Zirconium dioxide inorganic molecularly imprinted acetaminophen electrochemical transistor sensor, preparation method and application thereof

Abstract

The present invention relates to the design, construction and application of a zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor. The electrochemical transistor sensor includes a source electrode, a drain electrode and a gate electrode; both the source electrode and the drain electrode are disposed on a gold electrode with a chromium layer at the bottom layer, and the channel between the source electrode and the drain electrode is a single-layer graphene; in order to improve the sensitivity and accuracy of the transistor sensor in detection, the present invention uses acetaminophen as the target molecule, a gold nanoparticle / graphene composite material as the imprinting carrier, and zirconium oxychloride as the inorganic functional monomer to form a zirconia-gold nanoparticle / graphene / molecularly imprinted composite material on the surface of a glassy carbon electrode, and uses it as the gate electrode of the transistor sensor. The present invention constructs a molecularly imprinted electrochemical transistor sensor with specific selectivity for acetaminophen, which has the characteristics of high sensitivity, low detection limit and high selectivity, and can achieve accurate determination of acetaminophen in a complex urine environment.

Description

Technical Field

[0001] The present invention relates to a detection method combining inorganic molecular imprinting with an electrochemical transistor sensor, specifically using the specific recognition performance of inorganic molecular imprinting to improve the accuracy and sensitivity of the electrochemical transistor sensor in complex environments. Background Art

[0002] The graphene electrochemical transistor sensor is a new type of high-sensitivity detection platform. It combines the high conductivity of traditional electrochemical sensors and the unique amplification effect of transistors, and has a strong application momentum in the sensing field. However, for different detection substances, the electrode surface of the transistor sensor must be modified with different recognition molecules. It still faces severe challenges in terms of selectivity and universality during the detection process. Molecularly imprinted polymers are polymers that have specific recognition effects on specific molecules. Due to their characteristics of structural predictability, recognition specificity, and application universality, molecular imprinting is often used as the recognition unit of chemical sensors. It should be emphasized that although molecular imprinting exhibits significant recognition characteristics in sensors, their stability during repeated elution and rebinding processes remains a major issue. Functional monomers are an important part of molecular imprinting, providing specific functional groups to form pre-polymerization complexes with target molecules. Compared with common organic polymer imprinted membranes, inorganic molecular imprinted membranes have the characteristics of corrosion resistance, high temperature resistance, and high strength. However, so far, there has been no relevant literature report on using zirconium dioxide inorganic polymers as molecular imprinted membranes.

[0003] Traditional molecular imprinted membranes usually have low conductivity, which severely limits the application of molecular imprinting in the sensor field. Although molecular imprinted membranes have specific recognition capabilities and can effectively improve the selectivity and sensitivity of sensors, there are few reports on their combination with transistor sensors. No one has proposed a study on functionalizing the gate of a transistor sensor with zirconium dioxide as an inorganic molecular imprinting layer.

[0004] In the prior arts CN107907580A and CN112229890A, the gate materials are used to prepare transistor sensors for organophosphorus pesticides with gold / zirconium dioxide composite nanoparticles and zirconium dioxide / reduced graphene oxide nanocomposites respectively. Zirconium dioxide materials are involved in the above patents, but zirconium dioxide only plays a simple bonding role for parathion-methyl in them, so the selectivity of these sensors is limited. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a zirconia inorganic molecularly imprinted electrochemical transistor sensor aiming at the lack of selectivity of the above-mentioned transistor electrochemical sensor in a complex detection environment, realizing the specific recognition and detection of paracetamol in a complex human body fluid environment such as urine, and having the characteristics of high sensitivity, low detection limit and wide detection range.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0007] The zirconia inorganic molecularly imprinted electrochemical transistor sensor includes a source electrode, a drain electrode and a gate electrode; wherein the source electrode and the drain electrode are arranged on a gold layer with a chromium layer at the bottom (see Figure 5 ), the channel between the source electrode and the drain electrode is the channel of the molecularly imprinted electrochemical transistor sensor, and the channel uses a wet-transferred single-layer graphene; the gate electrode of the molecularly imprinted transistor sensor uses paracetamol as the target molecule, a gold nanoparticle / graphene composite material as the imprinting carrier, and zirconium oxychloride as the inorganic functional monomer, and a molecularly imprinted polymer is formed on a glassy carbon electrode by cyclic voltammetry electro-polymerization method, and the target molecule is eluted to obtain a glassy carbon electrode modified with a zirconia-gold nanoparticle / graphene / molecularly imprinted composite material.

[0008] The present invention provides a preparation method of the above-mentioned zirconia inorganic molecularly imprinted electrochemical transistor sensor for paracetamol, and the main steps are as follows:

[0009] (1) Evaporate a chromium layer and a gold layer on a glass substrate, with the gold layer placed above the chromium layer, and set the source electrode and the drain electrode of the electrochemical transistor sensor; the channel between the source electrode and the drain electrode is the channel of the electrochemical transistor sensor.

[0010] (2) Transfer a single-layer graphene to the channel of the electrochemical transistor sensor obtained in step (1) by a wet-transfer method to obtain the source electrode, the drain electrode and the channel of the electrochemical transistor sensor with a single-layer graphene as the channel.

[0011] (3) Use paracetamol as the target molecule, a gold nanoparticle / graphene composite material as the imprinting carrier, and zirconium oxychloride as the inorganic functional monomer, and perform electro-polymerization on a glassy carbon electrode by electro-polymerization method to form a molecularly imprinted polymer, and then elute the target molecule to prepare a glassy carbon electrode modified with a zirconia-gold nanoparticle / graphene / molecularly imprinted composite material as the gate electrode.

[0012] (4) Combine the gate electrode obtained in step (3) with the source electrode, the drain electrode and the channel obtained in step (2) to obtain a zirconia inorganic molecularly imprinted electrochemical transistor sensor for detecting paracetamol.

[0013] For the positions and sizes of the gate, source, and drain of the zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor described in the present invention, conventional methods can be used for selection, which does not affect its detection of acetaminophen. In step (1), the substrate is mainly a glass substrate, etc., and evaporation coating method, etc. can be used for chromium plating and gold plating; among them, the adhesion between metal chromium and glass is good, and it is preferably to chromium plate on the glass substrate and then gold plate on the chromium layer. The thickness of the chromium layer is preferably controlled at 0.3 - 1 nm, and the thickness of the gold layer is preferably controlled at 30 - 100 nm.

[0014] According to the above scheme, in step (2), the specific operation of wet transfer is as follows: Spin-coat a polymethyl methacrylate (PMMA) film on the single-layer graphene of the copper substrate to protect the integrity of the single-layer graphene, and then place it on the upper layer of the copper etching solution to etch the copper substrate to obtain the single-layer graphene spin-coated with the PMMA film; Use the molecularly imprinted electrochemical sensor obtained in step (1) to pick up the single-layer graphene spin-coated with the PMMA film, and then soak it in acetone to dissolve the PMMA film on the single-layer graphene, so as to transfer the single-layer graphene to the channel of the electrochemical transistor sensor obtained in step (1).

[0015] According to the above scheme, in step (3), the glassy carbon electrode modified with the zirconia-gold nanoparticle / graphene / molecularly imprinted composite material is used as the gate of the electrochemical transistor sensor. The specific operation process of step (3) is as follows:

[0016] (1) Mix the graphene oxide solution and the Nafion solution, and drop-coat it on the surface of the glassy carbon electrode and dry it; among them, the concentration of the graphene oxide solution is 0.15 - 0.75 mg mL -1 , the volume ratio of the Nafion solution to the graphene oxide solution is (1 - 5):100; after the graphene oxide solution and the Nafion solution are mixed, the dropping amount on the glassy carbon electrode is 5 - 15 μL / 0.07 cm 2 ; the concentration of the Nafion solution is 3 - 8%;

[0017] (2) Prepare a mixed solution of HAuCl 4 , ZrOCl 2 , acetaminophen and KCl as the polymerization solution; among them, the concentration of HAuCl 4 is 0.75 - 1.25 mM, the concentration of ZrOCl 2 is 3 - 8 mM, the concentration of acetaminophen is 0.15 - 0.5 mM, and the concentration of KCl is 0.05 - 0.3 M;

[0018] (3) Immerse the glassy carbon electrode obtained in step (1) in the polymerization solution and perform electro-polymerization using cyclic voltammetry. After the electro-polymerization reaction is completed, a functionalized glassy carbon electrode is obtained. Among them, the voltage of cyclic voltammetric electro-polymerization is 0.0 V to -1.2 V, and the number of electro-polymerization cycles is 5 to 13 cycles;

[0019] (4) Elute the functionalized glassy carbon electrode obtained in step (3) with p-acetaminophen in the eluent to obtain a glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite. Among them, the eluent is prepared by mixing methanol and acetic acid in a volume ratio of (8 to 10):1.

[0020] The present invention also provides a method for detecting p-acetaminophen using the above-mentioned zirconia inorganic molecularly imprinted electrochemical transistor sensor, and the main steps are as follows:

[0021] (1) Immerse the above-mentioned electrochemical transistor sensor in a buffer solution, and then detect the channel current value I at equilibrium as the blank: 0

[0022] (2) On the basis of (1), add buffer solutions containing different concentrations of p-acetaminophen dropwise. Each time when equilibrium is reached, read the channel current value I, subtract the blank current value I 0 , and obtain the channel current change value ΔI = I - I of the above-mentioned electrochemical transistor sensor in buffer solutions with different concentrations of p-acetaminophen 0 ;

[0023] (3) Using the channel current change value ΔI of the above-mentioned electrochemical transistor sensor in buffer solutions with different concentrations of p-acetaminophen obtained in step (2) as the ordinate and the logarithm of the p-acetaminophen concentration as the abscissa, establish a calibration curve for detecting p-acetaminophen using the electrochemical transistor sensor of the present invention, and further realize the quantitative analysis and detection of p-acetaminophen in the test solution.

[0024] The main technical concept of the present invention is as follows: The present invention uses a glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite as the gate of an electrochemical transistor sensor. The -OH groups in zirconia can strongly bind to the -OH / -CONH- groups of paracetamol through hydrogen bonds, and after elution treatment, an imprinted cavity with specific recognition for the target molecule is formed. Secondly, the large specific surface area and high electrical conductivity brought by gold nanoparticles and graphene can effectively improve the conductivity of the molecularly imprinted electrochemical sensor. During the detection process, the electrochemical transistor sensor is immersed in a phosphate buffer solution (PBS) (pH = 7.4) containing a certain concentration of paracetamol. The target molecule paracetamol is specifically recognized and adsorbed by the imprinted cavity on the surface of the gate. Under the gate voltage and the high electrical conductivity brought by gold nanoparticles and graphene, the paracetamol adsorbed on the electrode surface undergoes an electrochemical reaction, generating electron transfer, resulting in a change in the voltage of the gate relative to the channel, causing a change in the carrier concentration of graphene in the channel, and thus a change in the channel current. The present invention detects the concentration of the analyte paracetamol by the change in the channel current, and shows extremely high sensitivity in the detection of paracetamol, with a detection limit of 0.1 nM, realizing the specific binding and detection of paracetamol in complex human body fluid environments such as urine.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] First of all, by introducing the molecular imprinting technology, using zirconium oxychloride as the inorganic functional monomer and paracetamol as the target molecule, zirconium oxychloride and paracetamol are copolymerized, so that the obtained zirconia has imprinted holes complementary to the target molecule in terms of spatial shape, size and chemical functional groups, greatly improving the selectivity and sensitivity of the sensor for specific detection of the target molecule. The detection limit reaches 0.1 nM, realizing the specific binding and detection of paracetamol in complex human body fluid environments such as urine, and having the characteristics of high selectivity, low detection limit, and wide detection range. At the same time, it has the advantages of simple operation, good portability, fast response, stable and accurate. Description of the Drawings

[0027] Figure 1 Scanning electron micrograph of zirconia-gold nanoparticle / graphene / non-molecularly imprinted composite (ZrO 2 -NIP-Au / rGO) in Comparative Example 1 of the present invention.

[0028] Figure 2 Scanning electron micrograph of zirconia-gold nanoparticle / graphene / molecularly imprinted composite (ZrO 2 -MIP-Au / rGO) before elution in Example 1 of the present invention.

[0029] Figure 3 Scanning electron microscope image after elution of the zirconia-gold nanoparticle / graphene / molecularly imprinted composite material (ZrO 2 -MIP-Au / rGO) in Example 1 of the present invention.

[0030] Figure 4 Selectivity effect diagrams of ZrO 2 -MIP-Au / rGO and ZrO 2 -NIP-Au / rGO in the performance test of the present invention.

[0031] Figure 5 Schematic structural diagram of the zirconia inorganic molecularly imprinted electrochemical transistor sensor in Application Example 2 of the present invention.

[0032] Figure 6 In Application Example 2 of the present invention, changes in the transfer curves of the zirconia inorganic molecularly imprinted electrochemical transistor sensor in PBS buffer solutions with different concentrations of acetaminophen.

[0033] Figure 7 In Application Example 2 of the present invention, time-current curves of the zirconia inorganic molecularly imprinted electrochemical transistor sensor for different concentrations of acetaminophen in PBS buffer solution.

[0034] Figure 8 In Application Example 2 of the present invention, working curve of the zirconia inorganic molecularly imprinted electrochemical transistor sensor for detecting acetaminophen. Detailed implementation manners

[0035] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the present invention is not limited to the following embodiments only.

[0036] In the following embodiments, the glassy carbon electrode is polished before use. The specific method is as follows: The glassy carbon electrode (GCE) with a diameter of 3 mm is polished successively on alumina powders with particle sizes of 0.3 μm and 0.5 μm; then, the polished glassy carbon electrode is successively placed in deionized water, ethanol, and deionized water for ultrasonic washing for 3 min, taken out and dried with high-purity nitrogen; then, the glassy carbon electrode is placed in a solution containing 5 mmol / L of K 3 [Fe(CN) 6 and 0.1 mol / L of KCl solution, and cyclic voltammetry detection is carried out in the potential range of -0.2 V to +0.6 V until stable oxidation-reduction peaks of K 3 [Fe(CN) 6 appear, and it can be considered that the glassy carbon electrode is polished smoothly and the polishing is completed, denoted as S0.

[0037] In the following embodiments, the diameter of the glassy carbon electrode is 3 mm, and the specific distribution of the source and drain is that the channel spacing is 250 μcm. Specifically, as shown in Figure 5 ; the gate is a glassy carbon electrode modified with a zirconia-gold nanoparticle / graphene / molecularly imprinted composite material.

[0038] Example 1

[0039] A glassy carbon electrode modified with a zirconia-gold nanoparticle / graphene / molecularly imprinted composite material, and its preparation method specifically includes the following steps:

[0040] 1) Add 5 mg of monolayer graphite oxide to 10 mL of deionized water and ultrasonically disperse for 1 h to obtain a 0.5 mg / mL -1 graphene solution; take 1 mL of the graphene solution, add 30 μL of 5% Nafion solution thereto, and shake evenly. Measure 10 μL of the above mixture and drop-coat it on the surface of a 0.07 cm 2 glassy carbon electrode, and let it dry naturally.

[0041] 2) Immerse the glassy carbon electrode obtained in step 1) in a polymerization solution containing 5 mM zirconium oxychloride (ZrOCl 2 ), 0.25 mM p-aminophenol (AP), 1 mM HAuCl 4 and 0.1 M KCl, and perform cyclic voltammetry electropolymerization. The starting voltage is 0.0 V, the lowest voltage is -1.2 V, the sweep rate is 20 mV / s -1 , and the number of electropolymerization cycles is 7 cycles to obtain a glassy carbon electrode modified with a molecularly imprinted polymer;

[0042] 3) Wash the glassy carbon electrode obtained in step 2) successively by magnetic stirring with an eluent of methanol:acetic acid (V:V = 9:1) and deionized water to elute p-aminophenol in the molecularly imprinted polymer, and obtain a glassy carbon electrode modified with a zirconia-gold nanoparticle / graphene / molecularly imprinted composite material (ZrO 2 -MIP-Au / rGO), denoted as S1.

[0043] A preparation method of a p-aminophenol zirconia molecularly imprinted electrochemical sensor, the specific steps are as follows:

[0044] (1) Deposit chromium and gold on a 1x1 cm glass substrate in sequence by evaporation coating. The thickness of chromium is about 0.4 nm, and the thickness of gold is about 30 nm. Set the source and drain respectively, and the channel between the source and drain is the sensor channel;

[0045] (2) A layer of poly(methyl methacrylate) (PMMA) film was spin-coated on the single-layer graphene on the copper substrate by spin-coating method to protect the integrity of the single-layer graphene, and then transferred to the surface of 0.7 M iron nitrate solution to etch the copper substrate. After the copper substrate was etched, it was washed 3 times with clean water to obtain the single-layer graphene spin-coated with PMMA film; the sensor prepared in step (1) was used to pick up the single-layer graphene spin-coated with PMMA film, and then immersed in acetone at 60 °C to dissolve the PMMA film on the single-layer graphene, so as to transfer the single-layer graphene to the channel of the sensor obtained in step (1);

[0046] (3) The glassy carbon electrode S1 modified with zirconia-gold nanoparticles / graphene / molecularly imprinted composite was used as the gate, and the source, drain and channel obtained in step (2) were used as a combination together, so as to obtain a zirconia inorganic molecularly imprinted electrochemical sensor for detecting paracetamol.

[0047] Comparative Example 1

[0048] The gate used in this comparative example was the preparation method of a glassy carbon electrode modified with zirconia-gold nanoparticles / graphene / nona-molecularly imprinted composite (ZrO 2 -NIP-Au / rGO). The difference between the preparation steps of this gate and that in Example 1 was that: in the preparation process of Comparative Example 1, the target molecule paracetamol was not added, denoted as S1 * .

[0049] As Figures 1 - 3 shown, the microscopic morphology of ZrO 2 -NIP-Au / rGO in Comparative Example 1 and ZrO 2 -MIP-Au / rGO in Example 1 before and after elution was studied and analyzed. It was found that the surface of ZrO 2 -NIP-Au / rGO was smooth, the gold nanoparticles were evenly dispersed on the surface of graphene, and zirconia was wrapped on the surface of the gold particles; the surface morphology of ZrO 2 -MIP-Au / rGO in the present invention before elution was similar to that of ZrO 2 -NIP-Au / rGO, which indicated that the eluent did not damage the zirconia imprinted layer. Among them, the size of the gold nanoparticles was about 35 nm; when ZrO 2 -MIP-Au / rGO was eluted, the surface became rough, which indicated that the target molecule paracetamol was eluted, leaving an imprint cavity with recognition function on the surface, which not only increased the specific surface area of the imprinted composite, but also provided active sites for the adsorption of the target molecule.

[0050] Comparative Example 2

[0051] The gate used in this comparative example is the preparation method of a glassy carbon electrode modified with polypyrrole-gold nanoparticle / graphene / molecularly imprinted composite material, and its preparation steps are as follows:

[0052] 1) Add 5 mg of monolayer graphite oxide to 10 mL of deionized water and ultrasonically disperse for 1 h to obtain a graphene solution; take 1 mL of the graphene solution, add 30 μL of 5% Nafion solution thereto, and shake evenly. Measure 10 μL of the above mixture and drop it on the surface of a clean glassy carbon electrode, and let it dry naturally.

[0053] 2) Immerse the glassy carbon electrode obtained in step 1) in a solution containing 1 mM HAuCl 4 and 0.1 M KCl solution for electroreduction, with the starting voltage of 0.0 V, the lowest voltage of -1.2 V, the sweep rate of 20 mV s -1 , and the number of cycles of 7; then, immerse the obtained electrode again in an acetonitrile solution containing 0.05 M pyrrole, 0.25 mM p-aminophenol (AP), and 0.05 M lithium perchlorate (LiClO 4 ) for electropolymerization, with the starting voltage of 0.0 V, the highest voltage of +1.0 V, the sweep rate of 100 mV s -1 , and the number of cycles of 10, to obtain a glassy carbon electrode modified with a molecularly imprinted polymer;

[0054] 3) Use acetonitrile as the eluent and deionized water to magnetically stir and wash the glassy carbon electrode obtained in step 2) in turn to elute p-aminophenol in the molecularly imprinted polymer, and obtain a glassy carbon electrode modified with polypyrrole-gold nanoparticle / graphene / molecularly imprinted composite material, denoted as S2.

[0055] Comparative Example 3

[0056] The gate used in this comparative example is the preparation method of a glassy carbon electrode modified with poly(3,4-ethylenedioxythiophene)-gold nanoparticle / graphene / molecularly imprinted composite material, and its preparation steps are as follows:

[0057] 1) Add 5 mg of monolayer graphite oxide to 10 mL of deionized water and ultrasonically disperse for 1 h to obtain a graphene solution; take 1 mL of the graphene solution, add 30 μL of 5% Nafion solution thereto, and shake evenly. Measure 10 μL of the above mixture and drop it on the surface of a clean glassy carbon electrode, and let it dry naturally.

[0058] 2) Immerse the glassy carbon electrode obtained in step 1) in a solution containing 1 mM HAuCl 4 and 0.1 M KCl solution for electroreduction, with the starting voltage of 0.0 V, the lowest voltage of -1.2 V, the sweep rate of 20 mV s -1, number of cycles: 7 cycles; afterwards, the obtained electrode was immersed again in an acetonitrile solution containing 0.2 M 3,4-ethylenedioxythiophene, 0.25 mM acetaminophen (AP), and 0.05 M lithium perchlorate (LiClO 4 ), and electro-polymerization was carried out. The starting voltage was 0.0 V, the maximum voltage was +1.4 V, the sweep rate was 100 mV s -1 , number of cycles: 10 cycles, to obtain a glassy carbon electrode modified with a molecularly imprinted polymer;

[0059] 3) The glassy carbon electrode obtained in step 2) was successively cleaned by magnetic stirring using acetonitrile as the eluent and deionized water to elute acetaminophen in the molecularly imprinted polymer, obtaining a glassy carbon electrode modified with poly(3,4-ethylenedioxythiophene)-gold nanoparticles / graphene / molecularly imprinted composite material, denoted as S3.

[0060] Performance test

[0061] (1) The glassy carbon electrodes S1 - S3 obtained in Example 1 and Comparative Examples 2 - 3 were respectively enriched in a 10 μM PBS and acetaminophen solution with pH = 7.4 for 12 min. After reaching equilibrium, differential pulse voltammetry was used to measure acetaminophen. The change value of the response current of acetaminophen was denoted as ΔI (μA). The measurement potential range was 0.2 - 0.6 V, the pulse amplitude was 0.05 V, the pulse width was 0.04 s, the pulse period was 0.1 s, and the rest time was 2 s. The results are shown in Table 1.

[0062] Table 1

[0063] No S0 S1 S2 S3 ΔI (μA) 0.22 42.86 10.44 14.18

[0064] As can be seen from the results in Table 1, compared with the glassy carbon electrodes modified with common conductive polymer layers (polypyrrole, poly(3,4-ethylenedioxythiophene)) and gold nanoparticles / graphene / molecularly imprinted composite materials, the glassy carbon electrode modified with zirconia-gold nanoparticles / graphene molecularly imprinted composite material has the highest detection current response to acetaminophen. This is attributed to the fact that during the adsorption process, the zirconia inorganic imprinted layer can specifically recognize and bind to acetaminophen through hydrogen bonds, increasing the adsorption amount of acetaminophen on the electrode surface. In addition, the excellent conductivity and catalytic performance of gold nanoparticles and graphene can effectively improve the conductivity of the zirconia-gold nanoparticles / graphene molecularly imprinted composite material and promote the rapid redox reaction of acetaminophen on the functionalized glassy carbon electrode. Therefore, it is confirmed that the zirconia-gold nanoparticles / graphene molecularly imprinted composite material has a good imprinting effect and can achieve specific recognition of the target molecule acetaminophen.

[0065] (2) The blank glassy carbon electrode, the glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite in Example 1, and the glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / none-molecularly imprinted composite obtained in Comparative Example 1 were respectively enriched in a 10 μM PBS and p-acetaminophen solution with pH = 7.4 for 12 min. After the adsorption reached equilibrium, differential pulse voltammetry was used to determine p-acetaminophen, and the change value of the response current of p-acetaminophen was denoted as ΔI (μA). The measurement potential range was 0.2 - 0.6 V, the pulse amplitude was 0.05 V, the pulse width was 0.04 s, the pulse period was 0.1 s, and the rest time was 2 s. The results are shown in Table 2.

[0066] Table 2

[0067] No S0 S1 S1* ΔI (μA) 0.22 42.86 20.88

[0068] The results in Table 2 show that the current response value of the glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite for detecting p-acetaminophen is more than twice that of the glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / none-molecularly imprinted composite. This indicates that the glassy carbon electrode modified with zirconia-gold nanoparticle / graphene molecularly imprinted composite has a good imprinting effect and can achieve specific recognition of the target molecule p-acetaminophen.

[0069] (3) Glucose (glu), ascorbic acid (AA), urea (Urea), dopamine (DA), L-cysteine, glycine, acetanilide (AAA), p-aminophenol (PAP), and 4-nitrophenol (4-NP) with the same concentration (10 μM) were respectively used as interfering substances to study the selectivity of the glassy carbon electrodes modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite and zirconia-gold nanoparticle / graphene / none-molecularly imprinted composite obtained in Example 1 and Comparative Example 1. The results are as Figure 4 shown.

[0070] From Figure 4 the results, it can be seen that the glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite prepared in the present invention has specific recognition performance for p-acetaminophen and good selectivity.

[0071] Application Example 2

[0072] The method for detecting p-acetaminophen using the zirconia inorganic molecularly imprinted electrochemical transistor sensor prepared in Example 1 is specifically as follows:

[0073] (1) For the above-mentioned zirconia inorganic molecularly imprinted acetaminophen transistor electrochemical sensor, set the V of the digital source meter DS = 0.06V, the scanning voltage of the gate is 0 - 1V. When the detection reaches equilibrium, add acetaminophen solutions with different concentrations in sequence to test the transfer curve; as Figure 6 shown, the addition of acetaminophen causes the Dirac point of the channel graphene to shift to the left, indicating that N-type doping occurs in the graphene at this time;

[0074] (2) Set the V of the digital source meter DS = 0.06V, V G = 0.5V, immerse the above-mentioned electrochemical transistor sensor in PBS buffer solution (0.2M, pH = 7.4). When the detection reaches equilibrium, the channel current value I 0 at this time is used as the blank;

[0075] (3) On the basis of step (2), add buffer solutions containing different concentrations of acetaminophen. When equilibrium is reached again, read the channel current value I, subtract the blank current value I 0 , and obtain the current change value ΔI = I - I 0 of the channel of the above-mentioned electrochemical transistor sensor. Figure 7 is the time-current curve of the channel of the electrochemical transistor sensor;

[0076] Add buffer solutions containing different concentrations of acetaminophen. The corresponding relationship between the acetaminophen concentration and the current at equilibrium is shown in Table 3:

[0077] Table 3

[0078]

[0079]

[0080] (4) Taking the channel current change value △I of the sensor obtained in step (3) in buffer solutions with different concentrations of acetaminophen as the ordinate and the logarithm of the acetaminophen concentration C AP as the abscissa, establish the working curve for detecting acetaminophen by the electrochemical transistor sensor of the present invention △I a (μA) = 9.043 + 2.232LogC AP , R 2 = 0.950, (0.1 - 100 nM); △I b (μA) = 36.27 + 28.69LogC AP , R 2 = 0.993 (0.1 - 4000 μM), as Figure 7 shown, △I a and △Ib is the concentration C of acetaminophen AP The corresponding change value △I of the channel current when it takes different value ranges.

[0081] (5) To investigate the practicability of this method, the above-mentioned electrochemical transistor sensor was used to detect the content of acetaminophen in a urine environment.

[0082] After centrifuging the collected human urine, it was adjusted to pH = 7.4 with PBS buffer solution. The sensor was placed in the above urine for measurement. After the detection reached equilibrium, the test solution was added dropwise, and the current I at the equilibrium of the reaction was read. 0 . Next, a standard addition recovery experiment was carried out, and the results are shown in Table 4.

[0083] Table 4

[0084]

[0085] It can be seen from the results in Table 4 that the measured relative standard deviations are all lower than 7%, indicating that this sensor can be used for the detection of acetaminophen in a complex urine environment. And, from Figure 7 it can be known that: the detection range of this sensor for acetaminophen in a complex urine environment is 0.1 nM to 4 mM, and the change value of the channel current of the sensor shows a good linear relationship with the logarithm of the added acetaminophen concentration, and the detection limit can reach 0.1 μM.

[0086] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several improvements and transformations can still be made, and these all belong to the protection scope of the present invention.

Claims

1. Zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor, including a source electrode, a drain electrode and a gate electrode. The source electrode and the drain electrode are both arranged on a gold layer with a chromium layer at the bottom. The channel between the source electrode and the drain electrode is a single-layer graphene. It is characterized in that the gate electrode uses acetaminophen as the target molecule, gold nanoparticle / graphene composite as the imprinting carrier, zirconium oxychloride as the inorganic functional monomer, and forms a molecularly imprinted polymer on a glassy carbon electrode through cyclic voltammetry electropolymerization method. After eluting the target molecule, a glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite is obtained.

2. Preparation method of zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor, It is characterized in that including the following steps: (1) Deposit a chromium layer and a gold layer on a glass substrate in sequence, and select them as the source electrode and the drain electrode respectively; (2) Adopt the wet transfer method to transfer a single-layer graphene between the source electrode and the drain electrode obtained in step (1) as the channel; (3) Use acetaminophen as the target molecule, gold nanoparticle / graphene composite as the imprinting carrier, zirconium oxychloride as the inorganic functional monomer, form a molecularly imprinted polymer on a glassy carbon electrode through electropolymerization method, and then elute the target molecule to prepare a glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite as the gate electrode; The combination of the gate electrode and the source electrode, the drain electrode and the channel is the molecularly imprinted electrochemical transistor sensor for acetaminophen.

3. The preparation method of zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 2, It is characterized in that the specific operation process of step (3) is: (1) Mix the graphene oxide solution and the Nafion solution, drop-coat it on the surface of the glassy carbon electrode and dry it; (2)Prepare a mixed solution of HAuCl 4 , ZrOCl 2 , paracetamol and KCl as the polymerization solution; (3) Immerse the glassy carbon electrode obtained in step (1) in the polymerization solution and carry out electropolymerization by cyclic voltammetry. After the electropolymerization reaction is completed, a glassy carbon electrode functionalized with a molecularly imprinted polymer is obtained; (4) Elute acetaminophen from the functionalized glassy carbon electrode obtained in step (3) in an eluent composed of methanol and acetic acid to obtain a glassy carbon electrode modified with zirconia-gold nanoparticle / graphene / molecularly imprinted composite.

4. The preparation method of zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 3, It is characterized in that The concentration of the graphene oxide solution is 0.15 - 0.75 mg / mL -1 , and the volume ratio of the Nafion solution to the graphene oxide solution is (1 - 5):100; after the graphene oxide solution and the Nafion solution are mixed evenly, the drop-coating amount on the glassy carbon electrode is 5 - 15 μL / 0.07 cm 2 .

5. The preparation method of zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 3, It is characterized in that In the polymerization solution, the concentration of HAuCl 4 is 0.75 - 1.25 mM, the concentration of ZrOCl 2 is 3 - 8 mM, the concentration of paracetamol is 0.15 - 0.5 mM, and the concentration of KCl is 0.05 - 0.3 M.

6. The preparation method of zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 2 or 3, It is characterized in that The voltage for cyclic voltammetry electropolymerization is 0.0~-1.2V, the number of electropolymerization cycles is 3~13, and the scan rate is 10~30mVs -1 .

7. The preparation method of zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 2 or 3, It is characterized in that in step (4), the eluent is composed of methanol and acetic acid mixed in a volume ratio of (8~10):

1.

8. Method for detecting acetaminophen by the zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 1, It is characterized in that Including the following steps: (1) Immerse the electrochemical transistor sensor into a buffer solution, and then detect the channel current value I at equilibrium as a blank control: 0 , as a blank control: (2) Immerse the above-mentioned electrochemical transistor sensor in buffer solutions with different concentrations of acetaminophen, detect the channel current value I at equilibrium, subtract the blank value, and obtain the current change value ΔI = I - I of the channel of the electrochemical transistor sensor. 0 ; (3) Taking the change value ΔI of the channel current of the electrochemical transistor sensor in the buffer solution of different concentrations of acetaminophen in step (2) as the ordinate and the logarithm value of the acetaminophen concentration as the abscissa, establishing a calibration curve for detecting acetaminophen by the electrochemical transistor sensor, and further realizing the quantitative analysis and detection of acetaminophen in the test solution.

9. The method for detecting acetaminophen by the zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 8, characterized in that the linear range of the calibration curve is 0.1 nM to 4 mM, and the detection limit is 0.1 nM.

10. The method for detecting acetaminophen by the zirconia inorganic molecularly imprinted acetaminophen electrochemical transistor sensor according to claim 8, characterized in that the test solution is human body fluid, including urine, sweat, and saliva.

Images