, and algal dietary supplements for human health. Current methods for detecting MC-RR include liquid chromatography, protein phosphatase inhibition tests, and capillary electrophoresis. However, these methods are limited by many factors, such as a complicated detection process, time-consuming and complex sample pretreatment, and expensive equipment. Therefore, there is an urgent need to develop a rapid, accurate, and cost-effective method.

[0003] Hydroelectric photovoltaic sensors can generate electricity directly through the interaction of nanostructured materials with water, and thus have the characteristics of sustainability, spontaneity, ubiquity, and no pollution. It is an environmentally friendly and emission-free strategy that can generate electricity without light. Light assistance can increase the current response, making the sensor reaction more sensitive. Metal-organic frameworks (MOFs) are a new type of porous crystalline material constructed by alternating inorganic secondary building units and organic linkers. The high surface area, ideal porosity, and good stability of Zr-MOFs are beneficial to the construction of water-voltaic sensors. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a well-known conductive polymer that can accelerate electron transfer and enhance conductivity due to its high conductivity and stable electrical properties. Currently, there is no report on the construction of light-assisted water-voltaic power generation devices using Zr-MOF and PEDOT. SUMMARY

[0004] The present application aims to provide a light-assisted water-voltaic self-powered sensor and a preparation method and application thereof. The sensor has a simple preparation process, low cost, and high sensitivity, and achieves the purpose of rapid quantitative detection of MC-RR.

[0005] One of the purposes of the present application is to provide a light-assisted water-driven self-powered sensor, which comprises Zr-MOF / PEDOT composite material as power generation material, and aptamer (apta) with specific recognition as recognition unit, which are collectively modified on the functional glass material coating surface to form apta / Zr-MOF / PEDOT / glass light-assisted water-driven self-powered sensor.

[0006] The second purpose of the present application is to provide a preparation method of the above-mentioned light-assisted water-driven self-powered sensor, and the specific steps are as follows:

[0007] (1) Preparation of Zr-MOF / PEDOT composite material:

[0008] Zr-MOF and PEDOT are uniformly dispersed in a suspension prepared by mixing anhydrous ethanol and deionized water in a volume ratio of 1:1 to obtain a uniform Zr-MOF / PEDOT composite material suspension.

[0009] (2) Construction of water-driven cell:

[0010] The glass substrate is cleaned in acetone, ethanol and ultrapure water for 30 min respectively. The glass is used as the substrate, and the copper foil tape is used as the electrode to stick the upper electrode in the shape of "1" and the lower electrode in the shape of "L". The Zr-MOF / PEDOT composite material suspension is added between the upper and lower electrodes by using a pipette gun to make it evenly spread between the two electrodes. Finally, the prepared device is dried in a 60 ℃ vacuum drying oven.

[0011] (3) Preparation of sensor

[0012] A certain concentration of MC-RR aptamer is added to the surface of the water-driven cell power generation material prepared in step (2). After natural drying at room temperature, a light-assisted water-driven self-powered aptamer sensor with selective recognition for MC-RR is obtained.

[0013] Zr-MOF is prepared by adding 5, 10, 15, 20-tetrahydro (4-carboxyphenyl) porphyrin (H2TCPP), zirconium chloride (ZrCl4) and benzoic acid (BA) into N, N-dimethylformamide (DMF). Then, H2O is added as a regulator to prepare a dark green solution. The obtained solution is transferred to a polytetrafluoroethylene liner and subjected to hydrothermal reaction in an oven at a temperature of 100-140 ℃ for 20-28 h. After cooling to room temperature, the obtained precipitate is washed with DMF and filtered, and then soaked in ethanol for 2 days. During this period, the solvent is exchanged and refreshed every 6 hours. Finally, the precipitate is filtered and dried in vacuum to obtain purple crystals. The mass ratio of the amount of H2TCPP, ZrCl4 and BA is 2-3:3-4:125-145.

[0014] The PEDOT is prepared by the following method: 3,4-ethylenedioxythiophene (EDOT) is slowly dispersed in an ammonium persulfate aqueous solution, stirring is continuously performed for 2-3 days, centrifugation is performed to obtain a black crude product, washing is performed, and vacuum freeze drying is performed to obtain the PEDOT. The mass ratio of the EDOT and the ammonium persulfate is 18-22:140-143.

[0015] As one of the preferred technical solutions of the preparation method of the above-mentioned photo-assisted water plume self-powered sensor, in the step (1), the concentration of the composite material suspension is 10 mg / ml, and ultrasonic dispersion is performed for 4-8 h.

[0016] As one of the preferred technical solutions of the preparation method of the above-mentioned photo-assisted water plume self-powered sensor, in the step (1), in the Zr-MOF / PEDOT, the mass percentage of the Zr-MOF is 40-50%.

[0017] As one of the preferred technical solutions of the preparation method of the above-mentioned photo-assisted water plume self-powered sensor, in the step (2), the drop coating amount is 60-100 μL / cm 2 In some specific embodiments of the present application, the drop coating area is 2.0*3.0 cm 2 , and the coating amount is 400-600 μL.

[0018] As one of the preferred technical solutions of the preparation method of the above-mentioned photo-assisted water plume self-powered sensor, in the step (3), the concentration of the MC-RR aptamer is 1 μM, and the drop amount is 3-4 μL / cm 2 .

[0019] The application of the self-powered sensor in photoelectrochemical detection of MC-RR, and the specific sequence of the nucleotide of the MC-RR aptamer is as follows:

[0020] The aptamer is 5'-CAG CTC AGA AGC TTG ATC CTA CTG CCC TTC AAT GTT CAC TCC TGTTTC CTG ATC TTT GTC GAC TCG AAG TCG TGC ATC TG-3'.

[0021] The third object of the present application is to provide the application of the above-mentioned photo-assisted water plume self-powered sensor in detection of microcystin (MC-RR).

[0022] The specific detection method comprises the following steps:

[0023] S1, preparing microcystin MC-RR with different concentrations;

[0024] Accurately weigh a certain amount of MC-RR, dilute it with deionized water step by step, and obtain a series of different concentrations of microcystin standard solution, with a concentration range of 1.0 x 10 -11 mol / L~1.0 x 10 -8 mol / L;

[0025] S2, drawing of standard curve:

[0026] Select a series of MC-RR standard solutions with known concentrations and drop them on the surface of the prepared water-activated battery power generation material, and dry naturally at room temperature;

[0027] Take the copper foil tape upper and lower electrodes as the positive and negative electrodes of the electrochemical test, take the Zr-MOF / PEDOT composite material as the power generation material, assemble the MC-RR aptamer, and form a water-activated self-powered system, take deionized water as the electrolyte, control the xenon lamp light source current to be 20 A, the horizontal distance from the light source outlet to the glass substrate is 12 cm, measure the instantaneous current of 100 s under the test potential of 0 V, obtain a series of concentration-short circuit current corresponding relationships, and then obtain the standard curve of MC-RR, establish the linear relationship between the short circuit current intensity after adding MC-RR and the logarithmic value of the concentration of MC-RR, and obtain the corresponding linear regression equation.

[0028] S3, actual sample detection:

[0029] The actual sample is pretreated before detection, and then the pH value is adjusted, and the linear regression equation in step S2 is calculated.

[0030] As preferred: in step S3, the incubation reaction time of the light-activated water-activated self-powered sensor is 20 min.

[0031] The minimum detection limit of the MC-RR solution concentration detected by the sensor is 1.01 x 10 -12 M.

[0032] Compared with the prior art, the light-activated water-activated self-powered aptamer sensor has the following beneficial effects:

[0033] (1) The Zr-MOF / PEDOT composite material is used as the power generation material to prepare the water-activated device. The ordinary glass is used as the substrate material, Zr-MOF is a new type of crystalline porous material, which has good water-activated characteristics, such as high porosity, high surface area, and is supplemented with PEDOT to enhance the photoelectric response and ion transmission, and is used as a local heater to enhance the carrier separation and accelerate the reaction kinetics. In the preparation of the light-activated water-activated self-powered sensor, the light assistance significantly improves the current signal, and the addition of the aptamer enables the sensor to specifically detect MC-RR.

[0034] (2) Compared with traditional detection methods, the water-voltaic electrochemical detection method proposed in this invention has the characteristics of simple and flexible operation, simple instruments and equipment, high sensitivity, wide linear range, low detection limit and low detection cost. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings and examples.

[0036] Figure 1 This is a schematic diagram illustrating the fabrication of the sensor and the detection of MC-RR in this invention.

[0037] Figure 2 These are current signals measured from batteries with different proportions of composite materials added.

[0038] Figure 3 This is a comparison chart showing the Zr-MOF / PEDOT composite material before and after using a capacitor to amplify the current signal.

[0039] Figure 4 This is a short-circuit current diagram of a self-powered sensor with different concentrations of MC-RR added in Example 2.

[0040] Figure 5 This is a standard curve of the short-circuit current after adding MC-RR in Example 2 versus the logarithm of MC-RR concentration. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the embodiments.

[0042] like Figure 1 As shown, a method for preparing a photovoltaic self-powered sensor and its application in MC-RR detection is described. A photovoltaic generator is prepared using Zr-MOF / PEDOT composite material as the power generation material to form a self-powered system. An MC-RR aptamer is then assembled to achieve specific detection of MC-RR. Example 1

[0043] The effects of Zr-MOF / PEDOT composite materials with different mass ratios on the water-volt performance of sensors were compared.

[0044] (1) Preparation of Zr-MOF;

[0045] Add 50 mg of 5,10,15,20-tetrahydro(4-carboxyphenyl)porphyrin (H2TCPP), 70 mg of zirconium chloride (ZrCl4) and 2700 mg of benzoic acid (BA) into 8 mL of N,N-dimethylformamide (DMF). Then, add 1000 μL of H2O as a regulator to make a dark green solution. Transfer the resulting solution into a 25 ml Pyrex vial and heat in an oven at 120 °C for 24 hours. After cooling to room temperature, wash the resulting precipitate with DMF and filter three times, then immerse in ethanol for 2 days. During this period, change the solvent every 6 hours. Finally, filter the precipitate, heat in vacuum at 80 °C for 12 h, then get purple crystals.

[0046] (2) Preparation of PEDOT;

[0047] Slowly disperse 0.203 g of 3,4-ethyl-ethylenedioxythiophene (EDOT) in 20 mL of aqueous ammonium persulfate solution (0.31 M) and keep stirring for 3 days; centrifuge to get black crude product. Then wash with ultrapure water to remove excess oxidant, then use methanol (20 mL) and acetone (3 mL) to remove unreacted oligomers and monomers, and dry in a vacuum freeze dryer.

[0048] (3) Preparation of Zr-MOF / PEDOT composite materials with different proportions:

[0049] Prepare water-voltaic cells with Zr-MOF / PEDOT composite materials with different proportions, respectively (3:1, 3:2, 1:1, 2:3, 1:3), the specific amount of Zr-MOF: PEDOT in 2 ml of solvent (volume ratio of 1:1 of anhydrous ethanol and deionized water) is respectively: 15 mg:5 mg, 12 mg:8 mg, 10 mg:10 mg, 8 mg:12 mg, 5 mg:15 mg, ultrasonic dispersion for 5 hours to get uniform Zr-MOF / PEDOT composite material suspension, the suspension concentration is 10 mg / mL.

[0050] (4) Construction of water-voltaic cell:

[0051] Clean the glass substrate in acetone, ethanol and ultrapure water for 30 min respectively. With glass as the substrate, copper foil tape as the electrode, paste the upper electrode as "one" and the lower electrode as "L". Use a pipette to drop Zr-MOF / PEDOT composite suspension material between the upper and lower electrodes, so that it evenly covers between the two electrodes (about 2x3 cm). Finally, put the prepared device in a 60°C vacuum drying oven for drying.

[0052] Water-activated performance test: the copper foil tape upper and lower electrode as the positive and negative electrode of electrochemical test, Zr-MOF / PEDOT composite material as power generation material, to form water-activated self-powered system, deionized water as electrolyte, control xenon lamp light source current to 20 A, the horizontal distance from light source outlet to glass substrate is 12 cm, the short circuit current response value is measured at 0 V test potential.

[0053] By Figure 2 It can be seen that with the increase of the proportion of PEDOT, the short circuit current continues to increase. When the mass ratio of Zr-MOF / PEDOT is 1:1, the short circuit current is the largest. Therefore, the best ratio of Zr-MOF / PEDOT composite material is 1:1.

[0054] Figure 3 Zr-MOF / PEDOT (1:1) composite material before and after using capacitor to amplify current signal. The water-activated performance after capacitor amplification is the instantaneous current measured after charging for 100 s under the same conditions. It can be seen that the water-activated performance after amplification is stronger, which can effectively improve the sensitivity of the constructed sensor. Example 2

[0055] A method for constructing a light-assisted water-activated self-powered sensor and its application in detecting microcystin has the following steps:

[0056] (1) Preparation of Zr-MOF; same as example 1.

[0057] (2) Preparation of PEDOT; same as example 1.

[0058] (3) Preparation of Zr-MOF / PEDOT composite material:

[0059] 20 mg of Zr-MOF and 20 mg of PEDOT were added to a 5 ml centrifuge tube, 10 mg / mL suspension was prepared by adding anhydrous ethanol and deionized water with a volume ratio of 1:1, ultrasonic dispersion for 5 hours, and a uniform Zr-MOF / PEDOT composite suspension material was obtained.

[0060] (4) Construction of water-activated cell:

[0061] The glass substrate was cleaned in acetone, ethanol and ultrapure water for 30 min respectively. With glass as substrate, copper foil tape as electrode, the upper electrode of "one" and the lower electrode of "L" shape were pasted. Zr-MOF / PEDOT composite suspension material was added between the upper and lower electrodes by pipette gun, so that it was evenly spread between the two electrodes (about 2*3 cm). Finally, the prepared device was dried in a 60℃ vacuum drying oven.

[0062] (5) Preparation of sensor

[0063] 20 μL of MC-RR aptamer at a concentration of 1 μM was dropped onto the surface of the water-voltaic battery power generation material prepared in step (4). After natural drying at room temperature, an aptamer sensor with selective recognition of MC-RR was obtained.

[0064] The aptamer sequence of the above sensor is as follows: aptamer: 5'-CAG CTC AGA AGC TTG ATC CTACTG CCC TTC AAT GTT CAC TCC TGT TTC CTG ATC TTT GTC GAC TCG AAG TCG TGC ATCTG-3'.

[0065] (6) Plotting the standard curve:

[0066] Preparation of MC-RR standard solutions: Dissolve MC-RR in 10 ml of deionized water, and then dilute stepwise with deionized water to obtain a series of MC-RR standard solutions of different concentrations;

[0067] In a photovoltaic self-powered sensor based on light assistance, copper foil tape upper and lower electrodes are used as the positive and negative electrodes for electrochemical testing, Zr-MOF / PEDOT composite material is used as the power generation material, and an MC-RR aptamer is assembled to form a photovoltaic self-powered system. The self-powered aptamer sensor has an incubation time of 20 min, uses deionized water as the electrolyte, controls the xenon lamp light source current to be 20 A, and the horizontal distance from the light source outlet to the glass substrate is 12 cm. The instantaneous current during charging for 100 s is measured at a test potential of 0 V. Figure 4 As shown, the concentrations of MC-RR, arranged from top to bottom according to the peak value of the curve (a→g), are: 1.0×10⁻⁶ -11 mol / L, 5.0×10 -10 mol / L, 1.0×10 -10 mol / L, 5.0×10 -9 mol / L, 1.0×10 -9 mol / L, 5.0×10 -8 mol / L, 1.0×10 -8 mol / L.

[0068] Electrodes modified with different concentrations of MC-RR were used as working electrodes, where the concentrations of MC-RR were (1.0 × 10⁻⁶) and (1.0 × 10⁻⁶) respectively. -11 mol / L, 5.0×10 -10 mol / L, 1.0×10 -10 mol / L, 5.0×10 -9 mol / L, 1.0×10 -9mol / L, 5.0×10 -8 mol / L, 1.0×10 -8 Using deionized water as the electrolyte, a xenon lamp source current of 20 A was selected, and the horizontal distance from the light source outlet to the glass substrate was 12 cm. The power response value was measured at a test potential of 0 V. Then, the following was obtained: Figure 5 The linear relationship between the logarithm of MC-RR concentration and the magnitude of short-circuit current is shown, with a correlation coefficient (R) of 0.97858. The detection range of the linear regression equation is 1.0 × 10⁻⁶. -11 -1.0×10 -8 mol / L, with a detection limit of 1.01 × 10⁻⁶. -12 mol / L.

[0069] (7) Sample detection

[0070] A certain amount of wastewater after removing impurities was used to prepare an MC-RR solution for photoelectrochemical detection. The concentration of MC-RR in the sample was calculated according to the regression equation corresponding to step (6) above. The results are listed in Table 1.

[0071] Table 1. Determination results of MC-RR in water samples

[0072] .

[0073] As shown in Table 1, the samples were tested in parallel three times, with a relative standard deviation of less than 5% and a spiked recovery rate ranging from 94% to 102%. This invention can be used to detect MC-RR in wastewater.

[0074] The preferred embodiments of the present invention described above are for illustrative purposes. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical spirit of the present invention. The technical scope of the present invention is not limited to the contents of the specification.

Claims

1. A light assisted waterborne self-powered sensor for MC-RR detection, characterized in that, The light-assisted water-voltaic self-powered sensor comprises Zr-MOF / PEDOT composite material as a power generation material, and an aptamer with specific recognition as a recognition unit, which are collectively modified on the surface of functional glass to form the apta / Zr-MOF / PEDOT / glass substrate light-assisted water-voltaic self-powered sensor.

2. A method for the preparation of a photo-assisted waterborne self-powered sensor for MC-RR detection as claimed in claim 1, characterized by, The preparation steps include the following steps: In step (1), the Zr-MOF / PEDOT composite material is uniformly dispersed in deionized water and anhydrous ethanol in a volume ratio of 1:1 to obtain a uniformly dispersed Zr-MOF / PEDOT composite material suspension; the concentration of the Zr-MOF / PEDOT composite material in the suspension is 10 mg / ml. In step (2), a pre-cleaned glass is used as a substrate, a copper foil tape is used as an electrode, and the "1" upper electrode and the "L" shaped lower electrode are pasted, and the Zr-MOF / PEDOT composite material suspension is dropped and coated between the upper and lower electrodes to make it evenly spread between the two electrodes, and then dried to obtain a light-assisted water-voltaic cell. In step (3), the MC-RR aptamer is added dropwise on the surface of the power generation material of the water-voltaic cell prepared in step (2), and naturally dried at room temperature to obtain a light-assisted water-voltaic self-powered sensor for MC-RR detection; the sequence of the MC-RR aptamer is: 5'-CAG CTC AGA AGC TTG ATC CTA CTG CCC TTC AAT GTT CAC TCC TGT TTC CTG ATC TTT GTC GAC TCG AAG TCG TGC ATC TG-3'.

3. The method for the preparation of photo-assisted water-volte self-powered sensor for MC-RR detection according to claim 2, characterized in that, In step (1), the mass percentage of Zr-MOF in the Zr-MOF / PEDOT composite material is 40-50%.

4. The method for preparing the photo-assisted water-volatage self-powered sensor for MC-RR detection according to claim 2, wherein, In step (2), the drop-casting amount of the Zr-MOF / PEDOT composite suspension is 60-100 μL / cm 2 .

5. The method for preparing the photo-assisted water-volatage self-powered sensor for MC-RR detection according to claim 2, wherein, In step (3), the concentration of MC-RR aptamer was 1 μmol / L, and the dropwise addition amount was 3-4 μL / cm 2 .

6. The method for preparing the photo-assisted water-volatage self-powered sensor for MC-RR detection according to claim 2, wherein, In step (1), the Zr-MOF is prepared by adding 5,10,15,20-tetrahydro(4-carboxyphenyl) porphyrin, zirconium tetrachloride and benzoic acid into N,N-dimethylformamide; adding H2O as a regulator to prepare a solution; hydrothermal reaction of the obtained solution at 100-140℃ for 20-28 hours; after cooling to room temperature, collecting the precipitate, washing, filtering, solvent exchange and drying to obtain the Zr-MOF; wherein the mass ratio of 5,10,15,20-tetrahydro(4-carboxyphenyl) porphyrin, zirconium tetrachloride and benzoic acid is 2-3:3-4:125-145.

7. The method for preparing the photo-assisted water-volte self-powered sensor for MC-RR detection according to claim 2, wherein, In step (1), the PEDOT is prepared by slowly dispersing 3,4-ethyl enedi oxthiophene in an aqueous solution of ammonium persulfate, continuously stirring for 2-3 days, centrifuging, washing, and vacuum freeze-drying to obtain the PEDOT; wherein the mass ratio of 3,4-ethyl enedi oxthiophene and ammonium persulfate is 18-22:140-143.

8. Use of the optically assisted waterborne self-powered sensor for MC-RR detection according to claim 1, characterized in that, Deionized water is used as an electrolyte, the current of the xenon lamp light source is controlled to be 20 A, the horizontal distance from the light source outlet to the glass substrate is 12 cm, and the short-circuit current intensity of the light-assisted water-voltaic self-powered sensor before and after the combination of the sample to be detected is measured at a test potential of 0 V for 100 s of charging, and the concentration of MC-RR in the sample to be detected is calculated according to the linear regression equation of the standard curve.

9. Use of a photo-assisted water volute self-powered sensor for MC-RR detection according to claim 8, characterized in that, The binding time of the sample to be tested and the aptamer is 10-60 min. The binding time of the sample to be tested and the aptamer is 10 10. The use of a light-aided water-volatilization self-powered sensor for MC-RR detection according to claim 8, wherein, The minimum detection limit of the detected MC-RR solution concentration is 1.01 x 10 -12 -3 mol / L.

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