A method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A

Abstract

The invention discloses a method for constructing a sensor for detecting bisphenol A by cathodic photoelectrochemistry, comprising the following steps: (1) preparation of BiOCl nanomaterials; (2) preparation of BiOCl / ITO electrodes; (3) preparation of biological reaction solutions of different concentrations of bisphenol A; (4) determination of photocurrent; (5) construction of a linear model. The invention utilizes that K4[Fe(CN)6] can combine with BiOCl nanosheets to generate a photoactive Prussian blue analogue (PBAs), constructs a cathodic photoelectrochemical detection method for in-situ generating a p-n heterojunction, and combines the rolling circle amplification technology (RCA) to realize the ultrasensitive detection of bisphenol A.

Description

Technical Field

[0001] The present invention relates to the technical field of food detection, and in particular to a method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A. Background Art

[0002] Bisphenol A (BPA) is widely used in the preparation of food packaging and baby bottles [Rubin, B. S. J. Steroid Biochem. Mol. Biol. 2011, 127, 27 - 34]. As an endocrine disruptor, it can disrupt the regulatory functions of the human body [Wang, Y.; Zhao, X. D.; Huo, B. Y.; Ren, S. Y.; Bai, J. L.; Peng, Y.; Li, S.; Han, D. P.; Wang, J.; Han, T.; Gao, Z. X. ACS Appl. Bio Mater. 2021, 4, 763 - 769], induce metabolic disorders [Alonso - Magdalena, P.; Ropero, A. B.; Soriano, S.; García - Arévalo, M.; Ripoll, C.; Fuentes, E.; Quesada, I,; Nadal, Mol. Cell. Endocrinol. 2012, 355, 201 - 207], cardiovascular diseases [Miao, M. H.; Yuan, W.; Zhu, G. P.; He, X. F.; Li, D. K. Reprod. Toxicol. 2011, 32, 64 - 68], and even malignant tumors [Soto, A. M.; Sonnenschein, C. Nat. Rev. Endocrinol. 2010, 6, 363 - 370], posing a serious threat to life and health. EU legislation stipulates that the maximum residue limit of bisphenol A in food or food packaging is 0.6 μg / g [EU (European Union). Off. J. Eur. Communities 2004, L71, 8 - 21]. Therefore, monitoring the content of bisphenol A is crucial for protecting human health.

[0003] The conventional detection methods of bisphenol A mainly include chromatography and fluorescence immunoassay. Among them, high performance liquid chromatography [Liu, Z.; Li, Y.; Sun, L.; Yang, H.; Zheng, X.; Wang, L. Biomed. Chromatogr. 2019, 33, 4419 - 4424], liquid chromatography - mass spectrometry [Park, J. S.; Yoon, Y. M.; Her, N. G. J. Korean Soc. Environ. Eng. 2010, 32, 639 - 648] and gas chromatography - mass spectrometry [Correia - Sá, L.; Norberto, S.; Delerue - Matos, C.; Calhau, C.; Domingues, V. F. J. Chromatogr. B 2018, 1072, 9 - 16] technologies have high specificity, but the equipment is expensive and the sample preparation process is relatively complex. For the fluorescence immunoassay technology [Du, L.; Zhang, C.; Wang, L.; Liu, G.; Zhang, Y.; Wang, S. Microchim. Acta 2015, 182, 539 - 545], its selectivity is relatively good, but the preparation process is time - consuming and complex, with certain limitations. Therefore, it is particularly necessary to design a method with simple operation and high sensitivity for the detection of bisphenol A.

[0004] Photoelectrochemical (PEC) biosensors have the characteristics of good selectivity, high sensitivity, low background signal and simple equipment, and have good development prospects [Shu, J.; Tang, D. Anal. Chem. 2020, 92, 363 - 377]. Comparatively speaking, the cathodic PEC biosensor has stronger anti - interference ability than the anodic PEC biosensor [Xu, Y. T.; Yu, S. Y.; Zhu, Y. C.; Fan, G. C.; Han, D. M.; Qu, P.; Zhao, W. W. Trends Anal. Chem. 2019, 114, 81 - 88]. However, the current cathodic PEC biosensors mainly achieve detection by using electron acceptors to capture photo - generated electrons to promote the improvement of carrier separation efficiency [Wang, G. L.; Shu, J. X.; Dong, Y. M.; Wu, X. M.; Zhao, W. W.; Xu, J. J.; Chen, H. Y. Anal. Chem. 2015, 87, 2892 - 2900], and the detection mode is relatively single. In addition, the photoelectrochemical cathode sensor has not been well applied to the detection of bisphenol A. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A. The present invention utilizes K4[Fe(CN)6] to combine with BiOCl nanosheets to generate a photoelectrochemically active Prussian blue analogue (PBAs), constructs a cathodic photoelectrochemical detection method for in-situ generating a p-n heterojunction, and combines the rolling circle amplification technology (RCA) to achieve ultrasensitive detection of bisphenol A.

[0006] The technical solution of the present invention is as follows:

[0007] The first object of the present invention is to provide a method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A, and the construction method includes the following steps:

[0008] (1) Preparation of BiOCl nanomaterials:

[0009] Dissolve Bi(NO3)3·5H2O in deionized water, then adjust the pH and perform a hydrothermal reaction to obtain BiOCl nanomaterials;

[0010] (2) Preparation of BiOCl / ITO electrode:

[0011] Disperse the BiOCl nanomaterials prepared in step (1) in deionized water to form a suspension; then drop the obtained suspension onto the surface of the ITO electrode and dry it to obtain the BiOCl / ITO electrode;

[0012] (3) Preparation of biological reaction solutions of different concentrations of bisphenol A:

[0013] ① Mix different concentrations of bisphenol A, bisphenol A aptamer and Tris–HCl buffer solution and incubate;

[0014] ② Add a padlock probe and T4 DNA ligase, and perform a ligation reaction in a Tris–HCl buffer solution containing adenosine triphosphate;

[0015] ③ Add Phi29 DNA polymerase and deoxyribonucleoside triphosphate, and perform a rolling circle amplification reaction to obtain biological reaction solutions of different concentrations of bisphenol A;

[0016] (4) Measurement of photocurrent: Use the BiOCl / ITO electrode prepared in step (2) to measure the photocurrent values of the biological reaction solutions of different concentrations of bisphenol A prepared in step (3);

[0017] (5) Construction of a linear model: Construct a linear model according to the corresponding relationship between the photocurrent values measured in step (4) and different concentrations of bisphenol A.

[0018] In one embodiment of the present invention, in step (1), Bi(NO3)3·5H2O is dissolved in a KCl solution, and the pH is adjusted to 1-4 with hydrochloric acid; the conditions for the hydrothermal reaction are: the temperature is 180-230 °C, and the time is 22-24 h.

[0019] In one embodiment of the present invention, in step (3), the sequence of the bisphenol A aptamer is: SEQ ID NO: 1 = 5'-CCG GTG GGT GGT CAG GTG GGA TAG CGT TCC GCG TAT GGC CCA GCG CAT CAC GGG TTC GCA CCA-3'.

[0020] In one embodiment of the present invention, in step (3), the sequence of the padlock probe is: SEQ ID NO: 2 = 5'-P-CGG AAC GCT ATC CCA CCT GAC CAC CCA CCG GCA CTC CGC GCG AAG TGG TGC GAA CCC GTG ATG CGC TGG GCC ATA CG-3'.

[0021] In one embodiment of the present invention, in step (3), the concentration of Phi29 DNA polymerase is 0.8-1.5 U / μL; the concentration of deoxyribonucleoside triphosphate is 8.0-15.0 mmol / L.

[0022] In one embodiment of the present invention, in step (3), the rolling circle amplification reaction time is 60-90 min.

[0023] In one embodiment of the present invention, in step (4), the measurement of the photocurrent includes the following steps: adding a potassium ferrocyanide solution to the biological reaction solution of different concentrations of bisphenol A obtained in step (3), and then immersing the BiOCl / ITO electrode obtained in step (2) into the above reaction solution and reacting; finally, taking out the reacted BiOCl / ITO electrode, washing it with a buffer solution, and measuring the photocurrent on a photoelectrochemical test system to obtain the photocurrent values of different known concentrations of bisphenol A.

[0024] In one embodiment of the present invention, in step (4), the BiOCl / ITO electrode serves as the working electrode, and the Pt wire and the Ag / AgCl electrode serve as the counter electrode and the reference electrode, respectively.

[0025] In one embodiment of the present invention, in step (5), the photocurrent values obtained at different known bisphenol A concentrations are I, and the photocurrent value obtained for the sample with a bisphenol A solubility of 0 is I0. The corresponding photocurrent difference I - I0 is calculated for different concentrations. Then, a linear model is constructed using the logarithms of different known bisphenol A concentrations and the corresponding photocurrent differences.

[0026] The second object of the present invention is to provide a detection kit for bisphenol A, which uses the above construction method to quantitatively detect the concentration of bisphenol A.

[0027] In one embodiment of the present invention, a method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A includes the following steps:

[0028] (1) Preparation of BiOCl nanomaterials:

[0029] Dissolve 0.07 - 0.15 g of KCl in 18 mL of deionized water, add 0.49 - 0.97 g of Bi(NO3)3·5H2O, and stir vigorously for 10 min. Then, add 1.0 mol / L HCl to adjust the pH of the above solution to 1. Transfer the obtained suspension to a reaction kettle and react at 220 °C for 22 - 24 h. Centrifuge, wash, and dry for later use.

[0030] (2) Preparation of BiOCl / ITO electrodes:

[0031] Prepare a 2.0 mg / mL suspension of the obtained BiOCl solid powder and drop - coat it on the surface of pretreated ITO conductive glass. After natural drying, a BiOCl - modified ITO electrode can be obtained.

[0032] (3) Preparation of biological reaction solutions with different concentrations of bisphenol A:

[0033] Incubate different concentrations of bisphenol A and 10 μL of 1.0 - 1.5 μmol / L bisphenol A aptamer (sequence: SEQ ID NO: 1 = 5′-CCG GTG GGT GGT CAG GTG GGA TAG CGT TCC GCG TAT GGC CCA GCG CAT CAC GGG TTC GCA CCA-3′) with 30 μL of 40.0 mmol / L Tris–HCl buffer solution at pH = 7.5 at 37 °C for 40 min; then add 10 μL of 1.0 - 1.5 μmol / L padlock probe (sequence: SEQ ID NO: 2 = 5′-P-CGG AAC GCT ATC CCA CCT GAC CAC CCA CCG GCA CTC CGC GCG AAG TGG TGC GAA CCC GTG ATG CGC TGG GCC ATA CG-3′) and 10 μL of 40.0 mmol / L Tris–HCl buffer solution containing 10.0 mmol / L MgCl2 at pH = 7.5, and incubate for another 30 min at 37 °C; subsequently add 20 μL of 10.0 U / μL T4 DNA ligase and 32 μL of 40.0 mmol / L Tris–HCl buffer solution containing 10.0 mmol / L MgCl2 and 0.5 μmol / L adenosine triphosphate (ATP) at pH = 7.5, and react at 22 °C for 50 min. Immediately react the above solution at 95 °C for 10 min to inactivate the ligase; then cool down to 65 °C, add 5 μL of 1.0 U / μL Phi29 DNA polymerase and 32 μL of 40.0 mmol / L Tris–HCl buffer solution containing 10.0 mmol / L MgCl2, 50.0 mmol / L KCl, 5.0 mmol / L (NH4)2SO4 and 3 μL of 10.0 mmol / L deoxynucleoside triphosphate (dNTP) at pH = 7.5, and perform rolling circle amplification reaction at 37 °C. After 80 min, raise the temperature to 95 °C and keep it at a constant temperature for 10 min to inactivate the Phi29 DNA polymerase. Wait for it to cool down to room temperature naturally to obtain the biological reaction solution of different concentrations of bisphenol A;

[0034] (4) Measurement of photocurrent:

[0035] Add 50 μL of 100.0 μmol / L K4[Fe(CN)6] to the biological reaction solutions with different concentrations of bisphenol A. Use the BiOCl-modified ITO electrode as the working electrode, a Pt wire and an Ag / AgCl electrode as the counter electrode and reference electrode respectively. In a 50.0 mmol / L Tris-HCl buffer solution with pH = 8.2, measure the photocurrent under the condition that the voltage is +0.2 V relative to the Ag / AgCl reference electrode to obtain the photocurrent values of bisphenol A with different known concentrations.

[0036] (5) Linear model construction:

[0037] The photocurrent values obtained from different known concentrations of bisphenol A are I, and the photocurrent value of the sample with a bisphenol A concentration of 0 is I0. Calculate the corresponding photocurrent difference I - I0 for different concentrations; then construct a linear model using the logarithms of different known bisphenol A concentrations and the corresponding photocurrent differences.

[0038] The beneficial technical effects of the present invention are as follows:

[0039] The present invention utilizes that K4[Fe(CN)6] can combine with BiOCl nanosheets to generate electro-optical active Prussian blue analogs (PBAs), constructs a cathodic photoelectrochemical detection method for in-situ generating p-n heterojunctions, and combines the rolling circle amplification technology (RCA) to achieve ultrasensitive detection of bisphenol A. In the absence of bisphenol A, the bisphenol A aptamer is in a free state, and the RCA reaction can proceed successfully, generating PPi at the same time. PPi can combine with Bi atoms on the surface of BiOCl to form a passivation layer, preventing K4[Fe(CN)6] from combining with BiOCl nanosheets to generate PBAs, and at this time, a weak PEC signal is generated. In the presence of bisphenol A, the target will bind to the aptamer, effectively preventing the RCA reaction from proceeding, and thus not generating PPi to hinder the formation of PBAs. At this time, a strong PEC signal can be obtained. Based on this, the detection of the target bisphenol A can be realized.

[0040] The linear range of the method of the present invention is 0.01 - 1500.0 ng / mL, and the detection limit is 3.4 pg / mL. Compared with other methods for detecting bisphenol A such as chromatography (linear range is 1.0 - 50.0 ng / mL, detection limit is 0.13 ng / mL) and fluorescence immunoassay [linear range is 11.32 - 904.21 ng / mL, detection limit is 5.60 ng / mL], etc., it has higher sensitivity. The present invention does not require complex steps such as labeling / modifying and immobilizing biomolecules, and the operation is simple. Description of the Drawings

[0041] Figure 1Scanning electron microscope images of (A) BiOCl and (B) BiOCl / PBAs in Example 1;

[0042] Figure 2 Infrared spectra and Raman spectra of BiOCl, PBAs, and BiOCl / PBAs in Example 1;

[0043] Figure 3 (A) Photocurrent diagrams of BiOCl / ITO electrodes in the presence of different concentrations of bisphenol A in Example 1;

[0044] The concentrations of bisphenol A from left to right are 0.01, 0.1, 1.0, 10.0, 100.0, 500.0, 1000.0, 1500.0 ng / mL;

[0045] Figure 3 (B) Linear relationship diagram between the concentration of bisphenol A and ΔI;

[0046] Figure 4 (A) Stability of the photoelectrochemical sensor;

[0047] Figure 4 (B) Influence of interfering targets on the photocurrent generated by the BiOCl / ITO electrode under the same test conditions. Detailed implementation method

[0048] The present invention will be specifically described below in conjunction with the accompanying drawings and examples.

[0049] The raw materials described in the present invention are all commercially available unless otherwise specified.

[0050] Example 1

[0051] A method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A, comprising the following steps:

[0052] (1) Preparation of BiOCl nanomaterials:

[0053] Dissolve 0.07 g of KCl in 18 mL of deionized water, add 0.49 g of Bi(NO3)3·5H2O, and stir vigorously for 10 min; then, add 1.0 mol / L HCl to adjust the pH of the above solution to 1; transfer the obtained suspension to a reaction kettle and react at 220 °C for 22 h. Centrifuge, wash, and dry for standby;

[0054] (2) Preparation of BiOCl / ITO electrodes:

[0055] The obtained BiOCl solid powder was configured into a suspension of 2.0 mg / mL and drop-coated on the surface of pretreated ITO conductive glass. After natural drying, the BiOCl / ITO electrode was prepared.

[0056] (3) Preparation of biological reaction solutions with different bisphenol A concentrations

[0057] Bis-phenol A at different concentrations (the concentrations of bis-phenol A were 0.01, 0.1, 1.0, 10.0, 100.0, 500.0, 1000.0, 1500.0 ng / mL respectively) and 10 μL of 1.0 μmol / L bis-phenol A aptamer (sequence: SEQ ID NO: 1) were incubated with 30 μL of 40.0 mmol / L Tris–HCl buffer solution with pH = 7.5 at 37 °C for 40 min; then 10 μL of 1.0 μmol / L padlock probe (sequence: SEQ ID NO: 2) and 10 μL of 40.0 mmol / L Tris–HCl buffer solution with pH = 7.5 containing 10.0 mmol / L MgCl2 were added and incubated at 37 °C for another 30 min; subsequently, 20 μL of 10.0 U / μL T4 DNA ligase and 32 μL of 40.0 mmol / L Tris–HCl buffer solution with pH = 7.5 containing 10.0 mmol / L MgCl2 and 0.5 μmol / L adenosine triphosphate (ATP) were added and reacted at 22 °C for 50 min. Immediately, the above solution was reacted at 95 °C for 10 min to inactivate the ligase; then cooled to 65 °C, 5 μL of 1.0 U / μL Phi29 DNA polymerase and 32 μL of 40.0 mmol / L Tris–HCl buffer solution with pH = 7.5 containing 10.0 mmol / L MgCl2, 50.0 mmol / L KCl, 5.0 mmol / L (NH4)2SO4 and 3 μL of 10.0 mmol / L deoxynucleoside triphosphate (dNTP) were added and a rolling circle amplification reaction was carried out at 37 °C. After 80 min, the temperature was raised to 95 °C and kept at a constant temperature for 10 min to inactivate the Phi29 DNA polymerase. After natural cooling to room temperature, biological reaction solutions with different bisphenol A concentrations were prepared.

[0058] (4) Measurement of photocurrent:

[0059] 50 μL of 100.0 μmol / L K4[Fe(CN)6] was added to the biological reaction solutions with different concentrations of bisphenol A. Using the BiOCl / ITO electrode as the working electrode, a Pt wire and an Ag / AgCl electrode as the counter electrode and reference electrode respectively, the photocurrent was measured in a 50.0 mmol / L Tris-HCl buffer solution with pH = 8.2 under the condition that the voltage was +0.2 V relative to the Ag / AgCl reference electrode, and the photocurrent values of bisphenol A with different known concentrations were obtained.

[0060] (5) Linear model construction:

[0061] The photocurrent values obtained with different known concentrations of bisphenol A were I, and the photocurrent value of the sample with a bisphenol A concentration of 0 was I0. The corresponding photocurrent difference I - I0 was calculated for different concentrations; then a linear model was constructed using the logarithm of different known bisphenol A concentrations and the corresponding photocurrent differences.

[0062] The scanning electron microscope images of BiOCl and BiOCl / PBAs are as Figure 1 shown. It can be seen from the figure that the original BiOCl presented a square nanosheet morphology with a smooth surface. After reacting with K4[Fe(CN)6], flaky substances of different sizes appeared on the surface, which may be due to the formation of photoactive PBAs by the combination of K4[Fe(CN)6] and BiOCl nanosheets;

[0063] The infrared spectra and Raman spectra of BiOCl, PBAs, and BiOCl / PBAs are as Figure 2 shown. It can be seen from the infrared spectrum ( Figure 2 A) that two characteristic peaks appeared at 608 and 2037 cm -1 -1 for the BiOCl / PBAs sample. These two characteristic peaks were attributed to the bending vibration of the Fe(II)-CN band and the stretching vibration of the C≡N band respectively, indicating the formation of PBAs on the BiOCl surface. In addition, it can be seen from the Raman spectrum that BiOCl / PBAs showed characteristic peaks at 132, 187, 2080, and 2112 cm -1 -1, which were attributed to the A1 and E g modes of the Bi-Cl bond, and the A1 and E g modes of the C≡N bond respectively. And the above characteristic peaks showed obvious red shifts compared with the characteristic peaks of pure BiOCl and PBAs, indicating that there was a strong interaction between the surface-generated PBAs and BiOCl.

[0064] The photocurrents generated under the conditions of different concentrations of bisphenol A are as Figure 3As shown in A, the concentrations of bisphenol A from left to right are 0.01, 0.1, 1.0, 10.0, 100.0, 500.0, 1000.0, 1500.0 ng / mL in turn; the linear relationship diagram between the concentration of bisphenol A and ΔI is as Figure 3 shown in B. It can be seen from the figure that ΔI = 152.18 log [bisphenol A] + 295.98, R 2 = 0.99; the linear range is 0.01 - 1500.0 ng / mL, and the detection limit is 3.4 pg / mL.

[0065] The test results of the stability and selectivity of this method are as Figure 4 shown. By repeating the light source excitation ten times, the photocurrent response did not change significantly, indicating that this method has good stability. In addition, except for the target bisphenol A, other potential interfering substances did not change the photocurrent of the BiOCl / ITO electrode, indicating that this method has good selectivity.

[0066] Example 2:

[0067] A method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A, comprising the following steps:

[0068] (1) Preparation of BiOCl nanomaterials:

[0069] Dissolve 0.15 g of KCl in 18 mL of deionized water, add 0.97 g of Bi(NO3)3·5H2O, and stir vigorously for 10 min; then, add 1.0 mol / L HCl to adjust the pH of the above solution to 1; transfer the obtained suspension to a reaction kettle and react at 220 °C for 24 h. Centrifuge, wash, dry, and set aside;

[0070] (2) Preparation of BiOCl / ITO electrode:

[0071] Prepare the obtained BiOCl solid powder into a suspension of 2.0 mg / mL, and drop it on the surface of the pretreated ITO conductive glass. After natural drying, the BiOCl / ITO electrode is prepared;

[0072] (3) Preparation of biological reaction solutions with different bisphenol A concentrations

[0073] Incubate different concentrations of bisphenol A and 10 μL of 1.5 μmol / L bisphenol A aptamer (sequence: SEQ ID NO: 1) with 30 μL of 40.0 mmol / L Tris–HCl buffer solution at pH = 7.5 at 37 °C for 40 min; then add 10 μL of 1.5 μmol / L padlock probe (sequence: SEQ ID NO: 2) and 10 μL of 40.0 mmol / L Tris–HCl buffer solution containing 10.0 mmol / L MgCl2 at pH = 7.5, and incubate for another 30 min at 37 °C; subsequently, add 20 μL of 10.0 U / μL T4 DNA ligase and 32 μL of 40.0 mmol / L Tris–HCl buffer solution containing 10.0 mmol / L MgCl2 and 0.5 μmol / L adenosine triphosphate (ATP) at pH = 7.5, and react at 22 °C for 50 min. Immediately react the above solution at 95 °C for 10 min to inactivate the ligase; then cool down to 65 °C, add 5 μL of 1.0 U / μL Phi29 DNA polymerase and 32 μL of 40.0 mmol / L Tris–HCl buffer solution containing 10.0 mmol / L MgCl2, 50.0 mmol / L KCl, 5.0 mmol / L (NH4)2SO4 and 3 μL of 10.0 mmol / L deoxynucleoside triphosphate (dNTP) at pH = 7.5, and perform rolling circle amplification reaction at 37 °C. After 80 min, raise the temperature to 95 °C and keep it at a constant temperature for 10 min to inactivate the Phi29 DNA polymerase. Wait for it to cool down to room temperature naturally to obtain the biological reaction solution of different concentrations of bisphenol A;

[0074] (4) Measurement of photocurrent:

[0075] Add 50 μL of 100.0 μmol / L K4[Fe(CN)6] to the biological reaction solution of different concentrations of bisphenol A; use the BiOCl / ITO electrode as the working electrode, the Pt wire and the Ag / AgCl electrode as the counter electrode and the reference electrode respectively, and measure the photocurrent in 50.0 mmol / L Tris-HCl buffer solution at pH = 8.2 under the condition that the voltage is +0.2 V relative to the Ag / AgCl reference electrode to obtain the photocurrent values of different known concentrations of bisphenol A.

Claims

1. A method for constructing a sensor for cathodic photoelectrochemical detection of bisphenol A, characterized in that, The construction method includes the following steps: (1) Preparation of BiOCl nanomaterials: Dissolve Bi(NO3)3·5H2O in a KCl solution, then adjust the pH and carry out a hydrothermal reaction to obtain BiOCl nanomaterials; (2) Preparation of BiOCl / ITO electrodes: Disperse the BiOCl nanomaterials obtained in step (1) in deionized water to form a suspension; then drop the obtained suspension onto the surface of the ITO electrode and dry it to obtain BiOCl / ITO electrodes; (3) Preparation of biological reaction solutions of different concentrations of bisphenol A: ① Mix different concentrations of bisphenol A, bisphenol A aptamer and Tris–HCl buffer solution and incubate; ② Add a padlock probe and T4 DNA ligase and carry out a ligation reaction in a Tris–HCl buffer solution containing adenosine triphosphate; ③ Add Phi29 DNA polymerase and deoxyribonucleoside triphosphate and carry out a rolling circle amplification reaction to obtain biological reaction solutions of different concentrations of bisphenol A; (4) Measurement of photocurrent: Add a potassium ferrocyanide solution to the biological reaction solutions of different concentrations of bisphenol A in step (3), immerse the BiOCl / ITO electrode prepared in step (2) into the above reaction solution, and measure the photocurrent values of the biological reaction solutions of different concentrations of bisphenol A; (5) Construction of a linear model: Construct a linear model according to the corresponding relationship between the photocurrent values measured in step (4) and different concentrations of bisphenol A; The sequence of the bisphenol A aptamer is: 5′-CCG GTG GGT GGT CAG GTG GGA TAG CGT TCC GCG TATGGC CCA GCG CAT CAC GGG TTC GCA CCA-3′; The sequence of the padlock probe is: 5′-P-CGG AAC GCT ATC CCA CCT GAC CAC CCACCG GCACTC CGCGCG AAG TGG TGC GAACCC GTG ATG CGC TGG GCC ATA CG-3′.

2. The construction method according to claim 1, characterized in that In step (1), Bi(NO3)3·5H2O is dissolved in a KCl solution, and the pH is adjusted to 1-4 with hydrochloric acid; the conditions of the hydrothermal reaction are: the temperature is 180-230 °C and the time is 22-24 h.

3. The construction method according to claim 1, characterized in that In step (3), the concentration of Phi29 DNA polymerase is 0.8-1.5 U / μL; the concentration of deoxyribonucleoside triphosphate is 8.0-15.0 mmol / L.

4. The construction method according to claim 1, characterized in that In step (3), the rolling circle amplification reaction time is 60-90 min.

5. The construction method according to claim 1, characterized in that In step (4), the measurement of photocurrent includes the following steps: Add a potassium ferrocyanide solution to the biological reaction solutions of different concentrations of bisphenol A obtained in step (3), then immerse the BiOCl / ITO electrode obtained in step (2) into the above reaction solution and react; finally, take out the reacted BiOCl / ITO electrode, wash it with a buffer solution, and measure the photocurrent on a photoelectrochemical test system to obtain the photocurrent values of different known concentrations of bisphenol A.

6. The construction method according to claim 1, characterized in that, In step (4), the BiOCl / ITO electrode serves as the working electrode, and the Pt wire and the Ag / AgCl electrode serve as the counter electrode and the reference electrode, respectively.

7. The construction method according to claim 1, wherein In step (5), the photocurrent values obtained at different known bisphenol A concentrations are I, and the photocurrent value obtained from the sample with a bisphenol A solubility of 0 is I0. The corresponding photocurrent difference I - I0 is calculated for different concentrations; then, a linear model is constructed using the logarithms of different known bisphenol A concentrations and the corresponding photocurrent differences.

8. A detection kit for bisphenol A, characterized in that, The detection kit uses the construction method described in claim 1 to quantitatively detect the concentration of bisphenol A.

Images